Effects Of Bolts On The Mechanical Properties Of And Stress Distribution In The Surrounding Rock

The functions of roadway bolts on surrounding rock mainly include two aspects, namely, the influence of bolts on rocks’ mechanical parameters and mechanical status. Various conditions of surrounding rock correspond to different supporting parameters and they both affect the anchorage support effect. In this condition, studying the influence of bolt component and anchorage parameter on mechanical parameter and status has a considerable theoretical significance.This thesis takes the inclined shaft for methane as a studying subject and tests the geological conditions of roadway and analyzes the physical-mechanical property. The seam 2.5m above the roadway is kern stone which is the main zone supported by roof bolt. Prior to studying the effect of inter-row space, prestress and diameter of bolts on E, μ, c, φ and shear strength of anchorage grouted body, we take 2.4m×2.4m×2.4m anchored body above the entry. In the scheme of design, The Largest effect of different inter-row spaced and prestress on Poisson’s ratio has reached around 0.03 ~ 0.04, bolt diameter on the influence of poisson’s ratio is only about 0.01; Meanwhile, diameter and prestress of bolts have effects on elastic modulus, they increase the elastic modulus about 0.2 MPa. different inter-row space, prestress and diameter of bolts have increased cohesion about 0.065~0.15 MPa in the scheme of design. Under the same circumstances the sample angle of internal friction increased 2~3°. In general, The research finds out the decrease of bolt interval and the increase of prestress and bolt diameter will improve the value of E, c, φ and reduce the value of μ. Meanwhile, they will also enhance the shear strength of anchorage grouted body. Then, on the foundation of studying the mechanical parameters of surrounding rocks, we build numerical simulation model to study the prestress distribution principle with the interval of 0.6m, 0.8m, 1.0m, 1.2m or with the bolt length of 1.2m, 1.8m, 2.4m and 3.0m or with the anchorage style of end anchoring-grouting, full-size grouted and extensible bolting or with the prestress of 10 kN, 30 kN, 80 kN, 100 kN or with the anchorage angle of 0, 15, 30, 45, 60. The research finds out different inter-row space, length, prestress, anchorage style and anchorage angle of bolts will have various effects on stress distribution of surrounding rock. Studying the change of mechanical parameters and status is beneficial to the study on bolts’ functional mechanism. The engineering application turns out the enhancement of prestress can control the entry deformation effectively which coincide with the aforementioned research.