带褥垫层刚-柔性桩复合地基工程性状的试验研究

为充分调动地基土参与基础的共同工作,近年来我国土木工程界根据工程实践经验,提出用柔性短桩处理浅层软弱土、刚性长桩控制沉降、褥垫层调整和改善桩土应力分担比的带褥垫层刚-柔性桩复合地基形式。为研究这种新型复合地基的工程性状,本文作者在杭州某采用该种地基的七层住宅楼基底埋设压力盒进行现场观测。实测数据表明,在垫层的作用下,桩土荷载分担在加载初期的弹性阶段近似按各自的相对刚度分配,随着上部荷载的增加,浅层地基土和柔性桩逐渐进入非线性状态,新增荷载主要由刚性桩来承担。本文结果为进一步的理论研究和工程设计提供了有益的依据。

Experimental study on behavior of rigid-flexible pile raft foundation with cushion

A new type of composite foundation to mobilize shallow subsoil participating in the interaction of foundation sufficiently was proposed by civil engineers of China from engineering practices. In this composite foundation, the short-flexible piles were used to strengthen the soft subsoil, the long-rigid piles were used to reduce the settlement and the cushion beneath the raft was used to redistribute and modify the stress ratio of piles to subsoil. It was applied to the ground improvement of a 7-story building in Hangzhou City. In order to explore the behavior of the new type foundation, some pressure cells were embedded in the foundation and observed in site. In the early stage of loading, these piles and subsoil were still in elastic behavior and the load sharing ratios of piles to subsoil were nearly distributed by the relative rigidity of their materials under the action of cushion. With increasing of total load, the shallow subsoil and flexible piles were in nonlinear stage, and then the increasing of load was mainly shared by rigid piles. The test data provided useful information for theoretical analysis and engineering design.