膨胀土胀缩性与裂隙性的湿干循环效应

Effects of Cyclic Wetting and Drying on Swelling-shrinkage and Cracking of Compacted Expansive Soil

以压实度分别为100%、95%、90%、85%、80%的荆门黄褐色中膨胀土为研究对象,开展8次湿干循环试验,探索湿干循环过程中膨胀土的体积-裂隙-持水变化规律。结果表明:(1)历经3~7次湿干循环后,膨胀土的体积变化、含水率变化基本可逆。(2)随湿干循环次数增加,膨胀时程曲线、收缩曲线上移,表明湿干循环导致试样体积增大。膨胀稳定时间随湿干循环次数增加而减少,随制样压实度降低而减少。(3)试样脱湿完成后的裂隙面积随湿干循环次数增加而增大,5~6次湿干循环后,裂隙面积趋于稳定。历经足够多次湿干循环后压实中膨胀土裂隙率参考值为7%~10%。(4)每次脱湿完成后浸水,试样裂隙愈合;其中,前4次湿干循环,裂隙完全愈合。

A series of tests for eight wetting-drying cycles were carried out on Jingmen yellow-brown expansive soil under five different initial compactnesses(100%,95%,90%,85%,80%,respectively).And the volume change-cracking-water retention behaviors during wetting-drying cycles were investigated.The conclusions were drawn as follows:(1)After three to seven wetting-drying cycles,the volume change and water content of the expansive soil were reversible.(2)With the increase of the number of wetting-drying cycles,the shrinkage curves and swelling curves moved up,which showed that the volume increase was induced by the wetting-drying cycles.Stability time for swelling decreased with the increase of the number of wetting-drying cycles,and with the decrease of initial density.(3)The crack area of the sample after drying increased with the increase of the number of wetting-drying cycles.And the crack area became steady after five to six wetting-drying cycles.After enough wetting-drying cycles,the reference value of surface crack ratio of compacted expansive soil was 7%~10%.(4)The cracks healed during wetting,and the cracks healed completely in the first four wetting-drying cycles.