【摘要】 松动区是控制地下洞室围岩变形及失稳的重要因素。以锦屏一级水电站为例,结合声波测试及多点位移计监测成果,对高地应力和低强度应力比条件下大型地下厂房围岩松动区的分布及变化特征进行分析,并采用BP网络和遗传算法对围岩参数进行反演。研究表明,声波测试的围岩松弛深度与多点位移计监测得到的围岩主要变形深度具有一致性,围岩松弛深度变化趋势与岩壁位移变化也存在对应关系,两者结合可以对围岩松动区的变化规律进行连续的分析。高地应力和低强度应力比条件下的松动区深度远大于一般应力条件,由于围岩应力状态调整、岩体破坏所导致的卸荷松弛成为围岩松弛的主要因素。开挖过程中,由于围岩应力状态的逐步调整,导致围岩的破坏和松弛的渐进发展,其中松弛深度在水平向的扩展较为明显。反演得到的松动区岩体变形模量及黏聚力较未松动岩体有明显降低,而摩擦角降低较少。因此,对松动区岩体进行灌浆加固,将有助于提高松动区岩体的变形模量和粘聚力,从而增强围岩的稳定性。更多还原

【Abstract】 Excavation damaged zone (EDZ) is an important factor to the deformation and stability of underground caverns. Taking JinpingⅠHydropower Project for example, the distribution and variation of EDZ for large scale underground powerhouse under the conditions of high geostress and low strength-to-stress ratio are analyzed according to sonic wave measuring and multipoint extensometers monitoring; and the parameters of rockmass are back analyzed by BP network and genetic algorithm. The analytical results indicate that the depth of EDZ obtained by sonic wave measuring is consistent with the main deforming depth obtained by multipoint extensometers; and the depth change of EDZ is corresponding with the surface displacement change of rockmass; therefore the variation of EDZ can be analyzed continuously by the integrated using of sonic wave measuring and multipoint extensometers monitoring. Under the condition of high geostress and low strength-to-stress ratio, the depth of EDZ is much larger than general stress condition; and the unloading relaxation becomes the main factor of surrounding relaxation. The depth of EDZ increases with the stress adjustment of surrounding rock during excavating, in which the horizontal extending of EDZ is obvious. The deformation modulus E and cohesion c of EDZ carried by back analysis is markedly lower than undamaged rockmass, while the reducing of friction angle φ is less. Therefore, the grouting reinforcement of damaged rockmass will be benefit to improve its deformation modulus and cohesion; and the stability of surrounding rockmass will be improved consequently.更多还原