层状板岩隧道大变形控制参数优化数值模拟分析及现场试验

Optimization of large deformation control parameters of layered slate tunnels based on numerical simulation and field test

以木寨岭公路隧道为研究工程背景,木寨岭隧道是全线地质条件最差的隧道,其复杂性主要表现为:断层构造作用强烈、地应力高、隧道埋深较大、地下水发育等。隧道原支护设计下,出现了初支开裂、拱架破坏和围岩渗水等状况。经NPR锚网索支护策略施作,大变形支护控制效果显著,最大变形量为240 mm。为降低工程造价,提高施作效率,对NPR锚网索行间距进行优化设计,利用Flac3D内嵌的fish语言,建立具有高恒阻大变形的NPR锚索结构单元,对不同优化方案进行数值模拟,对比分析各种方案下模拟得出的各项正应力、剪应力及变形云图,再进行现场试验,将现场试验结果与数值解进行对比分析,认为小进尺开挖加NPR锚网索支护体系可能对松动圈产生影响,提出NPR锚网索支护设计的优化方向,为二次优化奠定理论和实践基础,同时该技术也为川藏铁路的实施奠定理论和实践基础。

Muzhailing tunnel,taken as the background of the research,has the worst geological condition in the whole line including strong fault tectonism,high ground stress,large depth and rich groundwater.Aiming at the damage phenomena of Muzhailing tunnel after first support such as initial support cracking,arch damaging and surrounding rock seepage,NPR bolt-mesh-cable support was applied and the deformation was successfully controlled with a maximum of 240 mm.In order to reduce the construction cost and to improve the construction efficiency,in this paper,the optimum design of the cable-line spacing of NPR anchor net was carried out.A structural element of NPR anchor cable with high constant resistance and large deformation was established by using Fish language of Flac3 D,and numerical simulations of different row spacing optimization schemes were implemented to compare the normal stress,shear stress and deformation nephogram under different schemes.Field tests were conducted,and the field test results were compared with the numerical solutions.It is shown that loose ring may be affected by small footage excavation and NPR anchor mesh cable support system.At last an optimal design direction of NPR anchor mesh cable support was proposed,which provides a theoretical and practical foundation for secondary optimization.The research gives a reference for the implementation of Sichuan-Tibet Railway.