【作者】 李稳哲；

【导师】 赵法锁；

【作者基本信息】 长安大学 ， 地质工程， 2013， 博士

【摘要】 灾难性高速远程滑坡能将不安全区扩展到远在滑坡形成区之外，这种扩展是由其高速运动特征（冲击气浪、涌浪及溃坝洪水）间接实现，或者通过远程运行直接实现的。本文全面阐释了唐家山滑坡的地质背景和滑坡工程地质特征，重点分析了唐家山原始斜坡在地震作用下的动力失稳机制。同时，首次系统分析了在地震作用下滑坡体边坡稳定性，高速滑坡的动力过程，高速滑坡超前气浪灾害及高速滑坡涌浪特征等。主要结论如下：1）全面阐释震前唐家山所在边坡地形地貌、地层岩性、地质构造、岸坡结构特点，唐家山滑坡的形成条件：①高陡边坡，潜在势能大；②靠近发震断裂部位；③原始斜坡岩层软硬相间，为典型的中陡倾顺向坡；④汶川8级强震。2）唐家山原始斜坡在地震作用下动力失稳机制为：①坡顶对地震力的放大效应使斜坡顶部处于拉剪应力状态，当应力的组合效应超过原始弱面的强度时，岩体内的微裂隙开始扩展，并出现宏观破坏形成拉裂缝，拉裂缝与原始弱面一起构成了滑坡后壁拉裂面；②破碎岩块进入拉裂面，并产生“楔子”效应，使裂缝前端产生拉应力集中区，拉裂面扩张；③层面被地震力拉张扩容破碎的岩块和岩屑进入层面之间，碎块体的转动和岩屑的流动机制使斜坡沿岩层面剪切滑移加剧；④斜坡深部锁固段岩体（并非弱面）突发剪断，储存于锁固段的形变能瞬间释放，并大部分转化为岩层切向的动能，滑坡体骤发启动。3）唐家山滑坡为地震作用下的剧动滑坡。唐家沙滑坡模型在自然状态下计算出的安全系数为1.46，表明边坡在自然状态下是相对稳定的。而在汶川地震作用下，边坡岩体沿软弱夹层形成塑性贯通区（与真实的滑坡体一致）；滑体（塑性区）在启动时可获得很大的位移（可达2m以上），表明边坡失稳，同时滑体启动速度很大（水平速度可达4m/s，竖直速度在地震波30s时可达14m/s），由此表明此滑坡属剧动滑坡。4）为了保证滑坡体的完整性，本文首次采用有限元方法对唐家山滑坡的动态过程进行了数值模拟。滑体滑至边坡底部约用20s，与工程估算的最大滑体速度（滑体滑至底部）发生在前25s一致。滑体沿着坡面向下滑动的水平速度最大可以达到50m/s，竖直速度最大可以达到30m/s，此为高速滑坡。滑体滑动至边坡底部后，水平滑距约为900m，竖向滑距约为300m，与地震后唐家山滑坡的实测结果（水平滑距900m，竖向滑距350m）相吻合，此为远程滑坡。5）唐家山高速滑坡超前气浪在前方100m范围内产生12级以上的大风，强烈的超前冲击气浪推倒房屋，折断树木。同时对滑坡不安全区计算表明，超前气浪对千米内的人居环境都将造成破坏。6）本文首次对高速滑坡涌浪进行了理论研究，由于滑体速度大于浪的传播速度，因此，高速滑坡涌浪只能出现首浪——即滑体高速推动挤压下的水体上扬。唐家山高速滑坡涌浪最大高度理论模拟约为60m，比根据涌浪在河道对岸留下的痕迹而估测的浪高40m大50%。7）为有效地分析高速滑坡涌浪特征，建立了滑坡体体积、入水速度和水深等因素影响的高速滑坡涌浪物理模型，计算分析表明：①滑坡体体积对高速滑坡涌浪高度影响最大，而滑坡体入水速度对高速滑坡体涌浪高度影响较小。②滑体在水中运动过程中，滑体对运动前方的水挤压，造成滑体前方局部水压急剧增大，这是导致产生涌浪的根本原因。通过对剧动高速滑坡及其涌浪的研究，可以及时采取适当的工程防范和治理措施，以最大限度地减小滑坡涌浪造成的灾害，从而保障人民的生命和财产安全，且可为防灾减灾决策的制定提供科学依据。更多还原

【Abstract】 Catastrophic high-speed long-distance landslide can extend unsafe area as far as the landslide area，this extension is realized indirectly by the high speed motion features (such as shock wave, surge anddam-break flood) or realized directly by long-distance sliding. In this paper geological background andengineering geological characteristics of Tangjiashan landslide are expounded comprehensively and thedynamic instability mechanism of Tangjiashan original slope is analyzed detailedly under Wenchuanearthquake. For the first time, it is systematicly studied for the landslide slope stability under earthquake,the dynamic process of high speed landslides, air shock wave caused by high-speed landslide andhigh-speed landslide surge characteristics. The main conclusions are as follows:1) The terrain slope, lithology, geological structure and the slope structure characteristics areexpounded comprehensively for Tangjiashan before the earthquake, and it formation conditions ofTangjiashan landslide respectively are high and steep slope, near the seismogenic fault location, the typicalsteep slop and Wenchuan8seismic intensity.2) Dynamic instability mechanism of Tangjiashan original slope under seismic can be explained asfour apects:①amplification effect of seismic forces makes slope top in tensile shear stress state, when thecombined effects of stress is more than the original weak surface strength, micro fracture in the rock beginsto expand, and the emergence of macroscopic destruction forms the tension crack, then the tension crackand the original weak surface constitute the landslide cracking surface.②the broken rock entries into thecrack surface, which produces a "wedge" effect, tension stress concentration zone produces in front of thecrack and the crack surface expands.③the broken rock and debris broken by seismic tension expansionentry into the level, clastic bodies rotation and flow mechanism of debris make the rock level shear slipincrease.④locked deep rock mass of the slope (not weak surface) burst cut off, the deformation stored inlocked section can instantly released, and most of the deformation translates into tangential kinetic energyfor rock layers to slide flash boot.3) Tangjiashan landslide is series landslide under earthquake. The slope stability is simulatednumerically under the natural state (only with the gravity action), and the calculated safety factor is1.46,which indicates that the slope is relatively stable under the natural state. Secondly in Wenchuan earthquake, Tangjiashan landslide stability is numerically simulated with large amplitude seismic wave of initial30sand the free field boundary condition for the slope. The results show that the piercing plastic zone in slopeis produced in Wenchuan earthquake, and the simulation plastic zone is good agreement with the reallandslide slope body. Because of the earthquake acceleration, the slope will generate larger displacementand velocity, which produce tremendous energy in the landslide and cause serious disaster and loss.4) In order to ensure the integrity of the landslide, for the first time the dynamic process of TangJiashan landslide is simulated by finite element method. The horizontal speed of landslide along the slopesliding down can reach50m/s, vertical speed can reach30m/s, and maximum speed is at about20s afterthe earthquake. Landslide slope slides to the bottom, the horizontal sliding distance is900m, verticalsliding distance is300m, which are agreement with the measurement results (horizontal slip900m,vertical slip350m) of TangJiashan landslide after the earthquake.5) Tangjiashan high-speed landslide leads air shock wave producing more than12wind in front of the100m range, strong airblast exists to tear down the house, broken trees. At the same time landslide unsafearea calculation results show that air shock wave could cause damage in the range of kilometer for livingenvironment.6) For the first time high-speed landslide surge is studied theoretically. Because speed of the slidingbody is bigger than the wave propagation speed, only high-speed landslide surge wave appears, which isthe water rising under the pressure caused sliding body. The maximum height of theoretical simulation ofTangjiashan high-speed landslide surge is about60m, which is higher50%than the wave height40m ofthe estimation according to leave surge in river across the traces.7) In order to effectively analyze characteristics of high-speed landslide surge, high-speed landslidephysical model is established for the influence factors of landslide volume, landslide velocity and waterdepth, calculation results show that:①landslide volume is the biggest impact on high-speed landslidesurge height.②In the process of the sliding body in the water movement, water can be extruded by thehigh-speed landslide body and local water pressure increases rapidly, which is the fundamental cause of thesurge.Through this research of high-speed landslide and its surge, the timely and appropriate engineeringprevention and control measures can adopt to minimize the landslide and surge disasters, which canprovide a scientific basis for disaster prevention and mitigation decisions, so the safety of people’s livesand property can be ensured.更多还原