Research On Characteristic Deformation Experiment And Numerical Simulation Of Coastal Subgrade

Under the actions of cold climate and paralic environment, there are the adverse factors of freezing and thawing and marine corrosion in north coastal subgrade. It is more difficult for the settlement control of subgrade. Some typical problems, such as the subgrade soil mixed with cement, reinforcing with piles, and the construction disturbance of near tunnel project, make the settlement mechanism of subgrade more complicate. Aiming at above problems, the method combining laboratory test and numerical simulation and theory analysis is employed to study the problems of the north coastal subgrade including soft soil and the soil mixed with cement characteristic, reinforcing with CFG pile, and near construction distribution.Firstly, the subgrade of a road in Dalian rarest four-storey japan-style is experimented, and the grain composition curve and water ratio limit of subgrade are getting, studying the basic physic characteristic and mechanical property. And employing SLB-1type of stress and strain controlled triaxial shear penetration tester to study the intensity index of subgrade, and the variation of intensity parameter of subgrade influenced by different number of freeze-thaw, the mechanical parameters varying laws of subgrade soft soil under the action of cycle of freezing and thawing are acquired.Secondly, the mechanical property of subgrade mixed with ement influenced by north coastal environment is investigated. Employing various test conditions with freezing and thawing, marine corrosion and acid rain erosion to investigate the mechanical characteristic variation of subgrade soil under the action of these factors, the stress and strain-strength-pore pressure change rule of cemented soil with different cement content and liquor and number of freezing and thawing are obtained, also the cemented soil strength degradation rule.And then, aiming at the rheological property of a road with CFG pile in Dalian Binghai road, based on Cvisc model and pile-soil model, the numerical simulations with or without creep and variation of pile parameter are conducted, and the time effect of post-construction settlement of subgrade and the control effect of settlement of subgrade under the action of CFG pile are gained. There is positive guiding significance for the design and construction of subgrade with CFG pile. The compulation result corresponds with the law of project experience observation, illustrating the rationality of numerical simulation method.Finally, for the problem of tunnel piercing below the existing embankment, investigating that the excavating for large section tunnel has influence of the settlement of existing subgrade. Take the bored tunnel below Shenyang-dalian highway6tenders in jinpu line of dalian light rail as research objects, the CRD excavation and support process of tunnel is simulated, and the variation laws of subgrade settlement under the action of the advancement of tunnel face and excavation step sequence are ananlyzed, and changing curve of subgrade settlement with the spatial effect of between excavation face and embankment midpoint is summarized, contrastive analyzing the subgrade settlement corresponding to three kinds of supporting scheme, recommending to use construction measurement of grouting reinforcement.