冲刷作用下海洋平台桩基的水平承载力分析及试验研究

发布时间：2018-05-23 17:02

本文选题：桩基 + 水平承载力　；参考：《武汉理工大学》2014年硕士论文

【摘要】：桩基工程中的水流冲刷作用是指在地表水或地下渗流水的冲刷作用下，基础中土颗粒逐渐被带走，土体被掏空的过程，是水流、易受侵蚀河床和桩基、墩台之间的相互作用。海洋平台在采油或作业过程中，桩腿插入泥中，，同时受到上部载荷、风、浪、流等环境荷载作用，桩腿很可能因为受力过大而发生各种形式的破坏，造成桩基边界条件的变化，从而引起桩体应力和位移的重新分布，对海洋平台的安全造成影响。同时土层覆盖厚度的降低以及其应力历史的变化对于桩基础承载性状也有着直接的影响，随着桩基承载力的下降将对桩腿及上部结构的安全性能产生潜在的威胁。由于对于冲刷前后桩基基础的荷载传递机理和承载性状变化的不了解，往往导致实际工程设计过程计算的不合理，造成工程上的不安全或不经济。因此有必要对冲刷前后桩基基础的荷载传递机理和承载性状的变化进行较深入系统的研究，以便采取相应的工程措施提高海洋平台的安全性。在实际工程中桩基础的水平静载试验是确定桩基础水平承载力最可靠的方法，本文通过不同冲刷深度下的桩基室内模型试验，获得在不同水平荷载下桩头水平位移以及沿桩身的应变，掌握冲刷作用对桩基水平承载性能的影响。在此基础上，采用FLAC3D软件模拟单桩在水平荷载作用下的承载性能，并将单桩水平静载试验结果与数值模拟结果以及现有规范计算出来的结果进行对比分析，依据模型试验结果修正数值模型相应参数，获得能考虑冲刷作用影响的单桩水平承载力计算模型。同时，根据试验结果探讨冲刷作用对土体抗力的影响，提出相应的P-Y曲线用于桩基水平承载力计算。最后采用已获得的数值模型对冲刷角、桩顶固定方式、和不同冲刷深度下单桩的水平承载力性状进行分析，得出一些对实际工程有益的结论。
[Abstract]:In pile foundation engineering, the water flow scour is the process of soil particles being gradually removed and soil being hollowed under the action of surface water or underground seepage water, which is the interaction between water flow, easily eroded river bed and pile foundation, pier and abutment. In the course of oil production or operation, the pile leg is inserted into the mud and subjected to the environmental loads such as upper load, wind, wave, current and so on. The pile leg may be destroyed in various forms because of the excessive force, resulting in the change of the boundary conditions of the pile foundation. Thus the stress and displacement of the pile are redistributed and the safety of the offshore platform is affected. At the same time, the decrease of soil cover thickness and the change of stress history have a direct effect on the bearing capacity of pile foundation. With the decrease of pile foundation bearing capacity, the safety performance of pile leg and superstructure will be threatened. The failure to understand the load transfer mechanism and load bearing behavior of pile foundation before and after scouring often leads to unreasonable calculation of actual engineering design process, resulting in unsafe or uneconomical engineering. Therefore, it is necessary to study the load transfer mechanism and the change of bearing behavior of pile foundation before and after scouring, so as to take corresponding engineering measures to improve the safety of offshore platform. In practical engineering, the water static load test of pile foundation is the most reliable method to determine the horizontal bearing capacity of pile foundation. In this paper, the indoor model test of pile foundation with different scour depth is carried out. The horizontal displacement of the pile head and the strain along the pile body are obtained under different horizontal loads, and the effect of scour on the horizontal bearing capacity of the pile foundation is grasped. On this basis, FLAC3D software is used to simulate the bearing capacity of single pile under horizontal load, and the results of water static load test of single pile are compared with the results of numerical simulation and the results calculated by existing codes. According to the model test results, the corresponding parameters of the numerical model are modified, and the calculation model of horizontal bearing capacity of single pile considering the effect of scour is obtained. At the same time, according to the test results, the effect of scour on soil resistance is discussed, and the corresponding P-Y curve is put forward to calculate the horizontal bearing capacity of pile foundation. Finally, the numerical model is used to analyze the horizontal bearing capacity of the pile, such as the scour angle, the fixed mode of the top of the pile, and the different scour depth, and some useful conclusions are obtained.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P742;TU473.1

【参考文献】