| dc.description.abstract | The thesis is concerned with the effects of slurry trenching (diaphragm wall
installation) in an overconsolidated clay, with particular emphasis on the changes in
lateral stress which occur.
A review of the literature on diaphragm wall installation in stiff overconsolidated clay
was carried out, with particular reference to the measurement of changes in stress and
the application of finite element analyses. The problem was investigated by means of
centrifuge model tests and finite element analyses.
The main body of the thesis details the development and results of a series of
centrifuge tests. A model at 1 to 100 scale was tested at 100 gravities, enabling both
the long and short term effects of slurry trench walling to be investigated. The
technique adopted used a fluid-filled neoprene rubber bag in the place of the trench
that was drained to ground level to simulate excavation under bentonite slurry. A
mixture of plaster of Paris, iron-filings, fine sand and cement powder was then
deposited into the bag to simulate wall placement.
By using different fluid heights of different densities in the rubber bag, a series of
initial earth pressure coefficients were modelled. The effects of both a stress and
strain controlled boundary at the remote end of the model were also investigated.
Finally, simulated concretes of different densities were adopted to see what effect this
would have on placement stresses.
A technique was developed to enable the measurement of changes in total lateral
stress changes at up to 10 locations within the model. Pore water pressures were
measured at the same positions, and ground settlements were measured at the surface
of the model.
A series of finite element analyses was carried out to extend the scope of the
centrifuge model results by varying further the initial in situ conditions. The
conclusions and suggestions for further work are presented at the end of the thesis. | en_US |
