Landslides triggered by heavy rainfall pose a serious threat globally, endangering infrastructure and lives. Many previous landslide studies lack comprehensiveness and site specificity. Thus, a comprehensive investiga...Landslides triggered by heavy rainfall pose a serious threat globally, endangering infrastructure and lives. Many previous landslide studies lack comprehensiveness and site specificity. Thus, a comprehensive investigation is essential to understand the failure mechanisms and contributing factors for assessing potential future hazards. This study aims to investigate the debris flow landslide that occurred in Kavalappara, Kerala, India, on August 8, 2019, through an integrated approach combining geophysical test, weathering characterization, geotechnical, and numerical analyses. Shear wave velocity(V_s) was determined using the Multi-Channel Analysis of Surface Waves(MASW) test to obtain the substrata of the slope. Residual and unsaturated soil properties were obtained through ring shear and dew point potentiometer tests. The mineralogical composition of the soil was identified using Field-Emission Scanning Electron Microscopy(FE-SEM), Energy Dispersive XRay Analysis(EDAX), and X-Ray Diffraction(XRD) patterns. These investigation results focused on slope stability during rainfall infiltration using Limit Equilibrium(LEM) and Finite Element Analysis(FEM) for both low and high-intensity rainfall. Finally, the progressive failure mechanism of the landslide was analysed using the Finite Difference program(FDM). The soil profile showed a variation from loose to dense, with a V_s range of 172.85 m/s to 440.53 m/s. No rock layers were identified down to a depth of 15 m. The landslide area consists of migmatite as a parent rock, and the soil was identified as silty clay, comprising quartz and clay minerals. The FEM and LEM analyses reveal that the factor of safety was reduced to 0.83 due to increased pore water pressure and the degree of saturation. The pore water pressure ratio(r_u), estimated at 0.32, was used in the FDM. The landslide, initiated at r_u of 0.35, reached maximum velocities of 15.4 m/s horizontally and 12.4 m/s vertically. This study helps disaster management to analyse debris flow and find effective mitigation strategies for hilly areas.展开更多
Natural damming of rivers by mass movements is a very common and potentially dangerous phenomena which has been documented all over the world. In this paper, a two-layer model of Savage-Hutter type is presented to sim...Natural damming of rivers by mass movements is a very common and potentially dangerous phenomena which has been documented all over the world. In this paper, a two-layer model of Savage-Hutter type is presented to simulate the dynamic procedure for the intrusion of landslide into rivers. The two-layer shallow water system is derived by depth averaging the incompressible Navier-Stokes equations with the hydrostatic assumption. A high order accuracy scheme based on the finite volume method is proposed to solve the presented model equations. Several numerical tests are performed to verify the realiability and feasibility of the proposed model. The numerical results indicate that the proposed method can be competent for simulating the dynamic process of landslide intrusion into the river. The interaction effect between both layers has a significant impact on the landslide movement, water fluctuation and wave propagation.展开更多
This paper focuses on the analytical derivation and the numerical simulation analyses to predict the interaction influences between a landslide and a new tunnel in mountain areas. Based on the slip-line theory, the di...This paper focuses on the analytical derivation and the numerical simulation analyses to predict the interaction influences between a landslide and a new tunnel in mountain areas. Based on the slip-line theory, the disturbance range induced by tunneling and the minimum safe distance between the tunnel vault and the sliding belt are obtained in consideration of the mechanical analyses of relaxed rocks over the tunnel opening. The influence factors for the minimum safe crossing distance are conducted,including the tunnel radius, the friction angle of surrounding rocks, the inclination angle of sliding belt,and the friction coefficient of surrounding rocks. Secondly, taking account of the compressive zone and relaxed rocks caused by tunneling, the Sarma method is employed to calculate the safety factor of landslide. Finally, the analytical solutions for interaction between the tunnel and the landslide are compared with a series of numerical simulations, considering the cases for different perpendicular distances between the tunnel vault and the sliding belt. Resultsshow that the distance between the tunnel vault and the slip zone has significant influence on the rock stress and strain. For the case of the minimum crossing distance, a plastic zone in the landslide traversed by tunneling would be formed with rather large range, which seriously threatens the stability of landslide. This work demonstrates that the minimum safe crossing distance obtained from numerical simulation is in a good agreement with that calculated by the proposed analytical solutions.展开更多
Based on analysis and simulation,the interaction of thermal forcing between the Tibetan Plateau(TP) and Iranian Plateau(IP) in summer is investigated.Associated influences on water vapor transport in the Asian subtrop...Based on analysis and simulation,the interaction of thermal forcing between the Tibetan Plateau(TP) and Iranian Plateau(IP) in summer is investigated.Associated influences on water vapor transport in the Asian subtropical monsoon region and the formation of a cold center in the lower stratosphere over Eurasia are also investigated.Results show that surface sensible heating(SH) over the two plateaus not only have mutual influences but also feedback to each other.SH over the IP can reduce the SH and increase the LH over the TP,whereas the SH over the TP can increase surface heating over the IP,thereby reaching quasi-equilibrium among the SH and LH over the TP,IP SH and atmosphere vertical motion.Therefore,the so-called Tibetan-Iranian Plateau coupling system(TIPS) is constructed,which influences atmosphere circulation.In the TIPS system,interaction between surface SH and LH over the TP plays a leading role.SH of the IP and TP influences on other regions not only have superimposed effects but also mutually offset.Accounting for contributions to the convergence of water vapor transport in the Asian subtropical monsoon region,TP SH contributes more than twice that of the IP.The combined influence of SH over TP and IP represents the major contribution to the convergence of water vapor transport in that region.In addition,the heating effect of TIPS increases the upper tropospheric temperature maximum and lifts the tropopause,cooling the lower stratosphere.Combined with large-scale thermal forcing of the Eurasian continent,the TIPS produces a strong anticyclonic circulation and the South Asian High that warms the upper troposphere and cools the lower stratosphere,thereby affecting regional and global weather and climate.展开更多
文摘Landslides triggered by heavy rainfall pose a serious threat globally, endangering infrastructure and lives. Many previous landslide studies lack comprehensiveness and site specificity. Thus, a comprehensive investigation is essential to understand the failure mechanisms and contributing factors for assessing potential future hazards. This study aims to investigate the debris flow landslide that occurred in Kavalappara, Kerala, India, on August 8, 2019, through an integrated approach combining geophysical test, weathering characterization, geotechnical, and numerical analyses. Shear wave velocity(V_s) was determined using the Multi-Channel Analysis of Surface Waves(MASW) test to obtain the substrata of the slope. Residual and unsaturated soil properties were obtained through ring shear and dew point potentiometer tests. The mineralogical composition of the soil was identified using Field-Emission Scanning Electron Microscopy(FE-SEM), Energy Dispersive XRay Analysis(EDAX), and X-Ray Diffraction(XRD) patterns. These investigation results focused on slope stability during rainfall infiltration using Limit Equilibrium(LEM) and Finite Element Analysis(FEM) for both low and high-intensity rainfall. Finally, the progressive failure mechanism of the landslide was analysed using the Finite Difference program(FDM). The soil profile showed a variation from loose to dense, with a V_s range of 172.85 m/s to 440.53 m/s. No rock layers were identified down to a depth of 15 m. The landslide area consists of migmatite as a parent rock, and the soil was identified as silty clay, comprising quartz and clay minerals. The FEM and LEM analyses reveal that the factor of safety was reduced to 0.83 due to increased pore water pressure and the degree of saturation. The pore water pressure ratio(r_u), estimated at 0.32, was used in the FDM. The landslide, initiated at r_u of 0.35, reached maximum velocities of 15.4 m/s horizontally and 12.4 m/s vertically. This study helps disaster management to analyse debris flow and find effective mitigation strategies for hilly areas.
基金Financial support from the National Science Fund for Distinguished Young Scholars (Grant No.41225011)the NSFC (Grant No. 41272346)+1 种基金the Information technology project of the Department of transportation (2014364J03090)the STS project of Chinese Academy of Sciences (project No. KFJ-EW-STS-094)
文摘Natural damming of rivers by mass movements is a very common and potentially dangerous phenomena which has been documented all over the world. In this paper, a two-layer model of Savage-Hutter type is presented to simulate the dynamic procedure for the intrusion of landslide into rivers. The two-layer shallow water system is derived by depth averaging the incompressible Navier-Stokes equations with the hydrostatic assumption. A high order accuracy scheme based on the finite volume method is proposed to solve the presented model equations. Several numerical tests are performed to verify the realiability and feasibility of the proposed model. The numerical results indicate that the proposed method can be competent for simulating the dynamic process of landslide intrusion into the river. The interaction effect between both layers has a significant impact on the landslide movement, water fluctuation and wave propagation.
基金financial support provided by Natural Science Foundation of China (Grant No. 51008188)by Shanghai Natural Science Foundation (Grant No. 15ZR1429400)+2 种基金by Open Project Program of State Key Laboratory Breeding Base of Mountain Bridge and Tunnel Engineering (Grant No. CQSLBF-Y15-1)by Open Project Program of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Grant No. SKLGP2015K015)by the Open Project Program of Key Laboratory of Geohazard Prevention of Hilly Mountains, Ministry of Land and Resources (Grant No. 2015k005)
文摘This paper focuses on the analytical derivation and the numerical simulation analyses to predict the interaction influences between a landslide and a new tunnel in mountain areas. Based on the slip-line theory, the disturbance range induced by tunneling and the minimum safe distance between the tunnel vault and the sliding belt are obtained in consideration of the mechanical analyses of relaxed rocks over the tunnel opening. The influence factors for the minimum safe crossing distance are conducted,including the tunnel radius, the friction angle of surrounding rocks, the inclination angle of sliding belt,and the friction coefficient of surrounding rocks. Secondly, taking account of the compressive zone and relaxed rocks caused by tunneling, the Sarma method is employed to calculate the safety factor of landslide. Finally, the analytical solutions for interaction between the tunnel and the landslide are compared with a series of numerical simulations, considering the cases for different perpendicular distances between the tunnel vault and the sliding belt. Resultsshow that the distance between the tunnel vault and the slip zone has significant influence on the rock stress and strain. For the case of the minimum crossing distance, a plastic zone in the landslide traversed by tunneling would be formed with rather large range, which seriously threatens the stability of landslide. This work demonstrates that the minimum safe crossing distance obtained from numerical simulation is in a good agreement with that calculated by the proposed analytical solutions.
基金supported by the National Natural Science Foundation of China(Grant Nos.91437219&91637312)the Special Fund for Public Welfare Industry(Meteorology)administered by the Chinese Ministry of Finance and the Ministry of Science and Technology(Grant No.GYHY201406001)+2 种基金the China Postdoctoral Science Foundation(Grant No.2016M600695)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDY-SSWDQC018)the Special Program for Applied Research on Super Computation of the National Natural Science Foundation of China-Guangdong Joint Fund(The Second Phase)
文摘Based on analysis and simulation,the interaction of thermal forcing between the Tibetan Plateau(TP) and Iranian Plateau(IP) in summer is investigated.Associated influences on water vapor transport in the Asian subtropical monsoon region and the formation of a cold center in the lower stratosphere over Eurasia are also investigated.Results show that surface sensible heating(SH) over the two plateaus not only have mutual influences but also feedback to each other.SH over the IP can reduce the SH and increase the LH over the TP,whereas the SH over the TP can increase surface heating over the IP,thereby reaching quasi-equilibrium among the SH and LH over the TP,IP SH and atmosphere vertical motion.Therefore,the so-called Tibetan-Iranian Plateau coupling system(TIPS) is constructed,which influences atmosphere circulation.In the TIPS system,interaction between surface SH and LH over the TP plays a leading role.SH of the IP and TP influences on other regions not only have superimposed effects but also mutually offset.Accounting for contributions to the convergence of water vapor transport in the Asian subtropical monsoon region,TP SH contributes more than twice that of the IP.The combined influence of SH over TP and IP represents the major contribution to the convergence of water vapor transport in that region.In addition,the heating effect of TIPS increases the upper tropospheric temperature maximum and lifts the tropopause,cooling the lower stratosphere.Combined with large-scale thermal forcing of the Eurasian continent,the TIPS produces a strong anticyclonic circulation and the South Asian High that warms the upper troposphere and cools the lower stratosphere,thereby affecting regional and global weather and climate.
