盾构隧道壁后注浆浆液毛细管渗透扩散模型

为探讨盾尾注浆扩散半径及管片所受注浆压力的计算方法,将浆液的扩散过程简化为其在土体中大量孔径不均匀的毛细管中的渗流运动,建立了浆液渗透扩散力学模型.基于柱面扩散理论,假定浆液为宾汉姆流体,引入等效孔隙率替代土体初始孔隙率,通过模拟浆液在单个毛细管中的渗透过程,得到了考虑浆液时效性的浆液扩散半径和管片所受浆液总压力的计算式.结合具体实例,讨论了浆液扩散半径、注浆对管片产生的压力与注浆压力和注浆时间的关系.分析结果表明:其他注浆参数相同时,在不同注浆压力和不同注浆时间条件下,浆液对管片产生的压力的增长速率均大于浆液扩散半径的增长速率;当盾尾建筑间隙影响厚度和土体等效孔隙率不变时,浆液流动锋面上毛细管总面积与浆液扩散半径成正比. 

Capillary Penetration Diffusion Model for Backfill Grouting of Shield Tunnel

In order to discuss the calculating method of diffusion radius and pressure on segments of backfill grouting, a mechanical model for penetration diffusion in surrounding soils was set up by simplifying grouting penetration as transfusion in soil capillary tubes with uneven bore diameters. Based on the cylinder diffusion theory and the assumption that grout is as Bingham fluid, under the premise of bring the equivalent porosity to replace the soil porosity, the calculation formula of the diffusion radius and the pressure on segments of backfill grouting were obtained through simulating the penetration process of grout in single capillary tube. Then, the relations between grouting pressure, time, and the diffusion radius, pressure on segments were discussed through a detail example. The result shows that the increase rate of the pressure on segments is bigger than that of the grouts diffusion radius under different grouting time and pressure, and the total capillary area on the grouts flowing frontal surface is in proportion to diffusion radius when keep the influence depth of tail gap and the soil equivalent porosity unchanged.