Research On Supporting System Of Grade Road Pavement

Subgradeand foundation are the base of pavement. For the reasons that the land resources is limited, the grade road subgrade level is much lower and the expressway manages excess load in the area of the plain.Much subgrade level is about 1m,even lower.The subgrade and the foundation is long-term in owerwet state in water reticulation district,when the water level is higer. Therefore the subgrade bearing capacity of grade road is short, and the strength and stiffness of subgrade changes with the variation of seasons. For that,the fatigue cracking and damage of pavement will occur, and the topdown water breakage of pavement will also happen. Recent years, as the increasingly intisification of supervising expressway overload and overrun vehicles, the heavy -load question of grade road is increasingly severely. And for the thin pavement structure of grade road, the pavement early damage caused by low bearing capacity of subgrade and foundation in flat land water reticulation district is very prominent. Therefore, analyzing the regularity of pavement structure influenced by high water level and the influencing regularity of the pavement structure stress, and presenting the corresponding engineering prophylactico-therapeutic measures have very important engineering and actual significance.Through field detection, indoor test and finite element calculation and analysis, the pavement damaged reasons are analyaed;the stress regularity of pavement structure influenced by high water level is stydyed; analyze the stress regularity of grade road pavement, subgrade and foundation under current subgrade compaction standard, and give the subgrade workspace depth under different traffic axles; analyze the pavement structure mechanics influnce through different treatment schemes of foudation and subgrade under different traffic conditions, and present the treatment technic scheme of foundation and subgrade.Through research, it is regarded that the work space depth reaches more 2 meters under heavy traffic, the current subgrade height of grade road is severely dificient, and larger depth extent under foundation is in subgrade workspace; under norm axle,when the groundwater level is lower than 1.5 meters , the pavement surface flexure reaches 34.07 minimeters and surpasses the design flexure; high water level influences the fatigue life of subgrade and sub-base especially the sub-base; under norm axle, compare the water level 0.5 meter high and unconsidering water level, the bottom course tensile stress of subgrade and sub-base seperately increases 9.25% and 14.72%. Therefoe,water-resisting layer under the subgrade,or the subgrade disposaled by the limestone soil,or the higher subgrade to strengthen the water stability is advised.