砂层渗透注浆加固效果模型试验研究
Simulation test for permeation grouting reinforcement effect of sand layer
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摘要: 渗透注浆是煤矿井筒穿越砂层段防渗加固的重要手段之一,为研究砂层渗透注浆加固效果,研发了一套砂层渗透注浆模型试验装置,该装置具备多个试样同时注浆、不拆模测试注浆试样渗透系数等功能;以抗压强度、变形模量、渗透系数作为评价砂层渗透注浆加固效果的性能指标,选取砂层粒径级配、黏性土含量、浆液水灰比、注浆压力4个因素作为渗透注浆效果的影响因素,开展了砂层渗透注浆加固效果正交试验,获得了影响砂层渗透注浆效果的主控因素以及不同条件下砂层注浆加固体的变形破坏特征。研究结果表明:砂层经渗透注浆加固后,3 d抗压强度可达到0. 5~8. 5 MPa,3 d变形模量可达到35~750 MPa,1 d渗透系数可达到10-6~10-7cm/s数量级;浆液水灰比是控制砂层注浆加固效果的主控因素,随着浆液水灰比的增加,砂层注浆加固体抗压强度、变形模量及抗渗性能均显著降低;砂层注浆加固体破坏模式受浆液水灰比影响显著,低水灰比(W/C=0. 8左右)对应整体破坏模式,高水灰比时(W/C=1. 6左右)水泥浆液析水效应对加固体破坏过程产生影响,使其呈现出局部破坏模式,在砂层渗透注浆加固工程中应尽可能选用低水灰比的水泥浆液。Abstract: Permeation grouting method is effectively used in sand layer which usually exposed by mine shaft to shutoff water and reinforce strata. To study the permeation grouting reinforcement effect of sand layer,a simulation test device was developed for testing permeation grouting,which can grout several samples simultaneously and measure permeabil- ity coefficient without mold stripping. Compressive strength, deformation modulus and permeability coefficient were used as the evaluation index of grouting reinforcement effect. With four influencing factors,including sand layer grada- tion,cohesive soil content,water cement ratio and grouting pressure,the or-thogonal test of permeation grouting rein- forcement effect was implemented. Ultimately,the main controlling factor of grouting reinforcement effect was obtained,and the deformation and failure characteristics of grouted sand samples under different conditions were revealed. Re- sults show that:sand layer obtains better performances after grouting,three day compressive strength reaches 0. 5-8. 5 MPa,three day deformation modulus reaches 35 -750 MPa,and one day permeability coefficient reaches 10-6 ~ 10-7 cm / s. Water cement ratio of slurry is the main con-trolling factor of permeation grouting reinforcement effect of sand layer. When water cement ratio grows,the compressive strength,deformation modulus and anti-permeability of sand layer will decrease significantly. De-formation and failure mode of grouted sand is affected by water cement ratio markedly. Low water cement ratio (W / C = 0. 8) will lead to global failure mode. High water cement ratio (W / C = 1. 6) will result in local deformation and failure mode,and the bleeding water effect of cement will affect the failure process of grouted sand. First selection of cement grout with low water cement ratio is suggested in the permeation grouting pro- jects of sand layer.