纳米层状硅酸盐复合砂土渗透及微观特性试验研究

Experimental Study on Permeability and Microscopic Characteristics of Nano-layered Silicate Composite Sand

注浆封堵是地下工程渗漏治理工作中常用的方法之一,基于纳米级层状硅酸盐材料的新型渗透注浆技术,相较于传统水泥和化学注浆,具有自渗性好、微扰动及无污染等特性。在充分调研国内外相关研究成果的基础上,选用具有代表性但研究较少的纳米材料——合成锂藻土(Laponite),分别开展其复合土体的变水头渗透试验和冷冻扫描电镜测试。Laponite注浆前后的渗透试验结果对比表明,添加1.5%~3.5%的Laponite,砂土渗透系数可从6.12×10^(-3) cm/s降低至8.99×10^(-5)~6.09×10^(-6) cm/s,抗渗性能得到显著提高。冷冻扫描电图像则直观地说明了Laponite浆液提高土体抗渗特性的微观机理,即孔隙流体改性同时包裹胶结土颗粒。以上研究结果可为同类型注浆材料的研究提供参考和数据。

Grouting is one of the commonly used methods to control leakage in underground engineering.A novel per-meation grouting technology based on nano-layered silicate material is proposed.Compared with traditional cement and chemical grouting,this technology has good self-permeability,micro disturbance,and no pollution.Based on literature review of relevant research,representative but less studied nanomaterial were selected,Laponite was selected as the experimental material.The falling head permeability tests and Cryo-scanning electron microscopy tests were conducted.The comparison of permeability test results before and after Laponite grouting shows that anti-penetrability performance nano composite sand has been significantly improved.Adding 1.5%~3.5%Laponite,the permeability coefficients of sand were reduced from 6.12×10^(-3) cm/s to 8.99×10^(-5) cm/s~6.09×10^(-6) cm/s.Cryo-scanning e-lectron images directly illustrate the microscopic mechanism of Laponite grouting.The pore fluid is modified,and the cemented soil particles are simultaneously wrapped,thus improving the permeability of sand.The above research re-sults can provide reference and data for the same type of grouting materials.