中央分隔带降水试验分析

通过自制的人工降水仪器,在常德—吉首高速公路路面现场进行中央分隔带降雨试验。通过试验分析了中央分隔带填土的初始含水量和空隙率与排水情况之间的联系,即中央分隔带填土初始含水量和孔隙比越大水渗透的速度越快,横向排水管的出水时间越短。估算出中央分隔带的排水量与降水量的比值,以此来评估中央分隔带的排水能力与效率。阐述了该路段的中央分隔带在排水设计和施工方面存在的问题,并且提出改善中央分隔带排水的建议:(1)在横向排水管埋设的位置设计小窨井,以便于清理,并保证横向排水管的排水能力;(2)可将中央分隔带汇水直接排入人孔,在每个人孔处须预埋管径能满足流量要求的横向排水管;(3)改变中央分隔带内渗沟集水井尺寸,增大集水井的汇水能力,并及时将集水井中的水排出路基外。

Experimental Analysis of Rainfall Simulation at Median of Highway

School of Civil Engineering and Architecture，Central South University，Changsha Hunan 410075，China） Abstract： A field rainfall test on Changde-Jishou expressway was performed by self-made artificial rainfall instrument to investigate the drainage  ability of drainage system of median. By analyzing the test results, the relationship of initial water content and the porosity of filling soil of median with the drainage capacity were investigated, which shows that the larger the initial water content and the porosity of filling soil, the faster the drainage speed and the shorter the drainage time of transverse drainage pipe. Then the ratio of drainage to rainfall was calculated to evaluate the drainage capacity and efficiency of median. Moreover, the problems in terms of drainage design and construction of median were figured out (the key method for improving the efficiency of drainage of median is to ensure the transverse drainage pipe been unhindered), and the suggestions to improve the efficiency of drainage system were supposed: (1)to set a small inspection well at the location of transverse drainage pipe to clear up and maintain the drainage capacity;(2)to drain the collected water directly into the manhole where the radius of each pre-embedded transverse drainage pipe should meet the requirement of drainage ability;(3)to enlarge the size of collecting well of blind-drain in median to improve the capacity of collecting water and then drain the water out of roadbed in time.