锚杆-土体界面剪切特性影响因素试验研究

采用自行设计的室内锚杆-土体界面剪切试验装置模拟锚杆抗拔过程,共开展了72组剪切试验,深入研究了有无预压、土体含水率和压实度3个因素对锚杆-土体界面剪切特性影响。试验结果表明:锚杆-土体界面剪应力随剪切位移的提高而提高,但是当剪切位移达到一定值后,锚杆-土体界面剪应力逐渐弱化或被破坏,并出现锚杆-土体界面剪切位移增加而剪应力降低的现象;土样含水率和压实度对极限剪应力的发挥有十分重要的影响,含水率等于或略大于最佳含水率的土体有利于界面极限剪应力的提高,土体压实度越大,极限剪应力也越高;对于有预压情况,剪切试验中当竖向压力低于预压力时,预压力对于锚杆-土体界面极限剪应力有明显的增强效应,但随着土体上覆压力增大,预压力的增幅效果逐渐减弱,甚至可能出现不利于极限剪应力发挥的现象。

An Experimental Study on the Influencing Factors of Shear Characteristics of Anchor-Soil Interface

72 sets of shear tests have been carried out by using a self-designed indoor anchor-soil interface shear test device to simulate the pull-out process, followed by an in-depth study on the effects of three factors on the shear characteristics of the anchor-soil interface, including the presence or absence of preloading, the moisture content of the soil and the degree of compaction. The results show that the shear stress of the anchor-soil interface increases positively with the shear displacement, while with the shear displacement reaching a certain value, the anchor-soil interface gradually weakens or destroys, meanwhile the shear stress decreases with the increase of shear displacement of anchor-soil interface. The water content and compactness of soil sample have a very important influence on the development of ultimate shear stress. The soil with water content equal to or slightly greater than the optimal water content is conducive to the improvement of ultimate shear stress; the greater the compactness of soil, the higher the ultimate shear stress. Under the preload condition, when the vertical pressure is lower than the preload in the shear test, the preload has a significant enhancement effect on the ultimate shear stress of the anchor-soil interface, while with the increase of the overburden pressure, the increase effect of the preload gradually decreases, with even the disappearance of the phenomenon that is not conducive to the exertion of the ultimate shear stress.