Study On Crack Propagation Mechanism And Application Of Large-Size Aggregate Interlocking Materials

Cracking of cement stabilized macadam is an important cause of pavement damage of semi-rigid base in China.If large-size aggregate(12-18cm)is used as the main aggregate and cement filler is used to fill the gap between the main aggregate,the large-size aggregate interlocking material can be formed.The main aggregate can be used to form a space crowded structure with larger friction and crowding force.It can also cut off the connection between filling fine materials to a great extent,avoid continuous slabs similar to semi-rigid base,delay and hinder the upward propagation of cracks.Firstly,the material design of the pavement with water-stabilized filling large-size macadam base is analyzed.Considering the shortcomings of water-stabilized material as filling material,such as many construction procedures,high manual dependence and unstable locking degree of large-size gravel,this paper improves the design of filling material.The elastic modulus,compressive strength,flexural strength and crack growth pattern of the self-compacting filling material were tested by laboratory tests.Secondly,aiming at the characteristics of large size aggregate interlocking materials,random aggregate delivery is realized.Then,combined with the bilinear cohesive zone constitutive model,a micro-finite element fracture model is established by inserting three-dimensional zero-thickness cohesive interface element between aggregate-filler interface and filler.Dynamic cracking simulation analysis of selfcompacting large-size gravel material was completed by local loading through ABAQUS.The meso-fracture analysis shows that the interface between aggregate and filler is the weak phase of material,and the fracture extends from the interface.Increasing the particle size of coarse aggregate and controlling the morphological characteristics of coarse aggregate can effectively enhance the overall bearing capacity and crack resistance of aggregate-locked materials.The sensitivity analysis of the aggregate-filler interface shows that the interfacial bond strength has a greater impact on the crack resistance of the material,while the sensitivity of the interfacial fracture energy parameters is weaker.Further three-dimensional dynamic cracking simulation shows that the crack morphology of two-dimensional dynamic cracking is highly consistent with that of two-dimensional dynamic cracking,and the critical load of fracture and damage energy consumption are close to each other.In the end,the pavement structure design of S311 provincial road with waterstable filling large-diameter macadam base test section in Zhongxiang City of Hubei Province is checked and calculated.The results show that the large-diameter aggregate interlocking material base pavement can well adapt to heavy traffic flow,has excellent anti-cracking effect and bearing capacity,and can be used as an important choice of pavement base material.