| On site core drilling sampling is a simple,intuitive and effective method for pavement performance detection,which is one of the most practical means for road maintenance decision-making.However,the core samples drilled on site are affected by pavement diseases,structural forms,core drilling operations,etc.,and the height of the core samples often can not reach the height of the standard test pieces.The existing evaluation methods can not accurately obtain the mechanical indexes.Therefore,it is very important to study the mechanism of size effect on the mechanical properties of core samples.Based on the combination analysis of indoor test and numerical simulation,and the demonstration of solid engineering test,this paper systematically studies the size effect of the basic mechanical properties of asphalt mixture.The main research contents are as follows:First of all,four types of asphalt mixture(AC-13 matrix,AC-13 modified,AC-16 matrix,AC-16 modified)were selected to carry out splitting tensile test,freeze-thaw splitting test,uniaxial penetration test through the test pieces with the forming height of 30mm,40mm,50mm and 63.5mm in the laboratory.Based on the data fitting algorithm,through multiple data iterations,different test pieces of different sizes,different gradations and different glues were studied Based on the influence law of binder and different void ratio on the mechanical properties of non-standard specimens,the equivalent equation of specimen size and its mechanical properties is derived,and the size effect formula is further derived to fit the size effect coefficient formula of different asphalt mixtures.Secondly,based on the finite element analysis,the stress state and failure mechanism of the specimens with different heights in the splitting tensile test and the uniaxial penetration test are obtained,and the change rule of the height and size effect coefficient of the specimens is obtained,which provides a certain theoretical reference and verification for the indoor test results.Finally,the indoor test is carried out on the core samples obtained from the pavement drilling,and the influence of the size change on the test results is analyzed.The strength of the non-standard test pieces is transformed by the size effect coefficient formula proposed in this paper.The discrete type of the strength value after transformation is analyzed to verify the accuracy of the size effect coefficient formula. |
