砂卵石地层盾构隧道同步注浆流固耦合效应宏微观机理研究

Synchronized grouting is one of the important measures to fill the tail-void between tunnel lining and surrounding ground. In addition, the synchronized grouting process can result in significant disturbance on surrounding soils. Since the complex interaction between grout and surrounding ground, the mechanism of grout filling, compaction, seepage, and consolidation has not been sufficiently investigated. The fluid-solid interaction, as well as the evolution of material micro-properties, has not been sufficiently considered in existing researches on the effect of synchronized grouting. In this study, experiment-based CFD-DEM simulations will be employed for the micro-scale research on the fluid-solid interaction between strata and grout during grout seepage and consolidation; based on the micro-scale investigation, the macro-scale research on the disturbance-failure process of the strata during grout filling and compaction will be carried out by 1g model test and CFD-FEM simulations; on the basis of micro-scale and macro-scale studies and practical engineering, the influence of grouting variables on the disturbance of surrounding strata will be investigated by conducting elaborate full-scale numerical simulations on the synchronized grouting process. The outcomes will enhance current knowledge of the mechanism of fluid-solid interaction during synchronized grouting, and provide the control of synchronized grouting induced disturbance on surrounding soils with the theoretical fundamentals and technical support.

同步注浆是填充盾尾孔隙的关键环节，也是盾构施工中地层扰动的主要因素之一。由于浆液-土体复杂的相互耦合作用，同步注浆的填充、压密、渗透和固结机理尚未明确。现有同步注浆作用机理的研究大多没有充分考虑该过程的流固耦合效应以及微观尺度的材料特性演化。本课题将通过基于室内试验的CFD-DEM耦合数值模拟，从微观尺度研究浆液渗透和固结过程中地层与浆液之间的流固耦合效应；在此基础上，采用1g相似模型试验和CFD-FEM方法从宏观尺度研究浆液填充和压密作用下砂卵石地层的扰动-破坏机理及其演化规律；基于宏、微观尺度的研究，以实际工程为背景，对同步注浆施工进行精细化的足尺数值模拟，揭示不同注浆参数对地层扰动的影响。研究成果可丰富和完善当前对同步注浆流固耦合机理的认识，并为砂卵石地层中同步注浆施工的地层扰动控制提供理论基础和技术支撑。

盾构法施工因具有施工效率高、环境影响小、地层适应性好等优点已被广泛运用，但其施工过程带来的地层扰动仍不容忽视，如坍塌和地表隆沉超限问题，其中大多数事故是由不恰当的同步注浆施工造成的。本项目通过宏微观数值模拟的方法对地层中同步注浆浆液的支护作用进行微观尺度研究，研究不同地层盾尾同步注浆浆液和地层的微观流固耦合相互作用；在此基础上，通过开展基于1g相似模型试验平台的盾尾同步注浆模型试验，采用宏微观数值模拟的方法模拟盾尾同步注浆的填充、压密以及地层扰动–破坏的演化过程，研究砂卵石地层同步注浆地层扰动-破坏演化规律；基于宏观尺度研究所获取的注浆压力分布、注浆率以及地层扰动程度之间的关系，采用FEM方法对砂卵石地层中盾构同步注浆的施工进行足尺精细化数值模拟，研究考虑宏-微观流固耦合效应的同步注浆扰动控制方法。本项目结合理论分析、试验及数值模拟试验，揭示了同步注浆浆液填充、扩散和支护的微观流固耦合机理，深入研究了同步注浆影响下地层的扰动–破坏模式及其发展规律，对于同步注浆参数的选择和地层扰动的施工控制具有重要的意义。