湘黔铁路资水大桥冲刷稳定性计算分析

以湘黔铁路资水大桥为研究对象，就冲刷对铁路重力式实体桥墩稳定性的影响进行研究。采用弹性半空间地基模型分析基底冲刷淘空面积对桥墩稳定性的影响，并通过Matlab计算程序给出影响曲线表达式。通过曲线拟合出粒径和局部冲刷深度之间的关系。研究结果表明：基底冲刷淘空面积对桥墩稳定性各检算项目都有明确的影响，其中墩顶弹性水平位移和合力偏心矩较敏感，在基底冲刷淘空面积较小时率先达到最大容许值，此时二者对应的冲刷淘空面积占基底总面积百分比的最小值分别为14．3％和17．8％；当其他因素一定时，河床土粒径对局部冲刷深度有明显的影响，这种影响在粒径小于0．12m的范围内变化时最为强烈。分析结果反映出适当增大桥墩周围河床土粒径可以有效提高其冲刷稳定性。

Computational Analysis of the Scour Stability of Zishui Bridge on Xiang-Qian Railway

Taking Zishui railway bridge on Xiang-Qian railway as the research object, the effect of scour on the stability of solid gravity piers for railway bridges was studied. Elastic half-space foundation model was used to analyze the effect of the foundation scour area on pier stability. The expression of influence curve was found out by the program written by Matlab. The relationship between the grain diameter and the local scour depth was analyzed by curve fitting method. Study results show that the scour area of foundation base has definite impact on all check items of pier stability. Among which, the lateral displacement of pier top and the eccentricity of resultant force are more sensitive to such impact, and both take the lead in reaching the maximum permissible value when the scour area of foundation base is small. At this moment, the minimum values for the percentage between the corresponding scour area of them and the total area of foundation base are 14. 3 and 17.8 respectively. When other factors are constant, the grain diameter of the riverbed has obvious influence on the local scour depth. Such influence appears much more intense when the grain diameter is less than 0.12 m. Analysis results indicate that the scour stability of bridge can be improved efficiently by properly increasing the grain diameter of the riverbed around piers.