Research On Fatigue Performance Of Reinforced Semi-rigid Base Pavement

Semi-rigid base has been widely used in China’s high-grade pavement structure because of many advantages such as strong load-bearing capacity,good durability and high stability.With the increasing traffic volume and load,the fatigue performance of the semi-rigid base layer is insufficient resulting in premature cracking,rutting and other structural damage,which significantly reduces the service life of the pavement.At present,most of the methods are used to improve the fatigue performance of semi-rigid subgrade by optimizing the grade design,reasonable cement dosage and controlling the construction quality,but the improvement effect is not ideal.In this paper,we start from the idea of actively improving the force state of semi-rigid base,and draw on the idea of setting reinforcing steel in structures and bridge deck pavements to lay reinforcing materials in semi-rigid base.The fatigue cracking of semi-rigid subgrade is slowed down or inhibited by the effective bonding of subgrade materials and reinforcing materials,and the fatigue performance of semi-rigid subgrade is enhanced.To provide new ideas and methods for extending the service life of pavement.Based on the above theoretical basis,considering the actual stress state of the pavement,three reinforcing materials,namely,steel wire mesh,pultruded plastic grating and glass fiber grating,formed cement stabilized gravel slab type specimens,and rubber sheet as the support,were selected to design a two-way stress-supported fatigue test method based on MTS for semi-rigid subgrade materials.Weibull distribution theory model was used to regress the support fatigue test data,and a fatigue prediction model for reinforced semi-rigid subgrade materials was established.In this paper,the effects of reinforcement material,reinforcement location and number of reinforcement layers on fatigue life and fatigue cracking of semi-rigid base materials were studied,and it was found that the effect of extending fatigue life and retarding fatigue cracking after reinforcement was very obvious.The fatigue resistance of the reinforced base material of the pull-plastic grid is the best,and the location of reinforcement should be laid in the middle and lower part of the base,and the number of reinforcement layers should be laid in a single layer.The fatigue cracking characteristics of reinforced semi-rigid subgrade materials are summarized by close observation of fatigue cracking of cement stabilized gravel slabs.In this paper,the fatigue strain test was designed and carried out on the basis of the support fatigue test,and the strain development law of the reinforced semi-rigid base material was derived.The determination methods of strain stabilization increase turning point and ultimate strain point are proposed,and the initial strain value,strain turning value and ultimate tensile strain value of reinforced semi-rigid subgrade materials are derived.It provides a scientific basis for the practical application of reinforced materials in the fatigue resistance of semi-rigid subgrade pavements.