随机波浪作用下海床动力响应及液化的理论分析

运用随机波浪理论,基于广义Biot动力固结理论,建立了能够考虑波浪荷载随机特性影响的计算海床动力响应及液化深度的解析数值模型,并从时域上进行求解分析.通过与传统线性规则波浪荷载作用下海床动力响应及液化深度的数值结果的对比分析,详细讨论了考虑波浪荷载的随机特性对于求解海床动力响应及液化深度的影响程度.结果表明,根据随机波浪理论计算得到的海床中的超孔隙水压力、水平有效应力、竖向有效应力、剪应力表现出较强的不规则性,其幅值沿着海床深度方向的变化趋势与根据线性规则波浪理论计算得到结果的变化趋势基本相同,但在同数量级上更大,同时计算得到的海床最大液化深度明显大于根据线性规则波浪理论计算得到的结果.因此,在海洋地基设计和自由场地安全评估时应该合理地考虑波浪荷载的随机特性.

Theoretical analysis of random wave-induced seabed response and liquefaction

Based on general Biot’s dynamic consolidation theory, a simple analytical model for simulating random wave-induced seabed response and liquefaction is established and solved together with stable and effective algorithm. The influence of random wave loading is investigated by comparing with the corresponding linear regular wave results with similar representative parameters. The results of comparison show that the distributions of amplitudes of pore wave pressure and effective stresses along depth in seabed are similar by using two different wave theories, but the dynamic response of seabed under random wave loading shows clear irregularity, and these amplitudes are greater than those under linear regular wave loading on the same quantity level. Compared with the liquefaction depth induced by linear regular wave loading, the result computed with random wave theory is much deeper. Therefore, the stochastic feature of random wave loading has to be duly taken into account in evaluation of safety and stability of various marine structures and offshore facilities.