Faisal Haji Ali

Field behaviour of a geogrid-reinforced slope

Abstract Geogrids are high-strength, orientated-polymer grid structures used to reinforce soils. This paper deals with the design, construction, and performance of the rehabilitation work for a 16-m high-slope failure in Malaysia. The rehabilitation scheme consisted of (i) a steep (70°) reinforced-soil wall at the lower end, and (ii) an upper reinforced gentle slope. The reinforced-soil structure, which was 7 m high, was reinforced with geogrids. In order to examine the performance of the rehabilitation scheme in the field, instrumentation was provided to monitor forces in the reinforcements, horizontal and vertical movements, earth pressures, and pore water pressures.

THE FLOW BEHAVIOUR OF DEFORMED PREFABRICATED VERTICAL DRAINS

Abstract There are various factors which affect the longitudinal permeability of a vertical drain and one of the most important is the soil deformation. As the surrounding soil settles during consolidation each vertical drain deforms since the drain is considerably less compressible than the surrounding soil. This paper describes an investigation on the combined effect of lateral pressure and the soil deformation on the longitudinal permeability of prefabricated vertical drains. A few common types of prefabricated drains were tested and variations in discharge capacities with soil settlement and lateral pressure were determined. The results show that soil settlement gives a significant effect on the discharge capacity.

A New Technique for Driven Piles Instrumentation

Currently, strain gauges are normally used to monitor the strain development in the pile during static pile load test. For concrete spun pile, the technique used either by incorporating high temperature-resistant strain gauges into the heat-cured production process of the spun piles or by installing an instrumented steel pipe into the hollow core of the spun piles followed by cement grout infilling. The former is extremely unpopular due to high cost of these gauges and the uncertainty over their ability to survive the pile production and driving processes. The shortcoming of the other technique is the infilling of cement grout substantially alters the structural properties of the piles, thus, rendering their load-response behaviour significantly different from that of the actual working piles. This paper highlights the application of a method, recently developed by the authors, which uses retrieval sensors instead of strain gauges which have to be sacrificed in every test. The method is particularly useful to monitor loads and displacements at various levels along the pile shaft and toe of instrumented piles. Results of field tests show high quality, reliable, and consistent data, clearly far exceeding the capability of both conventional methods of using strain gauges.