地下洞室围岩裂隙开裂判断方法及其应用

Crack Expansion Judgment Method for Wall Rock of Underground Caverns and Its Application

针对深部地下施工过程引起结构围岩损伤的现象,提出了可模拟裂隙开裂的新方法。根据断裂力学Griffith理论和经典的强度理论Mohr-Coulomb准则,得出材料在剪切和拉伸条件下裂隙开裂的判据;并且以离散元程序UDEC3.1为基础,应用其内嵌的FISH语言对软件进行二次开发,将该判据耦合到计算过程中。数值计算中,在UDEC块体(BLOCK)内部预设潜在节理面,根据潜在节理面的受力状态,依据判断准则判断节理面的开裂与否,节理开裂后利用其内嵌的节理模型(库伦滑动模型)模拟岩体中节理面的变形性质。把上述计算方法应用于某地下洞室群稳定性分析中,模拟在洞室开挖过程中,洞室围岩的裂隙扩展过程及其扩展状态,根据裂隙扩展情况来分析地下洞室围岩和结构的稳定性,有效的进行围岩支护,以确保洞室结构的稳定性;并将最终计算的位移结果与现场多点位移计的监测结果进行对比,二者吻合良好,验证了该计算方法的有效性。

With the execution of some important items, many huge underground structures will be constructed. The underground construction process usually involves damages to the rock wall of underground structures, even the crack expanding and the breakage of the structure. Aiming at these instances, a new method for modelling the crack expansion is developed in this paper. The crack expansion judgment method under the state of the tension and the shear is developed according to the Griffith law of fracture mechanics and the Mohr - Coulomb law of the classical strength theory. Based on them, the secondary exploitation of the 2 - dimensional distinct element program （ UDEC3. 1 ） is carried out in virtue of the inner - embed FISH language. Through the secondary exploitation, the above judgment law is coupled into the UDEC computation to implement the crack expansion judgment. In the computation, some potential joints are beforehand inserted in the UDEC deformable block around the excavation. After the potential joints craze, the inner- embed joint model of Coulomb slip is selected to simulate the behavior of the joints in the rockmass. The above program is applied to analyzing the ground movement when the underground powerhouses are installed in the jointed rockmass. To verify its validity, the obtained numerical results are compared with the in - situ monitoring ones. They are in good agreement.