深水潜坝抛石加固现场试验及定位分析研究

Field Test and Positioning Analysis of Reinforcement of Deep Water Submerged Dam by Thrown Stones

潜坝是控制分汊型河道河势的常用工程之一,一般位于汊道口门处,该区域流态复杂,建成后潜坝及下游经常会遭到不同程度的冲刷导致不均匀沉陷,对其进行抛石加固是维持其功能的重要措施。抛石以往多用于护岸加固工程,传统的抛投落距公式适用于浅水区,对深水区抛石加固工程抛投落距研究不多,对抛投离散程度的研究更少,很难实现抛石准确定位。本文以长江下游和畅洲左汊口门潜坝加固工程为例,通过分析深水潜坝加固施工区水流流速的垂线分布规律,引入群体沉速的概念,推导出块石沉速、抛投落距和综合抛投离散参数公式,并用现场试验资料对其进行了验证和优化,确定了工程量扩大系数,实时实现施工准确定位及有效加固。该研究将传统的抛投落距公式延伸到深水区,同时对抛投离散程度进行了有益的探讨。研究基于现场试验成果,可为潜坝加固工程和其他类似工程的施工提供更可信的依据和参考。

Submerged dam is a commonly used structure to control the reaches of a braided river,and it is generally located at the entrance of the inlet.The flows in these areas are often complex.It may cause downstream scouring after the completion of the submerged dam and the consequent uneven subsidence.Riprap reinforcement is an important measure of maintaining the function of the submerged dam.The conventional riprap reinforcement project is used in the bank protection.The traditional stone-throwing distance formulas are generally applied to shallow water and related to the water surface velocity,water depth,and the weight of the stones.There is not much study on the riprap reinforcement project in deep water area,and the research on the stone scattering is much less.In this paper,the authors make the first attempt to conduct-field tests for investigating the throwing distance and the enlargement coefficient,and for optimizing the comprehensive scattering coefficient.These field tests were performed at the entrance of the left branch of Hechang-bar,which is located at the lower reach of the Yangtze River,China.Based on the vertical distribution of velocity,the formula of the fall velocity of stone in deep water area,the formula of the throwing distance and the formula of the comprehensive discrete coefficient are derived.These formulas are verified by field data.The research extends the traditional throwing distance formula to the deep water area,and discusses the dispersion degree of throwing stones.The results can provide reference for submerged dam reinforcement works or other similar construction projects.