土层锚杆受力特性及水的影响模型试验

Mechanical characteristics of soil anchor and water influence based on model test

土层锚杆的受力特性是多年来各国学者致力研究的问题之一,通过现场模型试验,对土层锚杆的受力特性进行了研究,改变锚杆周围土体的含水量,分别研究了土体含水量对锚杆P-S曲线、极限抗拔力以及预应力的影响。试验结果表明,轴力及剪应力峰值均在锚固段外端,锚杆的P-S曲线为明显的4段线:弹性阶段,弹塑性阶段、塑性阶段和残余阶段,当含水量较低时,弹性阶段较为明显,当含水量增大时,没有明显的弹塑性阶段,直接由弹性变为塑性阶段,含水量越大,锚杆极限抗拔力越低,且呈反"S"曲线变化规律,预应力张拉刚刚完成后,锚杆的预应力损失很快,预应力的变化和时间呈负指数变化关系,当周围土体含水量增大时,预应力会继续降低。

The mechanical characteristics of soil anchor are studied by model test. In this test, by changing soil water content, to investigate its influence on P - S curve, ultimate pullout porce and prestress of soil anchor. The results show that the axial force and shear stress of out end of anchorage section is biggest. The P - S curve consists of elastic section, elastic-plastic section, plastic section and residual section. The lower the soil water content is, the more significent the elastic section is. With the water content increasing, the elastic-plastic section becomes shorter and shorter, and disappears finally. The higher the soil water content is, the lower the ultimate pullout force of anchor is. The variation of it with soil water content is an inverse sigmoid curve. For a prestressed anchor, the prestress lossing with time is a negative exponential function, and when the soil water content increases, the prestress will continue to decrease.