马蹄形断面引水隧洞开挖数值模拟与支护技术

Numerical simulation and support technology of horseshoe section diversion tunnel excavation

为研究不同围岩级别下,不同初期支护形式对围岩稳定性的影响程度。结合清原抽水蓄能电站引水隧洞,采取模糊物元法对围岩进行精细化分级,运用FLAC 3D分析3种初期支护因素影响下围岩的受力特性。结果表明:将模糊物元法应用于水利工程岩体质量分级可以有效避免现行规范中围岩级别跨度大、分级指标不相容等问题,为支护强度提供可靠基础。同时根据正交数值模拟试验设计的9种锚喷支护方案受力特性分析,得出在Ⅲ、Ⅳ类围岩下,采取马梯形断面腰部以下不使用锚杆支护形式,可将围岩应变控制在0~5 mm之间,相较于未支护时位移变形减少了90%左右;锚杆承受的轴向应力均控制在其承载能力范围内,满足安全支护。对比全断面支护形式更经济合理,为类似工程提供依据。

In order to study the influence degree of different initial support forms on the stability of surrounding rock under different levels of surrounding rock.Combined with the diversion tunnel of Qingyuan pumped storage power station,the surrounding rock was refined and classified by fuzzy matter-element method,and the mechanical characteristics of surrounding rock under the influence of three initial support factors were analyzed by FLAC 3D.The result show that the application of fuzzy mature-element method to rock mass quality classification in hydraulic engineering can effectively avoid the problems of large span of surrounding rock class and incompatibility of classification index in the current standard,and provide a reliable basis for support strength.At the same time,according to the analysis of the force characteristics of 9 kinds of bolt-shotcrete support schemes designed by orthogonal numerical simulation test,it is concluded that the strain of surrounding rock can be controlled between 0~5 mm when the horse trapezoid section is adopted below the waist without the use of bolt support,and the displacement deformation can be reduced by about 90%compared with that without the support.The axial stress of the bolt is controlled within the range of its bearing capacity to meet the safety support.Compared with full section support,it is more economical and reasonable,and provides basis for similar projects.