土坝水力劈裂的离心模型试验及其分析

Centrifuge model test of hydraulic fracture of earth dam and it's analysis

本文介绍了深截水槽心墙砂壳坝的离心模型试验及其有限元数值模拟的结果．截水槽两侧的混凝土基座内设有水管，以模拟Ｔｅｔｏｎ坝基岩内裂隙的作用．数值分析用有效应力法，同时采用双屈服面弹塑性模型和损伤断裂模型．分析所得的应力和变形与实测值有一定出入，但两者的基本趋势一致．试验与分析结果均表明，虽然截水槽内拱效应很明显，但兀水力劈裂迹象．由此得出结论，深截水槽心墙坝并不见得一定有水力劈裂的危险，流行的总应力判别法过大估计了水力劈裂的可能性．

In this paper the possibility of hydraulic fracture of an earth dam with deep cut-off wall is studied by centrifuge model test and finite element analysis The fissured bedrock as that encoutered in Teton dam which was'failed in 1976 is modeled by a concret mass and a tiny pipe is buried to divert the water from reservoir.The numerical analysis is based on the effeCtive stress approach.In spite of notable arch effect on the cut-off wall, neither hydraulic fracture was observed in the model test nor a low stress zone with tensile effective stress has been detected in the FEA.Therefore,It is concluded that the total stress approach for hydraulic fracturing criterion used to predict the occurence of hydraulic fracture overestimates the possibility of hydraulic fracture.