裂隙岩体水平孔注浆浆液扩散规律研究

Study on diffusion law of grouting slurry in horizontal hole in fractured rock mass

华北型煤田深部开采过程中受底板水害威胁愈发严重,水平孔注浆技术是治理此类水害的主要手段,其中浆液扩散规律的研究对注浆工程设计与施工具有重要意义。现有研究主要针对垂直孔注浆水平裂隙中浆液的扩散问题,当工程中采用水平孔注浆时浆液的扩散规律异于垂直孔。为此开展裂隙岩体水平孔注浆浆液扩散规律研究,将裂隙岩体中的孔裂隙系统等效为开度相同的裂隙,构建了等效裂隙岩体模型。选取等效单裂隙建立了水平孔注浆浆液扩散力学模型,推导了任意倾角的等效单裂隙在考虑浆液自重时浆液扩散区内的压力时空分布方程,进而得到注浆压力与注浆时间及扩散距离的理论关系式。结果表明:采用COMSOL建立水平孔注浆垂直裂隙三维数值计算模型,分别对考虑重力和未考虑重力的2种工况进行计算分析,未考虑重力时浆液的扩散形态呈轴对称圆形扩散,考虑重力时浆液优先沿着重力方向进行扩散。在重力的影响下,浆液扩散过程中地下水对浆液分散与搬运作用更为强烈。重力对水平孔注浆浆液扩散形态、扩散距离及注浆终压影响较大,水平孔注浆工程中不能忽视重力对浆液扩散规律的影响。通过对比理论分析与数值计算结果,两者得到的注浆压力与注浆时间、注浆终压与扩散距离的变化趋势基本一致,理论与数值计算结果的误差控制在10%左右,进一步验证了所建立的水平孔注浆浆液扩散力学模型的正确性。研究成果能够为水平孔注浆工程中注浆终压、注浆方式及扩散距离的设计提供科学依据。

In the deep mining process of North China type coalfield,the threat of floor water damage is more and more serious.The use of horizontal hole grouting technology is the principal means to control this kind of water damage,and the study of the slurry diffusion law is of great significance in the design and construction of grouting engineering.The existing research mainly aims at the problem of slurry diffusion in horizontal fractures with vertical hole grouting.When horizontal hole grouting is employed in engineering,the diffusion law of slurry is different from that of a vertical hole.Therefore,the diffusion law of grouting slurry in horizontal holes of fractured rock mass was studied,and the pore and fracture system in a fractured rock mass was equivalent to the fracture with the same opening,and the equivalent fractured rock mass model was constructed.The mechanical model of grout diffusion in the horizontal hole was established by selecting the equivalent single crack,and the pressure time-space distribution equation of the equivalent single crack with any dip angle in the grout diffusion area was derived when considering the grout self weight.Then the theoretical relationship between grouting pressure and grouting time and diffusion distance was obtained.COMSOL was used to establish a three-dimensional numerical calculation model for the vertical fracture of the horizontal hole grouting,and the calculation and analysis were carried out for two working conditions considering gravity and without gravity.When gravity was not considered,slurry diffusion morphology was axisymmetric circular diffusion,and when gravity was considered,the slurry was preferentially diffused along the direction of gravity.Under the influence of gravity,the effect of groundwater on the dispersion and transportation of slurry was stronger in the process of slurry diffusion.Gravity has a great influence on the diffusion pattern,diffusion distance and final grouting pressure of a horizontal hole grouting.By comparing the theoretical analysis and numerical results of both the grouting pressure and grouting time,the variation trends of grouting pressure and grouting time,grouting final pressure and diffusion distance obtained by the two are basically consistent,and the error between the theoretical and numerical calculation results is controlled at about 10%,which further verifies the established level hole grouting the correctness of the grout diffusion model.The research results can provide scientific basis for the design of grouting final pressure,grouting method and diffusion distance in horizontal hole grouting engineering.