基坑支护结构深层水平位移线型及危险点的判定

Research on the Inclination Curve Type and Dangerous Point Judgment for Deeply Horizontal Displacement of Retaining Structures During Foundation Excavation

基坑深层水平位移的变化曲线同时受支护形式、地质条件及周边建筑荷载等多种因素的影响,测斜曲线的形态各不相同,在复杂条件下甚至出现实测值超过控制值但基坑仍旧安全的情况,即水平位移最大值处并非结构最危险点。通过对8个典型基坑支护项目的105条测斜曲线线型的统计归类,并将各自形态与其受力特征相互关联;在此基础上提出一种用相对位移判断桩身危险点的方法。结果表明,根据形状特征测斜曲线可大致分为抛物线型、开口型、波浪型、反S型和其他五大类;用相对位移法找出支护结构危险点的方法基本可行,支护结构应力与相对位移呈线性关系,随着相对位移偏移值的增大而增大。

The variation curve of the deeply horizontal displacement of foundation excavation is influenced by many factors such as retaining forms,geological conditions and surrounding building loads.Therefore,the shape of the inclination measurement curve is different.In complex conditions,even the actual measured value exceeded the control value,the slopes of foundation still safe,namely,the maximum horizontal displacement was not the most dangerous point of the structure.Therefore,105 inclination curves from 8 typical retaining projects of foundation excavation were statistically classified,and shapes of the curves and their force characteristics were correlated with each other;as well,a method for hazard judgment of piles by relative displacement was proposed.The results showed that the inclination curves could be roughly divided into five categories:the parabo type,the open type,the wave type,the inverse S type and the other according to the curve characteristics;the method for finding the dangerous points of the retaining structure by the relative displacement method was basically feasible.The stress of the retaining structure had a linear relation with the relative displacement,which increased with the increase of the relative displacement offset value.