溶蚀孔隙型白云岩浆-水径向扩散模型及工程应用EI北大核心CSCD

为解决我国西南地区巨厚溶蚀孔隙型白云岩含水层井筒防治水难题,基于达西定律建立孔隙型地层浆-水两相流径向扩散模型,研究了孔隙型地层注浆过程中浆液扩散规律,推导了浆相饱和度演化方程,并得到了浆相饱和度沿径向距离计算公式。浆相饱和度沿径向可分为浆相区、浆水混相区和水区,浆水混相区和水区分界面为浆相前沿。浆相饱和度面随浆液注入而不断向前推进,满足堵水要求的浆液有效扩散距离明显小于浆相前沿扩散距离。同时,采用现场注浆试验结合数值模拟,对老虎洞磷矿回风井溶蚀孔隙型白云岩含水层地面预注浆技术参数进行研究,分析了钻孔布置最优孔间距和浆液有效扩散距离,并据此提出回风井地面预注浆方案。回风井后续注浆完成后,通过压水试验得到注浆堵水效率为98.04%。该研究成果可为类似孔隙型地层注浆堵水工程提供技术参考。

Model of grout-water two-phase radial diffusion in dissolved porous dolomite and its engineering application

To solve the problems of preventing and controlling water for vertical shaft in ultra thick dissolved porous dolomite aquifer in southwest China, a grout-water two-phase radial diffusion model is proposed to study the diffusion laws of the grout in the porous stratum based on Darcy's law. The fractional-flow equation of grout is derived and the advancing distance of the grout saturation along the radial direction is obtained. According to the distribution of the grout saturation along the radial distance, the diffusion area could be divided into grout area, grout-water mixing area and water area. The shock saturation front is the interface between the grout-water mixing area and the water area. The grout saturation face moves forward with the grout injection, and the effective diffusion distance of the grout to meet the requirement of water prevention is significantly smaller than the diffusion distance of the shock front. Moreover, the technical parameters of surface pre-grouting for sealing the dissolved porous dolomite aquifer in ventilation shaft of the Laohudong phosphate mine are studied by field test combining with numerical simulation. The optimal borehole spacing and effective diffusion distance are obtained. Consequently, the engineering design of surface pre-grouting for the ventilation shaft is proposed based on these technical parameters. Finally, after the completion of grouting, the sealing efficiency of the grouting for the ventilation shaft could reach up to 98.04% obtained from the water pressure test. The research results of the present paper could provide technical reference for water sealing by grouting for similar porous aquifer.