IBE-PFE方法在某水电站泄洪洞出口边坡稳定分析中的应用

Application of IBE-PFE method to analysis on stability of slope around flood discharge tunnel outlet of a hydropower station

鉴于传统方法在含复杂结构面岩质边坡稳定分析中的局限性,引进分区有限元与块体界面元混合算法,验算边坡的稳定性。针对某水电站泄洪洞出口边坡地形地质条件和结构面分布特点,建立数值模型。采用分区有限元与块体界面元混合算法,并结合强度折减法,逐步降低不连续面抗剪强度,计算得出块体刚体位移和接触点对接触状态。根据块体刚体位移发生突变并结合滑动通道失效点对完全连通,确定了边坡的安全系数和破坏方式。结果表明:边坡稳定安全系数为1.80;边坡最可能以坡顶预设缝、坡脚预设缝以及f_(555)结构面为滑动通道发生失稳破坏。该方法具有准确确定边坡危险滑动面和安全系数的优点。

Considering the limitations of traditional methods in the stability analysis of rock slope with complicated structural planes,an algorithm mixed with the partitioned finite elements and the block-interface boundary elements is introduced to calculate the stability of slope. According to the topographic and geological conditions and structures layout of the slope around the flood discharge tunnel outlet of a hydropower station,a numerical model is established. The displacement of the block rigid body and the contacting state of the contact pairs are obtained from the calculation through continuously reducing the shear strength of the discontinuous surface with the mixed algorithm combined with strength reduction method. The safety factor and the failure mode are determined in accordance with the occurrence of a sudden change of the displacement of the block rigid body combined with the full connection of the failure point pairs of sliding passage. The safety factor of the slope stability is finally determined to be 1. 80. The instability failure most possibly occurs along the sliding passage formed by the pre-arranged joint at the slope top,the pre-arranged joint at the slope toe and the f_（555） structural plane. The result shows that the method has the merit of correctly determining the dangerous sliding surface and the safety factor.