Title of Invention

"A METHOD FOR THE CONSTRUCTION OF UNDER WATER TUNNELS"

Abstract

A process for the construction of underwater tunnels comprising, converting pre-constructed old ship hulls of the desired dimensions into tubular sections by cutting off unnecessary and undesirable portions of the ship while retaining the water tight integrity of the suitable portions of their hulls, constructing water tight steel bulkheads inside the said tube sections while the hull is afloat, constructing another vertical bulkhead extending to the ceiling of the tunnel and running along the total length of the tube sections, sandballasting the exposed outer sections, providing end concrete connectors on each end of the said tubular sections by connecting steel serrations thereon, coating each end connector face with a thick coat of conventional sealants before installation, pressure forcing in any conventional manner further sealant in the gaps between the end connectors, lowering the finished tubular section onto concrete provided with concrete stools and located in a pre-dug trench in the sea bed, wherein the steps of sandballasting, providing the end connectors, and coating of the exterior surface of the tubular section are done while the said hull tubular section is afloat.

Full Text

A PROCESS FOR THE CONSTRUCTION OF UNDERSEA TUNNELS The present invention relates to a process for the construction of undersea tunnels. The present invention also relates to a process for providing means of communication and transport by the construction of undersea tunnels using ship hulls. Background of the invention A major problem faced by coastal cities such as Mumbai, Chennai, Calcutta in India is of excessive population and traffic. The large scale migration to these cities has not been accompanied by a corresponding increase in space for residential areas. This has resulted in the establishment of smaller satellite towns in the suburbs or on islands near these cities. The increasing encroachment on public roads, the increase in daily commuter traffic and the accompanying pollution has resulted in a chaotic situation in respect of public services. As the population and hence the traffic of these cities have grown, there has been no progress towards linking the suburbs, particularly, those on island peninsulas with the mainland. Various schemes proposed to solve this problem have not been successful or are not feasible due to the existing presence of port and harbour construction in such cities. For example, in Mumbai, a bridge to link the mainland with the island peninsula has been discounted because of the presence of the Indian naval base, Bombay docks and JNPT Docks located inside the harbour. While there have been proposals to construct tunnels undersea, the costs are exorbitant. Also, the deep undersea underground tunneling technology that India requires is expensive and requires foreign expertise. Another problem which coastal cities in Asia with large harbours face is with respect to disposal of scrap metal from ships that have been de-commissioned and are towed into their ports for dismantling. A very large number of ships, both bulk carriers and very large crude carriers (hereinafter VLCC'S) are being disposed for scrap to the scrap yards of Bangladesh, Pakistan, India and China. These ships with their hulls are relatively in good condition are cut apart and their steel sold as scrap and used as feed stock for the steel mills of India, Bangladesh, or Pakistan. These ships are sturdy and built to very high standards due to the great dynamic and static stresses they face in a seaway, and a majority of these ships hulls are in sound condition when they are scrapped. They are relatively free of corrosion or excessive waste. Their inherent strength can be gauged from the fact that a tanker hull of about of 350 meters length by 54 meters width and 26 meters depth can carry a quarter million tons of weight i.e. crude oil and be pounded by the ocean forces. However, these ships are scrapped primarily due to new stringent environmental laws, obsolete old inefficient oil guzzling machinery, or where they have been victims of fires and collision accidents. A few are also scrapped because of excessive corrosion or requirement of massive amounts of steel renewal which are not cost-effective. Related art There have been several plans and efforts to construct undersea tunnels across the world. The most notable of these has been the construction of the undersea channel between England and France capable of carrying both road and train traffic. The construction of the tunnel involved an effort from both sides of the English Channel using extremely large tunnel-boring machines (TBMs), weighing as much as 1,300 tons and boasting rotary blades up to 28 feet across. The cutter heads of these machines featured replaceable ceramic teeth. Despite this, the only about 15 feet of earth an hour could be excavated. The tunnel boring machine used a laser probe to keep the tunnel bore on line and level. Disposal of the chalky waste that was excavated from the seabed was a major hindrance in the construction of the tunnel. The chalk dirt had to be scooped up in buckets behind the head and dumped into conveyors carrying the waste to small boxcars on rails. Another problem was the necessity to provide reinforcement in the excavated area. An erector system with hydraulic jacks was required to place reinforced concrete segments about 23 inches thick along the walls of the tunnel. The variations in the chalk formation along the tunnel line required different levels of reinforcement along the entire length of excavation. The tunnel project also resulted in soaring costs beyond the original estimate of 3.6 billion, noise, environmental damage to picturesque countryside, fear of terrorist attacks, (a defence system of baited traps, electrified barriers, pits, screens, and patrolmen with dart guns has been provided as well as closed-circuit TV), wildlife getting through, especially animals such as foxes carrying rabies and fear of fire. Despite all these problems, the Channel tunnel has achieved a traffic of about 1,000 vehicles an hour in each direction (may reach up to 4,000 an hour at full capacity), 31 million passengers per year and about 16 million tons of freight per year US Patent 3826098 provides a method and means for reducing wave pressures on undersea constructions by a method and device for reducing lifting forces, on an undersea construction, resting on the bottom of the sea. Such lifting forces are caused by passing wave troughs which create more significant low pressures on the upper side of the construction than those low pressures at the bottom of the sea. The invention effects pressure equalization between said two low-pressure areas. Such pressure equalization can be achieved by placing the area below the bottom of the construction in open communication with the area above the construction. US Patent 3708987 relates to a reservoir of prestressed reinforced concrete preferably for storing hydrocarbons, adapted so that it can be submerged in the sea so that it rests freely on the bottom thereof, said reservoir comprising a series of cylindrical walls into which radiating partitions fit so that they bear on a central pillar formed by two circular slabs fitting into the walls and the partitions. The bottom of the reservoir has a reinforcement designed to receive a supporting pad or cushion, and the top of the reservoir carries at least one columnar support having a working platform at its upper end. This platform remains above the surface of the sea after the reservoir has been submerged. Each support is in the form of a hollow shaft and serves to carry means connecting the tank with safety elements on the work platform. Further, each shaft is provided with first means which allow the tank to be submerged in the sea so that it can rest freely on the bottom thereof and second means which allow the tank to "breath" by enabling the safety elements to be brought into communication with the free atmosphere. Preferably each shaft has a number of cells therein which can be successively flooded with seawater to lower the reservoir to the sea bottom in stages and desirably the reservoir is made from pre-stressed reinforced concrete. US Patent 4189252 relates to an improved structure adapted for undersea construction comprising a plurality of foundation blocks, each foundation block comprising a rectahedral parallelepiped opposite faces of which are concave and convex, respectively, the opposite faces being sized and shaped to inter engage matingly, such foundation blocks being inter fitted into a three-dimensional array; a plurality of base pad units supporting said foundation blocks, each base pad unit comprising a rectahedral parallelepiped one face of which is convex, the opposite face of which has a plurality of protruding lugs, and the intermediate faces of which have T-shaped slots extending the. length of each side, such base pad units being inter fitted into a two-dimensional array by means of I-shaped keys which fit into adjacent T-shaped slots; a plurality of leg blocks supporting said base pad units, each of said leg blocks comprising a rectangular parallelepiped one face of which is convex, the opposite face of which is concave, the opposite faces being sized and shaped to inter engage matingly, and the intermediate faces of which have T-shaped slots in each side, such plurality of leg blocks being inter fitted into a three-dimensional array by means of the mating concave-convex faces in one direction and by means of T-shaped key assemblies which fit into adjacent T-shaped slots in the other two directions, some of said leg blocks inter engaging matingly with some of said foundation blocks by means of inter engaging, mating convex and concave faces. The key assemblies comprise four T-shaped keys symmetrically mounted on a planar base. The heads of said T-shaped keys extend perpendicularly to the plane of said planar base and fit into T-shaped slots in adjacent leg blocks. US Patent 4498268 relates to an improved structure adapted for undersea construction is described comprising a plurality of foundation blocks, each foundation block comprising a rectahedral parallelepiped opposite faces of which are concave and convex, respectively, the opposite faces being sized and shaped to inter engage matingly, such foundation blocks being inter fitted into a three-dimensional array; a plurality of base pad units supporting said foundation blocks, each base pad unit comprising a rectahedral parallelepiped one face of which is convex, the opposite face of which has a plurality of protruding lugs, and the intermediate faces of which have T-shaped slots extending the length of each side, such base pad units being inter fitted into a two-dimensional array by means of I-shaped keys which fit into adjacent T-shaped slots; a plurality of leg blocks supporting said base pad units, each of said leg blocks comprising a rectangular parallelepiped one face of which is convex, the opposite face of which is concave, the opposite faces being sized and shaped to inter engage matingly, and the intermediate faces of which have T-shaped slots in each side, such plurality of leg blocks being inter fitted into a three-dimensional array by means of the mating concave-convex faces in one direction and by means of T-shaped key assemblies which fit into adjacent T-shaped slots in the other two directions, some of said leg blocks inter engaging matingly with some of said foundation blocks by means of inter engaging, mating convex and concave faces. The key assemblies comprise four T-shaped keys symmetrically mounted on a planar base. The heads of said T-shaped keys extend perpendicularly to the plane of said planar base and fit into T-shaped slots in adjacent leg blocks. However, the method and device of this patent is expensive and involves the use of expensive technology. Also, this technology is not very compatible for undersea tunnel construction. US Patent 5042959 relates to an undersea operation system comprising an undersea operation machine for conducting undersea operations such as undersea construction and the collection of stones and rocks, and a backup ship operatively connected to this undersea operation machine. The undersea operation machine includes a vehicle, arms which, are connected to this vehicle, etc. The vehicle and the arms are operated by hydraulic pressure, which is supplied through a cable connecting the undersea operation machine to the backup ship. This ensures a smooth operation of the undersea operation machine even in a deep-sea region. Prior art methods and devices for construction under the seabed have been found to prohibitively expensive or inappropriate for adaptation to undersea tunnel construction. Therefore, there is an urgent need for providing a method of undersea tunnel construction which is capable of bearing the high loads generated under the sea and is also at the same time inexpensive and resource intensive. Objects of the invention It is an object of the invention to provide a method for the construction of undersea tunnels that obviate the above-mentioned drawbacks. It is another object of the invention to provide a process by which, old ship hulls that have been discarded for scrap can be recycled. It is another object of the invention to provide a process for the construction of undersea tunnels utilising discarded ship hulls. It is a further object of the invention to provide a simplified and cost effective process for the construction of undersea passageways. It is a further object of this invention to provide a process for the construction of multi-component underwater tunnels from existing resources at low cost. It is yet another object of the invention to provide a process for the construction of underwater tunnels that is environmentally benign and non-damaging. It is a further object of the invention to provide a process for the construction of underwater tunnels that are capable of easy repair without necessitating halting of all traffic. It is another object of the invention to provide a process for the construction of underwater tunnels that are stable structures. Summary of the invention Accordingly the present invention relates to a process for the construction of underwater tunnels, said process comprising, converting pre-constructed old ship hulls of the desired dimensions into tubular sections by cutting off unnecessary and undesirable portions of the ship in any conventional manner while retaining the watertight integrity of the suitable portions of their hulls, constructing water tight steel bulkheads inside the said tube sections while the hull is afloat, constructing another vertical bulkhead extending to the ceiling of the tunnel and running along the total length of the tube sections, sandblasting the exposed outer sections, providing end concrete connectors on each end of the said tubular sections by connecting steel serrations thereon, coating each end connector face with a thick coat of conventional sealant before installation to ensure that the steel plate serrations mesh with the face of the other end connector of the other hull section, pressure forcing further of said sealant into the gaps between the end connectors, and lowering the finished tubular section onto concrete piling provided with concrete stools and located in a pre-dug trench in the seabed, wherein the steps of sandblasting, providing the end connectors, and coating of the exterior surface of the tubular section are done while the said hull tubular section is afloat. In one embodiment of the invention, the ballasting of the tubular sections is done by using water ballast. In another embodiment of the invention, the ballasting of the invention is done by using sand ballast. In a further embodiment of the invention, the external surface of the tunnel section is coated with a protective coating of gunnite/concrete in order to protect it from corrosion and in order to provide increased stability and strength. In a further embodiment of the invention, the interiors of the tubular sections are provided with utility, ventilation, electrical, drainage and escape conduits continuously and simultaneously while work is being done on the exteriors. In yet another embodiment of the invention, the partitions in the existing compartments of the watertight hull tubular sections are removed after the tubular section is sunk in order to provide a continuous tunnel passageway. In a further embodiment of the invention, the end concrete connectors comprise steel plates welded to the main sections and filled with steel re-enforcing rods and concrete/cement fill. In a still further embodiment of the invention the ends of these serrations slightly protrude out of the ends. In another embodiment of the invention the rubber and bitumen are forced into a compact mass between the opposing steel serration's between the sections to form a water-tight connection allowing little expansion or contraction. In another embodiment of the invention, the conventional sealant used is selected from rubber, bitumen epoxy and the like. Brief description of the accompanying drawings Figure 1 shows the principal particulars and dimensions of a very large crude carrier or tanker that can be used to construct the tunnel of the invention. Figure 2 shows a front elevation and cut away section of a tanker or Very Large Crude Carrier. Figure 3 A shows the side elevation. Figure 3 B shows the top elevation or top profile of this 2,50,000 metric ton dead weight Very Large Crude Carrier (VLCC). Figure 4A is a diagrammatic representation of side tank separation. Figure 4B is a diagrammatic representation of separation and re-floating of side tanks. f Figure 5 is a diagrammatic representation of preparation of tunnel tubes. Figure 5 A shows the stage of surface preparation. Figure 5B shows the stage of construction of watertight steel bulkheads inside these tube sections while afloat. Figure 5 C shows the construction of another vertical bulkhead to act as the road divider extending to the ceiling of the tunnel. Figure 5 D is a diagrammatic representation of the final horizontal position of the tubes. Figure 5 E is a diagrammatic representation of the tube end concrete connectors constructed on each end of the tube sections. Figure 5 F shows one completed tubular section with provision for utilities, pipelines and ventilation that will be joined to several similar tube sections to form the underground/under water tunnel. Figure 6 is a freehand drawing of the trench in which the tubular sections will be located. Figure 7 is a freehand representation of the method by which the tubes are sunk into the trench and joined. Figure 8 is a freehand representation of the final road tunnel showing the final stage and cross section of the tunnel link with the drain, utility, ventilation, service/escape spaces, the road and the divider. Detailed description of the invention This new technique and process of construction of under ground/ sub-sea tunnels for road and rail passage utilises a new, unique and very innovative, simple, cheap and quick method. The existing method of constructing undersea tunnels involves the construction of tubular sections out of steel/concrete in very large dry docks built for this purpose and with the appropriate specifications, digging of a undersea/underground trench, these sections are sunk and thereafter joined together and buried by overfill to form undersea road rail or other type of utility tunnels. The method of construction of the present invention utilises already constructed old hulls of ships meant for scrap and modifying them, converting them into tubular sections of the tunnel thus using their already constructed portions saving enormous costs and time. This results in a tremendous saving in the costs and time as special and expensive dry docks need not be built for this purpose. To construct the tunnel sections, a suitable old ship is identified and selected. The ship is then taken to a scrap yard or a suitable beach where their unwanted sections are excised and the suitable portions of their hulls retained with their water tight integrity intact. These portions are then re-floated. Other such similar usable sections are towed to a place where they are required, then are sunk after dredging of a trench and placed on already constructed base pilling stools depending on the bottom structure to be joined together to form the undersea portions of the sub-sea road/rail or other type of tunnels. These are then permanently buried under sea/under ground with overfill earth material. The method of the present invention provides an innovative and cheap way to construct the undersea section of the tunnels from sections of old ships e.g. ship tankers hulls like Very Large Crude Carriers (VLCC'S) or even suitable size bulk carrier hulls which may be used depending on available right dimensions and the dimensions required for the tunnel specifications. To illustrate the process of construction, a particular size of a proposed sub-sea tunnel constructed out of a a Very Large Crude Carrier or tanker (whose dimensions are shown in figure 1) is described. As shown in figure 3, 3 A and 3 B, a tanker normally has 7 sets of tanks (1, 2, 3, 4, 5, 6, 7) ranged along its longitudinal length. Each set is further sub-divided into three transverse tanks which are the wing tank (port), center tank and wing tank (starboard) (Figure 4 A). The ship hull has a rectangular or parallel body for most of its middle length (that is about 225 meters) except for the forecastle (forward) and accommodation (aft) regions where there is a turn or sheer in its hull. The wing tanks are normally of equal dimensions along the entire length of ship also (i.e. 17 meters width, 26 meters height as in this tanker's case). Therefore, a tubular length of above dimensions and about 225 meters length could be salvaged from this hull in an intact watertight tubular section. So in other words from the hull of one such tanker two rectangular sections of dimensions 17 meters x 26 meters x 225 meters could be salvaged. These hollow sections are utilised to form the underwater tunnel sections for say a tunnel of a length of about 2 kilometres. It is estimated that a total of 5 tanker hulls (VLCC's) will be utilised to form the total length of the undersea section of this tunnel. Such a task is carried out in a scrap yard with a wide variation in tide say for example Alang near Bhavnagar port in the state of Gujarat, India which is about 200 nautical miles from Bombay. Alang has a very large tidal variation (a minimum of 10 meters on spring tides). These tankers are beached on existing plots meant for scrapping and their forward and accommodation after portions are cut away and scrapped. After cutting off the forward and aft portions these tanker hulls are cut in order to separate the two sets of watertight rectangular tube sections (wing or side tank sections) from the main hull (figure 4 B). Each section will still have the five water tight transverse bulkhead sections as originally designed (figure 4 A). There are five main watertight compartments (2A-6 A, 2B-6BO in these sections with two open-ended compartments (1A, 7A, IB, 7B) on each side. These sections are then re-floated and towed to a suitable location near to where they will be installed ultimately. While afloat, construction of watertight steel bulkheads is carried out inside these tube sections (Figure 5B). These will constitute the floor of the road or rail tunnel. The formation fo the tube floor as the floor of the road and/or rail tunnel ensures that an appropirate gap is provided below the floor for lower water ballast space. A road divider is constructed by making another vertical bulkhead (Figure 5C, II) extending to the ceiling of the tunnel and running along the total length of the tube sections. Thus, each of the five compartments is further subdivided. These bulkheads will ultimately become the floor and divider of the road or rail tunnel. Sandblasting of the exposed outer sections is carried out after the construction of the road dividers and the floor of the tunnel section. The tunnel section is then coated with protective coatings and a steel mesh gunnite/concrete coating for corrosion protection. This procedure is done while the hull sections are afloat and near the final location of the tunnel to save expensive dry docking. The use of the above bulkheads aids in the rotation of the structures by selective ballasting by filling them with water. This also helps in the exposure of all surfaces of the newly formed compartments and bringing them to a final horizontal position after completion of the outer surface anti-corrosive protection. The interiors of the tubular sections are provided with utility, ventilation, electrical, drainage and escape conduits continuously and simultaneously while work is being done on the exteriors (Figure 5D, 5F). Additionally, the hulls are coated inside with a protective coat similar to the one outside before carrying out this work. The interior of the tunnel can then contain a plurality of lanes each way with dividers as desired according to the specification of the tunnel requirement. The end concrete connectors are constructed on each end of these sections both sides using steel serration's, i.e. steel plates welded to the main sections and filled with steel re-enforcing rods and concrete/cement fill. The ends of these serrations slightly protrude out of the ends (Figure 5E). The protruding serration ends can act as connectors between different tunnel sections, which may vary in size due to different tanker dimensions available as well as provide a water tight connection without any welding or physical connection. Coating each end connector face with a thick coat of conventional sealants such as rubber/bitumen epoxy, before installation will ensure that the steel plate serrations mesh with the face of the other end connector of the other hull section. Subsequently, further amounts of conventional sealants such as rubber and bitumen are forced into a compact mass between the opposing steel serration's between the sections to form a water tight connection and allowing little expansion or contraction also. The required tubular sections are then ready for installation. The tubular sections are lowered into the pre-dug trench in the seabed and rest upon concrete pilings. The undersea trench is dug by dredging the seabed for laying of the under sea tunnel sections. A trench of about 35 meters depth with a width of 35 meters will be suitable to install these tanker hull tunnel sections. Undersea pilings are done to bedrock inside this trench to install on top of them concrete stools on which the tanker hull sections will rest. A longer base is required for end sections where the tunnel will emerge over sea/ land on both sides. After the tubular sections are lowered onto the pilings, the end serrations are joined together on the external part of adjoining tubular sections to provide a water tight seal. A secondary firm connection is made inside adjoining tubular sections to form a continues link. The floating sections are submerged systematically by ballasting their compartments with water ballast. For the final positioning water ballast will be adjusted inside these compartments to sink and position them. As shown in the drawing other sections are then towed, ballasted and submerged and then connected to the section already in place systematically with each of the end connectors to form a complete progressive underwater/under sea bed link. The tunnel sections is then buried under the seabed by land earth fill material trucked in by barges so that they do not re-float after removal of the water ballast from inside the sections. The transverse bulkheads 1, 2, 3,4 and 5 are then removed and a continuous connection will be made between the two ends thus forming the tunnel. Claim: 1. A process for the construction of underwater tunnels comprising, converting pre-constructed old ship hulls of the desired dimensions into tubular sections by cutting off unnecessary and undesirable portions of the ship in any conventional manner while retaining the water tight integrity of the suitable portions of their hulls, constructing water tight steel bulkheads inside the said tube sections while the hull is afloat, constructing another vertical bulkhead extending to the ceiling of the tunnel and running along the total length of the tube sections, sandblasting the exposed outer sections, providing end concrete connectors on each end of the said tubular sections by connecting steel serrations thereon, coating each end connector face with a thick coat of conventional sealants before installation to ensure that the steel plate serrations mesh with the face of the other end connector of the other hull section, and pressure forcing in any conventional manner further sealant in the gaps betweent he end connectors, lowering the finished tubular section onto concrete piling provide with concrete stools and located in a pre-dug trench in the seabed, wherein the steps of sandblasting, providing the end connectors, and coating of the exterior surface of the tubular section are done while the said hull tubular section is afloat. 2. A process as claimed in claim 1 wherein the ballasting of the tubular sections is done by using water ballast. 3. A process as claimed in claim 1 wherein the ballasting of the invention is done by using sand ballast. 4. A process as claimed in claim 1 wherein the external surface of the tunnel section is coated with a protective coating of gunnite/concrete in order to protect it from corrosion and in order to provide increased stability and strength. 5. A process as claimed in claim 1 wherein the interiors of the tubular sections are provided with utility, ventilation, electrical, drainage and escape conduits continuously and simultaneously while work is being done on the exteriors. 6. A process as claimed in claim 1 wherein the partitions in the existing compartments of the watertight hull tubular sections are removed after the tubular section is sunk in order to provide a continuous tunnel passageway. 7. A process as claimed in claim 1 wherein the end concrete connectors comprise steel plates welded to the main sections and filled with steel re-enforcing rods and concrete/cement fill. 8. A process as claimed in claim 1 and 7 wherein the ends of these serrations slightly protrude out of the ends. 9. A process as claimed in claim 1 and 7 wherein the rubber and bitumen are forced into a compact mass between the opposing steel serration's between the sections to form a water tight connection allowing little expansion or contraction. 10. A process as claimed in claim 1 wherein the conventional sealant used is selected from rubber, bitumen epoxy and the like. 11. A process for the construction of underwater tunnels substantially as herein described with reference to and as illustrated inn the accompanying drawings.

Documents:

1218-del-1999-abstract.pdf

1218-del-1999-claims.pdf

1218-del-1999-correspondence-others.pdf

1218-del-1999-correspondence-po.pdf

1218-del-1999-description (complete).pdf

1218-del-1999-drawings.pdf

1218-del-1999-form-1.pdf

1218-del-1999-form-19.pdf

1218-del-1999-form-2.pdf

1218-del-1999-form-3.pdf

1218-del-1999-gpa.pdf