Measured settelements of super-long piles and pile groups for a building of 323 m in height in Wenzhou
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摘要: 根据单桩静载试验和基础沉降实测资料表明：超长单桩在设计工作荷载作用下的桩顶沉降量St主要为桩根据单桩静载试验和基础沉降实测资料表明：超长单桩在设计工作荷载作用下的桩顶沉降量St主要为桩身混凝土压缩量Ss，且侧阻力很大，端阻力发挥很小。超长单桩上部黏性土中桩侧摩阻力充分发挥所需的桩土极限相对位移约17～20 mm。当桩土相对位移大于该极限位移后，桩上部土层发生桩土滑移呈现侧阻软化现象。群桩基础的沉降随着施工荷载水平的增加而增大。其规律为：施工层数很低时（5层以下），主裙楼一体沉降；随着主楼施工层数（8层后）增加，主楼沉降增大，同时由于主楼的“促沉”作用会使得裙楼沉降得以延续；随着主楼施工层数（30层后）继续增加，由于主楼核心筒相对裙楼沉降较大引起的对裙楼的“牵拉作用”会使裙楼出现轻微上翘的现象，但由于总体沉降量较小，所以裙楼、主楼、主楼核心筒的角点和边点沉降值相差不大。群桩效应沉降比Rs随着荷载水平（施工层数）的增大而先增大后减小。Abstract: The data based on the static load tests and settlement observations show that the compression of the piles accounts for a considerable part of the total settlement of the piles under the working loads. Simultaneously, the side resistance of the piles takes a large part while the end resistance of the piles takes a small one. The ultimate pile-soil relative displacement of 17~20 mm is needed for the super-long piles to bring their side resistance into full play at the upper half of the piles in the clay. After that, the soil slides and the friction is degraded. The settlement of pile-group foundation increases as the load becomes larger and larger. The rules are as follows: the main building and the podium settle down simultaneously at low floors (below the 5th floor); then the main building continues its settlement and has a ‘settling promotion effect’ to the completed podium with taller floors (above the 30th floor); after the 30th floor, the podium shows upwarping because of the ‘pulling up effect’ due to the large relative settlement of the tube of the main building’s, while the total settlement is small, so the differential settlement in the edge points and surrounding points of the main building, podium and tube is not obvious. And the settlement ratio of the pile groups first increases and then decreases with the increase of loads.
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