| Geotechnical anchoring, as a kind of practical engineering technology, is one of the mosteffective methods to solve the stability of geotechnical engineering problems. It is widelyused in slope, tunnel, mining, foundation ditch and so on. Due to anchoring system belongingto hidden and complex project, the theory of anchorage is un-mature so far. The mechanismof it doesn’t have a complete system, and the anchor design and construction also have someblindness. Based on the analysis and summary of present researches and existing problems ofanchoring situations, anchoring failure modes and anchorage mechanism on interface, deepresearches were carried out and the main work is as follow:(1) Summarizing the existing shear slip model between the anchorage and therock,based on the shear slip model of pore wall which was built by B.Benmokrane, taking theload transfer function method, a elastic-plastic model was set up for the theoretical solution ofthe shearing stress distribution law along the length direction. Research shows that anchorsolid rock interface can be divided into the residual shear stage, plastic softening stage andelastic deformation stage, and the different stage of interface has different shear stressdistribution. And the factors which influence the anchoring effect were analyzed exactly.(2) The differential equation for the interactions between bolt (cable) and rock was set upand based on the shear slip model in elastoplastic state and viscoelastic plastic state theinterfacial stress distribution were obtained. Combined the drawing model, the shear stressand the axial force of the pre-stressed anchor (cable) were deduced and the method ofreasonable pre-tension load was given.(3) Based on steel surface, the dilatancy sliding model was introduced into the interfacestress analysis. The load transfer model was built in mortar, the axial force and shear stressdistribution along anchorage were obtained and the factors were analyzed. Use the elastic theory of anchor (cable) reasonable aperture ratio analysis, the formula for aperture ratio wasobtained.(4) By the experimental study of bolt (cable) in rock and loess, the test results were ingood agreement with the theory analysis results that the stress distribution along theanchorage. Obtained the failure processes of two interfaces based on the analylzed the wholeload-displacement curves of the bolt (cable) pulling test in coal and mortar and used theacoustic emission technique made systems analysis of the failure processes on interface inmortar. Derived the ultimate pull bearing capacity calculating formulae of anchorage systemunder the cone-bond destruction mode, obtained the ultimate pull force of steel when appearcone-bond destruction appeared in the process of test, and compared with the theoreticalvalue.(5) The formula relationship between the limit shear strength parameter of anchoringlayer interface and the bolt P-S curve was derived. By the P-S curve datas of field anchor testsin the coal mass, obtained the shear strength parameters between the resin and coal mass, hasguiding significance to direct bolt (cable) engineering design.(6) Based on the theory and experiment on anchorage，a dynamic bolt (cable) designmethod which in line with the engineering actual was summed up, and the method wasapplied in the roadway bolt (cable) supporting design of N1203working face in NingtiaotaCoal Mine. Conduct experimental study in the field of test section, stability monitoring resultsshow bolt (cable) supporting effect was good, achieved remarkable economic and socialbenefits. |
PDF Full Text Request