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Technology of How to Perforate a Down The Hole Drill in Complex Geological Conditions
Aug 20, 2018

Technology of How to Perforate a Down The Hole Drill in Complex Geological Conditions


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Deep hole blasting is a commonly used blasting method, which plays an important role in earth and stone blasting. It is widely used in open pit mining projects, mountain industrial site leveling, railway and highway construction. Therefore, the perforation process is the premise of deep hole blasting. The parameters of the hole network are inconsistent with the design, and the quality of the perforation will affect the blasting quality (especially pre-cracking blasting) and may even cause blasting accidents. At the same time, the improvement of the perforation efficiency can also effectively reduce the cost, speed up the progress of the project, and ensure the smooth progress of the following processes.



1. Filling and Hole Making Method


The filling hole can be applied to the piercing operation of step deep hole loose blasting, expansion and stripping engineering. It can strictly follow the design requirements, and the requirements for blasting parameters such as hole position, hole direction and hole network parameters are not affected by geological conditions. The hole formation rate is high, the quality is good, and the footage is fast. It can effectively overcome the surface covering soil and the backfilled gravel loose layer. The difficulty of loosening the loose surface layer by the ultra-deep blasting of the step. Perforation construction on these working platforms, the opening of the downhole drilling operation is quite difficult, it is easy to form the funnel mouth, causing the slag to circulate in the hole, or the perforation is forced to affect the working efficiency, resulting in an increase in the cost of perforation; or after the perforation is made, The upper part of the hole collapses, blocking the hole and forming a waste hole, which brings many difficulties to the next process. A method of filling the slime with an opening or a part to be filled.



Can successfully solve the above problems. The specific method is as follows:


1. According to the design requirements, align the hole position and hole direction; 2 firstly perforate 0.5-1.0 m deep, fill the mud and tamping; zero wind pressure, give back the perforation depth about 0.5 m, low wind pressure, low pressure perforation 2.0 to 2.5 meters, filling the pores, reciprocating circulation, until the slag, sound, barometer, ammeter, etc. are normal; 3 If the mud is too wet or too much, the impactor loses its function, or the wet mud is blocked after the drill is put forward In the case of holes, it is only necessary to fill the holes with appropriate slag or stones; 4 The method of filling holes is generally only suitable for the main pole portion, which is about 9.0 meters;




Make a record for the blasting construction to review the correction.



2 Through Crack Perforation



The geological structure of the blasting mountain has a great influence on the blasting effect and blasting safety, and also affects the downhole drilling operation. The top of the Qingcaoling limestone mine in Xingfeng Group is close to the top of the mine and the part of the ore body in the coal mining area. The integrity of the long-term moving roof rock is seriously damaged, and several new structures have been formed. In the face, the rock mass becomes a discrete body, and the surface is severely slumped and displaced. Therefore, the drilling of the downhole hole in the cracks of many rock layers should pay special attention to the safety of the drilling machine, and it is easy to cause the drilling tool to become stuck. Cracked rock formations can be understood according to the following aspects:



(1) According to geological survey data

(2) On-site surface observation and judgment

(3) Accumulation of perforation experience


When the wind pressure of the rig wind pressure gauge suddenly decreases and there is no slag discharge in the hole, it indicates that the hole has encountered cracks. At this time, the drilling tool can be proposed, using the rope ruler and the small mirror (when the sun is sufficient), the rope ruler and the flashlight to observe the crack position, the width, and the presence or absence of the card stone. If the crack is within 5 cm, the hole can be refilled after filling with the filling method; if the crack is too wide and there is no card stone, it can continue; if there is a stuck stone, it can be repeatedly crushed with a drill or blasted with a small dose of drug pack. Remember not to continue to perforate without disposing of the ka stone; at the same time, make a perforation record for inspection during blasting construction.

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3 Over-Dissolved Hole Perforation


Limestone mines generally have a dissolution phenomenon and there are caves. The existence of karst cave not only affects the charging construction and blasting effect, but also affects the perforation operation, which is prone to squinting or partial holes, sometimes even cards.


Dead diamonds. There are three types of caves:


(1) The entire cave is filled with soil;

(2) The cave part is filled with soil;

(3) The cave is partially filled with mud and partially filled with water.


When the impactor of the submerged hole drilling operation is not loud or the sound is small, the slag is clod or mud, and when the footage is accelerated, it means that the full-filled cave is encountered, and the full wind pressure, low pressure and low footage can be adopted. Perforation, if the soil is too dry, water can be added to form a hole. If the soil is too wet, slag or stone can be added to the hole. When piercing, the hole is filled with water column, the drill sharp impactor does not ring, and when the ruler accelerates the slag as mud, the full-wind pressure can be used to blow off the dissolved water, and each hole is about 1 meter after the mud, and the hole is appropriately oriented. Add slag or stones to form holes. When the perforated drilling tool falls sharply, the impactor does not ring, and then the footage is accelerated, the impactor does not ring or the sound is small, and the "first wind pressure, back pressure" operation can be taken to prevent the eye from slipping or the partial hole, thereby avoiding increasing the rotary resistance of the drill. Increasing the swing current sometimes causes the impactor and the drill pipe to shear and break.



4 Drilling Tool Stuck Processing


During the perforation process, the operator should do “one listen, two check, three look”, that is, listen to the sound of the drill hole to judge the situation inside the hole; second check the equipment fault and check the fault inside the hole; Look at the air pressure gauge, the current meter is normal, and the slag in the hole is normal. However, in special cases, there are still stuck stuck tools. There are three common types:


4.1 Rock Slag Hug Drill

This type of drilling tool is usually caused by a sudden stop of supply of wind or a sharp decrease in wind pressure, a large hole in the borehole, and a small crack. When using wet rock drilling, add more water, use the wind to flush the water from the bottom of the hole to form a certain gap, and slowly rotate the drill to supplement the hammer. When dry rock drilling, first press down to close the impactor, and send the full blowhole to remove the rock powder. Reverse, forward rotation. When the jog drill has room for rotation, continuously hammer the drill pipe and immediately send the wind edge. Lift the drill.




4.2 Stone Seam Sticking Accident

It is caused by the stone seam stuck in the drill bit or the impactor. At this time, do not rotate the drill, lift the drill upward, jog reverse, forward and back. If the seam is large, the wind can be added, and the lubricating oil such as waste engine oil or diesel oil is added to the hole, and the effect is remarkable. Small seams should not stop the wind, otherwise it will form a slag, stone joint comprehensive hug.


4.3 Stone Stuck DTH Hammer

It is caused by the collapse of the hole wall or the stone in the stone. At this time, do not drill, you should drill down, while jogging and forward, jog the drill up and down, crush the stone, and let the gravel fall into the bottom of the hole.


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