黏性土中分布式桩侧后压浆桩水平承载机制试验研究  

Experimental study on lateral bearing mechanism of distributed post-grouted pile in cohesive soil

作　　者：万志辉 戴国亮[2] 周峰[1] 徐艺飞[2] 高鲁超 胡涛 Wan Zhihui;Dai Guoliang;Zhou Feng;Xu Yifei;Gao Luchao;Hu Tao(Nanjing Tech University,Nanjing 211816,China;Southeast University,Nanjing 211189,China)

机构地区：[1]南京工业大学,江苏南京211816 [2]东南大学,江苏南京211189

出　　处：《土木工程学报》2023年第2期80-91,共12页China Civil Engineering Journal

基　　金：国家自然科学基金(52008100,51878160);江苏省基础研究计划(自然科学基金)(BK20200400)。

摘　　要：通过在黏性土中开展未压浆桩、环向点式后压浆桩、分布式后压浆桩的水平静载模型试验对比研究,探究分布式后压浆对黏性土中桩基水平承载性状的影响,基于开挖试验分析浆液在黏性土中的扩散情况,揭示分布式后压浆水平受荷桩-土相互作用机制。结果表明,桩侧后压浆可大幅度提升黏性土中桩基水平承载力,且分布式后压浆对提高黏性土中桩基水平承载能力优于环向点式后压浆;在相同荷载条件下分布式后压浆桩的桩侧土水平抗力系数的比例系数m值大于环向点式后压浆桩,且均大于规范推荐的未压浆桩m值的取值范围,并给出了软塑状黏土中桩侧后压浆钢管桩m值的推荐取值范围为3.1~3.7MN/m^(4);与环向点式后压浆相比,分布式后压浆可以更有效地增强上部桩周土体强度,改善桩身荷载传递规律及弯矩分布特征,且对控制桩身侧向位移与提高桩侧土抗力更为显著。此外,通过开挖试验与水平承载机制分析得出浆液在黏性土中主要以劈裂方式扩散,而分布式后压浆桩注入的浆液沿着桩身更为均匀地覆盖外侧表面,使其形成了更为稳定的桩-土相互作用体系,进而提高了桩基水平承载能力。The influence of distributed post grouting on the lateral bearing behavior of pile was investigated by comparing and analyzing the horizontal static load model test results of ungrouted pile,annular point post-grouted pile and distributed post-grouted pile in cohesive soil.Based on the excavation test,the diffusion of injected cement grout in cohesive soil was analyzed,and the interaction mechanism of distributed post-grouted pile-soil system subjected to lateral load was revealed.The results show that the lateral bearing capacity of pile in cohesive soil can be substantially increased by post grouting at the pile side,and the distributed post grouting is better than the annular point post grouting in improving the lateral bearing capacity of pile in cohesive soil.Under the same load conditions,the proportional coefficient m value of the lateral soil resistance coefficient of distributed post-grouted pile is greater than that of the annular point post-grouted pile,but both of them are larger than the value range of the m value of the ungrouted pile recommended by the code.The recommended value range of the m value of the post-side grouted steel pipe pile in soft clay is suggested to be between 3.1 and 3.7 MN·m^(4).Compared with the annular point post grouting,the distributed post grouting can more effectively enhance the soil strength around the upper part of the pile,improve the load transfer law and bending moment distribution characteristics of the pile shaft,and is more significant for controlling the lateral displacement of the pile shaft and improving the resistance of soil at the pile side.In addition,through the analysis of excavation test and horizontal load-bearing mechanism,it is concluded that the injected cement grout in cohesive soil is mainly spread by splitting,and the grout injected into the distributed post-grouted pile covers the lateral surface more evenly along the pileshaft,froming a more stable pile-soil interaction system,and thus improves the horizontal bearing capacity of the pile.The r

关 键 词：黏性土 桩侧后压浆桩 分布式后压浆 水平承载特性 桩-土体系相互作用 

分 类 号：TU473.1[建筑科学—结构工程]