【摘要】 管道穿越山区河流河段的埋深设计是工程安全与经济造价的重要问题。当前河床冲刷计算方法众多,而不同计算方法的比较研究较少。本文以常用的一般冲刷、局部冲刷经验公式及非恒定数值模拟技术为基础,分析了某管道穿越河段冲刷特性。结果表明:非恒定流数值模拟方法能较全面反映穿越区域最大冲刷深度的演化过程,规范建议的一般冲刷64-1修正式与局部冲刷65-2式计算的最大冲刷程度与数值模拟结果较为吻合,而局部冲刷65-1式冲刷稍偏小,堤坝局部冲刷式计算偏差较大。更多还原

【Abstract】 It is quite common that a crossing pipeline was built in a hydraulic project in mountain river. The damages of pipeline engineering due to riverbed scouring at crossing zone occur frequently, which brings about serious aftermath. Riverbed scour mainly are controlled by water velocity and bed materials in river and accordingly empirical formulas considering velocity parameter were proposed and used in practice. However empirical formula to estimate the pipeline scouring has limitation and cannot be applied to all silario. Less work had been done regarding the comparison of different scour depth calculation. And noticeably, a disadvantage of these empirical formula is that they cannot describe the scour process of river bed, in particular, for the unsteady flood process with variable velocity. This paper took a crossing pipeline as an example, and then an unsteady 2 D flow-sediment numerical model with a Meiye-peter bedload transport rate was used to simulate the process of riverbed scour depth by a typical flood, and it demonstrated the changes of riverbed scour depth at the typical pipeline crossing zone by means of several empirical formulas stipulated by codes. The changes of velocity field and scour depth during the whole flood process at pipeline crossing zone were obtained through numerical simulation and the maximum scour depth was determined in the later stage of flood peak. The empirical scouring depth by several formulas could be calculated according to flow velocity and bed material diameter. The results showed that the calculating values of scour depth by the revised formula 64-1 and 65-2 were consistent well with that of the numerical simulation. However, there were median and larger errors by means of equation 65-1 and the dike-dam scour formula. The numerical simulation method introduced by this research can fully interpret the evolution process of scouring depth across a region, and has an important technical support for better understanding of pipeline scouring problem.更多还原