钙质土上的海洋平台桩基安装阻力研究

Drivability Study for Installation of Offshore Pile Foundation in Calcareous Soil

钙质土具有特殊的性质,在进行桩基打桩作业时,会产生较大的阻力,施工较为困难。准确评估打桩阻力,选取合适的打桩锤是顺利完成海洋平台在钙质土上桩基安装的关键。位于沙特与科威特中立海域的油田土壤以钙质土为主,采用波动方程的方法对桩基进行了可打入分析,并与现场的实测打桩记录进行对比分析,发现实际锤击数均超过非土塞工况的上限锤击数,说明计算分析过程中低估了打桩阻力。利用桩基安装动力检测技术对打桩全程进行监测的结果显示,连续打桩过程中桩身的承载力达到设计承载力要求。根据CAPWAP得到的参数进行打桩分析,计算结果与实际锤击数吻合良好,且可供类似土质打桩可行性分析借鉴。

The calcareous soil's special nature troubles pile foundation installation much and evaluating the soil resistance to driving(SRD)for suitable hammer selection is key for completing offshore pile installation.Considering the fact that most soil layer beneath the oil field located in the neutral zone between Saudi Arabia and Kuwait is calcareous soil,the wave equation method was employed to analyze pile foundation's drivability and then having it compared with pile driving record actually measured to show that,the blow count recorded outperforms the upper limit of coring case,this means that the soil resistance is underestimated.Monitoring the pile by PDI's equipment in the pile-driving operation and the evaluating the pile bearing capacity during continuous driven by CAPWAP method showed that the designed capacity can be satisfied.The blow counts for pile driven analysis based on the parameter of CAPWAP analysis is similar to the recorded blows,so these parameter can be referred for drivability analysis in similar soil.