Ground improvement for enhancing the performance of road, rail, and port infrastructure
A great deal of the world's transport infrastructure is built along congested coastal belts that consist of highly compressible and weak soils with very low bearing capacity and excessive settlement charac-teristics, so stabilising them before construction will guarantee long term and short term stability. Pre-construction consolidation of soft soils via a surcharge load alone often takes too long, and the load required to achieve more than 90% consolidation can be excessively high over a prolonged period, which is why a system of vertical drains combined with vacuum pressure and surcharge preloading has become an attractive alterna-tive for ground improvement. This technique accelerates consolidation by enabling a rapid radial flow which decreases the excess pore pressure while increasing the effective stress. Ballasted railroads form one of the major worldwide transportation networks and they continue to provide quick and safe transportation. As the axle loads and number of high-speed trains' increases, so the quality of track substructure becomes extremely important, and the excessive deformation and degradation of the granular media and unacceptable differential settlement of soft subgrade necessitates frequent track maintenance. To rectify these problems, the use of arti-ficial inclusions in the rail environment has been effective. Field measurements, analytical approach and nu-merical modelling are among the methodologies used to evaluate the effectiveness of these artificial inclu-sions. Comprehensive field trials were carried out to assess the role of geogrids, geocomposite, and shock mats in stabilising ballast embankments at Bulli and Singleton, New South Wales, Australia. Large-scale triaxial tests were conducted to investigate the behaviour of reinforced and un-reinforced subballast under cyclic load using process simulation triaxial apparatus. Geocells influenced the behaviour of subballast under cyclic load-ing, particularly at low confining pressure and high frequency. Coal wash (CW) and basic oxygen steel slag fines (BOS) were used as fill for the reclamation project at the Outer Harbor extension of Port Kembla, at Wollongong, NSW. The laboratory investigation on the optimum CW-BOS mixtures is depicted here. Fur-thermore, a new methodology using a field evaluation of the shear wave velocity (Vs) combined with matric suction (ua-uw) or moisture content was applied to assess compaction at Penrith Lakes, NSW. This paper de-scribes an evaluation of the performance of artificial inclusions and compaction control using laboratory test-ing, analytical approaches, numerical modelling and field measurements.
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