碎石桩复合地基应力应变分析

来源期刊：中南大学学报(自然科学版)2002年第5期

论文作者：刘杰 张可能

文章页码：457 - 461

关键词：应力比;置换率;承载力;平衡状态

Key words：stress ratio; replacement ratio; bearing capacity; equilibrium state

摘    要：在考虑桩-土相互作用的基础上,根据桩-土侧向变形协调及竖向变形相等的条件,应用弹性理论导出了线弹性状态下桩体及桩周土的应力-应变关系,得出了桩体材料屈服时桩-土应力比的计算式;利用摩尔-库仑屈服准则导出了桩周土处于极限平衡状态时,桩体和桩周土竖向变形的表达式以及碎石桩极限承载力计算式;讨论了桩-土应力比与置换率及桩周土变形模量的关系.研究结果表明:用碎石桩加固软土地基,加固效果较好;但用碎石桩来加固土的变形模量大于8 MPa的地基,加固效果不明显.对于碎石桩加固的软土地基,应按控制沉降量设计法代替传统的控制承载力设计法进行设计计算.

Abstract: Based on the pile-soil interaction, equality of the vertical deformation and the harmony of the lateral deformation, relationship of the stress and the strain of the piles and the pile lateral soil are derived in the elastic theory under the linear elasticity. The formula of pile-soil stress ratio at the pile materials yielding is obtained. The formulas of the vertical deformation in the piles and the pile lateral soil, the ultimate bearing capacity of the single pile are derived in Mohr-Coulomb yielding condition at the ultimate equilibrium state. Relationships between the pile-soil stress ratio, the replacement ratio, and the pile lateral soil modulus of deformation are discussed. It is indicated that effectiveness reinforced by the gravel piles in the weak ground is obvious, but it isn′tobvious for the ground modulus of deformation to excess 8.0MPa, and reinforced effectiveness is finite.It is also shown that the traditional design method of controllingb earing capacity should be replaced by the design method of controlling settlement to the weak ground reinforced by the gravel pile.