震裂斜坡形成机理及变形破坏模式研究

震裂斜坡是强震作用下形成的一类分布范围广、震裂变形严重、潜在危害大的次生地质灾害,为了深入系统地分析其震裂机理及变形破坏机制模式,本文结合"5.12"汶川大地震造成的震裂斜坡及其破坏现象的详细调查,在对强震中的地震波效应深入分析的基础上,以双面斜坡为例,首先对震裂变形的力学机理进行了系统分析。认为强震中的体波效应将导致斜坡体处于量值和方向不断变化的拉-剪应力和反压应力的交替作用之下,其形成的拉-剪破裂效应和潜在的楔劈效应是斜坡震裂变形的重要力学因素之一。同时,面波效应将导致坡体表面处于鼓胀拉力和扭力的作用之下,是坡体表部整体震裂破碎甚至破坏的另一重要力学因素。二者共同作用均使坡体应力场处于不断的动态变化过程中,坡体(面)震裂变形甚至破坏更为严重。在此基础上,对强震中斜坡变形破坏的机制模式进行了归纳,认为主要有四种表现形式,即旋转-拉裂型、旋转-剪滑型、鼓胀-拉裂型和滑移-拉裂型。研究成果为震裂斜坡稳定性分析以及灾后重建和防灾减灾提供了有力参考。

Study on formation mechanism and deformation failure models of shatter slopes

The shatter slope is a type of secondary geological hazards under the action of strong earthquake. Its distribution is wide, its shatter deformation is serious, and its potential hazard is great. In order to thorough and systematically analyze the shatter mechanism and the deformation failure mechanism models, this paper, combined with the detail investigation to the shatter deformation and destroy phenomenon caused by "5. 12" Wenchuan big earthquake, and under the condition of fully analyzed the earthquake wave effects, preliminary and systematically analyzed the mechanism of double-side slope shatter deformation. It considers that the action of body waves make slope under the alternative action of pulling-shearing strength and counter pressure strength, which quantity value and orientation change continuously. This will form pulling-shearing rending effect and potential wedge split rending effect, which is one important factors of shatter formation. At the same time, the surface wave will make the slope surfaces suffer the action of ballooning pulling force and torsion. This is still the significant reason of shatter deformation. All these will lead to the stress field of slope body under the process of continuous dynamic variation, and will make the shatter deformation become more serious. On the basis of above, the paper still analyzed and concluded the deformation failure mechanism models of slopes in the process of strong earthquake. It thinks that the deformation failure mechanism models have four typical representation forms, which are rotating and fracturing model, rotating and shearing-sliding model, ballooning and fracturing model, and sliding and fracturing model. The study results will provide vigorous reference for analysis of shatter slopes stability and reconstruction after earthquake and hazard resistant and reduction.