倾斜裂隙水平孔注浆浆液扩散规律

Law of grout diffusion of horizontal hole grouting in inclined crack

华北型煤田下组煤资源受奥陶系中统厚层灰岩或太原组薄层灰岩等承压含水层突水威胁严重,现阶段利用水平定向钻对含水层进行超前区域注浆改造是消除底板突水威胁、解放煤炭资源的重要手段。但由于底板岩溶裂隙含水层水平注浆孔浆液扩散规律不清,注浆设计和工程实践中的关键注浆参数确定缺少理论依据,无法有效把控注浆过程、保证注浆效果,因此综合采用室内试验、理论推导、数值分析、对比验证和数值模拟等手段研究构建了倾斜裂隙水平注浆孔牛顿流体和黏时变性流体浆液扩散模型,通过模型试验和数值模拟计算进行了对比验证,计算分析了不同因素下倾斜裂隙浆液扩散迹线和扩散距离变化规律。研究结果:理论计算得到的浆液扩散形态和倾角的影响特征与倾斜裂隙浆液扩散物理模型试验结果和数值模拟计算结果具有一致性;岩溶含水层单裂隙中不同注浆压力、裂隙倾角(不包括0°)、裂隙开度和浆液水灰比下中浆液扩散形态为沿中心垂线对称的近似椭圆形态,上方裂隙中部迹线呈现微凹特征分布,浆液扩散距离最大值和最小值分别出现在方位角180°和0°位置。下方裂隙浆液扩散迹线范围的增加幅度大于上方裂隙;浆液扩散迹线范围在下方裂隙和上方裂隙中随裂隙倾角增加分别增大和减小;相同条件下,水平注浆孔上方裂隙中的浆液扩散距离大于下方裂隙中的,且在宽张裂隙尺度下差距呈现倍数增加特征。

Coal resources in the lower formation of the North China type coalfield are seriously threatened by water inrush from confined aquifers such as thick limestone of middle Ordovician system and thin limestone of Taiyuan Formation.At present,it is an important means to eliminate the threat of floor water inrush and release coal resources by carrying out advanced regional grouting transformation of aquifers using horizontal directional drilling.However,due to the unclear diffusion law of grout in horizontal grouting hole of karst fissure aquifer on the floor and the lack of theoretical basis for determining key grouting parameters in grouting design and engineering practice,it is impossible to effectively control the grouting process and ensure the grouting effect.Therefore,by means of laboratory test,theoretical derivation,numerical analysis,comparative verification and numerical simulation,this paper constructs a slurry diffusion model of Newtonian fluid and viscotime-varying fluid in horizontal grouting hole of karst inclined fissure aquifer,and carries out comparative verification through model test and numerical simulation.The variation rules of grout diffusion trace and diffusion distance of inclined fracture under different factors are calculated and analyzed.Research results show that the influence characteristics of slurry diffusion morphology and dip angle calculated by theoretical calculation are consistent with the physical model test results and numerical simulation results of slurry diffusion in inclined fractures.In a single fracture of a Karst aquifer,under different grouting pressures,crack inclination angles(excluding 0°),crack openings and grout water-cement ratios,the grout diffusion pattern is an approximate elliptical shape symmetrical along the central vertical line.The trace in the middle of the upper fissure shows slightly concave feature distribution,and the maximum and minimum grout diffusion distance appear at azimuth angles of 180°and 0°respectively.The range of grout diffusion trace increases with the increase of grouting pressure,fracture opening and grout water-cement ratio,and the increase range of grout diffusion trace is greater than that of grout at the bottom.The range of grout diffusion trace increases and decreases with the increase of fracture inclination angle in the lower and upper fractures respectively.Under the same conditions,the grout diffusion distance in the crack above the horizontal grouting hole is larger than that in the bottom crack,and the distance shows a multiplier increase in the wide-open crack scale.