Overall Design And Structural Analysis Of Subgrade And Pavement Mechanical Property Test Device

The bearing capacity of subgrade and pavement determines the road quality level.At present,the parameters with important engineering application value for the design,construction quality control and maintenance decision of subgrade and pavement are mainly deflection value and resilience modulus.Aiming at the shortcomings of the existing subgrade and pavement deflection and resilience modulus testing equipment,a new subgrade and pavement mechanical property testing device is designed.The device has the advantages of short transmission path of loading reaction force,threedimensional space movement,and can realize the joint testing of dynamic and static deflection and resilience modulus.The main research contents of this paper are as follows:(1)Overall design of subgrade and pavement mechanical property test device.According to the test site conditions and the technical indexes to be achieved by the function of the loading device,this paper provides two design schemes and compares them.Finally,the design scheme of gravity bearing structure is determined,and the structural components and key technologies of the scheme are introduced in detail.(2)Static analysis of main structure of subgrade and pavement mechanical performance test device.The static analysis of each main structure is carried out by using finite element technology,and the stress nephogram and deformation nephogram are obtained.The results show that the stress of each main structure is less than the yield strength of Q345B material,and the deformation is small.Therefore,the structural design and material selection of the loading device meet the requirements of strength and stiffness design.(3)Overall modal analysis of subgrade and pavement mechanical performance test device.The first eight natural frequencies and vibration modes of the subgrade and pavement mechanical performance test device are extracted by finite element technology.The results show that the natural frequency of the whole device is not within the dynamic loading excitation frequency of 0～15Hz,which meets the requirements of dynamic design.(4)Installation and commissioning of subgrade and pavement mechanical performance test device.Complete the installation of parts of the loading device,and debug its basic functions and dynamic and static loading forces.The results show that the loading device operates normally,and the dynamic and static loading forces can reach the preset value,and the loading accuracy can meet the design requirements of 1kn and 0.5kn respectively.In addition,in order to further understand the vibration characteristics of the whole equipment,a vibration signal acquisition platform of the test device is built.The results show that the reaction force transmission path of the loading device is short,and the vibration energy at the bottom beam is effectively reduced.The new loading device developed in this paper can quickly and accurately complete the measurement of subgrade and pavement deflection value and resilience modulus,which is of great significance in the evaluation of road bearing capacity,and also provides a reference for the research and development of similar equipment.