桩体刺入全过程褥垫层的工作特性

褥垫层是复合地基的核心构成,能协调桩、土之间的差异变形。在桩体刺入褥垫层的过程中,褥垫层的工作特性在发生变化,这方面研究还较少见。通过室内模型试验,观测桩体刺入褥垫层不同深度的桩顶压力、桩顶位移量、褥垫层的变形等试验结果,来研究褥垫层的全过程工作特性,并分析桩间土压力、桩径等对褥垫层的影响。结果表明:在桩体刺入过程中,褥垫层存在压密变形、剪切变形、压碎变形3个阶段;桩间土压力对褥垫层的整个变形过程均有影响,在其他条件相同时,褥垫层抵抗的桩顶压力、褥垫层的承载厚度均随着桩间土压力的增大而增大;桩径对褥垫层的影响主要在压碎变形阶段,褥垫层的承载厚度随桩径的增大而增大,且基本呈线性增长。

Working characteristics of cushion subjected to pile penetration

Cushion is the core of composite foundation, which can coordinate the differential deformation between piles and soils. The working characteristics of the cushion may change when the pile penetrated into the cushion, which is lack of inrestigation at present. In this paper, by means of model tests, the working characteristics of the cushion during the penetrating of pile were analyzed by measuring the pile top''s pressure, displacement and deformation of cushion. Besides, the effects of the pressure between piles and soil, and the pile diameter on the cushion were analyzed. The results show that, during penetraton process, there are three different deformation stages, i.e., compaction deformation, shear deformation and crush deformation. The pressure between piles and soils affects the whole process of the cushion''s deformation, and the bearing capacity and the bearing thickness of the cushion are increased with the pressure. The effect of the pile diameter on the cushion is signigicant in the crushing deformation stage. The bearing thickness of the cushion increased linearly with the pile diameter.