TBM引水隧洞组合结构联合承载特性及荷载分担率研究

Study on Combined Bearing Characteristics and Load Sharing Ratio of TBM Diversion Tunnel Composite Structure

为探究TBM引水隧洞在Ⅴ类围岩条件下组合结构联合承载特性影响及荷载分担率研究,基于有限元软件,依托榕江关埠引水隧洞工程,建立三维计算模型,开展管片的施工开挖及受力,对计算结果进行特性分析。结果表明:TBM隧洞施工开挖开始至结束地表的断面竖向沉降值逐渐增加,且开挖的开始和结束阶段是较为危险阶段,实际工程中应给予重视监测;组合结构联合承载中管片的竖向位移和最大压应力均小于管片单独承载,且外压工况下管片压应力最大,最大值为18.22 MPa,均满足相应的规范要求;外压控制下主要由管片承担荷载,钢圈和锚杆作为储备力分担荷载,其中管片平均承担93.06%,内张钢圈平均分担6.11%,锚杆平均分担0.84%。因此组合结构可为引水隧洞工程中管片的安全设计提供参考。

In order to explore the influence of the combined bearing characteristics of the TBM headrace tunnel under the condition of Class V surrounding rock and the study of the load sharing rate,based on the finite element software and relying on the Rong jiang Guan bu headrace tunnel project,a three-dimensional calculation model is established to carry out the construction excavation and stress of the segments,and the characteristics of the calculation results are analyzed.The results show that the vertical settlement value of the surface section gradually increases from the beginning to the end of the TBM tunnel excavation,and the beginning and end of the excavation are relatively dangerous stages,so attention should be paid to monitoring in practical projects;The vertical displacement and maximum compressive stress of the segment in the combined bearing of the composite structure are smaller than the segment alone bearing,and the maximum compressive stress of the segment under external pressure is 18.22MPa,which meets the corresponding specification requirements;Under the control of external pressure,the load is mainly borne by segments,and the steel ring and anchor bolt are used as reserve force to share the load,of which 93.06%is shared by segments,6.11%is shared by inner tensioned steel ring,and 0.84%is shared by anchor bolt.Therefore,the composite structure can provide a reference for the safety design of segments in the headrace tunnel project.