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由多个分离基础组成的多基础系统是常用的海洋结构基础型式。基于破坏包络面理论,分析了砂土地基多基础系统的失效模式,建立了相应的承载力计算方法,并验证了计算方法的可行性。对比分析了单一基础和多基础系统不同荷载路径下的荷载安全系数,探讨了破坏包络面理论与分项系数法相结合的基础承载力计算方法。失效模式的分析表明,由于水平荷载的增大,四腿平台结构迎浪侧基础首先到达破坏包络线,其失效模式属于滑动失稳,但由于基础间的运动约束,其并不会出现真正的滑移破坏。随着水平荷载进一步地增大,迎浪侧基础承担的水平和竖向荷载不断减小,导致背浪侧基础受到不断增大的荷载。最终,背浪侧基础也到达破坏包络线,多基础系统失效。分析表明,荷载路径对基础的荷载安全系数有决定性的影响,计算基础的荷载安全系数需指明相应的荷载路径。鉴于破坏包络面的大小和形状取决于众多因素,基础设计时需采用特定工况下的破坏包络面进行承载力计算。
A multi-foundation system composed of multiple separation foundations is the most common type of marine structure. Based on the theory of failure envelope, the failure mode of the multi-foundation system of sandy soil foundation is analyzed, and the corresponding calculation method of the bearing capacity is established, and the feasibility of the calculation method is verified. The safety factor of load under different load paths of single foundation and multi-foundation system is contrasted and analyzed, and the calculation method of basic bearing capacity combined with failure envelope theory and sub-element coefficient method is discussed. The failure mode analysis shows that due to the increase of horizontal load, the foundation of the four-legged platform on the wave-front side first reaches the failure envelope and its failure mode belongs to the sliding instability, but it does not appear to be true due to the movement constraint between the foundation Slip damage. As the horizontal load further increases, the horizontal and vertical loads borne by the wave-front side continue to decrease, resulting in an ever-increasing load on the wave-front side. Ultimately, the backflush side of the foundation also reached the destruction envelope, and many of the basic systems failed. The analysis shows that the load path has a decisive influence on the load safety factor of the foundation, and the corresponding load path should be indicated when calculating the load safety factor. Since the size and shape of the failure envelope depend on a number of factors, the basis design requires the use of a failure envelope under specific conditions for carrying capacity calculations.