库尉输水工程富水土质洞段的流固耦合分析

Fluid-solid Coupling Analysis of Water-riched Soil Tunnel for the Kuyu Water-transportation Project

库尉输水隧洞前段位于库鲁克山北侧倾斜砾质平原区,地下水位埋深较浅(最浅处仅为1.4 m),且远高于设计洞顶,给设计和施工带来了巨大的困难和挑战。在深入分析水文地质条件的基础上,采用大型有限差分软件FLAC3D对3个典型断面进行了流固耦合分析。研究表明,地下水对隧洞受力及变形特性影响显著,耦合条件下低液限粉土洞段拱顶变形约为不考虑渗流影响时的5.6倍,且与实测值更为接近;不同围岩类型和水文地质条件下各洞段的变形差异较大,耦合条件下低液限粉土洞段的拱顶变形为90 mm、而粉土夹砂和粉细砂夹砾石洞段的变形分别为36 mm和26 mm;耦合条件下各典型断面支护结构受力均超过了素喷混凝土的设计抗拉强度(1.1 MPa),需尽快施做二次衬砌。以上研究成果可为本工程及类似工程的设计与施工提供参考。

The front part of Kuyu water-conveyance tunnel is located in the gravel plains of the north Kuluke mountain,where the groundwater level is very shallow（the shallowest is only 1. 4 m） and far above the tunnel roof. So the groundwaterr brings tremendous tragedy and challenge to the tunneling design and construction. Based on deep analysis of hydro-geological conditions,the fluid-solid coupling characteristics of several typical models of this tunnel was studied using three-dimensional finite-difference software-FLAC3 D. It shows that the groundwater has a significant effect on the deformation properties of this tunnel. The vault settlement under coupling condition is approximately 5.6 times as that without considering the seepage effect and it is closer to the field test data. There is greater difference for the deformation of different alternatives under coupling condition,which has different country rocks and groundwater conditions. The vault settlement of low liquid limit silt is 90 mm,and that for the stratum of silt-sandmark and fine silt with gravel is 36 mm and 26 mm,separately. The spray stress of the different alternatives in coupling condition are greater than the design strength of plain concrete,so the secondary lining should be applied as soon as possible. The research results have certain reference values for this and similar project.