The performance of a helical soil nailed structure is dependent on the installation torque required and the consequent pullout resistance developed.The present research work aims at proposing theoretical models to est...The performance of a helical soil nailed structure is dependent on the installation torque required and the consequent pullout resistance developed.The present research work aims at proposing theoretical models to estimate the required torque during installation of helical soil nails.Moreover,theoretical models are also developed to predict the pullout capacity of single and group of the helical nail for uniform and staggered arrangements.The proposed model predicts the pure-elastic and elastic-plastic pullout behavior of different helical nails.An equation for estimating the capacity-totorque Ratio(Kt)has also been developed for different nail shaft diameters.The results from the proposed models are validated with experimental results obtained from model testing of both single and group of helical nails.The predicted results are also compared for validation with the published literature.The results for installation torque and pullout load depict that the developed models predict values which are in accordance with the experimental results and are also found in good agreement with the published literature.Thus,the proposed models can effectively be used by the filed engineers for estimating the required installation torque and corresponding pullout capacities for single or double plate helical soil nails in cohesionless soil under surcharge pressure range of 0–50k Pa.展开更多
This paper presents the effect of open dumping of municipal solid waste(MSW) on soil characteristics in the mountainous region of Himachal Pradesh, India. The solid waste of dumpsite contains various complex character...This paper presents the effect of open dumping of municipal solid waste(MSW) on soil characteristics in the mountainous region of Himachal Pradesh, India. The solid waste of dumpsite contains various complex characteristics with organic fractions of the highest proportions. As leachate percolates into the soil, it migrates contaminants into the soil and affects soil stability and strength. The study includes the geotechnical investigation of dump soil characteristics and its comparison with the natural soil samples taken from outside the proximity of dumpsites. The geochemical analysis of dumpsite soil samples was also carried out by scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS).Visual inspection revealed that the MSW consists of high fraction of organics, followed by paper. The soil samples were collected from five trial pits in the dumpsites at depths of 0.5 m, 1 m and 1.5 m. Then the collected soil samples were subjected to specific gravity test, grain size analysis, Atterberg’s limit test,compaction test, direct shear test, California bearing ratio(CBR) test and permeability analysis. The study indicated that the dumpsite soils from four study regions show decreasing trends in the values of maximum dry density(MDD), specific gravity, cohesion and CBR, and increasing permeability as compared to the natural soil. The results show that the geotechnical properties of the soils at all four study locations have been severely hampered due to contamination induced by open dumping of waste.展开更多
An investigation into the pullout response of helical soil nail using finite element subroutine Plaxis 2D is presented.The numerical modelling of actual pullout response is achieved by axisymmetric and horizontal load...An investigation into the pullout response of helical soil nail using finite element subroutine Plaxis 2D is presented.The numerical modelling of actual pullout response is achieved by axisymmetric and horizontal loading condition.The effect of varying number of helical plates,helical plate spacing and helical plate diameter is studied to understand the pullout capacity behaviour.The failure surfaces for various helical soil nail configurations and their pullout mechanisms are also analysed and discussed.The pullout capacity is found to increase with increase in number of helical plates.The helical plate spacing ratio（s/D;） and diameter ratio（D;/D;） are found to increase the pullout only up to a critical value.The response of helical soil nail using axisymmetric finite element simulation is found similar to the uplift behaviour of helical piles and helical soil anchors.In the absence of literature regarding numerical modelling of helical soil nail,simulation results are validated with uplift responses of helical piles and soil anchors.A good agreement in their comparative study for pullout response is also observed.展开更多
Rockfill dams are mostly constructed using blasted rockfill materials obtained by blasting rocks or alluvial rockfill materials collected from the riverbeds. Behaviors of rockfill materials and their characterization ...Rockfill dams are mostly constructed using blasted rockfill materials obtained by blasting rocks or alluvial rockfill materials collected from the riverbeds. Behaviors of rockfill materials and their characterization signifcantly depend on breakage factor observed during triaxial loading. In this paper, two modeled rockfill materials are investigated by using medium triaxial cell. Drained triaxial tests are conducted on various sizes of modeled rockfill materials used in the two dams, and test data are analyzed accordingly. Breakage factor of rockfill material is studied and the effects of particle size and confining pressure on breakage factor are investigated using medium triaxial cell as many researchers have already conducted investigation using large triaxial cell.展开更多
An internal failure mode for a soil-nailed system consists of failure at nail heads,slope facing,nail strength,along groutesoil interface and pullout failure.A better understanding of pullout of soil nail thus becomes...An internal failure mode for a soil-nailed system consists of failure at nail heads,slope facing,nail strength,along groutesoil interface and pullout failure.A better understanding of pullout of soil nail thus becomes important to assess the stability of a soil-nailed system.In the present study,an investigation into the pullout behaviour of soil nail with circular discs along the shaft has been carried out by a threedimensional finite element analysis using Abaqus/Explicit routine.A total of 67 simulations have been performed to accurately predict the pullout behaviour of soil nail.The soil nail under study has circular discs along its shaft varying in numbers from 1 to 4.The pullout of this soil nail in a pullout test box has been simulated with a constant overburden pressure of 20 kPa acting on the nail.The pullout load edisplacement characteristics,stresses around soil nail and failure mechanism during pullout are studied.Variations of dimensionless factors such as normalised pullout load factor and bearing capacity factor have been obtained with different combinations of parameters in terms of relative disc spacing ratio,anchorage length ratio,embedment ratio,diameter ratio and displacement ratio.From the results of analyses,it is found that nail with more circular discs requires higher pullout load.There are critical relative disc spacing ratio and diameter ratio which significantly affect the pullout behaviour of nail.展开更多
Objective:To assess the hepatoprotective effct of Ipomoea carnea(I.carrnea)extract against antitubercular drug-induced liver toxicity in experimental animals.Methods:I.carnea extracts(125,250 and 500 mg/kg,p.o.body we...Objective:To assess the hepatoprotective effct of Ipomoea carnea(I.carrnea)extract against antitubercular drug-induced liver toxicity in experimental animals.Methods:I.carnea extracts(125,250 and 500 mg/kg,p.o.body weight)were administered daily for 35 d in experimental animals.Liver toxicity was induced by combination of three antitubercular drugs(isoniazid 7.5 mg/kg,rifampicin 10 mg/kg and pyrazinamide 35 mg/kg)given orally as suspension for 35 d in rats.Treatment groups received I.carnea extracts along with antitubercular drugs.The hepatoprotective activity was assessed using various biochemical parameters like aspartate aminotransferase,alanine aminotransferase,alkaline phosphatise and total bilirubin.Meanwhile,in-vivo antioxidant activities as lipid peroxidation,reduced glutathione,superoxide dismutase and catalase were measured in rat liver homogenate along with ATPase and G-6-Pase.The biochemical observations were supplemented by histopathological examination.Results:Obtained results demonstrated that treatment with I.carnea extracts significantly(P<0.05-P<0.001)and dose-dependently prevented drug induced increase in serum levels of hepatic enzymes.Furthermore,I.carnea extracts significantly(up to P<0.001)reduced the lipid peroxidation in the liver tissue and restored activities of defence antioxidant enzymes,reduced glutathione,superoxide dismutase and catalase towards normal levels.Histopathology of the liver tissue showed that I.carnea extracts attenuated the hepatocellular necrosis,massive fatty changes and led to reduction in inflammatory cells infiltration.Conclusions:The results of this study strongly indicate the protective effect of I.carnea extracts against liver injury,which may be attributed to its hepatoprotective activity,and there by scientifically support its traditional use.展开更多
文摘The performance of a helical soil nailed structure is dependent on the installation torque required and the consequent pullout resistance developed.The present research work aims at proposing theoretical models to estimate the required torque during installation of helical soil nails.Moreover,theoretical models are also developed to predict the pullout capacity of single and group of the helical nail for uniform and staggered arrangements.The proposed model predicts the pure-elastic and elastic-plastic pullout behavior of different helical nails.An equation for estimating the capacity-totorque Ratio(Kt)has also been developed for different nail shaft diameters.The results from the proposed models are validated with experimental results obtained from model testing of both single and group of helical nails.The predicted results are also compared for validation with the published literature.The results for installation torque and pullout load depict that the developed models predict values which are in accordance with the experimental results and are also found in good agreement with the published literature.Thus,the proposed models can effectively be used by the filed engineers for estimating the required installation torque and corresponding pullout capacities for single or double plate helical soil nails in cohesionless soil under surcharge pressure range of 0–50k Pa.
文摘This paper presents the effect of open dumping of municipal solid waste(MSW) on soil characteristics in the mountainous region of Himachal Pradesh, India. The solid waste of dumpsite contains various complex characteristics with organic fractions of the highest proportions. As leachate percolates into the soil, it migrates contaminants into the soil and affects soil stability and strength. The study includes the geotechnical investigation of dump soil characteristics and its comparison with the natural soil samples taken from outside the proximity of dumpsites. The geochemical analysis of dumpsite soil samples was also carried out by scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS).Visual inspection revealed that the MSW consists of high fraction of organics, followed by paper. The soil samples were collected from five trial pits in the dumpsites at depths of 0.5 m, 1 m and 1.5 m. Then the collected soil samples were subjected to specific gravity test, grain size analysis, Atterberg’s limit test,compaction test, direct shear test, California bearing ratio(CBR) test and permeability analysis. The study indicated that the dumpsite soils from four study regions show decreasing trends in the values of maximum dry density(MDD), specific gravity, cohesion and CBR, and increasing permeability as compared to the natural soil. The results show that the geotechnical properties of the soils at all four study locations have been severely hampered due to contamination induced by open dumping of waste.
文摘An investigation into the pullout response of helical soil nail using finite element subroutine Plaxis 2D is presented.The numerical modelling of actual pullout response is achieved by axisymmetric and horizontal loading condition.The effect of varying number of helical plates,helical plate spacing and helical plate diameter is studied to understand the pullout capacity behaviour.The failure surfaces for various helical soil nail configurations and their pullout mechanisms are also analysed and discussed.The pullout capacity is found to increase with increase in number of helical plates.The helical plate spacing ratio（s/D;） and diameter ratio（D;/D;） are found to increase the pullout only up to a critical value.The response of helical soil nail using axisymmetric finite element simulation is found similar to the uplift behaviour of helical piles and helical soil anchors.In the absence of literature regarding numerical modelling of helical soil nail,simulation results are validated with uplift responses of helical piles and soil anchors.A good agreement in their comparative study for pullout response is also observed.
文摘Rockfill dams are mostly constructed using blasted rockfill materials obtained by blasting rocks or alluvial rockfill materials collected from the riverbeds. Behaviors of rockfill materials and their characterization signifcantly depend on breakage factor observed during triaxial loading. In this paper, two modeled rockfill materials are investigated by using medium triaxial cell. Drained triaxial tests are conducted on various sizes of modeled rockfill materials used in the two dams, and test data are analyzed accordingly. Breakage factor of rockfill material is studied and the effects of particle size and confining pressure on breakage factor are investigated using medium triaxial cell as many researchers have already conducted investigation using large triaxial cell.
文摘An internal failure mode for a soil-nailed system consists of failure at nail heads,slope facing,nail strength,along groutesoil interface and pullout failure.A better understanding of pullout of soil nail thus becomes important to assess the stability of a soil-nailed system.In the present study,an investigation into the pullout behaviour of soil nail with circular discs along the shaft has been carried out by a threedimensional finite element analysis using Abaqus/Explicit routine.A total of 67 simulations have been performed to accurately predict the pullout behaviour of soil nail.The soil nail under study has circular discs along its shaft varying in numbers from 1 to 4.The pullout of this soil nail in a pullout test box has been simulated with a constant overburden pressure of 20 kPa acting on the nail.The pullout load edisplacement characteristics,stresses around soil nail and failure mechanism during pullout are studied.Variations of dimensionless factors such as normalised pullout load factor and bearing capacity factor have been obtained with different combinations of parameters in terms of relative disc spacing ratio,anchorage length ratio,embedment ratio,diameter ratio and displacement ratio.From the results of analyses,it is found that nail with more circular discs requires higher pullout load.There are critical relative disc spacing ratio and diameter ratio which significantly affect the pullout behaviour of nail.
基金Supported by Luqman College of Pharmacy,Gulbarga,Karnataka,(Grant No-LCP/GC/09).
文摘Objective:To assess the hepatoprotective effct of Ipomoea carnea(I.carrnea)extract against antitubercular drug-induced liver toxicity in experimental animals.Methods:I.carnea extracts(125,250 and 500 mg/kg,p.o.body weight)were administered daily for 35 d in experimental animals.Liver toxicity was induced by combination of three antitubercular drugs(isoniazid 7.5 mg/kg,rifampicin 10 mg/kg and pyrazinamide 35 mg/kg)given orally as suspension for 35 d in rats.Treatment groups received I.carnea extracts along with antitubercular drugs.The hepatoprotective activity was assessed using various biochemical parameters like aspartate aminotransferase,alanine aminotransferase,alkaline phosphatise and total bilirubin.Meanwhile,in-vivo antioxidant activities as lipid peroxidation,reduced glutathione,superoxide dismutase and catalase were measured in rat liver homogenate along with ATPase and G-6-Pase.The biochemical observations were supplemented by histopathological examination.Results:Obtained results demonstrated that treatment with I.carnea extracts significantly(P<0.05-P<0.001)and dose-dependently prevented drug induced increase in serum levels of hepatic enzymes.Furthermore,I.carnea extracts significantly(up to P<0.001)reduced the lipid peroxidation in the liver tissue and restored activities of defence antioxidant enzymes,reduced glutathione,superoxide dismutase and catalase towards normal levels.Histopathology of the liver tissue showed that I.carnea extracts attenuated the hepatocellular necrosis,massive fatty changes and led to reduction in inflammatory cells infiltration.Conclusions:The results of this study strongly indicate the protective effect of I.carnea extracts against liver injury,which may be attributed to its hepatoprotective activity,and there by scientifically support its traditional use.
