Geotechnical behaviour of diaphragm walls.

摘要

To study the geotechnical behaviour of diaphragm walls, the instrumentation of the Greater Cairo Metro project provided the required field measurements. Two test sections were instrumented to observe and record the deformations of the soil, pore water pressures and loads acting on the structural elements (i.e. struts, raft, and roof) due to the excavation and construction method. The first test section was along the running tunnel, an open air excavation using precast panel walls. The second, at a station, was a covered excavation, with cast in situ walls providing lateral support. A finite element analysis was conducted to compute the lateral earth pressures as they can not be measured directly from the field. The use of a simplified plane fram model, run on a microcomputer (such as PFT), to quickly and economically calculate the lateral earth pressures was verified.;The ground reaction characteristics below the groundwater level and a lateral earth pressure concept for diaphragm walls were established. The influence of the construction method, sequence of installation of the temporary and permanent support systems, and the wall thickness were studied for the host material of the Cairo area. As a result, detailed documentation for the Cairo Metro Regional line was provided.