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针对引水隧洞地质条件复杂、岩性差异大的特征,建立仿真三维模型,采用Mohr-Coulomb弹塑性本构模型,以分段开挖方式,对比纯开挖、支护开挖围岩径向位移、应力响应差异,分析研究隧洞穿越大型断裂带过程中的围岩力学行为。结果表明,断裂带右侧初始自重应力明显偏低,附近石灰岩段存在应力集中现象,开挖后断裂带左侧洞顶径向位移明显大于右侧;纯开挖时,已开挖部分洞壁径向应力趋于零,掌子面前方约3倍洞径范围应力释放与应力集中现象突出,各分段掌子面附近出现径向位移极小值点;开挖支护时,已开挖部分洞壁径向应力维持在较高水平,处于三向压缩状态,掌子面前方应力集中现象减弱,在各分段开挖掌子面前方应力释放区内,径向应力极小值点和径向位移极大值点一一对应,间接反映支护时机对围岩力学响应的影响。研究成果可为引水隧洞施工提供指导。
In view of the complex geological conditions and large difference in lithology of the diversion tunnel, a three-dimensional simulation model is established. The Mohr-Coulomb elastic-plastic constitutive model is adopted to compare with the pure excavation and radial excavation , Stress response differences, analysis of the tunnel through the large fracture zone in the process of mechanical behavior of the surrounding rock. The results show that the initial self-weighting stress on the right side of the fault zone is obviously low, and the limestone section nearby has stress concentration. After the excavation, the radial displacement on the left side of the fault zone is obviously larger than that on the right side. When pure excavation, The radial stress tends to zero, stress release and stress concentration are prominent in the area of about 3 times of the diameter of the front of the face, and the minimum value of radial displacement appears near the face of each segment; when digging and supporting, it has been excavated Part of the cave wall radial stress is maintained at a high level in a three-dimensional compression state, the front of the face of the stress concentration is weakened in the face of each section excavation stress release zone before the face, the minimum point of radial stress and Radial displacement maximum point one-to-one correspondence, indirectly reflects the timing of the support of the surrounding rock mechanical response. The research results can provide guidance for diversion tunnel construction.