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波浪作用下海床的稳定性直接影响着海洋构筑物的安全。目前在波土相互作用的研究中,虽然较多地涉及到对海床液化或剪切破坏的分析,但缺乏不同海床计算厚度和饱和度等条件下二者破坏特征的对比研究。本文基于波浪作用下海床应力的解析解,对砂土海床的剪切破坏和瞬态液化破坏特征进行了详细研究和对比。结果分析表明,对于波浪作用下不同饱和度的砂土海床,其剪切破坏深度随海床计算厚度的增加表现为3种变化模式,而其液化深度随海床计算厚度的增加则只表现为1种变化模式。相比非饱和砂土海床,饱和砂土海床计算厚度较小时才可能发生液化,且其液化深度最小,但相同条件下对应的剪切破坏深度却最大。波浪作用下砂土海床存在一个最不稳定厚度,其数值约为(0.2~0.3)倍波长,此时海床最易发生破坏,且破坏深度较大。波浪作用下砂土海床的剪切破坏在波峰和波谷处均可能发生,而瞬态液化只发生在波谷位置,且其液化深度位于剪切破坏深度范围内。
The stability of the sea floor under the influence of waves directly affects the safety of marine structures. At present, although the study of the interaction between the Earth and the soil is more involved in the analysis of the liquefaction or shear failure on the seafloor, there is a lack of comparative studies on the damage characteristics of the seafloor under different seafloor thickness and saturation calculation conditions. Based on the analytic solution of the seafloor stress under wave action, this paper studies and compares the shear failure and transient liquefaction of the sand bed. The results show that for the sandy seafloor with different saturation under wave action, the shear failure depth changes with the increase of seafloor thickness, and the liquefaction depth shows only with the increase of seafloor thickness A change of mode. Liquefaction is possible only when the calculated thickness of the saturated sandy seabed is smaller than that of the non-saturated sandy seabed, and the liquefaction depth is the smallest. However, the corresponding shear failure depth is the largest under the same conditions. Under the action of waves, there is one of the most unstable thickness of sand and seafloor, which is about 0.2 ~ 0.3 times of the wavelength. At this time, the seabed is most likely to be destroyed and the damage depth is greater. The shearing failure of sand and seafloor under wave action may occur at the crest and trough, but the transient liquefaction occurs only at trough and its liquefaction depth is within the range of shear failure depth.