软土地基中组合桩承载性状试验研究

Experimental Research on Vertical Bearing Capacity of Composite Piles in Soft Ground

为掌握组合桩(钢筋混凝土桩插入水泥土搅拌桩复合而成的桩)的荷载传递机理、破坏模式和竖向承载力特性,通过对3根14 m长桩的载荷试验和桩身应变的测量,分析了桩身轴力的分布和桩周的侧摩阻力分布及影响组合桩承载力因素。试验得到了组合桩的Q-S曲线、S-logt曲线、桩的极限承载力;试验表明混凝土桩的插入改变竖向荷载的传递规律,形成了从混凝土桩到水泥土再到土的传递模式,更有效地发挥了桩周的侧摩阻力;水泥土的固化效应、混凝土桩的挤土效应和混凝土桩的荷载传递是组合桩高承载力的主要来源。组合桩具有较高的单桩竖向承载力且造价低,在软土地基工程中具有广泛的应用价值。

To study the load transfer mechanism, failure mode and vertical beating capacity of a new-style composite pile formed by inserting a precast concrete pile into a cement mixing pile, in-situ tests of three full-scale composite piles were carried out and axial strains of piles were measured. Based on the experimental results, such as Q-S curves, S-logt curves, limit bearing capacity and axial strain, the distribution on axile force and side resistance of a composite pile, the distribution on side resistance along a composite pile and factors influencing the bearing capacity are analyzed. According to experimental and analytical results, load transfer mode that load is transferred from the precast concrete pile to cement soil and then from cement soil to soil around piles, is formed by inserting a precast concrete pile and the side resistance of a pile is effectively utilized under load. The main sources of high bearing capacity are the solidification effect of the cement soil, the pressing soil effect and the load transfer of the precast concrete pile. A composite pile has higher vertical bearing capacity and low cost. which are its advantage in application in soft ground.