考虑突变理论的顺层岩质边坡失稳研究

Analysis of mechanism of bedding rock slope instability with catastrophe theory

应用突变理论,以顺层岩质边坡为例,考虑地下水对滑面带介质的应变和水致弱化性质,以及地下水对边坡后缘张裂缝的水力效应,构建了边坡的尖点突变模型,分析了顺层岩质边坡失稳的力学机制:边坡失稳过程主要是内部因素和外部因素共同作用的结果,内部因素主要是地下水通过物理化学作用软化了滑面带岩体,使滑面带岩体刚度比降低,在边坡失稳的过程中起主导的定性作用;外部因素主要是指边坡后缘张裂隙的静水压力,不仅使得边坡的滑动势能增加,还对边坡造成一种扰动的作用,加速滑坡的启动。在突变分析的基础上,推导了边坡后缘张裂缝临界充水高度和临界降水强度的关系式,建立了边坡滑移破坏的水力判据;给出了边坡岩体在渐进软化过程中的位移变化规律,剪切位移并非均匀增长,而是呈现出阶梯状跳跃式上升。同时,进行了室内物理模型试验(当刚度比λ→0),在一定程度上验证了考虑突变理论来分析顺层岩质边坡失稳的力学机制和边坡岩体在渐进软化过程中位移变化规律的合理性。并提出了此种类型边坡的处治技术与优化方法建议。

On the basis of catastrophic theory, taking bedding rock slope for example, a new catastrophic model on slope stability is established in consideration of elasto-brittle medium and strain-softening medium of the slip surface and the hydrostatic pressure of top splay fracture, then the mechanism of bedding rock slope stability is discussed. It is shown that： the stability of bedding rock slope is mainly affected by two factors, namely internal and external factors. The internal factors indicate that groundwater softens the rock mass of slip surface by physicochemical effect, so the rigidity ratio of rock mass is reduced, which plays a leading qualitative effect. The external factors refers to hydraulic pressure. It not only makes the sliding potential of the slope increasing, but also plays a role as a disturbance in the process of slope instability to speed up the landslide. On the basis of these, equations calculating the critical water height in the splay fracture and the critical rainfall intensity are derived, and then the bedding-slip failure hydraulic criterions for bedding rock slope are proposed. The displacement change rule of the rock mass of slip surface in the progressive softening is also given. The increasing of shear displacement is not uniform; it presents a leap which likes a ladder. Simultaneously, the physical model test is carried out （rigidity ratio λ→0 ）, which validates the rationality of instability mechanism and the displacement change rule of bedding rock slope with catastrophe theory. Furthermore, some suggestions of treatment technology and optimization methods for this kind of rock slope are proposed.