复合地层泥水土压双模盾构模式合理转换点位置研究

Study on the Reasonable Conversion Point Position of the Dual-Mode Slurry/Soil Pressure Shield in Composite Formation

依托向家坝灌区北总干渠猫儿沱江底隧道工程,从安全性角度出发研究泥水/土压双模盾构模式合理转换点选取原则。基于渗透系数和水位高度建立不同工况流固耦合数值模型,分析各工况下拱顶沉降、掌子面挤出变形和掌子面渗流量变化规律,最终确立泥水/土压双模盾构在不同工况下的合理转换点位置。结果表明:泥水/土压双模盾构模式转换过程掌子面稳定性为关键控制因素,转换点位置应选择在与地层交界面有一定距离的稳定地层中;地层之间渗透系数差异越大,掌子面挤出变形和掌子面渗流量越大,而拱顶沉降略有减小;掌子面挤出变形、掌子面渗流量和拱顶沉降均随水位高度增大而增大。研究结果可为泥水/土压双模盾构模式转换提供参考。

Relying on the Maoertuo River bottom tunnel project of the section of the North Main Canal in Xiangjiaba Irrigation Area,the principle of selecting the reasonable conversion point of dual-mode slurry/soil pressure shield was studied from the perspective of safety.Based on the permeability coefficient and water level height,the numerical model of fluid-structure coupling under different working conditions was established,and the change laws of vault settlement,tunnel surface extrusion deformation and tunnel surface seepage flow during excavation under different working conditions were analyzed,finally,the position of the reasonable conversion point of the dual-mode slurry/soil pressure shield under different working conditions was established.The results show that the stability of the tunnel surface is the key control factor during the conversion of dual-mode slurry/soil pressure shield machine,and the location of the conversion point should be selected in a stable formation at a certain distance from the strata interface.The greater the difference in permeability coefficient between formations,the larger the extrusion deformation and the seepage flow at the tunnel face,while the slight decrease of vault settlement.The extrusion deformation of the face,the seepage flow of the face and the settlement of the vault all increase with the increase of the height of the groundwater table.The research results can provide some reference for the mode conversion of dual-mode slurry/soil pressure shield machine.