The full hydraulic tunnel prospecting drill is grinding into holes by rotating and pressing the rock wall of the diamond bit. Usually hard rock with softer hardness of the diamond bit, soft rock to use a bit with greater hardness of the matrix. After so many years of drilling experience, these basic people are probably already familiar.

But experienced teachers will also encounter new problems. For example: "According to experience, the rock is not too hard, the power head rotation speed is normal, the feed pressure is normal, no matter how to increase the feed pressure, the rotary pressure value is not rising, tried a lot of manufacturers of drill bits, but also adjusted the hardness of the drill body, is not footage." In response to such a problem, what do you think?

Some people will think that this full hydraulic tunnel drill strength is not enough, no explosive power; Some people think that the pressure is not completely released, it is the problem of the operating station; Some people think that it is the problem of feeding the oil cylinder and so on. Here are some ideas to share with you:

First, the size of the force that the drill presses on the rock has a range, not the greater the pressure, the better.

Rock breaking mechanism of diamond drill bit: The rock breaking action of diamond drill bit is completed by diamond particles.

In the hard formation, the single diamond makes the rock in a very high stress state under the action of bit weight, which makes the rock undergo lithological transformation from brittle to plastic. Single diamond into the formation, under the action of torque cutting rock, cutting depth is basically equal to the depth of diamond particles.

In some brittle rocks (such as sandstone, limestone, etc.), the diamond particles on the drill bit under the same action of weight on bit torque, the volume of broken rock is much larger than the intake and rotation volume of diamond particles. When the pressure is not large, it can only form a small groove along the direction of the diamond movement, and increasing the pressure will break the rock deep and on both sides of the small groove, so that it exceeds the section size of the diamond particles.

The rock breaking effect of diamond bit is related not only to the weight on bit but also to the lithology and the external factors affecting the lithology (such as pressure, temperature, formation fluid properties, etc.).

There are three kinds of rock breaking: surface crushing, fatigue crushing and volume crushing. Only when the diamond particles have enough specific pressure into the formation rock, so that the rock volume crushing can achieve the ideal rock breaking effect.

Second, when the no-load test machine, the rotary pressure and feed pressure are normal, the feed pressure is normal when drilling, and the machine speed is normal, which can basically eliminate the failure of the rig.

Pressure and speed are the only technical indicators that reflect the shape of the drilling rig when troubleshooting. Don't trust feelings, trust data. The lifting force of the cylinder is only related to the acting cylinder diameter and pressure. The motor torque is only related to its own displacement and pressure; The speed is related to the motor's own displacement, the oil pump displacement and the load size.

Third, according to the physical and mechanical properties of the rock, including the drillability, hardness, strength, grinding line and integrity of the rock, while considering the economic benefits and the actual situation of the construction team, select the drill bit, including the grade, particle size and edge of the diamond, arrangement, strength and concentration, the nature, type and water mouth of the drill head.

After the pressure test investigation, if the technical indicators of the tunnel drill can reach the design indicators, then if you want to solve the problem of penetration, you must work hard from the choice of drill bits. Provide clear pictures of the core cross section and core appearance, clear pictures of the drill bit used, information such as the drill bit's penetration status and life, drilling orientation and the feed pressure value used, according to these data to select the suitable diamond bit. The use of the optional bit needs to be fed back again, the purpose is to first solve the problem of whether the footage can be fed, and then solve the problem of footage efficiency and bit service life. It is usually necessary to choose the 2 to 3 power to achieve the ideal state of footage speed and service life. If the choice of drill bit is not based on the data, just use different manufacturers of drill bits or only use a manufacturer of different body hardness of drill bits, so unscientific selection may be tried many times, the ratio of success is a coincidence, the ratio is not successful is also reasonable.

If you encounter relatively difficult rock formation, basically a diamond drill bit manufacturer by doing 1 to 2 times ratio, if still can not solve the footage problem, replace the next manufacturer, or according to the procedure, if it is to solve the footage problem, then according to the feedback data to find the balance between footage efficiency and time life.