An assembled bridge crossing a deep and large water-filled cave and a construction method thereof

Abstract

The application discloses a kind of assembled bridge and construction method for crossing deep and large water solution cave, using assembled bridge, all components are using steel structure, each component is according to its stress characteristics and cost to select corresponding type and size.Except that one side of inclined beam and upper longitudinal beam is anchored in solution cave wall rock, all steel components and connecting pieces are connected by bolts, different components are connected using different connecting pieces, component connection design is scientific and reasonable, and has strong stability and practicability.The application is easy to install and disassemble, which is beneficial to later maintenance and reconstruction.

Description

Technical Field

[0001] This invention relates to the field of karst cave treatment technology, specifically to a prefabricated bridge spanning a deep, water-filled karst cave and its construction method. Background Technology

[0002] When encountering shallowly buried karst caves during road construction in karst areas, the excavation of the overlying layer exposes the caves. Current solutions primarily involve full filling and bridge construction. However, when the underground karst caves are deep, large, and contain water, backfilling is either impossible or prohibitively expensive. When using conventional bridges to cross karst caves, the bridge pile foundations must be supported at the bottom of the cave, which presents significant construction challenges, complex processes, difficulty in quality control, long construction periods, and high costs.

[0003] To avoid the need for bridge pile foundation construction, patent document [CN112855168A] discloses a method for constructing a suspension bridge-type tunnel spanning a very large karst cave. However, its suspension structure needs to be anchored in the rock strata at the top of the karst cave, which is obviously unsuitable for bridges in open-air karst caves. Patent document [CN204282319U] discloses an arch bridge-type hydraulic tunnel structure spanning a karst cave. Although it uses an arch structure to span the karst cave to avoid pile foundation engineering, the arch ring is constructed using cast-in-place reinforced concrete. The construction of the arch ring inside the karst cave is difficult, complex, has a long construction period, and is costly.

[0004] Therefore, it is necessary to propose a new bridge structure and corresponding construction method for situations where road excavation requires crossing deep, water-filled karst caves. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the technical problem this invention aims to solve is to provide a prefabricated bridge spanning a deep, water-filled karst cave and its construction method. This structure is assembled from prefabricated components. Compared to other fully infilled and conventional bridge spanning methods, it eliminates the need for piers and foundation structures, fully utilizing the cave wall rock strata as the bridge's supporting structure. This significantly saves construction time and filling materials, and reduces project costs.

[0006] The technical solution adopted by the present invention to solve the aforementioned technical problem is as follows:

[0007] A prefabricated bridge spanning a deep, water-filled karst cave, the bridge comprising:

[0008] The inclined beams, using precast steel-concrete composite structures, provide support for the entire bridge. One end of each of the two inclined beams is anchored in the rock strata of the mountain, while the other end connects the two inclined beams together at the mid-span. At this point, the two inclined beams and the deep, large, water-filled karst cave are arranged in a triangular pattern.

[0009] The longitudinal beams are laid out along the length of the bridge and are divided into upper and lower longitudinal beams. They are made of U-shaped steel. The two ends of the lower longitudinal beam 06 are supported at the junction of the inclined beam and the rock wall, and the two ends of the upper longitudinal beam 05 are anchored in the rock strata of the mountain.

[0010] The vertical rod is a vertical structure, consisting of an upper vertical rod 03 and a lower vertical rod 04 of different lengths, both made of I-beams. The upper vertical rod connects the upper longitudinal beam 05 and the diagonal beam, while the lower vertical rod 04 connects the lower longitudinal beam 06 and the diagonal beam.

[0011] The diagonal brace, which is an oblique structure and made of I-beams, is used to connect the diagonal beam and the lower longitudinal beam.

[0012] The crossbeam is a transverse structure, divided into an upper crossbeam 08, a middle crossbeam 09, and a lower crossbeam 010, all made of I-beam steel. The upper crossbeam is used to connect multiple upper longitudinal beams in the transverse direction, the middle crossbeam is used to connect multiple diagonal beams in the transverse direction, and the lower crossbeam is used to connect multiple lower longitudinal beams in the transverse direction.

[0013] Bridge deck steel plate 011 is located on top of the upper longitudinal beam and upper transverse beam. The upper longitudinal beam and upper transverse beam are welded with bolts at intervals. Corresponding holes are arranged on the bridge deck steel plate. When installing the bridge deck steel plate, multiple upper longitudinal beams are set in the width direction of the bridge. The multiple upper longitudinal beams and multiple upper transverse beams connecting adjacent upper longitudinal beams are fixed together with the bridge deck steel plate 011 by the cooperation of bolts and holes.

[0014] Asphalt pavement 012 is built on the steel plate of the bridge deck for vehicles to travel on.

[0015] The bridge deck steel plate 011 is composed of a number of small steel plates, each of which is rectangular in structure. The long side of each small steel plate is equal to the width of the bridge. All the small steel plates are spliced ​​together along the length of the bridge to form the entire bridge deck steel plate.

[0016] The working principle of the bridge is as follows: Inclined beams and upper longitudinal beams bear the entire load of the bridge. The inclined beams are obliquely anchored in the rock strata on both sides of a deep, water-filled karst cave. The two inclined beams share a common end point, forming a triangular skeleton, which is the largest load-bearing component and mainly bears downward pressure. Under the bridge load, the inclined beams are pressed into the mountain without damaging the mountain's structure, increasing the stability of the bridge support. Simultaneously, the left and right inclined beams and the lower longitudinal beam at the bottom form a large triangle. Several inclined bars are installed in the opposite direction to the corresponding inclined beams, forming small triangles between the inclined bars and vertical bars, and between the inclined bars and the inclined beams, and between the inclined bars and the lower longitudinal beams. The combined use of large, medium, and small triangles increases the overall stability and load-bearing capacity.

[0017] The bridge is equipped with multiple nodes, including node 1, node 2, node 3, node 4, node 5, node 6, and node 7.

[0018] The first and second nodes are used to connect the lower longitudinal beam, the lower vertical bar, the diagonal bar and the horizontal beam. The connection ends of the diagonal bar, the lower vertical bar and the horizontal beam to the lower longitudinal beam are all welded with steel plates. The steel plates are provided with round holes. The lower longitudinal beam is made of U-shaped steel. The bottom surface of the U-shaped steel is provided with round holes along the length direction that correspond to the positions of the round holes on the steel plate. The connection is achieved by using bolts passing through the round holes on the steel plate and the round holes on the bottom surface of the U-shaped steel.

[0019] The second node is connected to only one diagonal bar, while the first node is connected to two diagonal bars. The two diagonal bars are symmetrically arranged with the longest lower vertical bar as the center. Bolt holes are provided on the side of the lower longitudinal beam U-shaped steel for connecting it to the adjacent lower cross beam by bolts.

[0020] The third node is used to connect the lower longitudinal beam, the lower vertical rod, and the lower horizontal beam. The connection end of the lower vertical rod and the lower longitudinal beam is welded with a steel plate. The steel plate has at least two round holes. The bottom surface of the U-shaped steel of the lower longitudinal beam has round holes corresponding to those of the steel plate. The connection is achieved by bolts passing through the round holes of the steel plate and the round holes of the U-shaped steel. The side of the U-shaped steel of the lower longitudinal beam is provided with bolt holes for connecting it to the adjacent lower horizontal beam by bolts.

[0021] The fourth node 4 is connected to the lower longitudinal beam, the inclined beam and the lower transverse beam through the first connector. The lower longitudinal beam, the lower transverse beam and the connection end of the first connector are welded with steel plates. The steel plates are provided with round holes. The first connector is provided with screw holes corresponding to the round holes of the steel plates. The connection is achieved by using bolts passing through the round holes of the steel plates and the screw holes of the first connector.

[0022] The fifth node is connected to the upper longitudinal beam, the longest lower vertical rod, and the inclined beam through the second connector. The connection end of the longest lower vertical rod and the second connector is welded with a steel plate. The steel plates at the connection ends of the upper longitudinal beam and the longest lower vertical rod are provided with round holes. The second connector is provided with screw holes corresponding to the round holes on the upper longitudinal beam and the steel plate. The connection is achieved by using bolts passing through the round holes and the corresponding screw holes on the second connector.

[0023] The first connector is an irregular structure, with a cuboid shape and an inclined through hole inside, used to connect the inclined beam, the lower longitudinal beam and the lower cross beam, or to connect the inclined beam, the upper and lower vertical bars, the inclined bar and the cross beam;

[0024] The second connector is an irregular structure, divided into left and right parts. The second connector is a symmetrical structure, and both left and right parts are hollow steel components with oblique circular holes of a size that matches the diameter of the oblique beam.

[0025] The sixth node 6 is used to connect the upper longitudinal beam, the upper vertical rod and the upper horizontal beam. The upper vertical rod and the upper horizontal beam are connected to the upper longitudinal beam by welding steel plates. The steel plates are provided with round holes. The bottom and side surfaces of the upper longitudinal beam U-shaped steel are provided with round holes corresponding to the steel plates. The connection is achieved by using bolts to pass through the round holes of the steel plates and the round holes of the U-shaped steel.

[0026] The seventh node 7 is connected to the inclined beam, inclined rod, upper vertical rod, lower vertical rod and middle horizontal beam through the first connector. The connection ends of the upper and lower vertical rods, inclined rods and middle horizontal beam to the first connector are all welded with steel plates.

[0027] The first connector is divided into upper and lower parts and is fixed to the inclined beam by bolts. When the upper and lower parts of the first connector are put together, an inclined through hole for installing the inclined beam can be formed in the middle. The top surface of the upper part is provided with two screw holes, and the left and right sides are provided with screw holes for fixing to the lower or middle crossbeam. An extension is provided at the bottom of the left and right sides. The front surface of the lower part is provided with two rows of symmetrically arranged screw holes for fixing to the steel plate at the end of the U-shaped steel of the lower longitudinal beam. Each row of screw holes has two screw holes. The two rows of screw holes are distributed near the edge of the front surface of the lower part. The bottom of the lower part is also provided with two screw holes. When the first connector is used at the fourth node, the two screw holes on the top and bottom surfaces of the upper and lower parts are idle. When the first connector is used at the seventh node, the two screw holes on the top and bottom surfaces of the upper and lower parts are used to connect the upper and lower vertical bars respectively. An extension is also provided at the upper end of the left and right sides of the lower part. After the upper and lower parts are covered by each other, they are connected into a whole by bolts through the corresponding screw holes on the extension and the steel pipe is wrapped and fixed.

[0028] A number of vertical screw holes are provided on the top surface of the second connector for fixing to the upper longitudinal beam, and a number of vertical screw holes are provided on the bottom surface for fixing to the steel plate on the longest lower vertical rod; multiple sets of horizontal screw holes are arranged on the second connector at the positions above and below the oblique circular hole 1104, and the horizontal screw holes are used to connect the left and right oblique beams into one piece by bolts; two sets of transverse screw holes 1101 are symmetrically arranged on the left and right sides of the upper center of the second connector, and the transverse screw holes are used to connect the oblique beam to the upper cross beam into one piece by bolts. The left and right parts of the second connector are inserted into the two oblique beams, and then the left and right parts are fixed to fix the left and right oblique beams.

[0029] The thickness of the second connector, which fits into the left and right parts of the inclined beam, is 10-20cm.

[0030] The large karst caves mentioned refer to those with a width exceeding 20m and a height exceeding 10m, and the bridge spans are 20m-50m; all components of the bridges are made of prefabricated materials to achieve the purpose of rapid assembly construction.

[0031] This invention also protects a construction method for the above-mentioned prefabricated bridge spanning a deep, water-filled karst cave, the construction method comprising the following steps:

[0032] Step 1: First, determine the length and width of the bridge based on the road grade, road surface width and height, and the size of the karst cave. Then, design the materials and dimensions of each component of the prefabricated bridge.

[0033] Step 2: Measure and lay out the anchoring position of the inclined beam, then drill holes in the cave wall, clean the debris in the holes, insert the steel pipe concrete inclined beam into the drill holes, connect the other ends of the left and right inclined beams with bolts in the middle of the span, and finally pour micro-expansion cement grout into the drill holes to fix the inclined beams.

[0034] Step 3: Measure and lay out the anchoring position of the upper longitudinal beam, then drill holes in the cave wall, clean the debris in the holes, insert the U-shaped steel upper longitudinal beam into the holes, and finally pour micro-expansion cement grout into the holes to fix the upper longitudinal beam.

[0035] Step 4: Install the lower longitudinal beam and connect it to the diagonal beam;

[0036] Step 5: Install the upper and lower vertical bars, and connect the upper and lower vertical bars of different lengths to the upper longitudinal beam, lower longitudinal beam, and diagonal beam;

[0037] Step 6: Install the diagonal bracing, connecting it to the lower longitudinal beam, diagonal beam, and vertical bracing;

[0038] Step 7: The diagonal beams, longitudinal beams, vertical bars and diagonal bars are combined to form a truss. Multiple trusses are arranged horizontally, and crossbeams are installed. The different horizontal trusses are connected by the upper, middle and lower crossbeams.

[0039] Step 8: Install the bridge deck steel plates and connect them to the upper longitudinal beams and upper transverse beams using bolts;

[0040] Step 9: Lay the asphalt pavement of the bridge deck in layers to complete the construction of the prefabricated bridge.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] 1. The bridge structure design of this invention is novel and unique, with scientifically and rationally arranged components and clear load transmission. The inclined beams and upper longitudinal beams bear the entire load of the bridge, while other components are used to strengthen the connection between various parts of the bridge to improve overall rigidity. The most stressed component is the inclined beam, which is a compression member and uses steel-concrete composite to take advantage of its strong compressive strength. Furthermore, the two ends of the inclined beam are anchored in the mountain rock strata, utilizing the friction between the inclined beam and the rock strata and the end resistance of the beam to withstand sufficient pressure, fully utilizing the strong compressive strength of the karst rock strata. The upper longitudinal beam is a secondary stress-bearing component, using U-shaped steel to bear tensile stress and can share part of the bridge load. Anchored at both ends in the mountain rock strata, it provides pull-out resistance through the friction between the U-shaped steel and the rock strata, providing support for the bridge. The lower longitudinal beam is a tension member, using U-shaped steel; the vertical members are compression members, using I-beams; the inclined members are partially compressed and partially tensile, using I-beams; and the crossbeams are connecting members, using I-beams.

[0043] 2. This invention employs a prefabricated bridge design, with all components made of steel. The type and size of each component are selected based on its stress characteristics and cost. Except for the inclined beams and the upper longitudinal beams, which are anchored to one side of the cave wall rock strata, all steel components and connectors are bolted together. Different connectors are used for different components, resulting in a scientifically sound and practical component connection design. Furthermore, this invention is easy to install and disassemble, facilitating future maintenance and modifications.

[0044] 3. The bridge of the present invention has strong stability and small deformation. The inclined beam, lower longitudinal beam, lower vertical bar and inclined bar in the main load-bearing components form a triangular structure. Compared with other types of bridges, the triangular structure has the best stability.

[0045] 4. The present invention has a simple and lightweight structure, and the components are easy to connect. It avoids the construction of pile foundations for conventional bridges. The construction method can realize node connection, which is simple, fast to install, and low in construction cost. It is especially suitable for deep and large water-filled karst caves. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the longitudinal structure of the prefabricated bridge spanning a deep, water-filled karst cave, as described in this invention.

[0047] Figure 2 This is a schematic cross-sectional view of the prefabricated bridge spanning a deep, water-filled karst cave, as described in this invention.

[0048] Figure 3(a) is a schematic diagram of the main structure of the prefabricated bridge spanning a deep, water-filled karst cave of the present invention after the installation of the inclined beam of the first connecting component.

[0049] Figure 3(b) is a top view of the upper part of the first connector in the prefabricated bridge spanning a deep, water-filled karst cave according to the present invention.

[0050] Figure 3(c) is a side view of the first connecting component in the prefabricated bridge spanning a deep, water-filled karst cave according to the present invention.

[0051] Figure 4(a) is a schematic diagram of the main structure of the second connector in the prefabricated bridge spanning a deep, water-filled karst cave according to the present invention.

[0052] Figure 4(b) is a left-side structural schematic diagram of the second connector in the prefabricated bridge spanning a deep, water-filled karst cave according to the present invention.

[0053] Figure 4(c) is a top view of the second connector in the prefabricated bridge spanning a deep, water-filled karst cave according to the present invention.

[0054] Figure 5 This is a schematic diagram of the first node 1 of the prefabricated bridge spanning a deep, water-filled karst cave according to the present invention.

[0055] Figure 6This is a schematic diagram of the second node 2 of the prefabricated bridge spanning a deep, water-filled karst cave according to the present invention.

[0056] Figure 7 This is a schematic diagram of the third node 3 of the prefabricated bridge spanning a deep, water-filled karst cave according to the present invention.

[0057] Figure 8 This is a schematic diagram of the fourth node 4 of the prefabricated bridge spanning a deep, water-filled karst cave according to the present invention.

[0058] Figure 9 This is a schematic diagram of the fifth node 5 of the prefabricated bridge spanning a deep, water-filled karst cave according to the present invention.

[0059] Figure 10 This is a schematic diagram of the sixth node 6 of the prefabricated bridge spanning a deep, water-filled karst cave according to the present invention.

[0060] Figure 11 This is a schematic diagram of the seventh node 7 of the prefabricated bridge spanning a deep, water-filled karst cave according to the present invention.

[0061] Figure 12 This is a plan view of the small steel plates in the bridge deck steel plate of the prefabricated bridge spanning a deep, water-filled karst cave according to the present invention.

[0062] In the diagram, 01 is the left inclined beam, 02 is the right inclined beam, 03 is the upper vertical bar, 04 is the lower vertical bar, 05 is the upper longitudinal beam, 06 is the lower longitudinal beam, 07 is the inclined bar, 08 is the upper crossbeam, 09 is the middle crossbeam, 010 is the lower crossbeam, 011 is the bridge deck steel plate, 012 is the asphalt pavement, 013 is the karst cave, and 014 is the bolt.

[0063] 1 First node, 2 Second node, 3 Third node, 4 Fourth node, 5 Fifth node, 6 Sixth node, 7 Seventh node, 8 Filling concrete, 9 Steel pipe, 10 First connector, 11 Second connector, 12 Steel plate;

[0064] 101 Upper part, 102 Extension, 103 Lower part, 104 Inclined through hole; 1101 Horizontal screw hole, 1102 Vertical screw hole, 1103 Horizontal screw hole, 1104 Oblique round hole;

[0065] 0111 connects to the bolt hole on the upper crossbeam, and 0112 connects to the bolt hole on the upper longitudinal beam. Detailed Implementation

[0066] The present invention will be further explained below with reference to the embodiments and accompanying drawings, but this is not intended to limit the scope of protection of this application.

[0067] This invention comprises two parts: a prefabricated bridge structure spanning a deep, water-filled karst cave and a construction method thereof.

[0068] This invention is primarily applicable to road excavation spanning deep, water-bearing karst caves. Large karst caves generally refer to those with a width exceeding 20m and a height exceeding 10m. Bridge spans between 20m and 50m are suitable, and the cave height must exceed 10m. This patented method is unsuitable for caves that are too small. The technical solution of this application avoids backfilling the karst cave and pile foundation construction, resulting in lower costs, faster construction speed, more convenient construction, and better economic efficiency.

[0069] This invention employs a prefabricated bridge design, which is novel and scientific, and clearly defines the load transmission mechanism.

[0070] This invention relates to a prefabricated bridge spanning a deep, water-filled karst cave (see...). Figure 1-2 The bridge includes:

[0071] The inclined beams, using precast steel-concrete composite structures, provide support for the entire bridge. One end of each of the two inclined beams is anchored in the rock strata of the mountain, and the other end is connected to the two inclined beams at the fifth node 5 in the middle of the span. At this time, the two inclined beams and the deep water-filled karst cave 013 are arranged in a triangle. The friction between the inclined beams and the rock strata and the resistance at the beam ends can withstand sufficient pressure.

[0072] The longitudinal beams are laid out along the length of the bridge and are divided into upper longitudinal beams and lower longitudinal beams. They are made of U-shaped steel. The two ends of the lower longitudinal beam 06 are supported at the junction of the inclined beam and the rock wall by the fourth node 4. The two ends of the upper longitudinal beam 05 are anchored in the rock strata of the mountain.

[0073] The vertical rod is a vertical structure, consisting of an upper vertical rod 03 and a lower vertical rod 04 of different lengths, both made of I-beams. The upper vertical rod connects the upper longitudinal beam 05 and the diagonal beam (01 or 02), and the lower vertical rod 04 connects the lower longitudinal beam 06 and the diagonal beam (01 or 02).

[0074] The diagonal brace, which is an inclined structure made of I-beams, is used to connect the inclined beam and the lower longitudinal beam, thereby improving the rigidity and stability of the entire bridge.

[0075] The crossbeams are transverse structures, consisting of an upper crossbeam 08, a middle crossbeam 09, and a lower crossbeam 010, all made of I-beams. The upper crossbeams connect multiple upper longitudinal beams in the transverse direction, the middle crossbeams connect multiple diagonal beams in the transverse direction, and the lower crossbeams connect multiple lower longitudinal beams in the transverse direction to improve the transverse stability of the entire bridge.

[0076] Bridge deck steel plate 011 is located on top of the upper longitudinal beam and upper transverse beam. The upper longitudinal beam and upper transverse beam are welded with bolts at intervals. Corresponding holes are arranged on the bridge deck steel plate. When installing the bridge deck steel plate, multiple upper longitudinal beams are set in the width direction of the bridge. The multiple upper longitudinal beams and multiple upper transverse beams connecting adjacent upper longitudinal beams are fixed together with the bridge deck steel plate 011 by the cooperation of bolts and holes.

[0077] Asphalt pavement 012 is built on the steel plate of the bridge deck for vehicles to travel on.

[0078] The bridge deck steel plate 011 is composed of a number of small steel plates, the small steel plates (see...) Figure 12 The bridge deck has a rectangular structure, with the long side of each small steel plate equal to the width of the bridge. All small steel plates are sequentially spliced ​​along the length of the bridge to form the entire bridge deck steel plate. The small steel plates have a number of bolt holes 0112 for connecting to the longitudinal beams along the length of the bridge, and two sets of bolt holes 0111 for connecting to the transverse beams along the width of the bridge. In this invention, the length of the bridge is defined as longitudinal, and the width of the bridge as transverse. The use of small steel plates in a splicing manner facilitates prefabricated construction. In this embodiment, the size of the small steel plates is designed according to the width of the bridge, and the number of small steel plates is determined according to the length of the bridge.

[0079] The working principle of the bridge of this invention is as follows:

[0080] The entire load of the bridge is borne by inclined beams and upper longitudinal beams. The inclined beams are obliquely anchored in the rock strata on both sides of a deep, water-filled karst cave. The two inclined beams share a common end point, forming a triangular skeleton, which is the largest load-bearing component and mainly bears the downward pressure. Under the bridge load, the inclined beams are pressed into the mountain without damaging the mountain structure, thus increasing the stability of the bridge support. At the same time, the left and right inclined beams and the lower longitudinal beam at the bottom form a large triangle. Meanwhile, several inclined bars that are inclined in the opposite direction to the corresponding inclined beams form small triangles between the inclined bars and the vertical bars and the lower longitudinal beams, and larger triangles between the inclined bars and the inclined beams and the lower longitudinal beams. The combined use of large, medium and small triangles increases the overall strength and load-bearing capacity.

[0081] The most stressed component is the inclined beam, which is a compression member and is constructed of steel-concrete composite. The upper longitudinal beam is a secondary load-bearing component, constructed of U-shaped steel, which bears tensile stress and can share part of the bridge load. Both ends are anchored in the mountain rock strata, providing pull-out resistance through the friction between the U-shaped steel and the rock strata, thus supporting the bridge. The lower longitudinal beam is a tension member, also constructed of U-shaped steel; the vertical members are compression members, constructed of I-beams; the inclined members are partially compressed and partially tensioned, also constructed of I-beams; and the crossbeams are connecting members, also constructed of I-beams. The coordination of all components and their connections forms a unified whole. Combined with other connecting components, this strengthens the connections between the bridge parts, improving overall rigidity. This allows the bridge of this application to achieve high-strength, low-cost use in deep, water-filled karst caves, fully utilizing the strong compressive strength of the karst rock strata.

[0082] The nodes mentioned above are the connecting structures of the rods, including the first node 1, the second node 2, the third node 3, the fourth node 4, the fifth node 5, the sixth node 6, and the seventh node 7;

[0083] The first node 1 and the second node 2 are used to connect the lower longitudinal beam, the lower vertical rod, the diagonal rod and the cross beam. The connecting ends of the diagonal rod, the lower vertical rod and the cross beam are all welded with steel plates. The steel plates have round holes. The lower longitudinal beam is made of U-shaped steel. The bottom surface of the U-shaped steel has round holes along the length direction that correspond to the positions of the round holes on the steel plate. The connection is achieved by using bolts passing through the round holes on the steel plate and the round holes on the bottom surface of the U-shaped steel.

[0084] First node 1 (see Figure 5 The structure connects two diagonal braces, symmetrically arranged around the longest lower vertical brace. A steel plate connects the lower vertical brace to the lower longitudinal beam, with two circular holes on the plate to enhance the connection. The circular holes are positioned near the center of the lower vertical brace to further improve overall connectivity. Bolt holes are located on the side of the U-shaped lower longitudinal beam for bolting to the adjacent lower crossbeam. A steel plate is also placed at the connection end of the lower crossbeam when connecting to the lower longitudinal beam. The lower vertical brace and lower longitudinal beam are connected within the truss, while the lower crossbeam and lower longitudinal beam are connected laterally.

[0085] Second node 2 (see Figure 6 The difference between this node and the first node is that it only connects to one diagonal bar.

[0086] The third node 3 (see Figure 7 This is used to connect the lower longitudinal beam, lower vertical rod, and lower horizontal beam. The connection ends of the lower vertical rod, lower horizontal beam, and lower longitudinal beam are all welded with steel plates. The steel plates have at least two round holes. The bottom surface of the U-shaped steel of the lower longitudinal beam has round holes corresponding to those in the steel plates. The connection is achieved by using bolts passing through the round holes in the steel plates and the round holes in the U-shaped steel. The side of the U-shaped steel of the lower longitudinal beam has bolt holes for connecting it to the adjacent lower horizontal beam as a whole by bolts.

[0087] The fourth node 4 is connected to the lower longitudinal beam, the inclined beam and the lower transverse beam through the first connector. The connection ends of the lower longitudinal beam, the lower transverse beam and the first connector 10 are all welded with steel plates. The steel plates are provided with round holes. The first connector is provided with screw holes corresponding to the round holes of the steel plates. The connection is achieved by using bolts passing through the round holes of the steel plates and the screw holes of the first connector.

[0088] The first connector is an irregularly shaped structure, rectangular in shape, with an inclined through hole 104 inside for connecting the inclined beam, lower longitudinal beam, and lower transverse beam, or connecting the inclined beam, upper and lower vertical rods, inclined rods, and transverse beam. It is divided into an upper part 101 and a lower part 103, and is fixed to the inclined beam by bolts. Figures 3(a)-3(c) show three views of one embodiment of the first connector. When the upper and lower parts of the first connector are put together, an inclined through hole 104 for installing the steel pipe 9 can be formed in the middle. The steel pipe 9 is filled with concrete 8, and the steel pipe 9 and the filling concrete 8 constitute the inclined beam. The top surface of the upper part is provided with two screw holes, and the left and right sides are provided with one screw hole. The bottom is provided with an extension 102; the front of the lower part is provided with two symmetrical rows of screw holes, each row of screw holes has two screw holes, the two rows of screw holes are distributed near the edge of the front of the lower part, and the bottom of the lower part is also provided with two screw holes (when the first connector is used at the fourth node, the two screw holes on the top and bottom of the upper and lower parts are idle; when the first connector is used at the seventh node, the two screw holes on the top and bottom of the upper and lower parts are used to connect the upper and lower vertical rods respectively). The upper ends of the left and right sides of the lower part are also provided with extensions 102. After the upper and lower parts are covered by each other, they are connected into a whole by bolts through the corresponding screw holes on the extensions, and the steel pipe is wrapped and fixed. The first connector has a total of 10 screw holes. The two rows of screw holes on the front of the lower part are used to fix it to the steel plate at the end of the U-shaped steel of the lower longitudinal beam, and the screw holes on the left and right sides of the upper part of the first connector are used to fix it to the lower crossbeam or the middle crossbeam.

[0089] The fifth node 5 is connected to the upper longitudinal beam, the longest lower vertical rod and the inclined beam through the second connector. The connection end of the longest lower vertical rod and the second connector 11 is welded with a steel plate. The upper longitudinal beam and the steel plate are provided with round holes. The second connector is provided with screw holes corresponding to the round holes on the upper longitudinal beam and the steel plate. The connection is achieved by using bolts passing through the round holes and the corresponding screw holes on the second connector.

[0090] The second connector is an irregularly shaped structure, divided into left and right parts. The second connector has a symmetrical structure (see Figures 4(a)-4(c)). Both left and right parts are hollow steel components, with oblique circular holes 1104, the size of which matches the diameter of the inclined beam. Several vertical screw holes 1102 are provided on the top surface of the second connector for fixing to the upper longitudinal beam, and several vertical screw holes 1102 are provided on the bottom surface for fixing to the steel plate on the longest lower vertical rod. Multiple sets of horizontal screw holes 1103 are arranged on the second connector above and below the oblique circular holes 1104. These horizontal screw holes are used to connect the left and right inclined beams into one unit using bolts. Two sets of transverse screw holes 1101 are symmetrically arranged at the upper center of the second connector. These transverse screw holes are used to connect the inclined beam to the upper crossbeam into one unit using bolts. The left and right parts of the second connector are fitted onto the two inclined beams, and then the left and right parts are fixed to secure the left and right inclined beams. The second connector has 40 screw holes, 20 on each side.

[0091] The thickness of the second connector, which fits into the left and right portions of the inclined beam, is 10-20cm. One end of the inclined beam is anchored first, and the other end of the left and right inclined beams is supported and overlapped together by the second connector, so that the entire bridge bears the force and the left and right inclined beams will not detach from the second connector.

[0092] The sixth node 6 is used to connect the upper longitudinal beam, the upper vertical rod and the upper horizontal beam. The upper vertical rod and the upper horizontal beam are connected to the upper longitudinal beam by welding steel plates. The steel plates are provided with round holes. The bottom and side surfaces of the upper longitudinal beam U-shaped steel are provided with round holes corresponding to the steel plates. The connection is achieved by using bolts to pass through the round holes of the steel plates and the round holes of the U-shaped steel.

[0093] The seventh node 7 is connected to the inclined beam, inclined rod, upper vertical rod, lower vertical rod, and middle horizontal beam via the first connector. The upper and lower vertical rods, inclined rods, and middle horizontal beam are all welded to the connection ends of the first connector with steel plates. The steel plates have round holes. The top and bottom screw holes of the upper and lower parts of the first connector are respectively connected to the upper and lower vertical rods by bolts. The screw holes on the left and right sides of the upper part of the first connector are used to connect to the middle horizontal beam. The inclined rod is connected to the front screw hole of the lower part of the first connector.

[0094] This invention also protects the construction method of the aforementioned prefabricated bridge spanning a deep, water-filled karst cave, comprising the following steps:

[0095] Step 1: First, determine the length and width of the bridge based on the road grade, road surface width and height, and the size of the karst cave. Then, design the materials and dimensions of each component of the prefabricated bridge.

[0096] Step 2: Measure and lay out the anchoring position of the inclined beam, then drill holes in the cave wall, clean the debris in the holes, insert the steel pipe concrete inclined beam into the drill holes, connect the other ends of the left and right inclined beams with bolts in the middle of the span, and finally pour micro-expansion cement grout into the drill holes to fix the inclined beams.

[0097] Step 3: Measure and lay out the anchoring position of the upper longitudinal beam, then drill holes in the cave wall, clean the debris in the holes, insert the U-shaped steel upper longitudinal beam into the holes, and finally pour micro-expansion cement grout into the holes to fix the upper longitudinal beam.

[0098] Step 4: Install the lower longitudinal beam and connect it to the inclined beam through the fourth node 4;

[0099] Step 5: Install the upper and lower vertical bars, and connect the upper and lower vertical bars to the upper longitudinal beam, lower longitudinal beam, and diagonal beam through the seventh node, fifth node, sixth node, first node, second node, and third node;

[0100] Step 6: Install the diagonal bracing, and connect the diagonal bracing to the lower longitudinal beam, diagonal beam, and vertical bracing through the reserved screw holes on the corresponding nodes;

[0101] Step 7: The diagonal beams, longitudinal beams, vertical bars and diagonal bars are combined to form a truss. Multiple trusses are arranged horizontally, and crossbeams are installed. The different horizontal trusses are connected by the upper, middle and lower crossbeams.

[0102] Step 8: Install the bridge deck steel plates and connect them to the upper longitudinal beams and upper transverse beams using bolts;

[0103] Step 9: Lay the asphalt pavement of the bridge deck in layers to complete the construction of the prefabricated bridge.

[0104] All components in the governance structure are made of prefabricated materials (prefabricated in a steel structure processing plant), achieving the goal of rapid prefabricated construction.

[0105] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A prefabricated bridge spanning a deep, water-filled karst cave, characterized in that, The bridge includes: The inclined beams, using precast steel-concrete composite structures, provide support for the entire bridge. One end of each of the two inclined beams is anchored in the rock strata of the mountain, while the other end connects the two inclined beams together at the mid-span. At this point, the two inclined beams and the deep, large, water-filled karst cave are arranged in a triangular pattern. The longitudinal beams are arranged along the length of the bridge and are divided into upper longitudinal beams and lower longitudinal beams. They are made of U-shaped steel. The two ends of the lower longitudinal beams are supported at the junction of the inclined beams and the rock wall, and the two ends of the upper longitudinal beams are anchored in the rock strata of the mountain. The upper longitudinal beams and the two inclined beams are fixedly connected at the common end points at the mid-span to form an integral load-bearing component. The vertical rod is a vertical structure, consisting of upper and lower vertical rods of different lengths, both made of I-beams. The upper vertical rod connects the upper longitudinal beam and the diagonal beam, and the lower vertical rod connects the lower longitudinal beam and the diagonal beam. The diagonal brace, which is an oblique structure and made of I-beams, is used to connect the diagonal beam and the lower longitudinal beam. The crossbeam is a transverse structure, consisting of an upper crossbeam, a middle crossbeam, and a lower crossbeam, all made of I-beams. The upper crossbeam connects multiple upper longitudinal beams in the transverse direction, the middle crossbeam connects multiple diagonal beams in the transverse direction, and the lower crossbeam connects multiple lower longitudinal beams in the transverse direction. The bridge deck steel plate is located on top of the upper longitudinal beams and upper transverse beams. The upper longitudinal beams and upper transverse beams are welded with bolts at intervals. Corresponding holes are arranged on the bridge deck steel plate. When installing the bridge deck steel plate, multiple upper longitudinal beams are set in the width direction of the bridge. The multiple upper longitudinal beams and multiple upper transverse beams connecting adjacent upper longitudinal beams are fixed together with the bridge deck steel plate by the cooperation of bolts and holes. The asphalt road surface is built on the steel plates of the bridge deck for vehicles to travel on.

2. The prefabricated bridge spanning a deep, water-filled karst cave as described in claim 1, characterized in that, The bridge deck steel plate is composed of a number of small steel plates, each of which is rectangular in structure. The long side of each small steel plate is equal to the width of the bridge. All the small steel plates are spliced ​​together along the length of the bridge to form the entire bridge deck steel plate.

3. The prefabricated bridge spanning a deep, water-filled karst cave as described in claim 1, characterized in that, The working principle of the bridge is as follows: Inclined beams and upper longitudinal beams bear the entire load of the bridge. The inclined beams are obliquely anchored in the rock strata on both sides of a deep, water-filled karst cave. The two inclined beams share a common end point, forming a triangular skeleton, which is the largest load-bearing component and mainly bears downward pressure. Under the bridge load, the inclined beams are pressed into the mountain without damaging the mountain's structure, increasing the stability of the bridge support. Simultaneously, the left and right inclined beams and the lower longitudinal beam at the bottom form a large triangle. Several inclined bars are installed in the opposite direction to the corresponding inclined beams, forming small triangles between the inclined bars and vertical bars, and between the inclined bars and the inclined beams, and between the inclined bars and the lower longitudinal beams. The combined use of large, medium, and small triangles increases the overall stability and load-bearing capacity.

4. The prefabricated bridge spanning a deep, water-filled karst cave according to claim 1, characterized in that, The bridge is equipped with multiple nodes, including a first node, a second node, a third node, a fourth node, a fifth node, a sixth node, and a seventh node; The first and second nodes are used to connect the lower longitudinal beam, the lower vertical bar, the diagonal bar and the horizontal beam. The connection ends of the diagonal bar, the lower vertical bar and the horizontal beam to the lower longitudinal beam are all welded with steel plates. The steel plates are provided with round holes. The lower longitudinal beam is made of U-shaped steel. The bottom surface of the U-shaped steel is provided with round holes along the length direction that correspond to the positions of the round holes on the steel plate. The connection is achieved by using bolts passing through the round holes on the steel plate and the round holes on the bottom surface of the U-shaped steel. The second node is connected to only one diagonal bar, while the first node is connected to two diagonal bars. The two diagonal bars are symmetrically arranged with the longest lower vertical bar as the center. Bolt holes are provided on the side of the lower longitudinal beam U-shaped steel for connecting it to the adjacent lower cross beam by bolts. The third node is used to connect the lower longitudinal beam, the lower vertical rod, and the lower horizontal beam. The connection end of the lower vertical rod and the lower longitudinal beam is welded with a steel plate. The steel plate has at least two round holes. The bottom surface of the U-shaped steel of the lower longitudinal beam has round holes corresponding to those of the steel plate. The connection is achieved by bolts passing through the round holes of the steel plate and the round holes of the U-shaped steel. The side of the U-shaped steel of the lower longitudinal beam is provided with bolt holes for connecting it to the adjacent lower horizontal beam by bolts. The fourth node is connected to the lower longitudinal beam, the inclined beam and the lower transverse beam through the first connector. The lower longitudinal beam, the lower transverse beam and the connection end of the first connector are welded with steel plates. The steel plates are provided with round holes. The first connector is provided with screw holes corresponding to the round holes of the steel plates. The connection is achieved by using bolts passing through the round holes of the steel plates and the screw holes of the first connector. The fifth node is connected to the upper longitudinal beam, the longest lower vertical rod, and the inclined beam through the second connector. The connection end of the longest lower vertical rod and the second connector is welded with a steel plate. The steel plates at the connection ends of the upper longitudinal beam and the longest lower vertical rod are provided with round holes. The second connector is provided with screw holes corresponding to the round holes on the upper longitudinal beam and the steel plate. The connection is achieved by using bolts passing through the round holes and the corresponding screw holes on the second connector. The first connector is an irregular structure, with a cuboid shape and an inclined through hole inside, used to connect the inclined beam, the lower longitudinal beam and the lower cross beam, or to connect the inclined beam, the upper and lower vertical bars, the inclined bar and the cross beam; The second connector is an irregular structure, divided into left and right parts. The second connector is a symmetrical structure, and both left and right parts are hollow steel components with oblique circular holes of a size that matches the diameter of the oblique beam. The sixth node is used to connect the upper longitudinal beam, the upper vertical rod and the upper horizontal beam. The upper vertical rod and the upper horizontal beam are connected to the upper longitudinal beam by welding steel plates. The steel plates have round holes. The bottom and side surfaces of the upper longitudinal beam U-shaped steel have round holes corresponding to the steel plates. The connection is achieved by using bolts passing through the round holes of the steel plates and the round holes of the U-shaped steel. The seventh node is connected to the inclined beam, inclined rod, upper vertical rod, lower vertical rod and middle horizontal beam through the first connector. The connection ends of the upper and lower vertical rods, inclined rods and middle horizontal beam to the first connector are all welded with steel plates.

5. The prefabricated bridge spanning a deep, water-filled karst cave according to claim 4, characterized in that, The first connector is divided into upper and lower parts and is fixed to the inclined beam by bolts. When the upper and lower parts of the first connector are put together, an inclined through hole for installing the inclined beam can be formed in the middle. The top surface of the upper part is provided with two screw holes, and the left and right sides are provided with screw holes for fixing to the lower or middle crossbeam. An extension is provided at the bottom of the left and right sides. The front surface of the lower part is provided with two rows of symmetrically arranged screw holes for fixing to the steel plate at the end of the U-shaped steel of the lower longitudinal beam. Each row of screw holes has two screw holes. The two rows of screw holes are distributed near the edge of the front surface of the lower part. The bottom of the lower part is also provided with two screw holes. When the first connector is used at the fourth node, the two screw holes on the top and bottom surfaces of the upper and lower parts are idle. When the first connector is used at the seventh node, the two screw holes on the top and bottom surfaces of the upper and lower parts are used to connect the upper and lower vertical bars respectively. An extension is also provided at the upper end of the left and right sides of the lower part. After the upper and lower parts are covered by each other, they are connected into a whole by bolts through the corresponding screw holes on the extension and the steel pipe is wrapped and fixed.

6. The prefabricated bridge spanning a deep, water-filled karst cave according to claim 4, characterized in that, A number of vertical screw holes are provided on the top surface of the second connector for fixing to the upper longitudinal beam, and a number of vertical screw holes are provided on the bottom surface for fixing to the steel plate on the longest lower vertical rod; multiple sets of horizontal screw holes are arranged on the second connector at the positions above and below the oblique circular hole, and the horizontal screw holes are used to connect the left and right oblique beams into one piece by bolts; two sets of transverse screw holes are symmetrically arranged on the left and right sides of the upper center of the second connector, and the transverse screw holes are used to connect the oblique beam to the upper cross beam into one piece by bolts. The left and right parts of the second connector are inserted into the two oblique beams, and then the left and right parts are fixed to fix the left and right oblique beams.

7. The prefabricated bridge spanning a deep, water-filled karst cave according to claim 6, characterized in that, The thickness of the second connector, which fits into the left and right parts of the inclined beam, is 10-20cm.

8. The prefabricated bridge spanning a deep, water-filled karst cave according to any one of claims 1-7, characterized in that, The large karst caves mentioned refer to those with a width exceeding 20m and a height exceeding 10m, and the bridge spans are 20m-50m; all components of the bridges are made of prefabricated materials to achieve the purpose of rapid assembly construction.

9. A construction method for a prefabricated bridge spanning a deep, water-filled karst cave as described in claim 1, characterized in that, The construction method includes the following steps: Step 1: First, determine the length and width of the bridge based on the road grade, road surface width and height, and the size of the karst cave. Then, design the materials and dimensions of each component of the prefabricated bridge. Step 2: Measure and lay out the anchoring position of the inclined beam, then drill holes in the cave wall, clean the debris in the holes, insert the steel pipe concrete inclined beam into the drill holes, connect the other ends of the left and right inclined beams with bolts in the middle of the span, and finally pour micro-expansion cement grout into the drill holes to fix the inclined beams. Step 3: Measure and lay out the anchoring position of the upper longitudinal beam, then drill holes in the cave wall, clean the debris in the holes, insert the U-shaped steel upper longitudinal beam into the holes, and finally pour micro-expansion cement grout into the holes to fix the upper longitudinal beam. Step 4: Install the lower longitudinal beam and connect it to the diagonal beam; Step 5: Install the upper and lower vertical bars, and connect the upper and lower vertical bars of different lengths to the upper longitudinal beam, lower longitudinal beam, and diagonal beam; Step 6: Install the diagonal bracing, connecting it to the lower longitudinal beam, diagonal beam, and vertical bracing; Step 7: The diagonal beams, longitudinal beams, vertical bars and diagonal bars are combined to form a truss. Multiple trusses are arranged horizontally, and crossbeams are installed. The different horizontal trusses are connected by the upper, middle and lower crossbeams. Step 8: Install the bridge deck steel plates and connect them to the upper longitudinal beams and upper transverse beams using bolts; Step 9: Lay the asphalt pavement of the bridge deck in layers to complete the construction of the prefabricated bridge.

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