摘要
针对高地应力环境下缓倾层状隧道围岩的挤压变形问题,以云南昭乐高速轿顶隧道为工程背景,通过已开挖洞段底板的水压致裂试验,反演了初始地应力场;基于强度应力比大变形分级标准,对围岩挤压变形情况进行了预测分析;最后结合现场围岩变形破坏特征,探讨了深埋缓倾层状围岩挤压大变形的控制措施。研究表明:在测量深度范围内,水平主应力和垂向应力均随深度线性增加,最大水平侧压系数为1.52~1.80,最小水平侧压系数为0.91~1.10,即工程区内水平应力占主导作用,且最大水平主应力方位为NW294°,与区域构造应力场主压应力方向基本一致;测试区段内围岩的强度应力比均小于4,即围岩初始地应力均处于极高地应力状态;强度应力比计算结果表明,围岩的变形以轻微(Ⅰ级)至中等(Ⅱ级)大变形为主,但考虑到缓倾层状节理发育,且部分区段围岩极为破碎,有很大可能出现强烈(Ⅲ级)大变形;双层初支与注浆加固能有效控制拱顶沉降与仰拱隆起。
On the background of Jiaoding Tunnel of Zhaole expressway in Yunnan,the issue of the compressional deformation of the gently dipping layered tunnel surrounding rock under high in-situ stress was addressed.The initial in-situ stress field was inverted through the hydraulic fracturing tests at the floor of the excavated tunnel.Subsequently,the compressional deformation of the surrounding rock was forecasted and analyzed using the strength-stress ratio-based deformation grading standard.Finally,the control measures of the compressional deformation of the deep-buried gently dipping layered surrounding rock were discussed on account of the deformation and failure characteristics of the surrounding rock.The results indicate that the horizontal principal stress and vertical stress both increase linearly with the depth within the measuring depth range.The maximum horizontal lateral pressure coefficient is 1.52~1.80,while the minimum horizontal lateral pressure coefficient is 0.91~1.10.The horizontal stress is dominant in the engineering area,and the maximum horizontal principal stress orientation is NW294°,which is the same as the principal compressive stress direction of the regional tectonic stress field.The strength-stress ratios of the surrounding rock in the testing section are all less than 4,which implies that the initial in-situ stress belongs to the extremely high stress state.The calculation results of strength-stress ratio show that the deformation grade of the surrounding rock should be mainly the slight(Level-I)to medium(Level-II)level.However,the deformation grade might well be the strong level(Level-III),considering the development of the gently dipping layered joints and the exiting of some extremely broken surrounding rocks.The double-layered initial support and grouting reinforcement can effectively reduce the settlement of the arch crown and the uplift of the arch bottom.
作者
王亚琼
杨强
高启栋
王世业
张士朝
Wang Yaqiong;Yang Qiang;Gao Qidong;Wang Shiye;Zhang Shichao(School of Highway,Chang'an University,Xi'an 710064,P.R.China;Key Laboratory for Bridge and Tunnel of Shaanxi Province,Chang7an University,Xi'an 710064,P.R.China)
出处
《地下空间与工程学报》
CSCD
北大核心
2022年第2期562-576,共15页
Chinese Journal of Underground Space and Engineering
基金
国家自然科学基金(41702287)
陕西省自然科学基础研究计划(2021JQ-258)
中央高校基本科研业务费专项(300102210123)。
关键词
高地应力
缓倾层状围岩
水压致裂试验
挤压变形分级
双层初支
注浆加固
high in-situ stress
gently dipping layered surrounding rock
hydraulic fracturing test
grading of compressional deformation
double-layered initial support
grouting reinforcement
