The objective of this work is to compare the responses of geosynthetically-reinforced embankment and unreinforced embankment due to road widening by using the centrifuge model tests and a two-dimensional(2D) finite el...The objective of this work is to compare the responses of geosynthetically-reinforced embankment and unreinforced embankment due to road widening by using the centrifuge model tests and a two-dimensional(2D) finite element(FE) model. The measured and calculated responses of the embankment and foundation exposed to road widening include the settlement,horizontal displacement,pore water pressure,and shear stresses. It is found that the road widening changed the transverse slope of the original pavement surface resulting from the nonuniform settlements. The maximum horizontal movement is found to be located at the shoulder of the original embankment. Although the difference is small,it is clearly seen that the geosynthetic reinforcement reduces the nonuniform settlements and horizontal movements due to road widening. Thus the reinforcement reduces the potential of pavement cracking and increases the stability of the embankment on soft ground in road widening.展开更多
A research project was initiated by INDOT to estimate the structural contribution and feasibility of FDR bases for pavement structure under a low-medium volume traffic loading. FWD tests were conducted and the layer m...A research project was initiated by INDOT to estimate the structural contribution and feasibility of FDR bases for pavement structure under a low-medium volume traffic loading. FWD tests were conducted and the layer moduli were back calculated on different construction phases： the surface of existing HMA pavement, the FDR base, the new HMA final surface, and the nine months＇ traffic opening, respectively, for a total of four times. The results indicate the promise of this recycled base material in pavement construction compared to traditional granular base. In addition, this paper discusses how the lab test results relate to the expected performance in a pavement structure by the MEPDG software and its parameter effects. Research indicated the MEPDG provided comparable thickness to the 1993 AASHTO Guide if the failure criteria are set up reasonably. Therefore, the MEPDG could be used as a design tool to estimate layer thickness for FDR pavement with a low-medium traffic volume.展开更多
Ten years of ground temperature data(2003–2013) indicate that the long-term thermal regimes within embankments of the Qinghai-Tibet Railway(QTR) vary significantly with different embankment structures. Obvious asymme...Ten years of ground temperature data(2003–2013) indicate that the long-term thermal regimes within embankments of the Qinghai-Tibet Railway(QTR) vary significantly with different embankment structures. Obvious asymmetries exist in the ground temperature fields within the traditional embankment(TE) and the crushed-rock basement embankment(CRBE). Measurements indicate that the TE and CRBE are not conducive to maintaining thermal stability. In contrast, the ground temperature fields of both the crushed-rock sloped embankment(CRSE) and the U-shaped crushed-rock embankment(UCRE) were symmetrical. However, the UCRE gave better thermal stability than the CRSE because slow warming of deep permafrost was observed under the CRSE. Therefore, the UCRE has the best long-term effect of decreasing ground temperature and improving the symmetry of the temperature field. More generally, it is concluded that construction using the cooling-roadbed principle meets the design requirements for long-term stability of the railway and for train transport speeds of 100 km h?1. However, temperature differences between the two shoulders, which exist in all embankments shoulders, may cause potential uneven settlement and might require maintenance.展开更多
基金Project(200231800032) supported by Research on Transportation Construction in Western, China
文摘The objective of this work is to compare the responses of geosynthetically-reinforced embankment and unreinforced embankment due to road widening by using the centrifuge model tests and a two-dimensional(2D) finite element(FE) model. The measured and calculated responses of the embankment and foundation exposed to road widening include the settlement,horizontal displacement,pore water pressure,and shear stresses. It is found that the road widening changed the transverse slope of the original pavement surface resulting from the nonuniform settlements. The maximum horizontal movement is found to be located at the shoulder of the original embankment. Although the difference is small,it is clearly seen that the geosynthetic reinforcement reduces the nonuniform settlements and horizontal movements due to road widening. Thus the reinforcement reduces the potential of pavement cracking and increases the stability of the embankment on soft ground in road widening.
文摘A research project was initiated by INDOT to estimate the structural contribution and feasibility of FDR bases for pavement structure under a low-medium volume traffic loading. FWD tests were conducted and the layer moduli were back calculated on different construction phases： the surface of existing HMA pavement, the FDR base, the new HMA final surface, and the nine months＇ traffic opening, respectively, for a total of four times. The results indicate the promise of this recycled base material in pavement construction compared to traditional granular base. In addition, this paper discusses how the lab test results relate to the expected performance in a pavement structure by the MEPDG software and its parameter effects. Research indicated the MEPDG provided comparable thickness to the 1993 AASHTO Guide if the failure criteria are set up reasonably. Therefore, the MEPDG could be used as a design tool to estimate layer thickness for FDR pavement with a low-medium traffic volume.
基金supported by the National Basic Research Program of China(Grant No.2012CB026101)the Western Project Program of the Chinese Academy of Sciences(Grant No.KZCX2-XB3-19)+1 种基金the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Grant No.41121061)the National Sci-Tech Support Plan(Grant No.2014BAG05B05)
文摘Ten years of ground temperature data(2003–2013) indicate that the long-term thermal regimes within embankments of the Qinghai-Tibet Railway(QTR) vary significantly with different embankment structures. Obvious asymmetries exist in the ground temperature fields within the traditional embankment(TE) and the crushed-rock basement embankment(CRBE). Measurements indicate that the TE and CRBE are not conducive to maintaining thermal stability. In contrast, the ground temperature fields of both the crushed-rock sloped embankment(CRSE) and the U-shaped crushed-rock embankment(UCRE) were symmetrical. However, the UCRE gave better thermal stability than the CRSE because slow warming of deep permafrost was observed under the CRSE. Therefore, the UCRE has the best long-term effect of decreasing ground temperature and improving the symmetry of the temperature field. More generally, it is concluded that construction using the cooling-roadbed principle meets the design requirements for long-term stability of the railway and for train transport speeds of 100 km h?1. However, temperature differences between the two shoulders, which exist in all embankments shoulders, may cause potential uneven settlement and might require maintenance.
