TECHNICAL FIELD
The present invention belongs to the strategic emerging industries such as intelligent manufacturing equipment, satellites and application industries, which belongs to intelligent monitoring and controlling system devices including satellite navigation intelligent monitoring signal reception and processing system, intelligent control cable, and intelligent tension control system in the field of bridge construction technology. Specifically, it relates to a rapid and safe construction and intelligent monitoring and controlling method for the double-span or multi-span continuous arch bridges.
BACKGROUND
Transportation is a key to developing a country and the foundation of strengthening a nation. With the deepening implementation of the national strategy of building a strong transportation network, an increasing number of large-span bridges are being constructed. Specially, when it is necessary to cross adjacent double valleys or multiple valleys, or when it is necessary to connect three or more adjacent islands, double-span or multi-span continuous arch bridges are one of the most competitive types of large-span bridges.
The cable-stayed hanging construction method of arch bridges proposed by Jielian Zheng has become a common construction method for large-span arch bridges. The cable crane system can hoist the arch rib segments to the installation position, and the cable-stayed hanging system is a critical construction technology that ensures the accuracy of arch rib line shape and the closure accuracy of arch rib. For the installation of arch rib segments using cable-stayed hanging method for single-span arch bridges, the technology is relatively mature, and the construction sequence is generally summarized as follows: (1) installing a part of segments of one side arch rib using cable-stayed hanging method; (2) moving the cable crane system horizontally; (3) installing a part of segments of the other side arch rib; (4) install the transverse brace; (5) continue installing the arch rib segments; (6) repeating the steps (2), (3), and (4) until the installation of the arch ribs are completed.
For the construction of double-span or multi-span continuous arch bridges, taking a double-span continuous arch bridges as an example, when installing arch rib segments on the middle pier and its overhead anchorage tower, due to the sequential installation of arch rib segments, there are asymmetrical and unbalanced conditions between the arch rib segments on the left side and right side of the middle pier, which has adverse loading effect on the middle pier and its overhead anchorage tower. Currently, the technology of installing arch rib segment with cable-stayed hanging method is not widely used in double-span or multi-span continuous arch bridges, and now the research is still immature. Taking a double-span continuous arch bridge as an example, the simultaneous construction method of the left half and right half arch ribs of the double-span (4 arch ribs in total) are introduced as follows. FIG. 1 is a construction illustration of hanging arch rib on the middle pier (taking the stage on arch rib segment {circle around (3)} as an example). The construction sequence is generally written as follows: (1) installing the cable system at the corresponding position on the transverse-left arch rib (assuming that the transverse-left arch rib is constructed first); (2) using the cable crane system to lift the segment {circle around (3)} of the transverse-left arch rib to the corresponding position on the right side of the middle pier; (3) the arch rib segment {circle around (3)} on the right side of the middle pier is temporarily connected with the previously installed rib segment {circle around (2)} by an inner flange, and then, the normal cable (connecting the arch rib segment and the ground) is used on the left side of the middle pier to balance the self-weight of the right side arch rib, ensuring that the middle pier is in a vertical and balanced state; (4) arch rib segment {circle around (3)} on the left side of the middle pier is craned to the target position, and the tension cable between the arch rib and the ground is loosened simultaneously when the joint is connected with the inner flange; (5) simultaneously extending the clasp cables of segment {circle around (3)} for both left and right arch rib of the middle pier, to maintain the balance of middle pier; (6) installing the transverse-left arch rib segments in this sequence; (7) moving the cable crane system horizontally to the position of the transverse-right arch rib; (8) installing the segments of the transverse-right arch rib in the same way; (9) moving the cable crane system horizontally to the position of the transverse brace, and then installing the transverse brace; (10) repeating the above steps, and gradually hanging the arch rib segments, until the installation of the arch rib on middle pier is completed.
The existing construction methods for double-span continuous arch bridge mentioned above have following problems:
- (1) The new arch rib segment is temporarily connected with an inner flange, which is in a cantilever state, and the flange is subjected to excessive loading, and maybe resulting in failure and potential safety problems.
- (2) After the new arch rib segment is connected in the target location, the clasp cable of the arch rib segment has not been extended, and the dead weight of the new arch rib segment would lead to a significant increase in the tension force for the clasp cable on the previous arch rib segment. Therefore, the demand for the cross-sectional area of the clasp cable is large, and the amount of the clasp cable usage is large, and there is a waste of the clasp cable.
- (3) The normal tension cables for each segment installation require changing the anchor point position, which results in a complex procedure and increases the construction period.
- (4) Four arch ribs are constructed simultaneously, the cable crane system has to move horizontally many times, and it requires moving the cable crane system every time when installing to the position of the transverse brace. This results in increased construction difficulty and prolonged construction period.
To address the above technical problems, the present invention discloses a method for rapid and safe construction and intelligent monitoring and controlling of continuous arch bridges, which could reduce the amount of clasp cable usage, greatly improve work efficiency, significantly shorten the construction period. It has significant practical value for the rapid and safe construction of double-span or multi-span continuous arch bridges.
SUMMARY OF THE INVENTION
The present invention proposes a method for rapid and safe construction and intelligent monitoring and controlling of continuous arch bridges, which is applicable to double-span and multi-span continuous arch bridges with using a single-arch rib construction method. Take a double-span continuous arch bridge as an example, the arch rib 1 includes four sub-arch ribs, namely, the longitudinal-left span transverse-left arch rib 101, the longitudinal-left span transverse-right arch rib 102, the longitudinal-right span transverse-left arch rib 103, the longitudinal-right span transverse-right arch rib 104, and one of the sub-arch rib could be divided into several rib segments. The middle pier 2 is a bridge pier located on the middle of the two arch ribs 1, while side piers 3 are two bridge piers located on the sides of the two arch ribs 1. The cable crane system 4 can hoist the arch rib segments to the installation position, and mainly includes the cable tower 401 and the load-bear cable 402. The cable tower 401 could be installed on the side pier 3, or alternatively, it could be installed separately if needed (as shown in the right cable tower 401 in FIG. 2). The cable crane system 4 is operated using normal methods in the construction method of present invention, and would not be further described. The cable-stayed hanging system 5 is a critical construction subsystem that ensures the accuracy of arch rib line shape and closure accuracy of arch rib, mainly including the clasp cable 501, the lower anchor point 502 of the clasp cable, the upper anchor point 503 of the clasp cable, and the anchorage tower 504. The anchorage tower 504 is usually set on the top of the middle pier 2 or the side pier 3, and the lower anchor point 502 of the clasp cable is set on the arch rib segment, and a part of the upper anchor point 503 of the clasp cable is set on the middle pier 2 or the side pier 3, while the other part is set on the anchorage tower 504.
For the construction of a continuous arch bridge, when the middle pier 2 and its overhead anchorage tower 504 are used to hang and connect the arch rib segments, due to the sequence of segments installation, there is asymmetry and unbalanced working conditions on the left side and right side of the middle pier 2, which has adverse loading effect on the middle pier 2 and its overhead anchorage tower 504. Furthermore, the construction process of simultaneous construction of two arch ribs results in a slower construction speed. To address these two issues, the present invention proposes a rapid and safe construction and intelligent monitoring and controlling method for continuous arch bridges. The construction method of the invention is safe and simple, which could effectively shorten the construction period and save costs, and has great application value, good economic and social benefits.
The technical solution of the present invention is exhibited as follows:
A method for rapid and safe construction and intelligent monitoring and controlling of continuous arch bridges, suitable for double-span and multi-span continuous arch bridges. For double-span continuous arch bridges, the method first installs the two transverse-left arch rib, including longitudinal-left span transverse-left arch rib 101 and the longitudinal-right span transverse-left arch rib 103, using the cable-stayed hanging method, until all the segments of the longitudinal-left span transverse-left arch rib 101 and the longitudinal-right span transverse-left arch rib 103 are installed and completed closure. After completing closure, removing the clasp cables 501, and then switching to a single-arch rib closure state. Subsequently, the cable crane system 4 excluding the cable tower 401 is horizontally moved to the transverse-right arch rib position, and the clasp cables 501 removed from the transverse-left arch rib are reused to hang and install the the longitudinal-left span transverse-right arch rib 102 and the longitudinal-right span transverse-right arch rib 104, until all segments of the transverse-right arch rib are hung and installed, and then removing the clasp cables 501 after completing closure. Subsequently, the cable crane system 4 excluding cable tower 401 is moved horizontally to the position of the transverse brace 7, and the transverse brace 7 is lifted and installed, which can connect the left and right arch ribs together, and then switching to a double-arch rib whole subjected state. Finally, the subsequent procedures after the closure of the two arch ribs are finished, then the construction of the arch bridge is completed.
After the arch rib is connected in the target position, the corresponding cable 501 is extended, and the imbalance loading of the middle pier 2 and and its overhead anchorage tower 504 is balanced through the intelligent control cable 6. The ground anchor of the intelligent control cable 6 is anchored on the foundation of the side pier 3. Wherein, the intelligent control cable 6 is a normal steel stranded wire or fiber FRP composite intelligent cable. The cable tension force of intelligent control cable 6 is solved through a mechanical analysis method, or the value of cable tension force is determined by ensuring that the top of anchorage tower 504 is in zero horizontal displacement. An intelligent monitoring signal receiving and processing system based on satellite navigation or image processing is installed at the top of the anchorage tower 504, in order to monitor the horizontal displacement at the top of the anchorage tower 504 in real time. The displacement is input into the tension control system installed at the lower end of the intelligent control cable 6, when the top displacement of the anchorage tower 504 exceeds the target threshold, the tension force of the intelligent control cable 6 is adjusted, to restore the top displacement of the anchorage tower 504 to 0 or within the range of target threshold, ensuring that the middle pier 2 and its overhead anchorage tower 504 is in a vertical and balanced state at all times. The arch rib segments are numbered starting from the arch foot to the arch crown, and the arch rib segment at the arch foot is the segment 1, and the arch rib segment at the arch crown is the segment z. The segment 1 to segment x do not require the intelligent control cable 6 at the unbalanced state, and its unbalanced loading is borne by itself stiffness of the middle pier 2. The value of x needs to be determined based on the calculation with finite element model analysis software, with the control criterion being that there are no tensile stresses at the bottom of middle pier 2 and the maximum horizontal displacement at the top of the anchorage tower 504 meets the requirements for construction safety. The upper anchor points 503 of the clasp cables for the segment (x+1) to segment y are anchored in the concrete of the middle pier 2, and the anchor points of the intelligent control cable 6 on the middle pier 2 are all set at the top of the middle pier 2 correspondingly. The anchor points of the clasp cables for the arch rib segment (y+1) to the arch rib segment z are set on the anchorage tower 504 of the middle pier 2, and the anchor points of the intelligent control cable 6 on the anchorage tower 504 are set at the corresponding vertical positions of the clasp cables on the anchorage tower. The arch rib segments are installed in sequence, and when at an unbalanced state, the intelligent control cable 6 is adjusted to the required intelligent control tension force, keeping the middle pier 2 in a vertical balanced state.
The specific construction steps are as summarized follows:
- Step 1: (FIG. 7) Casting side pier 3, installing cable crane system 4, and then using the cable crane system 4 to cast middle pier 2.
- Step 2: (FIG. 8) Installing the longitudinal-left span transverse-left arch rib 101 and the longitudinal-right span transverse-left arch rib 103. The cable crane system 4 is located in the position of transverse-left arch rib. Installing the segment 1 to segment x transverse-left arch rib segments in sequence. After the segment on the side pier 3 is connected in the target position, extending the clasp cable and back clasp cable immediately, and then the clasp cable is extended immediately after the segment on the middle pier 2 is connected in the target position. The arch rib segment 1 to arch rib segment x do not require installing the intelligent control cable 6, relying on the stiffness of the middle pier 2 to resist unbalanced loading, until the installation of the arch rib segment 1 to arch rib segment x of the two transverse-left arch rib segments are completed.
- Step 3: (FIG. 9) Installing the arch rib segment (x+1) on the two side piers 3, placing the arch rib segment (x+1) on the right side of the middle pier, and then installing the intelligent control cable 6. The lower anchor point of the intelligent control cable 6 is set on the foundation of side pier 3, and the upper anchor point is set on the top of middle pier 2. When extending clasp cable 501 of the arch rib segment (x+1) on the right side, the intelligent control cable 6 simultaneously applies intelligent control cable force, keeping middle pier 2 always in a vertical and balanced state.
- Step 4: (FIG. 10) Placing the arch rib segment (x+1) on the left side of the middle pier 2, when extending clasp cable 501 of the arch rib segment (x+1) on the left side, the intelligent control cable 6 releases its intelligent control cable force synchronously, keeping the middle pier 2 in a vertical and balanced state, and the intelligent control cable 6 does not need to be removed.
- Step 5: (FIG. 11) Following the methods in steps 3 and 4, completing the installation of the arch rib segment (x+1) to the arch rib segment y.
- Step 6: (FIG. 12) Installing the anchorage tower 504, moving the upper anchor point of the intelligent control cable 6 to the top of anchorage tower 504 or the corresponding vertical position of the clasp cable 501 of segment (y+1) on the right side of the anchorage tower 504 of the middle pier. Then, installing segment (y+1) on the two side piers, and then placing the segment (y+1) on the right side of the middle pier. When extending clasp cable 501 of the arch rib segment (y+1) on the right side, the intelligent control cable 6 simultaneously applies the intelligent control tension force, maintaining the middle pier 2 always in a vertical and balanced state.
- Step 7: (FIG. 13) Placing the arch rib segment (y+1) on the left side of the middle pier 2, when extending clasp cable 501 of the arch rib segment (y+1) on the left side, the intelligent control cable 6 synchronously releases the intelligent control tension force, so that the middle pier 2 always maintains a vertical and balanced state. Specially, the intelligent control cable 6 does not need to be removed.
- Step 8: (FIG. 14) Following the methods described in steps 6 and 7, and then completing the installation of the arch rib segment (y+1) to arch rib segment z.
- Step 9: (FIG. 15) The longitudinal-left span transverse-left arch rib 101 and the longitudinal-right span transverse-left arch rib 103 are completed closure, the clasp cables 501 are symmetrically removed, and then switching to a single-arch rib closure state.
- Step 10: (FIG. 16) Moving the cable crane system 4 excluding the cable tower 401 to the transverse-right arch rib position. Completing the installation of the longitudinal-left span transverse-right arch rib 102 and the longitudinal-right span transverse-right arch rib 104 on the transverse-right arch rib following the above mentioned steps, then completing closure and symmetrically and orderly removing the clasp cables 501. Moving the cable crane system 4 excluding the cable tower 401 to the transverse brace position, lifting and installing the transverse brace, and then switching to a double-arch rib whole subjected state.
- Step 11: (FIG. 17) The subsequent construction procedures after the closure of the two arch ribs are finished, then the construction of the arch bridge is completed.
The beneficial effects of the present invention: the single-arch rib construction method proposed by the present invention is especially suitable for the deck concrete-filled steel tube arch bridges or deck steel arch bridges. Deck arch bridges often have a large arch rib width in order to improve the out-of-plane stability of the arch rib due to the advantage that the width of the arch rib does not occupy the width of the bridge deck. Therefore, the single-arch rib construction method for deck arch bridges could meet the safety requirements of construction without obvious limited factors. Take a double-span continuous deck concrete-filled steel tube arch bridge with a single span of 400 m as an example (refer to FIG. 2), its arch rib width is 7.5 m, and the stability coefficient at the single-arch rib closure state is 6, which meets the safety requirement of not less than 4 according the code. Meanwhile, The single-arch rib construction method proposed in present invention is also applicable to though and half-through arch bridges with a limited span. The arch ribs of the through and half-through arch bridges occupy the width of the bridge deck, and the arch rib width should not be too wide generally, and generally not exceeding 4.5 m. The out-of-plane stiffness of single-arch rib decreases with an increase of the span of the arch bridge, which is prone to out-of-plane instability and could not ensure the construction safety. Therefore, the applicability of single-arch rib construction method to through and half-through arch bridges needs to be determined by stability calculation. According to the Specification for Design of Highway Concrete-Filled Steel Tubular Arch Bridges (JTG-T D65-06-2015, (in Chinese)), for through and half-through arch bridges, when the stability coefficient at the single-arch rib closure state is larger than 4, the single-arch rib construction method could be used for construction. Further stability analyses at the single-arch rib closure state for through and half-through arch bridges were carried out using finite element modeling. For a half-through arch bridge with a span of 150 m and a rib width of 2.2 m, its stability coefficient at the single-arch rib closure state was 12.7, indicating that the single-arch rib construction method could be adopted. For a half-through arch bridge with a span of 228 m and a rib width of 2.4 m, its stability coefficient was 4.7, also indicating the construction suitability of the single-arch rib construction method. However, for the Pingnan Sanqiao bridge with a span of 575 m and a rib width of 4.2 m, its stability coefficient was only 0.8, indicating the single-arch rib construction method is infeasible. Therefore, for through and half-through arch bridges, taking concrete-filled steel tube bridges as an example, to ensure the stability of the arch ribs during construction, the single-rib construction method is generally recommended for through and half-through concrete-filled steel tube bridges with a span not exceeding 250 m.
(1) The present invention proposes a single-arch rib construction method, in which the number of lateral movement of the cable crane system is reduced to 1/n of the normal method, and n is the number of segments of the half-span of one arch rib. This method reduces the construction difficulty, significantly improves the work efficiency, shortens the construction period and reduces costs.
(2) The present invention proposes a single-rib arch construction method, in which the clasp cables could be reused to the installation of the other arch rib, resulting in a half of reduction on the clasp cable usage. Furthermore, when installing a new segment, the clasp cable is immediately extended, and then using an intelligent control cable to ensure that the pier and anchorage tower are in a balanced state. The newly installed segment is no longer in a cantilever state, and the loading on the flange is very small, resulting in a small change in the tension force for the clasp cables of the previous segments, which also saves the amount of clasp cable usage. The combination of these two points could save more than half of the clasp cable usage.
(3) The cable-stayed hanging construction method in the present invention adopts a construction optimization calculation approach for calculating, which could achieve minimal changes of the cable tension force, and effectively control the uniformity of cable tension force during the construction process, thereby improving the assembly accuracy of the arch rib line shape on the cable-stayed hanging construction.
(4) The present invention proposes a construction method that uses intelligent control cable to balance the unbalanced loading on the middle pier. The intelligent control cable tension force could be determined through mechanical analysis or controlled by ensuring the top of the anchorage tower is in zero horizontal displacement. The dual control of force and displacement effectively ensures the accuracy and safety of the installation for the arch rib hanging on the middle pier. The present invention proposes a construction method that uses intelligent control cable to balance the unbalanced loading on the middle pier, and the ground anchor of the intelligent control cable is generally fixed on the foundation of side pier, and the anchorage position does not need to be changed after being fixed. The present construction method is more convenient and suitable for deep canyon terrain, which could effectively shorten the construction period and save costs.
(5) The present invention proposes a construction method that uses an intelligent control cable to balance the unbalanced loading on the middle pier, and generally does not require the use of an intelligent control cable for the first few segments, as the unbalanced loading is borne by itself stiffness of the middle pier. For the middle segments, the anchor points of the clasp cables are usually anchored in the concrete of the bridge pier, and the anchor point of the intelligent control cable on the middle pier could be set at the top of the bridge pier. For the last few segments, the anchor point of the clasp cable is generally set on the anchorage tower of the middle pier, and the anchor point of the intelligent control cable on the anchorage tower of the middle pier is set at the corresponding vertical position of the clasp cable. Therefore, the intelligent control cable has fewer changes in anchor point positions on the middle pier. Compared with the normal method of frequently changing the anchor point of the cables on the arch rib to balance the loading, the construction method proposed in present invention is simpler and could effectively shorten the construction period.
(6) The construction method proposed in present invention, which uses intelligent control cables to balance the unbalance loading on the middle pier, could be applied to the construction of continuous arch bridges spanning rivers and seas. Meanwhile, the construction method proposed in present invention could also be used on the construction of single-span arch bridges, showing great potential for application and promotion with significant economic and social benefits.
DRAWINGS
FIG. 1 is a schematic diagram of the normal cable-stayed hanging construction method on the middle pier of a continuous arch bridge.
FIG. 2 is a schematic diagram of an overall construction method for a continuous arch bridge.
FIG. 3 is a schematic diagram of the cable-stayed hanging construction on the middle pier.
FIG. 4 is a construction schematic diagram at the unbalanced state of the segment {circle around (3)} on the middle pier.
FIG. 5 is a construction schematic diagram at the unbalanced state of the segment {circle around (6)} on the middle pier.
FIG. 6 is a construction schematic diagram at the unbalanced state of the segment {circle around (9)} on the middle pier.
FIG. 7 is a construction schematic diagram at step 1.
FIG. 8 is a construction schematic diagram at step 2 (imbalanced state of segment {circle around (3)}.
FIG. 9 is a construction schematic diagram at step 3 (imbalanced state of segment {circle around (4)}).
FIG. 10 is a construction schematic diagram at step 4 (balanced state of segment {circle around (4)}).
FIG. 11 is a construction schematic diagram at step 5 (balanced state of segment {circle around (6)}).
FIG. 12 is a construction schematic diagram at step 6 (imbalanced state of segment {circle around (7)}).
FIG. 13 is a construction schematic diagram at step 7 (balanced state of segment {circle around (7)}).
FIG. 14 is a construction schematic diagram at step 8 (balanced state of segment {circle around (9)}).
FIG. 15 is a construction schematic diagram at step 9 (single-arch rib closure state).
FIG. 16 is a construction schematic diagram at step 10 (double-arch rib whole subjected state).
FIG. 17 is construction schematic diagram at step 11 (bridge completed state).
Where in the figure: 1 arch rib; 101 longitudinal-left span transverse-left arch rib; 102 longitudinal-left span transverse-right arch rib; 103 longitudinal-right span transverse-left arch rib; 104 longitudinal-right span transverse-right arch rib; 1˜9 arch rib segments; 2 middle pier; 3 side pier; 4 cable crane system; 401 cable tower; 402 load-bearing cable; 5 cable-stayed hanging system; 501 clasp cable; 502 lower anchor point; 503 upper anchor point; 504 anchorage tower; 6 intelligent control cable; 7 transverse brace.
DETAILED DESCRIPTION
Based on FIGS. (2-17), a further detailed description of the construction technology scheme is provided with a typical double-span continuous deck concrete-filled steel tube arch bridge crossing a double valleys.
A method for rapid and safe construction and intelligent monitoring and controlling of continuous arch bridges, taking a double-span continuous arch bridge as an example, as shown in FIG. 2, it includes arch rib 1, middle pier 2, side pier 3, cable crane system 4 (cable tower 401, load-bearing 402), cable-stayed hanging system 5 and intelligent control cable 6.
As shown in FIG. 2, the arch rib 1 includes four sub-arch ribs, namely, the longitudinal-left span transverse-left arch rib 101, the longitudinal-left span transverse-right arch rib 102, the longitudinal-right span transverse-left arch rib 103, the longitudinal-right span transverse-right arch rib 104, and one of the sub-ribs could be divided into several arch rib segments. The example bridge in FIG. 2 divides one sub-arch rib into 9 arch rib segments, labeled as segment {circle around (1)} to segment {circle around (9)}. As shown in FIG. 2, the middle pier 2 is a bridge pier located on the middle of the two arch ribs 1, while side piers 3 are two bridge piers located on the sides of the two arch ribs 1.
The cable crane system 4 can hoist the arch rib segments to the installation position, and mainly includes the cable tower 401 and the load-bear cable 402. The cable tower 401 could be installed on the side pier 3, or alternatively, it could be installed separately if needed (as shown in the right cable tower 401 in FIG. 2). The cable crane system 4 is operated using normal methods in the construction method of the present invention, and would not be further described.
As shown in FIG. 2 and FIG. 3, the cable-stayed hanging system 5 is a critical construction subsystem that ensures the accuracy of arch rib line shape and the closure accuracy of arch rib, mainly including the clasp cable 501, the lower anchor point 502 of the clasp cable, the upper anchor point 503 of the clasp cable, and the anchorage tower 504. The anchorage tower 504 is usually set on the top of the middle pier 2 or the side pier 3, the lower anchor point 502 of the clasp cable is installed on the rib segment, and a part of the upper anchor point 503 of the clasp cable is set on the middle pier 2 or the side pier 3, while the other part is set on the anchorage tower 504.
As shown in FIG. 2, the intelligent control cable 6 is applied to balance the unbalanced loading on the middle pier 2 and its anchorage tower 504 when installing the arch rib segments. The intelligent control cable is a normal steel stranded wire or fiber FRP composite intelligent cable.
The present invention discloses a rapid and safe construction and intelligent monitoring and controlling method, with using a single-arch rib construction approach. The method first installs the two transverse-left arch rib, including longitudinal-left span transverse-left arch rib 101 and the longitudinal-right span transverse-left arch rib 103, using the cable-stayed hanging method, until all the segments of the longitudinal-left span transverse-left arch rib 101 and the longitudinal-right span transverse-left arch rib 103 are installed and completed closure. After completing closure, removing the clasp cables 501, and then switching to a single-arch rib closure state. Subsequently, the cable crane system 4 excluding the cable tower 401 is horizontally moved to the transverse-right arch rib position, and the clasp cables 501 removed from the transverse-left arch rib are reused to hang and install the the longitudinal-left span transverse-right arch rib 102 and the longitudinal-right span transverse-right arch rib 104, until all segments of the transverse-right arch rib are hung and installed, and then removing the clasp cables 501 after completing closure. Subsequently, the cable crane system 4 excluding cable tower 401 is moved horizontally to the position of transverse brace 7, and then the transverse brace 7 is lifted and installed, which can connect the left and right arch ribs together, and then switching to a double-arch rib whole subjected state. Finally, the subsequent procedures after the closure of the two arch ribs are finished, then the construction of the arch bridge is completed.
The present invention discloses a rapid and safe construction and intelligent monitoring and controlling method, with using a single-arch rib construction approach, in which the clasp cables 501 could be reused on the installation of the other arch rib, resulting in a half of reduction on the clasp cable 501 usage. Furthermore, when installing a new segment, the clasp cable is immediately extended, and then using an intelligent control cable to ensure that the pier and anchorage tower are in a balanced state. The newly installed segment is no longer in a cantilever state, and the loading on the flange is very small, resulting in a small change in the tension force for the clasp cables of the previous segments, which also saves the amount of clasp cable usage. The combination of these two points could save more than half of the clasp cable usage.
The present invention discloses a rapid and safe construction and intelligent monitoring and controlling method, with using a single-arch rib construction approach, in which the number of lateral movement of the cable crane system is reduced to 1/n of the normal method, and n is the number of segments of the half-span of one arch rib. This method reduces the construction difficulty, significantly improves the work efficiency, shortens the construction period and reduces costs.
For the construction of a double-span arch bridge, when the middle pier 2 and its overhead anchorage tower 504 are utilized to hang and connect the arch rib segments, due to the sequence of segments installation, there is asymmetry and unbalanced working conditions on the left side and right side of the middle pier 2, which has adverse loading effect on the middle pier 2 and its overhead anchorage tower 504. To address these issue, the present invention proposes a construction method that utilizes the intelligent control cable to balance the imbalanced loading on the middle pier and its upper tower.
As shown in FIG. 2, the ground anchor of the intelligent control cable in present invention is generally fixed on the foundation of side pier, and the anchorage position does not need to be changed after being fixed. After the arch rib segment is connected in the target position, the corresponding cable 501 is extended, and the imbalance loading on the middle pier 2 and its overhead anchorage tower 504 is balanced through the intelligent control cable 6. The cable tension force of intelligent control cable 6 is solved through a mechanical analysis method, or the value of cable tension force is determined by ensuring that the top of anchorage tower 504 is in zero horizontal displacement. The dual control of force and displacement effectively ensures the accuracy and safety of the installation of the arch rib hanging on the middle pier. Hence, an intelligent monitoring signal receiving and processing system based on satellite navigation or image processing is installed at the top of the anchorage tower 504, in order to monitor the horizontal displacement at the top of the anchorage tower 504 in real time. The displacement is automatically input into the tension control system installed on the intelligent control cable 6, when the top displacement of the anchorage tower 504 exceeds the target threshold, the tension force of the intelligent control cable 6 is adjusted, to restore the displacement of the anchorage tower 504 to 0 or within the range of target threshold, ensuring that the middle pier 2 and its overhead anchorage tower 504 is in a vertical and balanced state at all times.
Taking the double-span continuous arch bridge as an example (refer to FIG. 2), the maximum required tension forces of the intelligent control cables do not exceed 300 tons at the unbalanced state of each segment. The intelligent control cable could use normal steel stranded wire or fiber FRP composite intelligent cable.
Taking a double-span continuous arch bridge as an example (refer to FIG. 2), as shown in FIG. 4, the present invention proposes a construction method that utilizes intelligent control cable to balance the imbalanced loading on the middle pier and its upper tower. For the first three arch rib segments at the unbalanced state, the angles between the clasp cables 501 and the middle pier 2 are small, and the distances between the upper anchor points 503 of the clasp cables and the bottom of the middle pier 2 are also relatively small, resulting in a short arm for the unbalanced loading, thus the middle pier 2 is subjected to a relatively small unbalanced loading. Hence, the segment {circle around (1)} to segment {circle around (3)} do not require the intelligent control cable 6 at the unbalanced state, and its unbalanced loading is borne by itself stiffness of the middle pier 2. Based on the calculation with finite element model analysis software, it is found that no tensile stress appears at the bottom of the middle pier 2 when the intelligent control cable 6 is not utilized for arch rib segment {circle around (3)} at the unbalanced state, and the maximum horizontal displacement at the top of the middle pier 2 satisfies the safety requirements of the construction.
Taking the double-span continuous arch bridge as an example (refer to FIG. 2), as shown in FIG. 5, the upper anchor points 503 of the clasp cables for the segment {circle around (4)} to segment {circle around (6)} are anchored in the concrete of the middle pier 2, and the anchor points of the intelligent control cable 6 on the middle pier 2 are all set at the top of the middle pier 2 correspondingly. As shown in FIG. 6, the anchor points of the clasp cables for the arch rib segment {circle around (7)} to the arch rib segment {circle around (9)} are set on the anchorage tower 504 of the middle pier 2, and the anchor points of the intelligent control cable 6 on the anchorage tower 504 are set at the corresponding vertical positions of clasp cables on the anchorage tower.
The arch rib segments are installed in sequence, and when at an unbalanced state, the intelligent control cable 6 is adjusted to the required intelligent control tension force, keeping the middle pier 2 in a vertical and balanced state. Compared with the normal method of frequently changing the anchor point of the cables on the arch rib to balance the loading, the intelligent control cable construction method proposed in present invention is simpler and could effectively shorten the construction period. It has significant application value, good economic and social benefits.
Taking an double-span continuous arch bridge as an example (refer to FIG. 2), the single-rib construction method and the construction method with using the intelligent control cable to balance the unbalanced loading on the middle pier and its upper towers proposed in present invention, is a fast and safe construction method. The specific construction steps are summarized as follows:
- Step 1: (FIG. 7) Casting side pier 3, installing cable crane system 4, and then using the cable crane system 4 to cast middle pier 2.
- Step 2: (FIG. 8) Preferentially installing the longitudinal-left span transverse-left arch rib 101 and the longitudinal-right span transverse-left arch rib 103. The cable crane system 4 is located in the position of transverse-left arch rib. Installing the segment {circle around (1)} to segment {circle around (3)} transverse-left arch rib segments in sequence. After the segment on the side pier 3 is connected in the target position, extending the clasp cable and back clasp cable immediately, and then the clasp cable is extended immediately after the segment on the middle pier 2 is connected in the target position. The arch rib segment {circle around (1)} to arch rib segment {circle around (3)} do not require installing the intelligent control cable 6, relying on the stiffness of the middle pier 2 to resist unbalanced loading, until the installation of the arch rib segment {circle around (1)} to arch rib segment {circle around (3)} of the two transverse-left arch rib segments are completed.
- Step 3: (FIG. 9) Installing the arch rib segment {circle around (4)} on the two side piers 3, placing the arch rib segment {circle around (4)} on the right side of the middle pier, and then installing the intelligent control cable 6. The lower anchor point of the intelligent control cable 6 is set on the foundation of side pier 3, and the upper anchor point is set on the top of middle pier 2. When extending clasp cable 501 of the arch rib segment {circle around (4)} on the right side, the intelligent control cable 6 simultaneously applies intelligent control cable force, keeping middle pier 2 always in a vertical and balanced state.
- Step 4: (FIG. 10) Placing the arch rib segment {circle around (4)} on the left side of the middle pier 2, when extending clasp cable 501 of the arch rib segment {circle around (4)} on the left side, the intelligent control cable 6 releases its intelligent control cable force synchronously, keeping the middle pier 2 in a vertical and balanced state, and the intelligent control cable 6 does not need to be removed. (illustrated by dashed line in FIG. 10.)
- Step 5: (FIG. 11) Following the methods in steps 3 and 4, completing the installation of the arch rib segment {circle around (4)} to the arch rib segment {circle around (6)}.
- Step 6: (FIG. 12) Installing the anchorage tower 504, moving the upper anchor point of the intelligent control cable 6 to the top of anchorage tower 504 or the corresponding vertical position of the clasp cable 501 of segment {circle around (7)} on the right side of the anchorage tower 504. Then, installing segment {circle around (7)} on the two side piers, and then placing the segment {circle around (7)} on the right side of the middle pier. When extending clasp cable 501 of the arch rib segment {circle around (7)} on the right side, the intelligent control cable 6 simultaneously applies intelligent control tension force, maintaining the middle pier 2 always in a vertical and balanced state.
- Step 7: (FIG. 13) Placing the arch rib segment {circle around (7)} on the left side of the middle pier 2, when extending clasp cable 501 of the arch rib segment {circle around (7)} on the left side, the intelligent control cable 6 synchronously releases the intelligent control tension force, so that the middle pier 2 always maintains a vertical and balance state. Specially, the intelligent control cable 6 does not need to be removed. (illustrated by dashed line in FIG. 13.)
- Step 8: (FIG. 14) Following the methods described in steps 6 and 7, and then completing the installation of the arch rib segment {circle around (7)} to arch rib segment {circle around (9)}.
- Step 9: (FIG. 15) The longitudinal-left span transverse-left arch rib 101 and the longitudinal-right span transverse-left arch rib 103 are completed closure, the clasp cables 501 are symmetrically removed, and then switching to a single-arch rib closure state.
- Step 10: (FIG. 16) Moving the cable crane system 4 excluding the cable tower 401 to the transverse-right arch rib position. Completing the installation of the longitudinal-left span transverse-right arch rib 102 and the longitudinal-right span transverse-right arch rib 104 on the transverse-right arch rib following the above mentioned steps, then completing closure and symmetrically and orderly removing the clasp cables 501. Moving the cable crane system 4 excluding the cable tower 401 to the transverse brace position, lifting and installing the transverse brace, and then switching to a double-arch rib whole subjected state.
- Step 11: (FIG. 17) The subsequent construction procedures after the closure of the two arch ribs are finished, then the construction of the arch bridge is completed.
Patent Application
20250129556
