Sediment incipient motion is a fundamental issue in sediment transport theory and engineering practice. Whilst Shields curve often is used to determine the threshold of sediment movement under unidirectional current conditions, it is unclear whether it can be directly applied for the wave or combined wave-current conditions. The study developed adaptive criterion curves describing incipient motion of sediment under wave and current conditions based on the flow pattern around the sediment particles. Firstly, the flow pattern law for fixed particles was recognized based on the friction law under various dynamic conditions (wave, current, and their combinations), and the flow pattern demarcations for incipient sediment motion were obtained with the threshold conditions for sediment movement under various dynamic conditions combined. Secondly, the exact shape of the Shields curve in each flow regime was derived under the current condition. By combining the flow pattern demarcations for incipient sediment motion under the wave condition, the criterion curve under the wave condition was derived. By combining the flow pattern demarcations for incipient sediment motion under the combined current-wave condition, the criterion curve for sediment incipient motion under the combined current-wave condition was derived. The results indicated that the flow pattern around incipient particles includes laminar, laminar-rough turbulent transition, and rough turbulent regimes. The criterion curves for sediment incipient motion under various dynamic conditions stayed the same in the laminar and rough turbulent regimes, but different in the transition regime. Depending on the relative strengths of the currents and waves, the shape of the criterion curve under the combined current-wave condition transitions adaptively between the criterion curve under the current condition and the criterion curve under the wave conditions.

泥沙初始运动是泥沙输运理论和工程实践中的一个基本问题。虽然 Shields 曲线常用于确定单向流条件下沉积物运动的阈值，但尚不清楚它是否可以直接应用于波浪或组合波流条件。该研究根据沉积物颗粒周围的流动模式，开发了描述波浪和水流条件下沉积物初始运动的自适应标准曲线。首先，基于摩擦定律在各种动力条件下（波浪、电流及其组合）识别固定颗粒的流型规律，并在各种动态条件下以泥沙运动的阈值条件获得初期泥沙运动的流型分界。动态条件相结合。第二，在当前条件下推导出每个流态中盾牌曲线的确切形状。结合波浪条件下初始沉积物运动的流型划分，推导出波浪条件下的判据曲线。结合流波组合条件下沉积物初期运动的流型划分，推导出流波组合条件下沉积物初期运动的判据曲线。结果表明，初始粒子周围的流动模式包括层流、层流-粗糙湍流过渡和粗糙湍流状态。不同动力条件下沉积物初始运动的判据曲线在层流和粗糙湍流状态下保持不变，但在过渡状态下不同。