TEST EMBANKMENT FOR IMPROVEMENT OF SOFT CLAYS IN THE COAL YARD CONSTRUCTION AREA AT HEKINAN THERMAL POWER PLANT

Abstract

Among various soil improvement methods for soft soils, preloading with vertical drains is often the most effective method to increase bearing capacity and to reduce residual settlement. For such soil improvement being successfully completed, the most important technical task is the prediction of consolidation behavior and laboratory soil testings made before construction works alone are insufficient to give satisfactory results. Settlement and settlement rate should be monitored carefully during and after execution stage of in-situ loading.In the extensive area of soil improvement project for coal yard construction on soft reclaimed clay at the Hekinan thermal power plant in Nagoya, test embankment was decided and the behavior of the improved soil foundation was monitored, the purpose of which is to provide data to assess total settlement, the rate of consolidation and the increase of undrained shear strength due to partial drainage. The overall performance of the test embankment has shown that vertical drains would be required to get sufficient drainage for both embankment stability and consolidation rate, and would enable preloading to be completed within the duration of the remaining construction program.