隧道砂卵石围岩超前小导管注浆参数优化研究

隧道砂卵石围岩具有结构松散、级配分布不均匀,透水性强的特点,在进行注浆加固地层时,应合理确定注浆参数。以甘肃省渭武高速白鹤桥隧道为工程依托,结合砂卵石地层的特点,针对单水泥浆浆液易析水、水泥颗粒易沉降、凝结时间难控制、结石体易收缩、注浆压力及小导管间距难确定等问题,通过室内注浆材料试验、改性普通硅酸盐水泥性能试验及注浆模型试验对注浆加固参数进行优化设计,并提出相应的注浆控制标准。研究结果表明,最优注浆参数为:水灰比为1∶1;水玻璃波美度为38Be′,用量为3%;悬浮剂用量为1.4%;注浆压力取0.2 MPa;注浆小导管间距取30 cm。

Study on Optimization of Grouting Parameters of Advanced Ducts in Sand and Gravel Surrounding Rock of Tunnels

The sand and gravel surrounding rock of the tunnel is characterized by loose structure, uneven gradation and strong permeability. Grouting parameters should be determined reasonably for grouting and strengthening the stratum. Based on the project of Baiheqiao tunnel of Weiwu highway in Gansu province, combined with the characteristics of sandy pebble formation, and in view of such challenges as the easy drainage of the single cement slurry, the cement particle sedimentation, the difficult to control the setting time, the easy contract of the stone body, the grouting pressure and small conduit spacing, indoor grouting material test, modified ordinary Portland cement grouting materials test and grouting model test are conducted to optimize the grouting reinforcement parameters, and corresponding grouting control standards are put forward. The results show that the optimal grouting parameters are as the followings: water-cement ratio is 1∶1; water glass baume degree is 38° of 3% dosage; dosage of the suspending agent is 1.4%; grouting pressure is 0.2 MPa and spacing of the grouting catheter is 30 cm.