Elastic constants and crack propagation stress thresholds of brittle rocks are important mechanic... more Elastic constants and crack propagation stress thresholds of brittle rocks are important mechanical properties for engineering applications. However, these properties are currently determined using methods with subjective interpreting procedures, which create cognitive biases leading to a higher degree of uncertainties. In this study, triaxial compression tests were conducted on Weber Sandstone collected from the Rock Springs Uplift, Wyoming. Nine rock specimens were treated in different geochemical conditions and tested for three different confining pressures at an in-situ pore pressure and temperature. A new method is proposed to systematically determine elastic constants and crack stress thresholds using linear and cubic regression functions to describe the linear and nonlinear stress–strain elastic behaviors, respectively. The statistical approach implemented in this new method eliminates bias due to the subjective interpretation of the nonlinear stress–strain data. The proposed method improves the consistency of elastic constant determinations by considering the linear elastic boundary of rocks and unambiguously determines the crack initiation threshold using the cubic regression function. Eliminating the subjectivity in data analysis, the new systematic method is beneficial for studying the nonlinear rock behavior and facilitating engineering applications.
The Wyoming DOT and Federal Highway Administration (FHWA) provide high-quality information to ser... more The Wyoming DOT and Federal Highway Administration (FHWA) provide high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. Wyoming DOT the FHWA periodically review quality issues and adjusts its programs and processes to ensure continuous quality improvement.
A topple is a common rock slope failure – and usually the cause of a rockfall – that depends on t... more A topple is a common rock slope failure – and usually the cause of a rockfall – that depends on the slope and rock geometries. This paper presents a laboratory simulation and field generation of a single-column rock topple failure. Innovative inertial measurement unit (IMU) sensors were used to collect three-dimensional acceleration and angular velocity data during four laboratory experiments to understand and characterise general toppling behaviours. A topple is identified by the gradual change in at least two gravity accelerations, the continuous increase in at least one of the angular velocities and a significant change in the linear acceleration in the direction of toppling. A field experiment showed similar sensor data patterns to those observed from the laboratory experiments. An isolated-block stability analysis of a single-column topple provides the basis for incorporating the IMU sensors into the development of future monitoring and early warning systems.
Cheddar cheese analogues were produced from skim milk in which canola oil was emulsified using ul... more Cheddar cheese analogues were produced from skim milk in which canola oil was emulsified using ultrasound to form either single (O/W) or double emulsions (W1/O/W2). The double emulsion cheese analogues (DECH) had a distinct microstructure and retained small skim milk droplets, dispersed in the fat phase, for more than 7 months of aging at 4 o C. The single emulsion cheese analogues (SECH), prepared with the same fat content as control cheeses, produced comparable yields of cheese and whey, with similar composition, although the fat droplets were more spherical and showed greater coalescence. The DECH cheese with skim milk encapsulated in the oil droplets, was harder, melted less and showed more free fatty acid development over 7 months of aging than the control cheeses. The SECH cheeses were softer than the control and also melted less effectively but did not show greater free fatty acid development.
This paper presents a comprehensive study of the impacts of three governing factors: Alkaline con... more This paper presents a comprehensive study of the impacts of three governing factors: Alkaline concentration, curing temperature and curing period on the mechanical properties of a geopolymer that include the uniaxial compressive strength, Poisson's ratio, and Young's modulus of elasticity. As literature review indicates, most of the previous research studies were focused on the effect of single factor, while there is a lack of comprehensive studies to simultaneously investigate the combined effects of all these factors, especially in a systematic experimental setup. Acknowledging this rarely exploited area of geopolymer research, this work developed a sequential experimental setup to perform a detailed study to understand the mechanical behaviors of the geopolymer as a function of alkaline concentration, curing temperature and curing period. The test results show that the compressive strength of geopolymer is mostly governed by the curing temperature as compared to alkaline concentration and curing period. Geopolymer samples cured at 60°C and 80°C give a competitive compressive strength of about 30 MPa even when prepared with less alkaline activator and cured for a shorter period. This observation is justified by the microscopic analysis of samples at each curing temperature that explains the formation of microcracks, amount of unreacted fly ash, sodium-aluminosilicate hydrate crystals (NASH), calcium-silicate hydrate (CSH) crystals and efflorescence.
This paper describes a recently completed laboratory test programme to determine the standard pro... more This paper describes a recently completed laboratory test programme to determine the standard properties of crushed base aggregates collected from 14 road projects throughout Wyoming. Eleven of 14 base aggregates were selected for resilient modulus testing performed in accordance with the Wyoming modified AASHTO T 307 procedure. Effects of moisture content, percent fines content, stresses, and gradation on base resilient modulus were assessed. Models were developed using statistical methods to estimate the resilient modulus of base materials. The NCHRP and Hicks and Monismith constitutive models were calibrated. A design chart of resilient modulus in terms of asphalt thicknesses was established to facilitate the iterative process involved in a pavement design. Finally, a design table of base properties for MEPDG Level-3 inputs was developed to facilitate the full implementation of the MEPDG. The proposed framework for developing these methods could be adopted nationally to facilitate the full implementation of MEPDG.
The presence of compliant pores in rocks is important for understanding the stress–strain behavio... more The presence of compliant pores in rocks is important for understanding the stress–strain behaviors under different stress conditions. This paper describes findings on the effect of compliant pores on the mechanical behavior of a reservoir sandstone under hydrostatic and triaxial compression. Laboratory experiments were conducted at reservoir temperature on Weber Sandstone samples from the Rock Springs Uplift, Wyoming. Each experiment was conducted at three sequential stages: (stage 1) increase in the confining pressure while maintaining the pore pressure, (stage 2) increase in the pore pressure while maintaining the confining pressure, and (stage 3) application of the deviatoric load to failure. The nonlinear pore pressure – volumetric strain relationship governed by compliant pores under low confining pressure changes to a linear behavior governed by stiff pores under higher confining pressure. The estimated compressibilities of the matrix material in sandstone samples are close t...
IEEE Transactions on Instrumentation and Measurement, 2019
This paper presents a wireless sensor network system (WSNS) for effective, reliable, and efficien... more This paper presents a wireless sensor network system (WSNS) for effective, reliable, and efficient monitoring of landslides. The system incorporates a network of wireless inertial measurement unit (IMU) sensor devices for collecting movement data, a local base station for data gathering, a capture server for data processing and storage, and a warning system. The major contributions of this paper are: 1) two approaches for defining movement thresholds; 2) landslide classification concept based on IMU sensor data patterns and magnitudes; and 3) a conceptual framework for building an intelligent and reliable wireless monitoring and warning system. The IMU sensor data collected by three-axis accelerometer and three-axis gyroscope were utilized to define the movement thresholds and classify landslides based on specially designed laboratory experiments. The performances of the IMU sensors and the base station for data collection and communication were tested through a rock-fall experiment conducted in the field conditions. The WSN-IMU system is capable of monitoring all types of slope movements independent of the triggering factors. The unique ability of the WSN-IMU system to determine landslide types allows designers and authorized personnel to predict subsequent movement pattern and duration so as to implement appropriate risk management and control measures to alleviate the socioeconomic losses. This paper outcome serves as the foundation for future studies and technological advancements that will facilitate landslide stabilization or mitigation actions as well as to predict the intensity of damages associated with those landslides.
Landslide monitoring and warning using inertial measurement units (IMUs) has shown the potential ... more Landslide monitoring and warning using inertial measurement units (IMUs) has shown the potential for remote and real-time applications. However, the studies conducted using the IMU sensors are limited to rainfall-induced landslide detection using soil moisture sensors and accelerometers for predicting slide and measuring tilt, respectively. The tilting of the slope might not occur during a slow-moving translational slide, and it may not always be possible to accurately record the soil moisture condition. The use of raw acceleration data, which is the combination of linear and gravitational accelerations, for calculating tilt or motion is another drawback of the existing studies. Hence, there is a need for a better approach to monitor slides. This paper presents two methods to define movement thresholds and criteria to identify the translational soil slides based on our understanding of the sensor data recorded during the two laboratory experiments. BNO055 sensor devices (IMU sensors) with 3-axis accelerometers and 3-axis gyroscopes were selected for this study. The linear accelerations, gravitational accelerations, and angular velocities were utilized to understand the translational soil slides by correlating the sensor behavior to that of the slope. The interpretation of the movements during the failure at each sensor location was further verified by referring to the videos recorded by two pi-cameras. The outcomes of this study confirm the applicability of the proposed IMU sensor system and the movement thresholds for effective and reliable monitoring and warning of translational soil slides.
Elastic constants and crack propagation stress thresholds of brittle rocks are important mechanic... more Elastic constants and crack propagation stress thresholds of brittle rocks are important mechanical properties for engineering applications. However, these properties are currently determined using methods with subjective interpreting procedures, which create cognitive biases leading to a higher degree of uncertainties. In this study, triaxial compression tests were conducted on Weber Sandstone collected from the Rock Springs Uplift, Wyoming. Nine rock specimens were treated in different geochemical conditions and tested for three different confining pressures at an in-situ pore pressure and temperature. A new method is proposed to systematically determine elastic constants and crack stress thresholds using linear and cubic regression functions to describe the linear and nonlinear stress–strain elastic behaviors, respectively. The statistical approach implemented in this new method eliminates bias due to the subjective interpretation of the nonlinear stress–strain data. The proposed method improves the consistency of elastic constant determinations by considering the linear elastic boundary of rocks and unambiguously determines the crack initiation threshold using the cubic regression function. Eliminating the subjectivity in data analysis, the new systematic method is beneficial for studying the nonlinear rock behavior and facilitating engineering applications.
The Wyoming DOT and Federal Highway Administration (FHWA) provide high-quality information to ser... more The Wyoming DOT and Federal Highway Administration (FHWA) provide high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. Wyoming DOT the FHWA periodically review quality issues and adjusts its programs and processes to ensure continuous quality improvement.
A topple is a common rock slope failure – and usually the cause of a rockfall – that depends on t... more A topple is a common rock slope failure – and usually the cause of a rockfall – that depends on the slope and rock geometries. This paper presents a laboratory simulation and field generation of a single-column rock topple failure. Innovative inertial measurement unit (IMU) sensors were used to collect three-dimensional acceleration and angular velocity data during four laboratory experiments to understand and characterise general toppling behaviours. A topple is identified by the gradual change in at least two gravity accelerations, the continuous increase in at least one of the angular velocities and a significant change in the linear acceleration in the direction of toppling. A field experiment showed similar sensor data patterns to those observed from the laboratory experiments. An isolated-block stability analysis of a single-column topple provides the basis for incorporating the IMU sensors into the development of future monitoring and early warning systems.
Cheddar cheese analogues were produced from skim milk in which canola oil was emulsified using ul... more Cheddar cheese analogues were produced from skim milk in which canola oil was emulsified using ultrasound to form either single (O/W) or double emulsions (W1/O/W2). The double emulsion cheese analogues (DECH) had a distinct microstructure and retained small skim milk droplets, dispersed in the fat phase, for more than 7 months of aging at 4 o C. The single emulsion cheese analogues (SECH), prepared with the same fat content as control cheeses, produced comparable yields of cheese and whey, with similar composition, although the fat droplets were more spherical and showed greater coalescence. The DECH cheese with skim milk encapsulated in the oil droplets, was harder, melted less and showed more free fatty acid development over 7 months of aging than the control cheeses. The SECH cheeses were softer than the control and also melted less effectively but did not show greater free fatty acid development.
This paper presents a comprehensive study of the impacts of three governing factors: Alkaline con... more This paper presents a comprehensive study of the impacts of three governing factors: Alkaline concentration, curing temperature and curing period on the mechanical properties of a geopolymer that include the uniaxial compressive strength, Poisson's ratio, and Young's modulus of elasticity. As literature review indicates, most of the previous research studies were focused on the effect of single factor, while there is a lack of comprehensive studies to simultaneously investigate the combined effects of all these factors, especially in a systematic experimental setup. Acknowledging this rarely exploited area of geopolymer research, this work developed a sequential experimental setup to perform a detailed study to understand the mechanical behaviors of the geopolymer as a function of alkaline concentration, curing temperature and curing period. The test results show that the compressive strength of geopolymer is mostly governed by the curing temperature as compared to alkaline concentration and curing period. Geopolymer samples cured at 60°C and 80°C give a competitive compressive strength of about 30 MPa even when prepared with less alkaline activator and cured for a shorter period. This observation is justified by the microscopic analysis of samples at each curing temperature that explains the formation of microcracks, amount of unreacted fly ash, sodium-aluminosilicate hydrate crystals (NASH), calcium-silicate hydrate (CSH) crystals and efflorescence.
This paper describes a recently completed laboratory test programme to determine the standard pro... more This paper describes a recently completed laboratory test programme to determine the standard properties of crushed base aggregates collected from 14 road projects throughout Wyoming. Eleven of 14 base aggregates were selected for resilient modulus testing performed in accordance with the Wyoming modified AASHTO T 307 procedure. Effects of moisture content, percent fines content, stresses, and gradation on base resilient modulus were assessed. Models were developed using statistical methods to estimate the resilient modulus of base materials. The NCHRP and Hicks and Monismith constitutive models were calibrated. A design chart of resilient modulus in terms of asphalt thicknesses was established to facilitate the iterative process involved in a pavement design. Finally, a design table of base properties for MEPDG Level-3 inputs was developed to facilitate the full implementation of the MEPDG. The proposed framework for developing these methods could be adopted nationally to facilitate the full implementation of MEPDG.
The presence of compliant pores in rocks is important for understanding the stress–strain behavio... more The presence of compliant pores in rocks is important for understanding the stress–strain behaviors under different stress conditions. This paper describes findings on the effect of compliant pores on the mechanical behavior of a reservoir sandstone under hydrostatic and triaxial compression. Laboratory experiments were conducted at reservoir temperature on Weber Sandstone samples from the Rock Springs Uplift, Wyoming. Each experiment was conducted at three sequential stages: (stage 1) increase in the confining pressure while maintaining the pore pressure, (stage 2) increase in the pore pressure while maintaining the confining pressure, and (stage 3) application of the deviatoric load to failure. The nonlinear pore pressure – volumetric strain relationship governed by compliant pores under low confining pressure changes to a linear behavior governed by stiff pores under higher confining pressure. The estimated compressibilities of the matrix material in sandstone samples are close t...
IEEE Transactions on Instrumentation and Measurement, 2019
This paper presents a wireless sensor network system (WSNS) for effective, reliable, and efficien... more This paper presents a wireless sensor network system (WSNS) for effective, reliable, and efficient monitoring of landslides. The system incorporates a network of wireless inertial measurement unit (IMU) sensor devices for collecting movement data, a local base station for data gathering, a capture server for data processing and storage, and a warning system. The major contributions of this paper are: 1) two approaches for defining movement thresholds; 2) landslide classification concept based on IMU sensor data patterns and magnitudes; and 3) a conceptual framework for building an intelligent and reliable wireless monitoring and warning system. The IMU sensor data collected by three-axis accelerometer and three-axis gyroscope were utilized to define the movement thresholds and classify landslides based on specially designed laboratory experiments. The performances of the IMU sensors and the base station for data collection and communication were tested through a rock-fall experiment conducted in the field conditions. The WSN-IMU system is capable of monitoring all types of slope movements independent of the triggering factors. The unique ability of the WSN-IMU system to determine landslide types allows designers and authorized personnel to predict subsequent movement pattern and duration so as to implement appropriate risk management and control measures to alleviate the socioeconomic losses. This paper outcome serves as the foundation for future studies and technological advancements that will facilitate landslide stabilization or mitigation actions as well as to predict the intensity of damages associated with those landslides.
Landslide monitoring and warning using inertial measurement units (IMUs) has shown the potential ... more Landslide monitoring and warning using inertial measurement units (IMUs) has shown the potential for remote and real-time applications. However, the studies conducted using the IMU sensors are limited to rainfall-induced landslide detection using soil moisture sensors and accelerometers for predicting slide and measuring tilt, respectively. The tilting of the slope might not occur during a slow-moving translational slide, and it may not always be possible to accurately record the soil moisture condition. The use of raw acceleration data, which is the combination of linear and gravitational accelerations, for calculating tilt or motion is another drawback of the existing studies. Hence, there is a need for a better approach to monitor slides. This paper presents two methods to define movement thresholds and criteria to identify the translational soil slides based on our understanding of the sensor data recorded during the two laboratory experiments. BNO055 sensor devices (IMU sensors) with 3-axis accelerometers and 3-axis gyroscopes were selected for this study. The linear accelerations, gravitational accelerations, and angular velocities were utilized to understand the translational soil slides by correlating the sensor behavior to that of the slope. The interpretation of the movements during the failure at each sensor location was further verified by referring to the videos recorded by two pi-cameras. The outcomes of this study confirm the applicability of the proposed IMU sensor system and the movement thresholds for effective and reliable monitoring and warning of translational soil slides.
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Papers by Kam Ng