向家坝大型地下厂房长期稳定性研究

对地下洞室的长期观测和量测都表明,许多在成洞之初呈现稳定的岩体,由于变形随着时间推移而不断发展,经过一段时间之后,洞体可能失稳或坍塌破坏,特别是大型地下洞室,地质条件复杂、开挖时间长、扰动大,其长期稳定性更值得关注。向家坝地下厂房为一超大型地下洞室,开挖跨度在国内外已建、在建和拟建的水电站中居第一,其跨度和规模均居世界前列。洞室围岩地质条件复杂,岩性较差,有不稳定块体,地下水较为丰富,岩石透水性较好,且夹杂有多条软弱夹层,对地下厂房长期运行不利。基于此,通过试验得到了地下厂房围岩的长期强度;结合实际工程中常用的变形和流变速率,提出了洞室最佳支护时间、长期稳定流变时间、最大流变变形的判据;对洞室支护措施进行了模拟,对其支护效果进行了评价。经过总结分析,得到了对工程有指导性的结论。

Study on the Long-Term Stability of Large-Scale Underground Plant of Xiangjiaba Hydropower Station

It’s indicated by long-term observation and measurement in underground cavern that rock mass which is stable at the beginning of the cavern construction may be unstable or collapsed and damaged due to its progressive deformation. Special attention should be paid to large-scale underground caverns because of complicated geological conditions, long period of excavation and large disturbance. The underground plant of Xiangjiaba hydropower station is a super large-scale underground cavern. Its span is ranked No.1 among all the constructed and being constructed hydropower stations in the world. The complicated geological conditions, poor quality of rock mass, unstable rock block, rich groundwater, good permeability and multiple weak interlayers, are adverse to long-term operation of underground plant. From this point of view, the long-term strength of surrounding rocks in the underground plant is obtained by the laboratory creep tests.The criteria of the optional supporting time, the long-term stable rheological time and the maximum rheological deformation are proposed based on the deformation and deformation rate frequently used in practical engineering. The supporting measures are simulated in order to assess the supporting effects. The results could be used to provide an important reference for the project.