双斜滑动面地基对胶凝砂砾石坝破坏模式的影响研究

为探究复杂地基对胶凝砂砾石坝(CSG坝)安全稳定性的影响,对均质地基、断裂双斜滑动面地基和完全发育双斜滑动面地基上的CSG坝开展了三维地质力学模型试验研究。通过分析试验中坝体、坝基的变形特征,以及模型的破坏过程与破坏形态,探究了影响坝体安全稳定的控制性因素。研究结果表明:(1)均质地基模型、断裂双斜滑动面地基模型和完全发育双斜滑动面地基模型的超载安全系数K_p分别为6.8、6.4和6.0。(2)模型的破坏模式与地基整体性有很大的关系,其由坝体沿坝基面产生的贯通裂缝破坏,逐渐发展为跟随地基中的滑移通道滑动,形成坝踵下降、坝趾抬升的滑动翻转破坏。(3)复杂地基中结构面的抗滑稳定性决定着CSG坝的稳定性;CSG坝在受到双斜滑动面地基影响后,各模型的破坏超载安全系数随着地基的发育逐步降低,严重影响着工程安全性,在坝址选取时应尽量避免可能形成潜在滑动面的危险断层。试验成果可对CSG坝后续发展、设计及施工提供参考依据。

Study on the influence of double-slope sliding surface foundation on the failure mode of cemented sand and gravel dam

In order to explore the influence of complex foundation on the safety and stability of cemented sand and gravel dam(CSG dam),three-dimensional geomechanical model tests were carried out for CSG dam on homogeneous foundation,fractured double-slope sliding surface foundation and fully developed double-slope sliding surface foundation.By analyzing the deformation characteristics of the dam body and dam foundation,the failure process and failure mode of the model in the experiment,the controlling factors affecting the safety and stability of dam body are explored.The results show that:(1) the overload safety factor K_p of homogeneous foundation model,fractured double-slope sliding surface foundation model and fully developed double-slope sliding surface foundation model are 6.0,6.4 and 6.8,respectively.(2) The failure mode of the model has a great relationship with the integrity of the foundation.The failure mode of the dam body is caused by the through crack along the dam foundation surface,and gradually develops into the sliding channel sliding in the foundation,forming the sliding flip failure of the dam heel falling and the dam toe lifting.(3) The stability of CSG dam is determined by the anti-sliding stability of structural plane in complex foundation.After the CSG dam is affected by the double-slope sliding surface foundation,the overload safety factor of each model gradually decreases with the development of the foundation,which seriously affects the safety of the project.It is necessary to avoid the dangerous faults that may form the potential sliding surface when selecting the dam site.The test results can provide reference for the subsequent development,design and construction of CSG dam.