基于超细材料的全风化花岗岩防渗注浆研究

Research on anti-seepage grouting in completely weathered granite based on superfine materials

针对全风化花岗岩地层注浆过程中存在“吃水不吃浆”、可灌性差以及浆液的稳定性问题,提出了一种新的复合注浆材料,以提高完全风化花岗岩的防渗和力学性能。通过一系列室内试验研究了不同水固比、超细膨润土含量和超细硅酸盐水泥含量对注浆材料工程性能和浆液形成机制的影响,确定了水泥浆的最佳配方,采用微观形貌试验揭示了2种超细材料对浆液流动性、稳定性和结石体强度的作用机理,最后通过现场试验验证了注浆材料的可注性和有效性。结果表明,水固比为1.2、超细膨润土和超细硅酸盐水泥掺量分别为10%、普通硅酸盐水泥掺量80%配方的复合浆液具有很好的流动性、稳定性和抗压强度,漏斗黏度为35.5 s,析水率为2.4%,7 d和28 d的抗压强度均大于5 MPa;复合材料中的超细膨润土的掺量对浆液性能起主导作用,超细膨润土含量及其水化胶体的形态与分布决定浆液稳定性,而适量的超细硅酸盐水泥增加了细颗粒含量,使得胶结体更易填充颗粒间隙,改善了浆液可注性和结石体强度;该复合注浆材料在现场试验中表现优异,具有良好的注浆性能,注浆后形成的墙体在防渗效果和加固性能上均满足设计要求。

[Objective]To solve the problems of"draught without slurry",poor groutability and slurry stability in the grouting process of completely weathered granite,a new composite grouting material is proposed in this paper to improve the anti-seepage and mechanical properties of completely weathered granite.[Methods]Through a series of laboratory experiments,it investigates the effects of different water-solid ratios,superfine bentonite,and superfine Portland cement content on the engineering properties of grouting materials.The formation mechanism of the slurry were studied,and the optimal formula of the cement slurry was determined.The experiment revealed the action mechanism of the two superfine materials on the fluidity,stability,and stone body strength of the grout.Finally,the castability and effectiveness of the grouting material were verified by a field test.[Results]The results show that the composite slurry with a water-solid ratio of 1.2,a content of superfine bentonite and superfine Portland cement of 10%,and a content of ordinary Portland cement of 80%has good fluidity,stability,and resistance.The funnel viscosity was 35.5 s,the water separation rate was 2.4%,and the compressive strengths at 7 d and 28 d were both greater than 5 MPa.The compressive strength and the content of superfine bentonite in the composite material play a leading role in the properties of the slurry.The content of superfine bentonite and the morphology and distribution of its hydrated colloids determine the stability of the slurry,while an appropriate amount of superfine Portland cement increases the content of fine particles,making it easier for the cement to fill the gaps between the particles and improving the injectability of the slurry and the strength of the stone body.[Conclusion]The composite grouting material has excellent performance in the field test and good grouting performance.The wall formed after grouting meets the design requirements in terms of the anti-seepage effect and reinforcement performance.