软土地区类矩形盾构隧道同步注浆填充扩散压力空间分布模式

为解决类矩形盾构隧道同步注浆时易发生的浆液淤积问题,研究浆液在类矩形盾构隧道盾尾间隙内的填充扩散过程.根据流体力学原理,推导浆液在宾汉姆流体条件下的压力环纵向分布模式,得到软土地区类矩形盾构隧道同步注浆环向填充与纵向扩散的力学模型及计算方法;结合宁波市轨道交通3号线陈婆渡车站出入段线隧道工程实测数据,在验证理论模型合理...

Spatial Distribution Mode of Diffusion Pressure of Synchronous Grouting Filling for Quasi-Rectangular Shield Tunnel in Soft Soil Area

The filling and diffusion process of the grout in the tail clearance of quasi-rectangular shield tunnel was studied,in order to solve the problem of grout siltation that was likely to occur during the synchronous grouting in quasi-rectangular shield tunnel.According to the fluid mechanics principle,the longitudinal distribution mode of pressure ring of slurry under Bingham fluid condition was deduced,and the mechanical models and calculation methods of synchronous grouting circumferential filling and longitudinal diffusion for quasi-rectangular shield tunnel in soft soil area were obtained.Combined with the measured data in the tunnel project of the entry and exit section of Chenpodu Station of Ningbo rail transit Line 3,the rationality of the theoretical model was validated.On this basis,the distribution law and the influencing factors of grouting filling diffusion pressure along the longitudinal direction were analyzed.Results show that the synchronous grouting pressure of quasi-rectangular shield in soft soil area shows the distribution characteristics of upper small and lower large along the circumferential direction,and the local pressure of the irregular section has a certain fluctuation trend.The variation of grout pressure is mainly determined by the self-weight adding/reducing of the grout and the reduction of shear stress.The diffusion pressure along the longitudinal direction is only subjected to the shear stress that resists the flow and the pressure decreases gradually from the shield tail.The parameters which have great influence on the pressure distribution along the grout path mainly include the static shear stress of grout material,the thickness of ring cake and the width of shield tail void.There is a positive linear correlation between the static shear stress of grout material and the pressure loss along the grout path.The pressure loss along circumferential filling is the most sensitive to the thickness of the ring cake and the value range suitable for this model should be 0.02~0.03 m.The pressure loss along the longitudinal diffusion is the most sensitive to the width of shield tail void.The grouting pressure should be adjusted in real time according to the over/under excavation state of shield.