Numerical analysis of the effects of subgrade settlement on top-down cracking in epoxy asphalt pavement

Epoxy asphalt pavement cracking caused by subgrade settlement is detrimental to the long-term safe service of roads.A threedimensional finite element model of epoxy asphalt pavement is established to investigate the effects of subgrade settlement on the propagation of top-down cracking(TDC).The contour integral method is utilized to calculate the stress intensity factor(SIF)at the crack tip,and then the extended finite element method(XFEM)is used to analyze the propagation behavior of TDC under combined subgrade settlement and traffic loading.The results of these analyses indicate that increased subgrade settlement,stiffer surface layers,and softer bases will increase the SIF,resulting in a faster crack propagation rate.It is suggested that the use of epoxy asphalt materials in pavement structures can allow more subgrade settlement than conventional asphalt mixtures.However,when the base layer modulus is higher than 12500 MPa,the increase in surface modulus can decrease crack propagation length.Sensitivity analysis results demonstrate that subgrade settlement has the most significant impact on TDC propagation.The conclusions of this study are expected to provide a theoretical basis for crack prevention in the design and maintenance of pavement structures.

Settlement patterns of mountainous half-filled and half-cut widened subgrade with retaining wall

The settlement of widened highway subgrade in mountainous area is not only affected by the interaction between new and existing subgrade, but also seriously restricted by the external retaining wall. Based on the practical engineering of half-filled and half-cut widened mountainous highway subgrade with external balance weight retaining wall(BWRW), a sophisticated finite element numerical model is established. The evolution law of subgrade settlement is revealed during the whole process of new subgrade filling and BWRW inclination after construction. The settlement component of subgrade is clarified considering whether the existing pavement continues to be used. The results show that the additional settlement caused by the BWRW inclination after construction cannot be ignored in the widening and reconstruction of mountainous highway subgrade. In addition, pursuant to the comprehensive design of subgrade and pavement, the component of subgrade settlement should be determined according to whether the existing pavement continues to be used, while considering the influence of BWRW inclination after construction. When the existing pavement continues to be used, the settlement of the existing subgrade is caused by the new subgrade filling and the BWRW inclination after construction. On the contrary, the settlement is only caused by the BWRW inclination after construction.

Technical Analysis of Subgrade and Pavement Construction in Settlement Section of Municipal Road and Bridge Engineering

The construction of municipal roads and bridges is an important foundation for the smooth traveling and transportation.However,if there a reduction in the subgrade and pavement part,the safety and the comfort of the driver will be seriously affected,therefore,reasonable measures should be taken on time to tackle the related issues.The significance of subgrade and pavement construction in the subsidence section,the key points of the construction,and the appropriate control measures that are should be taken in the actual construction,was discussed in this paper.Further,this paper analyzes the availability of the subgrade and pavement construction technology for the municipal roads and bridges,to provide a reference for engineers.

Load-settlement behaviour of a strip footing resting on iron ore tailings as a structural fill

This study presents a laboratory investigation of load-settlement behaviour of a strip footing resting on iron ore tailings used as a structural fill.The footing was placed at various depths in the tailings bed.The relative density of the tailings was varied as D_r = 50%,70%and 90%.An incremental load was applied on the footing while observing the settlement until the failure took place.The results obtained for tailings were compared with those for the sandy soil.It is observed that the load-bearing capacity and stiffness increase with an increase in footing embedment depth and relative density.Compared to load-settlement behaviour of Perth sandy soil,the tailings fill could have as high as 22 times and 13.5 times the load-bearing capacity and stiffness,respectively.Therefore,the replacement of sandy soil with iron ore tailings for structural fills is cost-effective,and moreover,this application contributes to environmental sustainability in construction.