硅溶胶物性及其注浆改性泥岩的试验研究

Experimental study on physical properties of silica soil and grouting modified mudstone

基于硅溶胶黏度与凝胶时间、润湿性与亲和力、凝胶体形变以及强度等物性表征,自主研制稳压注浆实验系统,研究硅溶胶在泥岩中的注浆渗透规律以及注浆改性泥岩的强度、孔裂隙及渗透性演化规律。研究结果表明:加入催化剂后硅溶胶黏度随时间延长呈复合指数关系递增,凝胶时间与其SiO2,Na2O含量和催化剂用量有关,SiO2,Na2O含量和催化剂用量越小所需时间越长;硅溶胶凝胶后存在一定的干缩现象,养护环境湿度越小干缩越严重;凝胶体的应力-应变曲线与岩石类材料相似,存在峰前应力跌落和峰后应力分级跌落现象,随养护时间延长,凝胶体强度增加,破坏时脆性特征愈发明显;注浆后岩样的单轴抗压强度不同程度降低,且与注浆压力和时间负相关,相同条件下,随硅溶胶内SiO2,Na2O含量增加强度增大;破坏形式由注浆前的剪切劈裂破坏为主转变为注浆后的剪切滑移破坏、折断破坏和鼓形破坏等多种破坏形式共存。注浆前后岩样孔隙形态分布变化不大,但孔径大于20 nm孔隙的孔容小于注浆前,渗透率显著降低。

Based on the viscosity and gel time,wettability and affinity of silica sol,and it¢s gel deformation and strength were characterized,an experimental system of steady pressure grouting was developed.The law of grouting permeability of silica sol in mudstone and the evolution law of strength,pore fracture and permeability of grouting modified mudstone were studied.The results show that after adding catalyst,the viscosity of silica sol increases composite exponentially with time,and the gel time is related to the content of SiO2 and Na2O of silica sol and the amount of catalyst,the smaller the content of SiO2 and Na2O and the amount of catalyst is,the longer the gel time is.There is a certain phenomenon of dry shrinkage after silica sol gel,and the smaller the humidity of the curing environment is,the more serious the dry shrinkage is.The stress-strain curve of gel is similar to that of rock materials,and there are stress drop in pre-peak and post-peak.With the extension of curing time,the strength of gel increases,and the brittleness characteristic becomes more and more obvious during failure.After grouting,the uniaxial compressive strength of rock samples decreases in varying degrees,and is negatively related to grouting pressure and time.Under the same conditions,the strength increases with the increase of SiO2 and Na2O content in silica sol.The failure mode changes from the shear splitting failure before grouting to the coexistence of shear slip failure,fracture failure and drum failure after grouting.The pore shape distribution of rock samples has little change before and after grouting,but the pore volume of pore size larger than 20 nm pore is smaller than that before grouting,and permeability decreased significantly.