几何参数对边坡稳定可靠度影响规律分析

Influence of slope geometry on slope reliability evaluation

坡高和坡率是影响边坡稳定可靠度的重要因素。利用积分中值定理推导基于Fellenius法的黏性土简单边坡稳定可靠指标的解析表达式,讨论边坡安全系数和可靠指标随几何和材料参数变化的非协同响应特性;基于Monte-Carlo方法,分析坡高和坡率引起边坡安全系数和可靠指标非协同响应的土体强度条件。研究结果表明:特定几何和材料参数下的边坡安全系数和可靠指标将呈现出相反的演化趋势,与边坡安全系数随土体强度和几何参数的不利变化而降低规律不同,在黏聚力小且变异性大、内摩擦角大且变异性小条件下,边坡可靠指标出现随坡高增加而提高的特殊变化现象;对于黏性土边坡,采取放缓边坡的工程措施,较降低坡高,既能提高边坡安全系数,也能保障边坡的可靠指标提高,降低工程安全风险。

Slope height and slope gradient have a significant influence on slope stability.Based on the Fellenius method,the reliability index formulas of cohesive-frictional soil slope were derived using the integral mean value theorem in the paper.The influence of slope height and slope gradient on nonuniform response between the factor of safety and reliability index was analyzed.Monte-Carlo method was used to investigate the conditions of soil properties which leads to inconsistent changes between safety factor and reliability index.Results show that,in some specific conditions,opposite tendencies for the factor of safety and reliability index may be encountered.For cohesive-frictional slopes,when the mean of the internal friction angle and the standard deviation of cohesion are large,and the mean of the cohesion and the standard deviation of internal friction angle are small.The reliability index increases as the slope height decreases.This means that,compared with the approach of reducing slope height,the method of decreasing slope gradient can ensure the increase of both factor of safety and reliability index more efficiently.