吸沙式挡沙墙设计及防护效益分析

Design of sand-absorbing retaining wall and its protection benefit analysis

为了解决沙粒掩埋挡沙墙造成挡沙墙防护效果降低,文中基于k-ε湍流模型的RANS方法和多孔介质模型对不同参数的吸沙式挡沙墙进行数值模拟计算,并采用风洞试验验证文中所选湍流模型和网格划分策略的正确性。研究结果表明:风沙流经过挡沙墙会形成速度分区,分别为墙前减速区、墙后墙体结构导致的局部加速区、墙体正上方加速区、墙后涡流区以及恢复区。随着挡沙墙孔隙率减小,背风侧有效遮蔽区域越大,背风侧积沙位置离墙体越近,吸沙式挡沙墙的最优孔隙率在25%~35%,考虑到制造工艺,孔隙率选35%为宜;文中所设计挡沙墙的吸沙功能良好,吸沙量的大小正相关于孔隙率和来流风速;吸沙式挡沙墙周围的水平风速随高度增加逐渐从“U”型转变为“V”型分布,风速廓线在垂直方向上呈现倒“S”形分布。当风速一定时,有效防护距离随着挡沙墙高度的增加而增大,积沙范围增大;当高度一定时,积沙位置随着来流风速的增大逐渐向下风向转移。挡沙墙高度越高,承受的风压越大,工程造价上升,从防护距离和工程造价两方面考虑,四块挡沙板是吸沙式挡沙墙最合理阻沙高度。

In order to solve the problem that the sand particles always bury the sand retaining wall,and result in the reduction of the protective effect of the sand retaining wall,in this paper,the numerical simulation is carried out to analyze wind velocity changes around the sand-absorbing sand retaining wall with different parameters based on the RANS method in the k-ε turbulence model and the porous medium model,and the wind tunnel tests are used to verify the correctness of the turbulence model and the mesh delineation strategy selection.The results show that the wind-sand flow passing through the sand barrier wall will form five velocity zones:the deceleration zone in front of the wall,the partial acceleration zone behind the wall due to the wall structure,the acceleration zone directly above the wall,the vortex zone behind the wall,and the recovery zone.As the porosity of the wall decreases,the larger the effective sheltering area are on the leeward side,the closer the sand accumulation location is to the wall on the leeward side.The optimal porosity of the sand-absorbing retaining wall ranges from 25%to 35%,and considering the manufacturing process,it is advisable to choose a porosity of 35%.The sand-absorbing function of the sand retaining wall designed in this paper is good,and the magnitude of the sand-absorbing volume is positively correlated to the porosity and the incoming wind speed.The horizontal wind speed around the sand-absorbing retaining wall increases gradually from"U"-shaped to"V"-shaped distribution with the increase of height,and the wind speed contour shows an inverted"S"-shaped distribution in the vertical direction.When the wind speed is certain,the effective protection distance increases with the increase of the height of the sand retaining wall,and the range of sand accumulation increases.When the height is certain,the location of sand accumulation gradually shifts to the downwind direction with the increase of the incoming wind speed.The higher the sand retaining wall is,the greater the wind pressure is,and the higher the cost of the project is.So,considering the protection distance and the cost of the project,the wall with four sand barriers is the most reasonable design.