JPP桩不同组合水平承载性能模型试验研究

Model tests research on horizontal bearing behavior of JPP pile under different combinations

高喷插芯组合桩(简称JPP桩)是一种新型复合材料桩,实现了刚性桩的效果、柔性桩的成本,在基坑支护等工程中得到应用,但其水平承载性能的研究落后于工程实践。为了研究不同组合形式的JPP桩水平承载特性,利用自主研制的桩基模型试验加载系统进行了4种不同组合形式下JPP桩水平载荷试验,研究结果表明:分段组合II的水平承载能力最高,上组合与分段组合I相近,下组合的水平承载能力最低,表明越多的分段组合呈现出整体承受水平荷载的能力。桩身最大弯矩出现在距离桩顶以下3~4倍芯桩桩径处,该部位相对薄弱,易发生破坏。地面下一定深度范围内的土体特性将直接影响着桩的水平承载能力。

Jet grouting soil-cement-pile strengthened pile(JPP for short) is a new type pile which is composite of jet grouting pile and prestressed concrete core pile, and achieving the powerful effect of rigid pile and low cost of flexible pile. JPP pile is used in excavation protection and other engineering, but its research on horizontal bearing behavior falls behind the engineering practice. In order to study the horizontal bearing behaviors of different combinations JPP pile, horizontal load model tests are carried out by using the home-made model test pile loading system. The test results show that: sub-portfolio II carries maximum capacity, combined with the sub-portfolio I close, under combination carries the lowest capacity level, so the more sub-portfolio combination shows that the overall horizontal bearing capacity appears. Maximum moment of JPP pile occurs at the position of 3 to 4 times diameter under core pile top and this site is relatively weak and prone to damage. So we can conclude that the soil characteristics within a certain depth below the soil surface will have a direct impact on the horizontal bearing capacity.