Soil-Culvert Interaction (2010-2011)
CENTRIFUGE TESTS FOR STATIC AND SEISMIC SOIL-CULVERT-INTERACTION (SCI) OF SQUARE BOX CULVERT INSIDE A DRY COHESIONLESS SOIL
Box culverts are very important part of the life-line structures which may subject to static and dynamic loading. The distribution of pressure around box culverts can lead to what is called “Soil Arching”. This can lead to increase or decrease of the loading on the structure. The failure of box culverts due to earthquakes can take different forms such lateral spreading, surface faulting, increase in the earth pressure on the roofs and sides of the box culverts. The risk of these earthquake consequences for these very important life-line structures can cause very danger situations that should be avoided. Detailed studies show that effect under static and seismic loading is still absent in the literature. This research is to explore and study the effect of static loads due to both the self weight of the soil and foundation loads as well as the effect of dynamic loads by the application of different earthquakes that has different amplitudes and frequency contents.
Description of the experimental activities
The experimental activities consist of 4 tests for two different culvert thicknesses at 50% and 90% relative densities. Each test will include all the stages starting with the effect of soil pressure only and then adding the foundation load at the surface. At the end of each stage, 7 shakings will be applied to the model depending on the capability of the shaker.
This Photo shows the model after completing the building and before mounting to the centrifuge. The setup of the model includes putting the sand into layers separated by blue line colors to achieve the required density and to monitor any movement in the culvert during running the test. Some accelerometers were distributed at different locations inside the sand to measure the change in the acceleration time history at different points at free field and at structure field. Also the culvert was placed at the center of the centrifuge box so it has the same height of sand above and below. The culvert itself is surrounded by some sensors such as strain gauges and tactile to measure the actual soil pressure on the culvert.
This photo shows the model after mounting it on the centrifuge. It shows also the hooking of all the sensors to the DAQ. As shown, it includes also three LVDTs placed on the surface to monitor the settlement of the surface during static and shakings stages. It also shows the connection of the tactile handles to the sensors which are placed on the top of sand surface.
This photo shows the addition of the Foundation in the middle of the sand surface right above the culvert directly. In this case the LVDT in the middle where placed right on top of the foundation. This time, the addition of the pressure coming from the foundation will be monitored.