地下工程软弱砂土富水地层注浆加固机理研究

In underground engineering, the geological disasters such as collapse, water inrush and sand gushing have been easily caused by the weakly consolidated sandy soil and water-rich stratum. Due to the complexity and difference of weakly consolidated sandy soil, the grouting reinforcement mechanism of this stratum is a key scientific issue to be solved during its disaster control process. The theoretical analyses, laboratory experiments, numerical simulations, model tests and in-situ tests are combined to perform this research. The injectability of cement-based grout is investigated under various factors such as types of cement-based slurry, parameters of sand soil and grouting, etc., and the injectability criteria will be established. The critical conditions of filtration, the criterion of split and the related threshold range of key control factors are obtained. The spatial heterogeneous distribution characteristic of the permeation-filtration diffusion and the spreading path of split-compaction diffusion are revealed. The quantitative relationship between mechanical property of reinforcement body and grouting parameter is determined. The microscopic strengthening mechanism and mechanical failure characteristic are analyzed. The control mechanism of slurry-rock interface microstructure, mineral composition and crack propagation on mechanical property would be revealed. The theoretical mechanical model of failure will be established based on external disturbance force and complex geological environments such as overload of earth stress, water pressure, etc. Meanwhile, the related critical criterion for instability would be acquired, and then the failure mechanism would be revealed. The research results will be verified and improved through the related field tests. The above research results can supplement and enrich the grouting reinforcement theory of underground engineering effectively, and they are of great significance for grouting theory and disaster control practice of the weakly consolidated sandy soil and water-rich stratum.

地下工程软弱砂土富水地层极易诱发塌方、突水溃砂等地质灾害，由于砂土体自身复杂性与多样性，其注浆加固机理是灾害防控亟需解决的关键科学问题。本项目拟采用理论分析、室内试验、模型试验、数值模拟与现场试验等方法开展研究。研究多因素（水泥基浆液参数、砂土体参数、注浆参数）影响下砂土体水泥基浆液可注性，建立可注性判据。获取渗滤临界条件、起劈判据及相应主控因素阈值范围，揭示渗透-渗滤浆液空间非均匀分布特征及劈裂-压密扩散路径特征。获取注浆加固宏观力学性能定量强化机制与微观加固作用机制，分析加固体破坏力学特征，揭示界面微观结构及裂纹扩展对加固体力学特性的主导机制。建立工程扰动下复杂地质环境（地应力、水压力超载等）地层失稳破坏力学模型，获取工程加固地层失稳临界条件，揭示失稳破坏机制。通过现场试验进行成果验证和完善。以上研究成果补充与完善了地下工程注浆加固理论，对类似地层灾害控制具有重要理论与实践意义。

地下工程软弱砂土富水地层极易诱发塌方、突水溃砂等地质灾害，由于砂土体自身复杂性与多样性，其注浆加固机理是灾害防控亟需解决的关键科学问题。本项目采用了理论分析、室内试验、模型试验、数值模拟与现场试验等方法开展研究。研究了多因素（水泥基浆液参数、砂土体参数、注浆参数）影响下砂土体水泥基浆液可注性，建立了可注性判据。获取了渗滤临界条件、起劈判据及相应主控因素阈值范围，揭示了渗透-渗滤浆液空间非均匀分布特征及劈裂-压密扩散路径特征。获取了注浆加固宏观力学性能定量强化机制与微观加固作用机制，分析了加固体破坏力学特征，揭示了界面微观结构及裂纹扩展对加固体力学特性的主导机制，为灾害注浆防控理论奠定了理论基础。研发了新型高效注浆材料EMCG及其配套工业制备技术与生产工艺。基于“超细分级-固废互补协同-火山灰效应”原理，研发了新型高效注浆材料，具有可注性高、抗渗抗蚀、微膨胀、高强高耐久、泵送稳定、凝胶时间可控等优点；研发了配套工业化生产工艺体系与检验标准，提高了粉磨及均化效率，为新材料工业生产及大规模应用提供了技术保障。建立了工程扰动下复杂地质环境（地应力、水压力超载等）地层失稳破坏力学模型，获取了工程加固地层失稳临界条件，揭示了失稳破坏机制。通过现场试验验证和完善了研究成果。以上研究成果补充与完善了地下工程注浆加固理论，对类似地层灾害控制具有重要理论与实践意义。攻克了地下工程富水砂土软弱地层灾害主动防控核心成套技术体系难题。提出了注浆加固效果定量估算方法；建立了多序注浆扩散模型，提出了浆脉尺寸的判定方法和标准；研发了预加地层水平应力、关建孔优选等注浆加固技术；提出了关键注浆参数注浆全过程控制方法，实现了注浆压力、浆脉尺寸、加固体参数和注浆进度控制；建立了富水砂土软弱地层注浆工程设计方法。