基于离心模型试验的悬臂式排桩力学特性
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摘要
为研究悬臂式支护结构在基坑开挖过程中的力学特征,结合某大型二线船闸深基坑工程,通过采用离心模型试验分析排桩在基坑开挖过程中的位移和土压力的变化规律,并借助数值模拟的方法进行验证及分析开挖过程中桩身的弯矩及剪力的分布及变化情况。结果表明:桩基挡土侧土压力在固结时期接近静止土压力状态,二级基坑开挖时接近主动土压力理论值,并且在基坑开挖过程中,土压力逐渐减小;受基坑开挖的影响,基坑侧土体因支护桩挤压而发生破坏,土压力重新分布,且相同深度处被动区土压力大于主动区土压力;桩身弯矩因土压力差的影响而呈"C"形分布,剪力呈"S"形分布,最大弯矩及剪力突变位置都随基坑开挖而向桩身下移。
In order to study the mechanical characteristics of the cantilever retaining structure in the excavation process of the foundation pit,we combine with the deep foundation pit engineering of a large second ship lock,analyze the displacement of the row pile and the variation law of earth pressure during the excavation process by the centrifugal model test, and apply the numerical simulation method to verify and analyze the distribution and change of bending moment and shear force of the pile body during excavation. The results show that the earth pressure on the retaining side of the pile foundation is close to the static earth pressure state in the consolidation period, the theoretical value of the active earth pressure is close to the second foundation pit excavation,and the earth pressure is gradually reduced during the foundation pit excavation process. Due to the influence of foundation pit excavation,the soil on the side of the foundation pit is destroyed by the support pile extrusion,the earth pressure is redistributed,and the earth pressure in the passive zone at the same depth is greater than the earth pressure in the active zone, the bending moment of the pile body is due to the earth pressure. The "C"shape distribution law is presented by the influence of the difference,and the shear force exhibits the "S"shape distribution law. The maximum bending moment and the shear force abrupt position are moved downward toward the pile body as the foundation pit is excavated.
In order to study the mechanical characteristics of the cantilever retaining structure in the excavation process of the foundation pit,we combine with the deep foundation pit engineering of a large second ship lock,analyze the displacement of the row pile and the variation law of earth pressure during the excavation process by the centrifugal model test, and apply the numerical simulation method to verify and analyze the distribution and change of bending moment and shear force of the pile body during excavation. The results show that the earth pressure on the retaining side of the pile foundation is close to the static earth pressure state in the consolidation period, the theoretical value of the active earth pressure is close to the second foundation pit excavation,and the earth pressure is gradually reduced during the foundation pit excavation process. Due to the influence of foundation pit excavation,the soil on the side of the foundation pit is destroyed by the support pile extrusion,the earth pressure is redistributed,and the earth pressure in the passive zone at the same depth is greater than the earth pressure in the active zone, the bending moment of the pile body is due to the earth pressure. The "C"shape distribution law is presented by the influence of the difference,and the shear force exhibits the "S"shape distribution law. The maximum bending moment and the shear force abrupt position are moved downward toward the pile body as the foundation pit is excavated.
引文
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[7]American Society for Testing Materials.Standard practice for making and curing concrete test specimens in the laboratory:ASTM C192/C192M-2012[S].West Conshohocken:ASTM,2012.
[2]董洁,李建军,秦伟华,等.悬臂桩基坑支护数值分析[J].绿色科技,2015(12):273-275.
[3]黄雪峰,张蓓,覃小华,等.悬臂式围护桩受力性状与土压力试验研究[J].岩土力学,2015,36(2):340-346+422.
[4]许会涛,张仲杰,王蕊芳.悬臂式支护桩内力及土压力的试验研究[J].煤炭工程,2007(1):86-88.
[5]朱彦鹏,王秀丽,于劲,等.悬臂式支护桩内力的试验研究[J].岩土工程学报,1999(2):101-104.
[6]赵明华,李文,张锐.考虑桩-土相互作用的悬臂式排桩内力计算方法研究[J].湖南大学学报(自然科学版),2014,41(1):1-7.
[7]American Society for Testing Materials.Standard practice for making and curing concrete test specimens in the laboratory:ASTM C192/C192M-2012[S].West Conshohocken:ASTM,2012.