High costs are connected with upgrading railway embankments throughout Denmark using the partial factors for geotechnical design calibrated for general application. One way to reduce the costs is reliability-based cal...High costs are connected with upgrading railway embankments throughout Denmark using the partial factors for geotechnical design calibrated for general application. One way to reduce the costs is reliability-based calibration of the partial factors to a reasonable safety level taking into account the specific design situations and uncertainties relevant to railway embankments. A reliability-based design has been investigated, resulting in an optimal partial factor for the considered subsoil. With a stochastic soil model to simulate the undrained shear strength of soft soil deposits, the partial factor is calibrated using asymptotic sampling for the reliability assessment. The calibration shows that the partial factor can be reduced significantly compared to the value specified in the Danish National Annex to DS/EN 1997-1 (2007), Eurocode 7.展开更多
In permafrost regions, the embankment settlement results from several physical and mechanical processes taking place in the different soil layer, making its mechanism very complicated. Under the thermal influence of e...In permafrost regions, the embankment settlement results from several physical and mechanical processes taking place in the different soil layer, making its mechanism very complicated. Under the thermal influence of embankment, climate warming as well as geothermal source, permafrost may degrade downwards or upwards, which continuously changes the thicknesses of the permafrost layer and the also unfrozen soil layers. Thus, any attempt to analyze the embankment settlement seems to be very troublesome and difficult. In this paper, based on ground temperatures of embankment sections in five typical regions along the Qinghai-Tibet Highway (QTH), the trends of variation of different soil layers and the thermal gradients are investigated. On this basis, four types of sections, which can represent most of the sections of QTH, are deduced to clarify the possible settlement sources in different soil layers. In order to further confirm and investigate of the settlement sources, an embankment model test was carried out. Combing the in-situ monitoring data with the results from the model test, the main settlement sources in embankment settlement are discussed for the four types of sections respectively. The results will facilitate the analysis of embankment settlement in permafrost regions.展开更多
基金The funding initiating this work was provided by Banedanmark
文摘High costs are connected with upgrading railway embankments throughout Denmark using the partial factors for geotechnical design calibrated for general application. One way to reduce the costs is reliability-based calibration of the partial factors to a reasonable safety level taking into account the specific design situations and uncertainties relevant to railway embankments. A reliability-based design has been investigated, resulting in an optimal partial factor for the considered subsoil. With a stochastic soil model to simulate the undrained shear strength of soft soil deposits, the partial factor is calibrated using asymptotic sampling for the reliability assessment. The calibration shows that the partial factor can be reduced significantly compared to the value specified in the Danish National Annex to DS/EN 1997-1 (2007), Eurocode 7.
基金supported in part by the National Natural Science Foundation of China (No. 41172253)the National Natural Science Foundation of China (No. 41201064)+2 种基金the Foundation of the State Key Laboratory of Frozen Soils Engineering, CAS (No. SKLFSE-ZQ-28)the Foundation for Excellent Youth Scholars of CAREERI, CAS (No. Y451091001)the European Community through the program "People" as part of the Industry-Academia Pathways and Partnerships project CREEP (No. PIAPP-GA-2011-286397)
文摘In permafrost regions, the embankment settlement results from several physical and mechanical processes taking place in the different soil layer, making its mechanism very complicated. Under the thermal influence of embankment, climate warming as well as geothermal source, permafrost may degrade downwards or upwards, which continuously changes the thicknesses of the permafrost layer and the also unfrozen soil layers. Thus, any attempt to analyze the embankment settlement seems to be very troublesome and difficult. In this paper, based on ground temperatures of embankment sections in five typical regions along the Qinghai-Tibet Highway (QTH), the trends of variation of different soil layers and the thermal gradients are investigated. On this basis, four types of sections, which can represent most of the sections of QTH, are deduced to clarify the possible settlement sources in different soil layers. In order to further confirm and investigate of the settlement sources, an embankment model test was carried out. Combing the in-situ monitoring data with the results from the model test, the main settlement sources in embankment settlement are discussed for the four types of sections respectively. The results will facilitate the analysis of embankment settlement in permafrost regions.