Controlling Mechanism Of U-steel Frame Buckling

Combined support with U-steel beam is the main supporting mean in softfragmentized surrounding rock roadway with high in-situ stress. The frame deformingfeatures include2D bending and breaking in the frame plane, also twisting in space. Thereare many breaking beams phenomenons induced by structural instability, longitudinalloading, or eccentric loading. However, the existing2D model is incapable of explaingU-steel beam longitudinal deforming. Constructing3D beam model and analyzing itsmechanism is the requirements of deepening the research on beam, especially for bucklingbeam. The buckling mechanism is of significant value for buckling controlling measures,and for its support capability assessment.After investigating most beam breaking situation in Huainan, Huaibei, and Kailuanmining areas, the article sums up and classifys it to7types:2D Structural overloadingbending breaking, axial fracture induced by big axial force, longitudinal twisting, tearingdamage on lap point, cable band failure, and integrated breaking. The fore4types are allbuckling types. The frame internal forces distribution law is researched by ANSYS12.13D model with BEAM189. The results of the modeling indicate that internal force extremepoint position on frame and its value are all greatly influenced by constraint types, framearea, span-to-height ratio, and loading method.A U-steel beam loading test is designed to check its main elastic and plastic mainphysical parametrics including Poisson’s ratio, stress limit and tangent modulus. FLAC3Dis applied in this article to study the mechanical function of support and surrounding rock.A new3D model is constructed by SOLID45in ANSYS in order to simulating the frameistability and exploring beam buckling mechanism. In conclusion, the mechanism is putforward from mechanical properties and mechanical sources in the article.The main measures are analyzed in Capter5, which consist of optimization of U-steelframe specification, backfilling behind support, structural reinforcement with bolt andcable on weakness, lag grouting. According to the research results, the appropriatemeasures for frame buckling are practiced in two representative condition soft roadways.There are109figures,22tables and149references in the articale.