建筑基坑多支点支护桩支护特征参数研究
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摘要
施加预应力的多支点支护桩比悬臂桩和单支点支护桩受力更为复杂,难以通过强度和构造要求较为准确地确定其最佳嵌固值,这会导致实际设计中嵌固值易出现过大倾向.结合压缩模量与割线刚度之间经验关系,确定硬化土体(HS)模型部分参数,进而从支锚力、径距比、土层条件等方面,分析总结多支点支护桩嵌固值等支护特征参数的变化规律,并得到一种判断多支点支护桩近似最佳嵌固值的方法,最后用工程实例予以验证.研究结果表明,嵌固值变化时,若支护桩内外侧最大水平位移值的变化趋稳,则可判别支护桩处于近似最佳支锚力作用;在近似最佳支锚力作用下,支护桩最佳径距比及最佳嵌固比一般约为定值.
The stress of the prestressed mutil- fulcrum supporting piles is more complex than that of cantilever piles and single- fulcrum supporting piles,so it is difficult to accurately determine the optimum embedded depth through strength and structural requirements. To solve this problem,empirical relation between modulus of compression and secant stiffness is used to establish a plane HS( Hardening Soil) model. The change rules of characteristic parameters including embedded depth of the retaining piles from the retaining anchor,span ratio,the soil conditions etc are analyzed. A method to judge approximate optimal embedded depth is proposed thereafter.It is shown by analytic results that under approximate optimal retaining anchor conditions,when the embedded depth changes,the interior and outboard horizontal displacements of the mutil- fulcrum supporting piles are steady,which may indicate that the pile is forced by the approximate optimal retaining anchor. For approximate optimal retaining anchors,the best span ratio of retaining pile and approximate optimal embedded ratio of retaining pile both are generally near fixed values.
The stress of the prestressed mutil- fulcrum supporting piles is more complex than that of cantilever piles and single- fulcrum supporting piles,so it is difficult to accurately determine the optimum embedded depth through strength and structural requirements. To solve this problem,empirical relation between modulus of compression and secant stiffness is used to establish a plane HS( Hardening Soil) model. The change rules of characteristic parameters including embedded depth of the retaining piles from the retaining anchor,span ratio,the soil conditions etc are analyzed. A method to judge approximate optimal embedded depth is proposed thereafter.It is shown by analytic results that under approximate optimal retaining anchor conditions,when the embedded depth changes,the interior and outboard horizontal displacements of the mutil- fulcrum supporting piles are steady,which may indicate that the pile is forced by the approximate optimal retaining anchor. For approximate optimal retaining anchors,the best span ratio of retaining pile and approximate optimal embedded ratio of retaining pile both are generally near fixed values.
引文
[1]中华人民共和国住房建设和城乡建设部.JGJ120—2012建筑基坑支护技术规程[S].北京:中国建筑工业出版社,2012:20-25.
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[3]李顺群,郑刚,王英红.反压土对悬臂式支护结构嵌固深度的影响研究[J].岩土力学,2011,(11)32:3427-3436.
[4]周汉香,莫海鸿.悬臂支护结构嵌固深度的可靠性优化分析[J].华南理工大学学报:自然科学版,2000,28(4):109-115.
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[7]王卫东,王浩然,徐中华.基坑开挖数值分析中的土体硬化模型参数的试验研究[J].岩土力学,2012,33(8):2283-2289.
[8]宋广,宋二祥.基坑开挖数值模拟中土体本构模型的选取[J].工程学报,2014,31(5):86-94.
[9]刘国彬,王卫东.基坑工程手册[M].2版.北京:中国建筑工业出版社,2009:147-158.
[10]中国土木工程学会土力学及岩土工程分会.深基坑支护技术指南[M].北京:中国建筑工业出版社,2012:90-125.
[2]傅志峰,吴晓云,刘芳,等.支护结构嵌固深度的计算分析[J].土工基础,2011,25(2):72-75.
[3]李顺群,郑刚,王英红.反压土对悬臂式支护结构嵌固深度的影响研究[J].岩土力学,2011,(11)32:3427-3436.
[4]周汉香,莫海鸿.悬臂支护结构嵌固深度的可靠性优化分析[J].华南理工大学学报:自然科学版,2000,28(4):109-115.
[5]师庭飞.昆明地区排桩式支护结构嵌固深度研究[D].昆明:昆明理工大学,2013.
[6]刘畅.考虑土体不同强度与变形参数及基坑支护空间影响的基坑支护变形与内力研究[D].天津:天津大学,2008.
[7]王卫东,王浩然,徐中华.基坑开挖数值分析中的土体硬化模型参数的试验研究[J].岩土力学,2012,33(8):2283-2289.
[8]宋广,宋二祥.基坑开挖数值模拟中土体本构模型的选取[J].工程学报,2014,31(5):86-94.
[9]刘国彬,王卫东.基坑工程手册[M].2版.北京:中国建筑工业出版社,2009:147-158.
[10]中国土木工程学会土力学及岩土工程分会.深基坑支护技术指南[M].北京:中国建筑工业出版社,2012:90-125.