The intensity of water removal from shallow drainage systems considering the properties of filler materials

To date, there are virtually no experimental studies of drainage structures. The object of the presented study is a road structure with transverse shallow drainage arranged in wet sections of roads. In order to determine the drainage intensity of the drainage structure, an experiment was performed on a special installation for modeling the road structure depending on the properties of filler materials. Parameters of the installation make it possible to arrange a structure that corresponds to real conditions, that is, the parameters of a road of category III and study the processes of formation of the filtration flow in the drainage trench which is impossible with real objects. The laboratory installation was used to study operating conditions of drainage structures: a layer of crushed stone of 20–40 mm fraction and two types of transverse shallow drains with different filler materials in the trench. In the process of a series of experimental studies, the volume of water drained from the trench and drainage time was measured. According to the study results, based on the methods of mathematical statistics, unified equations of the correlation-regression model concerning the mode of operation of the drainage structure were constructed depending on initial soil moisture in the roadbed. According to the results of experimental studies, one of the main indicators of work of shallow drainage structures which depends on the properties of materials of trenches fillers, that is, the drainage intensity was determined. It was found that in contrast to the structure with a PVC pipe filled with coarse sand, the drainage structure with a crushed stone core in the trench worked in one mode of the formed flow. The work of the structure with the pipe is divided into short-term and long-term modes depending on the drainage intensity. The obtained regression dependences enable forecasting of the amount of water drained by the proposed drainage structures in a certain period for field conditions