中文摘要：

因地形地貌及工程间的相互影响,高密度地下洞室群的出现概率逐渐增大,洞群各洞室与洞群整体稳定性的关系、洞群的主导破坏模式、合理规划设计各洞室支护措施强度以实现等强度设计理念等课题研究的需求越加迫切。基于有限元强度折减理论,依托重庆某一大型高密度地下洞室群,对比现行安全系数主要判定准则在洞群应用中的可行性及合理性;基于最小二乘法,利用二次多项式对各洞室安全系数与二衬厚度的隐含关系进行显示拟合,并通过遗传算法对二衬厚度进行优化。洞室间夹层围岩等次要部位的局部破坏对洞室乃至洞群的整体稳定性影响较小。并行洞室的主导破坏模式与两者间距、埋深等因数有关,主要分为3种破坏模式：埋深较浅且洞间间距较大,洞室拱顶塑性围岩破坏区向背离洞群中心的斜上方发展并贯通至地表,洞群破坏;当埋深较深且洞间间距较小,各洞室拱顶塑性围岩破坏区向靠近洞群中心的斜上方交汇贯通,洞群破坏;当洞间间距及埋深均处于两种破坏模式之间时,上述两种破坏模式共同导致洞群破坏。洞群主导破坏模式多样,洞室关键点位移随强度折减系数的变化曲线不一定有明显的突变点,此时宜结合塑性区分布及其发展历程共同确定洞室安全系数。基于最小二乘法的二次多项式对隐含关系显示表达,利用遗传算法对洞群各二衬厚度进行优化,既可达到一定的拟合精度也能得到较理想的优化结果。

英文摘要：

Due to the restriction of topography and the interaction between related engineering,the probability of occurrence of high density underground caverns is increasing. The relationship between each cavern and the overall stability of the caverns,the dominant failure mode and how to design the strength of supporting measures of each cavern reasonably to realize the equal strength theory are becoming increasingly urgent. The feasibility and reasonability of the application of the main current criterion to gain safety factor in caverns were analyzed based on the theory of finite element strength reduction and some large high-density underground caverns in Chongqing. Based on the least square method,the relationship between the safety factor and the final lining thickness of each cavern is expressed through the quadratic polynomial and the thickness of each final thickness is optimized by the genetic algorithm. The local failure of the secondary parts such as the surrounding rock between caverns influences little on the stability of each cavern or caverns. The dominant failure modes of parallel caverns can be classified into three categories determined by many factors such as the distance between them and the embedded depth. When the embedded depth is shallow and the distance is large,the plastic region near the vault of each cavern grows upward to the surface in the direction opposite to the center of the caverns and finally results in failure. When the embedded depth is deep and the distance is small,the plastic region near the vault of each cavern grows upward in the direction to the center of the caverns and finally results in failure. When the embedded depth and the distance are in moderate sizes,the above two failures contribute to the failure together. For the various dominant failure modes of caverns,the curves depicting the relationship between the displacement of key points and the strength reduction factor may be less obvious and the distribution and development process of plastic zone should be resorted to