化学注浆固结砂微观孔隙与力学特性研究
Study on mechanics and micropore characteristics of chemically grouted sand
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摘要: 化学注浆是预防与治理采掘过程中导水裂隙带沟通上覆厚松散含水层诱发采煤工作面突水溃砂灾害的常用手段。为了研究化学注浆固结砂的微观孔隙、渗透与力学特性的变化规律，采用压汞试验、3D-XRM系统、SLB-1型三轴剪切渗透仪与单轴压缩试验手段，着重分析了化学注浆固结砂的微观孔隙特征、渗透系数、单轴抗压强度、普氏系数的变化规律。试验所选用的化学浆液为改性脲醛树脂，草酸溶液为催化剂，可以调节与控制化学浆液的胶凝时间。研究结果表明：试样的累计进汞曲线为S型，分为4个阶段，分别为缓慢进汞阶段、加速进汞阶段、减速进汞阶段、停滞进汞阶段，退汞率在52.56％～99.46％，半开放孔隙居多，且孔隙间的连通性差；靠近浆液劈裂脉的位置孔隙充填率更高，抗渗性能更好；化学注浆固结砂的平均渗透系数为7.23×10-6 cm/s；依据岩石的普氏系数分级方法，化学注浆固砂样可以达到坚固的状态，说明化学注浆后，松散砂样的坚硬程度得到了明显提高，可以达到很好的固砂减渗效果。Abstract: Chemical grouting is a common method to prevent and control water and sand inrush disaster in coal mining face caused by overlying thick unconsolidated aquifer connected with water flowing fractured zone. In order to study the variation law of micropore, permeability and mechanical properties of chemical grouting consolidated sand, mercury injection test, 3D-XRM system, SLB-1triaxial shear permeameter and uniaxial compression test are mainly used. The variation law of pore characteristics, permeability coefficient, uniaxial compressive strength and Protodyakonov coefficient of chemical grouting consolidated sand are emphatically analyzed.The chemical slurry used in the experiment is modified urea formaldehyde resin, oxalic acid solution is catalyst which can adjust and control the gelation time of chemical slurry. The main conclusions are as follows: the cumulative mercury curve of the sample is S-shaped, which can be divided four stages, namely slow mercury entry stage, accelerated mercury entry stage, decelerated mercuryentry stage and stagnated mercury entry stage;the mercury removal rate is between 52.62% and 99.46%, most of the pores are semi open with poor connectivity; the pore filling rate is higher and the impermeability is better near the slurry splitting vein; the average permeablity coefficientof the test samples is 7.23×10-6cm/s. According to the grading method of rock's Protodyakonov coefficient, the chemical grouted sand can achieve a solid state, which hardness of loose sand sample has been significantly improvedafter chemical grouting, and a good effect of sand consolidation and seepage reduction can be achieved.
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