基于绕射理论的大尺度桥墩波浪力计算方法

Research of Calculation Method for Wave Forces Acting on Large-Scale Bridge Piers Based on Diffraction Theory

为拓展MacCamy绕射理论在大尺度桥墩波浪力计算方面的适用性,采用数值与解析相结合的方法对大尺度桥墩波浪力的计算模式进行了研究.首先基于数值方法研究了波浪作用下截面尺寸及截面形状对桥墩惯性力系数的影响;然后引入绕射系数对Morison方程进行修正,提出了能够适用于大尺度结构物波浪力计算的修正Morison方程.研究结果表明:相比圆截面桥墩而言,方形截面桥墩的惯性力系数值下降更快,大尺度效应更加明显;通过引入绕射系数修正后的Morison方程用于计算大尺度圆形桥墩波浪力后与数值解更接近;纵向尺寸取0.2倍波长时能较好的计算大尺度方型桥墩波浪力.

In order to make the MacCamy diffraction theory applicable to calculate the wave forces on large-scale bridge piers,a calculation method was analytically and numerically investigated. First,the effects of the cross-section dimension and cross-section shape on the bridge pier inertial force coefficients were numerically examined. Then,the diffraction coefficient was introduced into the Morison equation,making the classical Morison applicable to calculate the wave forces on large-scale structures. The results show that the initial force coefficient of the square cross-section pier decreases faster,and the large-scale effects are more obvious in square cross-section piers than in the circular cross-section piers. The analytical solutions obtained from the Morison equation with a diffraction coefficient are very close to the numerical solutions. When the longitudinal wavelength is 0.2 times the wavelength,the wave forces on the large-scale square piers calculated from the modified Morison equation agree well with the numerical results.