聚丙烯纤维与土壤稳定剂联合改良煤系土的力学特性与微观机理

Mechanical properties and microscopic mechanism of improving coal bearing soil by combining polypropylene fiber and soil stabilizer

针对煤系土遇水极易崩解软化,其填筑的路基在降雨时易发生较大沉降与边坡坍塌滑坡,提出利用聚丙烯纤维与土壤稳定剂联合改良煤系土力学性能。采用扫描电子显微镜(SEM)和低场核磁共振技术研究土壤稳定剂、聚丙烯纤维及两者联合改良对煤系土力学性能及微观结构的影响。研究发现:土壤稳定剂能明显提升煤系土的水稳定性,煤系土抗剪强度与土壤稳定剂掺量基本呈线性正相关;煤系土的抗崩解能力和抗剪强度,随聚丙烯纤维掺量的增加先升高后降低,在掺入量为0.5%时达到最大;聚丙烯纤维与土壤稳定剂的掺入能使煤系土中的土颗粒呈片状叠起重新排列,形成纤维-稳定剂-土颗粒致密稳定基体,这是联合改良煤系土力学性能显著提升的关键。

In response to the technical challenges of coal bearing soil being prone to collapse and softening when encountering water,which can cause severe settlement of the filled roadbed and slope collapse under rainfall conditions,a combination of soil stabilizers and polypropylene fibers is proposed to improve the physical and mechanical properties of coal bearing soil.The microstructure changes and pore structure evolution laws of coal bearing soil improved by the combination of polypropylene fibers and soil stabilizers with different dosages were tested by using scanning electron microscopy and low field nuclear magnetic resonance technology.The research results found that soil stabilizers can significantly improve the anti-disintegration ability of coal bearing soil,and the dosage of soil stabilizers has a basically positive linear relationship with the shear strength of coal bearing soil.The addition of polypropylene fibers will improve the anti-disintegration ability of coal bearing soil,but there is a critical value for its dosage(0.5% in this experiment),beyond which the anti-disintegration effect of coal bearing soil will be weakened.Through microscopic analysis of SEM images and low field nuclear magnetic resonance T2 spectrum curves,it was found that the addition of soil stabilizers and polypropylene fibers can cause soil particles in coal bearing soil to stack and rearrange in a sheet-like manner,forming a dense and stable matrix of fiber stabilizer soil particles.This coupling mechanism is the key to significantly improving the mechanical properties of coal bearing soil through joint improvement.It is feasible to combine soil stabilizers and polypropylene fibers to improve coal bearing soil,providing a new approach for improving the road properties of coal bearing soil.