地震诱发边坡浅层岩体破坏深度及破坏机制研究

There are 49 large hydropower stations lacated in high earthquake-intensity area in west China, engineering slope failure is significant potential safty hazard.Research on failure process of engineering slope triggered by earthquake and qualitative research on seismic wave propagation rule are mainly focused on, and that the dynamic failure mechanism and the damage depth of slope subjected to earthquake are still not clear,so the aseismic design is still based on the pseudo-static analysis, and the defined depth of rockmass to be protected is also not the damaged area in dynamic condition, so the aseismic design is lack of pertinence and and effectiveness. This project will suty the earthquake wave propagation rule while it encounters the rockmass structural surface and reaches to the slope surface. Based on the distribution and variation of stress, strain and strain energy density of rock mass caused by seismic motion, the failure depth of slope triggered by earthquake and the propagation rule of seismic wave will be quantitatively studied, and so the protection depth of engineering slope subjected to earthquake will be defined. The indoor tests on dynamic properties of rockmass will be conducted, numerical analysis will be employed to simulate the dynamic slope failure process and calculate the quantitative relationship between the seismic wave propagation rule and the failure scope of slope, and the physical modelling experiment will be carried out to verify the numerical simulation results.And finally, the surperficial rockmass failure mechanism of slope subjected to earthquake will be worked out and the damaged depth of slope rockmass caused by seismic wave propagation can be quantified, based on which the protection depth of superficial slope rockmass under earthquake can be defined and so the protection zone of slope can be defined based on this. This research will provide basis for aseismic design of engineering slope under earthuqake.

我国西部有49座大型水电站处在高地震烈度区，地震诱发工程边坡破坏是重大的安全隐患。目前对工程边坡动力问题的研究多以边坡破坏过程和地震波在边坡内传播规律的定性评价为主，而由于对边坡动力破坏模式、范围等的预测不准确，抗震设计也多以传统的拟静力法为依据，防护范围也非动力条件下引起的破坏范围，因此缺乏针对性和有效性。本项目拟针对地震波遇到边坡岩体结构面及临空面的传播规律，从地震波动引起边坡岩体应力、应变以及应变能密度变化的角度出发，以地震波放大传播规律及其对边坡破坏的影响深度的定量分析、地震条件下工程边坡防护厚度的确定为主要研究内容，结合室内岩体动力特性试验、数值模拟计算及物理模型试验对比验证，重点解决地震条件下如何定量描述地震波动对边坡破坏的影响深度及工程边坡浅层岩体破坏机制的关键科学问题，最终达到定量化地震波放大传播规律以及工程边坡地震防护厚度，为建立相应的工程边坡地震防控原则提供依据。

本项目以地震作用下边坡浅层岩体破坏的“山扒皮”现象为研究对象，从地震波在岩石介质中的传播规律出发，以地震波在边坡中的放大传播规律及其对边坡浅层岩体破坏的影响深度为主要研究内容，探讨了地震作用下工程边坡浅层岩体破坏机制和破坏深度，同时对地震条件下边坡防护厚度的确定方法进行了讨论。得出的主要成果如下：.⑴地震波在实际边坡中的传播具有明显的坡高特性。.水平加速度及竖直加速度随高程的放大效应具有显著不同，在坡体中下部竖直加速度放大系数基本高于水平加速度放大系数，而当达到一定高度后，水平加速度放大系数急剧增大，显著高于竖直加速度放大系数。经过统计分析认为对于岩性相同的边坡无论坡体结构如何，满足一定的关系.⑵试验结果表明边坡动力响应特性与其破坏现象具有明显的对应性。.地震加速度、位移在边坡坡面急剧放大的趋表及趋高特性是引起坡面岩体破坏异常严重的一个重要因素。但这种强烈破坏区仅仅局限于一定范围内。边坡产生强烈动力响应的边坡高度约为坡高的1/4处。.分析了动力输入基本参数对边坡动力响应的影响。对于一个动力输入其基本参数有三个，即：振幅、频率和持时。结论认为：响应加速度随动力输入幅值的增加而呈非线性增大的趋势，在大约3/4坡高以上这种趋势“愈演愈烈”；动力输入频率的增加同样会使得坡体内加速度随之非线性增加，但频率越高加速度在坡体内分布的节律性越明显，且加速度出现急剧增加的坡高越低；动力输入的持时对边坡动力响应影响较小，但持时的增加会加剧地震波作用在坡体上的累积效应。.⑶结合现场调查及模型试验结果，分析了岩质边坡浅层岩体破坏的动力机制。提出了一种地震条件下岩层倾倒型破坏解析解分析方法。.⑷结合数值计算及模型试验结果探讨工程边坡地震防控方法。.结合地震波在坡体内传播规律的分析及地震波传播对边坡浅层岩体破坏的影响范围，对工程边坡地震防护方法进行了初步探讨。