Method for tunneling through rocks.

Application filed December 26,1906. Serial No, 293,432.

To all whom it may concern;

Be it known that I, Patrick Ford, a citizen of'the United States, and a resident of the city of Chicago, county of Cook, and 5 State of Illinois, have invented certain new and useful Improvements in Methods for Tunneling Through Rocks; and I do hereby declare that the following is a full, clear, and exact description of the same, reference beio ing had to the accompanying drawings, and to the letters of reference marked thereon, which form a part of this specification.

Heretofore in tunneling through rock the operators have constructed a heading in the 15 top of the tunnel, and then blasted out and removed the material in successive benches, thus working from the top downwardly. The material must thus all be lifted against gravity, and both in blasting and in removing 20 the “muck” the work is necessarily slow and' dangerous, inasmuch as the operators are forced to work in a confined space, usually with insufficient ventilation. Furthermore, in tunnels constructed in this manner it has , 25 been impossible to operate the crews to the best advantage, as the muckers or those working to remove the material loosened by the previous blasts cannot work during blasting and cannot resume work yntil the breast pr 30 heading has been cleared of smoke and gas.

In this way one crew is always in the* way of another, and the best that can be accomplished is either to work the crews alternately in shifts or to work the drillers and 35 powder-men at night and thq muckers or those removing material by day, and as crews of both kinds cannot be worked simultaneously and night and day the construction is slow and necessarily expensive. 40 The object of my improved method is to enable rock tunnels to be constructed very rapidly and i cheaply and in such a manner that tne work of one crew can never interfere with that of another, thus enabling the 45 drilling and blasting and the removal of the debris or muck to continue night and day without interruption.

It is a further object of my invention to so , construct the tunnel as to utilize, the force of 50. gravity as far as possible in economizing the labor in all respects and the explosives employed and to afford ultimately a natural draft, whereby the tunnel is at all times rendered clear from smoke and gas, enabling 55 the operations of drilling, blasting, and removing the muck to continue without cessa tion, so far as interference of the work of one crew with, that of another is concerned.

It is also an object of my invention to provide an improved method for blasting out 60 and constructing an under heading at the bottom of the tunnel, whereby the maximum efficiency of each shot is secured.

The invention consists in the matters hereinafter described, and more fully pointed out 55 and defined in the appended claims.

In the drawings, Figure 1 is a longitudinal central section illustrating the construction of a tunnel by my improved method. Fig. 2 is a similar view of the opposite end of the 70 tunnel. Fig. 3 is a transverse section of the tunnel under construction and illustrates a convenient arrangement of the drill-holes to secure maximum efficiency at each shot Fig. 4 is an enlarged longitudinal section 75 thereof, showing the forward inclination of the drill-holes in the roof. Fig. 5 is a front elevation or fragmentary Section, showing in front elevation the arrangement of the drillholes in blasting out the under heading. 80 Fig. 6 is a section taken on line 6 6 of Fig. 5. Fig. 7 is a section taken on line 7 7 of Fig. 5.

As shown in said drawings, A indicates the rock to be excavated at the heading, and B the material to be cast down from the roof 85 after the heading is completed. In the construction of the tunnel an under heading is first constructed with its bottom or floor slightly below the grade of the tunnel and usually for the entire length and width of the 90 tunnel and for a height sufficient to enable the worknlen to work to an advantage to’ complete the tunnel. Usually the height of the under heading is about dine feet, though this of course may vary. 95

In constructing the heading the rock is drilled to the desired depth, as follows: Usually three holes (dependent on the nature of the rock) and indicated by 0 C' C² C³ C⁴. C⁵are drilled on each side of the center and, as iuo shdwn, approximately one-half the distance between the center and the rib or side of the tunnel and one above the other. The holes C to C⁵, inclusive, as shown in dotted lines, all converge inwardly and incline down- 105 wardly at their inner ends or, in other words, are wet holes, and the lowermost holes C C⁵at the inner ends somewhat, below the grade of the tunnel. Between the drill-holes thus formed are drilled other holes approximately no half the distance between the same and the rib or wall of the tunnel, and'these also con840,307 verge inwardly, though at a much less angle | than the holes before described, as shown in Fig. 6, and said holes (indicated by D to D³, inclusive) are arranged staggering with the 5 holes C to C³, inclusive. Eight holes, four on each side, are next drilled along the x'ibs or । sides of the tunnel, (indicated by E to E⁷.) All of these holes, as shown, extend inwardly parallel with and approximately at the rib-line of i o the tunnel, and, as shown, the three lower holes on each side of the tunnel are wet holes or inclined downwardly, as shown in Fig. 7 and in dotted lines in Fig. 5, the lowermost dipping below the grade-line, while the upper holes— 15 namely, E³ E⁴—are dry holes and incline upwardly at their inner ends approximately to or above the roof-line of the heading.

At the top of the heading and, as shown; arranged staggering with the holes at the 20 ribs and those intermediate the rib and the center are four dry roof-holes F to F³, which incline upwardly above the roof-line of the heading.

Of course the number of holes required in 25 each set of holes may vary somewhat with the nature of the rock, as will also the blasting charge.

In blasting the shots are first fired simultaneously in the central holes C to C³, inclu30 sive, thus drawing forward and outwardly the wedge-shaped mass included between said holes, which of course is completely shattered by the discharge. The holes D to D³, inclusive, are next shot, then the rib-holes E 35 to E⁷, inclusive, after which the roof is shot down. Inasmuch as the holes E and E⁷, C and C⁵ incline downwardly below the gradeline, the heading is always constructed with its bottom slightly below grade, and owing to' 40 the converging and downward arrangement of the central intermediate and fib holes the outward downward force of the powder acts to break the rock into small pieces.

After constructing the heading for the en45 tire length of the tunnel or to an air-shaft and slightly below the grade the work of removing the material above the heading, which constitutes the major portion of the material to be handled, is commenced, pref50 erably, at both ends of the tunnel, and for this purpose, referring to Figs. 1 to 4, inclusive, the drill-columns X are arranged on the floor of the heading to provide drill-holes which incline forwardly at the top or toward 55 the completed portion of the tunnel at an angle usually about twenty-two and one-half degrees and which, as shown, are arranged relatively of each other, as indicated in Fig. 3—namely, a line of drill-holes G and G' are όο provided on each side of the center and approximately at their lower end half the distance between the center of the ribs or walls and converge upwardly until the inner ends thereof are close together and slightly above 65 the roof-line. These holes are placed longi tudinally of the tunnel, a distance apart depending upon the nature of the material to be operated upon and the condition and nature of the rock. Between said central holes and the ribs arc provided intermediate holes 7c II H', which also converge toward the center, but at a much less angle of inclination than the central holes G and G' and also incline forwardly at their inner ends and extend slightly above the line of the top of the tun- 75 nel when completed. Along each rib of the tunnel are provided also forwardly-inclined drill-holes 1 I⁷ and extended usually about one foot above the roof of the tunnel when completed. All of said holes are arranged a 8c distance apart longitudinally of the tunnel, dependent on the nature of the rock, usually about nine feet in lime-rock or. sandstone.

In blasting the first two holes G G' are first simultaneously shot, and owing to the inclina- 85 tion of said holes the laiye central mass is thrown down from the roof. The intermediate holes II and ΙΓ are next shot, simultaneously breaking away the intermediate portions of the roof to the top of the tunnel, and 90 this is followed by the shots hr the holes I and I', which break the material out above the roof-line, as shown in Fig. 3. The mass of material thus thrown down at one round of charges is very great, and the muck-heap 95 thus formed extends nearly to the top of the tunnel, and being shattered by the explosion and the fall can be rapidly removed by a steam-shovel Y Y', suitably constructed for the purpose. . 100

The operation is as follows: This muckheap, extending to near the roof, affords adequate protection for the shovel-operators and pit-men at all succeeding blasts and enables the shovel to be continuously operated at the 105 muck-heap independent·of either the drilling or the blasting within the tunnel, and the · same is true at the opposite end of the tunnel, each muck-heap y y' affording a shield to the operators at ’ the shovel during blasting. 11 e Furthermore, as the heading extends the entire length of the tunnel a natural draft of air is afforded therethrough independent of the forced draft ordinarily provided in such cases, and in consequence the smoke of the r 15 blast curls upwardly over the muck-heap at each end and escapes from the tunneling along the roof and does not reach the shoveloperators at all. Furthermore, as but a very small amount of the explosive is required, 120 gravity doing much of die work ordinarily done by the blast, but little smoke or gas as compared with bench-tunneling is formed. Owing to the heading being opened at each end, the drillers at each end thereof work in- 125 dependently of the conditions at the other end of the tunnel, and the drilling continues independently and well ahead or the blasting. The crew at each end of the tunnel, although at all times able to communicate 130

840,307 freely through the heading, work independently of each other, and the individual crews at each end perform their work continuously without reference to the work of the other 5 crew at the same end of the tunnel. Thus none of the time of the men is wasted, though heretofore at least half of the time of each crew was wasted while the otner crews repaired the work, the muck-men waiting for to the drillers and the drillers waiting for the muck-men, and all waiting for the blast. In consequence, by the described method the work is accomplished much more rapidlv and cheaply than heretofore by the older methods 15 and gravity is utilized to the. fullest extent possible in economizing the explosive. Furthermore , there is much less danger to the operators than by other methods,, as no crew can endanger another , though a given work be 20 accomplished in less time and at a mere fraction of. the expense heretofore deemed necessary for constructions of this nature.

While I have described my method with reference to certain arrangements of drill25 holes, it is to be understood that the number and arrangement of these drill-holes may be varied to suit the conditions present—as, for instance, cracks or fractures in the rock may render some holes unnecessary, and of course 30 at times several lines of holes may be shot simultaneously—as, for instance, the ribholes and the roof-holes in forming the heading. It is, of course, to be understood that the conditions present must determine the 35 number and within reasonble limits arrangement and position and the amount of the charges and the order in which the same should be discharged or shot; but I do not purpose limiting this application for patent 40 otherwise than necessitated by the prior art, as obviously there are many details capable of variation without departing from the principles of my invention.