| Semi-rigid base asphalt pavement is widely used in domestic high-grade highways due to its excellent road performance,but the problem of reflection cracks in itself has not been solved so far.Existing research data indicate that there are many semi-rigid base asphalt pavements in northern China that have been built after one or two winters.After one or two winters,there will be a large number of horizontal cracks on the road surface.These cracks will accelerate the damage of the asphalt pavement and lead to a long service life of the road.reduce.There have been many studies on the cracking of semi-rigid base asphalt pavement at home and abroad,but there are still many problems in the prevention and treatment of reflective cracks in asphalt pavement.In this paper,the methods of finite element simulation and field test are used to study the measures to prevent reflection cracks in the semi-rigid base layer reinforced with basalt geogrid.Through the investigation of road diseases in Zhangjiakou,Hebei Province,it was found that the most road diseases in this area were horizontal cracks,and then other pavement diseases such as potholes and cracks.The ABAQUS software is used to establish the road structure model and the basalt geogrid model,and then simulate and calculate according to the designed working conditions.The calculation results show that whether the basalt geogrid is placed between the base layers or at the junction of the base layer and the base layer,the semi-rigid base layer can be effectively prevented from cracking;according to the stress level of the crack position of the base layer and the upper base layer of the road structure model,it can be known The effect of placing the basalt geogrid in the base is better than that of placing it at the junction of the base and the base;comparing the stress diagrams of the base and the upper base under different design conditions,the following conclusions can be drawn: the effect of placing the geogrid in the middle of the base It is better than placing the geogrid on one-quarter and three-quarters of the base.A test section was built at the Chicheng branch line of Yan-Chong Expressway in Hebei Province.The test section is one kilometer long and divided into three working conditions.In condition I,the basalt geogrid was placed at one-half of the base,and in condition II,the grid was placed at the junction of the base and the subbase.Condition III was used as a control group without the geogrid.According to the analysis of the results of the field test,the strain values of working conditions I,II,and III gradually decrease with the decrease of temperature,and gradually increase with the increase of temperature,and the variation range of the strain value of the base layer is larger than that of the base layer;The I base layer has a tensile strain of 400με,the working condition II has a tensile strain of 600με,and the working condition III has a tensile strain of 800με;the strain change gradually increases with the increase of the temperature change,when the temperature change increases to one Timing,the strain change amplitude gradually decreases and stabilizes.Finally,based on the results of field test data analysis and finite element simulation,the following conclusions are drawn.Placing basalt geogrid in the base can greatly reduce the generation of cracks in the semi-rigid base,and placing the basalt geogrid in the middle of the semi-rigid base The best results. |
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