Dynamic process of the Wenjiagou rock landslide in Sichuan Province,China

A rock avalanche is a geological event that is always sudden, rapid and with a long run-out, and can result in large loss of lives and property. The Wenjiagou rock avalanche was a high-speed rock landslide caused by a strong earthquake, in Mianzhu, Sichuan Province, southwest China. In this study, we reproduce the movement and deposition processes of the sliding mass by numerical simulation. We analyze the effects of the friction coefficient of each slip surface and the strength of the parallel bonds and contact stiffness between particles on the dynamic process and deposit features using three-dimensional particle flow code (PFC3D). The simulation results agree with the field measurements when the friction coefficient is 0.2, parallel bond strength is 2 MPa, and contact stiffness is 2?×?10⁸ kN/m. The landslide lasted about 115 s from the initial movement to the final deposition at the exit of the valley. The maximum velocity of the sliding mass was 114 m/s.     

Numerical modeling of the June 24, 2015, Hongyanzi landslide generated impulse waves in Three Gorges Reservoir,China

Subaerial landslides falling into confined water bodies often generate impulsive waves. Damaging landslide tsunamis in Three Gorges Reservoir, China, have struck several times in the last 15 years. On June 24, 2015, a 23?×?10⁴ m³ slope failure occurred on the east bank of the Daning River opposite Wushan Town. The sliding mass intruded into the Three Gorges Reservoir and initiated a reservoir tsunami that resulted in two deaths and significant damage to shipping facilities. A post-event survey revealed the landslide geometry and wave run-up distribution, while an eyewitness video captured most of the landslide motion. Employing these firm constraints, we applied the Tsunami Squares method to simulate the 2015 Hongyanzi landslide and tsunami. The simulation revealed that the landslide experienced a progressive failure in the first few seconds and impacted the water with a maximum velocity of ~?16 m/s. The initial wave propagated to the opposite shore in an arch shape, and the water surface reached a maximum amplitude of ~?11 m near the landslide. Wave amplitude-time curves at four points on the river cross section show that the initial wave reached Wushan town in about 50 s with an average wave velocity of ~?30 m/s. The maximum wave run-ups on the shoreline opposite the landslide are around 6 m and attenuate to less than 1 m beyond 2-km distance. The landslide simulation matches the observed geological profile and the eyewitness video, and the numerical results coincide with the observed wave run-up heights. Nearly 80% of landslide energy is lost due to frictional resistances, but the remaining fraction imparted to the tsunami carried catastrophic consequences to a large region. The numerical results emphasize the efficiency and accuracy of Tsunami Squares method for a “Quick Look” simulation of a potential landslide.     

考虑滑床摩擦弱化的大光包滑坡运动机制DDA数值模拟研究

2008年汶川发生M_S8.0级地震,此次地震触发了大约20万处滑坡,其中大光包滑坡是汶川地震触发的最大规模的滑坡,其复杂的高速远程运动机理引起了国内外学者的广泛关注。本文结合热分解及动态结晶将地震中断层间摩擦弱化机制(闪速加热导致热分解及粉末润滑)运用于大光包滑坡高速远程运动的模拟。本文通过修改非连续变形分析(DDA)程序中强度参数的输入方式,以基于速度变化的强度参数取代原DDA程序中的常数强度参数,进而实现了摩擦系数随接触两侧相对速度变化的动态调整。运用修改后的DDA对大光包滑坡的运动过程进行模拟。模拟结果表明滑床摩擦弱化是导致大光包滑坡高速远程运动特征的重要原因,修改后的DDA由于考虑了滑床摩擦弱化能够更加合理地模拟滑坡的高速远程运动特征,本文模拟的大光包滑坡在地震作用下失稳后,由于滑床摩擦弱化,更多的能量转化为动能,高速滑体掠过黄洞子沟后,爬上对面的平梁子,最终由于平梁子的“急刹车”作用,滑体停止运动。与修改前DDA相比,修改后的DDA对大光包滑坡运动过程和最终堆积形态的模拟结果与已有文献记载和野外调查结果相吻合。这也间接证明了大光包滑坡滑动过程中由于白云岩间摩擦闪速加热导致热分解及粉末润滑造成的摩擦系数降低,可能是造成大光包滑坡高速远程运动的重要原因。     

Volume,gravitational potential energy reduction,and regional centroid position change in the wake of landslides triggered by the 14 April 2010 Yushu earthquake of China

In recent years, earthquake-triggered landslides have attracted much attention in the scientific community as a main form of seismic ground response. However, little work has been performed concerning the volume and gravitational potential energy reduction of earthquake-triggered landslides and their severe effect on landscape change. This paper presents a quantitative study on the volume, gravitational potential energy reduction, and change in landscape related to landslides triggered by the 14 April 2010 Yushu earthquake. At least 2,036 landslides were triggered by the earthquake. A total landslide scar area of 1.194 km² was delineated from the visual interpretation of aerial photographs and satellite images and was supported by selected field checking. In this paper, we focus on possible answers to the following five questions: (1) What is the total volume of the 2,036 landslides triggered by the earthquake, and what is the average landslide erosion thickness in the earthquake-stricken area? (2) What are the elevations of all landslide materials in relation to pre- and post-landsliding? (3) How much was the gravitational potential energy reduced due to the sliding of these landslide materials? (4) What is the average elevation change caused by these landslides in the study area? (5) What is the vertical change of the regional centroid position above sea level, as induced by these landslides? It is concluded that the total volume of the 2,036 landslides is 2.9399?×?10⁶ m³. The landslide erosion thickness throughout the study area is 2.02 mm. The materials of these landslides moved from an elevation of 4,145.243 to 4,104.697 m, resulting in a decreased distance of 40.546 m. The gravitational potential energy reduction related to the landslides triggered by the earthquake was 2.9213?×?10¹² J. The average regional elevation of the study area is 4,427.160 m, a value consistent with the assumption that the accumulated materials were remained in situ. This value changes from 4,427.160 to 4,427.158 m with all landslide materials moved out of the study area, resulting in a reduction in elevation of 2 mm. Based on the assumption that all landslide materials moved out of the study area, the elevations of the centroid of the study area’s crust changed from 2,222.45967 to 2,222.45867 m, which means the centroid value decreased by 1 mm. This value is 0.001 mm when assuming that the materials were remained in situ, which is almost negligible, compared with the situation of “all landslide materials moved out of the study area.”     

Dynamic process analysis for the formation of Yangjiagou landslide-dammed lake triggered by the Wenchuan earthquake, China

The damming of rivers by landslides resulting in the formation of a lake was one of the typical secondary geological hazards triggered by the Wenchuan earthquake which occurred on May 12, 2008. Some landslide-dammed lakes were at a high risk of causing further damage since the rainstorm season was expected soon after the earthquake. Understanding the dynamic processes in the formation of landslide-dammed lakes is helpful in planning the mitigation measures. The Yangjiagou landslide-dammed lake was selected as a case study to investigate the typical processes of dam formation. The dynamic simulation of the formation of the Yangjiagou landslide-dammed lake was divided into two steps: the landslide step and the overflow/overtopping step. Two-dimensional discrete element method (DEM) was adopted to investigate the mechanics of the Yangjiagou landslide. The landslide process was found to be controlled by the bond strength and residual friction coefficient of the DEM models. Computational results show that the formation of the landslide dam took approximately 35 s. The maximum velocity of a typical particle was approximately 26.8 m/s. The shallow-water equation and finite difference method were used to analyze the hydrodynamic mechanisms of the overflow process of the landslide-dammed lake. Computational results show that overflow would have occurred 15.1 h after the river was blocked, and overtopping failure occurs for the landslide dam in the rainstorm season when the water flow is large enough, causing a major disaster.     

缓倾滑坡地质力学模型研究——以冯店滑坡为例

在国内外缓倾滑坡研究的基础上,从滑坡形成机制出发,建立缓倾滑坡地质力学模型,采用数字滑坡技术结合地面调查获取滑坡规模、滑动面倾角、后缘拉裂槽积水深度等参数,代入模型表达式可获得滑坡的临界摩擦系数,进而获取滑坡的总下滑力和总阻滑力。提出临界摩擦系数的概念及求取方法,临界摩擦系数与缓倾滑坡的易滑性（或稳定性）直接相关,分析表明滑坡的临界摩擦系数与滑体规模（滑动面长与宽）、滑动面倾角正相关,与滑体重量反相关,滑坡后壁倾角在60°-90°范围的变化对缓倾滑坡易滑性的影响很微弱。      

Vertical acceleration effect on landsides triggered by the Wenchuan earthquake,China

The 2008 Wenchuan earthquake with Ms8.0 triggered extensive throwing-pattern landslides in the area within or near the seismic faults. The resultant landslides from this earthquake brought to the fore the effect of vertical earthquake acceleration on landslide occurrence. The pseudostatic analysis and the dynamic response on landslide stability due to the Wenchuan earthquake are studied with the Chengxi (West Town) catastrophic landslide used as a case study. The results show that the epicenter distance is an important factor which affects the vertical acceleration and thus the stability of landslide. Also, the vertical acceleration was found to have a significant impact on the FOS of landslide if the earthquake magnitude is quite large. Within the seismic fault, the amplitude effect of vertical acceleration is very dominant with the FOS of landslide, for vertical acceleration ranging from positive to negative, having a variation of 25 %. The variation of FOS of landslide for vertical acceleration ranging from positive to negative are 15 and 5 % for landslides near seismic fault and outside seismic fault, respectively. For landslide with a slope angle <45°, the FOS of landslide with both horizontal and vertical accelerations is significantly greater than the one without vertical acceleration. Further, the results computed from both the pseudostatic method and dynamic analysis reveal that the FOS during the earthquake varied significantly whether vertical acceleration is considered or not. The results from this study explain why lots of throwing-pattern catastrophic landslides occurred within 10 km of the seismic fault in the Wenchuan earthquake.     

Analysis of waves generated by Gongjiafang landslide in Wu Gorge, three Gorges reservoir, on November 23, 2008

At 4:40p.m. on November 23, 2008, the Gongjiafang slope collapsed on the north bank of Yangtze River in Wu Gorge of Three Gorges Reservoir. The 380,000-m³ sliding mass consisted mainly of cataclastic rock. A video record of the major sliding incident was analyzed using the general laws of physical motion. The analysis indicated that the maximum speed and maximum acceleration of the sliding mass were 11.65?m/s and 2.23?m/s², respectively, and that the maximum amplitude and the propagation velocity of the water wave near the landslide were 31.8?m and 18.36?m/s, respectively. Wave run-up investigation indicated that the maximum run-up on shore was 13.1?m, which declined to 1.1?m at Wushan dock 4?km away. The incident causes no casualties, but did result in economic losses of RMB five million. The numerical simulation model GEOWAVE was used to simulate and reproduced the impulse wave generated by the landslide; the results were in good agreement with the observed incident. The numerical simulation data were then applied to analyze the decay and amplification effects of the landslide wave in the river course. The field investigations and witness information provide valuable materials for the studies of landslide kinematics and impulse waves generated by landslides. In addition, the research results provide a useful reference for future similar waves generated by landslides in reservoirs.     

堆载诱发型土质滑坡运动特征物质点法模拟

坡顶堆载是人类工程活动诱发滑坡的主因之一。物质点法（MPM）属于一种无网格数值计算方法,它能够有效模拟滑坡大变形全过程物质行为与运动特征。文章基于线性形函数离散方法、MUSL求解格式及Drucker-Prager屈服准则,建立了可用于滑坡全过程模拟的单套单相物质点模型;通过对比干燥铝棒堆积物模拟砂堆失稳过程的基准试验结果,对模型有效性进行了验证。对堆载诱发型土质滑坡典型工况进行了物质点法全过程模拟,获得了滑坡全过程中典型时刻坡体形态、塑性应变分布以及控制点滑速演化趋势。结果表明:算例堆载诱发型土质滑坡属推移型滑坡,具有渐进性破坏特征,可分为坡顶压缩、局部蠕滑、加速滑动与减速滑动等四个阶段。参数分析结果亦表明,堆载诱发型土质滑坡前缘物质运动特征量均与堆载量间存在强正相关性、而与土体黏聚力及内摩擦角存在强负相关性。统计29种典型工况,分别建立了峰值滑动加速度、最大滑速、最大滑距及坡体最大动能等运动特征量与堆载量、土体黏聚力及内摩擦角之间的线性回归方程,可用于堆载诱发型土质滑坡致灾行为预测。     

Dynamic process analysis for the initiation and movement of the Donghekou landslide-debris flow triggered by the Wenchuan earthquake

The Donghekou landslide-debris flow was a remarkable geological disaster triggered by the Wenchuan earthquake in 2008. The dynamic process of a rapid landslide-debris flow is very complicated and can be divided into two aspects: the slope dynamic response of the earthquake and the mass movement and accumulation process. A numerical method combined with a finite difference method (FDM) and discrete element method (DEM) for simulation of landslide-debris flow under seismic loading is presented. The FDM and DEM are coupled through the critical sliding surface, initiation time and velocity. The dynamic response of the slope is simulated by the finite difference method, and critical sliding surface is determined using the earthquake response spectrum method. The landslide initiation time and the velocity are determined by time–history analysis. The mass movement and accumulation process is simulated using the discrete element method. Simulation results demonstrate that the maximum amplification coefficient of dynamic acceleration for the Donghekou slope is approximately 3.909, the initiation time of landslide is approximately 6.0 s, and the average initial velocity of the sliding mass is approximately 0.85 m/s. The failure of the slope is the result of elevation-orientated amplification effect and the sliding mass triggered with a small initial velocity. The numerical simulated result of the maximum sliding velocity is approximately 66.35 m/s, and the mass is disintegrated rapidly because of collision and free fall. The landslide velocity decreases when the flowing mass reaches a lower slope angle and gradually comes to a stop, and the total travel distance is approximately 2400 m.     

Formation,failure, and consequences of the Xiaolin landslide dam,triggered by extreme rainfall from Typhoon Morakot,Taiwan

An extreme rainfall event on August 9, 2009, which was close to setting a world record for 48-h accumulated rainfall, induced the Xiaolin deep-seated landslide, which was located in southwestern Taiwan and had volume of 27.6?×?10⁶?m³, and caused the formation of a landslide dam. The landslide dam burst in a very short time, and little information remained afterward. We reconstructed the process of formation and failure of the Xiaolin landslide dam and also inferred the area of the impoundment and topographic changes. A 5?×?5-m digital elevation model, the recorded water stage of the Qishan River, and data from field investigation were used for analysis. The spectral magnitude of the seismic signals induced by the Xiaolin landslide and flooding due to failure of the landslide dam were analyzed to estimate the timing of the dam breach and the peak discharge of the subsequent flood. The Xiaolin landslide dam failure resulted from overtopping. We verified the longevity of the Xiaolin landslide dam at about 2 h relying on seismic signals and water level records. In addition, the inundated area, volume of the impoundment behind the Xiaolin landslide dam, and peak discharge of the flood were estimated at 92.3 ha, 19.5?×?10⁶?m³, and 17?×?10³?m³/s, respectively. The mean velocity of the flood-recession wave front due to the dam blockage was estimated at 28 km/h, and the peak flooding velocity after failure of the dam was estimated at 23 km/h. The Xiaolin landslide provides an invaluable opportunity for understanding the mechanism of deep-seated landslides and flooding processes following a landslide dam failure.     

The characteristics of the seismic signals induced by landslides using a coupling of discrete element and finite difference methods

Landslide seismic signals support researchers to estimate magnitudes and locations of landslides. They can serve as a crucial data for landslide warning systems. However, the randomness of landslide locations makes the acquisition of landslide-induced seismic signals difficult and limits the number of available field data. The objectives of this study are to establish a numerical modeling approach to examine the characteristics of seismic signals induced by landslides and perform parametrical study. The two-dimensional particle flow code (PFC) and Fast Lagrangian Analysis of Continua (FLAC) are coupled to simulate the landslide process. The force and velocity data at the coupled interfaces of FLAC and PFC are transferred back and forth via a Socket I/O connection. Four locations were monitored for the induced vertical seismic signals, including velocity, acceleration, and stress histories. The signals were analyzed by Hilbert-Huang transform to obtain the time-frequency spectrograms for examining the characteristics of the signals. The particle size, wall friction, particle friction, and parallel bond of PFC input parameters were parametrically investigated. The Xiaolin landslide in 2009 was successfully simulated, and the characteristics of the seismic signals were studied and compared with the data from a broadband seismic station. These results demonstrate that terrain and transition in the movement type of a complex landslide do influence the seismic signals. A landslide with larger rock particles generates lower-frequency content seismic signals. Also, there can be approximately 40 s to escape before a large-scale landslide hits if seismic instrumentation is installed. The method proposed can be further applied for studies on many other large-scale rock avalanches to verify recorded signals and further correlate the signals with the landslide characteristics.     

Characteristics and formation mechanism of the July 25, 2013, Tianshui group-occurring geohazards

A field investigation was conducted for the group-occurring mountain torrent geohazards that took place on July 25, 2013, in Tianshui City, China. The formation causes, range, development characteristics, and distribution laws of these geohazards were systematically revealed. In addition, a three-dimensional dynamic numerical continuum model was established to simulate the motion characteristics of the typical landslides in Tianshui City. The field investigation and simulation results show that the mountain torrent geohazards that occurred on July 25, 2013, had five major characteristics: universality and evident group occurrence, local outbreak, strong concealment, considerable potential damage, and a significant hazard chain mode. The hazards’ intensity was aggravated by the superposition effects of intense rainfall and earthquakes. Most of the landslide-prone slopes in these geohazards had a concave geometry. The landslides occurred mainly within a slope gradient range of 35°–45°; the most common slope angle was 40°. The loess landslides had a narrow-strip shape and ranged in width from several meters to 10 m and in length from 10 s of meters to 100 s of meters. These landslides were relatively small scale, with volumes from 10 to 100 s of cubic meters. The mean velocity, frontal velocity, total kinetic energy, and total potential energy of the typical landslide masses all increased sharply during the downslope motion and decreased gradually in the deposition zone. Entrainment was a very important factor in these landslide events, as it caused the mass of the hazard bodies to increase; the increased mass, together with a high motion velocity (30 m/s), enhanced the destructiveness of the hazard bodies.     

地形因子对偏转型滑坡-碎屑流运动参数的影响

根据滑坡地形特征,将沟谷偏转型滑坡划分为坡脚偏转型、凹面偏转型和凸面偏转型三种类型,其主要地形参数为滑源区坡度、斜坡坡度、沟谷坡度和偏转角度。通过数值模拟,采用正交分析、极差分析和方差分析初步探讨主要地形参数对沟谷偏转型滑坡运动参数的影响。结果表明:沟谷偏转型滑坡的视摩擦系数、前缘速度恢复系数均主要受地形起伏的影响。斜坡坡度对视摩擦系数的影响最大,沟谷坡度次之,偏转角度最小;斜坡坡度、沟谷坡度对前缘速度恢复系数的影响大于偏转角度的影响。斜坡坡度是视摩擦系数的显著性因素,斜坡坡度、沟谷坡度是前缘速度恢复系数的显著性因素。视摩擦系数、前缘速度恢复系数与主控地形因子之间存在显著的非线性关系,可分别用二次函数、二次型函数进行描述。     

Lessons Learned from the Landslides in Shengli East Open-Pit Mine and North Open-Pit Mine in Xilinhot City,Inner Mongolia Province,China

The locations of the 2013 eastern ShengLi open pit mine landslide and the 2010 northern ShengLi open pit mine landslide were both in the XilinHot city of Inner Mongolia province, in areas with similar geographical, regional geological, geomorphic conditions and excavation depth. There are so many similar characteristics, such as landslides triggered by the rain storms, landslides occurred many times, landslides with long time deformation, but there are also some differences between the two landslides, such as the scale and failure mode. Field investigations showed that the two landslides were both occurred several days after the rain storms, the eastern ShengLi open pit mine landslide body with the volume of 85 million m³ has been in persistent deformation with an observed maximum horizontal displacement of 58 m in August 2013, Furthermore the implemented check dams at east open pit mine had not formed an efficacious blocking system to resist the flow because of incorrect judgment regarding the landslide style. The northern ShengLi open pit mine landslide body with 0.5–1 million m³ occurred several times after each rain storm. In the whole, the time of persistent deformation about the eastern ShengLi open pit mine was much longer than that of the northern ShengLi open pit mine because of the difference of the filling material of fault and space combination between the faults and the slope. Field investigation, physical model experiments, real-time displacement monitoring and numerical simulation were implemented to investigate the characteristics, mechanism, and retaining measures of the two landslides. The insights gleaned herein may be valuable for the understanding of the mechanisms of landslides and improving preventative measures against these types of events in north China in the future.     

四川省汉源县中海村滑坡动力学特征数值分析

通过对中海村滑坡灾害现场的调查研究,阐明了滑坡的致灾因素和失稳机制,基于连续介质力学理论数值模型对滑坡进行了动力参数反演分析。研究结果表明: 连续降雨和第四系昔格达半成岩的特殊岩性特征是中海村滑坡发生的关键因素,滑坡运动持续时间约70 s,滑坡孔隙水压力系数为0.8,最大堆积厚度为8 m,最大运动速度为16.2 m/s; 在整个滑坡运动形态和速度演化过程中,主要堆积区域为1级平台和3级平台,运动速度出现3峰特征,阶梯型地形是出现阶段性速度峰值的主要原因。     

Formation process of two massive dams following rainfall-induced deep-seated rapid landslide failures in the Kii Peninsula of Japan

Extreme heavy rainfall due to Typhoon Talas on September 2–4, 2011 in the Kii Peninsula, Japan, triggered numerous floods and landslides. This study investigates the mechanism and the entire process of rainfall-induced deep-seated landslides forming two massive dams in the Kuridaira and Akatani valleys, respectively. The mechanism of the rapid deep-seated landslides is examined through a series of laboratory experiments on samples from sliding surfaces by using undrained high-stress dynamic-loading ring-shear apparatus. The test results indicate that the failure of samples is triggered by excess pore water pressure generation under a shear displacement from 2 to 7 mm with a pore pressure ratio ranging from 0.33 to 0.37. The rapid movement of landslides is mainly attributed to high mobility due to the liquefaction behavior of both sandstone-rich and shale samples. Geomorphic settings and landslide mobility are major contributing factors to the dam formation. Additionally, shear displacement control tests show that a certain amount of shear displacement between 2 and 7 mm along the sliding surfaces of the gravitationally deformed slopes might have led to the failures. Importantly, computer simulation with LS-RAPID software using input parameters obtained from physical experiments is employed to interpret the entire formation process of the abovementioned two landslide dams. The simulation results are examined in accordance with the observed on-site geomorphic features and recorded data to explain the possibility of sliding processes. The results further point out that local failures are initiated from the lower middle part of the landslide bodies where the geological boundary exists. This condition most probably influences the landslide initiation in the two case studies. This research is therefore helpful for hazard assessment of slopes that are susceptible to deep-seated landslides and other sequential processes in areas with geology and geomorphology similar to that of the Kii Peninsula.     

Analysis of an anti-dip landslide triggered by the 2008 Wenchuan earthquake in China

The Guantan landslide, with a total displaced mass of about 468 × 10⁴ m³, was triggered by the 2008 Wenchuan earthquake and succeeding rainfall in Jushui Town, Sichuan Province, China. The landslide occurred on an anti-dip hard rock slope with a weak rock founding stratum of 200 m in thickness. To investigate the failure mechanism of the Guantan landslide, dynamic behaviors of hard and soft rock slopes were investigated by means of large scale shaking table tests. The laboratory models attempted to simulate the field geological conditions of the Guantan landslide. Sinusoidal waves and actual seismic waves measured from the Wenchuan Earthquake were applied on the slope models under 37 loading configurations. The experimental results indicated that deformation mainly developed at a shallow depth in the upper part of the hard rock slope and in the upper (near the crest) and lower (near the toe) parts of the soft rock slope. An equation for predicting the depth of sliding plane was proposed based on the location of the maximum horizontal acceleration. Finally, it was concluded that the failure process of the Guantan landslide occurred in three stages: (1) toppling failure caused by compression of the underlying soft rock strata, (2) formation of crushed hard rock and sliding surface in soft rock as the result of seismic shocks, particularly in the horizontal direction, and (3) aftershock rainfall accelerates the process of mass movement along the sliding plane.     

Numerical simulations of the 1963 Vajont landslide, Italy: application of 1D Lagrangian modelling

On 9 October 1963, a rock mass of about 250 millions m³, with a front width of 1,850 m, a mean thickness of about 200 m and a length of 350–400 m, detached from Mt Toc, on the left side of the Vajont valley, NE Italy, and collapsed into the reservoir created by a 261 m high dam. About 40 millions m³ of water was displaced, climbed up 200 m on the opposite side and then destroyed the little town of Longarone causing more than 2,000 casualties. This event is well known and was the object of numerous technical and scientific studies, especially in the two decades following the disaster. This work proposes a re-examination of the matter, focusing on the numerical modelling of the landslide, and is carried out by using a 1D numerical code based on a Lagrangian approach. The model is properly conceived for cases with slide length prevailing on width. When the slide width is comparable or prevailing on length, as is the case of the Vajont slide, the mass is first partitioned into a number of longitudinal long and narrow sub-slides. The Vajont mass was subdivided into six strips and the motion of each sub-slide was computed. The knowledge of the final deposit position allowed us to constrain the value of some relevant parameters characterizing the slide motion, the most interesting being the friction coefficient μ, that we varied in order to obtain the best-fit between calculated and observed deposits. Taking into account the additional constraint that all sub-slides move with the same or at least with similar speed, and introducing a global misfit based on deposit and velocity misfits, we were able to show that solutions minimizing the global misfit exhibit a relevant difference between the basal friction coefficients of the western and of the eastern sides of the sliding surface, with the former being significantly smaller (0.14–0.16) than the latter (0.32–0.34).     

地震与非地震诱发滑坡的运动特征对比研究

针对不同诱发机制的滑坡运动特征差异,以滑坡的总斜率和阻止系数为评价指标,分析滑坡的总斜率、阻止系数与滑坡规模、总能量的关系,对比研究了地震和非地震滑坡的总斜率、地形阻止系数的特征。研究结果表明：地震与非地震滑坡的规模越大在运动过程中受到的阻止作用越小;地震滑坡和非地震滑坡的总斜率都随滑坡规模和总能量增加而减小,但地震滑坡减小的速率大于非地震滑坡;地震滑坡的平均阻止系数约为0.4～0.5,而非地震滑坡的平均阻止系数约为同规模地震滑坡的40%～50%。因此,滑坡的运动特征不仅受滑坡规模及总能量控制,还显著地受滑坡的诱发机制和地形阻止等因素的影响。