考虑坝基岩体抗剪强度各向异性的重力坝抗滑稳定分析方法

Analysis on anti-sliding stability of gravity dam under consideration of anisotropic shear strength of dam foundation rock mass

为研究节理岩体抗剪强度各向异性特征对重力坝抗滑稳定性的影响,利用结构面网络模拟技术,计算节理岩体在主滑动方向上沿不同角度剪切的连通率与相应的抗剪强度参数,对Mohr-Coulomb强度准则进行各向异性修正。在此基础上,结合极限分析法,提出了一种考虑岩体抗剪强度各向异性特征的重力坝抗滑稳定分析方法。将该方法应用于向家坝泄12坝段的深层抗滑稳定分析,并与传统方法的计算结果进行对比。结果表明:该方法与传统方法获得的临界滑裂面位置比较接近,但其抗滑稳定安全系数明显小于传统方法,且临界滑裂面的剪出段倾角与坝基岩体连通率的最大值方向基本一致,和实际情况相符。该方法充分考虑了岩体抗剪强度各向异性的影响,对合理评价重力坝的抗滑稳定性具有重要的工程和现实意义。

In order to study the influences from anisotropic characteristics of the shear strength of the jointed rock mass on the anti-sliding stability of gravity dam, both the joint connectivity rates of the jointed rock along the shear surfaces with different inclination angles in the main sliding direction and the corresponding shear strength parameters are calculated with the technique of the network simulation of structural plane, and then the anisotropic modification is made on Mohr-Coulomb strength criterion. On the basis of this, a method for the analysis on the anti-sliding stability of gravity dam under the consideration of anisotropic shear strength of dam foundation rock mass is proposed herein in combination with the limit analysis method. This method is applied to the deep anti-sliding stability analysis on the No.12 flood-discharge section of Xiangjiaba Gravity Dam, from which the result is compared with that from the calculation made by the conventional method. The result shows that the position of the critical slip surface obtained from this method is more close to that obtained from the conventional one, but its anti-sliding safety factor is obviously less than that from the conventional method. Furthermore, the shearing section inclination angle of the critical slip surface obtained from this method is basically coincided with the direction of the maximum value of the connectivity rate of the dam foundation rock mass, which is consistent with that of the actual situation. This method fully considers the influence of the anisotropic shear strength of rock mass has important engineering and practical significance for reasonably evaluating the anti-sliding stability of gravity dam.