摘要
针对填海抛石层、动水区淤泥质复合地层及基坑空间受限等复杂地质条件,研究了DJP(潜孔冲击高压旋喷与旋扩工法组合)复合管桩施工工艺,并通过数值模拟和现场试验揭示了其荷载传递机理和综合应用效果。结果表明:DJP工艺可一次性完成填石层与风化岩层成孔成桩,通过水泥土外桩与预制管桩的协同作用,显著提升了嵌岩定位精度及水泥土在动水区的固结稳定性,同步增强了桩基抗水平承载力与防腐性能。研发的“水泥土复合管桩工法+地表超长送桩技术”采用模块化设计及六方头快速连接机构,实现了送桩器节段2 min内快速组装,突破了28 m超深送桩技术限制,有效规避了基坑开挖风险。芯桩(PHC管桩)承担主要竖向荷载(顶部占比66%),水泥土外桩通过侧摩阻力将荷载传递至桩周土体,形成“芯桩→水泥土→地层”3级传力路径,充分发挥摩擦桩特性,整体承载力提升了30%~40%。现场施工验证表明,管桩植入同心度偏差≤50 mm、垂直度偏差≤0.3%,关键参数均满足规范要求,技术可行性显著。研究成果不仅攻克了复杂地层预制桩施工的技术难题,还为类似工程提供了有益参考,具有重要的工程应用价值。
In response to complex geological conditions such as stone layers of reclamation,muddy composite strata in dynamic water zones,and confined foundation pit spaces,the construction technology of down-the-hole jet highpressure grouting(DJP)composite pipe piles was studied.The load transfer mechanism and comprehensive application effects of DJP were studied by numerical simulation and field tests.The results show that the hole formation and pile driving for both the reclamation stone layer and weathered rock layers can be completed in one operation by DJP process.That the synergistic effect of cement-soil external piles and precast pipe piles significantly improved the accuracy of rock-bonding positioning and the consolidation stability of cement-soil in dynamic water zones,and simultaneously enhanced the horizontal load-bearing capacity and corrosion resistance of the pile foundation.A technology of cement-soil composite pipe pile method+surface ultra-long delivery pile technology has been developed was applied to modular design and a hexagonal head quick-connect mechanism to rapid assemble driver segments within 2 min,overcoming the limitation of delivering piles deeper of 28 m,thus the risks of foundation pit excavation was avoided.The core pipe piles(PHC)bear the main vertical load(66%at the top),while the load was transferred to the the surrounding soil by lateral friction resistance for the cement-soil outer piles,forming a three-level force transmission path of core pile→cement-soil→stratum.The characteristics of friction piles was fully leveraged to increase overall load-bearing capacity by 30%~40%.On-site construction verification shows that the deviation in concentricity of pipe piles is≤50 mm,and the verticality is≤0.3%.All key parameters meet the standards,demonstrating significant technical feasibility.The research findings not only solve the technical challenges of prefabricated pile construction in complex strata but also provide valuable references for similar projects,with important application value.
作者
刘刚
孙泽
LIU Gang;SUN Ze(China Railway Seventh Bureau Group Third Engineering Company Limited,Xi'an 710032,China;Xi'an University of Architecture and Technology,Xi'an 710055,China)
出处
《市政技术》
2025年第8期45-53,共9页
Journal of Municipal Technology
关键词
填海淤泥地层
DJP复合管桩
潜孔冲击高压旋喷
超长送桩
荷载传递机理
silty strata of reclamation of
DJP composite pipe pile
down-the-hole jet high-pressure grouting(DJP)
extra-long delivery of piles
load transfer mechanism
