关于锚杆预应力锁定值取值的探讨  

Discussion on the prestressed locking value of anchor

作　　者：张功磊 Zhang Gonglei(Sichuan Shengtai Architectural Survey and Design Co.,Ltd.,Chengdu 610031,China)

机构地区：[1]四川盛泰建筑勘察设计有限公司,成都610031

出　　处：《工程勘察》2024年第9期5-11,共7页Geotechnical Investigation & Surveying

摘　　要：以《建筑基坑支护技术规程》(JGJ 120-2012)为例,该规范在锚拉式支护结构设计中提出锚杆预应力锁定值宜取锚杆轴向拉力标准值的(0.75~0.9)倍,在执行规范设计过程时,需要运用弹性支点法求解支点力并据此求解锚杆轴向拉力。支点力的大小随锚杆预加力(锁定值)的增大而增大,同时锚杆轴向拉力标准值也相应增大,在满足规范建议取值范围的前提下,会出现得出的支点力过大,锚杆拉力过大,甚至会出现支护结构反向变形的情况,据此设计会造成支护结构不必要的浪费。通过对不同锚杆预加力大小得出的支点力、锚杆拉力、支护桩身位移及支护桩内力的对比分析,得出该规范的取值建议并不合理。同时从岩土工程师角度对其它规范中类似条款进行分析,最后提出在锚杆设计过程中锁定值的合理取值原则。该原则对岩土工程师设计预应力锚杆具有一定的借鉴意义。Taking the "Technical specification for retaining and protection of building foundation excavations"(JGJ120-2012) as an example,the specification proposes that the(0.75~0.9) times of the axial tension standard value of anchor is the prestressed locking value of the anchor in the design of the anchor-pull support structure.When carrying out the specification design process,it is necessary to use the elastic fulcrum method to solve the fulcrum force and accordingly solve the axial tension of the anchor.The magnitude of the fulcrum force increases with the increase of the anchor preload(locking value),and the axial tension standard value of anchor also increases accordingly.Under the premise of meeting the value range recommended by the specification,the fulcrum force is too large,the axial tension standard value of anchor is too large,and even the reverse deformation of the support structure may occur.The design based on this will cause unnecessary waste of the support structure.Through the comparison and analysis of the fulcrum force,anchor tension,support pile body displacement and support pile internal force obtained from different anchor prestressed locking values of anchors,it is concluded that the suggestion value of the specification is not reasonable.At the same time,from the perspective of geotechnical engineers,the similar clauses in other codes are analyzed,and finally the principle of the reasonable value selection of locking values in the process of bolt design is proposed.This principle has certain reference significance for geotechnical engineers to design the prestressed anchors.

关 键 词：锚杆预应力锁定值 锚杆轴向拉力标准值 弹性支点法 支点力 

分 类 号：TU432[建筑科学—岩土工程]