高喷插芯组合桩承载力计算及影响因素分析

Bearing capacity calculation and influence factors analysis of jet grouting soil-cement-pile strengthened pile

高喷插芯组合桩(简称JPP桩)是一种新的组合桩型,该技术具有穿透力强、施工速度快以及经济效益好等优点。提出了承载力的一种简化计算公式,并结合工程实例验证了公式的合理性。结合静载荷试验,通过数值模拟分析了不同水泥土弹性模量、不同水泥土厚度和不同组合形式对JPP桩承载力的影响。模拟结果表明:水泥土无侧限抗压强度不宜小于1.5 MPa;水泥土厚度不宜小于100 mm,但也不宜大于芯桩的半径;固底组合可以有效提高承载力。这些分析结果对指导工程实践有一定的现实意义。

Jet grouting soil-cement-Pile strengthened Pile （JPP） is a new kind of composite pile, and its technology has more advantages, such as high penetration force, being constructed quickly, good economic performance, etc. A simplified calculation formula for bearing capacity is proposed; and its validity is verified by engineering example. Influencing factors of bearing capacity, such as different elastic moduli of soil-cement, different thicknesses of soil-cement, different combination form, etc. are analyzed by means of numerical simulation model based on field load test. The simulation results show that： unconfined compressive strength of soil-cement should be no less than 1.5 MPa; the thickness of soil-cement should be not only no less than 100mm but also be not more than the radius of core pile; base strengthening combination form of JPP pile is beneficial for improving bearing capacity. These results have some practical significance for guiding engineering practice.