【作者】 陈文强；

【导师】 王建华；

【作者基本信息】 天津大学 ， 岩土工程， 2010， 硕士

【摘要】 随着深水石油开采的发展,张紧式吸力锚成为一个重要的深水海洋平台基础。由于这种基础不同于先前的重力式基础和桩基础,在设计理论上缺少统一的认识。因此评价张紧式吸力锚承载力对于设计此类吸力锚是十分重要的工作。为此本文针对如何评价张紧式吸力锚承载力问题开展了理论分析与模型试验研究。首先,依据塑性极限分析上限理论与极限平衡理论,对张紧式吸力锚极限承载力进行了理论分析,给出相应的计算方法,讨论如何选取计算参数,又针对计算方法特点,编制了相应的计算分析程序。其次,为了说明评价张紧式吸力锚承载力的塑性极限分析上限法与极限平衡法的可行性,进行了软粘土中张紧式吸力锚承载力模型试验。选取了两个直径试验锚,其长径比分别为4和6,进行了张紧角度为20°、30°、40°吸力锚承载力模型试验。分析了在不同张紧角度下吸力锚的破坏模式,以及张紧角度、长径比的变化对承载力的影响,得出吸力锚的破坏模式与吸力锚受荷角度密切相关,吸力锚的长径比和张紧角度的变化对承载力有很大影响,在相同的张紧角度并且长径比不同的情况下吸力锚最后发生破坏的模式基本没有发生变化。最后用塑性极限分析法和极限平衡分析法与模型试验结果进行了比较和分析。结果表明,这两种理论在评价张紧式吸力锚承载力方面是可行性。最后,对评价张紧式吸力锚极限承载力的塑性极限分析法和极限平衡分析法在破坏机理与破坏模式、参数选取、求解过程进行了分析和比较。结果表明,塑性极限分析上限法不能反映吸力锚破坏模式,但可以评价吸力锚受荷点不在最佳位置处的承载力,极限平衡分析法能反映吸力锚的破坏模式,但只可以评价吸力锚受荷点在最佳位置处的承载力。更多还原

【Abstract】 As exploration and production of oil resource progresses into deep waters, suction caissons with taut wires may be an important offshore foundation. However, because the work mechanism of this offshore foundation is different from the traditional gravity foundation and pile foundation, it lacks sophisticated design code at present. So it is important work to evaluate the capacity of suction caissons with taut wires. In this article, the studies are emphasized on the method of theoretical analysis and model tests of suction caisson in clay.First, the analysis of bearing capacity of suction caissons with taut wires is based on the theories of the upper bound limit analyses and the limiting equilibrium. The formulas of deriving and parametric study are described in this paper. Based on the characteristic of the two methods, I have compiled programs to calculate capacity of suction caissons with taut wires.Second, model tests of bearing capacity of suction caissons in soft clay were conducted in order to detaile the methods of upper bound limit analyses and limiting equilibrium in calculating reasonably capacity of suction caissons with taut wires. In model test, two suction caissons with slenderness ratio of 4, 6 and the load inclination degrees of 20°, 30°and 40°were used to study the failure mechanism under different load inclination degrees and capacity with different slenderness ratio, different load inclination degrees. We can obtain the capacity of suction caisson is affected by the changes of slenderness ratio and load inclination degrees. We obtained the failure models of suction caisson are affected by the inclination degrees and capacities are changed with different slenderness ratio and load inclination degrees. The failure models of suction caisson are same, when the caissons are with the same inclination degree and different slenderness ratio. The model tests of results are also compared with those from upper bound limit analyses and limiting equilibrium. We obtain that the method of upper bound limit analyses and limiting equilibrium are reasonable on calculating the capacity of suction caisson.At last, I compared the method of upper bound limit analyses and the method of limiting equilibrium on failure model, failure mechanism, parametric study and course of calculating. The method of upper bound limit analyses can not express the failure model, but the method of limiting equilibrium can express the failure model. The method of upper bound limit analyses can calculate the capacity of suction caissons in the case of rotation at failure. However the method of limiting equilibrium can only calculate the capacity of suction caissons with loading at the optimal loading point (no rotation at failure)更多还原