Method of sinking holes in earth's surface

Abstract

A rocket is placed with its front nozzle directed towards the hole face with the distance between said nozzle and the face being about four diameters of the nozzle exit section. Then the rocket is released, started and the face of the hole is worked by the gas-dynamic jet continuously discharged from the rocket nozzle. The force driving the rocket towards the hole face is somewhat stronger than the reaction force of the gas-dynamic jet and other forces directed contrary to the rocket movement. The broken rock is removed from the hole by the streams of waste gases passing out through the gap between the rocket body and the hole walls. Thus, the hole is sunk by breaking the face with the gas-dynamic jet of the rocket being suspended relative to the hole walls and face.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an improvement in the method of sinking holes in the earth's surface and can be successfully employed in geology, construction, agriculture and other fields in which a high-speed sinking of holes is required.

The method according to the invention will be used with greatest advantage for drilling holes such as mapping, structure, key, reconnaissance and prospecting holes made during geological survey, prospecting and exploration of useful minerals; operational holes for the excavation of useful minerals, prospect holes for studying the physical and mechanical properties of rocks and soils, hydrological holes for determining the quality and discharge of subterranean waters. In addition, the present method can be employed for making water drawdown holes to reduce the head of subterranean waters or the inflow of water during shaft sinking, gully holes for the discharge of water from water-bearing horizons, ventilation holes, holes for the supply of air to fire faces during underground gasification of coal and for conducting fuel gas to the surface. The method can also be used for making special-purpose holes, e.g. for the delivery of materials required in fighting underground fires, for lowering electric cables, water and air conduits into underground workings, for delivering air and food and raising the force in case of shaft failures and for building underground gas and oil stores. In agriculture this method can be employed for obtaining drinking and utility water and for land reclamation, while in construction said method will prove useful for drilling holes for bridge piles, industrial and civil buildings, blast shafts and holes.

Known at the present time are a large number of various methods of sinking holes in the earth's surface with the aid of a rock-breaking element, for example, a bit brought into direct contact with the rock to be broken. This method is realized, depending on the hardness of the encountered rocks and the required sinking speed, by means of drill rigs provided with bits of metal or an extra-hard material, e.g. diamond.

The use of rotary bits limits the maximum speed of rock working; thus, even with the bits characterized by a maximum hardness at 600 rpm, the speed of hole sinking is equal to 40 m/hr. The known methods are capable of increasing the drilling speeds by 2 -3 times as a maximum. This impairs the commercial value of drill rigs.

An increase in the speed of hole sinking, particularly in the case of large-diameter holes, leads inevitably to a corresponding increase in the power of the main and auxiliary equipment which, in turn, increases the weight of this equipment.

Since almost all of the units of a drill rig are of metal, the increase in power increases the metal requirement which raises considerably the cost of drill rigs. It should also be borne in mind that the large size and weight of drill rigs impair considerably their transportability; finally, one of the disadvantages of the known methods resides in a comparatively rapid wear of the rock-breaking tool which is in positive contact with the rock.

Thus, at present the employment of the above-described known method restricts the possibility of a sharp increase in the output of drilling equipment.

I have provided a radically new method of sinking holes in the earth's surface by working the face with a gas-dynamic jet continuously discharged from the nozzle of a rocket suspended relative to the hole walls and face and gradually moving together with the sinking face. This method involved additional bombardment of the face with small explosive charges. The rock was broken with a jet of gas discharged under a pressure of 500 -2500 atm. In the case of vertical down-holes, this method ensures a sinking speed of about 1 m/s which exceeds the hole sinking speeds attainable at the present time by one order approximately.

However, this method can be successfully used only for sinking holes with a depth up to a few hundred meters because in the case of longer holes, the broken rock cannot sometimes be taken out together with the stream of gases. Moreover, bombardment of the face with explosives hinders the engineering realization of the method.

It should also be taken in consideration that the above-described method is not adapted for making up-holes by a rocket moving from the rock towards the earth's surface and for driving horizontal and inclined workings.

Lastly, the rockets with a relatively small weight, i.e. those whose weight is smaller than the rocket thrust are difficult to use at the above-mentioned pressures.

OBJECTS AND SUMMARY OF THE INVENTION

An object of the present invention resides in eliminating the abovementioned disadvantages.

Another object of the present invention is to improve the reliability and efficiency of the method of sinking holes in the earth's surface by means of a gas-dynamic jet.

These and other objects are accomplished by providing a method of sinking holes in the earth's surface by breaking the face with a gas-dynamic jet continuously discharged from the nozzle of a rocket suspended relative to the hole walls and face and gradually moving together with the sinking face wherein, according to the invention, the rocket is held before starting in such a position that the distance before its front nozzle and the surface of the face is not smaller than the distance at which, during the rocket starting, the sum of the reaction force of the gas-dynamic jet and the counter-pressure arising between the nose of the rocket and the hole face is counterbalanced by the forces driving the rocket towards the hole face, with said forces being selected to exceed the sum of the reaction force and the forces of friction against the rocket body of the particles of rock and the stream of exhaust gases flowing between the rocket and the hole walls, the amount of gas in the gas-dynamic jet being selected so that the velocity of the exhaust gases exceeds the velocity at which the particle of broken rock of a maximum preset size and mass is in the state of weightlessness.

It has been proved in practice that it is sufficient if the distance from the front nozzle to the hole face is more than four diameters of the nozzle exit section.

For the best conditions of gas and rock discharge, the gap between the rocket body and the hole walls should be about half the maximum diameter of the rocket.

If the weight of the rocket and its fuel is small relative to the reaction force of the jet directed onto the face, it is practicable than an additional gas-dynamic jet be formed and discharged in a direction contrary to the movement of the rocket so as to increase the force which drives the rocket against the hole face.

If the weight of the rocket and its fuel is large relative to the reaction force of the jet acting on the hole face, it is practicable that an additional gas-dynamic jet be formed, moving in the direction of the rocket movement in order to create an additional force assisting in holding the rocket above the hole face.

For making workings directed from the center of the earth towards its surface, it is necessary to provide a gas-dynamic jet directed contrary to the movement of the rocket and creating a force compensating for the weight of the rocket.

Now the invention will be described by way of example with reference to the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of the rocket for sinking holes in the earth's surface;

FIG. 2 shows a device for determining the distance from the nozzle exit section to the hole face;

FIG. 3 shows the position of the rocket in the hole during operation;

FIG. 4 shows the position of the rocket as it starts driving a horizontal hole; and

FIG. 5 is a section of the rocket shown in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

Theoretically, the method according to the invention can be realized with any solid-propellant rocket known at the present time. However, the best results will be obtained by using a special rocket shown diagrammatically in FIG. 1.

The rocket A comprises a body 2 provided with a combustion chamber 3 wich accommodates fuel cells 4 referred to hereinafter in a number of cases as "fuel" for the sake of brevity. The rocket has a working element 5 provided with a nozzle 6. The nozzle 6 is a face-breaking element because it is the gas-dynamic jet discharged from this nozzle which breaks the face of the hole.

Before starting, the rocket should be positioned at a certain distance from a face surface 7, for example as shown in FIG. 1, and held by grips 8. The nozzle 6 should be set at such a distance from the face surface 7 that the sum of the forces acting on the face during rocket starting would be equal to zero. Theoretically, the value of 1 can be found on the basis of the following considerations. At the moment of starting, the working element 5 of the rocket A is acted upon by the force of the weight (P.sub.1) of the rocket, by the force of weight (P.sub.2) of its fuel, the reaction force (P.sub.3) of the gas-dynamic jet discharged from the nozzle of the rocket and by the force (P.sub.4) of the counterpressure arising between the nose of the rocket and the hole face. Thus, it is necessary to satisfy the following condition:

P.sub.1 + P.sub.2 - P.sub.3 - P.sub.4 = 0 (1)

in the above equation, the force of the counterpressure depends on the distance 1 while the other variables depend on the class of the rocket. It should be understood that rockets of a certain class have the same thrust and weight.

Hence, for satisfying equation (1), the distance 1 should be selected so that the nozzle 6 would be at such a distance from the face surface at which, during rocket starting, the sum of the reaction force of the gas-dynamic jet and the force of counter-pressure arising between the nose of the rocket and the hole face would be counterbalanced by the forces driving the rocket towards the surface of the hole face, in this case by the forces P.sub.1 and P.sub.2. Theoretical calculations of 1 are possible, though being extremely difficult.

However, in each specific instance, the value of 1 for the rockets of the given class can be found experimentally by means of a device illustrated in FIG. 2. This device comprises a solid unbreakable base 9 made, for example, of steel; said base mounts a vertical metal pipe 10 simulating the hole in the earth and for which purpose the end of said pipe has a cylindrical portion and a tapered portion.

The rocket is provided with a rigidly fastened bar 11 while the pipe 10 has a rack 12. The rocket is placed at a certain distance from the base 9 and started. As soon as the rocket engine attains the rated working conditions, (i.e. the conditions under which it burns the rated amount of fuel per second), the rocket becomes stabilized in a certain position. Now the position of the bar 11 with relation to the rack 12 makes it possible to find the distance from the rocket nozzle 6 to the base 9. While using other rockets of the same class, this distance can be taken for a reference value, i.e. for a distance at which the nozzle of the rocket A should be set from the face surface. Experiments have shown that this distance should be equal to at least four diameters of the exit section of the rocket face-breaking nozzle.

Thus, if the above requirement is satisfied, then immediately after starting, the rocket will be in a suspended state relative to the hole face. The gas-dynamic jet discharged from the nozzle 6 and acting on the face will break the rock and form a hole. Let us consider the process of forming the hole. While sinking a down-hole, the rocket moves towards the face as shown in FIG. 3 under the effect of forces driving the rocket towards the hole face; at the same time, the reaction force of the gas-dynamic jet tends to push the rocket out of the hole. Hence, it is necessary that the forces driving the rocket A towards the face surface should be at least equal to or, for the best effect, somewhat larger than, the reaction force of the gas- dynamic jet. The force driving the rocket towards the hole face consists of the sum of weights (P.sub.1 + P.sub.2) of the rocket and its fuel which must exceed the rocket thrust. Even in such cases when the weight of the rocket and fuel is considerably larger than its thrust, the counterpressure grows so largely with the reduction of the distance between the nose of the rocket 1 and the hole face, that physical contact between the rocket nozzle and the face is rendered practically impossible. It should be noted that when the forces driving the rocket towards the hole face are equal to the reaction force of the gas-dynamic jet, the rocket will move towards the center of the earth because breaking of the rock in the face increases the distance between the rocket nozzle and the face which, in turn, reduces the force of counterpressure in which case the rocket will tend to occupy a position in which the equation (1) is satisfied.

The movement of the rocket in the hole creates an additional force tending to push the rocket out of the hole. This force is created by friction against the rocket body of the rock particles and the stream of waste gases of the gas-dynamic jet.

Therefore, the forces which drive the rocket towards the face, in this case the weight of the rocket and its fuel, should be selected so that their sum would exceed the sum of the reaction force and the forces of friction against the rocket body of the ascending stream containing the particles of rock and the waste gases discharged through the gap between the rocket body and the hole walls.

To ensure normal functioning of the rocket in the hole, a gap must be provided between the rocket and the hole walls, and a certain velocity of the ascending stream.

It has been established that the most stable operation of the rocket in the hole is ensured when the gap between the rocket body and the hole wall is 0.3 the rocket diameter and over.

The preliminary calculations of the amount of gas in the gas-dynamic jet ensuring the required velocity of the ascending stream can be based on the nature of the ground and the maximum size of the particles formed during face working. It has been found experimentally that an efficient clearing of the face and rapid removal of the rock particles or stones up to 50 mm in cross-section can be ensured when the ascending stream moves at a speed of 80 -100 m/s. If one takes in account that the temperature of the gas discharged from the nozzle is about 1000.degree.C and that the speed of hole sinking (about 1 m/s) ensures intensive heat exchange between the gas and the particles of soil, the volume of gas diminishes sharply under these conditions which should be borne in mind while calculating the velocity of the ascending stream. Each particular design of the rocket characterized by the chemical composition of its fuel, working pressure in its combustion chamber, the critical section of its nozzle and a number of other factors has the high and low limits of gas discharge per second.

Given the cross-sectional area of the hole, the amount of gas discharged per second and an approximate percentage of solids in the stream of waste gases, one can derive the required speed (V.sub.1) of the ascending stream from the following formula: ##EQU1## where

Q.sub.1 = volume of gas, m.sup.3 /s, at a mean stable temperature of the stream;

Q.sub.2 = volumetric content of rock per cubic meter of gas;

F = cross-sectional area of the hole, m.sup..

The volume of gas can be calculated by the formula: ##EQU2## where

Q.sub.0 = amount of gas generated per second at t = 0.degree.C;

t = temperature of gas in the hole mouth, degrees Centigrade.

The lift force of the stream (A) can be found from the formula:

A = .rho.V.sub.1.sup.2 (4)

where .rho. = density of the ascending stream of gases.

The density (.rho.) of the stream of gases can be determined as follows: ##EQU3## where G = weight of gas.

To determine the speed of removal of the broken rock particles, it is necessary to find the excess speed which is the difference between the actual velocity of the stream and the critical velocity for the particles of a certain weight, size (d) and shape. In this case, the criticial velocity is the velocity at which the particles of rock withdrawn with the stream of gases become weightless.

The critical velocity of the rock particles can be derived from the following formula: ##EQU4## where

V.sub.2 = velocity of gas stream at which the rock particle becomes weightless;

C = correction factor for the shape of particles;

d = maximum diameter of the particle (m)

.gamma..sub.1 = volumetric weight of discharged rock, kg/m.sup.3 ;

.gamma..sub.2 = volumetric weight of gas, kg/m.sup.3.

For example, for round particles of 50 mm diameter C = 3.5. When the volumetric weight of the discharged rock is 2400 kg/m.sup.3 and that of gas if 0.5 kg/m.sup.3, the critical velocity of particles is 54.5 m/s.

The actual speed (V.sub.3) of the calculated particle in the hole is:

V.sub.3 = V.sub.1 - V.sub.2 (7)

thus, the total velocity of the gas stream can be calculated with a certain degree of approximation by the formula: ##EQU5##

When the amount of gas is 15 m.sup.3 at 0.degree.C and the temperature of gas stream is 300.degree.C, the value of Q is 30.9 m.sup.3. The value of V.sub.1 = 80 m/s.

Hence, the actual speed of rock particles of a maximum size discharged from the hole is:

v.sub.3 = V.sub.1 - V.sub.2 = 80 - 54.5 = 25.5 m/s.

As shown by experiments, the method according to the invention at this velocity of the gas stream ensures a complete clearing of the hole from the broken rock at the rate of about 1 ton per sec.

It has been stated above that the rocket is driven towards the face surface in the down holes by the forces pressing the rocket towards the face; in the case of the rocket shown in FIG. 1, these forces are constituted by the weight of the rocket and its fuel. In the present case, it is necessary that the sum of weights of the rocket and its fuel should be larger than the sum of the reaction force of the gas-dynamic jet acting on the face and the forces of friction against the rocket body of the rock particles and the stream of waste gases discharged through the gap between the rocket body and the hole walls.

Thus, in the process of hole sinking, the rocket A is acted upon by the forces satisfying the following requirement:

P.sub.1 + P.sub.2 - P.sub.3 - P.sub.4 - P.sub.5 = 0 (9)

where

P.sub.1 = weight of the rocket;

P.sub.2 = weight of the fuel;

P.sub.3 = reaction force of the gas-dynamic jet;

P.sub.4 = force of the counterpressure arising between the nose portion of the rocket and the hole face;

P.sub.5 = force of friction against the rocket body of the rock particles and stream of waste gases.

If this requirement is satisfied, the rocket is suspended relative to the face and the hole walls so that the face is worked by the gas-dynamic jet discharged from the face-breaking nozzle.

As soon as the hole has been sunk to the preset depth, the rocket is withdrawn by increasing its thrust to such a limit when P.sub.3 becomes larger than the sum of P.sub.1 + P.sub.2 which pushes the rocket from the hole. It is also possible to use a rocket with a ballast weight which can be removed after sinking the hole so that P.sub.1 + P.sub.2 becomes smaller than P.sub.3. In this case, the rocket will also start backing out of the hole.

If the weight of the rocket and its fuel is considerably smaller than the thrust of the rocket engine, it is necessary to provide an additional force driving the rocket towards the face, i.e. to ensure conditions under which the forces driving the rocket towards the face are stronger than the sum of the reaction force of the gas-dynamic jet and the force of friction against the rocket body of the rock particles and the stream of waste gases discharged through the gap between the rocket body and the hole walls. For this purppose, the rocket shown in FIG. 3 will be effective. This rocket consists of a body 2a with a combustion chamber 3a accommodating fuel cells 4a. The rocket has a working element provided with a nozzle 6a which discharges a gas-dynamic jet acting on the face along the axis of rocket movement, and a row of nozzles 13. The working element of the rocket also has several nozzles 6b which discharge gas-dynamic jets acting on the face of the hole at a certain angle to the direction of rocket movement which increases the diameter of the hole.

The gas-dynamic jet discharged from the nozzles 13 is directed against the movement of the rocket thus creating a reaction force (.SIGMA.P.sub.13) which drives the rocket towards the face and adds to the weight of the rocket proper. Besides, these nozzles increase additionally the hole diameter, thus improving the conditions of its sinking.

Thus, when a hole is sunk by means of a rocket whose own weight is smaller than its thrust, the following condition must be satisfied: P.sub.1 + P.sub.2 + .SIGMA.P.sub.13.sup.. cos .alpha. - P.sub.3 - P.sub.4 = 0 (10)

where .SIGMA.P.sub.13 = reaction force created by the discharge of gases through nozzles 13;

.alpha.= angle at which gases are discharged from the nozzles 13 relative to the fore-and-aft axis of the rocket.

While raising an up-hole, the face-breaking nozzle of the rocket should be set at the same distance from the face as that used in sinking a down-hole. However, the thrust in this case should be directed towards the hole face. This thrust should be larger than the weight of the rocket and its fuel plus the forces of friction against the rocket body of the waste gases and rock particles in the gap between the rocket body and the hole walls.

Thus, when the rocket is used for raising an up-hole, the following condition must be satisfied:

.SIGMA.P.sub.13 < .SIGMA.P (P.sub.1 + P.sub.2 + P.sub.3 + P.sub.5) (11)

the method according to the invention can also be employed for driving horizontal working. FIGS. 4 and 5 show the rocket in a starting position before driving a horizontal working.

This rocket consists of a body 2c, a working element 5c provided with a face-breaking nozzle 6c and a group of nozzles 13c. Besides, the body 2c is fitted with fins 14 which stabilize the rocket in a horizontal position. The rocket is held horizontally by the lift force created by the stream of gases acting on the fins. The rocket is started from a pipe 15. At the beginning of the hole sinking, the rocket is set at the same distance 1 as in any other method of working. This method is efficient for making short holes. In this case, the relation of forces while the rocket is in the hole should be as follows:

.SIGMA.P.sub.13 cos .alpha. > .SIGMA. (P.sub.3 + P.sub.5) (12)

here the weight of the rocket and its fuel is compensated for mainly by the aerodynamic lift force.

The use of the method according to the invention increases the hole sinking speed dozens of times as compared with the existing methods, and at the same time ensures a high quality of the hole walls.

Moreover, the employment of the method according to the invention reduces the weight of the drilling equipment also by dozens of times.

Claims

I claim:

1. A method of sinking holes in the earth's surface by working the hole face with a gas-dynamic jet continuously discharged from the nozzle of a rocket suspended relative to the hole walls and face and gradually moving together with the sinking face characterized by holding a rocket before starting in such a position that the distance between its front nozzle and the surface of the hole face is not smaller than the distance at which, during rocket starting, the sum of a reaction force of the gas-dynamic jet and a counter-pressure arrising between the nose of the rocket and the hole face is counter balanced by forces driving the rocket towards the hole face, selecting said forces to exceed the sum of the reaction force and forces of friction against the rocket body of the particles of rock and the stram waste gases flowing between the rocket and the hole walls, and selecting the amount of gas in the gas-dynamic jet so that the velocity of the waste gases would exceed the velocity at which the particle of broken rock of a maximum pre-set size and mass is in the state of weightlessness, wherein the gap between the rocket body and the hole walls is about half the maximum rocket diameter.

2. The method according to claim 1 wherein, in case of a small weight of the rocket and its fuel relative to the reaction force of the jet pushing the rocket out of the hole, an additional gas-dynamic jet is formed and dischared in a direction contrary to the movement of the rocket, increasing the force which drives the rocket towards the hole face, and enlarging the diameter of the hole.

3. The method according to claim 1 wherein, in case of a large weight of the rocket and its fuel relative to the reaction jet acting on the face, an additional gas-dynamic jet is formed and discharged in the direction of rocket movement thus creating an additional force which assists in holding the rocket above the hole face and increases the efficiency of face working.

4. The method according to claim 1 wherein, for raising up-holes, a gas-dynamic jet is created and discharged in a direction contrary to rocket movement to provide a force compensating for the weight of the rocket.

5. The method according to claim 1 wherein, a gas-dynamic jet is formed and discharged along the rocket movement at a certain angle thereto.