北盘江电站地下厂房群施工过程数值分析

Numerical Simulation of the Excavation Process of Beipan River Hydropower Station Underground Caverns

以北盘江一级水电站地下厂房群为例,依据工程区区域地质条件与水文地质条件并结合实际开挖方式与开挖顺序,成功地在ADINA中实现了三维仿真数值模型的建立。采用应力试算法对模型边界处初始地应力进行拟合,在分析区域构造特征、现场实测数据和前期研究成果的基础上,通过对重力场模型的竖向边界上同时施加水平方向对称梯度应力,所取得的拟合效果最佳。洞室开挖完成后,洞周块体的水平位移均指向下游;围岩位移收敛速度较快,时效特征不显著。由于顶部局部软弱带的影响,致使该区洞室围岩变形稍大,但洞室整体稳定状况良好。最后,将位移现场监控数据与模拟结果进行了对比分析,结果说明所建模型可靠度高,可为洞室设计提供科学依据与技术指导。

Based on Bei Pan River hydropower station underground cavities and its engineering geological conditions and hydrogeological conditions,adopting reasonable methods and sequence for excavation with actual situation,a three dimensional finite element analysis model is established in ADINA. In the model of gravity field,the best fitting effects can be got if the symmetric gradient stresses are exerted on the vertical boundaries of the two horizontals after many trials and analyzing the geotectonic characteristics,the testing data and research results of this zone.The anchor was simulated by truss element and the concrete spray layer was simulated by shell element,excavation mechanical behaviors of the caverns were analyzed. Results show the distribution of displacement and stress.Displacements of all the blocks around the cavern are pointing to the downstream when excavation is completed.Deformation of surrounding rock mass reduces quickly. The time characteristic of the surrounding rock displacement is not noticeable,and the stability of the cavities is good. As for several weak intercalations are adjacent to the underground caverns, displacement displays a typical characteristic step rise with the excavation process, the deformation of intercross between cavern and weak intercalations is large. Finally,the numerical model built with high reliability is provided through comparing field measuring data and calculation results. It can provide a reference for other such problems using ADINA and provide scientific basis and technical advice for caverns design.