— Change in geotechnical behaviour of fine grained soils under the influence of inorganic salts d... more — Change in geotechnical behaviour of fine grained soils under the influence of inorganic salts depends on the chemistry of the soil constituents and the pore fluid. The modification of soil behaviour largely depends upon the clay particles which belongs to size 0.002 mm and less and it is unique in nature. The different nature of clay is due to net electrical charge on them. In general, clay particles surface are negatively charged and its edges are positively charged. To preserve electrical neutrality the negative charge of the clay particle is balanced by the attraction of cations which are held between the layers, and on the surface of the particles. The charged clay surface together with the counter–ions in the pore water form diffuse double layer. Furthermore, the double layer is influenced by the valency of the counter–ions and the temperature. Use of salt solution as pore fluid generally causes decrease in liquid limits. The higher the cation valance, higher decrease in liqu...
SYNOPSIS: Characterisation of foundation rock is the basic requirement for taking up investigatio... more SYNOPSIS: Characterisation of foundation rock is the basic requirement for taking up investigation of a river valley project. The determination of in-situ shear strength parameters, deformation characteristics and detailed laboratory investigations of rock mass are of vital importance in order to find representative essential parameters required for designing and determining the stability of concrete gravity dam. This paper presents the details of in-situ shear and deformability tests conducted on the foundation rock of Kalpong Hydro Electric Project, North Andaman, Andaman and Nicobar Islands. The in-situ parameters obtained have been compared with results of the laboratory investigation. The results show that deformation modulus increases with increase in applied stress level. The values of shear strength parameters and deformation modulus as determined from laboratory are much higher than those evaluated from in-situ testing.
Runways are made of rigid as well as flexible pavement. Generally, flexible pavement is sandwiche... more Runways are made of rigid as well as flexible pavement. Generally, flexible pavement is sandwiched between two rigid ends. Traffic loading, age hardening, or temperature cycling typically cause fatigue and reflective cracking in flexible pavement. When cracking is present, the traditional remedy has been to apply thicker asphalt overlays. Reinforcement using an interlayer system has been demonstrated as a multipurpose solution to improve the performance, extend service life and thus to reduce maintenance cost of runway pavement. Among a large number of existing interlayer systems, glass grid along with SAMI (Stress Absorbing Membrane Interlayer) have shown effective use in pavement reinforcement with a hot mix asphalt overlay. Glass grids are composed of series of fiberglass strands coated with an elastomeric polymer and formed into a grid structure. However, SAMI is a layer of PMB (polymer-modified bitumen), which shall be laid over glass grid surface, together with a covering of a...
The permeability of soil is an essential parameter in estimating the quantity of seepage under fo... more The permeability of soil is an essential parameter in estimating the quantity of seepage under foundation of hydraulic structures, which in turn affect the stability of structures. Empirical correlations such as Hazen, Kozeny–Carman, Breyer, Slitcher, Terzaghi, USBR, Alyamani and Sen are function of grain sizes, porosity/void ratio, coefficient of uniformity (Cu), coefficient of curvature (Cc) and viscosity of pore fluids. These correlations are quite effective for preliminary assessment of permeability during prefeasibility stage. However, at the designing stage, actual measurement of permeability is very important for structural integrity. The measurement of permeability is carried out by in situ tests for assessment of foundation of hydraulic structures and also for investigation of canals in cutting. The assessment of permeability of borrow area soils for construction of embankment is determined by laboratory methods. Depending upon the size of the soil particles, gradation, interaction among the soil particles, etc. constant head and falling head laboratory tests are more popular for coarse-grained and fine-grained soil, respectively. In the present study, attempt has been made to correlate permeability values evaluated through these correlations and also through constant head laboratory test. The samples were packed in permeability mould at 95% relative density. For comparison, four different types of soils from different sources have been selected. The values of laboratory permeability and theoretical permeability obtained through correlations are compared and have been discussed in the present paper. The results are also compared with Odong Odong (J Am Sci 3(3), 2007, [1]) and same indicate close resemblance in terms of applicability of correlation for assessment of permeability of different types of sands.
International Journal for Scientific Research and Development, 2020
To measure the tensile strength, the load applied can be either tensile or compressive. The appli... more To measure the tensile strength, the load applied can be either tensile or compressive. The application of compressive load in order to induce tensile stresses can be either through point load (diametral loading) or line load. In this paper, for twelve variants of basalt and twelve variants of gneiss, an attempt has been made to correlate the two loads, i.e., point load and line load, to induce tensile failure. For each of the variants, the correlation between the point load and the line load data is discussed on the basis of recommended parameters only; in other words, the inherent variability of a given variant is not in focus here. The reported work also draws from previous researches and codes of practice. In case of Basalts, the ratios are ranging from 0.65 to 0.78. While, due to anisotropy in Gneisses, the ratio is ranging from 0.79 to 2.28, but, it is also observed that the ratio is decreasing to 0.80 as the value of anisotropy index is approaching unity. However, it can easi...
The study involves challenges faced in construction of runway pavements in the Northeastern part ... more The study involves challenges faced in construction of runway pavements in the Northeastern part of India. These runways are very much important from strategic point of view. Most of these runways constructed during the Second World War were either renovated or extended many times. These runways though renovated and extended many times still require upgrading for easy and quick access to remote areas and to facilitate the movement of modern different types of aircraft as per PCN (Pavement Classification No.) and ICAO norms. Construction/renovation of these runways to keep them active for flying in all seasons is a major challenge especially during prolong heavy rainy seasons, floods, scarcity/non-availability of construction materials, skilled man power, etc. Apart from these problems, the other challenges faced are generation of actual profile of runway as per ICAO norm, laying of DBM as grade correction layer, laying of PQC layers without development of surface cracks, cutting of ...
Dynamic displacement—time response of ballast-subgrade system is very useful result for assessing... more Dynamic displacement—time response of ballast-subgrade system is very useful result for assessing the soil behavior under dynamic loading for railway track foundation as it can help to gauge the soil suitability for the subgrade which can withstand the dynamic load without much deflection. This paper pertains to study of response of the ballast and subgrade under the dynamic load moving train using analytical and computational methods. The selected ballast and subgrade consist coarser granular material and fine-grained cohessionless material with a dense matrix, respectively. The response of the foundation of the railway track (ballast and subgrade) is presented in terms of “displacement—time” plot. These response curves have been plotted for 1 min duration. Out of this 1 min duration, dynamic load of frequency 26 Hz was applied for the first 6 s only. The analytical and computational (METLAB) results are compared with the results obtained using the FE package PLAXIS. The maximum di...
Kalej Khola H.E Project, and Suntaley H.E Projects are located in West Sikkim and east Sikkim res... more Kalej Khola H.E Project, and Suntaley H.E Projects are located in West Sikkim and east Sikkim respectively. The Kalej Khola H.E Project is located on the river Kalej Khola, a tributary of river Rangit and Suntaley H.E Project on the river Suntaley, a tributary of river Teesta. Both projects envisage construction of approximately 50 m height composite Earth and Rockfill dams with spillway on the right bank and left bank of the river respectively. Installed capacities of proposed surface power house of the two projects are 90 MW 60 MW respectively. In the present study, effect of organic content on index properties and compaction parameters of borrow area soil samples of these two has been investigated. The test results indicate that the organic content significantly alter the geotechnical properties of these samples because determination of moisture content in the samples done through oven drying methods since some of the organic content also get burn up during the oven drying the mo...
The interconnection of vesicles in basaltic flows greatly affects the engineering properties such... more The interconnection of vesicles in basaltic flows greatly affects the engineering properties such as uniaxial compressive strength, modulus of elasticity, Poisson’s ratio, tensile strength and sonic velocities. Sometimes these vesicles are filled with secondary minerals such as quartz/olivine/calcite form as amygdules (which are impermeable). In the present study, to understand effect of porosity, vesicular and amygdular basaltic flows collected from central and west-central India were investigated for these engineering properties and correlated with apparent porosity of core samples. It is observed that a good level of correlation is obtained for uniaxial compressive strength (UCS), elastic modulus (E) and Poisson’s ratio in vesicular basalts when porosity >8-10%. In case of Brazilian strengths a linearly downward trend is observed with the increase in porosity values. And, no significant correlation is observed for waves’ velocities in both variants of basalts. Keywords—apparen...
Geotechnical investigation of geomaterials is one of the most important tools to arrive at safe a... more Geotechnical investigation of geomaterials is one of the most important tools to arrive at safe and economical design of structures. Inadequate investigations many times result in non-optimal geotechnical solutions. Encounterence of geological surprises and adverse geological occurrences result in cost overrun and sometimes even compromising safety of the structures. The Himalayan Mountains in Northeast India are quite young and have a large potential for hydroelectric projects. Since this area lies in seismic Zone IV, earth and rockfill dams are more suitable in this region due to flexibility of the materials and capacity to absorb vibrations. In the present study, 135 m high earth and rockfill dam at Tlawng H. E. Project, Aizwal, Mizoram, has been considered across river Tlawng. Three potential borrow area locations were identified near the dam site to meet the requirement of impervious material for clay core of the dam. Representative soil samples were collected from the respecti...
— Change in geotechnical behaviour of fine grained soils under the influence of inorganic salts d... more — Change in geotechnical behaviour of fine grained soils under the influence of inorganic salts depends on the chemistry of the soil constituents and the pore fluid. The modification of soil behaviour largely depends upon the clay particles which belongs to size 0.002 mm and less and it is unique in nature. The different nature of clay is due to net electrical charge on them. In general, clay particles surface are negatively charged and its edges are positively charged. To preserve electrical neutrality the negative charge of the clay particle is balanced by the attraction of cations which are held between the layers, and on the surface of the particles. The charged clay surface together with the counter–ions in the pore water form diffuse double layer. Furthermore, the double layer is influenced by the valency of the counter–ions and the temperature. Use of salt solution as pore fluid generally causes decrease in liquid limits. The higher the cation valance, higher decrease in liqu...
SYNOPSIS: Characterisation of foundation rock is the basic requirement for taking up investigatio... more SYNOPSIS: Characterisation of foundation rock is the basic requirement for taking up investigation of a river valley project. The determination of in-situ shear strength parameters, deformation characteristics and detailed laboratory investigations of rock mass are of vital importance in order to find representative essential parameters required for designing and determining the stability of concrete gravity dam. This paper presents the details of in-situ shear and deformability tests conducted on the foundation rock of Kalpong Hydro Electric Project, North Andaman, Andaman and Nicobar Islands. The in-situ parameters obtained have been compared with results of the laboratory investigation. The results show that deformation modulus increases with increase in applied stress level. The values of shear strength parameters and deformation modulus as determined from laboratory are much higher than those evaluated from in-situ testing.
Runways are made of rigid as well as flexible pavement. Generally, flexible pavement is sandwiche... more Runways are made of rigid as well as flexible pavement. Generally, flexible pavement is sandwiched between two rigid ends. Traffic loading, age hardening, or temperature cycling typically cause fatigue and reflective cracking in flexible pavement. When cracking is present, the traditional remedy has been to apply thicker asphalt overlays. Reinforcement using an interlayer system has been demonstrated as a multipurpose solution to improve the performance, extend service life and thus to reduce maintenance cost of runway pavement. Among a large number of existing interlayer systems, glass grid along with SAMI (Stress Absorbing Membrane Interlayer) have shown effective use in pavement reinforcement with a hot mix asphalt overlay. Glass grids are composed of series of fiberglass strands coated with an elastomeric polymer and formed into a grid structure. However, SAMI is a layer of PMB (polymer-modified bitumen), which shall be laid over glass grid surface, together with a covering of a...
The permeability of soil is an essential parameter in estimating the quantity of seepage under fo... more The permeability of soil is an essential parameter in estimating the quantity of seepage under foundation of hydraulic structures, which in turn affect the stability of structures. Empirical correlations such as Hazen, Kozeny–Carman, Breyer, Slitcher, Terzaghi, USBR, Alyamani and Sen are function of grain sizes, porosity/void ratio, coefficient of uniformity (Cu), coefficient of curvature (Cc) and viscosity of pore fluids. These correlations are quite effective for preliminary assessment of permeability during prefeasibility stage. However, at the designing stage, actual measurement of permeability is very important for structural integrity. The measurement of permeability is carried out by in situ tests for assessment of foundation of hydraulic structures and also for investigation of canals in cutting. The assessment of permeability of borrow area soils for construction of embankment is determined by laboratory methods. Depending upon the size of the soil particles, gradation, interaction among the soil particles, etc. constant head and falling head laboratory tests are more popular for coarse-grained and fine-grained soil, respectively. In the present study, attempt has been made to correlate permeability values evaluated through these correlations and also through constant head laboratory test. The samples were packed in permeability mould at 95% relative density. For comparison, four different types of soils from different sources have been selected. The values of laboratory permeability and theoretical permeability obtained through correlations are compared and have been discussed in the present paper. The results are also compared with Odong Odong (J Am Sci 3(3), 2007, [1]) and same indicate close resemblance in terms of applicability of correlation for assessment of permeability of different types of sands.
International Journal for Scientific Research and Development, 2020
To measure the tensile strength, the load applied can be either tensile or compressive. The appli... more To measure the tensile strength, the load applied can be either tensile or compressive. The application of compressive load in order to induce tensile stresses can be either through point load (diametral loading) or line load. In this paper, for twelve variants of basalt and twelve variants of gneiss, an attempt has been made to correlate the two loads, i.e., point load and line load, to induce tensile failure. For each of the variants, the correlation between the point load and the line load data is discussed on the basis of recommended parameters only; in other words, the inherent variability of a given variant is not in focus here. The reported work also draws from previous researches and codes of practice. In case of Basalts, the ratios are ranging from 0.65 to 0.78. While, due to anisotropy in Gneisses, the ratio is ranging from 0.79 to 2.28, but, it is also observed that the ratio is decreasing to 0.80 as the value of anisotropy index is approaching unity. However, it can easi...
The study involves challenges faced in construction of runway pavements in the Northeastern part ... more The study involves challenges faced in construction of runway pavements in the Northeastern part of India. These runways are very much important from strategic point of view. Most of these runways constructed during the Second World War were either renovated or extended many times. These runways though renovated and extended many times still require upgrading for easy and quick access to remote areas and to facilitate the movement of modern different types of aircraft as per PCN (Pavement Classification No.) and ICAO norms. Construction/renovation of these runways to keep them active for flying in all seasons is a major challenge especially during prolong heavy rainy seasons, floods, scarcity/non-availability of construction materials, skilled man power, etc. Apart from these problems, the other challenges faced are generation of actual profile of runway as per ICAO norm, laying of DBM as grade correction layer, laying of PQC layers without development of surface cracks, cutting of ...
Dynamic displacement—time response of ballast-subgrade system is very useful result for assessing... more Dynamic displacement—time response of ballast-subgrade system is very useful result for assessing the soil behavior under dynamic loading for railway track foundation as it can help to gauge the soil suitability for the subgrade which can withstand the dynamic load without much deflection. This paper pertains to study of response of the ballast and subgrade under the dynamic load moving train using analytical and computational methods. The selected ballast and subgrade consist coarser granular material and fine-grained cohessionless material with a dense matrix, respectively. The response of the foundation of the railway track (ballast and subgrade) is presented in terms of “displacement—time” plot. These response curves have been plotted for 1 min duration. Out of this 1 min duration, dynamic load of frequency 26 Hz was applied for the first 6 s only. The analytical and computational (METLAB) results are compared with the results obtained using the FE package PLAXIS. The maximum di...
Kalej Khola H.E Project, and Suntaley H.E Projects are located in West Sikkim and east Sikkim res... more Kalej Khola H.E Project, and Suntaley H.E Projects are located in West Sikkim and east Sikkim respectively. The Kalej Khola H.E Project is located on the river Kalej Khola, a tributary of river Rangit and Suntaley H.E Project on the river Suntaley, a tributary of river Teesta. Both projects envisage construction of approximately 50 m height composite Earth and Rockfill dams with spillway on the right bank and left bank of the river respectively. Installed capacities of proposed surface power house of the two projects are 90 MW 60 MW respectively. In the present study, effect of organic content on index properties and compaction parameters of borrow area soil samples of these two has been investigated. The test results indicate that the organic content significantly alter the geotechnical properties of these samples because determination of moisture content in the samples done through oven drying methods since some of the organic content also get burn up during the oven drying the mo...
The interconnection of vesicles in basaltic flows greatly affects the engineering properties such... more The interconnection of vesicles in basaltic flows greatly affects the engineering properties such as uniaxial compressive strength, modulus of elasticity, Poisson’s ratio, tensile strength and sonic velocities. Sometimes these vesicles are filled with secondary minerals such as quartz/olivine/calcite form as amygdules (which are impermeable). In the present study, to understand effect of porosity, vesicular and amygdular basaltic flows collected from central and west-central India were investigated for these engineering properties and correlated with apparent porosity of core samples. It is observed that a good level of correlation is obtained for uniaxial compressive strength (UCS), elastic modulus (E) and Poisson’s ratio in vesicular basalts when porosity >8-10%. In case of Brazilian strengths a linearly downward trend is observed with the increase in porosity values. And, no significant correlation is observed for waves’ velocities in both variants of basalts. Keywords—apparen...
Geotechnical investigation of geomaterials is one of the most important tools to arrive at safe a... more Geotechnical investigation of geomaterials is one of the most important tools to arrive at safe and economical design of structures. Inadequate investigations many times result in non-optimal geotechnical solutions. Encounterence of geological surprises and adverse geological occurrences result in cost overrun and sometimes even compromising safety of the structures. The Himalayan Mountains in Northeast India are quite young and have a large potential for hydroelectric projects. Since this area lies in seismic Zone IV, earth and rockfill dams are more suitable in this region due to flexibility of the materials and capacity to absorb vibrations. In the present study, 135 m high earth and rockfill dam at Tlawng H. E. Project, Aizwal, Mizoram, has been considered across river Tlawng. Three potential borrow area locations were identified near the dam site to meet the requirement of impervious material for clay core of the dam. Representative soil samples were collected from the respecti...
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