*6.1. Effects of Wave Characteristics*

Basically, the wave-induced oscillatory liquefaction phenomenon of the porous seabed is highly relative to the water pressure propagating on it. As a consequence, the relation of the wave characteristics and the liquefaction depth in the vicinity of the tunnel is discussed in detail with respect to the wave period (*T*), wave height (*H*), and still water depth (*d*), separately. Table 2 lists the input data involving the wave variables and other parameters. Figure 14 characterizes the maximum liquefaction depth of the vertical section at *x* = 80 m which is on the left side of the tunnel in regard of the different wave conditions.


**Table 2.** Parameters used for in parametric study of wave characteristics.

It is well known that the wave height is in positive correlation to the value of the water pressure acting on the seabed precisely. Furthermore, the water pressure will affect the wave-induced pore water pressure in seabed deposits. As illustrated in Figure 14a, the maximum liquefaction depth grows deeper with an increase of the wave height, which shows the positive relationship between the wave height and the potential of liquefaction.

The wave period is another key wave parameter that influences the wave length directly, which will further affect the seabed transient liquefy process. In this study, the wave periods are from 8 to 10 s. From Figure 14b, the maximum liquefaction depth is progressively increase with the rise of wave periods. It can be concluded that the liquefaction degree is more intense in the case of a long wave period.

Lastly, the influence of still water depth is discussed. The water depth ranges from 30 to 40 m. Unlike wave height and period, the maximum oscillatory liquefaction depth decreases with the raising of still water depth, as shown in Figure 14c, which indicates that the wave-induced transient liquefaction is more likely to occur in the shallow water areas.

(**c**) Effects of water depths

**Figure 14.** The maximum liquefaction depth of seabed surrounding the tunnel with various (**a**) wave heights; (**b**) wave periods; (**c**) water depths.
