水力条件下具有张裂缝临河边坡稳定性分析

STUDY OF STABILITY OF SLOPE WITH TENSION CRACK NEAR RIVER UNDER HYDRAULIC SITUATION

临河边坡由于多种因素可引起坡顶面出现张裂缝,而在水力条件下坡体则变得越不稳定,以致可能发生失稳,因此对水力条件下张裂缝临河边坡的稳定性分析具有重要意义。基于直线滑动面方法、圆弧滑动面方法和滑动面搜索新方法,对此类边坡进行稳定性分析。在考虑渗流作用的情况下,将流网进行合理简化,且以土体、土骨架为研究对象及采用等效容重法对滑动体进行受力分析。直线滑动面时,推导出折线型和台阶型边坡的安全系数计算公式。通过算例分析,并分别研究坡外水位和张裂缝积水深度变化对边坡稳定性的影响,可得到如下结论:(1)对于最小安全系数的计算,直线滑动面方法偏大,滑动面搜索新方法与圆弧滑动面方法相接近,但比圆弧滑动面方法小;(2)采用相同类型滑动面搜索方法时,以土体与土骨架为研究对象分析得出的结果一致,以土骨架为研究对象和等效容重法分析得出的结果等效;(3)坡外水位在一定高度及以下时,不同类型滑动面方法均表明边坡将处于不稳定状态;(4)随张裂缝积水深度的升高,采用不同类型滑动面搜索方法计算得到的安全系数都将减小,说明张裂缝积水深度越高,边坡状态越不稳定。

Due to affect of many factors,cracks might appear on the top surface of slope along river.The slope would become more and more unstable under hydraulic situation so as to lead to slope instability.Therefore,it is of great significance to study the stability of slope with crack near river under hydraulic situation.Based on methods of linear sliding surface,circular sliding surface and a new method of searching for sliding surface,the stabilities of slopes with crack near river are analyzed.In consideration of seepage,flow nets are reasonably simplified;and soil mass and soil skeleton are taken as research object respectively or method of equivalent bulk density are used to analyze the force of sliding mass.When sliding surface is linear,formulae for calculating safety factor are derived in slopes with shapes of broken lines and steps.The influences of water levels outside slope or in crack on stability of slope are studied respectively by case study.Some conclusions are drawn as follows：（1） According to the calculation results,the minimum safety factors got by method of linear sliding surface are the largest;and values got by a new method of searching for sliding surface are close to,but smaller than those got by method of circular sliding surface.（2） When the type of method of searching for sliding surface is same,the research results obtained by taking soil mass and soil skeleton as research object are consistent.The research results obtained by taking soil skeleton as research object and using method of equivalent bulk density are equivalent.（3） When the water level outside slope is at or below a certain height,all different types of methods of searching for sliding surface show that slope would be unstable.（4） The minimum safety factors got by different types of methods of searching for sliding surface gradually decrease with increasing water level in crack,which indicate that the higher the water level in crack is,more unstable the slope is.