覆岩隔离注浆充填浆液无压阶段扩散规律实验研究

Experimental study on slurry diffusion law during the non-pressure stage in overburden isolated grouting

浆液流动规律对覆岩隔离注浆充填参数设计及技术效果具有重要影响。浆液流动受注浆压力控制,而实际的注浆压力由零压、增压等多阶段组成。研究表明,无压阶段内注采比最大可达10%,研究浆液在该阶段内的扩散规律有助于优化注浆初期的浆液参数与钻孔布置。本研究采用理论分析与实验研究方法进行覆岩隔离注浆充填浆液在无压注浆阶段的扩散规律研究,利用量纲分析方法建立浆液扩散距离的无量纲公式,设计可视化的注浆充填浆液扩散模拟系统,开展浆液扩散规律的实验研究,并对无量纲方程进行求解。实验系统由透明有机玻璃板构成的可视化模拟裂隙、恒速率注浆泵、搅拌机及监测等部分组成。利用该实验系统研究注浆流量、终孔距裂隙高度、浆液运动黏度等因素对粉煤灰浆液扩散距离与浆体形态的影响。实验结果表明:浆体扩散经历径向扩散和双向扩散两个阶段,并以双向扩散为主。其中,径向阶段呈以注浆孔为中心的圆形扩散,双向阶段呈两边对称的面状扩散。基于实验结果,求解浆液无压阶段的扩散距离公式,并对有效性进行验证。得出两个阶段浆体形态的简化描述模型,并推导不同扩散时间不同位置的浆体厚度计算公式,阐明无压注浆阶段的浆液扩散规律。基于研究结果对覆岩隔离注浆充填在无压阶段的注浆充填设计提出建议。

The law of slurry flow has significant influence on the parameter design and technical effect of isolated grouting. The slurry flow is controlled by the grouting pressure, and the actual grouting pressure consists of zero pressure, supercharging and other stages. The study shows that the injection-production ratio in the non-pressure stage can reach up to 10%, and the study of the slurry diffusion law in this stage is helpful to optimize the slurry parameters and borehole layout at the initial stage of grouting. For this reason, this paper adopted the theoretical analysis and experimental research methods to carry out the research on the diffusion law of overburden isolated grouting filling grout in the stage of no pressure grouting. The dimensionless formula of slurry diffusion distance was established by dimensional analysis. A visualized slurry diffusion simulation system was designed, and the experimental study of slurry diffusion law was carried out. The experimental system consists of transparent plexiglass plate, visual simulation of cracks, constant rate grouting pump, mixer and monitoring. The influence of grouting flow, end hole distance and crack height, slurry viscosity on slurry diffusion distance and slurry morphology was studied by using this system. The experimental results show that the diffusion of slurry has gone through two stages: radial diffusion and bidirectional diffusion. Among them, the radial stage presents a circular diffusion centered on the grouting hole, and the two-way stage presents a symmetrical planar diffusion on both sides. Based on the experimental results, the diffusion distance formula of the slurry in the non-pressure phase was solved, and the validity was verified. At the same time, the simplified description model of slurry morphology in two stages was obtained, and the calculation formulas of slurry thickness at different diffusion times and locations were derived to clarify the slurry diffusion law in the non-pressure grouting stage. Based on the research results, some suggestions were put forward for the grouting filling design of isolated overburden grouting filling in the no-pressure stage.