三维重构下的透水混凝土流场数值模拟研究

Numerical Simulation of Flow Field of Pervious Concrete under 3D Reconstruction

孔隙结构作为透水混凝土渗流重要组成部分,直接影响雨水的渗流效果,研究透水混凝土的内部流动情况,对于认识透水混凝土排水渗流机制具有重要理论意义.通过对20%孔隙度试件采用CT扫描技术获取分辨率为12.5μm的二维切片,结合Avizo软件阈值截断法进行三维重构,并且对其孔隙进行量化,通过测定不同水头下的混凝土内部流速与重构混凝土模型在CFD软件下的流速模拟对比.结果表明:模拟混凝土内部流速变化规律与试件连续测定渗透结果相符,并且由于内部存在不同的空喉结构导致内部流速在各结构上的流速具有明显的差别,甚至存在孔道转弯的结构导致流速为负值,同时也发现在混凝土中间部位孔道直径较大的流道流速出现最大值.透水混凝土的渗透排水效果与内部孔道结构息息相关,孔道直径越均匀渗透效果越好,孔道弯曲度越小渗透效果越好.

The pore structure is an important part of water flow in pervious concrete,which directly affects on rainfall infiltration.Studying the internal flow of pervious concrete has important theoretical significance for understanding the seepage mechanism of pervious concrete drainage.Two-dimensional sections with a resolution of 12.5μm were obtained by CT scanning technique on 20% porosity specimens,and three-dimensional reconstruction was performed by Avizo software using the threshold truncation method.The pores were measured under different water heads.The internal flow velocity of the concrete is compared with the flow rate simulation of the reconstructed concrete model under CFD software.The results show that the variation law of the internal flow velocity of the simulated concrete is consistent with the continuous measurement of permeability tests.The internal flow velocity has obvious difference in the flow velocity of each structure due to the different internal air-throat structure,even a negative velocity occurs in the turning of tunnel.It is also found that the maximum flow velocity occurs in the middle section of concrete with large pore radius.The effect of permeability and drainage of pervious concrete is closely related to the internal pore structure.The better the uniform diameter of the pipe is,the better the penetration of the channel is.