Investigation of the behavior of rigid culverts under high filling by experimental methods

The transport is one of the most important elements of human history, which provides a unity with many subheadings. Our study is on the culverts used effectively in road transport. Box culverts are exposed to traffic load and embankment pressure (vertical and horizontal) due to cushioning. The magnitude of the earth pressure due to the high amount of fill creates stresses and deformations on the box culvert surface. In order to resist this high pressure, either the reinforced concrete sections of the box culvert are enlarged or lightweight materials are used as backfill. In this study, the behaviour of two different geometries of box culverts produced in the laboratory was investigated under loading. In order to provide more resistance against vertical and horizontal loads on the box culvert, a protrusion was made at the top of the box culvert and it was aimed to reduce the horizontal pressure by keeping the vertical loads in this protrusion cavity. The box culvert of normal cross section (200x240x500 mm) was loaded as a distributed load by using a closed loading system at different compaction values of Şile quartz sand selected as filling material and its behaviour was investigated. In addition, the box culvert with changed geometry, which is described as load throwing culvert in the literature, was also loaded in the same way at three different fill material compaction values (loose, medium-tight and tight soil) and the results were evaluated. As a result of the experiments, as the degree of compaction (tightness) of the backfill material increases, both the load carried by the box culvert increases and the vertical and horizontal displacements in the culvert decrease. Similar situation is observed in the load reducing culvert type according to the degree of compaction. When the two types of culverts are compared with each other, the second type of culvert (load reducing culvert) carries more load and has less vertical and horizontal displacement. Especially the lateral earth pressure is reduced to a great extent.