为探明上埋式涵洞基础埋置深度对地基承载力的影响,基于太沙基理论与顾安全公式,推导了适用于上埋式涵洞的地基承载力公式。利用有限元软件,分析了地基土的荷载-沉降(P-S)曲线随填土高度的变化规律,确定地基承载力容许值,将不同计算方法得出的地基承载力容许值与有限元计算值进行对比分析,同时分析了涵顶和基底土压力随填土高度的变化规律,探讨了不同计算方法下地基土的抗剪强度对地基承载力的影响,通过工程实例验证本文公式的合理性。研究结果表明:①涵洞侧填土增强了地基土的抗剪强度,使涵洞地基承载力得到提高,其提高程度受到涵洞侧填土附加土压力的影响;②随着地基土的内摩擦角和黏聚力的增加,地基承载力分别呈非线性和近似线性增长趋势,且内摩擦角对地基承载力的影响程度明显大于黏聚力;③本文公式计算的地基承载力与有限元计算值符合较好,且本文公式得出的地基承载力远远大于涵洞基底土压力,符合现场涵洞地基处于安全状态的实际情况。研究成果可为确定上埋式涵洞地基承载力提供理论支撑。
Abstract
In an attempt to identifying the influence of buried depth of culvert on the bearing capacity of foundation, a formula for the bearing capacity of buried culvert is deduced based on Terzaghi’s theory and Gu Anquan’s formula. Moreover, the allowable value of foundation’s bearing capacity is determined by analyzing the change of load-settlement curve against soil fill height using finite element approach. The allowable bearing capacity of foundation obtained by finite element method is compared with those by different calculation methods. In addition, the influence of shear strength of foundation soil on bearing capacity of foundation in different calculation methods is discussed. Finally, the rationality of the formula is verified by an engineering example. The research findings are as follows: (1) The side soil fill reinforces the shear strength of foundation soil and improves the bearing capacity of the culvert foundation. Such improvement is influenced by the additional soil pressure on the soil fill. (2)With the increase of internal friction angle, the bearing capacity of foundation increases nonlinearly, while with the increase of cohesion,bearing capacity increases in an approximately linear trend, and the impact of internal friction angle is much larger than that of cohesion. The influence of the internal friction angle on the bearing capacity of the foundation is significantly greater than that of the cohesive force.(3)The bearing capacity calculated by the formula proposed in this paper is in good agreement with the calculated value by finite element method, and also is much larger than the earth pressure at culvert base, which accords with the actual situation of the culvert foundationin a safe state.
关键词
上埋式涵洞 /
埋深效应 /
地基承载力 /
有限元分析 /
现场试验
Key words
buried culvert /
burial depth effect /
bearing capacity of foundation /
finite element analysis /
field test
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基金
广东省交通运输厅科技计划项目(科技-2013-02-010)
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