非对称开挖局部构件失效对支护体系的影响  

Influence of local component failure on retaining system under asymmetric excavation

作　　者：魏焕卫[1] 武韬 WEI Huanwei;WU Tao(School of Civil Engineering,Shandong Jianzhu University,Jinan 250101,China)

机构地区：[1]山东建筑大学土木工程学院,山东济南250101

出　　处：《河海大学学报（自然科学版）》2022年第6期92-100,共9页Journal of Hohai University(Natural Sciences)

基　　金：山东省自然科学基金(ZR2012EEM016);国家自然科学基金(41272281)。

摘　　要：针对非对称开挖基坑长度方向由局部破坏引发的基坑连续性倒塌问题,利用三维有限元软件PLAXIS 3D,采用构件拆除法对非对称开挖基坑局部构件失效情况下整体支护体系的响应进行了分析。结果表明:支撑失效后,位于失效区的桩产生卸荷效应,土压力降低,而邻近失效区反之,最近的未失效支撑处桩身弯矩增加较大;在支护桩失效后,失效桩同侧的未失效桩桩后土压力和弯矩显著上升,异侧减小;深侧桩通过支撑对浅侧桩产生向基坑外的推挤作用,深侧桩失效后,浅侧桩出现反推挤现象;土体最大沉降量浅侧较深侧小,沉降量随失效桩数增加愈来愈大而沉降范围基本不变;挖深差愈大土压力变化系数及弯矩传递系数愈大;挖深分界线改变对土压力及桩身弯矩影响均很小。提出了考虑连续性破坏时对支护桩配筋弯矩放大以提高支护结构冗余度的设计方法。Asymmetric excavation has become increasingly common with the development of construction and the progressive collapse caused by the local component failure has attracted many attentions. Aiming at this problem, the three-dimensional finite element software PLAXIS 3D is adopted to analyze the response of the whole retaining system to the asymmetric excavation after local component failure through the method of removing component. The results show that when the braces fail, the earth pressure of piles decreases in the failed area because of the unloading effect but is opposite in the adjacent area. Meanwhile, the moments of piles near intact braces increase greatly. The earth pressure and moment of piles on the same side of the failed piles increase greatly, while on the opposite side they decrease as piles get failed. Piles on the deep side push piles on the shallow side through braces, but the displacement reverses when piles on the deep side failed. The value of soil settlement on the shallow side is less than that on the deep side and increases with the increasing number of failed piles, but the range of settlement almost keeps unchanged. Earth pressure variation coefficient and moment transfer coefficient get surge when the depth difference increases. In addition, the change of depth boundary line has little effect on the earth pressure and pile moment. Finally, a design method is proposed to improve the redundancy of supporting structure through enlarging the reinforcement moment of piles.

关 键 词：基坑 支护体系 非对称开挖 局部失效 冗余度 

分 类 号：TU473[建筑科学—结构工程]