桩顶预留净空或可压缩垫块的桩承式路堤沉降控制机理研究  

Mechanism of settlement control of piled raft with gap or compressible block at pile top for support of railway embankment

作　　者：郑刚[1] 纪颖波[1] 刘双菊[2] 荆志东[3] 

机构地区：[1]天津大学,天津300072 [2]天津城市建设学院,天津300380 [3]铁道第三勘察设计院集团有限公司,天津300142

出　　处：《土木工程学报》2009年第5期125-132,共8页China Civil Engineering Journal

基　　金：国家自然科学基金(50678115);天津市前沿基础研究计划重点项目(07JCZDJC09800)

摘　　要：基于作者已进行的试验研究并基于控制工后沉降的目的,在常规桩筏基础上,通过在桩顶设置预留净空或可压缩垫块,在路基处理中提出了利用部分路基填土荷载对土进行预压,然后再使桩主要承担荷载的设想,实现对桩身上部及桩端下土提前进行压密以减小工后沉降。在对京津城际轨道CFG桩地基处理进行有限元数值模拟分析的基础上,在桩顶与筏板之间引入净空,通过桩顶与筏板接触的常规桩筏基础的桩土相互作用及沉降发展的对比,研究预留净空桩(或可压缩垫块)基础在路基中应用时对工后沉降的控制机理。已进行的试验及数值分析结果表明,在桩顶与筏板接触上之前,土承担主要的荷载。桩顶预留一定高度的净空可以使桩身上部及桩端下土提前进行压密,减少桩端贯入量,并使部分土固结产生的沉降提前发生,并达到有效减小工后沉降的目的。Based on the experimental tests completed before, a concept of piled raft with gap or compressible block （PRGCB） at pile top is developed with conventional piled raft （CPR）. PRGCB is expected to reduce post-construction settlement by using part of the embankment as preloading to consolidate the soils surrounding and beneath the piles. FEM simulation of the CFG piled composite ground of the Jing-Jin high speed railway is carried out first, and then piled raft with gap between pile head and raft is analyzed. The interaction between pile and soil and the development of settlement of piled raft with and without gap between pile head and raft are comparatively studied. Experimental tests and numerical results show that with the gap, soil may carry most of the load applied before pile head and raft get in contact. As a result, soils surrounding the upper part of the piles and beneath pile tips may be compacted before the piles start to carry significant load, and thus post-construction settlement may be reduced.

关 键 词：预留净空 路堤 数值分析 工后沉降 

分 类 号：TU473.1[建筑科学—结构工程]