岩质地层盾构隧道水泥-水玻璃双液同步注浆耐久性机理研究

During the construction process of shield tunnels in rock mass, various problems resulted by synchronous backfill grouting have been clearer and more obvious in the subway projects in Shenzhen, Guangzhou, Fuzhou and some other places as well as in the construction of many underwater shield tunnels. They include cutterhead deadlocking, segments floating and crack, surface subsidence, etc. Because of its rapid consolidation properties, cement - sodium silicate grouting can effectively solve the above problems, but meanwhile, its durability cannot be guaranteed, thus so far it has hardly been adopted in synchronous backfill grouting of shield tunnels..This project, a systematic research on the durability of cement - sodium silicate grout in rock mass of shield tunnels, has explored the reaction mechanism, physical and mechanical properties of cement - sodium silicate grouting as well as the meso-structure of its reaction product and its mechanism of deterioration, found the method of mechanical property reduction of cement - sodium silicate grout and put forward a mechanical performance improvement plan of the grout. This project has also studied the durability of the grouting circle and the law of its influence on the long-term security to the segment structure under the interaction of the segment structure, the grouting circle and rocks, taken the performance deterioration of cement - sodium silicate grouting circle into account and made the shield tunnel segment designing. The research results will offer theoretical bases and practical approaches to the adoption of cement - sodium silicate synchronous backfill grouting in shield tunnels of rock mass. At the same time, it will also provide some reference for the construction of shield tunnels in upper-soft lower-hard ground.

岩质地层盾构隧道施工过程中因同步注浆导致的刀盘卡死、管片上浮、管片裂损和地表沉陷等诸多问题已在深圳、广州、福州等地铁工程及大量水下盾构隧道的建设过程中凸显，水泥-水玻璃双液浆因其快速固结特性能够有效解决上述问题，但因其耐久性难以保证，至今在盾构隧道同步注浆中鲜有应用。本项目通过对岩质地层盾构隧道水泥-水玻璃双液同步注浆耐久性机理开展系统研究，探明水泥-水玻璃双液浆的反应机理、物理力学特性、反应产物的细观结构及其劣化机理，建立水泥-水玻璃双液浆力学性能折减方法，提出双液浆力学性能改善方案；探明管片结构、注浆圈与岩体相互作用下注浆圈的耐久性及其对管片结构长期安全的影响规律，建立考虑水泥-水玻璃双液同步注浆圈性能劣化的盾构隧道管片设计方法。项目研究成果将为岩质地层盾构隧道采用水泥-水玻璃双液同步注浆工艺提供理论依据和实用方法，同时可为上软下硬地层盾构隧道的建设提供参考。

为克服盾构隧道掘进施工时采用单液浆注浆所带来的管片上浮严重、注浆跑浆、管片局部受力不均匀易破裂等问题，开展了盾构隧道壁后双液浆注浆技术的研究，采用理论分析、室内实验、数值模拟等手段研究双浆液的基本性能及其长期可靠性，提出适用于深港隧道内地段盾构隧道的管片壁后同步注浆的双浆液适用配合比方案，主要取得成果如下：.1）对双液浆组分之间的反应比例、反应规律进行了室内试验，结果表明双液浆结石体抗压强度随龄期的增长而增大，界定了双液浆中水玻璃掺量范围的合理范围，得出了结石体的抗压强度和弹性模量的变化规律。.2）通过对双液浆结石体的细观研究，得出水泥-水玻璃双液浆注浆体的劣化机理，识别了水泥-水玻璃反应的产物，并且通过统计分析，归纳总结了水泥-水玻璃反应产物的三种形态及其占比，结合极限分析方法，得出不同配比双液浆注浆体裂化后的折减系数。. 3）通过对不同地层条件下使用双液浆后管片的内力和变形进行数值模拟分析，得出管片的受力和变形规律。考虑了注浆层的劣化效应，通过对注浆层的弹性模量进行折减后，计算分析了不同地层条件下管片衬砌结构的力学性能变化特点，论证了极端不利工况下管片衬砌结构的长期安全性问题，结果表明双液浆浆体裂化后仍能够满足其自身可靠性要求。.项目研究成果对岩质地层水泥-水玻璃双液浆同步注浆配比提供理论依据和实用参考，以期指导实际工程施工作业。