三维盾构隧道开挖面极限支护压力数值及理论解

Three dimensional Numerical and Analytical Solutions of Limit Support Pressure at Shield Tunnel Face

摘要:

对盾构隧道开挖面稳定性进行三维弹塑性有限元数值模拟，获得了维持开挖面稳定最小极限支护压力随隧道埋深比及土体强度参数的变化特性.将极限支护压力值表示为土体粘聚力、上覆荷载、土体重度与其影响系数乘积的三项叠加，并通过数值模拟获得了各影响系数随隧道埋深比及土体内摩擦角的变化规律.利用数值模拟结果对三维楔形体模型进行对比验证，结果表明楔形体模型得到的各影响系数在规律上与数值模拟结果相符，但在数值上，土体重度影响系数与数值模拟结果更接近，而粘聚力和上覆荷载影响系数则存在一定偏差.

Abstract:

The elasto plasticity finite element method was used to study the face stability of shield tunnel in three dimensional condition, the relationship between the limit support pressures and the tunnel depth to diameter ratio and soil strength was obtained. The limit support pressure was rewritten as the summation of cohesion, overlying surcharge load and soil weight multiplied by their corresponding influence coefficients. The varying characteristics of influence coefficients with the friction angle of soil and tunnel depth to diameter ratio were obtained. A comparison with the numerical results validated the 3D wedge limit equilibrium model. Results show that the influence coefficient of soil weight obtained from 3D wedge model agrees well with numerical results, while the influence coefficients of soil cohesion and surcharge load deviate from the numerical results slightly.