盾构隧道壁后注浆地层及浆液颗粒特性分析

Analysis of the Particle Characteristic of the Surrounding Rockand Grout as Backfill Grouting of Shield Tunnel

壁后注浆是盾构隧道施工的关键步骤,针对浆液扩散的复杂过程,基于浆液和地层的颗粒特征,分析浆液在地层中的扩散机理。地层土体可分为粗粒土和细粒土两类,粗粒土地层的孔隙结构受地层颗粒粒径、粒径级配、孔隙率等的影响;细粒土地层中,由于细颗粒与地下水的相互影响,地层的渗透性较小,影响因素复杂。浆液的流变性为水泥浆液的宏观性质,与水泥颗粒的含量、浆液拌和时间等有关;浆液扩散过程中,由于浆液流变性的影响,浆液内部压力随扩散距离的增加而逐渐减小。最后根据室内渗透试验,对颗粒材料在地层中的扩散形式进行了总结,根据颗粒在地层中的沉积特征,将低压注浆浆液扩散形式分为筛滤、渗滤、压滤、渗透四种,并根据浆液扩散过程,提出四种典型浆液扩散类型。

The backfill grouting is an important step in the construction of shield tunnel.The diffusion mechanism of grout is analyzed based on the particle characteristics of the surrounding rock and grout.The soil can be divided into coarse grain soil and fine grain soil.The pore structure of coarse grain soil layer is affected by the particle size,particle size distribution,pore rate,etc.Due to the interaction between fine particles and groundwater,the permeability of fine grain soil stratum is smaller and affected by more complex factors.The rheological property of gout is the macro-nature of cement grout,which is related to the content of cement particles,grout mixing time.In the process of grout diffusion,due to the effect of grout rheological property,the internal pressure of slurry gradually decreases with the increase of diffusion distance.Finally,based on the indoor osmosis test,the diffusion form of particle material in the grout layer is summarized,according to the sedimentary characteristics of the grout particles in the surrounding rock,the low pressure grout diffusion form is divided into four kinds,i.e.sieve,leaching,pressure filtering,penetration,and four typical grout diffusion types are proposed according to the process of grout diffusion.