岩土压花锚抗拔试验研究

普通预应力锚索的常见破坏模式是钢绞线与注浆体脱黏,为防止该类破坏模式的发生并增强内锚固段的锚固能力,将结构工程中的压花锚引入到岩土锚固工程中并进行较大改进,设计8种不同配合比的水泥基注浆体,将压花锚、普通锚锚固在中风化砂岩中,通过抗拔试验获得岩锚的荷载-位移全过程曲线。结果表明:压花结构在注浆体里产生楔形效应,导致压花锚的荷载传递机理与普通锚不同,其承载强度显著高于对应的普通锚,降低了岩锚承载强度对内锚固段长度及注浆体力学性能改变的敏感性。压花锚的上述特性有利于提高锚固工程筋材的利用效率,减少用锚数量,降低工程造价,增强锚固系统的安全可靠度。

Pull-out Tests of Bulb Anchor in Geotechnical Anchorage Engineering

Debonding of interface between steel strand and grout is the dominant failure model of conventional prestressed anchor cable,and in order to avoid the debonding,the bulb anchor of structural engineering is modified appropriately and used in geotechnical anchorage engineering to enhance the anchorage capacity of embedment section.Eight cement-based grouts with different mixing ratios are designed,in which bulb and conventional anchor cables are embedded in medium-weathered sandstone.Then the complete load-displacement curves of the rock anchors are obtained by pull-out tests in laboratory.The test results indicate that load-transfer mechanism of conventional anchor and bulb anchor is different obviously due to wedging effect of bulb structure,the bearing strength of bulb anchor is markedly higher than that of conventional anchor,and the bulb structure decreases the sensibility of bearing strength of rock cable bolt to embedment length and mechanical performance of cement-based grout.These characteristics of bulb anchor can elevate the utility efficiency of cable materials,decrease the amount of anchors,reduce the project costs and enhance the safe reliability of anchorage system.So it is worthy of applying bulb anchor popularly to the actual engineering.