Static And Dynamic Characteristic Analysis Of Rubber Sand Mixture And Its Application On Base Isolation

In recent years,people's production and life suffered huge damage in the frequent earthquakes such as the Wenchuan,Yushu and Ya'an earthquakes.In particular,a large number of low-rise buildings in the villages and towns have been severely damaged by previous violent earthquakes,resulting in massive casualties and property damage.However,the existing isolation methods are often expensive and only used in some important buildings,which are difficult to popularize in village buildings.Therefore,it is very necessary to study the cheap vibration isolation methods that can be applied to common buildings.Second,the rapid development of the automotive industry has made waste tires one of the major solid wastes in the society.How to efficiently and profitably use waste tires has become a serious issue.This paper presents a kind of mixture called RSM for short,which is mixed waste rubber granules with sand by a certain proportion as a base isolation cushion material.Its basic mechanical properties were studied by laboratory tests(static and dynamic)and discrete element numerical simulation,from which various mechanical parameters of RSM were acquired.And then its isolation effect and mechanism as a distributed isolation system were studied.The main research contents and works are as follows:1.With the summarization of lots of interrelated references,the study actuality and developing level which about cheap isolation method and static and dynamic characteristic of RSM are presented.The limitaions,advantages and disadvantages existing in research work are discussed too.Then further solutions and research iders for related issues in this paper are introduced.2.Based on static triaxial shear tests and cyclic simple shear tests,the stress-strain relationships,strength & deformation characteristics and dynamic properties of RSMs were studied.The influences of the factors such as mix ratio,particle size ratio,confining pressure,vertical stress and geo-grid reinforcement were taken into accounted in tests.The mechanism of the shear strength and modulus change of RSM are analyzed according to the experimental phenomena,and its quantitative analysis results of static and dynamic characteristic were obtained.3.Based on a series of mesoscopic simulation experiments were conducted by particle flow code,the influences of the particle size ratio and mix ratio of two base materials on the meso-and macro-mechanical behavior of RSM were studied.Based on the discussion of particle rotation,force chain structure and energy dissipation law of the mixture sample,the meso-deformation mechanisms of RSM are explained.4.The simple shear tests are conducted to study the shear properties of RSMstructure interface by using the improved cyclic simple shear testing system.In these tests,several factors that may have effects on the interface behavior are studied carefully,such as structure materials,interface roughness,the vertical pressure on the interface,and the shearing with unilateral or cyclic loading.The mechanical properties of contact surfaces under different conditions were revealed.Analysis results can provide experimental basis for further study on the characteristics of the contact surface and stress-strain calculation between RSM and superstructure under earthquake action.5.The vibration isolation performance of RSM cushion and GGRSM cushion(geocell and geo-grid composite cushion)under seismic wave was studied by means of shaking table test,in which the masonry structure with large stiffness was replaced by the rigid mass block.Test results indicate that GGRSM composite cushion has good isolation effect.Larger sand particle size means better vibration isolation effect,and the earthquake-reduction coefficient is more influenced by the base pressure and input acceleration.Compared with the existing literature,in general,the isolation effect of reinforced RSM composite cushion is better than that of pure RSM cushion,which can be used as a feasible method for the isolation of low-rise buildings in rural areas.Finally,the methods and standards of seismic isolation in the current seismic codes in China are discussed,and the main means for existing simple earthquake isolation studies are summarized and compared.For the method of this paper,the empirical formula of isolation effect is given,and the promotion economy of the composite cushion is analyzed.