Design Of Dynamic Load Direct Shear Test System Of Frozen Soil

With the continuous advancement of engineering construction in permafrost area and the increasingly extensive application of artificial freezing method in urban underground engineering,engineering problems related to frozen soil are increasing,especially the stability problems of frozen soil under the dynamic loads caused by construction and earthquake,at present,is a hot topic and cutting-edge course in the field of Frozen soil mechanics and Engineering.For a long time,advanced test instruments are effective means to accurately grasp and reveal the mechanical properties of frozen soil and promote the development of the theory and practice of frozen soil mechanics.Many classical theories of frozen soil mechanics are based on the test results.On the other hand,the increasing demand for mechanical properties test of frozen soil with complex stress and temperature boundary conditions is also promoting the continuous improvement and innovation of experiment technology and test methods.Therefore,based on the actual needs of dynamic shear test of frozen soil and the advantages and disadvantages of existing direct shear apparatus,this paper plans to develop a high-performance dynamic load direct shear test system of frozen soil,which can also realize the temperature control of large-scale frozen soil samples and the simulation of different freeze-thaw cycles and normal stiffness and other boundary conditions.The research of the whole dynamic load direct shear test system of frozen soil,including bearing platform,dynamic load control,data acquisition and other functional modules,involves mechanical,measurement and control,geotechnical and other interdisciplinary content,the details are as follows:(1)Function and basic parameter design of the direct shear test system of frozen soilBased on the analysis of the requirements of dynamic shear test and the research status of dynamic load in practical application,the functions and basic parameters of the proposed test system are determined,and the selection of the main functional modules of the system is completed.(2)Mechanical system design and manufacture of the direct shear test system.On the basis of summarizing the advantages and disadvantages of existing direct shear apparatus,the design and manufacture of shear box of dynamic load direct shear test system of frozen soil,load bearing vibration platform,hydraulic pump station are completed.The size of frozen soil shear box is 300 mm × 300 mm× 220 mm,the dynamic load frequency is 0?6 Hz,the maximum shear force is 20 KN,the maximum shear displacement is ± 50 mm.(3)Servo control strategy and virtual simulation of the direct shear test systemAccording to the overall design of the control system,the mathematical model is built in Simulink,and the control strategy of the system is studied and simulated.(4)The upper and lower computer design of the direct shear test systemThe upper and lower computer software of the dynamic load system is designed.The upper computer software is designed based on Lab VIEW,and the lower computer software is designed based on x PC Target rapid prototyping technology.(5)Test of the direct shear test systemThe preliminary test is carried out by using the developed dynamic load test system of frozen soil.The dynamic load loading performance of the test system,the shear box function of frozen soil samples and the accuracy of data measurement system are systematically inspected.The function,achievement degree of performance target and overall reliability of the test system are analyzed.This thesis includes 84 figures,13 tables and 68 reference.