饱水软化效应下砂质泥岩边坡三维稳定性上限分析  

Upper bound limit analysis for stability of 3D slopes of sandy mudstone considering the effect of saturation softening

作　　者：张标 瞿凡 蒋毅 Zhang Biao;Qu Fan;Jiang Yi(Hunan University of Scienceand Technology,Xiangtan 411201,China)

机构地区：[1]湖南科技大学,湖南湘潭411201

出　　处：《土木工程学报》2025年第4期108-123,共16页China Civil Engineering Journal

基　　金：国家自然科学基金(52004088)。

摘　　要：考虑到地下水的饱水软化效应和孔隙水压力效应,将不同饱水时间下岩体单轴抗压强度引入到Hoek-Brown强度准则中,并将孔隙水压力视为外力作用在三维岩质边坡牛角破坏模型上,采用极限分析上限定理计算边坡破坏时的外力功率和内能耗散率,根据虚功率原理推导三维边坡稳定系数的解析解,并运用穷举法得到稳定系数最优上限值。研究结果表明:在不考虑饱水软化效应情况下,与已有研究成果对比,结果吻合,验证文中方法的正确性;边坡三维效应(纵向尺寸效应)显著影响砂质泥岩边坡的稳定性,宽高比B/H增大意味着边坡纵向长度变长,边坡三维效应在逐渐弱化,当宽高比B/H≥6时,三维砂质泥岩边坡稳定性可视为一个二维平面应变问题;饱水软化效应、孔隙水压力效应明显降低三维砂质泥岩边坡的稳定性,饱水时间t=2月是三维砂质泥岩边坡趋于稳定的一个关键时间点;削坡可以有效提高三维砂质泥岩边坡的稳定性,兼顾安全性与经济性,饱水软化效应下的三维砂质泥岩边坡设计坡角以35°~50°为宜;边坡三维效应、饱水软化效应、孔隙水压力效应、削坡效果四者之间存在一定联系。研究成果可为饱水软化效应下三维岩质边坡稳定性分析提供参考。The influences of saturation softening and pore water pressure on the stability of3D slopes of sandy mudstone were investigated.The uniaxial compressive strength of rock mass with different saturation time was introduced into the Hoek-Brown strength criterion.The pore water pressure was regarded as an external force acting on a 3D horn failure model of rock slopes.The external work and internal energy dissipation rates were calculated using the upper bound theorem,the analytical solution of the stability factor of 3D slopes was deduced based on the virtual work principle,and the optimal value of the stability factor was obtained via the exhaustive method.The results show that,without considering the effect of saturated softening,the results of this study are in good agreement with the existing results,validating the correctness of the proposed method.The stability of slopes of sandy mudstone is significantly affected by the longitudinal dimension effect.The increase of the ratio of width to height B/H means that the longitudinal length of slopes becomes longer,and the 3D effect of slopes is gradually weakened.When the B/H≥6,the 3D slopes of sandy mudstone can be regarded as a 2D plane strain cases.The effects of saturated softening and pore water pressure significantly reduce the stability of 3D slopes of sandy mudstone.A key time point for 3D slopes of sandy mudstone to stabilize is the saturation time t=2 months.Slope cutting can effectively improve the stability of 3D slopes of sandy mudstone.Considering both safety and economy,the reasonable slope angle of 3D slopes of sandy mudstone with the effect of saturation softening being considered should be 35°~50°.In addition,there are certain connections among the 3D effect of slope,the effect of saturated softening,the effect of pore water pressure and the effect of slope cutting.This finding can be referred to when analyzing the stability of 3D rock slopes subjected to the action of saturation softening.

关 键 词：砂质泥岩边坡 饱水软化效应 孔隙水压力效应 稳定系数 破裂面 

分 类 号：TU457[建筑科学—岩土工程]