渡口坝坝肩采空区置换措施及加固效果研究

梅溪河渡口坝坝址处贯通于坝基砂岩中的煤层采空区是影响拱坝坝肩稳定的突出问题。为确定采空区开挖置换混凝土的深度,采用有限元分析方法,取正常蓄水位+温降时采空区置换50 m、80 m1、00 m和无置换的情况,对渡口坝坝体及基岩应力应变特性进行了计算分析,给出了各自的应力和位移分布,并开展相应处理方案的超载稳定计算分析。对比分析表明,坝肩煤层采空区对坝肩变位和应力分布影响显著,必需采取置换措施。与无置换时相关数据进行对比,置换深度达到80 m时,坝体蓄水期总体变形规律明显改善,上游坝面拉应力极值显著减小,坝体与坝基超载能力提高,满足设计要求。

The Replacement Measures and Study of Reinforcing Effects of the Coal Mined-out Area of Dukouba Dam Abutment

The coal mined out area in sandstone is an outstanding problem for Dukouba arch dam＇s abutment stability. To determine the concrete replacement depth of coal mined - out area in the abutment, this paper conducted numerical simulation by employing finite element method, and compared in detail the dam and deformation characteristics of Dujouba dam under operation condition of original foundation and the three reinforcement conditions, whose concrete replacement depths of coal mined out area are separately 50m, 80m and 100m during normal storage period. The comparison shows that the dam stress and deformation are strongly affected by the coal mined out area in abutment, reinforcement measures must be taken. Compared with the original foundation conditions, when the replacement depth reaches 80m, the distribution of dam stress and deformation have been significantly improved, the tensile stresses on upstream dam surface are decreased remarkably. The overload beating capacity of the dam and foundation are increased to meet the design requirements.