Study Of Non-Dig Oscillate-Drilling DTH Orientation Device Applied On Hard Rock Stratum

Non-Dig technology is a kind of underground piping technology which need not digging an open area of earth. It is popularly used in the piping detection, checkup, repair, laying and replacement.Normally, Non-dig orientation drilling projects are mainly applied on soil stratum. The orientation device adopts a non-symmetrical structure with an incline plate. When drill rotates and impacts at the same time, the drilling trace will be a straight line; when drill impacts only without rotation, the drilling trace will follow the direction of incline plate on the orientation device. In another word, the drilling direction will be decided by the orientation device.However, the rock stratum situation is different from soil stratum situation, this non-symmetrical incline plate device can not guide the drilling direction if only impact without rotation. The drill head must rotate to accomplish drilling action. Especially, if the drill stem impacts and rotates at the same time, the drilling process will be more efficient.Currently, the orientation device is the key part and bottleneck of hard rock stratum non-dig technology. It limits the non-dig technology application fields and efficiency. Now, the rock stratum non-dig technology becomes one very important standard to judge the development level of a country in the non-dig drill field. This dissertation is mainly focus on the study of orientation device which applied in hard rock stratum.Nowadays, the technologies that used in the hard rock stratum include: (1) Non-lubricating method (pneumatic DTH): the high-compressed air is used as the driving force of DTH. The advantages of DTH are low pollution, high rock breaking efficiency. The disadvantages are requirement of high air compress devices, special device to remove dust and orientation difficulties. (2) Double drill stems method: the advantages are no requirement of air compressor and mud lubricating devices, good orientation. The disadvantages are complicated double drill stems device structure and low drilling efficiency. (3) Drill hole mud motor method. Advantage is it can be used on existing drill machine without much modification. The disadvantages are short motor life, high waste mud process cost and big orientation diameter.According to the practice, the DTH is the best choice in the rock stratum situation. The key point of DTH is how to resolve the orientation problem. Because the hardness of rock stratum, the drill trace of rock stratum will be a curve shape and the hard drill stem will be damaged easily if it rotates in the hard curve hole. That means the life of drill stem will be shortened. In some serious situations, accidents may happen because of this. If DTH only impact but no rotate, the off-balance bit of DTH will make DTH to be stuck in rock. A novel orientation device need to be worked out to make DTH drill straightly, efficiently, and has long life without drill head stuck.Based on the characteristics and practice of hard rock stratum drill process and DTH working principle, consulting the latest DTH research in the world, Following contributes are accomplished in this dissertation:1. According to the advantages and disadvantages analysis and comparison of popular Non-dig hard rock stratum orientation devices in the world, find out that DTH is the best choice in the hard rock stratum situation because of its high rock breaking efficiency. In the dissertation, the non-dig DTH orientation principle and drill principle are analyzed, and point out the different characteristics of DTH head and piston between horizontal and vertical drilling states; also, analyze the drill stem working principle in the drill hole, and point out the damage mode of drill stem: if rotate and impact at same time, the drill stem is damaged mainly because of endurance failure; impact only without rotation, the drill stem damage mainly come from crooking failure. The best way of DTH drilling should be impacting with addition of slow rotation.2. Based on the analysis of DTH orientation device working principle in the world, and researching DTH patents, according to the special characteristics of hard rock stratum, in this dissertation, we first bring forward a novel Oscillate-Drilling DTH Orientation Device which locates between DTH and drill stem. We give out the working principle of this orientation device and analysis its working process. Also we give out the detail process analysis of input/output ports, blade driving, input/output ports control and single action parts. Among them, input/output ports, their open/close control system, spring selection, chamber sealing and reduction of impaction of blades designs are the key parts of orientation device. The torque and palstance parameters calculation formulas are obtained through theory analysis of oscillating orientation device.3. Three dimensions structure drawing of DTH oscillating orientation device is drafted using 3-D UG NX software. This CAD drawing can be used to find out design failures and correct them before prototype is made.4. Mechanical analysis and oscillation mode simulation of the DTH orientation device is processed using Finite Element Analysis software---ANSYS, especially, the key parts such as central axis and output short axis. This analysis will make sure that these parts'working strength and working life. After DTH orientation device structure design finish, mechanical dynamic analysis software ADAMS is used to do device emulation. Emulation experimental results show: when spring is compressed, spring displacement linearly changes according to strain force. If there is a certain angle between spring pole and port capping block, the capping block will rapidly slide to the other end, and block the opposite port. Then, spring strain will drop to the initial value, and spring will bounce back to its original situation. The simulation makes sure that the structure is reasonable and reliable, then, makes sure the whole design is accurate.5. According to our DTH oscillation orientation device, an unbalanced drill head need to be worked out to match it. In order to fit different stratums requirement, two unbalanced drill head are designed after consulting the best designs in the world. Also in the dissertation, we give out the design requirement and parameter setting requirement of these drill heads. 6.Based on the theoretical analysis and simulation of structure, the oscillating-drilling orientation device prototype is produced and experiments are applied on it. Experimental results of this prototype show: oscillating orientation device not only can accomplish oscillating function, but also the oscillating strength and frequency can be controlled by the pressure and volume of compressed air. Another characteristic of this device is the oscillating angle will always keep the same. The device has the following advantages: simple structure, oscillating smooth and parameter adjustable. It proves the theory analysis and could perform the actions that it supposes to do.As a summary, in this dissertation, following contributes are accomplished:1. A novel oscillating-drilling DTH orientation device design is brought forward which can apply in hard rock stratum. There is no similar structure in the world. This device has the characteristics of simple structure, compact size and low cost, etc.2. Under the same air pressure situation, DTH oscillating orientation device could increase torque output and transfer by changing the size of blade. This makes the device is flexible in different working situations.3. Spring is used as the controller of DTH oscillation orientation device. Spring could rapidly accomplish ports exchange action. Also, spring structure makes the device to be simple, low cost and easy to replace.4. DTH oscillating orientation device applied on DTH will not affect DTH's structure and application requirement. That means this device has good commonality. In the construction site, this device could be directly attached to the existing DTH and do not need complicated assembly or disassembly. Then it will reduce the construction investment cost.5. According to DTH oscillating orientation device, two corresponding unbalanced drill heads are brought forward. This is another novel design that we do not find in the world.All in all, in this dissertation, a DTH oscillating orientation device is brought forward and designed. This simple, easy to use and economic device could be used in hard rock stratum drill situation. It gives out a novel solution for the hard rock non-dig research field.