| SMW construction method,as a foundation pit support structure often used in construction projects at home and abroad,has the characteristics of good overall structure,high anti-seepage performance,wide applicable stratum,environmental protection during construction,and low construction cost.For SMW construction method,whether the section steel can be recycled normally and effectively after the construction is completed directly affects the economic benefits of the project.There are still deficiencies in the research on section steel pulling and recycling,anti-friction materials and standardized experiments.This paper is mainly based on tribology,structural mechanics of composite materials,and elastic mechanics,research on the force of section steel pulling process,the interface relationship between section steel and cement-soil,the formula of pulling force of section steel,new antifriction materials.The main contents are as follows:(1)Introduce the development of tribology and related friction characteristics to provide a theoretical basis for the analysis of the interface between section steel and cement-soil.The crawling phenomenon in the process of section steel pulling is elaborated,and the factors affecting the crawling phenomenon and the mechanism of the influence are analyzed to provide theoretical support for the development of friction reducing agent.(2)Explain the mechanism between the two composite interfaces of section steel and cement-soil,analyze the factors that affect the bonding performance between materials.The process of steel pulling is classified into stages,and the mechanism of detachment between steel and cement-soil during pulling is analyzed.Based on the interlayer stress of the composite material,a simplified analysis of the section steel cement-soil model was carried out,and the relationship between the normal stress and the shear stress between the section steel and the cement-soil interface was obtained.(3)Based on the Mindlin displacement solution,the section steel Sectional area is simplified as a steel pipe pile,and the distribution formula of the section steel surface axial force during the pulling process is deduced.The equation for the estimation of the pulling force of the profile steel is derived based on the elasticity theory and tribological properties.(4)The anti-friction materials used for section steel are bituminous substances,which cause serious environmental pollution.There is a lack of research on anti-friction agents.the new friction reducing materials with paraffin wax,petroleum jelly and rosin as the main additives were identified through four tests,including trial formulation test,main additive test,orthogonal test formulation test and large size experiment,with a total of more than 40 experimental groups,and a model test was conducted to compare the pulling force.It is concluded that the newly developed anti-friction materials are better than the original ones Mount material. |
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