新型拉压复合型锚杆锚固性能研究Ⅲ:现场试验

Analysis of anchorage performance on new tension-compression anchor Ⅲ field test

针对传统拉力型锚杆存在受力集中、锚固体与岩土体界面黏结强度发挥不充分、抗拔承载力偏低的问题,研发了一种新型拉压复合型锚杆。通过开展现场破坏性试验,对拉力型锚杆及拉压复合型锚杆的承载能力、荷载位移曲线及应变数据进行分析,结果表明:3组拉压复合型锚杆TC12-3、TC11-1、TC21锚杆的平均破坏荷载分别提高至拉力型锚杆的2.81,2.01,2.52倍;拉压复合型锚杆套管内的拉力传递损失率最大为20.5%,在自由段内的拉力传递损失率最大仅为6.8%,拉力传递损失主要发生在承压锚固段上;TC12-3锚杆的受拉锚固段长度最短,单位受拉锚固段长度分担荷载最高;TC21-1锚杆的承压锚固段最短,单位承压锚固段长度分担荷载最高;锚杆破坏时,TC12-3、TC11-1、TC21-1锚杆的受拉承载系数分别为0.398,0.470,0.600;且TC11-1锚杆表现为承压锚固段与受拉锚固段同时破坏,TC12-3、TC21-1锚杆表现为先后破坏;拉压复合型锚杆锚固性能显著提高主要是由于荷载分解作用,界面剪应力双向传递机制及短锚承载效应;从荷载位移曲线来看,拉压复合型锚杆具有较好的抗变形能力,在岩土锚固工程中,具有显著的优势和广阔的应用前景。

The new tension-compression composite anchor(TC-anchor)is developed to overcome the shortcomings of the traditional tension anchor(T-anchor),such as stress concentration,insufficient bonding strength between anchorage body and soil mass,and low uplift bearing capacity.The bearing capacity,load-displacement curves and strain data of T-anchor and TC-anchor are analyzed,based on the field destructive tests.The results show that the average destructive loads of three groups of TC-anchor,TC12-3,TC11-1 and TC21,increase to 2.81,2.01,2.52 times those of T-anchor,respectively.The maximum tension loss rate in the rebar hole is 20.5%and only 6.8%along the free anchorage length,and therefore the tension loss occurs mainly along the compression anchorage body(CAB).The tension anchorage body(TAB)length of TC12-3 anchor is the shortest,and therefore the bearing loads of unit TAB length are the highest.The CAB length of TC21-1 anchor is the shortest,and therefore the bearing loads of unit CAB length are the highest.When the anchor is destructed,the tension bearing coefficients of TC12-3,TC11-1,TC21-1 are 0.398,0.470,0.600,respectively,and the CAB and TAB of TC11-1 are destructed at the same time,while those of TC12-3 and TC21-1 are destructed successively.The significantly increased anchorage performance of TC-anchor is mainly due to the decomposition of the loads,the two-way transmission mechanisms of the interface shear stress and the bearing effect of short anchor.It can be seen from the load-displacement curves that the TC-anchor has better deformation-resisting capability.Therefore,it has significant advantages and broad application prospects in geotechnical anchorage engineering.