含水软弱夹层地下洞室稳定性模型试验研究

Model Test Study on the Stability of Underground Caverns in Soft Interlayer with Water

软弱夹层是影响岩体稳定性的重要薄层,是造成工程灾害的原因之一,研究其特征具有重要工程意义。为探索软弱夹层特征对地下洞室稳定性的影响,以夹层含水状态、夹层位置和夹层厚度为因素,通过自研的杠杆式平面应力模型试验系统进行多工况对照模型试验,分析了不同工况下开挖和蠕变试验阶段洞周各测点的应力和表面收敛变形量的变化规律。试验结果表明:进行开挖时,开挖轮廓正上方测点的垂直应力下降,临近洞肩测点应力上升,离洞室越远,开挖影响越小;开挖结束后,应力呈增加趋势,动态调整幅度减小,最终趋稳;洞室开挖时,模型表面洞周各测点主要表现为竖直收敛变形,开挖贯通后,依然是竖直收敛变形为主;开挖试验阶段和蠕变试验阶段,软弱夹层特征对地下洞室稳定性的影响程度为:软弱夹层含水状态>软弱夹层位置>软弱夹层厚度。在具有软弱夹层的地下洞室工程,特别是软弱夹层含水时,应采取疏通排水等措施控制软弱夹层对地下洞室稳定性的影响。

Soft interlayer is an important thin layer that affects the stability of rock mass and is one of the causes of engineering disasters, and the study of its characteristics has important engineering significance. In order to investigate the influence of water-bearing soft interlayer on the stability of underground cavern chamber, a multi-conditions control model test was conducted by the self-researched lever-type plane stress model test system, taking the water-bearing state of interlayer, interlayer location and interlayer thickness as factors, and the change law of stress and surface convergence deformation of each measurement point around the cavern in the excavation and creep test stages under different working conditions was analyzed. The test results show these follows. When excavation is carried out, the vertical stress at the measurement point directly above the excavation profile decreases, and the stress at the measurement point near the shoulder of the hole increases, and the further away from the cavern, the smaller the influence of excavation. After the end of excavation, the stress tends to increase, and the dynamic adjustment magnitude decreases and finally stabilizes. When the cavern is excavated, the measurement points around the cavern on the model surface mainly show vertical convergence deformation, and after the excavation is completed, the vertical convergence deformation is still dominant. During the excavation in the test phase and creep test phase, the degree of influence of weak interlayer characteristics on the stability of underground cavern chamber is: water content state of weak interlayer > location of weak interlayer > thickness of weak interlayer. In the underground cavern project with weak interlayer, especially when the weak interlayer contains water, measures such as dredging and drainage should be taken to control the influence of the weak interlayer on the stability of the underground cavern.