Numerical Simulation Study On Mechanical Properties Of Waste Rubber Tire Foundation

The number of cars in China is increasing year by year,which produces a large number of waste tires,but the recycling rate is very low,causing serious "black pollution".At the same time,China is one of the countries with more serious earthquake disaster,especially in villages and towns.In view of the above two backgrounds,this paper proposes a kind of waste rubber tire structure foundation which is suitable for village buildings,in order to achieve the purpose of earthquake resistance and waste reuse.In order to explore the mechanical properties of waste rubber tire foundation,the following three aspects are studied in this paper,and the following conclusions are obtained:(1)Based on the laboratory test,a numerical model of single bundle cylindrical composite of waste rubber tire and bulk material is established.Through theoretical analysis,the appropriate model parameters are selected for reasonable simplification.Through the analysis of stress and deformation results,compared with the test data,crushable is verified The foam plastic constitutive model is feasible for the definition of sand plastic constitutive model,and has high application value in the analysis of complex contact and highly nonlinear dynamic display algorithm;it verifies the rationality of model parameter setting,provides the basis for the establishment of the numerical model of waste rubber tire construction foundation,and ensures the calculation accuracy and credibility of the simulation results of the numerical model of construction foundation.(2)According to the actual situation of the village and town buildings,the typical working condition of the structural foundation is designed,the full-scale structural foundation numerical model is established according to the parameters of the composite model,and the vertical bearing capacity and seismic performance of the structural foundation are analyzed.By comparing the load settlement curve between the structural foundation and the natural foundation,we can get the critical plastic load and the ultimate load of the structural foundation,and get the conclusion that the ultimate bearing capacity of the structural foundation is about 60% higher than that of the natural foundation.The actual temporary plastic load of the structural foundation is less than the temporary plastic load;the vertical additional stress of the inter tire soil is less than that of the inner tire soil,with an average value of 0.8-0.9 times of that of the inner tire soil;the compactness of the inner tire soil is greater than that of the inter tire soil,with an effective internal friction angle of 39-42 ° and 30-38 ° respectively;the structural depth is the main factor affecting the stress diffusion angle,and the greater the structural depth is,the greater the stress diffusion angle is,with a range of 45-65 °.It is proved that the larger the vertical load is,the greater the initial lateral stiffness of the structural foundation is,the greater the horizontal ultimate bearing capacity is,the deeper the horizontal load is transferred downward,the stronger the energy dissipation capacity is,and the better the seismic resistance performance is.However,when the vertical load does not reach the real critical plastic load,the overall ductility of the structural foundation is better.(3)On the basis of the existing basic theory of the ultimate bearing capacity of the foundation,the formula of the ultimate bearing capacity of the construction foundation of the waste rubber tire is derived theoretically,and the calculation formulas of the ultimate bearing capacity of the construction foundation with three different methods are obtained respectively.The error analysis is made by comparing the calculation results of the numerical model,which shows that the calculation results of the formula of the ultimate bearing capacity of the foundation constructed by the modified stress diffusion angle method are biased large and the error is relatively larger;the calculation results of the formula of the ultimate bearing capacity of the foundation constructed by the modified Terzaghi method and variational limit equilibrium method are biased small and the error is relatively smaller.The formula of ultimate bearing capacity of foundation constructed by improved stress diffusion angle method and improved Terzaghi method is modified.Using MATLAB to write particle swarm optimization algorithm to fit the formula modified parameters.The fitting correction parameters are obtained and the fitting results were evaluated.It is proved that it is reasonable and feasible to use particle swarm optimization to fit the modified parameters of the more complex formula of the ultimate bearing capacity of the foundation.