首页|K0≠1时条形基础地基临塑荷载公式

K0≠1时条形基础地基临塑荷载公式

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目前土力学教材中给出的条形基础临塑荷载公式都是假定侧压力系数K0=1,其计算结果偏大.已有文献在推导K0≠1的临塑荷载公式时,由于近似计算或假定不合理,导致给出的公式不准确.本文首先沿基底附加应力产生的地基中主应力方向建立局部直角坐标系,得到K0≠1时地基中一点的应力表达式;再通过误差分析,确定出主应力开平方近似计算式中系数的合理取值;然后根据塑性区开展深度为0,得到局部坐标系与竖向的夹角;最后将应力表达式代入Coulomb准则,利用开平方近似计算式、三角函数级数展开式,通过求导得到临塑荷载公式.算例表明:对于通常情况下的条形基础,K0≠1时地基土自重应力引起的主应力轴偏转角度较小,采用土力学教材中公式计算临塑荷载误差在10%以内,采用本文提出的公式计算临塑荷载,可以保证误差小于1.0%.
The Formula of Subgrade's Approaching Plasticity Load for Strip Footings with K0≠1
At present,the formula of subgrade's approaching plasticity load for strip footings given in the textbook of soil mechanics assumes that the coefficient of lateral pressure K0=1,and the calculated result is some larger.During the deduction of the formulas with K0≠1 in the existing literatures,unreasonable approximating calculation or assume had been adopted and the formulas were inaccurate.At first,the local rectangular coordinate system is established along the principal stress direction in the subgrade caused by the additional stress under the strip footing,and the stress expres-sions of a point in the subgrade are obtained with K0≠1;Through error analysis,the reasonable value of the coefficients are determined in the approximate calculation formula for square root;Then,the angle between the local coordinate system and the vertical is obtained based on the developing depth of the plastic zone is zero;Finally,the stress expres-sion are substituted into the Coulomb criterion,and the formula of subgrade's approaching plasticity load is obtained through derivation with the help of the approximate calculation formula for square root and the polar expansion of trigo-nometric function.The calculation example shows that for the usually strip foundations,the deflection angle of the prin-cipal stress axis caused by the self weight stress of the foundation soil is very small when K0≠1,the error of approach-ing plasticity load calculated by the formula in the soil mechanics textbook is less than 10%,and an error of less than 1.0%can be guaranted when it is calculated by the formula proposed in this paper.

approaching plasticity loadstrip footingcoefficient of lateral pressureapproximate calculation formula for square rootprincipal stress

许年春、卢锦、戴坤鹏、郑瑞

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重庆科技大学 建筑工程学院,重庆 401331

重庆市勘测院,重庆 401120

临塑荷载 条形基础 侧压力系数 开平方近似计算式 主应力

重庆市基础与前沿研究计划项目重庆科技大学研究生科技创新计划项目重庆科技大学研究生科技创新计划项目

cstc2020jcyjA30002YKJCX2120662YKJCX2120655

2024

10.13774/j.cnki.kjtb.2024.02.013

科技通报
浙江省科学技术协会

科技通报

CSTPCDCHSSCD
影响因子：0.457
ISSN：1001-7119
年,卷(期)：2024.40(2)
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