Study On Crack Resistance Of Skeleton-Dense Cement Stabilized Macadam Base

China's high-grade highway is developing rapidly.In order to meet the characteristics of high grade highway traffic flow and heavy heavy vehicles,the semi-rigid base of cement stabilized grade is used in high grade highway.The main reason is that the semi-rigid base material has the advantages of high strength,high rigidity and strong carrying capacity,and it has certain anti-bending strength,and the strength also increases with the age.Therefore,the semi-rigid asphalt pavement usually has small deformation and strong diffusion ability.Due to the small bending stress of the face layer,the asphalt layer can resist the fatigue damage of the driving load,and it can be considered that the asphalt layer on the semi-rigid base will not cause the fatigue damage.But there are some problems with cement stabilized graded gravel as the base material.Firstly,the stiffness of cement stabilized graded gravel is much larger than that of the flexible material with asphalt binder.However,the viscoelastic mechanical properties of the cement stabilized graded gravel are not obvious compared with the flexible materials such as asphalt,and it is easy to produce stress concentration in some local defects.However,the defects of materials or structures are unavoidable during the construction process,and these defects also lead to premature destruction of cement stabilized graded gravel.Therefore,it is an urgent problem to study the cause,time and position of the structure of cement stabilized grading gravel.This paper will study at the following aspects:(1)Research on the skeleton dense type drying shrinkage characteristics of size distribution of the cement stabilized gravel,and in-depth analysis of the material factors,process parameters,and environmental characteristics of cement stabilized macadam of drying shrinkage characteristics.In this paper,the effect of the structure composition on the dry shrinkage of cement stable stage is presented.Through the experiment of the system,the design method and general scope of the filling coefficient of the cement stabilized grade with the anti-drying shrinkage are determined.(2)In this paper,the influence of material factors and technological parameters on the temperature shrinkage of cement stabilized grade is studied.In this way,the design principle and technological measure of materials based on temperature reduction are extracted.In this paper,the influence of the structure composition on the temperature shrinkage of cement stabilized stably is presented.Through the experiment of the system,the design method and the general scope of the filling coefficient of the cement stabilized grading gravel based on the temperature reduction are determined.(3)Based on the theory of elastoplastic damage and ABAQUS software,the author has conducted a numerical simulation study on the crack of cement stabilized grading gravel.The results show that the process measures have a significant effect on cracking,and the lateral cracks of about 45m are presented under the action of shrinkage and temperature contraction.Individual thermal shrinkage can cause a certain degree of damage to the base,but it does not lead to lateral cracks.In the case of grass root cracking,its own dry shrinkage has the greatest influence,while the dry shrinkage of bottom layer has little influence on it.(4)Based on the current construction status of cement stabilized gradation stone base in liaoning province,this paper puts forward the test method for the theoretical research results and observe the usage.