沟埋涵洞土拱效应及涵顶垂直土压力研究

采用细观颗粒流软件PFC^2D对沟埋涵洞上方填土内土拱效应及涵顶垂直土压力进行研究。结果表明:涵洞上方填土越高,土拱效应越明显;沟槽越宽,土拱效应越弱。土拱形态为上凸形,拱脚位于两侧沟壁上,可以根据填土内竖向位移等值线是否出现椭圆形来判断填土内是否产生明显土拱效应。沟槽宽度大于7倍涵洞宽度时,涵顶垂直土压力可按上埋式涵洞土压力的方法进行计算。涵顶土压力系数随着填土高度的增加呈先增后减的变化趋势。当填土高度达到初始等沉面高度时,土压力系数达到最大值。等沉面高度随着填土高度的增加而下降,随着沟槽宽度的增加而上升。并在此基础上得出了考虑土拱效应的涵顶垂直土压力计算判别准则及计算方法。

Soil Arching Effect and Vertical Earth Pressure on Trench Installation Culverts

A numerical analysis is carried out using the software Meso-scale Particle Flow Code (PFC^2D) to investigate the soil arching effect in the backfill and the vertical earth pressure on trench installation culverts. Research findings indicate that the soil arching effect is more obvious for higher backfill over the culvert, but it is not obvious at a wider trench width. The form of the soil arching is convex and the arching springers are located on both sides of the trench wall. The soil arching will be obvious if there is an ellipse in the vertical displacement contour lines of the backfill. The vertical earth pressure on the top of trench installation culverts can be calculated by using a theoretical method for calculating that of positive installation culverts when the trench width is larger than 7 times the culvert width. The vertical earth pressure coefficient first increases nonlinearly with the backfill height and then has a decrease. It reaches the maximum value when the backfill height reaches to the initial equal settlement plane. The elevations of equal settlement plane decreases with the backfill height and increases with the trench width. Moreover, a calculating criterion and method for the vertical earth pressure on the top of trench installation culverts has been deduced with considering the soil arching effect.