考虑时变性影响的盾构壁后注浆浆液固结及消散机制研究

A study on grout consolidation and dissipation mechanism during shield backfilled grouting with considering time effect

在盾构管片壁后注浆时,由于浆液渗透压的存在,浆液会向外渗透,浆体本身逐渐固结,作用在管片上的注浆压力逐渐消散。考虑到浆液往周边地层渗透过程中由于黏度的变化会引起地层渗透系数的变化,推导了基于浆液黏度时变性的浆体固结变形方程和浆液压力消散方程,分析了浆液固结、消散及浆液压力沿管片外壁分布规律,为精细化分析施工阶段管片受力提供了计算依据。计算结果表明:浆液从注浆口喷出后,浆液黏性的增大使浆液流动性减小,注浆压力消散幅度减小,浆液消散持续时间变短。浆液配比与围岩渗透系数变化对注浆压力消散幅度及消散持续时间存在一定影响。现场实测结果与理论计算结果较为一致。在进行壁后注浆时,应充分考虑时变作用下浆液消散作用的影响。

The water in grout will permeate toward surrounding rock due to the osmotic pressure, so that the grout itself will consolidate gradually during shield backfilled grouting; and the grouting pressure will dissipates slowly. The variation of grout viscosity will lead to a change in the permeability of soil layers during the grouting process. Based on this fact, the grout consolidation and pressure dissipation equations have been deduced; and the distribution regularities of grouting pressure acting on segments have been analyzed, which provide a guideline for fine analysis of segment mechanics during construction. The results show that： the increase of grout viscosity will result in decreases in the grout liquidity, the extent of grouting pressure dissipation and duration time of grout dissipation. The variation of grout mixing proportion and permeability coefficient of surrounding rock can also influence the extent of grouting pressure dissipation and duration time of grout dissipation.. The calculated results are consistent with the field measured results. It is suggested that the grout dissipation effect due to time-varying should be taken into account in backfilled grouting.