引江济淮工程膨胀土水泥改性剂量研究

膨胀土具有遇水膨胀、失水收缩的工程特性,掺加一定量水泥对其进行改性是处理膨胀土的主要方法之一。选取引江济淮工程弱膨胀土,通过对素膨胀土和改性土的自由膨胀率、界限含水率及无侧限抗压强度的试验分析,揭示了水泥掺量和养护日期对引江济淮工程弱膨胀土的物理力学性质的影响。试验结果表明:(1)随掺灰率的增加,改性膨胀土的自由膨胀率、液限、塑性指数均降低,无侧限抗压强度增加;(2)随养护日期的增加,自由膨胀率、液限、塑性指数减小,无侧限抗压强度增大;(3)基于本研究试验结果,同时综合考虑工程实际,建议引江济淮工程弱膨胀土水泥改性剂量为4%。

Cement amount of modified expansive soils in water diversion project from Yangtze River to Huaihe River

The expansive soils have the tendency to expand in wetting and to shrink in drying. The addition of cement is one of the methods to enhance the engineering properties of such soils. The effects of varying cement contents and curing time on the engineering properties of the expansive soils are investigated through the measurements of free swelling index, Atterberg limits and unconfined compressive strength of weak expansive soils along a section of water diversion project from Yangtze River to Huaihe River. The test results show that increasing the amount of cement decreases the free swelling index, liquid limit and plasticity index, whilst the unconfined compressive strength increases. Also, increasing the curing time leads to a reduction in the free swelling index, liquid limit and plasticity index, but an increase in the unconfined compressive strength. After seven days of curing the measured soil properties begin to be stable. Thus, the improvement of the expansive soils by cement takes long time.