关键词: 桩承式加筋路堤, 土拱效应, 现场试验, 三维有限元分析

Abstract:

This paper describes a case history of a geogrid-reinforced and pile-supported (GRPS) highway embankment with a low area improvement ratio of 8.7 %. Field monitored data from contact pressures acting on the pile and soil surfaces, pore-water pressures, settlements and lateral displacements are reported and discussed. The case history is back-analysed by carrying out three-dimensional fully coupled finite element analysis. The measured and computed results are compared and discussed. Based on the field observations of contact stresses and pore-water pressures and the numerical simulations of the embankment construction, it is clear that there was a significant load transfer from the soil to the piles due to soil aching. This transfer greatly reduced excess positive pore water pressures induced in the soft silty clay. For embankment higher than 2.5 m, predictions of stress reduction ratio based on the design methods proposed by Russell and Pierpoint and Hewlett and Randolph are consistent with the measured values and the three-dimensional numerical simulations. For lower embankment, on the other hand, only the method proposed by Russell and Pierpoint gives consistent predictions with the field measurements. During the construction of the piled embankment, the measured lateral displacement-settlement ratio was only about 0.2. This suggests that the use of GRPS system can reduce lateral displacements and enhance the stability of an embankment significantly.

Key words: geogrid-reinforced and pile-supported embankment, soil arching effect, field test, three-dimensional finite element analysis