倾向下游与河谷的多层软弱结构面坝肩边坡抗滑稳定研究

Study on anti-sliding stability of dam abutment slope with muti-layer weak structure inclined to downstream and river valley

某工程为50 m高对数螺旋线型双曲拱坝,施工阶段发现其左拱端坝肩边坡存在多条缓倾向临空面的软弱层,对工程安全稳定有重要影响。提出增大拱端嵌深、浇筑垫座的方案,并基于Drucker-Prager(D-P)本构关系,采用强度折减法对加固后左拱端坝肩边坡进行弹塑性有限元计算,分析边坡塑性区发展过程及多软弱层影响下边坡的破坏模式。研究结果表明:多层软弱层对拱端边坡稳定及破坏模式有显著影响;在降强过程中,塑性区由各软弱层底部开始沿软弱层独立发展并彼此贯通,破坏后期塑性区与临空面贯通,形成破坏通道;根据塑性区的发展过程,在多层软弱层影响下,边坡表现为软弱层破坏并相互贯通-坡脚滑移-坡顶拉裂的破坏模式。

A 50-meter high hyperbolic arch dam of logarithmic spiral type was constructed. During the construction stage, it was found that there were several weak layers with a gentle dip in the slope of the left bank abutment, which had an important influence on the safety and stability of the project. This paper puts forward the scheme of increasing the arch abutment embedded depth and pouring cushion. Based on Drucker-Prager(DP)constitutive relation, the elastic-plastic finite element calculation of the slope of the left arch abutment after reinforcement is carried out by strength reduction method, the development process of the slope plastic zone and the failure mode of the slope with multiple weak layers is analyzed. The results show that the multi-layer weak layer has significant influence on the stability and failure mode of abutment slope. In the process of strength reduction, the plastic zone develops independently along the weak layer from the bottom of the weak layer, and then connects with each other. In the late stage of failure, the plastic zone connects with the surface and forms a failure channel. According to the development process of the plastic zone, the slope under the influence of the multi-layer weak layer presents the failure mode of the weak layer breaking and connecting with each other,slope toe slipping and slope top cracking.