Study On Material Pressure Of Retaining Wall In Strip Yard Based On Model Test

China is in a period of rapid industrialization.Metallurgy and thermal power is important industries in the construction process.The construction and development of these two industries are in great demand for industrial raw materials such as coal materials and crushed stone materials.At present,in the condition of using the strip stockyard to preserve raw materials,the retaining wall plays a role in supporting the pile material and separating the space in the strip stockyard.The material retaining wall is the main structure of the strip stockyard,but the building volume is huge and the construction cost is high.Under the condition of ensuring structural safety,the economic efficiency of the reasonable optimization of the retaining structure design is remarkable.Due to the influence of the strip material loading and reclaiming process,there is a big difference between the retaining wall and the conventional slope supporting structure,which is mainly reflected in the limited range of packing behind the wall,the polyline slope,the non-cohesive bulk material,and the filling process pile.The material movement state is complicated.It is impossible to directly solve the material pressure acting on the retaining wall by using the classical soil pressure theory directly.Based on the above problems,this paper uses laboratory model tests for two common materials,such as crushed stone and coal,and combines theoretical analysis and numerical simulation to study the pressure on material retaining wall of strip stockyard.The main research work is as follows:(1)The complexity of the mechanical properties of non-cohesive granular materials and the large differences among different types of materials was analyzed.Through a series of lab tests such as large-scale coarse-grain soil direct shear test and screening test,the physical and mechanical properties of stone and coal materials are tested,including density,repose angle,particle gradation and shear performance.The research on the pressure of the strip material wall material provides basic data support.(2)Contrasting and analyzing the structural differences between the material retaining wall and the conventional buttress retaining wall,simplifying the longitudinal wall stress model to plane strain problem according to the large spacing of the cross wall of the retaining wall and the small constraint on the middle of the longitudinal wall.Based on the existing calculation method of special slope soil pressure,the research method of slope soil pressure calculation theory under special circumstances is proposed.(3)Based on the principle of static balance of the sliding wedge behind the retaining wall,the relationship between the material pressure and the crack angle of the fillings behind the wall is established,and analytical solution of active material pressure in material retaining wall is obtained by seeking limit.(4)Calculating the stress state of any point inside the stack through the natural accumulation of infinitely long triangular prisms model.Comparing the existing calculation model with the static material pressure calculation model on the strip stockyard material retaining wall,proposing a theoretical calculation formula for calculating the static material pressure of the strip material stop wall.(5)Using Abaqus finite element analysis software to establish the three-dimensional strip yard retaining wall structure and stocking model,reasonably selecting the calculation parameters,and establishing the contact between the stack and the retaining wall.Considering the interaction between the stack and the structure as well as the coordinated deformation,the distribution characteristics of the material pressure on material retaining wall in the three-dimensional state are obtained,which provides guidance for the design of the lab model test.(6)As for the accuracy problem of small-scale pressure test of lab model,the calibration method of strain-type micro soil pressure box is improved,and the piecewise fitting function of strain-type micro-pressure box pressure with strain is calibrated.Based on the similarity principle,the lab model test of the strip stocyard is designed.Firstly,the conventional horizontal slope and special strip stockyard slope stack test is carried out,the reliability of the model test results is verified by comparing the results of the conventional horizontal slope test with the existing theoretical calculation results.According to the functional requirements of the material retaining wall,during the test process,different pressure distribution of crushed stone,coal and different sections is obtained by changing the fillings and section forms during the test.(7)By comparing the theoretical calculation with the model test results,the calculation method of the material pressure of the material retaining wall is proposed.According to the distribution characteristics of the material pressure obtained by the model test,the material pressure distribution form of the material retaining wall is adjusted to make up for the defects in the theoretical calculation method,so that the theoretical calculation method can accurately reflect the actual force of the retaining wall.