| Hong-gu-tan road (total length is 13km) stands on the northem bank of Gan River, which is one of city main roads in Nanchang City. The Hong-gu-tan road is used for transportation, flood control, market and entertainment. The top width of subgrade and height of embankment are 30m and 9m respectively. As the embankment was filled twice, the first filling is up to the height of 23m and the second filling is up to the height of 25.8m. But domestic wastes and construction wastes on the embankment were not cleared completely before the second filling, which resulted in the cracking and subsidence of concrete pavement in part road sections after the road was open to traffic. For establishing city image and ensuring unimpeded main roads, treating road sections of miscellaneous fill well has become the technical problem that was necessary to be solved for Nanchang City Government.Therefore, the research of the treating technique for miscellaneous fill road sections along rivers is carried out in the paper.Based on the geological investigations by boring and sampling in six positions chosen from the road sections of K4+550～K4+735 and K8+600～K8+700, geological conditions and soil parameters were analyzed firstly, providing comprehensive datum of geological and soil property for the scheme selection of embankments' treatments.Through the analysis and research of Compound Foundation Techniques for treating soft soil foundations, Compound Foundation Techniques and their reinforcement mechanisms (such as methods of cement deep layer stirring, compaction, vibrofloatation, and high pressure jet grouting etc.) are discussed, and then we refer to such technique principles to treat diseases of miscellaneous fill embankments and pavements. Combined with successful experience of existent miscellaneous fill embankment treating schemes, with regard to several requirements of ensuring flood control, reducing construction period, making roads unlocked and protecting environments etc., the scheme selection of such embankment treating was done systematically. Properly, select piecewise and carry out three kinds of techniques of cement deep layer stirring pile, vibro crushed stone pile and spinning jetting pile to reinforce embankments comprehensively.Based on elaborating reinforcing mechanisms, design theories and applicability of Compound Foundation Techniques in detail,, material and instruments, construction process, construction technology and treating effects for techniques of cement deep layer stirring pile, vibro crushed stone pile and spinning jetting pile, that were used to treat Nanchang Hong-gu-tan road embankment, are introduced comprehensively. The results of dead load test of base pile, motoring of embankment settlement and physical and mechanics parameters' tests of soils among piles showed that, the pile-forming effects of cement deep layer stirring pile and vibro crushed stone pile were good, and the spinning jetting piles located on both sides of embankment were taken as curtain and have the effect of precompaction. At the same time, the bearing capacity of compound foundation increased evidently, the physical and mechanics characteristics of soils among piles after treatments was better than ones before treatments. Accordingly, the aim of increasing integrated bearing capacity and controlling settlement was achieved.The treating project in Hong-gu-tan road has experienced five years' trials, and the service performance is still good, which accumulates experiences for forward similar projects. |
PDF Full Text Request