岩石高边坡开挖卸荷松弛准则研究与工程应用

Research on unloading relaxation criterion of high rocky slope excavation and its engineering application

基于对卸荷松弛过程和机制的定性分析,提出了以岩石极限拉应变作为卸荷松弛的判别准则。通过对岩石极限拉应变室内试验资料与其抗拉强度之间关系的分析,并结合小湾工程卸荷松弛分析的成功实践经验,提出了极限拉应变值的取值原则,并明确了岩石边坡开挖后实际拉应变的计算方法。运用三维弹黏塑性加锚节理岩体流变模型,将该准则和计算方法应用于锦屏一级拱坝建基面开挖卸荷松弛的数值分析中,通过与实际开挖揭示和声波测试资料的对比,结果表明分析结果较为合理,为工程建设提供了有益的指导。

The research advance and existent insufficiency of unloading relaxation in rocky slope excavation are summarized.Based on the qualitative analysis of unloading relaxation process and mechanism,the limit tensile strain of rock is proposed as the criterion of unloading relaxation.The value taking principle of limit tensile strain of rock is put forward by analyzing the relationship between lab test value of limit tensile strain of rock and its tensile strength,and by referring to the successful practice of excavation unloading relaxation analysis in Xiaowan arch dam.The calculation method of tensile strain in rocky slope after excavation is deduced.By adopting three-dimensional elasto-viscoplastic finite element method of reinforced jointed rock masses,this unloading relaxation criterion and corresponding calculation methods are applied to the numerical analysis of rocky slope excavation unloading relaxation in Jinping First-Cascade arch dam foundation plane.By comparing to the disclosed situation after actual excavation and the sonic wave testing data,the results of numerical analysis are confirmed reasonable,so as to provide beneficial guidance to the construction of project.