Geotechnical Investigation

A new approach is developed to determine the shear wave velocity in saturated soft to firm clays using measurements of the liquid limit, plastic limit, and natural water content with depth. The shear wave velocity is assessed using the site-specific variation of the natural water content with the effective mean stress. Subsequently, an iterative process is envisaged to obtain the clay stiffness and strength parameters. The at-rest earth pressure coefficient, as well as bearing capacity factor and rigidity index related to the cone penetration test, is also acquired from the analyses. Comparisons are presented between the measured clay parameters and the results of corresponding analyses in five different case studies. It is demonstrated that the presented approach can provide acceptable estimates of saturated clay stiffness and strength parameters. One of the main privileges of the presented methodology is the site-specific procedure developed based on the relationships between clay strength and stiffness parameters, rather than direct correlations. Despite of iterative processes, the presented approach can be easily implemented using a simple spreadsheet, benefiting both geotechnical researchers and practitioners.

The flood plain of the Nile River has been a safe dwelling throughout history. Recently with a growing population and vast growing urbanization some buildings have started to experience structural damages, which are not related to their construction design, but rather to the ground conditions around the buildings' foundations. Variations in properties of the soil supporting the buildings' foundations such as soil bearing capacity, moisture content and scouring may eventually lead to the failure of these buildings. This study is attempting to characterize the variations in the soil properties around the City Star shopping mall, in eastern Cairo, where a large building has tilted over the past few years. This tilting may lead to the collapse of the whole building if it continues at the same rate. An integrated geophysical investigation including multi-channel analysis of surface wave (MASW), ground penetrating radar (GPR) and 2-D electrical resistivity tomography (ERT) was used around the affected building to help detect possible causes of deterioration. The GPR data showed a soil-fill layer overlaying a thick bottom layer of higher moisture content. The MASW data revealed a middle layer of relatively low shear wave velocity sandwiched between two relatively high shear wave velocity layers. The ERT data showed an upper low resistivity layer overlying a high resistivity layer. Integrating the interpretations of the three geophysical methods provide a combined model that reflects lateral and vertical variation in the soil properties. This variation becomes dramatic near the tilted corner of the building.

In this paper numerical analysis is carried out to identify borehole log at a particular location of a site thus producing a number of parameters which are empirically related to SPT values. The Standard Penetration Test (SPT) remains the most common site investigation tool used throughout the world. Physical properties of soil is found by correlations with values of recommended standard N60, determined in SPT tests. Janjira Ap-proach road of ongoing Padma Multipurpose Bridge Project was considered for this study to collect 15 bore-hole log along 20 km stretch. Disturbed soil sample were collected up to 19.5m depth in every 1.5m interval to perform Sieve-analysis test. Spreadsheet was used to input of over 600 data including SPT-N values, Percent Sand & Percent Fines at depths, Reduce Level & Ground Water Table at different Chainage locations. By us-ing all these data- a mathematical model was developed in MATLAB, a high-level language and interactive environment for numerical compu...

O’Kelly, B. C. (2022) Discussion of “Advancement in estimation of undrained shear strength through fall cone tests” by Abhishek Ghosh Dastider, Santiram Chatterjee, and Prasenjit Basu. Journal of Geotechnical and Geoenvironmental Engineering 148(6): 07022005, https://doi.org/10.1061/(ASCE)GT.1943-5606.0002807

This paper presents an empirical model for estimating rock mass hydraulic conductivity of fractured Hawkesbury Sandstone in the Sydney basin. The hydraulic conductivity of a fractured crystalline rock mass can be a critical factor in tunnelling projects and dewatering designs. The Lugeon test (commonly known as the "packer test") is a common test used to estimate the in-situ permeability of a rock mass. The Packer test is carried out over a specific length (typically 3-6 m) within a borehole to reduce the range of variation of the affecting parameters. To construct a detailed profile of hydraulic conductivity through the rock mass a relatively large number of Packer tests are often required which can be costly and time consuming. The new rock mass classification system called the "HC system" was proposed by Hsu et al. (2011). The HC-system assists with the hydraulic modelling of a rock mass and is based on 4 parameters which can be readily assessed from borehole logs and borehole Televiewer data, namely Rock Quality Designation (RQD), Depth Index (DI), Gouge Content Designation (GCD) and Lithology Permeability Index (LPI). A modified new rock mass classification system called the "HC-system" or HC model has been specifically developed for Hawkesbury Sandstone in the Sydney basin. Regression analysis was conducted to assess the correlation between the calculated HC value (using the HC model) and the corresponding hydraulic conductivity from the in-situ packer tests. To confirm the feasibility of the proposed empirical HC model, the model was subsequently used to estimate the hydraulic conductivity of similar Hawkesbury Sandstone boreholes from a range of projects that also have corresponding Packer test data for comparison. This empirical HC model may assist with two important hydrogeological applications. The first application is to estimate hydraulic conductivity of fractured sandstone of similar geological set up based on HC-values. By using this approach, hydraulic conductivity data in a given site can be estimated from borehole data, which increases the reliability and confidence of the packer testing. Secondly, for in-situ aquifer tests the HC-system is a valuable new rock mass classification system for estimating the degree of permeability of a borehole. The results obtained confirm the validity and flexibility of the empirical approach to handle cases of onshore and offshore data sets, in relation to data acquisition and data reduction (optimisation).

Keywords:
Lugeon, hydraulic conductivity, Rock Quality Designation (RQD), Depth Index (DI), Gouge Content Designation (GCD), Lithology Permeability Index (LPI), Regression analysis.

For Citation:
Jembere D & Yihdego Y (2019) An empirical model to correlate rock mass classification and hydraulic conductivity, geotechnical engineering data acquisition and reduction perspective. In H. Khabbaz, A. Parsa, AHMK. Zaman & C. Rujikiatkamjorn., 2019 (eds.). INNOVATIONS IN GEOTECHNICAL CONSTRUCTION & DESIGN. Australian Geomechanics Society (AGS). PROCEEDINGS OF THE 2019 AGS SYMPOSIUM. Sydney, Australia. November 15 2019. Pages: 66-77.

URL:
https://australiangeomechanics.org/meetings/2019-sydney-symposium/

INNOVATIONS IN GEOTECHNICAL CONSTRUCTION & DESIGN. The Australian Geomechanics Society sponsored by Engineers, Australia & The Australasian Institute of Mining & Metallurgy (AusIMM)

This paper studies the behavior of a foundation on a soil reinforced by a group of end-bearing stone columns in terms of settlement reduction in oedometer condition. The group of stone columns has been reduced to equivalent concentric crowns using a finite-difference FLAC3D modeling. The obtained numerical results were compared to existing analytical and numerical methods for the prediction of the settlement of reinforced soil. It was found that the prediction of the settlement by the 3D numerical modeling of equivalent concentric crowns is less than that obtained by the actual 3D model of group of stone columns. These results have been validated through comparison between numerical, analytical, and in situ measurements collected from full-scale loading tests of stone column from recent case history.

In Greece Sanitary landfilling is the most common way of disposing of municipal solid wastes. However, one of the major problems in waste management now a days concerns is the selection procedure of the most appropriate site for their final disposal. In this paper a two-stage, multicriteria evaluation is presented. In the fist stage, in order to establish the promising sites, waste disposal is merely based on geotechnical criteria as it touches upon issues of the geoenvironment and the landscape as well as the suitability of geoenvironment for siting is depending mainly on its stability and on the danger of groundwater pollution. In the second stage these sites are evaluated using economic efficiency, environmental and technical economic criteria. It is interesting that the method sets the factors clearly and helps experts and local communities to participate. The method was easily applicable to a new landfill site selection in Northern Evoia and the results were accepted by the local communities.

Unpaved roads are designed with a small input and are constructed from the nearest available materials as possible. It requires routine and periodic maintenance, and their condition can be significantly affected by a period of excessive traffic volumes or inclement weather condition. The accurate estimation of maintenance cost is difficult. Many problems occur in the economic analysis of unpaved roads in comparison with paved roads. Defects which may affect unpaved roads are dusty, potholes, stoneness, corrugations, and rutting. Hence, it needs to apply sufficient stabilization method to strengthen and increase the durability of the unpaved road. Mechanical stabilization is an important application in engineering for different types of construction to improve the performance of road construction materials. The objective of this research was to determine the Engineering properties of natural gravel materials by mechanical stabilization method to be used in subbase material for the un...

The choice and dimensioning of the foundations are made according to the physical properties of the soil and the type of structure to be built. This research concerns the assessment of the KAMATANDA platform soil capacity, which has to support series of crushers and mechanical launders. Laboratory tests determined the physical properties (moist unit weight, dry unit weight, moisture content and particle size analysis) from soil samples taken at four different depths. In situ, we determined the mechanical properties of the soil by the dynamic cone penetrometer test. The soil of the KAMATANDA platform was the poorly graded sands by size classification. By doing the test, the moisture content, the moist unit weight and dry unit weight were increasing from 0 to 5 meters. The compactness was increasing when going deep but the rate of increase was getting less from 2.5 meters' depth. The soil presented the heterogeneities and the depth presenting much resistance to the penetration of the dynamic cone penetrometer was 2.4 meters. To avoid differential settlements, the embedding height was 1.2 meter. As per the minimum values, the dynamic resistance evaluated through the Dutch formula was 2.1MPa; however, the allowable bearing capacity, based on the dynamic resistance as per L'HERMINIER formula was 0.105MPa. We therefore noticed that, the resistance of KAMATANDA ground after dynamic cone penetrometer test relates to the compactness of the soil that grows according the depths.

Engineering failures are hard to define. They may form catastrophic disasters that are serious threats to public safety; yet, at other instances, they may be a shortcoming in the behavior or function of structures. A functional shortcoming, unforeseen and unplanned for, of an engineered element, may sometimes be considered a failure while at other times seen as tolerable or even advantageous. Engineers always regard failures as their greatest enemy; ironically, failures may be considered as their foremost teacher as well. Without failures, much of the current advances in design would not have been gained. Studying well-documented failures is important as the findings can be used to improve the designs and performance of structures. In this article, the different aspects related to failures and their prevention are explored. A conceptual model for the cost of failures is also presented. Additionally, some of the well-documented case histories of failures encompassing a wide range of geotechnical practices are highlighted and the learnt lessons are emphasized. It is demonstrated that failures may be substantially reduced by carrying out proper geotechnical site investigations, adopting flexible designs that incorporate observations during construction, applying strict site supervision, implementing geotechnical instrumentation programs and embracing risk management principles.

Using high-quality hydraulic conductivity test results for compacted soil samples with widely different gradation characteristics, 14 commonly employed empirical correlations for estimating the permeability coefficient (k) were evaluated. Comparisons of measured and predicted k values indicated most predictions were within a margin of ±100%, although they could vary by up to 500% or more. Statistical analysis indicated that high coefficients of determination obtained for these datasets can be grossly misleading, since the data may have markedly high values of the standard error of the estimate. Grain size characteristics and void ratio were identified as the most sensitive input parameters for the models investigated. On this basis and using the results of hydraulic conductivity testing performed on 20 soil samples with very different gradations, a new prediction model that expressly considers both gradation and void ratio is proposed. Test results from an additional 16 sandy soil samples were used to validate the new model, which was found to produce a fairly good distribution of data points within 95% prediction intervals and an equitable spread about the unity line in a plot of predicted against measured k values. The experimental data were also analysed using the grading entropy framework.

The consolidation test is one of the most common laboratory tests in geotechnical investigations. It is mainly utilized to assess the clay operative constrained modulus, which is an essential parameter in the settlement calculations of foundations and embankments. Recently, the non-linear numerical modelling has become more common than ever in geotechnical engineering. The state-of-art advanced geotechnical analyses focus on consideration of the nonlinear variation of soil moduli with the stress and strain levels. One of the fundamental quantities in advanced non-linear geotechnical analyses is the small strain shear modulus. It is obtained by measuring the shear wave velocity using special tests or amendments to traditional tests. Such tests and/or amendments are generally much less common and more expensive than consolidation tests. In this paper, the shear wave velocity and small strain shear modulus of soft to firm clays are evaluated from results of consolidation tests. The site-specific constants that relate the void ratio to the shear wave velocities and small strain shear moduli are concluded from the water content measurements. The proposed approach is validated by analysing two well-reported clays (viz., Ariake and Singapore clays). The results of the analyses show the viability of the proposed approach as the estimated moduli are close to the values inferred from the field shear wave velocity measurements.

Hydraulic in situ measurement of rock mass permeability by packer (Lugeon) testing is an inherent and integral element of many engineering, hydrogeological and mining investigation. This paper describes and discusses geotechnical testing in the design process from a consulting practitioner’s perspective. This study focuses on the Packer testing planning, procedure, results & interpretation. Packer test system is an optimum method for obtaining values of hydraulic conductivity in wells that are difficult to analyse using conventional slug test systems. Packer tests are carried out to assess the variability of a borehole as it intersects various hydrogeological units. It gives vertical distribution of hydraulic properties and water quality in the aquifer and usually cheaper than a nest of wells and gives more continuous record and this knowledge can often be essential for a proper design. The role, objectives, types and interpretation of testing, limitations and recommended good practices as part of the geotechnical design process are outlined through the examination of test data from a case record.

It is clear that geotechnical data gathering is one of the basic and important issues of subway tunnels and stations design. Proper and sufficient data collection from underground circumstance makes the designers stronger in order that they can decrease the design and construction risks. As there are several constraints in geotechnical investigations in urban areas especially for drilling and sampling or in-situ tests, organizing a geotechnical investigation plan will play an important role. Also, economical limitations of the projects should be considered in the mentioned planning but with no defects in technical issues. On the other hand, proper definition of investigation stages will influence the quality of the investigation and results accuracy. Since, subway projects are the combination of linear and concentrated projects from geotechnical studies point of view, therefore, an optimal planning is required to prevent extra costs. Geotechnical investigation planning, especially for subway projects, has plentiful and important points, based on mentioned issues. In this paper, the author tries to present some guidelines for geotechnical investigation planning, especially for subway projects. Required geotechnical parameters, number, depth and location of boreholes, type of in-situ and laboratory tests, which have been optimized in several subway projects in Iran and other geotechnical hazards are studied in this paper.

The emphasis in geotechnical engineering has always been on achieving appropriate solutions to specific problems and projects using a number of steps such as site investigation, soil and rock testing, modeling, empirical methods, mathematical analysis, field measurements, observation (monitoring) and design. Depending on the type and importance of the project and the availability of resources, some or all of these elements may be considered essential. In the past , there was a tendency, in some applications, to leave everything to the construction company. For example, reviewing the historical practice with regard to deep foundations, Poulos (2003) has observed that until the latter half of the 20th century, the foundation contractor controlled many aspects ranging from investigation and design to construction and remediation. However, he points out that the situation now is very different with analysis, design and construction being handled by independent specialists. This has obvious advantages, yet the disadvantages of fragmentation should not be overlooked and these might include ambiguity and conflict in technical areas as well as challenges in communication. One could safely generalize and say that these disadvantages can apply to all areas of geotechnical engineering unless there is good teamwork on projects. The more complex a geotechnical problem, the greater the care required in each of the steps and elements mentioned above and the more sophisticated the method of analysis that would be used today. Yet one must remember that much of the success achieved by geotechnical engineers in developing good methods of analysis and understanding performance was due to the significant initial progress in theoretical concepts (e. g. Terzaghi, 1943). This progress was highlighted by the discovery of the principle of effective stress for saturated soil masses leading to a better understanding of shear strength concepts and the key role of permeability of soil masses. These concepts led to a gradual appreciation of the role of excess pore water pressures generated during loading and unloading and of the differences in behavior between saturated and unsaturated soils Theories of elasticity and plasticity and the concept of limit equilibrium proved to be very useful during the early decades of development of geotechnical engineering. Thus there was a sound

Soil classification systems represent powerful tools not only to facilitate soil identification, but also to predict its possible behavior. While the use of arbitrary standards based on particle size distribution may be applicable to coarse-grained soils, those approaches based exclusively on textural principles are ineffective in classifying fine-grained soils, where clay content and its mineralogy dictate the general properties. In this sense, the measurement of plasticity represents a more appropriate parameter than particle size. This fact has led various authors and technical committees to develop fine-grained soil classification systems based on plasticity. However, the disparity of criteria makes it necessary to review them in order to glimpse the weaknesses and strengths of each of them. This paper includes the review of the six main existing proposals together with the possible variants arising from them: Casagrande (1947)-Unified Soil Classification System (USCS), American Association of State Highway and Transportation Officials (AASHTO), Federal Aviation Agency (FAA), Saito and Miki (1975), Polidori (2003, 2007, 2009) and Moreno-Maroto and Alonso-Azcarate (2017, 2018) classification charts, which are designed on the basis of Atterberg limits. After conducting a complete and thorough examination, it is shown that although the Casagrande (1947)-USCS approach is the most widely known, of all the proposals examined, only that of Moreno-Maroto and Alonso-Azcarate (2017, 2018) is based on well-founded criteria, presenting a strong predictive capacity, as well as being simple, precise and adaptable to needs.

The paper presents a case study of braced excavation using sheet pile wall in Thi Vai soft clay in South East of Ho Chi Minh city, Vietnam. The study is focused on stress-strain-displacement behavior with field monitoring of lateral displacement of the wall and settlement of the surrounding area while the 11m excavation of the pump pit was performed. Furthermore, comparison of calculated and monitored data is shown to get insight into actual behavior of the braced cut wall. It is finally found that the ratio between maximum lateral displacement to maximum excavation depth ranging from 1.12%, 3.08% and 3.35% respectively for inclinometers INC-01 to INC-03 and that between surface settlement to maximum excavation depth 0.93% without any failure of the braced excavation and effective stress analysis can be used for getting reasonable and practically accepted values of both lateral displacement and surface settlement.

Site investigation is essential prior to all construction activities of engineering structures for determining the suitability of the site for the construction of the proposed structure. The results from the site investigation gives us the information about the soil profile and the ground water table condition at the site. Various in-situ tests are carried out like Standard Penetration Test (SPT), Electrical Resistivity Technique (ERT), Vane Shear Test (VST), Plate Load Test (PLT), Pile Load Test, Flat Plate Dilatometer Test, Packer Test, Cone Penetration Test (CPT) and many others during the site exploration. The data and results obtained from these tests are essential in identifying the soil type, analyzing and the strength and deformation properties and parameters of soil as well as the ground water condition of the site. This paper intends to summarize the processes and various corrections that are involved in Standard Penetration Test (SPT) and its importance and implication in geotechnical analysis and site exploration. The tools and equipment in this test involved are cable percussion drilling rig, soil sampler (especially split spoon sampler), spirit level, boring machine and a hammer with few other miscellaneous. The soil sampler is pushed or penetrated into the ground by hammer of 63.5kg making it fall freely from a standard height of 750mm. The collected disturbed and undisturbed soil samples, hammer blows and energy are analyzed and interpreted to determine or more specifically to estimate the shear strength of soil, relative density and bearing strength of the soil at different depths. This test also helps in determining the aspects of soil which later can be improved by soil stabilizing or by any one or combination of various ground improvement techniques. In accordance of these interpretations, analysis and estimates, suitable foundation design and further construction work for the proposed structure are recommended.

Construction activities have increased many folds in the recent times due to development in economic activities. Different types of complex structures are coming up to meet the growing demand. With the significant role that the foundation design and construction play in any successful project, a geotechnical investigative report at the beginning of the process is obviously very beneficial.This paper presents the investigation to establish the sub‐surface soil stratification at the Bridge site. It also presents the evaluation of the bearing pressure and other engineering design parameters through the field and laboratory tests. This paper consists of the details about the field and laboratory test and the recommendations made based on the test results.

This paper outlines the installation of three 18m deep shafts up to 8.2m internal diameter, and two tunnels with an internal diameter of 1.2m in sand with the water table near the ground surface. The shafts were constructed using the secant piled method while the tunnels were constructed via microtunnelling. The challenges and problems associated with these difficult installations are presented, as well as the solutions used to overcome and mitigate the issues encountered. RÉSUMÉ Ce document décrit l'installation de trois puits de 18 m puits profonds allant jusqu'à 8,2 m de diamètre intérieur, et deux tunnel d'un diamètre intérieur de 1,2 m dans le sable avec une nappe phréatique près de la surface du sol. Les puits ont été construits en utilisant la méthode des pieux sécants tandis que les tunnels ont été construits par micro-tunellage. Les défis et les problèmes associés à cette installation complexe ainsi que les solutions utilisées pour surmonter et d'atténuer les problèmes rencontrés sont présentés.

The flood plain of the Nile River has been a safe dwelling throughout history. Recently with a growing population and vast growing urbanization some buildings have started to experience structural damages, which are not related to their construction design, but rather to the ground conditions around the buildings' foundations. Variations in properties of the soil supporting the buildings' foundations such as soil bearing capacity, moisture content and scouring may eventually lead to the failure of these buildings. This study is attempting to characterize the variations in the soil properties around the City Star shopping mall, in eastern Cairo, where a large building has tilted over the past few years. This tilting may lead to the collapse of the whole building if it continues at the same rate. An integrated geophysical investigation including multi-channel analysis of surface wave (MASW), ground penetrating radar (GPR) and 2-D electrical resistivity tomography (ERT) was used around the affected building to help detect possible causes of deterioration. The GPR data showed a soil-fill layer overlaying a thick bottom layer of higher moisture content. The MASW data revealed a middle layer of relatively low shear wave velocity sandwiched between two relatively high shear wave velocity layers. The ERT data showed an upper low resistivity layer overlying a high resistivity layer. Integrating the interpretations of the three geophysical methods provide a combined model that reflects lateral and vertical variation in the soil properties. This variation becomes dramatic near the tilted corner of the building.

Site investigation for different Infrastructures plays a vital role for examining the suitability of the site for different proposed construction projects. Since, it is the surveys for different factors which can be positive and/or negative influence on required activities during design and construction stages. In addition to this, site investigation is needed in order to have long life, economical and functional of different structures [5], [8]. Bridge is civil engineering structure, which has different function for given community as per social, economic, and political aspects. It is commonly built over a river, a dry valley or any depressed part of land to provide a link between the two opposite sides. Thus, before construction of such projects their site investigation is quit important. Bazo River is found in between two (Garda-Marta and Male) Woredas in Gamo zone, Ethiopia. This river has high discharge capacity of 409.7m 3 /s at dry season and 854.2m 3 /s wet season. But it was stayed without any function for the community just starting from peoples settled in the area. Hence, this research was directed to assess the site for bridge and diversion work. The main objective of this research study was Site Investigation on Bazo River for Bridge construction at Garda-Marta and Male Woredas, Ethiopia. Therefore, the study covers the feasibility of the site for bridge construction, hydrological data collection; and geotechnical investigation and analysis on subsoil materials [2], [7]. In addition to bridge foundation soil investigation, road subgrade soil investigation was also conducted to have soil class and load bearing behavior for future pavement design.

Every year, ODOT undertakes numerous pavement patching/resurfacing projects to repair pavement distress and structural failure due to soft and/or organic soils constituting the subgrade. Other than the temporary solution of patching/resurfacing, removal of weak soils and replacement with new suitable engineered fill can be used for permanent remediation. However, when problem soils are relatively deep this method can be too costly. There are various vertical column support methods used for civil engineering structures when soils are not strong enough to support the structure. Although some of these methods are utilized by several state DOTs to remediate settlement problems of existing roadways, they were not used in Ohio for this purpose. This study investigated the applicability of various vertical column support systems to improve subgrade and reduce settlements for existing roadways in Ohio. A decision matrix has been developed to identify the feasible methods. Two sites with ongoing subgrade settlements have been investigated through detailed subsurface investigations for possible implementation. Several technically feasible vertical column support methods have been identified for these sites. Lifetime cost-benefit analysis performed show that although there are some upfront costs associated with these remediation methods, the vertical column support ground improvement methods are significantly more cost effective compared to the current practice of patching/resurfacing temporary alternative during the project's lifetime, and can result in significant cost savings to ODOT and roadway users. 17.

Zemin, Zeminlerin Oluşum Mekanizmaları, Zeminlerin Mühendislik Özellikleri, Zemin Mühendisliği, Zemin Türleri, Zeminlerde Yapı ve Doku, Zeminlerin Oluşumu, Zemin Sınıflandırma Sistemleri, Zemin Mekaniği, Zemin ve Temel İlişkisi, Temel Türleri, Zemin ve Temel Arasındaki İlişki, Zemin ve Deprem İzolatörlü Temel, Zeminin Taşıma Gücü, Zemin Büyütmesi, Zemin Büyütmesi ve Deprem-Sismik Dalgalar İlişkisi, İdeal Zemin Nasıl Olmalıdır? Bozuk/Çürük/Deforme/Dirençsiz/Sağlam Olmayan Zeminler Nasıl Anlaşılır? Jeoteknik Uygulamalarda Karşılaşılan Zemin Problemleri, Zemin İyileştirme Yöntemleri Nelerdir? Zemin İyileştirme Nedir? Zemin İyileştirmesinin Amaçları Nelerdir? Zemin İyileştirme Yöntemlerinin Sınıflandırılması, Zemin İyileştirme Yönteminin Seçimi, Zemin İyileştirme Uygulamaları, Zemin Türlerine Göre Zemin İyileştirme Uygulamaları, Uygun Zemin İyileştirme Yönteminin Seçimi, Zemin İyileştirmesinin Başarısı ve Etkileri, Zemin İyileştirmesi Uygulamalarından Örnekler, Zemin İyileştirme Uygulamalarının Denetimi, Ankara, Türkay Ercan Şengöz (Türkay Ercan Şengöz tarafından yayımlanan her çeşit harita, bilgi ve belgelerin her hakkı saklıdır. Her ne şekilde ve amaçla olursa olsun bu bilgi ve belgelerin kaynak belirtilmeden kullanılması, yazılı izin alınmadan elektronik, optik, mekanik veya diğer yollarla dağıtılması, çoğaltılması, basılması, değiştirilmesi, paylaşılması, kopyalanması ve internet sitelerinde kullanılması durumunda gerekli hukuki yollara başvurulacak ve yasal işlem başlatılacaktır. Önemle duyurulur. Bu platformda veya diğer platformlarda paylaşmış olduğum tez veya akademik kapsamdaki çalışmalarımın içerisindeki bütün bilgilerin etik davranış ve akademik kurallar çerçevesinde elde edilerek sunulduğunu, akademik çalışmalarımın tez yazım kurallarına uygun olarak hazırlandığını hatırlatıyor, bana ait olan her türlü ifade ve bilginin kaynağına eksiksiz atıf yapılması gerektiğini bildiriyor, sevgi ve saygılarımı sunuyorum.)

Sari – Saat ini pembangunan skala besar sedang direncanakan di sekitar wilayah Sumedang, Jawa Barat yang meliputi pembangunan Bandara Internasional Kertajati, Jalan Tol Cisumdawu, Sentra Industri Ujungjaya, dan Bendungan Cipanas. Aktivitas pembangunan tersebut dapat terkendala permasalahan geologi teknik karena berada di atas batulempung Formasi Subang. Batulempung jenis ini diketahui memiliki pengaruh signifikan dalam aktivitas rekayasa karena sifatnya yang mudah hancur (slaking) ketika mengalami kontak dengan udara dan/ atau air. Tujuan dari penelitian ini adalah untuk mengetahui karakteristik ketahanan (durability) batulempung Formasi Subang di Daerah Ujungjaya, Kabupaten Sumedang. Penelitian dilakukan melalui observasi lapangan dan pengambilan sampel batulempung segar dalam bentuk sampel tak terganggu. Selanjutnya sampel dibawa ke laboratorium dan dilakukan pengujian slake durability serta analisis mineral lempung melalui uji difraksi sinar X. Dari hasil pengujian tersebut, batulempung Formasi Subang di daerah penelitian memiliki ketahanan rendah. Kandungan mineral monmorilonit dan pirit yang ditemukan pada sampel batulempung Formasi Subang menjadi faktor penyebab rendahnya nilai ketahanan batuan tersebut.

Abstract – Currently, a large-scale development is being planned around the Sumedang area, West Java, which includes the construction of the Kertajati international airport, Cisumdawu highway, Ujungjaya industrial centers, and Cipanas Dam. These development activities can be constrained by geological engineering problems because the constructions are conducted on the claystone of the Subang Formation.The type of this claystone is known to have a significant influence on the engineering activities because it easily slakes when in contact with air and water. The purpose of this study was to determine the durability characteristics of the Subang Formation claystone in the Ujungjaya Region, Sumedang Regency. The study was conducted with field observation and sampling of fresh undisturbed claystone. The samples were taken and tested for their slake durability characteristics as well as analysis of clay minerals by X-Ray Diffraction. Based on the results, claystone of Subang Formation in the study area have a low durability. The content of montmorillonite and pyrite that found in the sample into the factors causing the low value of the durability of claystone.

In the scope of this study, selection process of ground improvement methods for soils, which has bearing capacity, settlement, liquefaction, permeability, stability, swelling or subsidence problems, are investigated. Soil improvement methods are investigated in detail. All improvement methods can be classified as surface and deep according to depth, mechanical, hydraulical, physical, chemical, biotechnical and reinforcement according to the method of application, for clayey soils, for sandy soils and for all soils according to the soil types, and reinforcement, improvement and treatment according to application for tunnels, underwater constructions, historical buildings, and other superstructure and infrastructure projects. In this study, soil improvement methods are classified according to depth and the soil improvement methods are explained under two main headings as surface and deep soil improvement methods that improve bearing capacity, settlement, liquefaction, permeability, stability, swelling and subsidence problems. Under surface ground improvement and deep ground improvement methods, improvement by reinforcement, improvements with admixtures, surface drainage, surface compaction methods are mentioned as surface improvement methods and biotechnical, deep dynamic compaction, deep drainage, deep mixing, deep dynamic modification, electrical signal compaction, grouting, hydro-blasting compaction, thermal treatment, improvement piles, jet grouting, sand compaciton pile (SCP), microbic methods, blasting, stone column were mentoined as deep improvement methods. Moreover, most used methods, which are jet grouting, cement grouting and stone column, were examined in detail.
Commonly used ground improvement methods jet grouting, cement grouting and stone column applications’ effects on soil behaviour were investigated. Improvement effects of these three methods on same soils were estimated. Jet grouting, cement grouting and stone column methods were modelled for a site where bored piles were applied. On this site, soil profiles which have bearing capacity and potential settlement problems were determined according to the available soil investigation report. Jet grouting, cement grouting and stone column materials were designed for these profiles. All these design parameters should be checked on site. Design parameters of jet grouting, cement grouting and stone column materials were used in empirical and Plaxis software analysis which use finite element methods. All the analysis were done on Profile 1, Profile 2 and Profile 3 which are determined as having porential bearing capacity and settlement. Profile 1 includes low plasticity clay and clayey gravel, Profile 2 includes high plasticity clay, low plasticity silt and clayey sand, and Profile 3 includes silty and clayey sand. First, lengths of columns and piles were optimized for these three soil profiles. Jet grouting, cement grouting and stone column applications were investigated in 3.4 m and 13 m excavation depths, different column lenghts, and 3 D (%8.7), 2 D (%19,6) and 1,5 D (%34,9) column spacings (improvement rates) whereby empirical and numerical analysis using Plaxis program column and composite soil, Terzaghi and Meyerhof bearing capacity theories and Bowles settlement theory. According to this, each soil improvement methods has an effective column length that change with soil samples and lengths. Even though, almost all the improvement methods’ bearing capacity and settlements were affected positively with increase of improvement ratio, however, there were also rare negative effects like settlement increase of stone column in sandy soil.
In terms of bearing capacity, stone column method gave better results than jet grouting and cement grouting applications. Although, in the application of stone column, in sand, bearing capacity has increased, increase of bearing capacity for jet grouting application gave far better results. Cement grouting, which is applicable only to sand on Profile 3, increased bearing capacity significantly. However, the effect of cement grouting on the bearing capacity was less than stone column and jet grouting applications.
Furthermore, jet grouting application affect settlements far possitively for clayey, silty and even sandy soils than the other methods, moreover, the settlement problem beneficially. Stone column method, which is applied through substitution is not rigid, and cause less settlements for clayey and silty soils, but settlements were increased in sandy soils. This situation could be better when alternative compacted stone column methods are applied. Moreover, cement grouting affected settlements well, but it could not be as much as jet grouting effects.
On the other hand, there were distinct results according to analysis types. It was observed that calculated empirical bearing capacity values were higher than the one’s found the other methods. Moreover, bearing capacity that calculated according to composite soil theory is higher than calculated value by Plaxis program. Also, empirical calculation of settlements is lower than calculated value by Plaxis program. Bearing capacity of stone columns calculated by using the composite soil theory gave high bearing capacity values on the internal friction angle is high. Bowles settlement theory results gave less settlement values than the one calculated by Plaxis program. Plaxis column calculations can be considered better due to the reason that column can be evaluated separate or group.
In addition, the stone column usage in the clay and silt soils gave better results than sand. As long as cement injection can be applied, it has been observed that it contributes to the bearing capacity of loose sands and improved to settlement behaviour. Also, jet grouting method contributed significantly to settlements including clayey, silty and sandy soils, however, it did not demonstrate a good performance in bearing capacity. Jet grouting method has been shown to contribute positively to the bearing capacity on clayey and silty soils, but it has not been able to make much contributions to settlement. As a result, jet grouting method can be effective in all soil types, and it can make significant contributions to settlements in all types of soil and has a positive effect on all soil types. Stone column method has positive effects on settlements on clayey and silty soils and contributes significantly to bearing capacity in all types of soils. Although, cement grouting method has narrow application area, it contributes to the bearing capacity and settlement of loose sand.
Finally, only jet grouting application has provided sufficient bearing capacity and limit settlement values in profile 3. While the jet grouting improvement was insufficient in profile 1 and profile 2, and stone column and cement grouting were not sufficient in all profiles. The bored pile method applied can be used as an alternative to soil improvement methods under high superstructure loads. Soil improvement can be preferred for soils that are under low loads.

Engineering failures are hard to define. They may form catastrophic disasters that are serious threats to public safety; yet, at other instances, they may be a shortcoming in the behavior or function of structures. A functional shortcoming, unforeseen and unplanned for, of an engineered element, may sometimes be considered a failure while at other times seen as tolerable or even advantageous. Engineers always regard failures as their greatest enemy; ironically, failures may be considered as their foremost teacher as well. Without failures, much of the current advances in design would not have been gained. Studying well-documented failures is important as the findings can be used to improve the designs and performance of structures. In this article, the different aspects related to failures and their prevention are explored. A conceptual model for the cost of failures is also presented. Additionally, some of the well-documented case histories of failures encompassing a wide range of geotechnical practices are highlighted and the learnt lessons are emphasized. It is demonstrated that failures may be substantially reduced by carrying out proper geotechnical site investigations, adopting flexible designs that incorporate observations during construction, applying strict site supervision, implementing geotechnical instrumentation programs and embracing risk management principles.

Socialisation is a processes with the help of which a living organism is changed into a social being. It is a process through which the younger generation learns the adult role which it has to play subsequently. It is a continuous process in the life of an individual and it continues from generation to generation. Socialisation stands for the development of the human brain, body, attitude, behaviour and so forth. From the point of view of society, socialisation is the way through which society transmits its culture from generation to generation and maintains itself. From the point of view of the individual, socialisation is the process by which the individual learns social behaviour, develops his 'self.

OLIVEIRA, D. G. G. de. Optical televiewer in boreholes – methodological proposal for implementation and application in underground work. 2015. 187 f. Dissertação (Mestrado) – Instituto de Geociências, Universidade de São Paulo, São Paulo, 2015.
The rock mass characterization is an essential step in engineering geology, providing the possibility of performance prediction of this massive due to numerous requests of any work to be done. In the case of urban underground works, such as subway lines, for example, geological and geotechnical characterization of rock masses is critical for identifying geological conditions linked to its stability, being effective in determining the geotechnical parameters that influence the design of massive excavation, whether by the conventional method (NATM), or mechanized, using tunneling boring machines (TBM).
Structural features such as foliation planes, folds, faults and fracture systems deserve special attention as they are associated with weakness zones in addition to all the geomechanical characteristics of the massif. In urbanized areas, such as São Paulo Metropolitan Region (RMSP), geological, geomorphological and occupation hinders exposure and identification of these features on the surface. In this context, new techniques have been developed to facilitate access to the above features. Among these new techniques is the optical televiewer (OPTV, OTV), which aim to obtain 360° images of the borehole walls, providing what might be considered a virtual core of a borehole.
The optical televiewer has been a technology introduced in Brazil since 2001, but only recently has been published in ABGE  Borehole Manual (2013), however, there are no specifications on the acquisition methodology, interpretation and application possibilities. This paper presents suggestions for the acquisition of these images, their interpretation and suggestions of applications in engineering works, taking as an example the design in projects of underground works of the São Paulo Metro.
In the specific case of urban underground excavations ground knowledge is essential, since its construction is an activity to be developed within the urban context, which could cause significant interference with the community, resulting in a high risk to neighboring population. Added to this is the fact that a little-known mass can result in oversized contention, increasing the cost of the work or undersized, increasing its risk.
As mentioned in ISRM (1978), as the descriptions of rock masses and discontinuities become more complete and unified, it will be feasible to design engineering structures in rock reducing the costs and increasing the reliability of the interpretation and extrapolation of the results.

Keywords: Optical televiewer, geological-geotechnical investigation, rock massif characterization, urban underground excavations.

Vietnam locates in soft Hollocence ground area with great thickness, so geotechnical engineers always face challenges in dealing with soft ground treatment methods. Among those, preloading method by surcharge and/or vacuum assisted with prefabricated vertical drain (PVD) is often used to accelerate consolidation of the ground, and to reduce post-construction settlement before applying operation load throughout lifetime of the projects. Therefore, the paper is focused on using finite difference method (FDM) and constant rate of strain (CRS) consolidation test results to analyze the consolidation of a case study of soft marine clay found in South of Vietnam under surcharge preloading assisted with PVD. The approach aims at numerical solution of multi-layer model of soft clay a FDM procedure coded by the authors. Moreover, the authors determine stress-strain relation and parameters of the soft marine soil for the analysis with application of constant rate of strain consolidation tests carried out at the strain rate of 0.02%/min. The results of the analyses show good consistency between calculated and monitored data in settlement, dissipation of excess pore water pressure and un-drained strength gain of the investigated soft clay deposit. Therefore, finite difference method (FDM) with multi-layer consideration and CRS consolidation test results are applicable to the estimation of settlement of soft clays improved by PVD method in Vietnam.

In this paper, numerical analysis is carried out to identify borehole log at a particular location of
a site thus producing a number of parameters which are empirically related to SPT values. The Standard Penetration Test (SPT) remains the most common site investigation tool used throughout the world. Physical properties of soil are found by correlations with values of recommended standard N60, determined in SPT tests.
Janjira Approach road of ongoing Padma Multipurpose Bridge Project was considered for this study to collect
15 borehole log along 20 km stretch. Disturbed soil sample were collected up to 19.5m depth in every 1.5m
interval to perform Sieve-analysis test. Spreadsheet was used to input of over 600 data including SPT-N values, Percent Sand & Percent Fines at depths, Reduce Level & Ground Water Table at different Chainage locations. By using all these data- a mathematical model was developed in MATLAB, a high-level language and
interactive environment for numerical computation, visualization, and programming. Rectangular grids in
multidimensional space were created for Interpolation and/or Extrapolation for 2-D and/or 3-D gridded data
in ‘meshgrid’ format. The purposes of the study are to find vertical SPT profile & soil-profile in a particular
alignment of the site and to extract borehole log form SPT profile & soil-profile at intermittent locations of
that alignment. SPT profile is presented graphically using contour plot of matrix and soil-profile is presented
by 3-D shaded surface plots. Predicted borehole log could be useful for preliminary selection of a project site,
land use planning, zoning ordinances, pre-disaster planning, and capital investment planning. Seismic soil liquefaction was evaluated for this site in terms of the factors of safety against liquefaction (FS) along the
depths of soil profiles for different peak ground acceleration ranging 0.3g to 0.45g and earthquake magnitude
ranging 6 to 7.5 on Richter scale. Cyclic Strength Ratio (CSR) and Cyclic Resistance Ratio (CRR) was determined with 10 % probability of exceedance in 50 year using SPT-based simplified empirical procedure.
Liquefaction potential index (LPI) is evaluated at borehole locations from the obtained factors of safety (FS)
to assess the potential of liquefaction to cause damage at the surface level at the site of interest. To validate
the model, recent occurred Nepal Earthquake was taken as an example to compare the level of liquefaction
severity assessed by in-situ and predicted borehole log data.

GEOTILL Engineering (www.geotill.com) is Geotechnical Services Provider of comprehensive, and cost effective Civil and Geotechnical Engineering services for clients located throughout the Midwest in Indiana, Illinois, Michigan, Ohio, Kentucky and Missouri. Provides Geotechnical Engineering - onshore, nearshore and offshore foundations; excavations, slopes, retaining structures, tunnels, ground improvement.  Numerical Analysis in 2D and 3D for the optimized design and assessment of ground displacements and soil-structure interaction.
Tunnel Engineering – investigation, planning, design, documentation and construction supervision of tunnels for roads, rail, power supply, water supply and sewerage systems.

Sydney Metro is Australia's biggest public transport project.

Stage 2 of the project will extend metro rail from the city's northwest under Sydney Harbour, through new stations in the CBD and southwest to Bankstown.
Sydney Metro has two core components:
- Sydney Metro Northwest -now under construction and to open in the first half of 2019
- Sydney Metro City and Southwest a new twin 12.5-km tunnel linking with Sydney Metro Northwest at Chatswood
- then under Sydney Harbour, through the CBD to Sydenham and continuing 13. 4 km along the existing line to
Bankstown due for completion in 2024.
A joint venture between Parsons Brinckerhoff and AECOM (PB-AECOM JV) was appointed as the consultant for the Sydney Metro Technical Services project, which commenced in September 2014. The team will prepare a preliminary evaluation, scoping design, definition design and ultimately reference designs for the Sydney Metro Stage 2.
In November 2014 the marine geophysics contract was awarded to Earth Technology Solutions Pty Ltd and the intrusive investigation followed in April 2015 by the Golders-Douglas Partners joint venture.
As Sydney Harbour is a key element of Sydney Metro, early planning and design work included essential geotechnical investigations. Sydney Harbour is a busy waterway, so the investigation works began, after extensive consultation with all relevant harbour authorities, with standard marine geophysical surveys (reflection, 1 refraction, 1 magnetics and sonar) west of the Sydney Harbour Bridge.
Land-based investigation began in April 2015 following extensive community consultation and services searches. The firstnole (BH015) began at Blues Point with a commissioning ceremony by the NSW Premier Mike Baird. This was the start of 27 boreholes that extend from Chatswood to Sydenham. These boreholes have been planned to target and intersect the Ashfield Shale, Mittagong Formation and Hawkesbury Sandstone to assess the rocks geomechanical properties.

The shear wave velocity VS is an essential parameter in various geotechnical analyses. It can be determined using laboratory testing of undisturbed samples, in-situ geophysical measurements, or by using correlations of the shear wave velocity with the common in-situ penetration tests such as the standard penetration tests (SPT) and the cone penetration test (CPT). The latter approach is often preferred by engineers for many reasons including cost optimization of the geotechnical investigations and infeasibility of undisturbed sampling in some formations such as non-cohesive soils. Accordingly, many correlations were envisaged to determine the shear wave velocity using the CPT; these correlations were developed through statistical and regression analyses of compiled CPT and shear wave velocity databases. Yet, to date, substantial discrepancies between the existing CPT correlations and the measured shear wave velocities are still revealed when the CPT correlations are compared with more recent case histories and databases. As such, there is a continuous need to update these correlations. In this study, a proposed approach is presented to define the stress-dependency parameters of the shear wave velocity in terms of the CPT measurements. Hence, enhanced CPT correlations for the shear wave velocity and the small strain modulus in both cohesionless and cohesive soils are realised. Two case studies are analysed using the proposed CPT correlation for the shear wave velocity as well as the commonly applied correlations. It is shown that the proposed CPT-VS correlation provides consistent predictions with the measured shear wave velocity; hence, it may be considered as an enhancement to the currently adopted methods.

This paper presents some issues of geotechnical investigation for roads built on expansive soils. The aim of the study is to
provide road engineers with guidance on site investigation; field and laboratory identification of expansive soils. A clear understanding of the expansive subgrade soils behavior and their geotechnical characteristics has been of more interest to the study in order to assess properly the source of the swelling problem. Two case study sites, representative known problem-areas in Khartoum were carefully selected for geotechnical site investigation. The field exploration consisted of excavating trial pits and collecting soil samples from the subgrade. These soils were subjected to laboratory testing for measuring the particle size analysis, consistency, strength and swelling characteristics. The soils were found to have over 50% clay particles, high plasticity index more than 30% and high free swell index of
160% to 250%. The compacted samples were found to have swell potential of 7% to 15% coupled with high swelling pressure in excess of 90 kPa and low strength, CBR values less than 4%. General conclusions have been drawn from the study findings.

The study area comprises of Rosaries dam in the Blue Nile State in southeastern Sudan. The dam had been constructed above pervious layer confined between two impervious layers and this gave rise to hydrostatic pressure under the dam elements. The objectives of the study were to evaluate the present situation of relief wells in the Rosaries dam heightening project, to state and discuss optimum measures and characteristics of well design criteria of relief wells and borings and to document for profession experience in this scope of work in Sudan. The study has adopted descriptive and analytical methods which made use of previous data provided by dam implementation unit and complemented with data collected during field visit which included drill logs of wells, daily and annual reports of relief wells and borings, laboratory result of sieve test for gravel pack and aquifer materials and photographic slides. Data were processed and analyzed using Microsoft Office Excel, Rockworks15 and Auto CAD programs. The geotechnical site investigation showed that the vertical geological succession consists of pervious strata with high to moderate permeability confined between two impervious layers. This stratigraphic and lithologic setting gave rise to high hydrostatic pressure under foundations of the embankment during reservoir impounding; which threatened the stability of the dam embankments. Water level was monitored in the relief wells before and after impounding showed that all relief wells in the two embankments are working effectively and successfully. The study has recommended for monitoring and maintenance of the concrete shaft of the relief wells including secure cover and water level measurement. It also recommended for making periodic inspection, maintenance and rehabilitation for the relief wells.

A multidisciplinary geophysical and geotechnical study, including some non-invasive geophysical applications, was carried out during the restoration of the 'Villa del Casale', a Roman villa discovered near Piazza Armerina (Sicily, Italy) in 1929, famous for its Roman floor mosaics. The project aims were to characterize the geology of the subsoil and provide information for solving the main building structural problems including the subsidence of some parts of the floor and the detachment of the tesserae (i.e., the tiles) of the mosaics. Another goal was the detailed study of the underground structures of the Corridor of the Great Hunt, a part of the villa strongly affected by subsidence and detachment of mosaics.

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Abstract: In this study, the potential of pulverized waste tires (PWTs), either on their own or mixed with soil (well graded sand), to act as adsorptive fill materials was evaluated by conducting laboratory tests for accessing their adsorption and geotechnical properties. PWT (0, 5, 10, 15, 25, and 100 wt%) was mixed with soil to evaluate the removal of benzene, toluene, ethylbenzene, and xylene (BTEX) components and two heavy metal ions (Pb2+ and Cu2+). Adsorption batch tests were performed to determine the equilibrium sorption capacity of each mixture. Subsequently, compaction, direct shear, and consolidation tests were performed to establish their geotechnical properties. The results showed that BTEX had the strongest affinity based on the uptake capacity by the soil–PWT mixtures. The adsorption of BTEX increased for greater PWT content, with pure PWT having the highest adsorption capacity toward BTEX removal: uptake capacities for xylene, ethylbenzene, toluene, and benzene were 526, 377, 207 and 127 µg/g sorbent, respectively. Heavy metal removal was increased by increasing the amount of PWT up to 10 wt%, and then decreased beyond this ratio. Compacted soilePWT mixtures comprising 5–25 wt% PWT have relatively low dry unit weight, low compressibility, adequate shear capacity for many loadbearing field applications, and satisfactory adsorption of organic/inorganic contaminants, such that they could also be used as adsorptive fill materials.

Most of the topsoils encountered in United Arab Emirates and in the Arabian Peninsula are granular soils with small percentages of silt and clay. Determination of the compaction characteristics of such soils is an essential task in preparing for construction work. The accumulating experience over many years of soil testing in our laboratories suggested that there exists an underlying trend that governs the compaction characteristics of such soils. As such, a study was undertaken to assess the compaction characteristics of such soils and to develop the governing predictive equations. For the purposes of this study, 311 soil samples were collected from various locations in the United Arab Emirates, and tested for various including grain-size distribution, liquid limit, plasticity index, specific gravity of soil solids, maximum dry density of compaction, and optimum moisture content following ASTM D 1557-91 standard procedure C. Following the development of the predictive equations, a new set of 43 soil samples were collected and their compaction results were used to test the validity of predictive model. The range of variables for these soils were as follows: percent retained on US sieve #4 (R#4): 0–68; Percent passing US sieve #200 (P#200): 1–26; Liquid limit: 0–56; Plasticity index: 0–28; Specific gravity of soil solids: 2.55–2.8. Based on the compaction tests results, multiple regression analyses were conducted to develop mathematical models and nomographic solutions to predict the compaction properties of soils. The results indicated that the nomographs could predict well the maximum dry density within ±5% confidence interval and the optimum moisture content within ±3%.

Recently, Spagnoli et al. (2019) investigated the relationships between the flow index (FI) − defined as the slope of the w-log 10 N plot (where w = water content and N = number of blows) obtained from the Casagrande-cup method − and the conventional soil consistency parameters, i.e., Casagrande-cup liquid limit (LL), thread-rolling plastic limit (PL), and plasticity index (PI = LL − PL). It was concluded that the FI is poorly correlated with the PL. On the contrary, the authors reported that the LL and, more importantly, the PI both exhibited relatively strong correlations with the FI. In this regard, a linear relationship in the form of PI = 6.07 × FI (with coefficient of determination (R2) = 0.91 obtained for a database of 59 soil materials) was proposed and validated by the authors, thus allowing an indirect estimation of the PI without the need for conducting the subjective thread-rolling PL test. The work under discussion attempts to further solidify an interesting concept, as originally introduced by Sridharan, Nagaraj, and Prakash (1999), from which soil plasticity is quantified in a more objective manner. Further, it would follow that the PL can be predicted having determined the LL and FI from the experimental flow curve as PL = LL − 6.07 × FI.