海管浮重对砂床局部冲刷扩展的影响研究

项目名称： 海管浮重对砂床局部冲刷扩展的影响研究

项目编号： No.11302235

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 数理科学和化学

项目作者： 李磊

作者单位： 中国科学院力学研究所

项目金额： 25万元

中文摘要： 本项目拟针对海管-砂床局部冲刷过程中海管浮重载荷的影响规律这一关键问题，以冲刷实验中砂床的孔压分布演化及统计特征为切入点，探讨海管浮重对砂粒临界起动及冲刷扩展形态的影响。具体而言，本项目拟通过分布式孔压动态测量系统与高速PIV系统，对海管浮重作用下的砂床孔隙水压分布在冲刷过程中的演化趋势以及冲刷平衡时床面附近的流场进行精细测量；并以测量数据为基础，结合土力学理论方法得到的砂床内应力分布状况，讨论砂粒间的相互作用力方式，并讨论冲刷坑床面上砂粒临界起动的条件变化，结合实测的床面形态与水流切应力，给出海管浮重作用下的砂粒临界起动判据修正形式，最终提供预测海管浮重作用下的砂床局部冲刷扩展预测模型。为此类研究的发展和应用提供基础数据与有效思路。

中文关键词： 海底管道；泥沙起动；冲刷平衡；扩展坡度；扩展跨度

英文摘要： This proposal is focusing on the influncing law of pipeline submerged-weight in pipeline-sandy bed local scour procedure. The distribution history and statistical characteristics of pore water pressure in sandy bed is studied by experiment, and the influnce of pipeline submerged-weight on sand critical break and propagation configuration. To be specific, we are going to carry out a series of experiments, in which the pore water pressure history and the flow field near equilibrium scour bed are measured using dynamic distributed pore water pressure gage and high speed PIV respectively. Based on the data measured and combined with the stress distribution in sandy bed from soil mechanics, the interaction pattern within sandy bed is conducted. Then the condition of sand critical break is drawn out. In this way, combined with the measured scour hole configuration and flow shear stress, the modified formula of sand critical break under the load of pipeline submerged-weight could be given out. Ultimately, a prediction model for sandy bed local scour propagation under pipeline submerged-weight could be provided for practical usages. When the mechanism of the pipeline influncing the scour propagation has been further understood, the discussion on maximum length or slope of scour hole could runs further. In summary, this

英文关键词： submarine pipeline；scour onset；scour balance；propagation slope；propagation span distance