Experimental Research On Frictional Sliding Properties Of Rural Isolated Structure Of Sand Cushion

Since the Tangshan earthquake, dozens of destructive earthquakes happened inChina, most of which occurred in the majority of rural and township areas. In2008, the5.12Wenchuan earthquake caused enormous loss to people’s life and property. Theeconomy in the majority of rural and township areas left far behind of it in urban areas.Conditions of casualties and collapse constructions is much more severe than in citiesthat in the rural reaidential areas, towns and villages. All of it is caused by the weakshock tolerance of the public buildings and facilities. Study on seismic tolerance invillage building has become an important topic in China on disaster prevention andreduction.By analysing the structures of the village and town buildings and the destruction inthe earthquake, points out that rural construction problems in the seismic fortification.Through comprehensive analysis of the law of energy attenuation when the wavepropagates in the sand and the theory for seismic reduction as well as it’s advantages,sand cushion isolated seismic technology is recommended for the rural structures.Combinationing with the theory, analysis the mathmatical model and the equation ofmotion of the sand cushion of the isolated structure. In order to clear the frictionalsliding properties of sand, conducting a series of experiments and analyzing the theories.Mainly includes the following aspects:Firstly, the friction coefficient and the frictional sliding properties of differentdiameter sand between the concerte slab are tested. By analysing of the frictioncoefficient, summarizes the influence of the vertical stress to the friction coefficient as well as researches the frictional sliding properties of the different diameter sand.Secondly, analysis of the evaluation method for the seismic isolation structure. Forthe system of particle is different(free and non-free system of particle) and the relativityof particle motion, there will be some probiems when comparing the respongseacceleration and the input acceleration for seismic isolation effect. From the angle of thetransfer path of the force in the sliding system, the rate of momentum change analysismethod of seismic isolation effect is pointed out.Finally, using the shaking table test the sand cushion with the different size anddifferent thickness for clear the frictional sliding properties. Input energy of all types ofsand cushion in different sizes of three kinds of seismic waves. Building structures arereplaced by the rigid block, the sand cushion shows relative sliding which coulddissipate the energy of seismic energy through friction under earthquake. In the sametime, stress leads to deformation, which could also consume the energy by internal sandgrains friction. The results show that lager single size sand has a better isolating effectand the effect signifiantly increased with the increase of the thickness of the sandcushion. As well as the effect of internal energy dissipation is more obvious.Therefore, a certain size sand with the smaller friction coefficient as the cushion isrecommended to use the bigger thickness.