强采动大巷破碎煤柱水泥基浆液注浆渗透扩散规律研究

Study on Infiltration and Diffusion Law of Cement-based Grout Grouting of Broken Coal Pillar in Strong Mining Roadway

以山西万家庄煤业强采动运输大巷破碎煤柱注浆修复加固为工程背景,首先开展水泥基浆液的流变性能实验,得到水泥基浆液流变参数;然后基于水泥浆液流变性实验室测试结果及渗流理论,利用COMSOL软件建立破碎煤柱水泥基浆液注浆渗透扩散数值计算模型,研究不同注浆参数(浆液黏度、裂隙开度、注浆压力等)条件下破碎煤柱中水泥基浆液渗透扩散空间分布特征及演化规律;最后,通过现场注浆量监测及钻孔全景数字成像探测技术,分析水泥基浆液渗透扩散效果。结果表明:当水灰比小于0.7时水泥基浆液黏度随水灰比增加急速下降,大于0.7时水泥基浆液黏度减小速率明显降低;水泥浆液扩散距离随时间非线性增长,呈现为幂函数关系;在破碎煤体裂隙中渗透扩散距离随水灰比、裂隙开度、注浆压力的增大而增大,根据万家庄煤业实际情况确定水灰比选择0.8,注浆压力选择3 MPa。现场监测结果表明,煤柱中的裂隙及破碎带中均可观察到大量水泥浆液,浆液渗透扩散效果较好,围岩完整性及自承能力显著提高,万家庄煤业运输大巷围岩稳定性得到良好控制。

The restoration and reinforcement of broken coal pillar by grouting in strong mining transportation roadway of Shanxi Wanjiazhuang coal industry was taken as the engineering background.Firstly,rheological properties of cement-based grout were tested and rheological parameters of cement-based grout were obtained.Then,based on the rheological test results of cement grout in laboratory and seepage theory,a numerical calculation model of permeability and diffusion of cement-based grout in broken coal pillar was established using COMSOL software.The spatial distribution and evolution of cement-based grout in broken coal pillar under different grouting parameters(slurry viscosity,crack opening,grouting pressure,etc.)were studied.Finally,the seepage and diffusion effect of cement-based grout was analyzed by in-situ grouting quantity monitoring and borehole panoramic digital imaging detection technology.The results show that when the water-cement ratio is less than 0.7,the viscosity of cement-based slurry decreases rapidly with the increase of the water-cement ratio.When the water-cement ratio is greater than 0.7,the viscosity of cement-based slurry decreases significantly.The diffusion distance of cement grout increases nonlinearly with time and presents a power function relation.The permeability diffusion distance increases with the increase of water-cement ratio,crack opening and grouting pressure.According to the actual situation of Wanjiazhuang coal industry,it is suggested to choose 0.8 water-cement ratio and 3 MPa grouting pressure.The site monitoring results show that a large amount of cement grout can be observed in the cracks and broken zone of coal pillar.The infiltration and diffusion effect of grout is remarkable.The integrity and self-bearing capacity of surrounding rock were significantly improved.The stability of surrounding rock of transportation roadway of Wanjiazhuang coal is well controlled.