高喷插芯组合桩承载特性的影响因素分析

高喷插芯组合桩(简称JPP)是由高压旋喷桩和预应力混凝土芯桩构成的一种新型组合桩。依据提出的简化计算方法，对高喷插芯组合桩不同组合形式、水泥土厚度、水泥土弹性模量、刚度系数比等影响承载机理的主要因素进行分析，从不同影响因素对芯桩和水泥土轴力、第一、二界面的摩阻力的分布规律上进行研究。分析结果表明，实际工程施工中宜采用分段组合形式；水泥土厚度的增加对提高JPP桩承载力有很大的帮助但也不宜过厚，不宜大于芯桩的半径；水泥土弹性模量对竖向承载特性影响较小但水泥土强度要满足构造要求；刚度系数比不宜过小，不宜小于100，才能达到水泥土与芯桩变形协调，才能达到JPP桩提高承载力和减小沉降的目的。

Analysis of factors influencing bearing characteristics of jet grouting soil-cement-pile strengthened pile

Jet grouting soil-cement-pile strengthened pile(JPP pile) is a new kind of composite pile composed of high pressure jet grouting pile and prestressed core pile.JPP pile has different combination forms depending on soil conditions as well as the bearing capacity requirements.Based on the simplified calculation method presented,the main factors of JPP pile bearing mechanism,different combinations,different soil-cement thicknesses,different elastic moduli of soil-cement,and different stiffness coefficient ratios,are analyzed comparably.The axial force of core pile,soil-cement axial force,first interface resistance and second interface resistance,are discussed respectively.The research results show that:(1) The sub-combination JPP pile has better carrying effect and should be adopted in actual construction.(2) Increasing soil-cement thickness can effectively improve the bearing capacity of JPP pile,but should not be too thick,and should not be greater than the radius of the core pile.(3) Soil-cement elastic modulus has small effect on axial bearing properties of JPP,but should meet structural requirements.(4) The stiffness coefficients should not be too small and not less than 100,so as to achieve deformation coordination for soil-cement and core pile,and improve bearing capacity and reduce settlement of JPP pile.