软土地区压力分散型锚索极限抗拔力的现场试验研究

Field Test Study on Ultimate Pullout Force of Pressure Dispersed Anchor Cables in Soft Soil Area

压力分散型锚索作为一种新型的预应力锚固技术以结构设计合理、材料经济、锚固效果好等诸多优点而被广泛应用于岩土工程。然而,对于该类型锚索锚固机理的认识及进行支护设计时,尤其是在软土地区,依靠地方经验性较强且无明确规范参考。通过现场试验,以具体工程为依托,对三单元式压力分散型锚索进行极限拉拔试验研究。经对比试验所得Qc～s、Q～s、Q～se及Q～sp曲线,详细分析了压力分散型锚索在整个极限拉拔过程中锚固段的工作状态及破坏机理并建议以锚索塑性位移与弹性位移的比值变化作为判定压力分散型锚索工作状态的主要参考。试验结果同时得到该地区三单元式压力分散型锚索的极限抗拔力为500kN,为软土地区压力分散型锚索支护设计提供了实测资料及理论参考。

The pressure dispersed anchor cable was applied extensively in geological engineering as a new advanced anchoring technique due to many advantages,such as reasonable structural design,low cost,good anchoring effect and so on.However,the support design method depended on local experiences in most cases and the working state of the pressure dispersed anchor cable could not be recognized clearly by designers,especially in soft soil area.Based on the results of field pullout test of three-unit pressure dispersed anchor cable in soft soil area,the differences between Qc ～ s、Q ～ s、Q ～ se and Q ～ sp curves were analyzed by contrast in detail.The analysis results show that the ratio of plastic displacement to elastic displacement should be advised as main reference for evaluating anchoring effect of the pressure dispersed anchor cable.It is also pointed out that 500KN ultimate pullout force provided by three-unit pressure dispersed anchor cable would be used as anchorage segment located in silty clay layer.