准确预测桩基周围抛石防护实施后的冲刷深度不仅为桩基维护工程设计提供抛石量的计算依据，而且为桩基抛石防护设计的安全性提供检验手段。通过水槽试验，探讨了桩墩周围抛石层最大冲刷深度随桩径、抛石粒径、水深、来流流速等要素的变化特征。试验结果表明，抛石层厚度应大于沙波高度，抛石范围应大于5倍桩径，以免抛石层的稳定性受沙波影响；在此条件下，抛石粒径越大，防护效果越好，桩径越大，冲刷深度越大。最后，基于试验结果提出了抛石防护下的最终冲刷深度计算公式，为桩基抛石防护的工程设计提供计算依据。

Riprap protection is regarded as one of the most widely used methods for erosion protection of hydraulic foundations such as bridge piers in water. To accurately predict the scouring depth at the pile foundation after the implementation of riprap protection not only provides a calculation tool for the riprap amount for pile foundation maintenance engineering design， but also provides a means for the safety assessment of pile foundation for riprap protection design. This article experimentally explores the variation characteristics of the maximum scouring depth in the riprap layer at the pile with factors such as pile diameter， riprap particle size， flow depth， and approach flow velocity， respectively. The flume experiments show that in order to improve the stability of the riprap layer， the thickness of the riprap layer should beat least as large as the bedform height， and the range of the riprap layer should be at least larger than 5 times the pile diameter to avoid bedform destroy. Under these conditions， the larger the size of the riprap， the better the protective effect would be， and the larger the pile diameter， the greater the scour depth would be. Finally， a formula for calculating the maximum scouring depth after riprap protection is proposed， which would provide reference for future engineering design for riprap protection.