Research On Shear Bearing Capacity Of Waste Rubber Tire Hooping Granular Material Foundation

At present,the number of passenger cars in China is the highest in the world,and a large number of rubber tires are discarded every year,which forms a huge environmental pressure.At the same time,there are still huge differences between urban and rural areas and eastern and western regions.Therefore,in backward rural areas,due to the limited economic conditions and backward design concepts,the self-built houses of large number of farmers lack anti-seismic design and anti-seismic construction measures.As this kind of building suffers from the earthquake,it would happen either walls cracking or the house collapse.Taking the Wenchuan earthquake as an example,the cumulative economic losses were 845.2 billion,and the number of casualties was over 100,000.In view of this,this paper has established the concept of a constructional foundation of tire ring-hoop bulk material of abandoned rubber.A complex material composed of rubber tires and bulk materials,as elastic elements,rubber tires have the ability to convert the external input energy into their own elastic potential energy,while the friction between particles of the bulk materials can transform mechanical energy into internal energy for dissipation.Thus the complex has potential energy dissipation and shock isolation characteristics.In order to apply this type of constructional foundation to village and town buildings,and to simplify the anti-seismic design of village and town buildings,to improve the anti-seismic performance of the self-built houses of the peasant households.This paper has studied the anti-shear performance of the sample of three-layer single column,and the hysteretic energy dissipation capacity of the sample,and the mechanical behavior of the foundation model under the low-cycle load.According to the above three aspects:Firstly,it was carried on the double shear test of the sample.The study found that the three stages of the shearing destroy,namely,the overall flexural and side shift,the horizontal compression of the test unit,the relative slip between the interface of the unit body.The load-displacement curve is approximately three fold lines,which is mainly caused by the elastic creeping between interfaces.Under the long-term load,when load levels are approaching the peak,the horizontal displacement of the sample is constantly increased,which be destroyed because of noncoverage.It finally result in the anti-shear strength envelope of the sample and the uniform expression of the constitutive equation of the rising segment of stress-strain curve of every vertical forces.Secondly,it was carried out on iterative loading test of the sample.The study found that the hysteretic curves of the sample under each vertical force condition are very full,indicating that the sample has good energy dissipation capacity,which makes it possible to further study the whole anti-seismic performance of the constructional foundation.With the increase of vertical force,the initial stiffness,yield load and peak load of the sample are increased correspondingly,and the skeleton curve stretched upward trend.In order to counteract the effect of the different axial forces on the skeleton curve,the skeleton curve was treated dimensionless.After processing,all the curves tended to be consistent,which was easy to describe in a uniform mathematical expression.When the sample yielded,the stiffness degradation velocity of the initial stage in the state of the high vertical forces was faster than that in the state of the low vertical forces,and then they tended to be consistent.Due to the large initial stiffness of the sample in the high vertical force state,coupled with the degenerative velocity and other factors,in the same horizontal displacement,the residual stiffness of the sample was larger.The contribution of vertical force to residual stiffness in high vertical force state was large,which indicated that the vertical pressure in the work of the sample was conducive to improving the ductility of the building foundation.The damping ratio decreased with the increase of the vertical force before the yielding of the samples.When the sample yielded,in the same horizontal displacement,the damping ratio of every vertical forces trended to be consistent.Finally,the mechanical behavior of the foundation model was studied by the low-cycle test.The study found that the horizontal bearing capacity and the anti-lateral stiffness of the foundation would be improved by using staggered joints.With the increase of the staggered dimension,the shape of the hysteresis loop of the composite foundation was transformed from a long and thin fusiformis to a plump apricot kernel,the degree of fullness of which increased significantly.The shape tended to counter clockwise rotation,and to certain extent,the horizontal bearing capacity and the lateral stiffness of the composite foundations were all increased.The growth rate of horizontal bearing capacity was 29.9%and 42.1%,and the growth rate of lateral stiffness was 44.8%and 98.2%.The method of adding fiber mesh can also improve the horizontal bearing capacity of the foundation,but it would weaken the initial stiffness of the foundation.Carbon fiber mesh was laid by a state of relaxation within the interface between the layers of composite foundation,to some extent,it weakened the connection between the two layers of the sample,making a drop in the initial lateral stiffness of constructional foundation;With the increase of the horizontal displacement of the constructional foundation,the fibers in the mesh are tensioned,and the reinforcing effect of the carbon fiber mesh on the whole construction of the foundation began to improve.With the improvement of the whole structure,the horizontal bearing capacity of the foundation is improved and the anti-lateral stiffness of the foundation is reduced.