METHOD FOR BUILDING A SHALLOW TUNNEL AT A WATER AREA BOTTOM AND A SYSTEM FOR TEMPORALLY DEWATERING A BOTTOM AREA

Abstract

 A method of building a shallow-depth tunnel at the bottom of a water area and a system used to implement it present a technology of driving a tunnel for vehicle traffic or other-purpose tunnel under the river channel or under the bottom of other shallow water area. They can be predominantly used to form a temporary enclosure for a closed bottom segment in the water area and the space above it throughout the depth of water.
A distinctive feature of the method is that a bottomless hydraulic enclosure with controlled buoyancy is used in it. This enclosure is made at a plant as a single closed structure capable of bearing on it detachable crane equipment, construction platforms and amenity rooms.

Description

Pertinent art

[0001] The present invention relates to hydraulic engineering, predominantly, to the technology of constructing a tunnel for highway traffic or other-purpose tunnel under the river channel or under the bottom of other shallow water area. Predominantly it can be used to form a temporary protection for a closed bottom segment in the water area and for the space above it throughout the depth of water.

Prior art

[0002] A method of forming a new land territory on the bottom of seas and oceans (see RU Patent No. 2044117, IC E01B 17/00, published on September 20, 1995) is known which includes enclosing an area of sea or ocean bottom along its perimeter by a main dam higher than the maximum water level, and further complete removal of water from the space enclosed by the dam. In parallel with each section of the main dam, a respective section of a protective single- or multiple-contour dam is set up linked in a pivot manner to one another with the help of reinforcing cofferdams. In the body of at least one dam and/or between the dams a system is created to transfer water flows of sea currents to its opposite side, while the lateral sea-facing surface of the main dam is made with a multiple-control ribbing positioned in parallel with the bottom in order to stabilize in depth the water flows going around the dam.

[0003] The known method is very complex to implement and requires considerable material and labor inputs.

[0004] A sheet-pile wall (see RU Patent No. 2185476, IC E02D 5/02, published on July 20, 2002) is known which contains piles with sheet-pile projections rigidly fixed to their outer surfaces, and sheet-pile interlocks, each made from two profile elements positioned with a clearance between them and connected to one another with the help of a stiffening rib, which forms a sheet-pile groove for placing a sheet-pile projection in it. Sheet-pile interlocks are united in pairs to form closing rod-like elements, each having two longitudinal sheet-pile grooves and installed in the wall between piles. Each closing rod-like element is made by welding from two channel bars whose shelves face one another and are positioned so as to form clearances between them, and from at least one stiffening rib positioned between channel bars.

[0005] To erect a sheet-pile wall in the form of a closed enclosing structure, it is necessary to use a high number of constituents, which greatly lengthens the time of completing construction work.

[0006] A method of building a tunnel in soft grounds (see RU Application No. 2001134688, IC E02D 29/00, published on August 20, 2003) is known which includes installing a pile enclosure before the formation of the starting and receiving foundation pits in the ground within the area of their location, which later protects excavation of ground in foundation pits.

[0007] To be implemented, the above method requires using a multitude of constituents from which the closed enclosing structure is made directly on the bottom segment, which takes a long construction time.

[0008] A sheet-pile wall (see RU Patent No. 2151236, IC E02D 5/08, published on June 20, 2002) is known consisting of undulating precast elements, each having shelves positioned on different sides from longitudinal axis of the wall in parallel with this axis with a displacement relative to each other and connected with each other by inclined walls positioned at obtuse angle to the shelves that are parallel with the longitudinal axis.

[0009] Using the known sheet-pile wall to erect a closed enclosing structure requires considerable labor costs and long time for its erection.

[0010] A method of building a shallow-depth tunnel at the bottom of a water area (see USSR author's certificate No. 1067142, IC E02D 5/20, published on January 15, 1984) is known which includes creating a temporary hydraulic enclosure from a set of casings formed from, e.g., metal sheet pile, each of these casings being element-wise erected, as the depth of the water area grows, along the perimeter of the closed bottom area selected. The result is the formation of a closed enclosing zone in the water area. Then water is removed from the enclosed space and, at the bottom inside it, construction work is carried out by a dry method to build the tunnel. Upon completion of construction work, the hydraulic enclosure is element-wise dismounted with possible further use of its elements.

[0011] This known technical solution fixes the task similar to the invention being applied for and contains the greatest number of common features. However, the major drawback of the known technical solution is the necessity to use many diversiform constituents from which a closed enclosing structure is made in the water medium directly on the bottom segment, which requires a long construction period.

[0012] A technical solution is known called "A system for temporary drainage of a bottom segment" (see USSR author's certificate No. 1067142, IC E02D 5/20, published on January 15, 1984). It realizes the aforementioned known method of building a low-depth tunnel at the bottom of a water area and presents a temporary closed hydraulic enclosure submerged to the bottom of the water area. This enclosure consists of a set of diversiform casings formed, e.g., from sheet piles and having elliptic, circular or parabolic outline in plan.

[0013] The known system consists of a set of isolate elements different both in form and making, which requires a long construction period to assemble them into a single structure in water, as well as high precision of assemblage thereof in complex hydrological conditions and, consequently, greater labor costs. This temporary hydraulic enclosure cannot be used as a vertically loaded structure in order to ensure the process of building the tunnel inside the enclosure.

Disclosure of the invention

[0014] The task of the technical solution being applied for is to create such a
method for building a shallow-depth tunnel at the bottom of a water area and realizing its systems, which would be simpler and more reliable and enable to build a shallow-depth tunnel for a short period of time, while the system could perform additional functions during the driving of the tunnel.

[0015] In what concerns the method, the task set is solved by using the method for building a shallow-depth tunnel at the bottom of a water area, which includes the fabrication of a single bottomless hydraulic enclosure with controlled buoyancy. The enclosure is further transported and placed in the tunnel's route, submerged to the bottom through decreasing its buoyancy and fixed at the bottom with the help of retainers and a system of anchors, thus forming a temporary hydraulic enclosure along the perimeter of the closed bottomsegment. The upper part of the hydraulic enclosure positioned above water level is horizontally flattened. Crane equipment and platforms for temporary storage of construction materials are placed thereon; then sheet-pile walls are erected within the enclosed space; after which the water is removed from the enclosed space; sea soil is excavated by way of digging a foundation pit followed by the creation of the tunnel's bearing pile field, on which a foundation mat is erected with precast or monolith ferroconcrete sections of the tunnel placed on it. After work is over within the enclosed space, the hydraulic enclosure is returned its initial buoyancy, separated from the bottom and transported to another tunnel construction site.

[0016] A bottomless floating dock can be used as a hydraulic enclosure.

[0017] The task set to find a system realizing the method is solved by making the temporary hydraulic enclosure as a single bottomless structure with controlled buoyancy and movable retainers in the form of knives along vertical walls.

[0018] A temporary hydraulic enclosure can be made as a bottomless floating dock.

[0019] Such technical solution enables to create a new method for building a shallow-depth tunnel within the water area, which, compared with similar-purpose known methods, has the following advantage, namely, a single shop-mounted reusable hydraulic enclosure. It is essential that said hydraulic enclosure has a feature absent in the prototype, namely, it can be a bearing structure, on which, e.g., crane equipment and platforms for temporary storage of construction materials can be placed.

[0020] In comparison with the known solution, the system applied for has essential distinctions consisting, first and foremost, in that a single shop-mounted structure is used as a temporary enclosure for the closed bottom segment.

[0021] From the state of the art, systems for temporary enclosure are known that are created in water medium at the bottom segment of a water area from a serially mounted set of diversiform elements. In our case, a hydraulic enclosure is shop-mounted as, e.g., a dock, to which the function of a temporary hydraulic enclosure is added.

Brief description of the drawings

[0022] The essence of the inventions is illustrated by the drawings, where:

• Fig. 1 shows the cross-section of a temporary hydraulic enclosure at the stage of tunnel construction;
• Fig. 2 shows the general view of the hydraulic enclosure in its transit position;
• Fig. 3 shows the general view of the hydraulic enclosure in axonometry at the stage of submergence to the bottom of the water area.

[0023] Practical application of the inventions being applied for is explained by the description below.

Best embodiment of the invention

[0024] The method proposed to build a shallow-depth tunnel at the bottom of a water area is implemented as follows:

First, single temporary hydraulic enclosure 1 with controlled buoyancy is fabricated at a plant, in particular, as a dock with no bottom part (see figs. 1, 2, 3). It can have, e.g., the following geometrical dimensions: 30 m wide (for navigating through draw spans of existing brides), 60 m long and 15 m high. Side towers 2 of enclosure 1 are made with the closed perimeter, each of the towers being, e.g., 3 m wide. Buoyancy cisterns 3 placed inside them ensure the transportation of enclosure 1 and its positioning on bottom 4 of the water area (see fig. 3). When such hydraulic enclosure is made at a plant, it is towed (fig. 2) through draw spans of bridges (not shown in the figure), placed in the tunnel's route, submerged to bottom 4 by decreasing its buoyancy, fixed with the help of sliding knives 5, and reliably fastened to the ground by a system of anchors. The upper part of enclosure 1 is horizontally flattened, which enables to place crane equipment and platforms for temporary storage of construction materials on this enclosure. The upper part of 1 can be flattened by way of planning bottom 4 of the water area and moving knives 5 out (see fig. 1). The upper part of enclosure 1 in this case rises above water level 7. To excavate seabed soil inside enclosure 1, sheet-pile walls 8 are erected along the perimeter of the future foundation pit. Water is then removed from the enclosed space and tunnel construction work is carried out using a dry cut-and-cover method. Such hydraulic enclosure 1 can serve as a place to moor floating cranes (not shown in the figure). Upon completion of construction work, hydraulic enclosure 1 is returned its initial buoyancy, separated from the bottom and transported to the next tunnel construction site (see fig. 2).

[0025] The proposed system for temporary drainage of the bottom segment used to realize the aforementioned method consists of a closed temporary hydraulic structure 1. This structure is made as a single bottomless structure with controlled buoyancy, e.g., in the form of a dock. Movable retainers, e.g., in the form of knives 5 are positioned on its internal walls (see fig. 1). Such system is used as described above. After the enclosed space has been drained, a foundation pit is dug out at the bottom of the water area; the tunnel's bearing pile field 9 is created on which foundation mat 10 is erected; and precast or monolith ferroconcrete sections of tunnel 11 are placed with their reliable joining and flashing ensured. Then a near-bottom protective cushion is dumped over tunnel 11 cover and move the system to a new tunnel 11 construction site.

Claims

1. A method of building a shallow-depth tunnel at the bottom of a water area, including the formation of a temporary hydraulic enclosure along the perimeter of a closed bottom segment and removal of water from the enclosed space; performance of construction work inside it using a dry method with further dismounting of the hydraulic enclosure, differing in that a single bottomless hydraulic enclosure with controlled buoyancy is produced, then transported and placed in the tunnel's route, submerged to the bottom through reducing its buoyancy and fixed at the bottom with the help of retainers and a system of anchors, the upper part of the hydraulic enclosure rising above water level is horizontally flattened; and crane equipment and platforms for temporary storage of construction materials are put on it; then sheet-pile walls are erected inside the enclosed space; after which water is removed from the enclosed space; seabed soil is excavated by digging out a foundation pit; and then the tunnel's bearing pile field is created, on which a foundation mat is installed with the tunnel's precast or monolith ferroconcrete sections placed on it; upon completion of construction work the hydraulic enclosure is returned its initial buoyancy, separated from the bottom and transported to the next tunnel construction site.

2. A method according to p. 1, wherein a bottomless floating dock is used as a hydraulic enclosure.

3. A system for temporary drainage of the bottom segment used to exercise the method according to p.1, wherein the temporary hydraulic enclosure is made as a single bottomless structure with controlled buoyancy and with movable retainers in the form of knives on vertical walls.

4. A system according to p. 3, wherein a bottomless floating dock is used as a temporary hydraulic enclosure.

Drawing