既有建筑下半盖挖深基坑变形影响因素研究

Study on Influencing Factors of Deformation of Semi-Covered Deep Excavation under Existing Buildings

由于盖板与建筑荷载的存在,既有建筑下半盖挖深基坑承受偏压荷载,对基坑与支护结构变形造成影响。依托南京山西路地铁车站半盖挖深基坑,采用数值模拟手段,研究了既有建筑对半盖挖深基坑变形的影响,得出以下结论:地连墙最大侧移量δ_(hm)随上部建筑层数增大显著增大,随地下室层数增加显著减小;最大侧移位置H_(m)随上部建筑层数增大而上移,随地下室层数增加而下移;既有建筑导致地连墙侧移曲线整体发生向基坑内的移动;随着上部建筑层数的增大,建筑侧坑外最大地表沉降δ_(hm)显著增大,最大地表沉降位置d_(m)向坑外移动;存在地下室时,最大沉降均发生在建筑靠近基坑侧;δ_(hm)随开挖深度H呈二次相关。

Due to the load of the cover plates and surrounding buildings,semi-cover deep foundation pit excavation under the existing building bears an eccentric load,affecting the deformation of excavations and supporting structures.Based on the semi-covered deep excavation of Nanjing Shanxi Road subway station,the influence of existing buildings on the deformation of semi-covered deep excavation is studied by means of numerical simulation,and the following conclusions are drawn:The maximum lateral displacementδ_(hm) of diaphragm wall increases significantly with the increase of the number of upper floors and decreases significantly with the increase of the number of basement floors;The maximum lateral displacement position H_(m) moves up with the increase of the number of storey in the superstructure and moves down with the increase of the number of storey in the basement;Existing buildings cause the lateral displacement curve of diaphragm wall to move into the excavation as a whole;With the increase of the number of storey in the superstructure,the maximum surface subsidenceδ_(hm) outside the building side increases significantly,and the maximum surface subsidence position d_(m) moves outside the pit.When there is a basement,the maximum settlement occurs at the side of the building near the excavation.δ_(hm) has a quadratic correlation with the excavation depth H.