Study On Mechanical Properties And Supporting Mechanism Of Anchor Cable With C-shaped Tube

Prestressed rock bolt and anchor cable are important support components in mine support field.With the deep mining of coal resources year by year,the stress environment of prestressed rock bolt and anchor cable is more and more complex,and large deformation roadway is common.For large deformation roadway,it is a mainstream trend to adopt high preload supporting members.With the increase of preload of supporting members,there is a phenomenon that shear bearing capacity decreases,and the proportion of supporting members broken by transverse action in the process of deep roadway support is not low.In this context,the team invented a kind of supporting structure,Anchor Cable with C-shaped tube,which can take into account both high preload and high lateral shear bearing capacity.In this thesis,the mechanical properties and supporting mechanism of the supporting structure are studied by means of numerical calculation,theoretical derivation,experimental study and industrial experiment.The main work carried out and results achieved are as follows:Based on the theory of elasticity and coulomb criterion,the thesis deduces the scope of transverse action of roadway roof,and establishes the applicable scope of C-shaped tube.According to FLAC3 D numerical simulation software,the PILE element was used to simulate the rock bolt,and the PILE element was used to apply the PILE element to simulate the rock bolt preload.The mechanical behavior of prestressed rock bolt shear by structural plane under different conditions is simulated.The deformation and stress law of bolt segments under shear of supporting member under different factors are discussed.The influence of transverse action of structural plane on supporting member is studied.The countermeasures to prevent transverse fracture of supporting member are obtained.The design concept of Anchor Cable with C-shaped tube is introduced.In the form of theoretical derivation,the supporting mechanism of Anchor Cable with C-shaped tube is discussed from two aspects of transverse and axial.Based on Coulomb theory,deformation energy theory and classical beam theory,the three stages of stress before sliding,before closing and after closing under the transverse action of structural plane are analyzed.The quantitative relationships between shear strength and material,surrounding rock parameters and stress state and displacement state are obtained.The criterion of failure of Anchor Cable with C-shaped tube was obtained through Mises yield criterion.The single supporting mechanism of high preload Anchor Cable with C-shaped tube is discussed by elastic boussinesq solution.The Angle point method and the superposition principle of boussinesq solution are used to explain the supporting mechanism of the coarrangement of Anchor Cable with C-shaped tube,and the supporting mechanism is verified by the numerical simulation software FLAC3 D.In order to eliminate the influence of normal pressure and friction between structural planes on the behavior of structural plane shear supporting members,a set of non-friction tension and shear equipment for double shear supporting members was developed independently on the basis of common instruments that can be used to study the shear performance of supporting members,namely tension and shear system of anchor cable(bolt)and c-shaped tube.The pre-tightening force is applied to the supporting member in the form of the lock to pull the supporting member,so there is no normal force between the structural planes and no friction force between the joint planes.After removing the normal force and friction force,the measured shear force is pure shear force.The equipment was used to carry out tensile test and tensile shear test against different supporting members in Anchor Cable with C-shaped tube.The tensile and shear bearing capacity of different supporting member foundation in Anchor Cable with C-shaped tube is tested.At the same time,tensile and shear tests of rock bolt and anchor cable under different preload conditions verify that the shear bearing capacity of supporting member decreases correspondingly under high preload conditions.The tensile and shear performance of the whole structure was tested by tensile and shear tests after the supporting members were composed of Anchor Cable with C-shaped tube structure.The shear bearing capacity of Anchor Cable with C-shaped tube under different preloading force,different internal material and different anchoring mode was studied experimentally.The results show that the shear bearing capacity,shear deformation resistance and axial bearing capacity of the internal support members of the C-shaped tube are greatly improved.The weaker the internal supporting member is and the higher the initial preload,the higher the shear bearing capacity is.A field investigation is made on the roadway near 3210 timber lane in Nanguan Mine.In view of the problems of large deformation of surrounding rock and frequent breakage of rock bolts and anchor cables in 3210 roadway of Nanguan Mine,the surrounding rock structure survey was carried out on site.It is concluded that the main reasons for the deformation and failure of 3210 timber roadway in Nanguan Mine are as follows: the support range is smaller than the thickness of loose surrounding rock,the preload setting is too small,and the deformation control ability of surrounding rock is weak.The use of steel ladder beam with too low stiffness results in the independent action of supporting members,which can not form a high stiffness collaborative supporting system.The surrounding rock of the roof is broken and deformed too much,and the cable is damaged by the combination of tension and shear.Based on the theory of reinforced arch and thick anchor plate,the full-section Anchor Cable with C-shaped tube support scheme was designed and put forward by theoretical calculation and numerical simulation.A 200 m support test was carried out at the site and continuous mine pressure monitoring was carried out at the site for two months.The monitoring results show that through the high preload and high shear performance of Anchor Cable with C-shaped tube,the problems of large deformation of surrounding rock and multiple tensile and shear fracture of supporting members of 3210 roadway in Nanguan Mine are solved.It provides another reference method for supporting design of roadway under similar working conditions.