填海区内静力压桩的试验研究  

Field study on an instrumented pile jacked into reclaimed land

作　　者：沈文水 严中铂 俞峰[3] 应江远 

机构地区：[1]杭州余杭经济开发区管委会,杭州311100 [2]杭州远东房地产开发有限公司,杭州311100 [3]香港大学土木工程系,香港 [4]坤和建设集团有限公司,杭州310006

出　　处：《地基处理》2005年第4期32-37,共6页Journal of Ground Improvement

摘　　要：静压法施工已在东南沿海的软土地区得到广泛的应用。然而，在强度较高的土层中，如在砂性土中，鉴于压入难度，静压法一般不推荐使用。在香港的填海区域，广泛分布着砂性的海洋沉积土和风化程度不一的花岗岩。本文报导了一根长41．5m的静压H型钢桩在填海区内的压桩及载荷试验。试验中使用了大型的静力压桩机，最大压桩力达7375kN。该桩使用超载预压法压入，以单位时间内的沉降量作为收桩控制条件。沿桩长安装有30个应变计，以测定压桩及载荷试验过程中的桩身应力分布。同时，在离桩身不同距离处，装有三个水压计，以观测超静孔隙水压的变化情况。试验结果表明，当桩端通过水压计深度时，超静水压达到最大。超静水压一般在施工之后的半小时之内就几乎完全消散。按超载预压法施工的静压桩能够提供足够的设计承载力。与类似土层中的打入桩情况不同，静压桩的荷载传递表现为摩擦桩性状。Jack-piling method has been widely used for the soft ground in Southeastern China. Its application in stiff ground such as sandy soils is normally not recommended due to the difficulty in push-in. Sandy soils such as alluvium and weathered granite are distributed in the reclaimed land in Hong Kong. This paper reports pile-jacking and pile-load tests on a 41.Sin-long steel H-pile jacked into the reclaimed land. Large capacity jacking machine was used in the tests and the jacking load was up to 7375kN. The termination of jack-in was controlled by the condition of settlement rate, known as pre-creep method. The pile-load transfer was measured by thirty strain gauges installed along the shaft. Excess pore-water pressure was also detected by three piezometers installed at different distances to the pile. The test results showed that excess pore pressure reached the maximum when the pile tip approached to the monitored level, and it dissipated almost completely in 30min after installation. The pre-creep termination criterion took effect on providing adequate working capacity of pile. Unlike piles driven into similar soil deposits, the load-transfer characteristic of the jacked pile was floating-type.

关 键 词：静压桩 H型钢桩 压桩试验 静压法 软土地区 

分 类 号：TU67[建筑科学—建筑技术科学] TU476