Construction Technology and Pull-out Test of Underreamed Anchor in Expansive Soil
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摘要: 改变锚固体直径和形状是直接提高锚杆抗拔承载力的重要途径。在膨胀土地层采用机械挤压扩孔工艺施工多段扩体锚杆,进行多级循环加载试验,根据锚杆的荷载–位移曲线确定锚杆破坏模式为杆体与锚固体之间黏结界面破坏。试验结果表明,膨胀土地层多段扩体锚杆施工工艺可行,多段扩体试验锚杆抗拔承载力相对于未扩孔锚杆提高1倍左右,但扩大段间距减小对锚杆承载力提高幅度不大。试验结果可供进一步研究膨胀土锚杆承载力影响因素以及锚杆破坏机理参考。Abstract: To enlarge anchorage diameter and to make a change in shape of anchorage body are critical methods to improve bearing capacity of anchor directly. In the expansive soil, the mechanical extruding reaming process was used to construct the multi section underreamed anchors, and the multi-stage cyclic loading test was carried out. According to the load-displacement curve, the failure mode of the anchor is determined as the failure of the bonding interface between the rod and the anchorage body. The test result shows that the construction technology of underreamed anchor in expansive soil layer is feasible. The uplift bearing capacity is one time higher than general anchorage. The bearing capacity value of underreamed anchors increases with decreasing anchor spacing, but the increase range is rarely. The test results could provide reference for the study of the influencing factor of anchorage bearing capacity and failure mechanism of anchorage.
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Key words:
- expansive soil slope /
- underreamed anchor /
- construction technique /
- pull-out
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表 1 杆材物理力学参数
锚索截面积/mm2 极限强度标准值/kN 弹性模量/MPa 726 1350 1.95×105 表 2 锚杆极限承载力取值
编号 极限承载力/kN 平均值/kN 对应位移/mm A1 313 301 14.3 A2 295 17.2 A3 295 13.9 B1 258 288 18.1 B2 295 11.2 B3 313 10.7 -
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