单向及多向浸水条件下泥岩膨胀变形试验研究

泥岩浸水膨胀变形将导致构筑物地基上拱病害,为研究浸水方式对膨胀土膨胀变形的影响,以兰新铁路第二双线一处典型膨胀泥岩为研究对象,通过单向浸水(包括上部和底部渗透)和三向浸水方式进行了重塑泥岩膨胀变形试验。试验结果表明:不同浸水方式下土体达到膨胀稳定的时间不同,三面浸水方式较单向浸水方式下所需时间短。试验初期单向底部浸水膨胀变形速率较顶部浸水时小,三向浸水膨胀变形速率随注水孔增多而增大。通过试验数据进一步分析发现,三面浸水方式下膨胀变形量与浸水过程吸水量呈良好幂指数关系,单向浸水两者呈良好对数关系,土体浸水方式对膨胀量计算模式有重要影响。通过对比不同浸水方式下膨胀速率及膨胀变形量变化规律,为膨胀土地基设计和预警提供理论支撑。

Experimental study on expansive deformation of mudstone under unidirectional and multidirection water-soaking conditions

The swelling and deformation of mudstone will cause arch disease on the foundation of structures. In order to study the effect of water soaking mode on the deformation of expansive soil，an experiment of remodeling expansive deformation of mudstone is made through the modes of unidirectional water-soaking ( including the infiltrations from both the upper part and the bottom) and tri-directional water-soaking by taking the typical expansive mudstone at a position of the second dual-line of Lanzhou to Xinjiang Ｒailway as the study object. The experiment result shows that the time to reach the stabilization of the expansion is different for the soil masses under different water-soaking modes and the time necessary for the tri-directional water soaking mode is shorter than that of the unidirectional water-soaking mode. At the early stage，the initial expansive deformation rate from the bottom water-soaking is less than the water-soaking from its top，while the expansive deformation rate from the bottom water-soaking is less than that from the top water-soaking and expansive deformation rate for the tri-directional water-soaking mode is increased along with the increase of the number of water-injection holes. Through the further analysis on the experiment data，it is found out that the expansive deformation amount shows a better exponentiational relationship with the water-sorption amount of the process under the tri-directional water-soaking mode，while both of them present a better logarithmic relationship for the unidirectional water-soaking mode，thus the water-soaking mode of soil mass has an important influence on the calculation mode for the expansive amount. Through the comparisons made between the laws of both the expansive rates and the expansive deformation amounts under different water-soaking modes，a theoretical support is provided for the design and early warning of expansive soil foundation.