岩土体吸水膨胀应力系数的试验研究

Experimental research on water absorption expansion stress coefficient of rock and soil mass

基于岩土体膨胀性是其含水量的函数的认识,提出了岩土体吸水膨胀应力系数的概念。从膨胀应力与含水率的变化关系出发,研制出吸水膨胀应力系数试验装置;根据试验得到的膨胀应力与含水率增量的关系曲线和计算得到的岩土体吸水膨胀应力系数,对不同状态与类型重塑土样吸水膨胀应力系数的变化规律进行了深入研究。试验研究结果表明:试验装置所测土样的最终含水率误差在1.0%左右,能够较好地得到不同岩土体的吸水膨胀应力系数;由于黏土颗粒水化程度的不断增加,各岩土体的膨胀应力都随含水率的增加而增大,且膨胀应力与含水率增量呈线性关系;初始含水率15.0%条件下云南呈贡强膨胀土、成都弱膨胀土、成都粉质黏土的膨胀应力系数分别为92.2(kPa/%)、42.6(kPa/%)、0.9(kPa/%),是由于不同类型岩土中黏粒含量的差别,导致不同类型岩土体的膨胀应力系数有较大的差别;膨胀应力系数能够有效地区分岩土体的膨胀性,可以用膨胀应力系数对岩土体的膨胀性进行分类。

Based on the understanding that the expansibility of rock and soil mass is a function of water content,the concept of water absorption expansion stress coefficient of rock and soil mass is proposed.Starting from the relationship between the expansion stress and the water content,a test device for water absorption expansion stress coefficient is developed.According to the relationship curve between the expansion stress and the increase of water content obtained by the test and the calculated water absorption expansion stress coefficient of rock and soil mass,the change law of the water absorption expansion in different states and types is studied in depth.The experimental research results show that the error of final water content of the soil sample is about 1.0%,and the water absorption expansion stress coefficient of different type of rock and soil mass can obtained effectively.Due to the increasing hydration degree of clay particles,the expansion stress of each rock and soil mass increases with the increase of water content,and the expansion stress is linearly related to the increase of water content.The water absorption expansion stress coefficient of the Chenggong(Yunnan Province)expansive soil,Chengdu expansive soil,and Chengdu silty clay are 92.2(kPa/%),42.6(kPa/%)and 0.9(kPa/%)respectively under the initial water content of 15.0%.Because of difference of clay content in different types of rock and soil mass,there is a large difference in the water absorption expansion stress coefficient of different types of rock and soil mass.The water absorption expansion stress coefficient can effectively distinguish the expansibility of rock and soil mass,and it can be used to classify the expansibility of rock and soil mass.