桥梁矩形基础承载特性的深度与宽度效应研究

Study on Depth and Width Effects of Bearing Capacity Characteristics of Bridge Rectangular Foundation

桥梁矩形基础承载特性的深度、宽度效应问题尚未完全解决,以均质砂土地基为例,对桥梁矩形基础沉降、极限承载力的深度与宽度效应开展了数值计算,研究了规范提供的经验修正公式计算结果的合理性,讨论了考虑沉降控制的容许承载力的合理确定方法。计算结果表明:在上部荷载不变的情况下,基础沉降随着基础相对埋深和基础宽度增加非线性减小;极限承载力随着基础相对埋深和基础宽度增加近似线性增加;地基土的破坏模式与基础埋深有关,埋深越小越趋向于出现整体破坏,埋深越大越趋向于出现局部破坏;当基础宽度和基础相对埋深较小时,极限承载力是基础承载能力的控制性因素,当基础宽度和基础相对埋深较大时,沉降是基础承载能力的控制性因素;当基础宽度和基础相对埋深较小时规范取值偏于保守,而当基础宽度和基础相对埋深较大时规范取值偏于危险。

The problems of the depth and width effects of bearing capacity characteristics of bridge rectangular foundation have not been completely solved.Using the homogeneous sandy soil foundation as an example,the numerical calculation was carried out to study the settlement of bridge rectangular foundation and the depth and width effects of ultimate bearing capacity.On this basis,the rationality of the calculation results of empirical correction formula provided by specif ication was studied,the method to determine the allowable bearing capacity considering settlement control was discussed.The results show that when the upper load is constant,the foundation settlement decreases nonlinearly with the increase of relative depth and width of foundation.The ultimate bearing capacity increases linearly with the increase of relative depth and width of the foundation.The failure mode of the foundation soil is related to the depth of the foundation.The smaller the depth,the more tend to appear for the overall failure,the greater the depth,the more tend to appear local failure.When the width and relative depth are small,the ultimate bearing capacity is controlling factor of the bearing capacity of the foundation.When the width and relative depth are large,the settlement is controlling factor of the bearing capacity of the foundation.When the width and relative depth are small,the specif ication value tends to be conservative.When the width and relative depth are large,the specif ication value tends to be dangerous.