弯曲河道洪水冲刷重力式护管挡墙稳定性分析

STABILITY ANALYSIS OF GRAVITY PIPELINE PROTECTION RETAINING WALL SUBJECTED TO LOADS OF FLOOD IN RIVER BEND

护管挡墙受洪水冲刷破坏是沿河管道水工保护结构(护管挡墙)水毁的主要类型。针对目前工程中遇到的弯曲河道处重力式护管挡墙在洪水冲刷下的破坏现象,根据护管挡墙的结构特征和实际受力状态,综合考虑洪水冲刷、挡墙基底浮托力、渗透压力、墙底侧向淘蚀深度以及洪水水位骤降幅度等因素,导出护管挡墙受洪水冲刷稳定性系数和墙底侧向极限淘蚀宽度计算式,并探讨和分析各相关因素对挡墙稳定性的影响。结果表明:墙前受洪水离心作用使挡墙在洪水水位缓慢上涨期间向河内水平滑移失效的可能性降低,挡墙基底浮拖力、渗透压力和墙底侧向淘蚀等均使挡墙倾覆失效可能性增大,挡墙前后水位差大小与挡土墙抗倾覆能力呈非正比关系。文中所导公式及分析思路和方法能适用于沿河重力式护管挡墙稳定性分析,可为类似工程问题的设计与研究提供理论参考。

Gravity pipeline protection wall,as a main type of hydraulic protection projects,is likely to be destroyed by the rushing flood. In view of the present instability problems of gravity retaining wall subjected to loads of flood in river bend and according to the structure characteristics and the actual stress state of the pipeline protection retaining wall,the paper puts forward new formulas about safety factor of wall?s stability and the lateral scour limit depth under wall,in which the factors,such as the rush of flood,the buoyancy force,the seepage water pressure,the lateral widening depth under wall and the descent velocity of flood level,are considered. Based on the formulas,the effect of each factor on the stability of the retaining wall is analyzed. The results indicate that in the period of flood level rising,owing to the loads of flood in river bend,the wall shows a decreasing horizontal slide failure trend to the river. On the contrary,the buoyancy force,the seepage water pressure,lateral widening depth and the descent velocity of flood level make the retaining wall easy to overturn and there is a non-proportional relationship between the ability to resist overturning and the water level difference before and after the retaining wall. The formulas and analytical ideas and methods cannot only be adopted to the stability analysis of gravity retaining wall along the river,but also provide a theoretical reference for the similar engineering design and research.