Research On The Shear Properties Of Bolted Rock Joints And The Mechanical Model Of Anchoring Rock Mass

At present, the prestressed anchorage technology has become one of the most common technologies in geotechnical engineering. Since the1930s, with decades of large-scale geotechnical engineering construction and related technology development at home and abroad, the prestressed anchorage technology has been widely used in high slope reinforcement, and some important developments in structure design, construction technology and monitoring and reinforcement mechanism study are obtained. But due to the complexity and diversity of rock mass itself, and the mechanical properties closely related with its formation background, history, environment and engineering design, the anchorage mechanism and analysis method is not studied fully, and engineering design and evaluation method is not fully developed, which have become an important bottleneck restricting the development of the technology.On the basis of summarizing the research achievements of others, combining with theoretical analysis, physical model tests and numerical analysis, shear mechanical properties and comprehensive mechanics model of anchoring joint rock mass are studied in this thesis. It has important significance for anchoring technology development and engineering application, etc, but also provides important technical support for the current national foundation construction engineering of the relevant technology.Combined with previous research, this paper conducted a study of the following aspects:(1) The shear mechanical properties of anchoring structure plane. Summarized systematically the research achievements of shear strength criterion of the rock mass structure plane, the contribution of deformation of prestressed bolt to structure plane’shear strength has been studied. And the calculation method of the equivalaent shear strength has been proposed. At same time, on the basis of the calculation method of the equivalent shear strength parameters, the effects that the bolt yield strength, bolt elastic modulus, rock block (cement mortar) compressive strength, dilative angle to bolted structural plane has been analysis.(2) Bolted rock mass structural plane model test. Based on the analysis of the shear mechanical properties of bolted structural plane, the shear mechanical behavior of straight plane and fluctuation plane has been analyses through the model test. According to the results of test, the failure mode under shear condition has been obtained. And the calculation method of bolted joint’s equivalent shear strength has been verified through the different model test of anchoring type. Combined the model test and numerical simulation, this paper discussed the effect of the angle of anchoring, material properties of bolt and joints to the mechanical characteristics of bolted rock mass joint.(3) Bolting structural plane shear failure process numerical simulation. Based on the structural plane physical model test, using the dynamic explicit method, the microscopic mechanical behavior of structural plane has been researched in detail, including the stress distribution, equivalent plastic strain distribution, normal displacement, shear strength characteristics et ac. Combined the results of physical model test, the reinforcement mechanism of prestressed bolt in structural plane is summarized;(4) combined with prestressed bolt reinforcement Mechanism, based on the composite micromechanics Eshelby theory, anchored jointed rock mass as a one-dimensional reinforced composite materials, the comprehensive mechanical model of anchored prestressed rock mass in elastic stage has proposed, and the calculation method of parameters in model has been obtained. According to the theory of fracture mechanics, the cracking question under the axial tension condition has been discussed.(5) The applieation and analysis.Based on the results.of the research, taking the block stability analysis of high slope on the left bank of Jinping hydropower station as an example, the analysis method of the equivalent shear strength of the structural plane has been proposed and verification, the engineering application result is more reasonable compared with the calculation only considers the force in the prestressed anchor cable.