水平荷载作用下压力型扩大头锚杆承载特性试验研究

Experimental study on failure characteristics of pressured under-reamed anchors under horizontal loads

通过自行研制的模型试验装置,利用PIV技术研究水平荷载作用下压力型扩大头锚杆力学特性以及周围土体位移发展机理。试验结果表明,压力型扩大头锚杆的受力过程可分为侧摩阻力阶段、过渡阶段和端部阻力阶段,在每个阶段转变之间荷载位移曲线会出现"拐点"。基于数字图像分析,提出压力型扩大头锚杆扩大头锚固段近端土体临界位移场影响范围呈"灯泡型",且当扩大头锚固段长径比超过3∶1后,随着继续增大长径比对扩大头锚固段近端的位移场范围基本无影响。

Through a self-developed model test device and PIV technology,the mechanical characteristics of pressured under-reamed anchors under horizontal loads and the development mechanism of the surrounding soil displacement are studied.The test results show that the stress process of the pressured under-reamed anchors can be divided into lateral friction stage,transition stage and end resistance stage,and there will be an"inflection point"in the load-displacement curve between the transitions of each stage.According to the image analysis,it is proposed that the influence range of critical displacement field of soil around the under-reamed anchorage segment of pressured anchor is"bulb-shaped".When the length-diameter ratio of the enlarged head anchoring section exceeds 3∶1,the displacement field at the proximal end of the under-reamed anchoring section is basically unaffected with the continuous increase of length-diameter ratio.