考虑渗滤效应的超细水泥注浆机理分析

Analysis on the mechanism of ultrafine cement grouting considering the percolationeffect

摘要

注浆能显著提升粉细砂层的抗渗和承载性能,目前在地铁隧道等工程建设中得到了广泛应用。基于黏性流体运动理论,考虑浆液扩散Darcy定律、线性滤过原理、渗流连续性条件及压力降方程,建立渗滤效应下超细水泥浆液扩散的理论模型,探索多孔介质中浆液锋面速度、压力的变化机理,并结合厦门某工程项目建设进行实测验证。研究结果表明:不考虑渗滤作用的恒速注浆时,其锋面速度为考虑渗滤作用的3.9~5.8倍,而不考虑渗滤作用的恒压注浆时,其锋面速度则为考虑渗滤作用的1.6~1.9倍;某固定时刻浆液压力降和锋面压力沿程减小,随渗滤作用的加剧水泥颗粒逐渐在孔隙通道上滞留沉积,浆液锋面压力逐渐回升。工程实测显示,理论计算值与实际值存在14%~19%的误差,表明所建立的三维锋面扩散模型具有较高的适用性,可为土木、水利等注浆工程提供借鉴和指导。

Abstract

Grouting can significantly improve the impermeability and bearing capacity of silty fine sand layers, and has thus been widely used in engineering construction of subway tunnels and other projects. Based on the theory of viscous fluid motion, and incorporating Darcy's law of slurry diffusion, the linear filtration principle, seepage continuity conditions and the pressure drop equation, a theoretical model for the diffusion of ultra-fine cement slurry under the percolation effect was established. This model investigates the change mechanism of slurry front velocity and pressure in porous media, and is validated through field measurements from a construction project in Xiamen. The results indicate that under constant-rate grouting, the front velocity without considering percolation effect is 3.9 to 5.8 times that when percolation is considered. Under constant pressure grouting, the front velocity without considering percolation effect is 1.6 to 1.9 times that with percolation considered. At a given time, both the slurry pressure drop and the front pressure decrease along the flow path; as the percolation intensifies, cement particles gradually accumulate in the pore channels, and the slurry front pressure gradually rises. Engineering measurements show that the discrepancy between theoretical calculations and actual values ranges from 14% to 19%, demonstrating that the proposed three-dimensional front diffusion model possesses high applicability and can serve as a reference and guide for grouting engineering in civil and hydraulic engineering fields.

关键词

地铁工程 / 多孔介质 / 渗滤效应 / 扩散机理 / 超细水泥

Key words

subway engineering / porous media / percolation effect / diffusion mechanism / ultrafine cement

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基金资助

河南省自然科学基金项目(252300420053)