Construction method for underpinning pier

Abstract

The invention discloses a construction method for bridge pier underpinning. The construction method comprises the steps that a gate-type pier lower structure is newly built; prefabricating a steel cover beam; the steel cover beam is horizontally moved to the side edge of an original pier stand column through a beam body moving and transporting device; a temporary supporting system is built on the side edge of an original pier stand column, and an existing bridge is supported; the original pier stand column structure is dismantled; and the prefabricated steel cover beam is assembled in place. By implementing the construction method for underpinning the bridge pier, the existing bridge pier for operating the rail transit can be integrally, quickly and accurately underpinned in a narrow space. The steel cover beam is prefabricated and then transferred to the construction site, the problems that the existing bridge supporting structure is built in a cast-in-place mode on site, traffic is affected for a long time, the nearby environment is polluted are solved, and the stability of the existing bridge structure is guaranteed by being matched with a temporary supporting system and dismantling and transporting away an original bridge pier.

Description

Technical Field

[0001] The present invention relates to the technical field of underpinning construction of existing bridge structures, and in particular to a construction method for underpinning bridge piers. Background Art

[0002] With the rapid development of my country, the number of urban tunnels and railway tunnels is increasing. New tunnels often cross existing urban bridges and even conflict with the pile foundations of existing urban bridges. When the new tunnel cannot be avoided between the pile foundations of existing bridges, in order to reduce the impact of tunnel construction on the existing urban bridges, the commonly used method is to transfer the upper load of the existing bridge to the pile foundation or the overall underpinning structure through the pile foundation or the substructure, thereby achieving the smooth construction of the underground tunnel. Given that many of these projects are located in core areas with existing operating bridges and heavy traffic pressure, the only solution is to ensure the safety of people's livelihoods and residents' travel. This results in extremely limited construction time and construction efficiency. The construction methods must be extremely precise and precise.

[0003] Traditional construction methods often involve closing off ground access to existing bridges, constructing new substructures, and then reopening the existing bridges and ground traffic after the load-bearing system transition between the old and new structures is complete. This approach has wide-ranging impacts, particularly on livelihoods and public transportation. The method of the present invention effectively circumvents this problem, achieving seamless replacement and renewal.

[0004] In view of the working condition of the shield tunnel passing through the bridge pile foundation of the existing operating rail transit viaduct, a set of bridge pier replacement devices and construction methods were developed to realize the replacement construction of the existing bridge substructure, solving the difficult problem of rapid and refined replacement construction of existing bridge piers under extreme space conditions and while ensuring the normal operation of the operating rail transit.

[0005] This method is suitable for urban infrastructure construction scenarios where underground structures interfere with each other, where new tunnel structures clash with the substructure of existing rail transit bridges, and where replacement structures are needed to maintain the operation of existing bridges. It is also particularly useful for underpinning existing bridge piers in extreme spaces, confined spaces, and with extremely limited working time. This pier underpinning construction method offers significant advantages, including high efficiency, precision, safety, and low cost. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects in the prior art that the construction of bridge pier underpinning requires closing traffic and building a new existing bridge support structure on site, and to provide a construction method for bridge pier underpinning.

[0007] The present invention solves the above technical problems through the following technical solutions:

[0008] A construction method for bridge pier underpinning, comprising the following steps:

[0009] S1. New portal pier substructure;

[0010] S2. Prefabricated steel cap beam;

[0011] S3. The steel cap beam is moved to the side of the original pier column by the beam transfer device;

[0012] S4. Build a temporary support system on both sides of the original bridge pier columns to support the existing bridge;

[0013] S5. dismantling the original pier column structure;

[0014] S6. Assemble the prefabricated steel cap beam into place.

[0015] This proposal utilizes a pier replacement construction method that allows for the rapid and precise replacement of existing rail transit piers within a confined space. Prefabricated steel cap beams are then transported to the construction site, eliminating the need to construct existing bridge support structures on-site, which would have long-term impacts on traffic and polluted the surrounding environment. A temporary support system is then used to dismantle and remove the existing piers, ensuring the stability of the existing bridge structure.

[0016] Preferably, the portal pier substructure includes a pile foundation, a cap and a pier column, and the step S1 further includes the following steps:

[0017] S1.1. The pile foundation, the cap and the pier are formed by drilling deep into the ground, excavating, planting reinforcement and pouring;

[0018] S1.2. After the construction of the foundation is completed, pre-stress the lower structure of the portal pier.

[0019] In this solution, the overall strength of the portal pier substructure is ensured by pouring pile foundations underground. After the cap is constructed, the substructure is pre-stressed to induce a certain degree of compression deformation in the foundation soil. This reduces the subsequent settlement of the portal pier substructure during the working phase and allows for a closer integration of the portal pier substructure with the foundation, improving stability and safety.

[0020] Preferably, the beam moving device includes two modular vehicles, which are respectively arranged under the two ends of the steel cap beam, so that the length direction of the steel cap beam moves perpendicular to the extension direction of the existing bridge.

[0021] In this solution, two modular vehicles are set up to support transportation at both ends, making the transportation work more stable. The modular vehicle has a high carrying capacity, multiple steering modes, can turn 360° on the spot, has stable and reliable travel, strong driving ability, remote control, high precision, and can achieve transportation without the need for other tools.

[0022] Preferably, the temporary support system includes steel supports, distribution beams, jacks and pads, a temporary jacking foundation, and pads, and step S4 further includes the following steps:

[0023] S4.1. Lay pads on the ground and / or on the temporary foundation and existing caps;

[0024] S4.2. A plurality of steel supports are provided on the pad, wherein the plurality of steel supports are arranged side by side;

[0025] S4.3. Lift the distribution beam onto the steel support beam, with the distribution beam perpendicular to the extension direction of the existing bridge;

[0026] S4.4. A plurality of jacks are provided on the distribution beam, and the jacks support the bottom of the existing bridge upward.

[0027] In this solution, pads are first installed to prevent damage to the road surface or foundation during subsequent construction. Steel supports are then placed on the pads to disperse stress. The distribution beam is placed above multiple steel supports, preventing it from tipping or moving. Multiple support beams can simultaneously bear the weight of the distribution beam, providing a more stable support effect. The support is supported by jacks, allowing for adjustable height at any time. The small size of the support also prevents it from interfering with the layout of other structures.

[0028] Preferably, column tie beams are connected between the original pier columns, and step S5 further includes the following steps:

[0029] S5.1. The module car is set at the bottom of the column tie beam and pre-top of the column;

[0030] S5.2. Use cutting equipment to cut the original pier column, dividing the original pier column into an upper half column and a lower half column;

[0031] S5.3. Lift the column tie beam and the upper column by means of the module vehicle roof, and translate them until the upper column leaves the lower column.

[0032] In this solution, the existing pier columns were cut into upper and lower halves. Removing the upper half of the columns created space for the steel cap beam to be moved into place. The lower half would be removed after the load-bearing system of the steel cap beam was converted.

[0033] Preferably, the cutting device is a wire saw device.

[0034] In this solution, cutting is performed using a wire saw, which has a relatively fast cutting speed and will not delay the construction progress. The operator can perform operation control at a relatively safe distance, which has high operation safety. In addition, the dust generated during the wire saw cutting process is relatively small and will not pollute the environment.

[0035] Preferably, the step S6 further includes the following steps:

[0036] S6.1. Move the steel cap beam to the top of the portal pier substructure and form a space between the steel cap beam and the portal pier substructure;

[0037] S6.2. Provide a temporary support structure on the portal pier substructure to support the steel cap beam;

[0038] S6.3. Steel supports are provided between the steel cap beam and the portal pier substructure.

[0039] In this solution, a temporary support structure is used to support the steel cap beam, so that a certain working space is formed between the steel cap beam and the lower structure of the portal pier to facilitate subsequent operations. Steel supports are set on the lower structure of the portal pier to provide stable support for the steel cap beam and avoid displacement due to vibration during use.

[0040] Preferably, the steel support includes a support anchor rod below the step S63, further comprising the steps of:

[0041] S6.3.1. Provide holes on the substructure of the portal pier;

[0042] S6.3.2. Place a bolt sleeve in the hole;

[0043] S6.3.3. Set the support anchor rod vertically in the hole and connect it with the bolt sleeve.

[0044] In this solution, holes are set to connect with the support anchor rods to make the overall connection more secure.

[0045] Preferably, after step S6, the method further comprises the following steps:

[0046] S7. Dismantle the temporary support system.

[0047] In this plan, after the integral steel cap beam and the portal pier substructure are installed in place, the temporary support structure can be removed and the construction site can be cleaned to provide safety guarantees for subsequent traffic restoration.

[0048] Preferably, the step S7 further includes the following steps:

[0049] S7.1 cooperate with the temporary support structure, slowly unloading the jack on the distribution beam;

[0050] S7.2. Using a forklift to dismantle the distribution beam and the steel support;

[0051] S7.3. Remove the existing bridge pier columns.

[0052] In this plan, each supporting component is removed in turn, and the steel cap beam is lifted and supported by a temporary supporting structure to support the weight of the existing bridge. The jacks on the distribution beam are then slowly unloaded until the steel cap beam is stressed and the force system conversion is completed. The jacks are removed so that the distribution beam no longer supports the existing bridge. The distribution beam and steel support are then removed to leave preparation space for the removal of the lower half of the bridge piers. The original bridge pier columns are then completely removed to complete the removal of the temporary structure at the construction site and the original existing bridge structure. The overall demolition work is safe and orderly, facilitating the subsequent rapid restoration of traffic.

[0053] The positive impact of this invention lies in the fact that, through the implementation of this pier underpinning construction method, the piers of existing rail transit can be quickly and accurately replaced in a confined space. By prefabricating the steel cap beam and then transporting it to the construction site, the existing bridge support structure is avoided, which would cause long-term traffic disruptions and pollute the surrounding environment. By using a temporary support system, the original piers can be removed and transported, ensuring the stability of the existing bridge structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 Schematic diagram of the steps of a construction method for pier underpinning in an embodiment of the present invention;

[0055] Figure 2 This is a flow chart of step S4 of the construction method for pier underpinning in an embodiment of the present invention;

[0056] Figure 3 This is a flow chart of step S5 of the construction method for pier underpinning in an embodiment of the present invention;

[0057] Figure 4 This is a flow chart of step S6 of the construction method for pier underpinning in an embodiment of the present invention;

[0058] Figure 5 This is an overall schematic diagram of a bridge pier in an embodiment of the present invention;

[0059] Figure 6 Schematic diagram of a temporary support system in an embodiment of the present invention;

[0060] Figure 7 Schematic diagram of the steel cap beam before placement and the cutting and translation of the columns in an embodiment of the present invention;

[0061] Figure 8 This is a schematic diagram of the steel cap beam during movement in an embodiment of the present invention;

[0062] Figure 9 This is a schematic diagram of the steel cap beam in place in an embodiment of the present invention;

[0063] Figure 10 It is a schematic cross-sectional view of the foundation and steel support structure in an embodiment of the present invention.

[0064] Description of reference numerals:

[0065] Existing bridge 1

[0066] Platform 2

[0067] Pier 3

[0068] Original pier column 4

[0069] Upper column 41

[0070] Lower half column 42

[0071] Modular Car 5

[0072] Steel cap beam 6

[0073] Distribution beam 7

[0074] Steel support 8

[0075] Column tie beam 9

[0076] Lifting equipment 10

[0077] Wire saw equipment11

[0078] Jack 12

[0079] Support anchor 13

[0080] Template 14

[0081] Steel support 15

[0082] Temporary jack 16

[0083] Hole 17

[0084] Existing platform 18

[0085] Temporary Foundation 19

[0086] Pad 20 DETAILED DESCRIPTION

[0087] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0088] In this embodiment, a construction method for pier underpinning is provided, such as Figures 1-10 As shown, the steps include:

[0089] S1. New portal pier substructure;

[0090] S2. Prefabricated steel cap beam 6;

[0091] S3. The steel cap beam 6 is moved to the side of the original pier column 4 by the beam transfer device;

[0092] S4. Build a temporary support system on both sides of the original pier column 4 and support the existing bridge 1;

[0093] S5. Remove part of the original pier column 4 structure;

[0094] S6. Assemble the prefabricated steel cap beam 6 into place.

[0095] This pier replacement construction method allows for the rapid and precise replacement of existing rail piers within a confined space. Prefabricating the steel cap beam 6 and then transporting it to the construction site avoids the need to construct the existing bridge support structure on-site, which would have disrupted traffic for a long time and polluted the surrounding environment. By using a temporary support system, the existing piers can be removed and transported, ensuring the stability of the existing bridge structure.

[0096] In this embodiment, if Figure 5 As shown, the portal pier substructure includes a pile foundation, a cap 2 and a pier column 3, and step S1 also includes the following steps:

[0097] S1.1. Form the pile foundation, cap 2 and pier 3 by drilling and pouring deep into the ground;

[0098] S1.2. After the construction of foundation 2 is completed, pre-stress the substructure of the portal pier.

[0099] The overall strength of the portal pier's substructure is ensured by pouring pile foundations underground. After the construction of Platform 2 is completed, the substructure is pre-stressed to induce a certain degree of compression deformation in the underlying soil. This reduces the subsequent settlement of the portal pier's substructure during the working phase and allows for a closer integration of the substructure with the underlying soil, improving stability and safety.

[0100] Specifically, the newly constructed portal pier columns 3 are constructed using cast-in-place reinforced concrete, measuring 3.3m (length) x 2.8m (width) x 2m (height). Bored piles are used for the foundation construction. To reduce post-construction settlement, post-grouting is applied to the pile ends. After the construction of the cap 2 is completed, the substructure is preloaded with a weight equal to 1.1 times the post-underpinning superstructure deadweight plus the vehicle load. The preloading period is three days, and the preloading is terminated when the pile foundation settlement is less than 1mm after 24 hours or less than 5mm after 72 hours.

[0101] Furthermore, the beam transport device includes two modular vehicles 5, namely SMPT hydraulic flatbed vehicles, equipped with jacking equipment 10. The modular vehicles 5 are respectively positioned below the ends of the steel cap beam 6, so that the length direction of the steel cap beam 6 can be moved perpendicular to the extension direction of the existing bridge 1. The two modular vehicles 5 are respectively arranged at both ends to support the transportation, making the transportation operation more stable. The modular vehicles 5 have a high load capacity, multiple steering modes, and can turn 360 degrees on the spot. They travel smoothly and reliably, have strong driving ability, are remotely controlled, and have high precision. They can be transported without the need for other tools.

[0102] In this embodiment, the foundation is treated before the construction of the temporary support system. The site is leveled to 4.2 m, and a temporary foundation 19 for the reaction force of the steel support 8 is constructed on both sides of the existing abutment 18 of the corresponding pier. The temporary foundation 19 has a size of 1.8 m * 6.55 m * 1.0 m, and the foundation bearing capacity is required to be 150 kPa. High-pressure jet grouting (MJS method pile) is used for construction.

[0103] In this embodiment, the temporary support system includes steel supports 8, distribution beams 7, jacks 12 and pads 20, and step S4 further includes the following steps:

[0104] S4.1. Lay pads on the temporary foundation 19 and the existing cap 18.

[0105] S4.2. A plurality of steel supports 8 are provided on the pad, and a plurality of steel supports 8 are provided side by side;

[0106] S4.3. Lift the distribution beam 7 onto the steel support 8, with the distribution beam 7 perpendicular to the extension direction of the existing bridge 1;

[0107] S4.4. A plurality of jacks 12 are provided on the distribution beam 7 , and pads 20 are provided on the jacks 12 to support the bottom of the existing bridge 1 upward.

[0108] The pads are first installed to prevent damage to the road surface, existing piers 18, and temporary foundations 19 during subsequent construction. Steel supports 8 are placed on the pads to disperse stress. Distribution beam 7, positioned above multiple steel supports 8, is prevented from easily tipping or moving. Multiple support beams can simultaneously bear the weight of distribution beam 7, providing a more stable support effect. Pads 20 are placed above jacks; jacks 12 support the existing bridge track beams, allowing for adjustable support heights. The compact design does not affect the layout of other structures.

[0109] Specifically, if Figure 6 As shown, in this embodiment, the size of the steel support 8 is There are four beams on each side, with the distribution beam 7 measuring 0.5m*0.8m*6m. The jacks 12 are configured to be 200t, a total of eight, and the pads 20 are 450x450x20mm in size. The steel supports 8 are constructed during the day and installed using a combination of forklifts and manual labor. After the steel supports 8 are installed, a 10t forklift is used to lift the distribution beam 7 onto the steel supports 8. The 450x450x20mm pads 20 are placed on the web of the track beams of the existing bridge 1. The purpose of these pads 20 is to increase the load-bearing area of ​​the jack caps and prevent cracking of the track beams due to insufficient local pressure bearing capacity.

[0110] Hereby explain, the steel support layout principles:

[0111] (1) The jacking point is 3.1m away from the bridge span line;

[0112] (2) The layout of the steel supports must meet the space requirements for the steel cap beam 6 and the cutting and removal of the original pier columns 4.

[0113] Specifically, the steel supports are arranged as follows: Along the bridge, the steel supports are located 3.1m from the span line, with their centers 2.35m from the outer edges of the existing piers. The clear distance between the steel supports and the piers is 1.98m (the total width of the steel cap beam 6 is 1.8m). Across the bridge, the clear distance between the piers is 2.7m (the width of the modular vehicle 5 is 2.43m). Four sets of steel supports are arranged, with the center-to-center spacing of the inner steel supports 3.43m and the center-to-center spacing of adjacent steel supports 0.86m to ensure that the inner steel supports do not interfere with the modular vehicle 5's movement through the center of the piers.

[0114] Preferably, the original pier columns 4 are connected with column tie beams 9, and step S5 further includes the following steps:

[0115] S5.1. The module car is set at the bottom of the column tie beam and pre-top of the column;

[0116] S5.2. Use cutting equipment to cut the original pier column 4 and divide the original pier column 4 into an upper column and a lower column;

[0117] S5.3. Lift the column tie beam 9 and the upper half of the column by the module vehicle 5 and move them horizontally along the other side of the column until the upper half of the column leaves the lower half of the column.

[0118] Specifically, the existing pier columns 4 are cut into upper and lower halves 41 and 42. Removing the upper half of the columns creates space for the steel cap beam 6 to be moved into position. A modular vehicle 5 supports the column beam system. The modular vehicle 5 located here and the modular vehicle 5 below the steel cap beam 6 serve different purposes, allowing them to move independently without interfering with each other. This prevents the pier columns from sinking and jamming the cutting equipment during cutting, ensuring a smooth cutting process. Removing the upper half of the columns via the modular vehicle 5 facilitates subsequent transport and reserves space for the subsequent translation of the steel cap beam 6 into position.

[0119] Furthermore, if Figure 7 As shown, the cutting device is a wire saw device 11 .

[0120] In this solution, cutting is performed by the wire saw device 11, and the cutting speed is relatively fast, which will not delay the construction progress. The operator can perform operation control at a relatively safe distance, and the operation is highly safe. In addition, the dust generated during the wire saw cutting process is relatively small, which will not pollute the environment.

[0121] Other auxiliary tasks are performed during the cutting process, including positioning the wire saw machine and aerial platform. Positioning guide wheels are installed during wire saw cutting to prevent the wire saw from hitting the lifting steel support 8. Baffles are also installed on the sides and rear of the cutting machine for protection.

[0122] Hereby explain, the principles of cutting position arrangement:

[0123] (1) The module vehicle 5 must be able to drive in and lift the column tie beam 9;

[0124] (2) There is space for the steel cap beam 6 to move in horizontally.

[0125] In this embodiment, the hydraulic jack system of the temporary support system on both sides of the existing column performs a trial jacking operation before formal jacking to ensure that the PLC system works normally and various monitoring indicators are controllable. The jacking steps and requirements are as follows. Jacking is performed in stages in units of 1mm, 2mm, 5mm, and 10mm until it is ensured that the jacking PLC system operates normally and the monitoring indicators are controllable. After jacking to 10mm, the jack 12 maintains pressure and self-locks. The rail beam support can only be removed after it is empty. After the removal is completed, the column cutting begins. The settlement or uplift change rate of the subway structure caused by construction is less than 10mm.

[0126] After the support above the column is removed, a gap of 10 + 57 = 67 mm of support thickness remains above the column, allowing the existing column to be removed with a single cut. To facilitate the removal of the existing pier column 4, both existing pier columns 4 are cut with beveled surfaces. The cut surface on the column removal side is 3.08 m from the top of the column, and 3.05 m on the other side. Both columns are cut simultaneously. Before cutting, the modular vehicle 5 is positioned at the bottom of the column tie beam and pre-jacks the column. During the cutting process, to prevent the existing pier column 4 from sinking and the clamping rope, the modular vehicle 5 below the column tie beam 9 applies a lifting force equal to 80% of the weight of the cut portion of the existing pier column 4, ensuring a smooth cutting process.

[0127] Specifically, in this embodiment, the modular vehicle 5 is first lifted 1 cm to remove the existing steel liner plates on the pier columns 4, ensuring that the upper and lower columns are completely separated during translation. The vehicle is then translated 1.85 m to the other side of the steel cap beam 6 to allow for translation. During the translation, a monitoring operator on the modular vehicle 5 below the column tie beam 9 observes the translation stop markings and red and white stop signs on the ground in real time. The modular vehicle 5 below the column tie beam 9 translates at a constant speed of 10 cm / min until it is in place (8-10 cm from the steel support).

[0128] In this embodiment, step S6 further includes the following steps:

[0129] S6.1. Move the steel cap beam 6 to the top of the portal pier substructure and form a space between the steel cap beam 6 and the portal pier substructure;

[0130] S6.2. Install temporary jacks 16 on the portal pier substructure and support the steel cap beam 6;

[0131] S6.3. Set steel supports 15 between the steel cap beam 6 and the portal pier substructure.

[0132] Temporary jacks 16 are used to support the steel cap beam 6, so that a certain working space is formed between the steel cap beam 6 and the lower structure of the portal pier to facilitate subsequent operations. Steel supports 15 are set on the lower structure of the portal pier to provide stable support for the steel cap beam 6 and avoid displacement caused by vibration during use.

[0133] Specifically, if Figure 8 As shown, in this embodiment, the beam transport and erection device (two modular vehicles 5 under the steel cap beam 6) is used to lift the steel cap beam 6 as a whole to 5 cm above the design elevation. In addition, a 4 cm height is reserved for grouting the supports above the columns. At this time, the total clearance for the support installation is 9 cm.

[0134] Furthermore, the steel support 15 includes the support anchor rod 13 in step S63, further comprising the following steps:

[0135] S6.3.1. Provide hole 17 on the portal pier substructure;

[0136] S6.3.2. Place the bolt sleeve in hole 17;

[0137] S6.3.3. Set the support anchor rod 13 vertically in the hole 17 and connect it with the bolt sleeve.

[0138] The holes are provided to connect with the support anchor rods 13 to make the overall connection more secure.

[0139] Among them, Figure 9-10 As shown, the newly constructed columns have reserved support holes 17. A 5cm thick grouting depth is reserved in the portal pier substructure to ensure sufficient clearance above the steel cap beam 6 for installation of the track beam slab support. The anchor rods and bolt sleeves under the supports must be placed vertically in the holes in advance and clamped securely at the top with tools to prevent them from slipping. Once the steel cap beam 6 is in place, the screw rods and sleeves under the supports are manually connected through the holes. Once the cap beam 6 is in place, the cap beam is lowered to the initial design elevation. After the beam is lowered, a boom lift is used in conjunction with manual labor to complete the installation and placement of the track beam slab support.

[0140] Furthermore, during the grouting of the permanent steel supports 15, the steel formwork 14 is prepared in advance and coated with a release agent on the inner wall. The formwork 14 is tied together to prevent grouting. The grouting material uses an early-strength grouting material according to design requirements, reaching 20 MPa in 2 hours. Only after the support grouting material reaches 20 MPa can the temporary jacks 16 under the track beam be slowly unloaded until the steel cap beam is loaded and the load system transition is complete. Meanwhile, relevant units inspect the line to ensure that it meets traffic requirements and the underpinning is completed.

[0141] In this embodiment, after step S6, the following steps are further included:

[0142] S7. Remove the temporary support system.

[0143] After the integral steel cap beam 6 and the portal pier substructure are installed in place, the temporary jacks 16 can be removed and the construction site can be cleaned to provide safety guarantees for subsequent traffic restoration.

[0144] Specifically, the two modular vehicles 5 below the two ends of the steel cap beam 6 and the jacking equipment 10 on the modular vehicles 5 need to be evacuated to avoid disturbing the cap beam; the temporary jacks 16 below the steel cap beam 6 serve as fulcrums to transmit the load of the steel cap beam 6 to the pier 3 and the pedestal 2 below, and various parameters are controlled according to the elevation required by the design to meet the beam drop conditions. The jacks 12 under the track beam are slowly unloaded at a speed of no more than 3mm / min until the steel cap beam 6 is stressed and the force system conversion is completed; after the force system conversion is completed, the deflection and deformation of the steel cap beam are monitored; according to the changes in the deflection and displacement of the cap beam, the temporary jacks 16 are used to fine-tune the cap beam elevation so that the track beam elevation is the same as the original elevation. After the elevation is correct, the temporary jacks 16 are mechanically screwed and locked.

[0145] In this embodiment, step S7 further includes the following steps:

[0146] S7.1. With the temporary jack 16, slowly unload the jack 12 on the steel support 8;

[0147] S7.2. Use a forklift to dismantle the distribution beam 7 and the steel support 8;

[0148] S7.3. Remove the upper half of the existing pier column 4.

[0149] Each supporting component is removed in sequence. Using temporary jacks 16, the steel cap beam 6 is lifted and supports the weight of the existing bridge 1. The jacks 12 on the distribution beam 7 are then slowly unloaded until the steel cap beam 6 is loaded and the load system conversion is complete. Jacks 12 are removed so that the distribution beam 7 no longer supports the existing bridge 1. The distribution beam 7 and steel supports 8 are then removed, allowing for the complete removal of the upper half of the columns, leaving space for the complete removal of the upper half of the columns 41 of the original pier columns 4. This completes the removal of the temporary construction site structure and the upper half of the columns 41 of the existing bridge 1. The overall removal is safe and orderly, facilitating the rapid restoration of traffic. The remaining lower half of the columns 42 will be handled later.

[0150] In this embodiment, due to the high height of the jacks 12 and distribution beam 7, attention must be paid to construction safety during removal. When dismantling the equipment, the jacks 12 must first be secured with a winch before removal. They must then be safely lowered one by one using an electric winch. They must not be dropped directly from the construction platform. After the jacks 12 are removed, the distribution beam 7 can be removed. A 10t forklift is used for removal. The steel supports 8 are manually removed section by section using a forklift with slings. Safety must be observed during the support removal process. Steel sections must not be thrown around randomly. Heavy objects must be handled with mechanical assistance and under the supervision of a dedicated person.

[0151] For the record, in this invention, both pre-underpinning preparations and the underpinning phase undergo rigorous and precise data monitoring and measurement to ensure the accuracy and reliability of each process. This includes monitoring the elevation of the existing bridge 1, measuring the elevation of the existing bridge 1 after jacking up, measuring the position of the steel cap beam 6, and cutting and removing the columns 4. Subsequent processes can only proceed after the measurement and monitoring data at each step meets the required standards.

[0152] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of the present invention.

Claims

1. A construction method for bridge pier underpinning, characterized in that: The steps include: S1. New portal pier substructure; S2. Prefabricated steel cap beam; S3. The steel cap beam is moved to the side of the original pier column by the beam transfer device; S4. Build a temporary support system on the sides of the original bridge pier columns to support the existing bridge; S5. dismantling the original pier column structure; S6. Assemble the prefabricated steel cap beam into place.

2. The construction method for bridge pier underpinning according to claim 1, wherein the portal pier substructure includes a pile foundation, a cap, and a pier column, and step S1 further comprises the following steps: S1.

1. The pile foundation, the cap and the pier are formed by drilling and pouring deep into the ground; S1.

2. After the construction of the foundation is completed, pre-stress the lower structure of the portal pier.

3. In the construction method for replacing piers as described in claim 1, the beam moving device includes two modular vehicles, which are respectively arranged under the two ends of the steel cap beam, so that the length direction of the steel cap beam moves perpendicular to the extension direction of the existing bridge.

4. The pier underpinning construction method according to claim 1, wherein the temporary support system comprises steel supports, distribution beams, jacks, and pads, and step S4 further comprises the following steps: S4.

1. Lay pads on the ground; S4.

2. A plurality of steel supports are provided on the pad, wherein the plurality of steel supports are arranged side by side; S4.

3. Lift the distribution beam onto the steel support, with the distribution beam perpendicular to the extension direction of the existing bridge; S4.

4. A plurality of jacks are provided on the distribution beam, and the jacks support the bottom of the existing bridge upward.

5. The method for bridge pier underpinning according to claim 1, wherein the original pier columns are connected by column tie beams, and step S5 further comprises the following steps: S5.

1. The module car is set at the bottom of the column tie beam and pre-top of the column; S5.

2. Use cutting equipment to cut the original pier column, dividing the original pier column into an upper half column and a lower half column; S5.

3. Lift the column tie beam and the upper half column via the module vehicle roof, and translate until the upper half column leaves the lower half column.

6. The construction method for bridge pier underpinning according to claim 5, wherein the cutting device is a rope saw device.

7. The method for bridge pier underpinning according to claim 1, further comprising the following steps in step S6: S6.

1. Move the steel cap beam to the top of the portal pier substructure and form a space between the steel cap beam and the portal pier substructure; S6.

2. Provide a temporary support structure on the portal pier substructure to support the steel cap beam; S6.

3. Steel supports are provided between the steel cap beam and the portal pier substructure.

8. The method for bridge pier underpinning according to claim 7, wherein the steel support includes support anchor rods below the steel support. In step S63, the method further comprises the following steps: S6.3.

1. Provide holes on the substructure of the portal pier; S6.3.

2. Place a bolt sleeve in the hole; S6.3.

3. Set the support anchor rod vertically in the hole and connect it with the bolt sleeve.

9. The method for bridge pier underpinning according to claim 4, further comprising, after step S6: S7. Dismantle the temporary support system.

10. The construction method for pier underpinning according to claim 9, further comprising the following steps in step S7: S7.1 cooperate with the temporary support structure, slowly unloading the jack on the distribution beam; S7.

2. Using a forklift to dismantle the distribution beam and the steel support; S7.

3. Remove the existing bridge pier columns.

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