界面粗糙度对土体龟裂影响的试验研究

EXPERIMENTAL STUDY ON EFECT OF INTERFACIAL ROUGHNESS ON DESICCATION CRACKING BEHAVIOR OF SOIL

土体在蒸发干燥的过程中会产生龟裂现象,从而极大地改变其工程性质,引发各种工程地质灾害。为了研究界面粗糙度对土体龟裂的影响,设计了两组龟裂试验,分别在试样容器底部涂抹凡士林(S1)和粘贴砂纸(S2)来改变试样与容器界面的粗糙度。试验过程中,定期对土体裂隙发育情况进行拍照记录,并采用数字图像技术对裂隙几何形态特征进行定量分析,得到不同界面粗糙度条件下土体龟裂的动态发展过程及相关参数,结果表明:(1)土体蒸发过程可分为3个典型阶段:常速率阶段、减速率阶段和残余阶段;(2)龟裂发育过程也可分为3个典型阶段:主干裂隙生成阶段、次级裂隙生成阶段和裂隙扩展稳定阶段;(3)界面粗糙度对龟裂发育过程有重要影响。对于基底相对光滑的界面,土样呈整体向中心收缩趋势,表面几乎不产生裂隙。对于粗糙的界面,受基底摩擦作用,土样表面发育纵横交错的裂隙网络。在不同的裂隙发育阶段,界面粗糙度对裂隙率增长速度影响不同。界面粗糙度越高,最终稳定时的表面裂隙率越低。

In the process of evaporation and drying,soil will cracks,which greatly change the nature of its engineering,triggering a variety of engineering geological disasters. In order to study the effect of interfacial roughness on soil cracking,two kinds of cracking tests are carried out,by applying Vaseline at the bottom of the container（ S1） and posting sandpaper（ S2） to change the interface roughness. During the experiment,the fissure development of the soil is recorded on a regular basis. The geometric characteristics of the fractures are quantitatively analyzed by digital image technology. The dynamic development process and related parameters of soil crack under different interface roughness are obtained. The results show the following aspects.（ 1） Soil evaporation process can be divided into three typical stages： constant rate stage,deceleration rate stage and residual stage.（ 2）Cracks are generally divided into three typical stages： the main fissure generation stage,the secondary fissure generation stage and the fracture growth stabilization phase.（ 3） The interface roughness has an important effect onthe development of the fissure. For the relatively smooth interface of the base,the soil sample tends to shrink to the center as a whole,and the surface hardly produces cracks. For the rough interface,by the role of the base friction,soil surface developed criss-crossing the fissure network. The influence of interface roughness on the growth rate of fissure is different in different fissure development stages. The higher the interface roughness,the lower the surface fissure in the final stability.