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BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The present invention relates to the field of trenchless tunneling by jacking or ramming pipe casing of large diameter over long distances, especially with respect to the installation of 100-400 feet of pipe casing which is larger than 72 inches in diameter. 
     2. Description of Related Art 
     There are various methods currently used to install underground pipe without digging trenches, commonly referred to as trenchless tunneling. These methods use pipe ramming and jacking, tunnel boring machines, or Micro-Tunneling. 
     Trenchless tunneling methods use tunnel boring machines (TBM) that include a boring shield that either pushes itself forward with completed extruded segments either made from precast concrete or bolted steel panels. Variation on the boring method has the TBM or mole mounted on or in front of the first casing pipe that is thereafter pushed into the formed tunnel with large hydraulic jacks. As these tunnel boring machines move forward through the ground, the soil is removed and typically mixed with a fluid and the mixture pumped out of the tunnel into a separation plant, wherein the solids are separated from the fluids. These methods do not work well in shallow applications, depending on soil type. A minimum industry standard requirement is a cover over the tunnel to be installed of at least two times the machine diameter. Tunnel boring is very slow and very expensive because of the type of equipment required. 
     TBM or Micro-tunneling involves underground trenchless tunneling in which energy is used to excavate the soil loose during the tunneling operation for soil removal. Again, Micro-tunneling is very slow in terms of the time required to create a tunnel and can be quite expensive 
     Trenchless tunneling methods that use pipe ramming or pipe jacking are known. The method typically uses a casing liner that is pushed underground into the tunnel by either a pneumatic ramming hammer, a set of hydraulic rams in tandem, or a combination of the two. The tunnel is typically started in a jacking pit that is dug to a depth to which a casing pipe or tunnel liner will be placed under the ground. 
     Capacities of currently employed ramming hammers and jacking pipe casing installations to date have been limited in capacity, such as total length or pipe size, requiring internal excavation as sections of pipe are installed in the tunnel. The ramming hammers and jacking rams have not had sufficient force for extended long tunnels with large diameters such as 6 ft. through 12 ft. for extended long tunnels above 100 feet because of the immense friction encountered as the pipe casing sections are formed and the entire casing gets longer and longer. By excavating concurrently with ramming or jacking, the risks of a tunnel cave-in or settlement of the face is a possible danger. The production process or the time required for installing the tunnel using jacking or ramming or a combination thereof is impacted by an interruption of having to excavate the pipe interior before another pipe section can be driven. 
     U.S. Pat. No. 5,632,575 issued May 27, 1997, describes a method and apparatus for controlled piping of bentonite around a pipe-jacked tunnel. Although this patent shows trenchless tunneling, it may use a combination of a tunnel boring machine or even tunnel excavation using hand labor. The system uses a tunnel ram and requires lubrication that presses the limit of the hydraulic jacking. This is a completely different operation than pile driving a tunnel casing great lengths using a horizontal pile driver. 
     U.S. Pat. No. 4,391,553 issued Jul. 5, 1983, shows a hydraulic control system and method of controlling the operation of tunneling apparatus. This shows the conventional use of a pair of hydraulic rams and pumps. This system is severely limited in total pipe casing achievable distances and operates completely differently than Applicant&#39;s invention. 
     U.S. Pat. No. 4,557,672 issued Dec. 10, 1985, shows an apparatus and method for tunnel construction with shield drive. Again, this is a trenchless tunneling method that is completely different than Applicant&#39;s invention. This method uses a shield drive and incorporates a concrete tunnel lining directly behind the shield. This is very slow and expensive. 
     U.S. Pat. No. 3,742,718 issued Jul. 3, 1973, shows a tube driving apparatus for driving large diameter tubes where a limited amount of space is available. The method and apparatus shown are severely limited in the total trenchless pipe distances available of the tube construction, which is completely different than that disclosed by Applicant&#39;s invention. 
     U.S. Pat. No. 4,398,845 issued Aug. 16, 1983, shows a tunnel driving apparatus that incorporates a cutter shield with a plurality of drive members in a side-by-side, cylindrical array. This system is completely different than that employed by Applicant. 
     The subject of the present invention overcomes the problems discussed above by providing a method and system that uses a powerful pile driving hammer, like those used for offshore vertical pile driving construction, that greatly increases the length of a trenchless tunnel casing to be driven while greatly reducing the risk of cave-in. With existing jacking/ramming systems, as more tunnel liner sections are installed, the friction between the liner sections and interior and exterior surface and the surrounding soil increases. Due to the limited driving capacity of these systems, this phenomenon requires the interior plug to be removed as each tunnel section is added in order to reduce the upper pushing limit of the typically used jacking equipment. 
     There is a need for a method and apparatus that has sufficient driving force to drive large sections of tunnel casing, or even the entire tunnel casing, before excavation of the soil plug begins in order to improve safety and production and also allow greater diameter pipe and longer drive lengths in one continuous operation without excavation, thereby reducing the risk of collapse of the face or settlement of the ground. This is important since typically, these installations underground are often planned under busy roadways or railroads (or a combination of both), whereby it is not practical or cost effective or even possible to open cut with open trenches. Thus trenchless tunneling is extremely important in certain environments. With the present invention, the Applicant can use trenchless tunneling to drive underground pipe casing over 72 inches in diameter and up to 168 inches for distances exceeding 100 feet. This can also be done very quickly in a matter of hours instead of days and weeks compared to other methods of trenchless tunneling at greatly reduced cost. 
     The use of an impact piling (pile driving) hammer (such as a modified Hydrohammer manufactured by IHC) that uses low frequency and high velocity and high energy is preferred over the use of a low energy, low velocity, and high frequency system, such as ramming, in that the soil particles are forcibly sheared with the former and not simply brought in suspension as with the latter. The limitations of pipe ramming/jacking are especially evident for installation done in damp or fluid-bearing soils where the pneumatic ramming can lead to soil liquification that can cause the soil plug to run. 
     Another advantage of the large capacity available with the low frequency and high velocity and high energy system in accordance with the present invention using a piling hammer is that on particularly environmentally sensitive projects, a hammer of sufficient driving capacity can be chosen so as to eliminate the need to lubricate. Thus, in certain environmental situations, the system avoids environmental contamination when the installation, for example, is near or over fish-bearing creeks. However, if lubrication is permitted, it also allows for even more increased distance that can be obtained using the pile driving hammer in accordance with the present invention. 
     SUMMARY OF INVENTION 
     A trenchless tunneling system and method for driving horizontally placed large pipe casings that are joined sequentially together in sections to form a tunnel which is safer and more efficient over current methods. The present invention can provide for the creation of a tunnel using casings of large diameter (over 72 inches) for great lengths (exceeding 100 feet) without digging a trench. 
     One objective of the invention is to provide a method and system or installation of pipe casings in areas where open cut excavation is not possible or practical, such as under heavily traveled roads, highways, railroads, or any combination thereof. 
     Another advantage of the large capacity availability with the low frequency and high velocity and high energy system is that on particularly environmentally sensitive projects a hammer of sufficient capacity may be chosen in accordance with the present invention to eliminate the need to lubricate with bentonite or other additives, avoiding environmental contamination. 
     Another object of the invention is to provide a hammer of sufficient capacity that on less environmentally sensitive projects, especially where tunnel distances are required exceeding 300 feet trenchless, the invention can provide a method and apparatus for providing lubricant, such as bentonite, on the inside or outside or both, for great distances. 
     And yet another object of the invention is to provide a method that temporarily stabilizes soil at the entry phase of the casing pipe to be installed whenever the entry of the installation is near the shoulder of a road, a railroad embankment, or other structure requiring settlement avoidance. 
     It is very important that a temporary means of soil support is provided at the leading open end of the pipe as soon as the drive is started to avoid collapse of the soil into the pipe, resulting in loss ground and surface settlement. A temporary seal made up of interlocking steel plates against the cutting shoe form an enclosure at the front end, thus a temporary bulkhead, whilst at a variable distance, dependent upon the soil type to be tunneled, a temporary bulkhead is placed inside the casing to be driven in such a way that the space between the two bulkheads can then be filled with a flowable fill. The rear bulkhead is constructed out of aluminum, and is a shield that uses an inflatable rubber seal of which the friction between the interface with the internal diameter of the casing pipe may be controlled by means of regulating the pressure in the inflatable seal; this bulkhead together with the flowable fill plug forms a controllable resistance that will support the face upon entry, thereby avoiding surface settlement. 
    
    
     In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings. 
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a side elevational schematic diagram of the invention. 
     FIG. 1A is a top plan schematic of the pile driving hammer used in the invention. 
     FIG. 2A is a top plan view of the invention. 
     FIG. 2B is a side elevational view of the invention. 
     FIG. 3 is a side elevational view partially in cross section of the helmet used in the invention. 
     FIG. 4 is a top plan view of the cutting/lube shoe of the present invention. 
     FIG. 5 is a side view in elevation, partially in cross section and cut away, of the cutting/lube shoe. 
     FIG. 6 is a diagram showing the distribution of lubrication around the outside and inside of the pipe casing during installation driving. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, and in particular, FIG. 1, a schematic diagram of the invention is shown. 
     The invention is used to install a large steel pipe casing of up to 168 inches diameter, up to two inches thickness, a distance of at least 250 feet underground without digging a trench to install the pipe. Once the pipe casing has been installed, soil is removed, and the desired final pipe is placed in the casing. This could be a large concrete water or sewerage pipe placed inside the permanent pipe casing. All this is accomplished without digging a trench. 
     The overall installation involves digging a ground entrance pit and placing a pile driving hammer of significant driving force and a support system horizontally in the pit forming an entrance to the underground tunnel to be driven. The installation requires that the pipe casing be formed by a series of pipe casing segments, each about 30 feet (or smaller) in length, that are sequentially joined (end-to-end) as each pipe casing segment is driven until the desired total length of the pipe casing is achieved underground without a trench. As each section of pipe casing is driven into the earth, a new section is added either by welding or by a coupling device. 
     A large pile driving hammer  12  is placed in a pit generally horizontally in front of the location where the pipe  18  is to be installed. A pit may be required, although, depending upon the job, a pit may not be necessary. The hammer is placed on a stability framework fixed to the ground to ensure that the hammer head strikes generally evenly. The pile driving hammer is similar to a vertical pile driving hammer modified for horizontal use to compensate for the loss of the “g” force of gravity used by vertical hammers. 
     As shown in FIG. 1, the driving end of the hammer  12  head strikes a helmet  14  abutting plate  16 . The plate  16  is mounted against helmet  14 . This helmet, also referred to as the primary helmet, preferably strikes a secondary helmet, which, in its turn, may strike a series of helmets that may be used depending upon the diameter of casing pipe to be driven. The final helmet, when there is a series of helmets, then strikes a drive plate, which in turn strikes the first section of casing pipe  18  to be driven. The lead casing  18  has a cutting head  20  described below. Depending on the soil and application, the cutting head may be steerable. Subsequently when the first casing pipe has been driven, the driving apparatus, including the drive helmets, is withdrawn from the first casing pipe. Next the second casing pipe to be driven is inserted between the final driving helmet and plate and the first casing pipe installed. The connection between the first and second casing pipe may be formed through the use of a proprietary locking joint, or through welding. After the connection between the first and second casing pipe is made, the driving apparatus and helmets with push ring are placed against the driven end of the second casing pipe whereafter the above described driving process is repeated. This sequence will repeat itself until the last casing pipe is driven. Each casing may be up to thirty feet in length. 
     It is preferred that the hammer head is approximately 24-36 inches in diameter, and the plate is approximately 64 inches in diameter, and preferably made of a rigid material. The hollow helmet or helmets, and the pipe to be inserted, are preferred to be up to approximately 120 inches in diameter and may be 160 or up to 190 inches in diameter. 
     The hammer  12  is preferably a high energy impact hammer (generally 60,000-260,000 foot/pounds) such as one used in large offshore vertical piling construction projects. In use, the hammer hits approximately 40-60 blows per minute, and can drive 30 feet of large diameter pipe on average in about 35 minutes. However, unlike offshore construction, the hammer is used horizontally rather than vertically. Several elements must be in place to ensure that the hammer operates as intended. Larger hammers may be used as necessary up to 500,000 foot/pounds. 
     FIG. 1A shows a schematic diagram of the high force, horizontal pile driver  12  used to drive the pipe casing  110  and the drive hammer set-up when driving horizontally. To counteract against the increased pressure in the gas buffer, a constant tension loading device (pull down force) is required to keep the hammer housing  112  firmly on the anvil. A spring arrangement  116  is located between tension wires  114  and the hammer  118  to prevent too high shock loads in these wires. The system incorporates a winch that includes a plurality of lines and pulleys and springs attached to pulleys that are permanently mounted to the earth to provide the constant tension through a constant tension loading device (CTLD). The pile driving hammer  118  is not in itself the present invention but is the hammer being used that includes improvements for specifically driving pipe casing horizontally to avoid having to dig trenches. 
     FIGS. 2A and 2B show the present invention which includes the pile driving hammer  12  connected to helmets  14  and pipe casing  18  in the pipe driving position. The hammer is supported on a frame  20 . The system includes a tension cable  24 , a winch  22  and pulleys  26 ,  28  and  32  mounted to rigid pilings  34  and  34   a . An end cap  30   a  and cable tension shock absorbing devices  30  hold the hammer in alignment and in tension. 
     FIG. 3 shows a side view of an improved helmet  40  used with the present invention. The use of the improved helmet  40  reduces the overall length required for the pile driving hammer pit in as much as a good portion of the hammer  12  is mounted inside the helmet  40 . The helmet  40  itself is mounted partially inside the first casing pipe to be driven. The hammer end  12   a  strikes interior mounted anvil  46  constructed of TI high carbon material inside the helmet  40 . The helmet  40  is an elongated cylindrical cast iron unit that has an elongated circular central chamber  40   c  that receives the driver hammer  12  which provides the high impact force to anvil  40  positioned permanently inside the helmet interior chamber  40   c . The helmet flanged end  40   a  is conical in shape and makes direct contact with a plate connected directly to the pipe casing section being driven and provides the force transferred from the hammer  12  through the helmet  40  against the entire perimeter edge of the pipe casing being driven. The end of the helmet includes a conical flange portion with an extended circular area that extends beyond the cylindrical outer body of the hammer. The hammer is aligned by a plurality of spacers  41  positioned between the outer hammer  12  body surface and the inside chamber  40   c  against anvil  46 . The flanged conical end  40   a  of helmet is shaped so as to be able to engage pipe casings of different diameters through, including additional flanged ends  42  and  44  to extend the helmet diameter for larger pipe. Therefore the helmet  40  includes an adjustable sized diameter for different diameter pipes for different jobs without having to create a separate helmet for each different size pipe casing. The helmet itself is made of high-strength cast-iron and sized in length to save approximately 15-20 feet of excavation in the initial hammer installation pit by allowing a significant portion of the hammer to be received inside the helmet and impacting the anvil inside the helmet  40 , all while the helmet is partially received inside the first casing pipe. 
     Referring to FIG. 2A and 2B, the hammer  12  is placed on a ground supporting framework  20 . On the back of the hammer  12 , a tension bracket  30   a  incorporating pulleys with shock absorbers are attached. In the preferred embodiment, two pulleys  26  and  28  are firmly attached either directly or indirectly into the ground to pilings  34  generally behind the entry seal. Two other pulleys  31  are firmly fixed in a position generally located near the bracket  30   a  fixed to the body of the hammer. Depending upon the needs of the project, other pulley and dampening systems may be used. The shock absorbers help dampen the rebound of the hammer as it is used, helps provide a constant tension on the hammer, and helps, stabilize the invention. The pulley system attachment to the piling  34   a  has a load cell in the dead end of the system so as to be able to maintain a constant tension through out the pulley system. It is preferred that the load cell has a programmable logic controller (PLC) controlling the hydraulic winch  22 . The pulley system preferably provides a one to five mechanical advantage. 
     The impetus for the hammer  12  is preferably provided by a hydraulic cylinder which is actuated by compression of a nitrogen cylinder. However, other force drivers for providing impetus are known in the art. 
     When the installation of the pipe casing begins, the first thirty foot section of pipe casing is permanently attached at the leading end to a cutting head  20  shown in FIGS. 4,  5 , and  7 . The cutting head  20  is a tubular or annular—shaped conduit  50  that has a hardened knife blade shaped leading cutting edge  56  around its perimeter cutting through rock and ground as the pipe casing is driven. The blade edge  56  extends around the entire perimeter of the leading edge of the cutting head. The cutting head  20  back perimeter  58  is welded to the leading edge of the first pipe casing that will be driven to begin the tunnel. The cutting head  20  also includes a lubricant dispensing shoe which is used in conjunction with the cutting edge to dispense a lubricant such as Bentonite to reduce the friction between the pipe casing cutting head  20  and the earth, both inside the pipe casing and outside the pipe casing. A particular circumferential lubricant distribution pattern (inside and outside) for certain jobs that are not environmentally sensitive to the lubricant is selected in order to increase the overall total length of pipe casing that can be driven to reduce earth friction on the pipe casing during the pipe driving operations. 
     There are some operations where the environment is sensitive and cannot use a lubricant because the lubricant should not be dispensed into the soil such as near underground streams. However if lubricant can be used to increase the effective force of the hammer to reduce friction, the result is extending the length of pipe casing that can be driven for any given scenario. In order to supply the lubricant to the cutting head and shoe, there must be two supply pipes, one for supplying the inside of the cutting head and the other to supply the outside of the cutting head with lubricant. As each section of pipe casing is added to the total pipe driven, the lubricant pipes must be welded or attached to the outside of each give casing, with conduit couplings joining the lubricant supply pipes attached between each pipe casing section. 
     As shown in FIG. 5, cutting head body  50  has an annular groove  64  on the outside of the cutting head. Spacers  62  are attached by welding to the cutting head. The spacers  62  are attached to an annular cover ring  60  that forms an annular chamber around cutting head body  50  that can receive lubricant from supply pipe  52 . A second supply pipe  54  is in fluid communication with an interior dispensing channel  70  on the inside wall of cutting head body  50  formed by annular inside groove  70  and annular cover ring  66  attached by spacers  68  to the inside wall of body  50 . It is desirous to reduce friction to keep the lowest physical height profile inside and outside the cutting head possible for the lubricant dispensing channels since the dirt is traveling both inside and outside of the cutting head during the entire operation. 
     Referring now to FIG. 4 the cutting head  50  is shown attached to first and second lubrication supply pipes  52  and  54 . The first lubrication conduit  52  is connected through cover plate  60  that can dispense lubricant approximately 120-270 degrees around the outside top perimeter of the cutting head. 
     The second lubricant supply conduit  54  is shown which has an outlet passage  72  through body  50  on the inside of the cutting head which can also distribute the lubricant approximate 90 degrees around the inside bottom wall of the cutting head in a different arc circumferential pattern than the outside pattern lubricant distribution. The annular plate is mounted on the inside of the cutting head as shown in FIG. 4 attached by spacers  68  welded to the inside of the cutting head surface above and over groove or channel  70  completely around the inside the cutting head body  50 . The outlet of the second supply conduit  54  for the lubricant goes through passage  72  and empties into the chamber  70  formed by the inside channel and annular covering  66  for dispensing lubrication on the inside of the cutting head. 
     Referring now to FIG. 5, the cutting head has a Bentonite lubricant receiving and dispensing chamber  64  on the outside with a protective shoe  74  in front of the first supply conduit  52 . Also shown is the connection and outlet from the second supply conduit  54  for supplying lubricant to the inside of the cutting head through the chamber  70  annularly disposed. Note how pointed the blade edge  56  is at the leading end of the cutting head. FIG. 6 shows a circle divided into arc degree segments and the approximate distribution angles for the inside of the pipe and the exterior of the pipe for the dispensing of the Bentonite lubricant. The outside of the pipe has lubricant distributed from 225 degrees to 135 degrees. The inside of the pipe casing has lubricant dispensed from 135 degrees to 225 degrees. Dispensing of the lubricant both on the inside and the outside is dependent upon the number of ports or openings in the outside spacer  62  and the inside spacer  68 . 
     A cutting head  20  is used for cutting through the earth and can include a ground lubrication dispenser shoe. The cutting head  50  is attached to the first lead pipe casing and is used to begin cutting and forming a tunnel. Lubrication if necessary helps break the friction of the soil both inside and outside the cutting head and the pipe casing. The head  50  is tubular in shape, and is blade edged at the annexed rim where initial contact is made with the ground during driving. An outer shoe is angled around outer perimeter of the cutting head. The outer shoe includes dispensing openings. Along the interior perimeter of the cutting head is an inner shoe, angled to reduce friction through the earth for a low physical height profile. The inner shoe dispensing openings extends approximately from the four o&#39;clock position to the eight o&#39;clock position when looking directly at the head. 
     The inner dispensing shoe and the outer dispensing shoe are preferably welded onto the cutting head. The dispensing pressure of the bentonite lubricant is preferably approximately 60 pounds per square inch and the pressure is preferably adjustable. 
     Along the top body of the casing pipe going to the shoes are two conduits for a lubricant, such as bentonite. One conduit is for outside dispensing and the other for inside dispensing. The bentonite or its equivalent is pumped into the shoes and around the head through the two separate circuits. When bentonite is used, it is preferable that the bentonite is of a wallpaper paste consistency. As pipe casing sections are attached behind the cutting head, it is preferred that two supply pipes for the lubricant are attached to each new pipe casing section. The attachment to the pipe casing is preferred to be a saddle for the conduit on the outside and inside of the pipe section. It is also preferred that the conduits are welded in place. The conduits are preferred to be attached to each other in series as pipe casings are added, and attached to the dispensing shoes on the cutting head. 
     Since the cutting head is hollow, a plug of soil is formed. In one embodiment, a plug of soil retention material is placed in the casing pipe behind the cutting head and before the hammer begins operation. Thus, the soil does not easily fall back in repose as it naturally would thereby causing undesirable inflow of soil at the point of entry of the installation trench, thus causing unwanted settlement of the surface. It is also preferred that the plug comprises flowable fill material. In another embodiment, equipment such as tunnel digging machinery as shown in the attached drawings is used to excavate the soil in the tubing. 
     It may be preferable to have a preparation area for the hammer, especially where the conduit is to be installed at least partly underground. In that case, a pit surrounded by steel plates as shown in the attached figures may be placed around the hammer of the invention. 
     The instant invention has been shown and described herein in what is considered to be the most practical and preferred embodiment. It is recognized, however, that departures may be made therefrom within the scope of the invention and that obvious modifications will occur to a person skilled in the art.

Summary:
A method and apparatus for installing a pipe casing underground without a trench for distances up to 400 feet with pipe casing up to 168 inches in diameter. The system uses a modified high energy piling hammer to mobilize the energy to drive the casings or tubings that make up the instant tunnel. An example of a piling hammer used in the present invention is the IHC Hydrohammer line of models in between the S-90 and S-280. Specific models planned to be used in this invention, depending on diameter and length requirements and type of soil in the planned alignment, are the Models S-90, S-150, S-280, S-400 and S-500. The present invention&#39;s Hydrohammers are needed to be held against the casing pipe to be driven with a force equal to the reactional force of the hammer during recharging of the hammer&#39;s system. A special helmet and cutting head increase operational capabilities.