砂雨法制备砂土地基模型控制要素试验研究

为掌握砂雨法制备砂土地基模型相对密实度D_r的主要影响因素,设计加工了包括点式和线式出砂头的成套砂雨装置,讨论了D_r随落距、出砂孔尺寸、出砂头总流量、移动速度的变化规律,分析了D_r空间均匀性分布特征。试验表明：①随落距增大,D_r随之提高,但增速逐渐减缓,可将D_r相对增速K介于±3%所对应落距范围内的D_r均值为稳定相对密实度;②稳定相对密实度与出砂孔尺寸呈线性负相关关系,同一流量下随出砂头移动速度表现出非线性变化特性,出砂头总流量对稳定相对密实度影响不明显;③无论是在水平层面还是沿深度的不同位置,模型箱中部附近的D_r分布均匀性都优于四边和四角处;④一线点式出砂头所制备的砂土D_r与目标值误差较筛孔点式小,具有较好的可控性。

Experimental study on control element of sand pourer preparation of sand foundation model

In order to know the main effect of sand foundation model prepared by sand pourer on the relative density D_r, a set of point and line type sand shakeout device is designed. The variation rules of D_r with the drop height, size of sand production pore, total flow of sand production head and average speed are discussed. The spatial uniform distribution of D_r is analyzed. The tests show that: (1) With the increase of the drop height and potential of sand particles, D_r increases, but the growth rate gradually decreases. So it can be thought that when the relative increase of K of D_r is ±3%, the average value of D_r corresponding to this drop height is called the stable relative density. (2) The stable relative density has negative linear correlation with the size of sand production pore. Under the same condition of total flow, the average speed of sand production head and the stable relative density present nonlinear characteristics. The effect of the total flow of sand production head on the stable relative density is not obvious. (3) For the spatial uniformity distribution characteristics of D_r in the same plane or different planes along the depth, the uniformity of D_r in the center of model box is better than that at the four sides and four corners. (4) The error of actual relative density prepared by the line type of sand production mouth is smaller than that of the point type for target relative density, so the line type of sand production mouth has better controllability for D_r.