Study On The Key Drilling Technology Of Large-diameter By Raise Boring Machine

A lot of the shafts need to build in underground works like electric power station, transportation tunnel, and mine construction as import and export, ventilation, safety escape passage, Most of which have a lower outlet. In the past forward construction as drill and blast method used in such projects, there were many problems in terms of safety and efficiency, the favorable conditions have not fully utilized in the most projects. Therefore, a new raise boring drilling process was proposed in this paper, to achieve comprehensive mechanization for breaking rock and drilling, staff no longer engaged in underground work, and fundamentally solve the drilling security issues.Raise boring technology was the construction technology composed by the pilot hole drilling down, then up by reaming, previously used as a blasting brush several times, as an raise boring method, the required diameter was completing by once reaming, rock breaking area increased12.7times, if drilling diameter increased from1.4m to5m, establishment of the massive rock mechanically breaking theory, a large area exposed wall stabilizing and controlling theory, and Appropriate large-diameter raise boring machine were needed. Based on the applicable conditions and engineering and geological parameters for raise boring method, key technologies of raise boring are determined in this paper via analyzing research background, objective and technical route.The disk cutter or tipped hob cutter were used in mechanical rock cutter tools usually. In this paper, theoretical analysis and test is used to the rock breaking mechanism of the two kinds of cutter. Then LS-DYNA was used to analyze rock breaking process by the insert disk cutter. The experimental object is the granite and the two kind of cutter. Then the fact was found that intrusive depth is proportional to the pressure. Under the same pressure, the indentation depth of the insert disk cutter is relatively large, and the energy consumption in volume of rock crushing unit is relatively small. In order to achieve the same effect, the required pressure of the disc cutter is big. It was not only increases the tangential thrust, but also requires greater torque and drilling rig power. Therefore, this paper argues that raise boring machine was more suitable for the insert disk cutter. This paper analysis the large diameter raise boring reamer, and put forward the moment balance layout principles for the cutter, then in accordance with the principle we designed the reamer with diameter of5m. Base on the analysis result, the main technical parameters was determined for the large diameter raise boring machine: The pilot hole’s diameter is350-380mm; The diameter of the reaming hole is3.5-5.0m; The tensile force of the machine is600kN; The torque is300kNm; The rotation rate is0-5rpm. These parameters determine the design of the large diameter raise boring machine.Because of prolonged exposure during reaming, demolition equipment and support, technical key of raise boring was dependent on stability of shaft wall in raise boring, the main factor affecting stability of shaft wall is Strata condition, ground stress and geological structure during reaming and supporting, the mechanical model of shaft wall was established by means of shear failure strength theory to determine failure condition of shaft wall. The modification of formations was proposed through grouting reinforcement for the soft strata to improve the integrity and equivalent modulus of weak strata, cause the plastic deformation region disappear, and the risk of necking and collapse of weak stratigraphic hole greatly reduce. By calculating contrast, grouting diffusion diameter was about10m in the coal mine rock formation conditions, to achieve shaft wall to stabilize.Based on researching on different strata condition, by which five raise boring technologies were determined, including once completing large diameter raise boring, pre-supporting for local excavation, Directional drilling pilot holes; local unstable ground reinforcement, local broken stratigraphic reinforcement by single-hole grouting, and modifying strata by pre-grouting method on surface, to apply raise boring method in various engineering conditions and geological conditions.Inverted "T" type frame structure for diameter raise boring, drill pipe demolition in the drilling process, force and deformation in drilling rigs were simulated in this paper, a5.0m large-diameter raise boring machine was successfully developed through analyzing the splitting large diameter reaming drill bits and layout of hubs.On this basis, industrial test was carried out in the mine shaft, hob breaking rocks theory and strata stability theory tested by engineering practice, design of large-diameter raise boring machine and raise boring process was reasonable, raise boring method was proven a reliable drilling process.