Research On The Settlement Of Embankment And Mechanism Of Pavement For Freeway

Relying on research projects "settlement of embankment and mechanism of pavement for freeway" supported by Hunan Traffic and Communication Department, the paper studied on long-term deformation of red sandstone as road fillings of freeway and dynamic response of pavement under traffic load occurred to embankment and pavement of operated freeway. To be specific they are settlement prediction of stone and soil embankment, long-term deformation of embankment, description and confirmation of traffic dynamic load, excitement property, dynamic response of embankment and pavement under bearing condition. Many methods like theoretic analysis, in-door tests, on-the-spot tests and numeric calculation are taken into use in this paper. The major studied contents include:1. A great deal of work has been done for the research on the problems of operated freeways within Hunan Province. The paper makes the emphasis on three freeways Linchang, Tanlei, Leiyi freeway. It consults design paper and construction record of these freeways. The research shows that diseases of red stone embankment are related to the operation time and traffic load of freeway. There are reasons for diseases of freeway: long-term reaction effect of traffic dynamic load, and rheology deformation of red stone fillings of embankment under long-term load effect.2. Uneven settlement prediction is a very effective way to prevent embankment diseases. The observed the settlement values are the real values under comprehensive factors. Therefore, it is of great significance to use actual observed settlement value to calculate embankment settlement. Compared to many settlement prediction, it stresses Gray GM(1.1) and nerve network method.3. It introduces Burgers model which takes into consider of rheology, and adopts FLAC program. It makes prediction calculates of long-term settlement and makes it compared with actual observe values to test the rationality of model.4. From the excitement of random vibration of vehicles, it uses frequency domain method and generalized PSD properties and law of unevenness of freeway. Based on physical mechanic properties of flexible road surface and with reference to pertinent files, transfer function matrix was adopted via theory of layered system after transformation through Fourier and Laplace integration; it predicts solution of dynamic equation of multiple viscoelastic system under moving harmonic loads. It analyzes and evaluates various vehicle vibration model.5. As for the vehicle load, it chooses typical stone and soil embankment. It successfully conducts the tests of on-the-spot vehicle random load. The tests reveal the excitement property, effect and other factors under various load, vehicle speed, driving directions, and illustrate the relations between structure property of embankment and excitement of load.6. With buried devices under embankment during construction, it successfully conducts tests on dynamic response of embankment and pavement under random vehicle load. It studies how factor like vehicle load, speed, lane affects embankment and pavement, and analyzes frequency spectrum and power frequency spectrum of dynamic response compare them with unevenness excitement property of pavement. The results show that there exits cause-effect relationship among them.7. Through emulation of 3-D dynamic FEM model of flexible roadbed and surface, it analyzes the dynamic response under dynamic vehicle load on the pavement of stone and soil fillings, and compare the numerical values and actual observed values.