摘要
为了研究滇中红层软岩地质条件下引水隧洞开挖后节理岩体的应力、变形以及塑性区特征,以云南省禄丰市大地箐东侧引水隧洞工程区为例,结合现场水压致裂法地应力测试数据,分析了引水隧洞围岩发生岩爆的可能性,并运用MIDAS/GTS NX有限元模拟软件,以节理为主要影响因素,研究了隧洞开挖后围岩的稳定性。结果表明:最大水平主应力σh1测试值的范围为3.74~15.52 MPa,属于中等-低地应力范围,σh1方向为N15°~41°W,研究区受到NNW-NW方向的地应力作用;引水隧洞附近围岩强度应力比Rb/σm为5.2,属于4~7之间,可能会出现轻微岩爆,建议采取洒水的方式软化开挖面表层,并加强支护;数值模拟得出隧洞洞壁压应力和拉应力最大值分别为19.5 MPa、4.34 MPa。顶拱下沉位移最大值为1.00 cm,底拱隆起位移最大值为0.55 cm。塑性区分布在隧洞侧墙,深度范围在0~1 m之间。节理裂隙的发育对隧洞围岩稳定性产生了不利的影响,隧洞存在顶拱围岩在结构面组合影响下产生掉块的风险,左右侧墙围岩也可能会发生潜在的破坏。因此,建议对顶拱和左右侧墙围岩进行加固。研究结果可为滇中红层软岩地质条件下的引水隧洞工程提供经验借鉴。
In order to study the characteristics of stress, deformation and plastic zone of jointed rock mass after excavation of diversion tunnel under soft rock geological conditions in middle red layer of Yunnan Province, the possibility of rock burst in surrounding rock of diversion tunnel was analyzed by taking the engineering area of east Earth leech diversion tunnel in Lufeng City, Yunnan Province as an example, combined with in-situ stress test data of hydraulic fracturing method, and MIDAS/GTS NX finite element simulation software was applied. With joint as the main influencing factor, the stability of surrounding rock after tunnel excavation is studied. The results show that the maximum horizontal principal stress σ_(h1) ranges from 3.74 to 15.52 MPa, which belongs to the range of moderate to low ground stress. The direction of σ_(h1) ranges from N15° to 41°W, and the study area is subjected to ground stress in the direction of NNW to NW. The strength stress ratio R_b/σ_m of surrounding rock near the diversion tunnel is 5.2, which is between 4 and 7, and there may be slight rock burst. It is recommended to soften the surface of the excavation surface by sprinkling water and strengthen the support. The numerical simulation results show that the maximum compressive stress and tensile stress of tunnel wall are 19.5 MPa and 4.34 MPa respectively. The maximum subsidence displacement of the top arch is 1.00 cm, and the maximum uplift displacement of the bottom arch is 0.55 cm. The plastic zone is distributed on the side wall of the tunnel, and the depth ranges from 0 to 1m. The development of joint fissure has an adverse effect on the stability of surrounding rock of the tunnel. The top arch surrounding rock of the tunnel has the risk of falling block under the influence of structural plane combination, and the surrounding rock of the left and right side walls may also have potential damage. Therefore, it is recommended to strengthen the top arch and the surrounding rock of the left and right side walls. The resear
作者
张松锋
古兴伟
刘皓
ZHANG Song-feng;GU Xing-wei;LIU Hao(Kunming University of Science and Technology,Kunming 650093,China;PowerChina Kunming Survey,Design and Research Institute Co.,Ltd.Kunming 650033,China)
出处
《地质灾害与环境保护》
2024年第4期78-85,共8页
Journal of Geological Hazards and Environment Preservation
关键词
滇中红层软岩
引水隧洞
水压致裂法
围岩稳定性
Middle red layer soft rock of Yunnan
diversion tunnel
hydraulic fracturing method
surrounding rock stability
