斥水红黏土最优含水率下的抗剪强度研究

Study on shear strength of water repellent red clay under optimal water content

在相同湿度环境下放置相同时间斥水土含水率明显小于亲水土,故经测定后试样选用最优含水率为初始含水率进行斥水红黏土抗剪强度试验。利用十八烷基伯胺[CH3(CH2)16CH2NH2,简称十八胺]作为斥水剂,采用不同垂直压力、含水率作为变量进行直剪试验,对斥水土、亲水土、斥水土+30%斥水砂3种土进行对比。结果表明,斥水土的斥水度、强度与土壤含水率有密切关系,且在最优含水率下斥水土强度明显大于亲水土,但在相同含水率下亲水土强度大于斥水土,此时斥水土延性降低,在斥水土中加入斥水砂其延性得到提高。斥水土中水分难以进入,基质吸力下降不明显,最优含水率下斥水土黏聚力c较大。

Under the same humidity environment,the moisture content of water repellent soil was obviously less than that of natural soil at the same time.Therefore,after measurement,the sample selects the optimal moisture content as the initial moisture content for the shear strength test of water repellent red clay.Octadecyl primary amine[CH3(CH2)16CH2NH2,referred to as Octadecyl Amine]was used as water repellent,and different vertical pressure and water content were used as variables to carry out the direct shear test.Three kinds of soil,repellent,natural,repellent and 30%repellent sand,were compared.The results showed that the water repellency of water repellent soil was closely related to the soil moisture content,and the water repellent intensity was significantly higher than that of under the optimal moisture content,but the water repellent intensity of natural soil was higher than that of water repellent soil under the same moisture content.At this time,the ductility of water repellent soil was reduced,and the ductility was improved by adding water repellent sand to water repellent soil.The strength and water repellency of soil were related to water content.It was difficult for water to enter the water repellent soil,and the decrease of matrix suction was not obvious,so the cohesion c of water repellent soil was large under the optimal water content.