摘要
在脆性岩体地下工程开挖损伤区中,由应力导致的围岩损伤破裂占据主要地位。基于地下洞室开挖破坏数据库,修正了Kaiser等人提出的预测硬岩损伤区深度的经验公式,通过考虑原位应力比的影响,修正后的经验公式在拟合优度和预测准确性方面均有了一定程度的改善。为进一步研究开挖损伤区的范围及影响因素,提出了起裂判据CIC作为损伤区的力学表征指标,经对比验证,采用CIC判别的损伤区深度与经验公式预测值及现场实测值较为吻合,表明CIC作为损伤区表征指标具有较好的可行性;在CIC基础上,分析了洞室形状、方位对围岩诱发应力和损伤区范围的影响,研究表明,在高地应力场条件下,"谐洞"并不是最合理的洞形,而通过在小主应力方向上设置小曲率半径,可将高压缩应力限制在局部范围内,从而避免洞室围岩大范围的损伤破裂。相关认识和结论具有一定理论和工程意义。
The stress-induced excavation damage occupies the main position in brittle rock mass of underground engineering. Based on the excavation damage database of underground opening, the empirical formula for damage depth of hard rock put forward by Kaiser is revised. By considering the effect of the initial stress ratio, the revised empirical formula is improved with a certain extent in the goodness of fitting and prediction accuracy. For further studies on excavation damage zone and its influencing factors, the crack initial criterion (CIC) is put forward as the mechanical index for damage zone. It is found that the damage depth assessed by CIC is coincident with the predicted values by the empirical formula and filed measured values, indicating that CIC as the index for damage zone has good feasibility. On the basis of CIC, the induced stress and damage range of the surrounding rock are analyzed under different opening shapes and orientations. It is shown that the "Harmonious hole" is not the most reasonable shape under high stress field. By setting a small radius of curvature in the minor principal stress direction, the high compression stress can be limited within a local scope, and thus a wide range of surrounding rock damage of underground engineering can be avoided. The related understanding and conclusions are of certain theoretical and engineering significance.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2016年第S2期190-197,共8页
Chinese Journal of Geotechnical Engineering
基金
国家重点基础研究发展计划("973")项目(2015CB057905)
NSFC-云南联合基金重点支持项目(U1402231)
国家自然科学基金面上项目(51279202)
