高拱坝谷幅变形机制及非饱和裂隙岩体有效应力原理研究

蓄水期谷幅变形影响着高拱坝当前工作性态和长期安全状况,但拱坝设计方法中尚没有相关的评价标准。首先总结蓄水期高拱坝坝址谷幅变形规律和常规数值方法计算的难点。从裂隙水压力的作用规律出发,在弹塑性模型屈服函数中引入静水压力,并应用于锦屏一级拱坝蓄水期计算分析。计算结果与监测值符合良好,初步解释谷幅收缩等坝址区山体变形现象。探索蓄水初期裂隙岩体的细观变形机制,提出非饱和、非贯通裂隙岩体中的有效应力原理。结果表明,裂隙水压力改变岩体平衡状态,是蓄水后坝址区岩体产生塑性变形的主要驱动力。

MECHANISM OF VALLEY DEFORMATION OF HIGH ARCH DAM AND EFFECTIVE STRESS PRINCIPLE FOR UNSATURATED FRACTURED ROCK MASS

Valley deformation induced by impoundment affects the current working behavior and long-term safety of high arch dams. However，the evaluation criterion for the influence of valley deformation is still limited in the design method of arch dam. In this paper，the features of valley deformation during impoundment in the site of high arch dam and the limitation of conventional calculation methods were summarized. Based on the effects of water pressure in fractures，the hydrostatic pressure was taken into consideration in the yield function of elastoplastic model，and applied in the numerical simulation of Jinping I arch dam. The calculated displacements agreed well with the observed values，which preliminarily explained the reduction of valley width and other deformation phenomena in the dam site. The mesoscopic deformation mechanism of fractured rock mass during initial impoundment was then explored. The effective stress principle for unsaturated and non-persistent fractured rock mass was presented. The research revealed that the water pressure distributed in fractures changed the equilibrium state of rock mass，which was the main driving force of plastic deformation in the dam site after impoundment.