Evaluation And Analysis Of Shear Resistance Of Asphalt Pavement Under Incomplete Continuous Inter-layer

Cracking disease has become the main disease type of asphalt pavement.A large number of road surveys have shown that the bonding failure causes inter-layers separate.The failure of the inter-layer bond caused by the inter-layer shear stress will accelerate the cracking of the pavement and reduce life of the pavement.However,most of the current studies are based on the complete continuous or complete sliding state between the pavement layers.In actual conditions,The layers are in a state of incomplete continuity.For this reason,this paper will conduct research on the shear resistance of asphalt pavement under incomplete continuity between layers through finite element calculation and indoor test evaluation.First,establish a finite element model and a fatigue analysis model for the asphalt pavement structure considering the inter-layer gap.The relevant parameters are determined according to the typical pavement structure size and material type of the main road in Beijing.The inter-layer gap is used to characterize the incomplete bonding between the layers.Through model calculation and analysis of the changes in the stress field and displacement field at the tip of the inter-layer gap,it is verified from the perspective of fracture mechanics that the inter-layer shear stress is the main reason for the failure of the inter-layer bond.The stress intensity factor is used to determine the most unfavorable gap point.It is the inter-layer position of the upper-middle surface layer extending vertically downward at the outer edge of the vehicle tire.Then,based on the finite element model and fatigue analysis model of the asphalt pavement structure considering the inter-layer gap,the inter-layer shear stress and the number of shear fatigue of the asphalt pavement are calculated.Refer to the data of temperature conditions and traffic load conditions in Beijing to analyze the influence of different factors such as temperature,car load,brake load,structure thickness,gap length,etc.on the inter-layer shear stress and the number of shear fatigue.The most unfavorable situation The maximum inter-layer shear stressτ≥0.37 MPa,and the number of inter-layer shear fatigue ≥9,395 times are used as the index reference values of the model,and the regression equation is established based on the calculated data.Secondly,evaluate and analyze the shear performance of the adhesive layer material.Four adhesive layer materials commonly used in road construction in Beijing are selected to determine the best coating amount.Conduct shear strength experiments at different test temperatures to analyze the temperature sensitivity of the shear strength of different materials;perform short-term and long-term aging on the adhesive layer materials to study the influence of temperature aging on the inter-laminar shear strength;for the adhesive layer materials perform multiple freeze cycles to explore the influence of freeze cycles on its shear strength.The results show that: the shear strength of the bonding material has high temperature sensitivity;under short-term aging,the shear strength of the bonding layer material is increased,but the shear strength of the bonding layer material under long-term aging is greatly reduced;Comparing the shear strength of the adhesive layer material under different freeze-thaw cycles,it is found that the shear strength of the adhesive layer material decreases the most under the first freeze cycle.Thirdly,the fatigue resistance performance of the adhesive layer material is evaluated and analyzed.Under the conditions of changing the experimental temperature,load level,temperature aging,and freeze-thaw cycles,the shear fatigue experiment of the adhesive layer material is carried out,and the influence of the former on the latter is analyzed.The results show that the temperature has a greater influence on the shear fatigue performance than the load stress level;the shear fatigue performance of the bonding material decreases under both short-term and long-term aging,and long-term aging has a greater impact on it;the first freeze-thaw on the bonding layer material Shear fatigue performance has the greatest impactFinally,based on the data output by the model and the material properties of the indoor test,the inter-layer bonding material that meets the index reference value is recommended.Through comprehensive comparison,it can be seen that the shear strength and shear fatigue resistance of SBS+rubber composite modified asphalt are the best under different conditions.It is necessary to pay attention to the effect of long-term aging;SBS modified asphalt and rubber asphalt are the second,followed by The performance of the two is relatively close.The anti-aging performance of SBS modified asphalt is better than that of SBS modified asphalt;the emulsified asphalt is inferior,and its shear strength at high temperature is lower,and its anti-shearing performance is affected by temperature aging and venting cycles.