基于岩体宏细观特征的大型帷幕注浆保水开采技术及应用

Technology and application of large curtain grouting water conservation mining based on macroscopic and mesoscopic characteristics of rock mass

在地下水径流通道处建造帷幕注浆墙体是矿产资源开发与地下水资源保护的重要平衡手段,而随着矿产资源开发强度和深度的增大,建造大型帷幕墙体面临钻探成本高、墙体内外水压差大、墙体截流率低等问题,针对上述问题采用受注介质宏细观特征分析的方法,宏观上研究受注介质发育特征及水文地质条件,细观上基于显微CT分析研究受注介质空隙发育特征和几何参数,宏细观结合综合分析大型帷幕墙体建造科学位置、钻探工艺、注浆材料和适用性配比选取、注浆压力等问题,并利用放水试验、钻孔取芯、钻屑组分判断等手段对帷幕注浆效果进行分析评价。研究结果表明:对于开度较小的裂隙,须采用纯水泥浆液进行升压注浆充填,对于含有较大空洞岩溶地层,可在水泥浆液中掺入粉煤灰进行无压充填灌注;水固比为0.6,0.7,0.8,0.9的水泥浆液,水固比为2.0,1.0,0.8,0.6和对应粉煤灰掺量20%,20%,20%,20%和30%的水泥-粉煤灰浆液结石体的物理力学性质均能够满足帷幕墙体建造要求;帷幕墙体建造最小安全厚度为7.84 m,满足浆液扩散范围和建造效率的注浆压力为4~6 MPa。经检查孔检验,大空洞充填灌注采取的浆液结石体试样饱和抗压强度为11.2 MPa,完全满足墙体强度要求;放水试验中,墙体内外水位差7 d达到140 m、截流率在86.51%以上,墙体截流效果显著,达到设计目标和要求。

The construction of curtain grouting wall at the groundwater runoff channel is an important balance means between the development of mineral resources and the protection of groundwater resources.With the increase of intensity and depth of mining operations,the construction of large-scale curtain wall faces the problems of high drilling cost,large water pressure difference between the inside and outside of the wall,and low closure rate of the wall.In view of the above problems,the authors adopt the method of macro and micro characteristics analysis on the injected medium:macroscopically study the development characteristics and hydrogeological conditions of the injected media,and microscopically study the development characteristics and geometric parameters of the injected media based on the analysis of micro CT,comprehensively analyze the scientific location of large curtain wall,drilling technology,grouting materials and the selection of applicability ratio,grouting pressure and other issues by combining macroscopical and microscopical analysis,and make use of water drainage test,drilling core,drilling cuttings components to analyze and evaluate the curtain grouting effect.The results show that for the cracks with small opening,pure water slurry should be used for pressure grouting filling,and for the karst stratum with large cavities,fly ash can be added into the cement slurry for non-pressure filling.For the cement slurry with water-solid ratio of 0.6,0.7,0.8 and 0.9,the cement slurry with water-solid ratio of 2.0,1.0,0.8 and 0.6 and the cement with corresponding fly ash content of 20%,20%,20%,20%and 30%,the physical and mechanical properties of the fly ash slurry stone can meet the construction requirements of the curtain wall.The minimum safe thickness of the curtain wall is 7.84 m,and the grouting pressure to meet the slurry diffusion range and construction efficiency is 4-6 MPa.According to the inspection of the inspection hole,the saturated compressive strength of the slurry stone sample taken for the filling and pouring of the large cavity is 11.2 MPa,which fully meets the strength requirements of the wall.In the water discharge test,the water level difference between the inside and outside of the wall reaches 140 m in 7 days,and the closure rate is over 86.51%.The closure effect of the wall is significant,which meets the design objectives and requirements.