泥石流常用排导槽水力条件的比较

目前泥石流防治工程中广泛采用的横断面型式主要有直墙V型断面、梯型断面、矩型断面、圆型断面。将泥石流排导槽的断面型态系数定义为湿周与水力半径之比,在此基础上推导出直墙V型、梯型、矩型、圆型排导槽水力最佳时相应的断面型态系数,对相同槽型排导槽水力断面的研究表明:直墙V型槽横坡系数在0～3时,随横坡系数增大,水力条件更优;横坡系数大于3后,随横坡系数的增大,水力条件越差;横坡系数等于3时,水力条件最佳。梯型槽边坡系数在0～0.577时,随边坡系数增大,水力条件越优;边坡系数大于0.577后,随边坡系数的增大,水力条件越差,边坡系数等于0.577时,水力条件最佳。对直墙V型、梯型、矩型、圆型槽的水力最佳断面进行了分析比较,结果表明:圆型断面排导槽水力条件比其他3种都优;当边坡系数大于0,小于等于1.333时,梯型槽较矩型断面优越;当边坡系数大于1.333时,梯型槽没有矩型槽优越。当横坡系数大于0,小于0.75时,直墙V型槽没有矩型优越;当横坡系数大于0.75时,直墙V型槽比矩型优越;在横坡系数、边坡系数值相同的情况下,且在0与1之间时,梯型槽比直墙V型槽优越;当大于1时,梯型槽没有直墙V型槽优越;当两者均为1时,水力条件相同。

COMPARISON OF HYDRAULIC CONDITIONS AMONG USUAL DEBRIS FLOW DRAINAGE CANAL

The triangular,trapezoid,rectangular and circular transects are applied as debris flow drainage canal widely at present.The section factor coefficient is defined as the ratio of wet perimeter and hydraulic radius,and the section factor coefficients of four kinds of debris flow drainage canals(trianglet,rapezoidr,ectangle and rotundity) are deduced.When the bed slope coefficient of triangular drainage canal is greater than 0 and less than 3,with the bed slope coefficient increasingt,he hydraulic condition is more advantageous.And while the bed slope coefficient is greater than 3t,he hydraulic condition become disadvantageous.The hydraulic condition of debris flow drainage canal is best as the bed slope coefficient is equal to 3.When the bed slope coefficient of trapezoid drainage canal is greater than 0 and less than 0.577,with the bed slope coefficient increasing,the hydraulic condition is more advantageous.While the bed slope coefficient is greater than 0.577,the hydraulic condition become disadvantageous,and the hydraulic condition of debris flow drainage canal is best as the bed slope coefficient is equal to 0.577.The hydraulic condition of circular section is best among four kinds of drainage canals.when the bed slope coefficient of trapezoid is greater than 0 and less than 1.333,the hydraulic condition of trapezoid section is better than rectangular section,and when the bed slope coefficient excesses 1.333,the rectangular section is better than the trapezoid section;when the bed slope coefficient of triangular is greater than 0 and less than 0.75,the hydraulic condition of the rectangular section is better than that of the triangular section,as the bed slope coefficient excesses 0.75,the triangular section is better.Under the same bed slope coefficient condition,the trapezoid section is better than the triangular one.When the bed slope coefficient is among 0 and 1,and the bed slope coefficient is 1,the hydraulic condition is the same.