Study And Numerical Analysis Of The Mechanical Properties Of Rock Bolt Support System Composite Material

Rock bolt is often used to reinforce rock mass in many fields of Geotechnical engineering such as tunnel, roadbed, slope and so on. Since the spraying anchor has been used in the construction of the underground project, not only the idea about rock supporting had a radical change from the passively supported to initiatively supported but also the rock bolting system were widely used. In general, the intensity of integrate rock is much higher than the rock mass because the joint and structure faces lessen the intensity of rock. The function of the bolt is to colligate the disjoined rock and enhance the integrity of the rock mass, which is important to enhance the capability of the rock mass to resist the outside force. For these years the geotechnical engineer has accumulated a set of methods to construct the rock bolt. And the rock bolt support has been an effective reinforcing means in the geotechnical engineering field.The current theory about rock bolt system is far behind from the engineering practice, which makes the practice has some blind direction. To change this status a micromechanical composite model is built to evaluate the mechanical properties of the rock bolt support system. The relationship of mechanical properties of the rock bolt composite material and that of the rock mass and bolt is presented in the model.On the basis of the current rock bolt theories and numerical analysis methods a micro-mechanical composite model about the rock bolt system is founded. When calculate the basis elastic constant of anisotropic rock mass bolt system a transfer of the section of the bolt from a round to a rectangle. In the numerical analysis, a program is designed on the basis of the large finite element method software ANSYS to simulate the load condition of the inside laboratory. An ani-axis compressed and three-axis compressed load are simulated. So an equivalent stress-strain curve is drawn from the simulation test and the equivalent elastic moduli of the composite is obtained, so do the cohesion and friction angle.A conclusion can be drawn that the rock bolt enhance the mechanical properties of the rock mass.To considerate the interaction of the rockbolts a larger dimension model is built to simulation the multiple bolt condition. It's concluded that the mechanical properties of the composite is higher than that of single bolt.The diameter of the rockbolt also has an effect on the mechanical properties. The larger is the diameter, the larger of the increase of the module of the rock mass.