Evaluation of Liquefaction Potential by CPTU and SDMT

Geosciences, 2018

To investigate the geotechnical soil properties of Emilia Romagna Region, a large series of in situ tests, laboratory tests and geophysical tests have been performed, particularly at the damaged city of Scortichino-Bondeno. Deep site investigations have been undertaken for the site characterization of the soil also along the Burana-Scortichino levee. Borings, Piezocone tests (CPTU) and dynamic in situ tests have been performed. Among them, Multichannel Analysis of Surface Waves test (MASW) and Seismic Dilatometer Marchetti Tests (SDMT) have been also carried out, with the aim to evaluate the soil profile of shear wave velocity (V s). Resonant Column Tests (RCT) were also performed in laboratory on reconstituted solid cylindrical specimens. The Seismic Dilatometer Marchetti Tests were performed up to a depth of 32 m. The results show a very detailed and stable shear wave profile. The shear wave profiles obtained by SDMT have been compared with other laboratory tests. A comparison between the in situ small shear strain, laboratory shear strain and shear strain obtained by empirical correlations, was also performed. Finally, using the results of SDMT tests, soil liquefaction phenomena have been analyzed with a new procedure based on SDMT, using the soil properties obtained by field and laboratory tests.

2015

The process of saturated granular soil strength and resistance reduction due to increase of pore water pressure during the earthquake, is named liquefaction. Liquefaction of saturated sandy deposits is one of the natural causes of earthquake disasters. Nigata earthquake, in 1964, in Japan, and the earthquake of Alaska, in 1964 caused dramatic damages, but they are considered as a big help on identification of liquefaction phenomena, as an important problem of Earthquake Engineering. The aim of this study is to evaluate the liquefaction, based on the data collected by Piezocone Test (CPTU) and Standard Penetration Test (SPT). These data are used to evaluate the liquefaction for a case study, in a coastal area of Albania, located in from Lalezi Bay to Hamallaj area, near Durresi city, where several residential buildings and resorts useful during the summer season are foreseen to be built. The site investigation was carried out in August December 2014 and included 8 CPTU tests until a ...

Journal of Civil Engineering and Architecture, 2015

The liquefaction is a very significant phenomenon in clayey silty soils, silty sands and also sands. The high potential of liquefaction is generally recognized when these types of soils are laid under the hydrostatic water table. Low plasticity silts, silty sands and sands are found as recent alluvial deposits in the western coastal part of Albania, especially in the sandy beaches of Adriatic Sea near Durres City. The aim of this study is to evaluate the soil liquefaction potential in the area of Golem. Ten CPTUs (cone penetration test with pore pressure measurements) are carried out for the site investigation of soils. In this paper, results of the CPTU based liquefaction analysis are presented. The data of two CPTUs (10 in total) are analyzed and factor of safety was found by considering different levels of hazard and ground water. The results of liquefaction potential analysis show that the soils in the area of Golem have a high risk of liquefaction.

Liquefaction induced movements and leftover shear strength of the soil, which is very critical for analysis. Seismic occasions have an effect on floor conditions. This phenomenon of soil reasons instability in different type of structures. This occurs as a result of numerous instances of structural breakdown. The tensions of the load from the foundations cannot be preserved by the liquefied floor. Foundations that dip into the sand deposit cause the building to sag and eventually collapse. Regions with saturated soils are best suited for soil liquefaction. So many various approaches to assessing soil liquefaction have been developed during the previous few decades for soil liquefaction assessment. Most of them use in open ground results like dynamic penetration test (SPT & CPT), paleo-seismic analysis and Shear Wave analysis & Velocity with site stratigraphy to assess the likelihood of soil strata liquefying. This article develops a more overview element based on available literature. A suggested method detailed in this review is used to identify the important soil compressibility parameters for the CPT-SPT correlations. This method helps to increase the consistency of the CPT-SPT correlations and offers a consistent pattern for crushable and non-crushable sands. Numerous empirical correlations have been proposed in siliceous soils to connect static cone tip resistance to SPT Nvalue.

Journal of Emerging Technologies and Innovative Research, 2018

Liquefaction of soil during earthquakes results in catastrophic damages to life and property. The deformations of soil during earthquakes pose a serious risk to the stability of structures. Niigata earthquake in Japan and the Bhuj earthquake in India incurred large scale damage to the buildings and dams. It is essential to evaluate the resistance of soils to liquefaction. This paper deals with understanding the process of liquefaction and estimating the liquefaction potential of soils by various laboratory tests and empirical approaches. The undrained behaviour of soils in cyclic shearing is explained with the help of cyclic triaxial testing and cyclic direct simple shear test. The results of the cyclic direct simple shear test conducted on loose Fraser river sand in Vancouver, Canada are discussed in this paper. The empirical approach developed in 1996 NCEER and 1998 NCEER/NSF workshops to determine the liquefaction potential of soils is presented. This empirical approach is a simplified procedure based on field tests which can be used in practice to evaluate the liquefaction potential of soils.

2001

The paper deals with a microzoning criterion based on CPT data to define liquefaction risk of the city of Trapani, Sicily (Italy). Zonation for liquefaction is a timdamental issue to prevent from seismic disasters since, as lessons of past earthquakes teach, liquefaction of sandy soils has been a major cause of damage to buildings. For the evaluation of the seismic risk of the municipal area of Trapani it has been chosen a scenario earthquake which may represent a possible repetition of the 1968 event. For this earthquake a Richter magnitude M= 6.0 and a maximum ground acceleration a,-= 0.3Og have been estimated. While new tools and refinements continue to be developed on the subjects of pore pressure build-up due to earthquake shaking and of liquefaction triggering, reliable evaluation methods already exist for liquefaction microzonation purposes. This study focuses on the application of a method for the evaluation of the liquefaction potential to several sites of the city of Trapani, by means of relationships between liquefaction resistance and corrected cone penetration tests (CPT) resistance.

Proceedings of the 6th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COMPDYN 2015), 2017

The paper analyses the evaluation of the liquefaction potential based on in situ tests. The four studied methods are those recommended by the NCEER and those proposed by Boulanger and Idriss. These methods are based on the cyclic stress approach, which characterizes both earthquake loading and soil liquefaction resistance in terms of cyclic stresses. Liquefaction resistance is based on two field tests results, namely SPT and CPT. An extensive analysis is carried out to understand and compare the results obtained. The factor of safety against liquefaction is discussed in terms of many parameters particularly the depth, the percentage of fines and the number of blows N. The analyzed case study is a site in Qatar. Hundreds of CPT and SPT were performed at this site where the foundation soil is calcareous sand, this kind of soil being not commonly considered in the literature. As far as factors of safety against liquefaction are concerned, the results are very close in general, and correspond to the geological and geotechnical soil profile. Analysis shows that the CPT Boulanger and Idriss method is the most conservative. The case study wants to contribute to the understanding of the factors that influence the cyclic stress approach. The SPT resistance is most commonly used but the CPT resistance approach must be gaining more fields in future earthquake geotechnical engineering projects.

World Journal of Engineering and Technology, 2015

One of the most devastating effects of earthquakes in the seismic regions is liquefaction. Many research works have been done in this field and at present different methods are available for the liquefaction potential assessment. The liquefaction is a very significant phenomenon in clayey silty soils, silty sands and also sands. The high potential of liquefaction is generally recognized when these type of soils are laid under the hydrostatic water table. This paper make an overview of two different methods for the evaluation of liquefaction potential, and a case study is presented. Two methods presented here are the Deterministic Approach proposed by Robertson and Wride (1998), and the Probabilistic Approach proposed by Moss and co-workers. Case study of the liquefaction potential evaluation is done for the Golem area, where geotechnical data from CPTU test were collected. The results of analysis in the Golem area show that liquefaction has medium susceptibly to occur. From the analyses, it is shown that the Probabilistic Approach gives more accurate information about the risk of liquefaction than the Deterministic Approach.

AIMS Geosciences, 2019

In the greater Lisbon area, widespread alluvial sandy deposits can be found that, due to its geology, geomorphology and high seismicity satisfy the criteria to trigger soil liquefaction if subjected to a cyclic action. Within the scope of a research project on liquefaction (LIQ2PROEARTH), an extensive geological, geotechnical, and geophysical database was established, including specific site investigation campaigns in four testing locations, in the municipalities of Benavente and Vila Franca de Xira, near Lisbon. In particular, the campaigns focused on the performance of SPT, CPTu, SDMT and geophysical tests, as well as on the collection of high-quality soil samples using advanced sampling techniques. This paper addresses the geotechnical characterization of a test site and describes the advanced sampling processes for liquefaction assessment. High-quality samples were retrieved by means of three different samplers: Mazier, Dames & Moore and Gel-Push. Preliminary assessment of the sampling quality of the collected samples has been made through the comparison of normalised field and laboratory measurements of shear wave velocity, emphasising the divergences between the different samplers. A comparative analysis of the results is presented and discussed, highlighting the identification of the layers with higher liquefaction susceptibility.

The study deals with the Liquefaction Potential Estimation of soils. Various parameters of liquefaction were studied and usin g the field methods particularly, SPT based (concepts of cyclic shear stress, cyclic stress ratio). Semi-empirical procedure for evaluation of liquefaction potential during earthquakes was carried out for the river banks of Sabarmati River front Area at Ahmedabad. Laboratory testing of bore log data, Standard Penetration test was studied at Institute of Seismological Research (ISR), Gandhinagar. SPT based assessment using Seed & Idriss (1971) [19] and Idriss & Boulanger (2008) [10] methods were used on Standard Penetration test data to estimate the factor of safety against liquefaction for the present case study. The paper gives the insight to understand liquefaction Potential of Soil and determination of the same at various depths at a particular place in the study area.