土岩复合地层盾构地中对接法刀盘拆卸不完全拱压力计算  

Calculation of pressures on after incomplete arch cutterhead removal in earth-rock composite formation by in-situ junction method for shield tunneling

作　　者：陈星欣[1] 何明高 施文城 郭力群[1] CHEN Xingxin;HE Minggao;SHI Wencheng;GUO Liqun(School of Civil Engineering,Huaqiao University,Xiamen 361021,China)

机构地区：[1]华侨大学土木工程学院,福建厦门361021

出　　处：《岩土工程学报》2024年第12期2652-2660,共9页Chinese Journal of Geotechnical Engineering

摘　　要：采用“相向掘进、地中对接、弃壳解体”的盾构地中对接法时,确保刀盘拆机后临空面稳定性是安全对接的关键。依托青岛盾构对接工程,通过COMSOL Multiphysics建立数值模型,基于主应力矢量流线偏转和各向应力变化确定盾构地中对接段压力拱主拱圈范围,并通过考虑大主应力不完全偏转和内摩擦角不完全调用推导上覆围岩压力计算公式。结果表明:盾构对接段沿隧道轴向的大主应力未见矢量流线成拱,沿隧道径向的成拱效应更为显著。由于拱顶存在松动区域,内边界并未与隧道上边沿重合,而是向上发展至拱顶一定高度,压力拱两侧边界倾斜向上,主拱圈整体呈现为盆状。对比不完全拱的大主应力实际偏转情况发现圆弧、线性、抛物线形拱迹线均高估了大主应力偏转角度,导致侧压力系数偏大,计算上覆围岩压力时偏于不安全,调用内摩擦角则随着距拱顶距离的减小而增大,通过数值模型计算和理论分析得出在压力拱作用下临空面荷载下降为初始围压的1/3。It is the key to ensure the stability of the free face after the cutterhead is disassembled by using the shield junction method of"junction,shell abandoning and disintegration in opposite tunneling".For a shield tunneling project in Qingdao,a numerical model is established by COMSOL Multiphysics.Based on the streamline deflection of the principal stress vector and change of stresses in various directions,the range of the main arch ring of the pressure arch in the junction section of the tunneling is determined,and the formula for calculating the overlying pressures on the surrounding rock is derived by considering the incomplete deflection of the major principal stress and the incomplete call of the internal friction angle.The results show that the major principal stress along the tunnel axis does not arch along the vector streamline,but the arching effects along the tunnel axis are more significant.Due to the loose area at the vault,the inner boundary does not coincide with the upper edge of the tunnel,but is a certain height away from the vault.The boundaries at both sides of the pressure arch are inclined upward,and the main arch ring is generally in the shape of a basin.By comparing the actual deflection of the major principal stress of incomplete arch,it is found that the arc,linear and parabolic arch traces all overestimate the deflection angle of the principal stress,resulting in a large lateral pressure coefficient,and it is unsafe to calculate the overlying earth pressures,while the internal friction angle increases with the decrease of the distance from the arch vault.Through the numerical calculation and theoretical analysis,it is concluded that under the action of pressure arch,the loads on the free surface drop to 1/3 of the initial confining pressures.

关 键 词：盾构对接 不完全拱 上覆压力 拱迹线 偏转 

分 类 号：TU43[建筑科学—岩土工程]