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simulation of landslide run-out by considering frictional heating and thermal pressurization

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Journal of Mountain Science 2019年第1期16卷 122-137页

作者： LIU Wei he si-ming he Zi-lu Key Laboratory of Mountain Hazards and Surface Process Chinese Academy of Science Institute of Mountain Hazards and Environment Chinese Academy of Sciences CAS Center for Excellence in Tibetan Plateau Earth Sciences Department of Applied Mechanics and Engineering Southwest Jiaotong University

Some of the remarkable characteristics of natural landslides, such as surprisingly long travel distances and high velocities, have been attributed to the mechanisms of frictional heating and thermal pressurization. In this work, this mechanism is combined with a depth-averaged model to simulate the long runout of landslides in the condition of deformation. Some important factors that influence frictional heating and thermal pressurization within the shear zone are further considered, including velocity profile and pressurization coefficient. In order to solve the coupled equations, a combined computational method based on the finite volume method and quadratic upwind interpolation for convective kinematics scheme is proposed. Several numerical tests are performed to demonstrate the feasibility of the computational scheme, the influence of thermal pressurization on landslide run-out, and the potential of the model to simulate an actual landslide.

关键词： Landslide Frictional heating Thermal pressurization Numerical simulation

Dynamic process simulation with a Savage-Hutter type model for the intrusion of landslide into river

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Journal of Mountain Science 2016年第7期13卷 1265-1274页

作者： LIU Wei he si-ming Ou Yang Chao-jun Key laboratory of Mountain Hazards and Surface Process Chinese Academy of Science Institute of Mountain Hazards and Environment Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of Sciences

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.

关键词： Landslide Two-layer model Savage Hutter type Numerical simulation

Field investigation and numerical simulation on rockfalls in Zhangmu Town, Tibet, China

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Journal of Mountain Science 2022年第3期19卷 740-755页

作者： WANG Zhong-fu LIU Han-dong he si-ming BI Dan North China University of Water Resources and Electric Power Zhengzhou 450046China henan Key Laboratory of Geotechnical and Structure Engineering Zhengzhou 450046China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China China Liaohe Petroleum Engineering co. LTDPanjin124010China

Zhangmu Town in Tibet of China,which lies in the southern piedmont of the median Himalayas,is a small but strategically important port of trade exchange between China and *** rockfall events have occurred in Zhangmu since 1970,resulting in huge economic losses and serious influence on the bilateral *** conducted a detailed field investigation on the high and steep slope in Zhangmu Town,and analyzed the distribution features,stability,failure modes and evolution of dangerous rocks of potential *** we numerically simulated the movement path,velocity and accumulation forms of the rockfall with PFC^(3D) *** results indicated that the dangerous rock belt could be divided into three sections,namely,unstable section,slightly stable section and basically stable *** was estimated that the rock debris and single dangerous rock would be unstable in the case of earthquakes or *** to the terrain constraints,the fallen rocks would scatter near the mouth of the Zhangmu ditch and in the Buqu River through multiple times of rolling,collision-induced diversion and *** reinforcement,the rockfall could cause serious damage to the car parks,gas stations and National Highway 318 along the line from Zhangmu Town to Zhangmu *** on the field survey and numerical simulation,we recommended rockfall removal and interception as the major prevention measures,and protective sheds as auxiliary measure.

关键词： Rockfalls Failure mode Stability analysis Numerical simulation Micro parameters Prevention measures

Dynamic response and optimization of an inclined steel rock shed by the graded energy dissipating method

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Journal of Mountain Science 2019年第1期16卷 138-152页

作者： WU Yong he si-ming LI Xin-po Wang Dong-po Key Laboratory of Mountain Hazards and Earth Surface Process Chinese Academy of Sciences Institute of Mountain Hazards and Environment Chinese Academy of Sciences State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology

Blocking rockfalls directly by reinforced concrete(RC) flat sheds with thick sand cushions is an outdated method. Such conventional sheds typically accumulate rock heavily, and become progressively damaged and are difficult to repair, and are very costly. To address these problems, we propose a new structure called a Graded Dissipating Inclined Steel Rock(GDISR) shed that utilizes the graded energy dissipation method. here, we study the dynamic response of the GDISR shed with model test and numerical simulation, and give its optimization design combining with a practical engineering case. Our results show that the optimized modular E-block and corrugated steel tube can deform to sufficiently absorb the energy of different impact intensities. This efficiently and economically provides GDISR sheds with two security lines. Compared with conventional RC sheds, GDISR sheds with optimal incline have a more efficient anti-impact function, are faster and easier to repair, and are much simpler and cheaper to build.

关键词： Dynamic response Optimization design Graded dissipating inclined steel rock shed

A Generalized Limit Equilibrium Method for the Solution of Active Earth Pressure on a Retaining Wall

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Journal of Mountain Science 2013年第6期10卷 1018-1027页

作者： OUYANG Chao-jun XU Qiang he si-ming LUO Yu WU Yong Key laboratory of Mountain Hazards and Surface Process Chinese Academy of Sciences Institute of Mountain Hazards and Environment (IMhe) Chinese Academy of Sciences State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology

In this paper, a generalized limit equilibrium method of solving the active earth pressure problem behind a retaining wall is *** from other limit equilibrium methods, an arbitrary slip surface shape without any assumptions of pre-defined shapes is needed in the current framework, which is verified to find the most probable failure slip surface. Based on the current computational framework, numerical comparisons with experiment, discrete element method and other methods are carried out. In addition, the influences of the inclination of the wall, the soil cohesion, the angle of the internal friction of the soil, the slope inclination of the backfill soil on the critical pressure coefficient of the soil, the point of application of the resultant earth pressure and the shape of the slip surface are also carefully investigated. The results demonstrate that limit equilibrium solution from predefined slip plane assumption, including Coulomb solution, is a special case of current computational framework. It is well illustrated that the current method is feasible to evaluate the characteristics of earth pressure problem.

关键词： Limit equilibrium method Retainingwall Active earth pressure Critical slip surface

Hydro-mechanical analysis of rainfall-induced fines migration process within unsaturated soils

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Journal of Mountain Science 2017年第12期14卷 2603-2619页

作者： LEI Xiao-qin YANG Zong-ji he si-ming LIU En-long WONG henry LI Xin-po Key Laboratory of Mountain Hazards and Earth Surface Process Institute of Mountain Hazards and EnvironmentChinese Academy of Sciences College of Water Resource & Hydropower Sichuan University Center for Excellence in Tibetan Plateau Earth Sciences CAS Laboratoire de Génie Civil et Batiment Ecole Nationale des Travaux Publics de l’Etat Université de Lyon

Seepage-induced fines migration under rainfall infiltration is a main cause leading to shallow failures in loose colluvial slopes. To describe the full process of fines migration within unsaturated soils during rainfall infiltration and the associated hydromechanical behaviors, a seepage-erosion-deformation coupled formulation is proposed in this paper. The governing equations proposed are implemented into a finite element code and used to investigate the influences of skeleton deformation on the rainfall infiltration process through unsaturated soil *** numerical results were presented in detail for a better understanding of the rainfall-induced fines migration process within unsaturated soils. Further,the obtained results are integrated into an infinite slope model for slope stability analysis. The results show that, the skeleton deformation will affect the rainfall infiltration rate and hence the timing of slope failures; meanwhile their influences are more evident if the fines deposition process is taken into ***, the slope stability could be reduced gradually due to the soil strength loss along with loss of fine particles. Therefore, particular attentions should be paid to analyzing the stability of soil slopes susceptible to internal erosion.

关键词： Rainfall infiltration Fines migration Internal erosion Seepage deformation Slope stability

Numerical investigation of effects of “baffles-deceleration strip” hybrid system on rock avalanches

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Journal of Mountain Science 2019年第2期16卷 414-427页

作者： BI Yu-zhang he si-ming DU Yan-jun SHAN Jie YAN Shuai-xing WANG Dong-po SUN Xin-po Institute of Geotechnical Engineering of Southeast University School of Transportation Southeast University Key Laboratory of Mountain Hazards and Surface Process Chinese Academy of Sciences Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chinese Academy of Sciences Center for Excellence in Tibet Plateau Earth Sciences University of Chinese Academy of Sciences State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology College of civil engineering Sichuan University of Science and Engineering

Arrays of baffles are usually installed in front of protection site to attenuate the flow energy of rock avalanches in mountainous areas. Optimization design is crucial for efficiency promotion in hazard energy dissipation engineering. In this study, a deceleration strip was added in the baffles protection system to optimize the traditional baffles system. The effects of the "baffles-deceleration strip" hybrid protection system was discussed in detail with the nails number and nails angle. This study presents details of numerical experiments using the discreteelement method(DEM). The effect of the optimization of hybrid protection system(nail angle and nail number) were investigated specifically, especially the impact force that avalanches exerted on structures. The results show that the maximum impact forces and kinetic energy of the rock avalanches decreases with the increase of the number and angle of the nail. Moreover, the distance between the toe and the bearing structure(L_m) is also a key factor. The shorter the distance L_m(30 m) is, the higher the maximum impact force are. The longer the distance L_m(70 m) is, the lower the maximum impact force are. Under the same size of the nails, increasing the numbers can enhance the dissipation ability of the hybrid protection system. Meanwhile, increasing itsangle can also enhance the dissipation ability. There are three key ways for nails attenuate rock avalanches:(i) block the fine particles directly;(ii) form the particles bridge between nails and baffles;(iii) dissipate the coarse particles energy directly. The effect of segregation in rock avalanches is crucial for the energy dissipation mechanism, which is a key factor to optimize the traditional baffle system.

关键词： Rock avalanches Baffles Hybrid system Energy dissipation Impact force

Geo-engineered buffer capacity of two-layered absorbing system under the impact of rock avalanches based on Discrete Element Method

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Journal of Mountain Science 2016年第5期13卷 917-929页

作者： BI Yu-zhang he si-ming LI Xin-po WU Yong XU Qiang OUYANG Chao-jun SU Li-Jun WANG Hao Key Laboratory of Mountain Hazards and Earth Surface Process Chinese Academy of Sciences Institute of Mountain Hazards and Environment Chinese Academy of Sciences & Water Resources Ministry Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of Sciences State Key Laboratory of Geo-Hazard Prevention and Geo-Environment Protection Chengdu University of Technology College of Environment and Resources Fuzhou University

Many rock avalanches were triggered by the Wenchuan earthquake on May 12, 2008 in southwest China. Protection galleries covered with a single soil layer are usually used to protect against rockfall. since one-layer protection galleries do not have sufficient buffer capacity, a two-layered absorbing system has been designed. This study aims to find whether an expanded poly-styrol （EPS） cushion, which is used in the soil-covered protection galleries for shock absorption, could be positioned under dynamic loadings. The dynamic impacts of the two-layered absorbing system under the conditions of rock avalanches are numerically simulated through a 2D discrete dement method. By selecting reasonable parameters, a series of numerical experiments were conducted to find the best combination for the two- layered absorbing system. The values of the EPS layer area as a percentage of the total area were set as 0% （Sl）, 22~ （S2）, and 70% （$3）. 22~ of the area of the EPS layer was found to be a reasonable value, and experiments were conducted to find the best position of the EPS layer in the two-layered absorbing system. The numerical results yield useful conclusions regarding the interaction between the impacting avalanches and the two-layered absorbing system. The soil layer can absorb the shock energy effectively and S2 （0.4-m thick EPS cushion covered with soil layer） is the most efficient combination, which can reduce the impact force, compared with the other combinations.

关键词： Discrete element method Buffer capacity Dynamic simulation Impact force Two-layered absorbing system

Numerical modeling and dynamic analysis of the 2017 Xinmo landslide in Maoxian County, China

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Journal of Mountain Science 2017年第9期14卷 1701-1711页

作者： OUYANG Chao-jun ZHAO Wei he si-ming WANG Dong-po ZHOU Shu AN Hui-cong WANG Zhong-wen CheNG Duo-xiang Key laboratory of Mountain Hazards and Surface Process &Institute of Mountain Hazards and Environment (IMhe) Chinese Academy of Sciences Chengdu 610041 China University of Chinese Academy of Sciences Beijing 100049 China Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of Sciences Beijing 100101 China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology Chengdu 610o59 China sichuan Engineering Research Center for Emergency Mapping & Disaster Reduction/sichuan Geomatics Center Chengdu 610041 China

A catastrophic landslide occurred at Xinmo village in Maoxian County, sichuan Province,China, on June 24, 2017. A 2.87×106 m3 rock mass collapsed and entrained the surface soil layer along the landslide path. Eighty-three people were killed or went missing and more than 103 houses were destroyed. In this paper, the geological conditions of the landslide are analyzed via field investigation and high-resolution imagery. The dynamic process and runout characteristics of the landslide are numerically analyzed using a depth-integrated continuum method and Mac Cormack-TVD finite difference *** results show that the evaluated area of the danger zone matchs well with the results of field investigation. It is worth noting that soil sprayed by the high-speed blast needs to be taken into account for such kind of large high-locality landslide. The maximum velocity is about 55 m/s, which is consistent with most cases. In addition, the potential danger zone of an unstable block is evaluated. The potential risk area evaluated by the efficient depthintegrated continuum method could play a significant role in disaster prevention and secondary hazard avoidance during rescue operations.

关键词： Xinmo landslide Runout Numerical modeling Dynamic process Potential risk Highlocality landslide