| Due to the high standard requirements of high-speed railway,the micro expansion deformation of subgrade also causes great harm to the smoothness of the line.Some open high-speed railway lines also have a lot of camber diseases,which brings great difficulties to the operation and maintenance.Therefore,the micro expansion problem in the construction of high-speed railway should also be paid attention to.The control of micro expansion deformation is not only a problem of control standard.In order to ensure the economy and science of engineering construction,it is necessary to carry out systematic research on the occurrence,development process and law of micro expansion deformation.It is strictly forbidden to use expansive filler in subgrade engineering of high-speed railway.However,in some areas,the non expansive mixture inevitably contains certain proportion of expansive material,and its actual expansion deformation performance is different,which has caused great trouble to the engineering construction.It is necessary to master its expansion deformation law and analyze its harm systematically.In this paper,based on the investigation of high-speed railway foundation arch diseases such as Shanghai Kunming railway,Beijing Shenyang Railway,Lanzhou Xinjiang Railway and Daxi railway,through laboratory tests and PFC particle flow numerical simulation,the macro and micro expansion deformation characteristics of the mixed filler containing expansive components are analyzed;the expansion mechanism of the micro expansion mixed filler is revealed;the expansion mechanism model of the mixed filler containing the expansive component is established;and the micro expansion mixed filling is proposed Test and evaluation method of material expansibility.Mainly carried out the research of the following contents and reached the following conclusions:(1)Through laboratory tests,the physical,chemical and expansion characteristics of the expansive components in the mixed filler are obtained.A large diameter multi ring dilatometer is developed to analyze the micro expansion influencing factors and expansion rules of the mixed filler.Among them,the expansion component content,initial water content,load and porosity have great influence on the micro expansion deformation of the mixed filler.(2)Through PFC3 D particle flow numerical simulation software,the meso model of expansive component mixed packing with different content,coarse particle shape uniformity and different porosity was established.The particle movement characteristics,contact force chain,pore change and energy evolution law of the mixed filler were obtained.The expansion process of the mixed filler containing expansion component was the water absorption volume of the expansion component and the bone filling The macro expansion process of the framework pore and the uplifted skeleton is formed.(3)Based on the mechanism that the expansion volume of expansive component is transformed into the pore volume of filling and the macroscopic expansion volume of skeleton uplift,the expansion mechanism model of mixed packing with expansive component is established.Based on the principle of minimum energy,the distribution equation of pore and uplift skeleton of expansive component and the calculation formula of expansion rate of mixed filler containing expansive component are established.(4)The pore plate tester with equivalent pore size of mixed packing framework was developed to simulate the process of expanding component filling pore and the energy consumption through the pore.The evaluation method of expansive property of micro expansive mixed filler is put forward,which is based on the test of expansive component,energy consumption of expansive filling and void state test of non expansive skeleton. |
