基于有限圆弧和强度折减方法的渠道开挖临界坡度研究

 基于有限差分法，得到单元应力、应变和位移计算结果，建立以极限平衡理论为基础的有限圆弧法和以变形变化趋势为破坏标准的强度折减法，搜索出边坡临界滑动面和最小安全系数，通过算例验证及参数对计算结果的影响分析，证明所建方法应用于边坡工程的可行性。文中方法结合极限平衡方法共同应用于南水北调工程大型渠道土质边坡开挖临界坡度研究中，选取高边坡、填筑边坡、深挖方边坡3种典型的渠道边坡模式，得到安全系数随开挖坡度的变化曲线，对比分析确定出渠道边坡的临界开挖坡度。研究表明，渠道高边坡和填筑边坡对开挖坡度要求较高，相对挖方卸载，填筑加载对边坡的稳定性影响较大，文中方法具有较高准确性和合理性，弥补现存方法的不足，不但可解决大型渠道边坡设计问题，也可为类似边坡工程提供参考。

STUDY OF CRITICAL SLOPE DEGREE OF CHANNEL EXCAVATION BASED ON FINITE ARC AND STRENGTH REDUCTION METHOD

Stress，strain and displacement in slope are calculated using the finite difference method. The finite arc method is presented based on the limit equilibrium theory and strength reduction method with deformation?s change trend as a standard of failure. The presented method is applied to search critical slip surface and the minimum safety coefficient of slip，and the case studies with verification and parameters? discussion demonstrates the accuracy in the application of slope engineering. The presented method and the limit equilibrium method are applied to study critical slope of one large channel excavation in South-to-North Water Diversion Project. In the study three typical channel?s slope modes including high slope，reclaimed slope and deep excavation slope mode are selected to get the safety coefficients? change with slope degrees of excavation，then the critical excavated slope of channel can be determined. The computed results show that high slope and reclaimed slope in the large channel require a high level for excavated slope degree. Compared to the excavation，the filling load owes more effect on the slope?s stability. It?s found that the presented methods in this paper more accurate and rational，which could complement the insufficiency of existing methods. The methods not only solve the design problems of large channel?s slope，but also provide a good reference for the similar slope engineering.