有限元法作为滩涂光伏阵列桩基设计计算方法的适用性研究

Study on the applicability of finite element method as the design calculation method of photovoltaic array pile foundation in mudflat

【目的】滩涂光伏电站的建设处于起步阶段,光伏阵列桩基在土建工程中占比很大,对投资有显著影响,目前承载力设计计算主要借鉴建筑行业规范,其适用性值得探讨。为改进滩涂光伏桩基设计计算方法,探索有限元方法对此的适用性,【方法】以既有滩涂光伏桩基设计方案为例,依据行业规范方法进行竖向、抗拔、水平承载工况复核计算,同时使用有限元超载法和强度折减法进行计算和分析。【结果】分析及对比结果显示:两类方法所依据的力学机理基本相同,计算得出的承载力规律一致,安全系数值接近,沉降值接近;竖向承载和抗拔工况,有限元法得出的安全系数略大于规范方法;水平承载工况,有限元法得出的安全系数略小于规范方法;对于滩涂光伏阵列桩基而言,竖向承载力安全系数最低,是承载力设计的控制工况;抗拔承载安全系数最高,远高于规范要求值,不是控制性工况;水平承载安全系数居中,有较充足的安全裕度,该工况容易满足要求。【结论】结果表明:有限元法计算能够生动展示桩基及支架的空间、过程和细部力学响应,有利于指导和改进设计,对滩涂光伏阵列桩基设计有良好的适用性;有限元法用于桩基承载力计算应优先使用超载法;滩涂光伏阵列桩基的承载特点和工作环境与建筑桩基不同,目前规范规定的竖向承载力安全系数偏保守,应适当放宽,对设计理论创新做出尝试,并合理地控制工程投资。

[Objective]The construction of photovoltaic power(PV)in mudflat is in the initial stage.PV array pile foundation accounts for a large proportion in civil engineering and has significant impact on investment.The design and calculation of its bearing capacity is mainly based on building standards now and the applicability needs to be discussed.In order to improve the design and calculation method of photovoltaic pile foundation,[Methods]the applicability of finite element method(FEM)is explored.Taking existing design schemes as examples,the vertical,uplift and horizontal bearing conditions are calculated and rechecked according to method of building standards,and the overload method and strength reduction method of FEM is used for comparison analysis.[Results]The analysis and comparison show that:the mechanical mechanisms of two method are basically same,the bearing capacity laws obtained are consistent,and values of safety factor and settlement calculated are close;The safety factors obtained by FEM for vertical bearing and uplift conditions are slightly higher than that obtained by building standard method;under horizontal loading condition,the safety factor obtained by the FEM is slightly smaller than standard method;the safety factor of vertical bearing condition of PV pile is the lowest,making it as the design control condition;the safety factor of uplift condition is the highest,and is far higher than standard requirement,making it not as a controlled condition;the horizontal bearing safety factor is in the middle,with sufficient safety margin,which is easy to meet the requirements of standard.[Conclusion]The results indicate that:the FEM can vividly display the space,process and detail mechanical response of pile and support,which is conducive to guiding and improving design,and has good applicability to the design of PV piles in mudflat;the overloading method of FEM should be prioritized for calculating the bearing capacity of pile foundation;for the bearing characteristics and working environment of array pile foundation of PV in mudflat are different from building,the safety factor of vertical bearing capacity specified in the current standard is conservative,and it should be appropriately relaxed for attempting design theory innovation and saving project investment.