大断面黄土隧道工程特性研究

Research on Characteristics of Large-Section Loess Tunnel Project

较之常规隧道,大断面黄土隧道因其断面和跨度大而具有很强的非线性力学行为。基于现场调查与室内三轴试验曲线分析,指出具有结构性强度及垂直节理是黄土围岩的2大特点。根据黄土的折线型结构强度曲线推导弹塑性应力分区理论公式,分析支护阻力、强度比、跨度等对大断面黄土隧道的影响规律。依据可考虑结构性强度与垂直节理的双线性遍布节理模型,对深、浅埋大断面黄土隧道进行数值仿真,探讨其位移形态与破坏模式。研究成果对于实际工程具有指导意义。

Comparing with conventional tunnels, the large-section loess tunnels have strong nonlinear mechanical behaviors due to large-section and large-span. Based on field investigation and analysis on indoor triaxial test curves, this paper points out the structural strength and vertical joints are two features of loess wall rock. The paper derives the theoretical formulae for partition of elastic and plastic stresses based on broken line type structural strength and analyzes the principles of influences of supporting resistance, strength ratio and span, etc. on large-section loess tunnels. In accordance with the double linear model of pervasive joints for considerable structural strength and vertical joints, the paper carries out the numerical simulation for deep and shallow buried large-section loess tunnels and probes into the shapes of displacement and failure modes. The achievements of research have instructive significances to practical projects.