Geogrid reinforcement of granular layers on soft clay

Thesis



The mechanisms by which a geogrid acts to reinforce a granular layer over a soft clay were investigated with reference to trafficking of unpaved roads. The research involved a programme of physical testing at both model and full scale.

Model tests were carried out for monotonic and cyclic loading of a dual footing on to a layer of granular material that was compacted over a consolidated kaolin sample. The tests were made in conditions of plane strain at a quarter scale, and included a scaled geogrid at the base of the granular layer. Measurements of footing load, displacements and photographic observations through a perspex front face to the test box were used to identify the reinforcing actions of the geogrid.

A virtual work procedure was adopted in analysis of the results for both unreinforced and reinforced layers. The procedure accounts for lateral restraint of the subgrade and a membrane action in the reinforced tests, and allows a comparison of the cyclic test results with an equivalent monotonic bearing capacity.

Load tests were also made on footing plates at full scale, involving a similar arrangement of compacted granular layers over a prepared London clay and including a high strength polymer geogrid. Examination of the test results allowed a qualitative assessment of the model performance and the reinforcing mechanisms attributed to the geogrid.

Authors: Fannin, R; Fannin, Robin Jonathan

• Alternative title: a study at model and full scale
• Publication date: 1986
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English