盾构同步注浆浆液固结及压力消散两相渗流理论模型研究

Research on Two-Phase Seepage Theoretical Model of Slurry Consolidation&Pressure Dissipation in Shield Synchronous Grouting

盾构隧道同步注浆过程中,由于浆液注入盾尾间隙后的压力高于地层静水压力,所以浆液会扩散到地层中发生渗流,并随着时间发生固结,浆液压力随之消散。在现有的分析模型中,浆液在地层中的渗流被看作单相流问题,忽略浆液与地下水在地层中渗流的差异性。在现有解析公式的基础上,将浆液在地层中的压力消散和渗流视为二维的两相流模型,分析浆液渗流以及驱替作用下地下水渗流引起的水头损失,并且考虑浆液黏度时变性的影响,推导盾构同步注浆浆液固结及压力消散的两相渗流理论模型。研究结果表明,浆液黏度时变性对浆液固结及消散的压力稳定值和体积损失率等计算结果有较大影响,浆液固结及压力消散理论模型中应根据固结时间和浆液扩散范围考虑浆-水两相渗流过程。

In the process of synchronous grouting of shield tunnel, because the pressureof slurry injected into the clearance of shieldtail is higher than that of formation hydrostaticpressure, the slurry will diffuse into the stratumand seepage occurs, and with time consolidation,the slurry pressure will dissipate. In the existinganalysis models, the seepage of slurry in theformation is considered as a single-phase flowproblem, ignoring the difference between slurryand groundwater seepage in the formation. Basedon the existing analytical formula, the pressuredissipation and seepage of slurry in the stratum areregarded as 2D two-phase flow model. The headloss caused by slurry seepage and groundwaterseepage under displacement is analyzed.Considering the influence of slurry viscosity timevarying,the two-phase seepage theoretical modelof slurry consolidation and pressure dissipationin shield synchronous grouting is deduced. Theresults show that the time-varying viscosity ofslurry has a great influence on the calculationresults of pressure stability value and volume lossrate of slurry consolidation and dissipation. Inthe theoretical model of slurry consolidation andpressure dissipation, the slurry water two-phaseseepage process should be considered accordingto the consolidation time and slurry diffusion range.