基于不同排距探讨双排桩组合结构的桩长及冠梁刚度优化设计  

Optimization Design of Pile Length and Crown Beam Lateral Stiffness of Double Row Pile Structure with Different Row Spacing

作　　者：尹华 YIN Hua(Shenzhen Geotechnical Investigation and Surveying Institute(Group)Co.,Ltd.Shenzhen 518028,China)

机构地区：[1]深圳市勘察测绘院(集团)有限公司,深圳518028

出　　处：《广东土木与建筑》2024年第11期11-15,81,共6页Guangdong Architecture Civil Engineering

摘　　要：双排桩支护结构因其整体刚度效应及桩土协同作用而使得其工作机理比较复杂。基于现行规范方法的双排桩模型,首先分析排距对双排桩抗倾覆稳定性计算,然后基于不同冠梁侧向刚度模型,即忽略冠梁刚度仅考虑双排桩门架结构侧向刚度、考虑冠梁刚度与门架结构刚度叠加以及考虑冠梁与连板(梁)组合结构刚度与门架结构刚度叠加,分别分析排距对双排桩桩顶位移的影响,最后结合实际工程监测数据分析可知:(1)增大双排桩间距可有效提高双排桩结构抗倾覆稳定性,同时充分考虑后排桩与土体之间摩檫力产生力矩,可有效减少双排桩嵌固长度;(2)冠梁侧向刚度取值对双排桩结构的变形较为敏感,因此在计算分析双排桩桩顶水平位移时,可考虑冠梁组合结构对冠梁侧向刚度的增大效果;(3)采用冠梁组合刚度时,双排桩组合冠梁结构不仅发生平面内弯矩变形还存在平面外的扭矩,因此组合结构冠梁侧向刚度需考虑一定折减系数,根据实际工程监测数据反分析得组合折减系数参考值为0.5~0.6。The mechanism of the double row pile support structure is relatively complex due to its overall stiffness effect and the interaction mechanism of pile-soil.Based on the current standard method,the double row pile model first analyzes the effect of row spacing on the anti-overturning stability calculation of double row piles.Then,the effects of row spacing on the top displacement of double row piles is analyzed separately based on different crown beam lateral stiffness models.The crown beam stiffness is ignored and only the lateral stiffness of the double row pile portal structure is analyzed.In addition,the combination of crown beam structure stiffness and portal structure stiffness,as well as the combination of crown beam and connecting plate(beam)structure and portal structure stiffness are considered in this model.Finally,combined with the field monitoring data of support for excavation,the following conclusions can be drawn:①The antioverturning stability of double row pile structures can be improved by increasing the spacing between double row piles.The embedded length of double row piles can be reduced by considering the moment generated by the frictional force between the rear row piles and the soil;②The lateral stiffness value of the crown beam is sensitive to the deformation of the double row pile structure.Therefore,when calculating and analyzing the horizontal displacement of the double row pile top,it is necessary to consider the effect of the crown beam combination structure on increasing the lateral stiffness of the crown beam;③When crown beam composite stiffness is used,the double row pile composite crown beam structure not only undergoes in-plane bending moment deformation but also has out of plane torque.Therefore,a certain reduction factor needs to be considered for the lateral stiffness of the composite structure crown beam.Based on the filed monitoring data,the reduction factor is back analyzed to be 0.5~0.6.

关 键 词：双排桩 组合冠梁 侧向刚度 惯性矩 抗倾覆稳定性 

分 类 号：TU443[建筑科学—岩土工程]