International Journal of Rock Mechanics and Mining Sciences, 2021
Abstract Waves propagating through rocks when intersected with joints gets transmitted or reflect... more Abstract Waves propagating through rocks when intersected with joints gets transmitted or reflected. Joints or discontinuities in a rock affect the amplitude and velocity of the transmitted and reflected waves propagating through it. The changes occurring on a transmitted wave is following the properties of the incident wave namely frequency, amplitude, wavelength and the rockmass properties namely joint angle, joint roughness, joint stiffness, number of joints. In the present work, the effect of different parameters on the wave properties is understood with the help of experimental and numerical studies. The experimental study is conducted with the help of ultrasonic pulse velocity (UPV) test on artificially simulated gypsum samples. The corresponding numerical studies and subsequent extensions are done using the Universal Distinct Element Code (UDEC). Both rock mass properties as well as wave characteristics play a significant role in the wave propagation characteristics. Empirical relationships are proposed for the estimation of wave velocity against different rock joint parameters.
Rock mass is found to be mostly heterogeneous, anisotropic and discontinuous in nature and its st... more Rock mass is found to be mostly heterogeneous, anisotropic and discontinuous in nature and its strength and deformation behaviour is usually highly variable. This highly variable and spatially varying rock mass properties are attempted to be modelled in the present study using the random field modelling to characterize the material. A suitable property correlation function is adopted in the analysis namely uniform and lognormal distributions. FLAC is used to implement the model and study the effect of the corresponding material property variations. Special FISH functions were written for a combined approach of Monte Carlo simulation with variation of material properties. The implemented model used to analyze slope, where there is significant variation in the material proprieties, demonstrates the efficiency and usefulness of the model.
International. Journal of Mining & Geo-Engineering, 2016
Tunnelling through cities underlain by soft soil, commonly associated with soil movement around t... more Tunnelling through cities underlain by soft soil, commonly associated with soil movement around the tunnels and subsequent surface settlement. The predication of ground movement during the tunnelling and optimum support pressure could be based on analytical, empirical or the numerical methods. The commonly used Earth pressure balance (EPB) tunneling machines, uses the excavated soil in a pressurised head chamber to apply a support pressure to the tunnel face during excavation. This face pressure is a critical responsibility in EPB tunnelling because as the varying pressure can lead to collapse of the face. The objective of the present study is to evalute the critical supporting face pressure and grout pressure by observing the vertical deformation and horizontal displacement of soil body during tunneling. The face pressure and grout pressures were varied to see how they might influence the magnitude of surface settlements/heave. A numerical model using PLAXIS-3D tunnel has been deve...
Crack growth in rocks with preexisting flaws is of real concern for many rock engineering applica... more Crack growth in rocks with preexisting flaws is of real concern for many rock engineering applications. The present paper considers the flaw that has a narrow gap that eventually gets clos...
Tunneling through cities underlain by soft soil, is commonly associated with soil movement around... more Tunneling through cities underlain by soft soil, is commonly associated with soil movement around the tunnels and subsequently surface settlement. The predication of ground movement during a tunnelling project and optimum support pressure could be based on analytical, empirical or the numerical methods. The commonly used Earth Pressure Balance (EPB) tunneling machines, make use of the excavated soil in a pressurized head chamber to exert a support pressure to the tunnel face during excavation. This face pressure is a critical paramater in EPB tunnelling because the varying pressure can lead to the total failure and collapse of the face. The objective of the present study was to evalute the critical supporting face pressure and grout pressure by observation of the vertical deformation and horizontal displacement of soil body during tunneling. The face pressure and grout pressures were varied to see how they might influence the magnitude of surface settlements/heave. A numerical model...
International Journal of Geosynthetics and Ground Engineering, 2017
Squeezing is one of the major problems during tunnel construction in weak geological formations. ... more Squeezing is one of the major problems during tunnel construction in weak geological formations. There are empirical and semi-empirical solutions available to capture squeezing behavior in rocks given by many researchers based on extensive case studies. An investigation showed that these solutions are not always consistent and many times found to underestimate the behavior of rock mass for squeezing failure. So these solutions can be considered as preliminary estimates in predicting squeezing problem and can’t be considered as the final solution in designing the structure. In the present study, numerical analysis of a case study is been carried out using FLAC after investigating with empirical methods. Numerical analysis is performed using Generalised Hoek–Brown (GHB) criterion and the displacements obtained systematically compared with the observed values from the field. The numerical model is found to be efficient in capturing the deformation characteristics and squeezing behavior...
Landslide is a major natural hazard, which possesses serious threat to human population and vario... more Landslide is a major natural hazard, which possesses serious threat to human population and various other infrastructures such as road, rail routes and other structures in the hilly terrain. Nilgiris district, located in southern state of Tamil Nadu in India, is basically a hilly region, lying at an elevation of 1000–2600 m above Mean Sea Level (MSL). The district regularly receives rainfall during both the southwest and the northeast monsoons. The average rainfall in this region is between 1500 and 3000 mm. Due to the steep slopes and heavy rainfall during monsoons, the district is highly prone to landslides. In recent times, occurrence of landslides in Nilgiris is increased due to sudden burst of development activities in the region. The present study gives an overview of landslide events and remedial options practiced so far in Nilgiris and emphasises the importance of geotechnical investigation in that region. The history of landslide events has been collected and soil samples h...
International Journal of Rock Mechanics and Mining Sciences, 2021
Abstract Waves propagating through rocks when intersected with joints gets transmitted or reflect... more Abstract Waves propagating through rocks when intersected with joints gets transmitted or reflected. Joints or discontinuities in a rock affect the amplitude and velocity of the transmitted and reflected waves propagating through it. The changes occurring on a transmitted wave is following the properties of the incident wave namely frequency, amplitude, wavelength and the rockmass properties namely joint angle, joint roughness, joint stiffness, number of joints. In the present work, the effect of different parameters on the wave properties is understood with the help of experimental and numerical studies. The experimental study is conducted with the help of ultrasonic pulse velocity (UPV) test on artificially simulated gypsum samples. The corresponding numerical studies and subsequent extensions are done using the Universal Distinct Element Code (UDEC). Both rock mass properties as well as wave characteristics play a significant role in the wave propagation characteristics. Empirical relationships are proposed for the estimation of wave velocity against different rock joint parameters.
Rock mass is found to be mostly heterogeneous, anisotropic and discontinuous in nature and its st... more Rock mass is found to be mostly heterogeneous, anisotropic and discontinuous in nature and its strength and deformation behaviour is usually highly variable. This highly variable and spatially varying rock mass properties are attempted to be modelled in the present study using the random field modelling to characterize the material. A suitable property correlation function is adopted in the analysis namely uniform and lognormal distributions. FLAC is used to implement the model and study the effect of the corresponding material property variations. Special FISH functions were written for a combined approach of Monte Carlo simulation with variation of material properties. The implemented model used to analyze slope, where there is significant variation in the material proprieties, demonstrates the efficiency and usefulness of the model.
International. Journal of Mining & Geo-Engineering, 2016
Tunnelling through cities underlain by soft soil, commonly associated with soil movement around t... more Tunnelling through cities underlain by soft soil, commonly associated with soil movement around the tunnels and subsequent surface settlement. The predication of ground movement during the tunnelling and optimum support pressure could be based on analytical, empirical or the numerical methods. The commonly used Earth pressure balance (EPB) tunneling machines, uses the excavated soil in a pressurised head chamber to apply a support pressure to the tunnel face during excavation. This face pressure is a critical responsibility in EPB tunnelling because as the varying pressure can lead to collapse of the face. The objective of the present study is to evalute the critical supporting face pressure and grout pressure by observing the vertical deformation and horizontal displacement of soil body during tunneling. The face pressure and grout pressures were varied to see how they might influence the magnitude of surface settlements/heave. A numerical model using PLAXIS-3D tunnel has been deve...
Crack growth in rocks with preexisting flaws is of real concern for many rock engineering applica... more Crack growth in rocks with preexisting flaws is of real concern for many rock engineering applications. The present paper considers the flaw that has a narrow gap that eventually gets clos...
Tunneling through cities underlain by soft soil, is commonly associated with soil movement around... more Tunneling through cities underlain by soft soil, is commonly associated with soil movement around the tunnels and subsequently surface settlement. The predication of ground movement during a tunnelling project and optimum support pressure could be based on analytical, empirical or the numerical methods. The commonly used Earth Pressure Balance (EPB) tunneling machines, make use of the excavated soil in a pressurized head chamber to exert a support pressure to the tunnel face during excavation. This face pressure is a critical paramater in EPB tunnelling because the varying pressure can lead to the total failure and collapse of the face. The objective of the present study was to evalute the critical supporting face pressure and grout pressure by observation of the vertical deformation and horizontal displacement of soil body during tunneling. The face pressure and grout pressures were varied to see how they might influence the magnitude of surface settlements/heave. A numerical model...
International Journal of Geosynthetics and Ground Engineering, 2017
Squeezing is one of the major problems during tunnel construction in weak geological formations. ... more Squeezing is one of the major problems during tunnel construction in weak geological formations. There are empirical and semi-empirical solutions available to capture squeezing behavior in rocks given by many researchers based on extensive case studies. An investigation showed that these solutions are not always consistent and many times found to underestimate the behavior of rock mass for squeezing failure. So these solutions can be considered as preliminary estimates in predicting squeezing problem and can’t be considered as the final solution in designing the structure. In the present study, numerical analysis of a case study is been carried out using FLAC after investigating with empirical methods. Numerical analysis is performed using Generalised Hoek–Brown (GHB) criterion and the displacements obtained systematically compared with the observed values from the field. The numerical model is found to be efficient in capturing the deformation characteristics and squeezing behavior...
Landslide is a major natural hazard, which possesses serious threat to human population and vario... more Landslide is a major natural hazard, which possesses serious threat to human population and various other infrastructures such as road, rail routes and other structures in the hilly terrain. Nilgiris district, located in southern state of Tamil Nadu in India, is basically a hilly region, lying at an elevation of 1000–2600 m above Mean Sea Level (MSL). The district regularly receives rainfall during both the southwest and the northeast monsoons. The average rainfall in this region is between 1500 and 3000 mm. Due to the steep slopes and heavy rainfall during monsoons, the district is highly prone to landslides. In recent times, occurrence of landslides in Nilgiris is increased due to sudden burst of development activities in the region. The present study gives an overview of landslide events and remedial options practiced so far in Nilgiris and emphasises the importance of geotechnical investigation in that region. The history of landslide events has been collected and soil samples h...
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