Mechanical Characteristics And Numerical Simulation Of Full Grouting Bolt

Bolt is one important reinforcement, but the complicated project makes it difficult to learn bolt mechanism, design theory and computation. The keys of learning bolt reinforcement include ensuring the rule of mechanics transfer, setting the stress model of contact surface, adopting the reasonable numerical computation method. Based on the tests and theory, the study of mechanical characteristics of bolt, model of bolted surface will be made.Based on the mechanical state of single full grouted bolt under pull load and the stress curve of bolted contact surface, the stress theory model of homogeneous rock and the reinforcement theory model of jointed rock will be set with simple numerical equation. According to the question in numerical computation, the 3D bolt finite element program will be realized through Fortran and be applied in numerical computation after validation. The conclusion can be drawn that, there is no decoupling and the axial stress is equal to the pull load, and the following axial stress distribution is minus exponent. With the increase of full load, there appears coupling and the all axial stress distribution is minus exponent. At last, the length of decoupling from numerical computation is accordant to the result of examination.After deducing and validating two destroy models, with the 3D finite element method, the trying of using new numerical model will be made to simulate full grouted bolt and the interaction between bolt and grout and get some conclusion. For example, the incline of bolt installation can decrease the shear displacement, weaken the rise of stress, and enhance the shear resistance of jointed rock. Moreover, under the complex action of pull load and bend load, the bolted system will destroy when the compress resistance of rock is poor.Reasonable contact mechanics model between grout and rock can simulate the interaction well and make it clear that the course from load to destroy include elastic distortion phase, slippage distortion phase and decoupling phase. The distribution of stress in every phase is according to the theory result. Even if the length of bolt is different, the axial and shear stress will distort in forepart of bolt, called "critical length".Based on the displacement of excavation, the shear stress model of bolt contact will be set and validated.At last, background on hydroelectric power station, all above theory will be applied in practice project to study the change of rock stability and bolt mechanics. The results provide reference for project.