Semi-submersible offshore fish farm has been considered a step forward to the new aquaculture era. To make it more durable to the excitations caused by waves and current, this paper examines the nonlinear vertical accelerations and mooring loads of a semi-submersible offshore fish farm model under extreme conditions. The steady-state non-dimensional first- and second-order harmonic accelerations at five different positions along the frame and the mooring tensions are obtained via experimental measurements and numerical simulations. The results show that both the first- and second-order harmonic accelerations are independent of the positions on the model but dependent on the wave period. Under wave-only conditions, when $H\text{≤0.15m}$, there is little difference between the experimental measurements and the numerical predictions on the accelerations. When $H\text{≥0.20m}$, the increasement of acceleration amplitude is 0.5 %–4.1 % for experiment, while the value is 3.3 %–19.0 % for numerical simulation. Under combined waves and current conditions, compared with $H\text{≤0.15m}$, the second-order harmonic acceleration increases exponentially under larger wave height, and most of the experimental results are larger than the numerical predictions when the current velocity $V_2\text{=0.2m/s}$. The damping from the net enhances the nonlinearity of the second-order acceleration but it has little effect on the first-order. The current has a pronounced effect on the mooring tensions. When $T\text{=1.}39\text{s}$, the mean values of front mooring load at $V_2\text{=0.2m/s}$ are 6.4 times of that at $V_1\text{=0.1m/s}$ in maximum, but when the wave height reaches $H\text{=0.25}\text{m}$, the increase rate of mooring force gradually decreases. The free surface effect is also assessed in this paper.

半潜式近海养鱼场被认为是迈向新水产养殖时代的一步。为了使其更耐波浪和水流引起的激励，本文研究了极端条件下半潜式近海养鱼场模型的非线性垂直加速度和系泊载荷。沿框架的五个不同位置处的稳态无量纲一阶和二阶谐波加速度和系泊张力是通过实验测量和数值模拟获得的。结果表明，一阶和二阶谐波加速度均与模型上的位置无关，但与波周期有关。在仅波条件下，当$H\text{≤0.15m}$，实验测量值与加速度的数值预测之间几乎没有区别。什么时候$H\text{≥0.20m}$,实验时加速度幅值增加0.5%~4.1%,数值模拟为3.3%~19.0%。在组合波浪和水流条件下，与$H\text{≤0.15m}$，二阶谐波加速度在较大的波高下呈指数增加，并且大部分实验结果大于当前速度时的数值预测 ${伏}_2\text{=0.2m/s}$. 来自网络的阻尼增强了二阶加速度的非线性，但对一阶加速度影响不大。水流对系泊张力有显着影响。什么时候$吨\text{=1。}39\text{秒}$, 前系泊载荷的平均值 ${伏}_2\text{=0.2m/s}$ 是当时的 6.4 倍 ${伏}_1\text{=0.1m/s}$ 最大，但当波高达到 $H\text{=0.25}\text{米}$，系泊力的增加率逐渐减小。本文还评估了自由表面效应。