波浪作用下海床瞬态剪切破坏深度的计算分析

Computing Analysis on Transient Shear Strength Failure Depth of Seabed from Waves

鉴于弹性本构模型的简便性,目前波浪作用下海床瞬态剪切破坏深度的计算一般都是基于海床的多孔弹性介质模型,这种方法不能考虑塑性单元不平衡应力的重分配,而如果将海床视为多孔理想弹塑性介质进行波浪作用下的瞬态响应分析,则可以克服上述缺陷。为此,以波浪作用下砂质、粉砂质海床瞬态响应模型为例,基于Mohr-Coulomb屈服准则,对不同海床计算参数条件下上述2种计算方法的结果进行了对比分析。结果表明,将海床视为多孔理想弹塑性介质时海床瞬态剪切破坏深度大于等于海床为多孔弹性介质时的计算结果;随着海床计算参数的变化,2种方法计算结果的变化趋势较为一致,且在砂质、粉砂质海床常见计算参数范围内,2种方法计算结果的差值在一个相对固定的范围内变化。

Most of the analysis on wave induced transient shear strength failure depth of seabed is performed regarding the seabed as a porous elastic medium for its simplicity. This approach cannot consider transfer of the unbalanced stresses of the yield elements. This problem can be solved if the seabed is treated as a porous perfectly elasto-plastic medium. In order to have a full investigation on the computation of the wave induced transient shear strength failure depth of the seabed, taking the sandy and silty-sandy marine soil as an example, using the Mohr-Coulomb yield criterion, the transient shear strength failure depth of the seabed is analyzed for various seabed parameters by the two methods mentioned above. Results of the two methods have shown that the transient shear strength failure depth from the porous perfectly elasto-plastic medium is greater than or equal to the corresponding results from the porous elastic seabed. Changing the seabed parameters, results of the two methods vary with a consistent trend. For the general parameters of the sand and silty-sand, difference of the two method results changes in a relatively steady range.