Ensuring the stability of the shaft structure is one of the key technologies for the application of raise boring method. In the process of reaming through rock formations with water disintegration characteristics, the impact of water gushing and drenching may induce partial collapse. To solve this problem, an intelligent temporary while-boring support technology is proposed in this paper. Firstly, the main characteristics of the technology are introduced. Utilizing the space inside the raise boring pipes, the material conveying pipes and nozzle can reach the lower part of the reamer to realize spraying support. Secondly, a composite cementitious supporting material with good mechanical properties is developed to ensure the sealing and waterproofing of the surrounding rock. Thirdly, a test study was carried out on key process parameters. The results show that the best engineering economic benefits under the condition that the rotation speed is 2r/min and the distance between the nozzle and the surrounding rock is 1m. Fourthly, an image classification algorithm based on Resnet-34 convolutional neural network is proposed, which realizes the intelligent judgment of the effect of surrounding rock support. Finally, an industrial test was carried out in Lijiahao Coal Mine. The test results show that the intelligent temporary while-boring support technology proposed in this paper has a good performance, effectively achieving the sealing and water resistance of the surrounding rock, and the shaft structure has not been damaged.
Raise boring method is one of the key technologies for coal mine shaft construction. The typical engineering of raise boring method is two types: large diameter shafts and small diameter gas pipeline shafts. Ensuring the stability of these two types of shaft structures is a key issue that determines the quality of raise boring engineering. In order to solve this problem, a method of evaluating the stability of shaft structure constructed by raise boring method is proposed in this paper. First, for large-diameter shafts, it is clear that the stability of surrounding rock is the key factor. Based on the strength reduction method, the stability coefficient of surrounding rock k0=2.5 is proposed. Secondly, for the small diameter gas pipe shaft, it is clear that the stability of the gas pipe under the pressure of the filling material is the key factor. The functional equations of allowable compressive stress of the pipe material, the initial deviation of the gas pipes and the ultimate pressure are established, and a method with results biased towards safety is proposed for the design and verification of gas pipes.
The drilling method of counter-well drilling rig has become an important construction method for the construction of large inclination Angle pressure pipeline in pumped storage power station. In order to study the effect of the drilling rate on the stability of the surrounding rock of the inclined well. The method of numerical analysis is used to simulate the drilling rate of backwell drilling machine by changing the drilling depth of certain calculation step, and the drilling depth is along the inclined shaft line. The selection of drilling parameters is optimized and the drilling rate of the reverse well rig is determined. The results show that the tunneling rate has a significant influence on the deformation rate of surrounding rock and the change rate of stress gradient in the process of drilling with reverse-well drill. With the increase of drilling rate, the deformation rate and the change rate of stress gradient increase. The variation amplitude of the surrounding rock deformation and stress value at the monitoring point increases first and then decreases, and finally tends to be stable. Under this formation condition and drilling scheme, the deformation of surrounding rocks in wellbore after drilling at the same depth is small, and the effect of stress disturbance is not significant. The maximum deformation of surrounding rocks in inclined Wells is only 0.27mm, and the strong disturbance zone is about 2.0m. Combined with field drilling test results, the optimal drilling rate of reverse well reaming is determined to be 1.2m/h.
Based on the characteristics of raise boring technology and air drilling technology, the construction equipment and process of raise boring with air as circulating medium are studied. Raise air drilling equipment includes the hydraulic control system, the air-cooled cooler and the air compressor. The drilling process is that the bit is cooled by the high-pressure air, at the same time, the broken rock debris generated in the drilling process are discharged to the ground, and the high temperature hydraulic oil is cooled by the air-cooler cooler. By the study above, the problems are solved effectively such as heat dissipation, cooling and rock debris collection and discharge in the process of construction with raise boring machines without drilling fluids. Based on the basic assumption and the aerodynamic theory, the circulation system pressure of the raise air drilling is studied, the calculation method and formula of the annular pressure drop, bit pressure drop and rod pressure drop are presented. The research results can provide theoretical guidance and technical support for the application of raise air drilling technology.
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