超大直径盾构隧道同步双液注浆原位试验研究

为探明水泥-水玻璃双液浆在超大直径盾构隧道工程中的浆液特性、扩散形态及注浆填充效果，在北京东六环京哈高速—潞苑北大街区段盾构隧道工程负环段进行同步双液注浆原位试验，通过在负环管片上安装钢套筒的方式形成盾尾注浆间隙，并采用土压力和孔隙水压力传感器检测同步双液注浆过程中盾尾间隙内压力的分布及变化情况，探明双液浆的胶凝特性及初步扩散形态。注浆完成后，通过现场取样和三维激光扫描的方式揭示双液浆的物理力学性能和注浆填充效果。研究结果表明： 1）在同步双液注浆过程中，双液浆浆液压力整体呈“单峰”式曲线变化，即注浆开始后传感器量值随浆液注入快速增加，在注浆停止后传感器量值迅速下降，然后缓慢下降，最后稳定至一定量值； 2）由于原位试验过程中室外温度变化大、湿度低，并且存在混合不均及双液浆产物不稳定的问题，现场取样测得的抗压强度略低于室内试验所测得的抗压强度； 3）由三维激光扫描结果可知，适当调整注浆参数后双液浆能够很好地填充盾尾间隙，注浆圈无明显缺陷。

In Situ Experiment on Synchronous Double Component Groutingin Super Large Diameter Shield Tunnel

To investigate the characteristics, diffusion pattern, and grouting filling effect of synchronous cement sodium silicate grout in super large diameter shield tunnels, an in situ experiment of synchronous double component grouting is performed in the negative ring section of the shield tunnel project of the Beijing Harbin expressway Luyuan north street section on Beijing East Sixth Ring road. The shield tail grouting gap is formed by installing a steel sleeve on the section, and earth and pore water pressure sensors are employed to monitor the pressure distribution and variation in the shield tail gap, and the gelling characteristics and preliminary diffusion pattern of the double component grout are obtained. After the completion of synchronous grouting, the mechanical properties and filling effect of the double component grout are analyzed and tested by on site sampling and three dimensional laser scanning. The test results reveal the following: (1) The sensor as a whole changes in a "single peak" curve, i.e., when the grouting starts, the sensor value increases sharply, the sensor value drops suddenly after the grouting stops, and finally, the sensor value drops slowly and stabilizes at a certain value. (2) Owing to the large temperature change and low humidity outside, as well as uneven mixing and unstable product of the double component grout, the compressive strength obtained by sampling at the test site is slightly lower than that measured in an indoor test. (3) The three dimensional laser scanning results show that the synchronous double component grout can fill the shield tail gap well after appropriate parameter improvements and that the grouting circle has no obvious defects.