羧甲基纤维素、膨润土改良风沙土崩解特性研究

Study on Disintegration Characteristics of Aeolian Soil Modified by Carboxylmethyl Cellulose and Bentonite

在全球变暖的背景下,中国西北地区极端降水呈现上升趋势,严重影响了风沙土的抗崩解能力,加重了该区域的土壤侵蚀问题。为提高风沙土抗崩解特性,采用羧甲基纤维素(CMC)、膨润土对风沙土进行改良,并开展相应的改良风沙土崩解试验,研究不同改良方案下风沙土的抗崩解性,结合扫描电镜试验分析改良风沙土的崩解机理。研究结果表明,土样的崩解破坏过程可分为吸水剥落阶段、孔隙崩解阶段、饱和崩解阶段、残余崩解阶段,未改良土样的吸水剥落阶段持续时间短,无明显残余崩解阶段。随着土样改良剂质量占比的提升,改良土样的吸水剥落阶段延长,崩解速率降低,抗崩解特性增强,其中CMC与膨润土的复合改良方案效果最佳。在微观结构方面,CMC、膨润土主要通过土粒团聚、粒间胶结、孔隙填充三个方面增强土样的抗崩解特性,并且CMC与膨润土改良效果可以相互促进,有效增强风沙土抗崩解特性。

Under the background of global warming, extreme precipitation in Northwest China shows a rising trend, which seriously affects the disintegration resistance of aeolian soil and aggravates the soil erosion problem. In order to improve the disintegration resistance characteristics of the aeolian soil, carboxymethyl cellulose (CMC) and bentonite were used to improve the aeolian soil, the corresponding disintegration test of the improved aeolian soil was carried out to study the disintegration resistance of aeolian soil under different improvement schemes, and the disintegration mechanism of the improved aeolian soil was analyzed in combination with scanning electron microscope (SEM) test. The results show that the disintegration damage process of soil samples can be divided into surface water absorption and spalling, saturating and softening, saturated stabilization, and complete disintegration. Unimproved soil samples have a shorter duration of the absorptive spalling phase and complete disintegration. With the increase in the proportion of the quality of the soil sample ameliorant, the absorptive spalling stage of the amended soil samples is prolonged, the disintegration rate is reduced, the disintegration characteristics of the soil samples are strengthened, and the composite improvement scheme of CMC and bentonite is the best. In terms of microstructure, CMC and bentonite mainly enhance the disintegration resistance of soil samples through soil particle agglomeration, intergranular cementation, and pore filling, and CMC and bentonite can promote each other’s improvement effect, effectively enhancing the disintegration resistance of aeolian soil.