高吸力下广西重塑红黏土吸力与含水率关系试验研究

Experimental tests on relationship between suction and water content of remolded lateritic clay in Guangxi under high suction

吸力对非饱和土的性质有着重要的影响,探讨吸力与非饱和红黏土含水率之间的关系可以有效地服务地方经济。用蒸汽平衡法研究了高吸力段(3~368 MPa)广西贺州红黏土持水特性。研究表明,质量含水率或者饱和度随着控制吸力的增加而减小,随着吸力的降低而增大;本组试验在控制吸力值为21.82 MPa时,曲线存在突变点,此时试样吸排水速率发生比较大的变化;脱湿曲线与吸湿曲线间存在滞回效应,吸力值小于突变点的时候,滞回现象明显。不同初始含水率的土样对应的吸力与含水率间关系曲线基本重合,而吸力与饱和度间关系曲线则不重合,主要与含水率的变化和土体的胀缩变形不成正比有关,孔隙比和吸力间的关系曲线也进一步说明了这一点,因此分析红黏土土水特征时要根据实际情况选用坐标变量。所获结果为当地边坡土体持水特性分析提供了基础数据,有助于该地区工程实践的防灾减灾。

The suction has important influence on the properties of unsaturated soil. To explore the relationship between suction and water content of unsaturated lateritic clay can serve the local economy effectively. The soil-water characteristic curves(SWCC) of unsaturated lateritic clay with different initial water contents in Guangxi are measured by using the vapor equilibrium technique under high suction rang of 3~368 MPa. The results show that the water content or the degree of saturation decreases with the increasing control suction and increases with the decreasing control suction. When the value of control suction is less than 21.82 MPa, the drying or wetting rate of soils is getting down. The hysteresis phenomenon between the drying and wetting curves is more obvious when the control suction is smaller. The relation curves between suction and water content of soil samples with different initial water contents are coincident, but those between suction and saturation are not coincident. The main cause is that the variation in water content is not proportionate to the soil swelling or shrinkage deformation, and the relation curve between suction and void ratio confirms this further. Accordingly we should choose the right coordinate variables for SWCC of lateritic clay according to the actual situation. The results provide basic data for the analysis of soil water holding characteristics in local slope, which makes a contribution to the disaster prevention and reduction of the engineering practice in this area.