科研之友
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摘要
Soil nailing is a technique routinely used in Hong Kong whereby closely spaced steel bars are installed into a slope so that the stability conditions of slopes comprising either in-situ or compacted soils can be improved. A full-scale field test has been carried out by The Department of Civil Engineering of The University of Hong Kong to study the development of passive load along the full length of soil nails when subjected to induced rise in groundwater table. The cut slope was formed to a very steep angle of 55 degrees and 10 m high in completely decomposed volcanic material. Grouted curtain was also formed behind, bottom and on both ends of the slope in order to form an impermeable barrier that would allow groundwater table to increase artificially by injecting water into slotted PVC inlet pipes. Nine number of soil nails (in regular 2 m c/c spacing of 3 rows and 3 columns) of 6 m long high yield steel bar were installed at 15 degrees from horizontal into the formed cut slope. Instrumentation included strain gauges along the nails, inclinometers, piezometers, moisture probe and settlement prisms. This paper describes the load developed along the instrumented soil nails when the groundwater table was raised to the ground surface. It was found that the measured passive load along the soil nail was smaller than the commonly assumed design parameters, an indication that substantial savings can be achieved if mobilization of shearing resistance along the full length of the soil nail was considered in routine design. Finite element analysis has also been carried out to compare the stability factor with the factor of safety. A comparison of factor of safety of this soil nailed system using conventional limit equilibrium and that from strength reduction technique is also described in this paper.
- 出版日期2008
- 单位香港大学
