沙土比对混凝土试件空蚀影响的试验研究

An experimental study of effect of sand to earth ratioon cavitation erosion of concrete specimens

在小型循环式水洞中试验研究了沙土比对混凝土试件空蚀影响的机理。首先,在循环式水洞内筒中配制11种沙土比(0%,10%,20%,30%,40%,50%,60%,70%,80%,90%,100%)试样,用红外测沙仪测定相同沙土比的3种不同含沙量(2,12,30 kg/m 3)的挟沙水样,用压力传感器和压力数据采集系统实时采集水洞文丘里工作段空化区和空蚀区的压力;然后,制作了水灰比为0.4、灰砂比为1.5,7 d龄期强度f cu,k=17.8 MPa的混凝土试件,将其安放在水洞文丘里工作段混凝土试件盒中进行4 h的空蚀试验。试验结果表明:沙土比的增大对空化和空蚀破坏均具有促进作用;消失空化数随沙土比的增加而增加,对空化发生具有抑制作用;相同沙土比时,混凝土试件的空蚀量随着含沙量的增加而增加。

The influencing mechanism of sand to earth ratio on the cavitation erosion of concrete specimens was experimentally studied in a small circulating water tunnel.Firstly,11 kinds of sand to earth ratio(0%,10%,20%,30%,40%,50%,60%,70%,80%,90%,and 100%)samples were prepared in the inner cylinder of the circulating water tunnel.Three kinds of sediment-laden water samples with different sediment concentrations(2,12,30 kg/m 3)of the same sand to earth ratio were measured with an infrared suspended solid analyzer.The pressure sensors and pressure data acquisition system were used to real-timely acquire the pressures in the cavitation and cavitation erosion zones of Venturi working section in the water tunnel.Secondly,concrete specimens with a water to cement ratio of 0.4,a cement to sand ratio of 1.5,and a compressive strength of 17.8 MPa at 7-day age were poured and placed in the concrete specimen box of the working section in the tunnel for a 4-hour cavitation erosion test.The experimental results show that the increase in sand to earth ratio can promote cavitation occurrence and cavitation erosion,the desinent cavitation number increases with the increase in sand to earth ratio,which can inhibit the cavitation occurrence,and for a sand to earth ratio,the cavitation erosion amount of concrete specimens increases with the increase in sediment concentration.