江坪河水电站溢洪洞围岩稳定性仿真分析

以江坪河水电站溢洪洞进口段为工程背景，基于大型有限元分析软件ANSYS，模拟地质地形，包括不同岩层、断层条件，采用弹塑性有限元模型和Drucker-Prager屈服准则，对溢洪洞施工全过程进行非线性数值仿真计算分析，得到了不同岩层围岩的应力和位移分布规律。通过对位移、应力场，特别是拉应力大小、深度的分析，以及塑性区和点安全系数分布等的综合分析，对溢洪洞进口段在开挖未支护和开挖后及时支护两种工况下的稳定性进行了评价。计算结果表明，隧洞进口段围岩开挖未支护时，洞顶下沉位移大，有大面积塑性区和超过岩体抗拉深度的区域，稳定性差。及时支护后，洞顶塑性区和超过岩体抗拉深度的区域减小，稳定性明显提高，但CK2强风化层支护区的点安全系数略大于1.0，且内部仍有小于1.0的区域。因此，建议CK2强风化层加强支护，最好采取钢拱架强支护措施，其结果为设计和施工提供了重要参考。

Simulation analysis of stability of spillway tunnels of Jiangping River Hydropower Station

Taking the spillway tunnels for Jiangping River Hydropower Station as engineering background, their stabilities in the construction period are analyzed by using large-scale finite element analysis software ANSYS and according to actual geological and topographical characteristics, including different rock strata and faults conditions, Drucker-Prager criteria, nonlinear numerical simulation calculation. The principal stress and displacement distribution law of different rock strata are obtained. Through the analyses of displacements and stress field, expecially the synthetic analysis of tension stress zone, plastic area and point safety factor distribution, the stabilities of spillway tunnels entrance before and after supporting are evaluated. The displacement in the top of tunnel is large; moreover, there are big plastic area and zone that exceed tensile strength of rock body; the stability is poor. After supporting timely, plastic area and zone that exceed tensile strength of rock body become smaller; its stability is improved obviously; but the point safety factor of strongly weathered layer CK2 is just slightly larger than 1.0; and there is still zone inside of which the point safety factor is less than 1.0. Therefore, for the strongly weathered layer CK2, it is best to take measures of strong supporting with steel arch frame. The results provide an important reference for engineering design and construction.