A construction method for circumferential road synchronous settlement type viaduct pier

Abstract

The present invention discloses a construction method for a circumferential road synchronously subsided elevated bridge pier, comprising forming a cap, forming a pier, and laying a circumferential road around the cap; the cap forming comprises excavating a foundation pit, installing a steel reinforcement frame of the cap, installing a cap formwork, pouring cap concrete, and removing the cap formwork; the pier forming comprises installing a pier formwork, installing a construction platform, pouring pier concrete, and removing the pier formwork; the circumferential road around the cap comprises installing side baffles, backfilling the foundation pit with original soil, backfilling with pond slag, laying graded gravel, laying a cement base, and laying an asphalt pavement; the side baffle installation comprises: installing side baffles perpendicular to the top surface of the cap on both sides of the top surface of the cap close to the road, aligning the outer sides of the side baffles with the side surfaces of the cap, and providing an isolation layer on the outer sides of the side baffles and the side surfaces of the cap. The present invention can effectively alleviate bulging of roads around pier caps and is particularly suitable for elevated bridge construction in areas with soft soil.

Description

Technical Field

[0001] The invention relates to the technical field of viaduct construction, in particular to a construction method for circumferential road synchronously sinking viaduct piers. Background Art

[0002] Viaducts are an important part of urban road traffic. With the development of cities, the number of viaducts is bound to increase. At present, the construction of domestic viaducts has no obvious regional distinction. However, the same construction technology cannot achieve the same effect in different regions. For some southern coastal cities, such as Ningbo, many of the built viaducts have asphalt pavement bulges around the piers, which greatly affects the comfort of vehicle driving. At the same time, the pavement structure in the bulging area is easily damaged, increasing the cost of repair and maintenance.

[0003] This phenomenon occurs because many southern coastal cities are typically located in soft soil areas. The thickness of the miscellaneous fill (miscellaneous fill) and weak soil layers (silty clay) can reach over 30 meters, resulting in extremely weak bearing capacity and a high risk of settlement. During current viaduct pier construction, after the abutment and pier construction is completed, the perimeter of the viaduct is backfilled with materials that strengthen the road structure around the abutment (conventional viaduct pier abutments are backfilled with graded crushed stone for structural reinforcement). This reduces road settlement around the abutment and strengthens the pavement around the abutment. Furthermore, during conventional road construction around the abutment, multiple layers of steel wire grating are extended from the roadside to the planted soil area above the abutment. In soft soil areas, the long-term, slow subsidence of the soft soil causes the road surface outside the 2.0 m radius of the abutment to settle much faster than the road surface within that radius. This, combined with the effects of the multiple layers of steel wire grating and backfill reinforcement, can easily cause bulging around the abutment.

[0004] There are currently four mainstream approaches to addressing the issue of road bulging around elevated bridge caps. First, increase the thickness of the road structure layer and improve the road compaction to prevent or minimize road sinking; second, increase the buried depth of the cap to reduce uneven road settlement; third, increase the width of the green belt to keep the road away from the impact zone of the cap; and fourth, cut corners on the cap. While these four approaches are theoretically feasible, their practical implementation reveals that: The first approach, based on current circumstances, would significantly increase project costs while offering limited effectiveness; the second approach, currently designed for elevated bridge caps, is generally buried at a depth of around 1.5 meters. Only when the cap depth reaches 4 meters or more can the bulging around the cap be effectively alleviated. However, at this point, the excavation depth of the construction pit would reach over 6 meters, significantly increasing both the construction risk and the project cost; the third approach, given the current shortage of construction land, is also difficult to implement; and the fourth approach, due to the significant reverse force exerted by the angled surface on the road fill structure, is also ineffective.

[0005] Therefore, in view of the land properties of soft soil areas in southern coastal cities, it is urgent to adapt the existing viaduct pier construction technology to alleviate the problem of road bulging around the viaduct piers. Summary of the Invention

[0006] The present invention aims to provide a method for constructing circumferential road synchronously sinking elevated bridge piers. The method can effectively alleviate bulging of roads around the pier caps and is particularly suitable for elevated bridge construction in soft soil areas.

[0007] The technical solution of the present invention is a construction method for piers of a circumferential road synchronously subsidence-type elevated bridge, which includes forming a cap, forming a pier, and paving a circumferential road of the cap;

[0008] The said cap forming includes excavating a foundation pit, installing a steel frame of the cap, installing a cap formwork, pouring concrete for the cap and removing the cap formwork; retaining the original soil of the foundation pit when excavating the foundation pit;

[0009] The pier column forming includes the installation of pier column formwork, the installation of construction platform, the pouring of pier column concrete and the removal of pier column formwork;

[0010] The paving of the road around the platform includes the installation of side baffles, backfilling of original soil in the foundation pit, backfilling of pond residue, paving of graded crushed stones, paving of cement base and paving of asphalt pavement;

[0011] The side baffle installation includes: installing side baffles perpendicular to the top surface of the platform on both sides of the top surface of the platform close to the road, aligning the outer sides of the side baffles with the side surfaces of the platform, and providing an isolation layer between the outer sides of the side baffles and the side surfaces of the platform;

[0012] The backfilling of the original soil of the foundation pit includes: filling the original soil of the foundation pit in the gaps around the foundation pile in the foundation pit, so that the height of the original soil of the foundation pit in the gaps is backfilled to the same height as the original soil layer before the foundation pit is excavated.

[0013] Compared with the prior art, the beneficial effects of the present invention are reflected in that the present invention successively completes the formation of the foundation pile, the formation of the pier and the paving of the circumferential road of the foundation pile, wherein the original soil of the foundation pit is retained for standby use when the foundation pile is formed and excavated, so as to be reused when the circumferential road of the foundation pile is paved. Specifically, the present invention installs side baffles to increase the height of the contact surface between the pedestal and the road structure when paving the circumferential road of the pedestal, and sets a low-friction resistance material as an isolation layer on the contact surface, thereby completely separating the pedestal from the road structure. At this time, the original soil of the foundation pit is retained when digging the foundation pit, and it is backfilled into the gap around the pedestal in the foundation pit, and backfilled to the same height as the original soil layer before the foundation pit was excavated. The filling material, thickness and compaction degree of the upper road structure are consistent with the road structure layer in other parts, ensuring that the materials at each depth of the road structure layer are consistent, and finally the circumferential road outside the pedestal can be synchronously settled. Although the settlement amplitude of the pedestal itself will be smaller than the settlement amplitude of the circumferential road, since the pedestal and the road structure are completely separated, there will be no obvious bulging phenomenon on the road surface around the pedestal, which can effectively ensure the comfort of vehicle driving.

[0014] In the aforementioned construction method of a circumferential road synchronously sinking elevated bridge pier, the side baffle is C-shaped as a whole and is arranged along the edge of the top surface of the pedestal. The side baffle includes a baffle body, and support plates perpendicular to the baffle body are respectively provided on both sides of the baffle body; the support plates are pre-embedded with anchor bars, and the top surface of the pedestal is provided with blind holes for inserting the anchor bars.

[0015] In the aforementioned method for constructing piers of a circumferential road synchronously sinking elevated bridge, the production of the side baffles includes the following steps:

[0016] a1. Build a steel frame according to the shape of the side panels and embed anchor bars in advance;

[0017] a2. Build several templates around the steel frame of the side baffle according to the shape of the side baffle. The templates outside the baffle body are made of PTFE sheets, and the rest are made of wood.

[0018] a3. Pour concrete and form side baffles after the concrete solidifies;

[0019] a4. Remove all wooden formwork connected to the side baffles, retain the Teflon plates connected to the side baffles, and the side baffles are prefabricated.

[0020] In the aforementioned method for constructing piers of a circumferential road synchronously sinking elevated bridge, the installation of the side baffles includes the following steps:

[0021] b1. Pour rebar glue into all blind holes on the top surface of the bearing platform;

[0022] b2. Take the prefabricated side baffles, align the pre-embedded anchor bars of the side baffles with the blind holes, and insert them until the bottom surface of the side baffles is in contact with the top surface of the pedestal. The amount of anchor glue used in step b1 is sufficient to ensure that the anchor glue overflows from the blind holes immediately before the bottom surface of the side baffles is in contact with the top surface of the pedestal.

[0023] b3. Clean the side of the pedestal corresponding to the side baffle, and use cement nails or nail-free glue to fix the PTFE plate on the entire side of the pedestal, so that the PTFE plate fixed on the side of the pedestal and the PTFE plate on the outside of the side baffle are connected to form a whole with only one seam. The two spliced ​​PTFE plates serve as an isolation layer for the transition between the pedestal and the road.

[0024] In the aforementioned construction method of a circumferential road synchronously sinking elevated bridge pier, the road outside the pier includes an original soil layer at the bottom layer, a first steel wire grid is laid on the top surface of the original soil layer, a first pond slag layer is laid above the first steel wire grid, a second steel wire grid is laid on the top surface of the first pond slag layer, a second pond slag layer is laid above the second steel wire grid, and a graded crushed stone layer, a cement stabilized crushed stone lower base layer, a cement stabilized crushed stone upper base layer and an asphalt pavement layer are sequentially arranged above the second pond slag layer.

[0025] In the aforementioned construction method of a circumferential road synchronously sinking elevated bridge pier, the pedestal and side baffles are completely isolated from the road by an isolation layer, the top surface of the side baffles is flush with the top surface of the cement-stabilized gravel subbase, fine stone concrete is provided on one end of the top surface of the cement-stabilized gravel subbase near the side baffles, and mutually perpendicular road curbs and road flat stones are embedded in the top of the fine stone concrete, the top surface of the road flat stones is flush with the top surface of the asphalt pavement layer, and the inside of the side baffles and fine stone concrete is filled with planting soil.

[0026] In the aforementioned construction method of a circumferential road synchronously sinking elevated bridge pier, the isolation layer is separated from the first pond slag layer and the second pond slag layer by an air fault structure, and the air fault structure includes a C-shaped isolation plate, the C-shaped opening of the isolation plate is against the outer side surface of the isolation layer, so that the isolation layer and the isolation plate cooperate to form a closed air layer; the bottom of the isolation plate is fixedly connected to the first steel wire grid, and the outer side wall of the isolation plate is fixedly connected to the second steel wire grid.

[0027] In the aforementioned construction method of a circumferential road synchronously sinking elevated bridge pier, a gap layer is provided between the top of the isolation plate and the graded gravel layer, and the gap layer is filled with sand and gravel; the graded gravel layer is filled with graded gravel, and the graded gravel particle size of the graded gravel filled in the graded gravel layer gradually decreases from far to near the isolation layer.

[0028] In the aforementioned construction method of a circumferential road synchronously sinking elevated bridge pier, a reinforcing plate connected to the inner side wall of the isolation plate is provided inside the air layer. The reinforcing plate is arranged horizontally, and reinforcing ribs are connected between the upper surface of the reinforcing plate and the inner top surface of the isolation plate.

[0029] In the aforementioned construction method of a circumferential road synchronously sinking elevated bridge pier, the construction platform includes a number of sub-platforms arranged around the circumference of the pier formwork, each sub-platform includes a pair of connecting parts connected to the main beam of the pier formwork, a slot is provided on the outer side of the connecting part, a triangular bracket is inserted into the slot and connected, and a support platform is erected between the pair of triangular brackets.

[0030] The present invention abandons the traditional external scaffolding type construction platform, and does not set up a separate scaffolding between the construction platform and the corresponding ground below it. The overall structure is a support-free structure, which consumes less steel, greatly saves manpower and material resources, and does not occupy the corresponding ground space below the construction platform. Specifically, considering that the templates of the pier columns all have main beams, the present invention designs a pair of connectors connected to the main beams, and the outer side of the connector of the invention is provided with a slot for a triangular bracket. When the triangular bracket is inserted, it is only necessary to fix the support platform above it, and the sub-platform on one side is completed. According to the position of the main beam on the pier column template, multiple sub-platforms can be built to surround the template to realize the construction platform. A large number of steel pipes used for scaffolding can be saved. The entire erection process is relatively convenient, including the later disassembly and assembly. The components after disassembly and assembly can be reused, which greatly improves the erection speed and reduces costs.

[0031] In the aforementioned construction method for a circumferential road synchronously sinking elevated bridge pier, the connecting member body is C-shaped and is sleeved on the outer periphery of the main beam of the pier formwork.

[0032] In the aforementioned construction method of a circumferential road synchronously sinking elevated bridge pier, the triangular bracket includes a first leg perpendicular to the horizontal plane and a second leg perpendicular to the first leg. The first leg and the second leg are fixedly connected via a third leg. The lower end of the first leg is inserted into the slot, and the support platform is placed above the second leg.

[0033] In the aforementioned construction method of a circumferential road synchronously sinking elevated bridge pier, the slot and the triangular bracket are fixedly connected by bolts, one end of the bolt passes through the first leg and the slot and extends to the outside of the slot, and the other end of the bolt passes through the connecting piece and the main beam and extends to the outside of the connecting piece.

[0034] In the aforementioned construction method of a circumferential road synchronously sinking elevated bridge pier, the top height of the first leg is higher than the setting height of the second leg, the lower bottom surface of the support platform abuts the second leg, and the side surface of the support platform abuts the first leg and is connected to the first leg.

[0035] In the aforementioned construction method of a circumferential road synchronously sinking elevated bridge pier, the opening of the slot faces upward, and the inner wall of the slot is provided with a plurality of first protrusions; a plurality of second protrusions are provided on the side of the first leg opposite to the plurality of first protrusions; after the first leg is inserted into the slot, the plurality of first protrusions and the plurality of second protrusions are arranged alternately from top to bottom.

[0036] In the aforementioned construction method for a circumferential road synchronously sinking elevated bridge pier, the first convexity and the second convexity are both hemispherical in shape, and the spherical radius of the first convexity is smaller than the spherical radius of the second convexity.

[0037] In the aforementioned construction method of a circumferential road synchronously sinking elevated bridge pier, a gasket is sandwiched between the side surfaces of the first legs on the opposite sides of the second protrusions and the inner wall of the slot, and the thickness of the gasket is greater than the spherical radius of the first protrusion.

[0038] In the aforementioned construction method for a circumferential road synchronously sinking elevated bridge pier, the height of the gasket is greater than the depth of the slot.

[0039] In the aforementioned construction method for circumferential road synchronously sinking elevated bridge piers, a safety guardrail is installed on the support platform. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of the positional relationship between the side baffles, pier columns and caps of the present invention;

[0041] Figure 2 It is a structural diagram of the side baffle;

[0042] Figure 3 This is a schematic diagram of the installation process of the side baffle;

[0043] Figure 4 This is a schematic diagram of the road structure around the platform;

[0044] Figure 5 yes Figure 4 A local enlarged view at point A;

[0045] Figure 6 It is a schematic structural diagram of a single sub-platform of the present invention;

[0046] Figure 7 It is a schematic diagram of the connection position relationship between a pair of connectors and the main beam;

[0047] Figure 8 It is a schematic diagram of the connection structure between the connector, the main beam and the first leg;

[0048] Figure 9 yes Figure 8A partial enlarged view at point B;

[0049] Figure 10 is based on Figure 5 A derivative structure of .

[0050] Figure 1: 1-side baffle, 2-isolation layer, 3-cap, 4-pier, 50-air fault structure, 61-sub-platform, 62-main beam, 63-connector, 64-slot, 65-triangular bracket, 66-support platform, 67-gasket, 68-safety guardrail, 101-baffle body, 102-support plate, 103-anchor bar, 301-blind hole, 401-original soil layer, 402-first steel wire grid, 403-first pond slag layer, 404-second steel wire grid, 405-second pond slag layer, 406- Graded gravel layer, 407-cement stabilized gravel lower base, 408-cement stabilized gravel upper base, 409-asphalt pavement layer, 410-fine stone concrete, 411-road curbstone, 412-road flat stone, 413-planting soil, 414-gap layer, 501-isolation board, 502-air layer, 503-reinforcement board, 504-reinforcement rib, 505-wedge strip, 641-first protrusion, 651-first support leg, 652-second support leg, 653-third support leg, 6511-second protrusion, 1011-lifting ear. DETAILED DESCRIPTION

[0051] The present invention will be further described below with reference to the accompanying drawings and examples, but they are not intended to limit the present invention.

[0052] Embodiment: A construction method for a circumferential road synchronously sinking elevated bridge pier, comprising forming a cap 3, forming a pier 4 and paving a circumferential road of the cap 3.

[0053] The formation of the cap 3 includes excavating the foundation pit, installing the steel frame of the cap 3, installing the formwork of the cap 3, pouring the concrete of the cap 3 and removing the formwork of the cap 3; retaining the original soil of the foundation pit when excavating the foundation pit;

[0054] Among them, the length, width and height of the foundation pit need to be set to ensure that there is enough space inside the foundation pit to install the steel frame of the pedestal 3 and the template of the pedestal 3. After the pedestal 3 is formed, there should still be enough gap around the pedestal 3 inside the foundation pit for the subsequent installation of the isolation layer 2.

[0055] Pier column forming includes pier column formwork installation, construction platform installation, pier column concrete pouring and pier column formwork removal;

[0056] Among them, the construction platform adopts a support-free structural construction platform.

[0057] Paving of the road around the platform 3 includes installation of side panels 1, backfilling of foundation pit with original soil, backfilling of pond residue, paving of graded crushed stones, paving of cement base and paving of asphalt pavement;

[0058] The installation of the side baffle 1 includes: installing the side baffles 1 perpendicular to the top surface of the pedestal 3 on both sides of the top surface of the pedestal 3 close to the road, aligning the outer side of the side baffle 1 with the side surface of the pedestal 3, and setting an isolation layer 2 on the outer side of the side baffle 1 and the side surface of the pedestal 3. The top view position relationship between the side baffle 1 and the pier 4 and the pedestal 3 can be referred to. Figure 1 ;

[0059] The backfilling of the original soil of the foundation pit includes: filling the original soil of the foundation pit into the gaps around the foundation pile 3 in the foundation pit, so that the original soil of the foundation pit in the gaps is backfilled to the same height as the original soil layer 401 before the foundation pit is excavated.

[0060] Admittedly, the construction of an elevated bridge involves numerous steps, and the present invention only introduces the forming of the cap 3 , the forming of the pier 4 , and the paving of the road around the cap 3 .

[0061] As a preference, the side baffle 1 is in a C-shape as a whole. For the specific structure, please refer to Figure 2 , arranged along the edge of the top surface of the pedestal 3, the side baffle 1 includes a baffle body 101, and support plates 102 perpendicular to the baffle body 101 are respectively provided on both sides of the baffle body 101; the support plate 102 is pre-embedded with anchor bars 103, and the top surface of the pedestal 3 is provided with a blind hole 301 for inserting the anchor bars 103, and the blind hole 301 is a 40mm drilled hole.

[0062] Preferably, the diameter of the anchor bar 103 is 25 mm, and the positioning of the embedded anchor bar 103 must be accurate to within 3 mm.

[0063] The present invention adopts the method of planting anchor bars 103 only at the support plates 102 at both ends of the lateral direction instead of planting anchor bars 103 on the entire cross section. This is mainly because the maximum bending moment of the baffle body 101 is close to the pier column, and the pier column 4 and the lateral support plates 102 can be used to form three support points to withstand the extrusion force in the driving direction, which can reduce the number of planted bars.

[0064] Preferably, the side baffle 1 can be prefabricated. Using prefabrication assembly technology can save construction costs, control the quality of the finished product, ensure the flatness of the production surface, and save construction time. Therefore, the inner side and top surface of the baffle body 101 are provided with lugs 1011. The lugs 1011 are made of round steel with a diameter of 20 mm to facilitate the movement of the prefabricated side baffle 1. Specifically, the prefabrication of the side baffle 1 includes the following steps:

[0065] a1. Build a steel frame according to the shape of the side guard plate 1 and pre-embed the anchor bars 103;

[0066] a2. Build several templates around the steel frame of the side baffle 1 according to the shape of the side baffle 1. The template located outside the baffle body 101 is made of PTFE sheet, and the remaining templates are made of wood templates. The thickness of the wood template is 15 mm, and the thickness of the PTFE sheet is 1 mm.

[0067] a3. Pour concrete and form side baffle 1 after the concrete solidifies;

[0068] a4. Remove all wooden formwork connected to the side baffle 1, and retain the PTFE plate connected to the side baffle 1. The side baffle 1 is prefabricated, and the PTFE plate (polytetrafluoroethylene plate) is used as the bottom mold and also as the isolation layer 2. The PTFE plate has the advantages of high lubrication and non-adhesion, which can effectively reduce the side friction resistance of the base 3. At the same time, the 1mm thick PTFE plate is also relatively light and economical.

[0069] Preferably, after the prefabricated side dam 1 is cured on-site to the designed strength, it is transported to the construction site by a trailer for installation. The installation of the side dam 1 includes the following steps:

[0070] Before installation, clean the top surface of the platform 3, mark out the blind hole 301, and drill a blind hole 301 with a diameter of 40mm as a rebar hole. The drilling depth should be no less than 64cm.

[0071] After drilling, blow away the powder in the hole and clean the floating slurry on the surface of the base 3 in contact with the side baffle 1 to ensure that the planting reinforcement and the seating slurry can be effectively bonded;

[0072] b1. Pour rebar glue into all blind holes 301 on the top surface of the cap 3, and spread a layer of support grouting material with a thickness of not less than 5 mm on the surface of the cap 3 in contact with the side baffle 1;

[0073] b2. Take the prefabricated side baffle 1, align the pre-buried anchor bar 103 of the side baffle 1 with the blind hole 301 and insert it. The schematic diagram of this state can be referred to Figure 3 , until the bottom surface of the side baffle 1 is fitted with the top surface of the platform 3, the amount of the anchor glue in step b1 satisfies: at the moment before the bottom surface of the side baffle 1 is fitted with the top surface of the platform 3, the anchor glue overflows from the blind hole 301;

[0074] b3. After the rebar-anchoring glue solidifies, clean the side of the pedestal 3 corresponding to the bottom of the side baffle 1 (if the side of the pedestal 3 is covered by the original soil of the foundation pit, it is necessary to dig down to a certain depth to ensure that the side of the pedestal 3 is completely exposed, and rinse off the attachments on the side of the pedestal 3, and use mortar to repair the damaged or uneven surface), and then use cement nails or nail-free glue to fix the PTFE plate on the entire side of the pedestal 3, so that the PTFE plate fixed on the side of the pedestal 3 and the PTFE plate on the outside of the side baffle 1 are connected to form a whole with only one seam. The two spliced ​​PTFE plates serve as the isolation layer 2 for the transition between the pedestal 3 and the road.

[0075] The prefabricated assembled side baffle 1 is manufactured in advance at a designated location, and standardized manufacturing and maintenance are completed at the designated location. Compared with a site with more uncertain factors, the quality is much more stable, thereby improving the overall project quality.

[0076] The construction period of cast-in-place side baffles on both sides of a pedestal is about 3 to 4 days, and after completion, they need to be cured to the design strength before entering the next process. The on-site installation time of prefabricated assembled side baffles is about 2 to 3 pedestals per day, and they can enter the next process after installation, which has greater construction period benefits.

[0077] As a preferred method, the road structure outside the platform 3 can refer to Figure 4 and Figure 5 , including an original soil layer 401 at the bottom layer, a first steel wire grid 402 is laid on the top surface of the original soil layer 401, a first pond slag layer 403 is laid above the first steel wire grid 402, a second steel wire grid 404 is laid on the top surface of the first pond slag layer 403, a second pond slag layer 405 is laid above the second steel wire grid 404, and above the second pond slag layer 405 are sequentially provided with a graded gravel layer 406, a cement stabilized gravel lower base layer 407, a cement stabilized gravel upper base layer 408 and an asphalt pavement layer 409.

[0078] The first steel wire grid 402 and the second steel wire grid 404 of the present invention are completely isolated from the side surface of the platform 3 under the isolation of the isolation layer 2.

[0079] In this road structure, a key link is to fill the gaps around the foundation pedestal 3 in the foundation pit with original soil, so that it is flush with the original soil on the outside, forming a complete layer of original soil 401 on the outside of the foundation pedestal 3.

[0080] Preferably, the pedestal 3 and the side baffle 1 are completely isolated from the road side structure by the isolation layer 2. The top surface of the side baffle 1 is flush with the top surface of the cement-stabilized gravel subbase 407. Fine stone concrete 410 is provided on the top surface of the cement-stabilized gravel subbase 407 near one end of the side baffle 1. Mutually perpendicular road curb stones 411 and road flat stones 412 are embedded in the top of the fine stone concrete 410. The top surface of the road flat stone 412 is flush with the top surface of the asphalt pavement layer 409. The inner side of the side baffle 1 and the fine stone concrete 410 are filled with planting soil 413.

[0081] Here, installing the prefabricated assembled side baffle 1 can reduce the damage of the road curb 411 and the road flat stone 412, and reduce the future project repair costs.

[0082] Preferably, the isolation layer 2 is separated from the first pond slag layer 403 and the second pond slag layer 405 by an air fault structure 50. The air fault structure 50 includes a C-shaped isolation plate 501. The C-shaped opening of the isolation plate 501 is against the outer side surface of the isolation layer 2, so that the isolation layer 2 and the isolation plate 501 cooperate to form a closed air layer 502; the bottom of the isolation plate 501 is fixedly connected to the first steel wire grid 402, and the outer side wall of the isolation plate 501 is fixedly connected to the second steel wire grid 404.

[0083] In actual applications, due to the different sinking amplitudes on the road side and the side of the pedestal 3, there will inevitably be friction between the road side structure and the isolation layer 2. Even if a polytetrafluoroethylene plate with a very small friction coefficient is used as the material of the isolation layer 2, the friction between the road side structure and the isolation layer 2 cannot be ignored. There will still be a small bulge at the transition between the pedestal 3 and the road. The design of the air fault structure 50 helps to reduce the friction between the road side structure and the isolation layer 2 and reduce the degree of bulging.

[0084] As the main component of the air fault structure 50, the isolation plate 501 not only cooperates with the isolation layer 2 to form a closed air layer 502, but also serves as a positioning reference for the setting position of the end of the first steel wire grid 402 and the second steel wire grid 404, thereby connecting the end of the first steel wire grid 402 and the second steel wire grid 404.

[0085] Preferably, a gap layer 414 is provided between the top of the isolation plate 501 and the graded gravel layer 406, and the gap layer 414 is filled with gravel; the graded gravel layer 406 is filled with graded gravel, and the graded gravel particle size of the graded gravel filled in the graded gravel layer 406 gradually decreases from far to near the isolation layer 2.

[0086] As mentioned above, in actual application, the friction between the road side structure and the isolation layer 2 cannot be ignored, so it is inevitable that the road settlement at the far isolation layer 2 will be greater than the road at the near isolation layer 2. This is why the present invention still produces small bulges, but the gap layer 414 and the gravel filled in the gap layer 414 help to alleviate the bulge. The reason is as follows: when the road settlement at the far isolation layer 2 is greater than the road at the near isolation layer 2, since the outer wall of the isolation plate 501 is fixedly connected to the second steel wire grid 404, the second steel wire grid 404 will give the isolation plate 501 a downward pulling force. Figure 4In the view, the second steel wire grid 404 applies a pulling force obliquely to the lower right to the isolation plate 501, which will cause the upper end of the isolation plate 501 to break away from the contact with the isolation layer 2. The closed air layer 502 formed by the isolation layer 2 and the isolation plate 501 is opened, and the gravel filled in the gap layer 414 gradually enters the air layer 502, thereby promoting the sinking of the road above the gap layer 414, and using this sinking amount to compensate for the problem of the slower road near the isolation layer 2. Of course, the sand and gravel falling from the gap layer 414 will be supplemented by the graded gravel falling from the graded gravel layer 406. The graded gravel particle size of the graded gravel filled in the graded gravel layer 406 gradually decreases from far to near the isolation layer 2, which is conducive to the graded gravel falling and supplementing the gap layer 414. In other words, the graded gravel at the far isolation layer 2 will also slowly be supplemented to the near isolation layer 2, giving certain support to the road above the gap layer 414, and avoiding the road above the gap layer 414 from collapsing due to the upper end of the isolation plate 501 detaching from the isolation layer 2.

[0087] Preferably, the fixed connection position of the second steel wire grid 404 on the outer wall of the isolation plate 501 is higher than the center position of the isolation plate 501. When the second steel wire grid 404 applies a pulling force obliquely to the lower right to the isolation plate 501, the upper end of the isolation plate 501 is more likely to break away from contact with the isolation layer 2.

[0088] Preferably, a reinforcing plate 503 connected to the inner wall of the isolation plate 501 is provided inside the air layer 502. The reinforcing plate 503 is arranged horizontally, and a reinforcing rib 504 is connected between the upper surface of the reinforcing plate 503 and the inner top surface of the isolation plate 501. The design of the reinforcing rib 504 enables the top of the isolation plate 501 to obtain a certain support, thereby preventing the isolation plate 501 from collapsing itself, and has the effect of alleviating the deformation of the isolation plate 501.

[0089] In addition, reference Figure 10 , Figure 10 for Figure 5 A derivative structure based on this idea can be seen in Figure 10 In the structure, the upper end of the C-shaped opening of the isolation plate 501 is not close to the isolation layer 2, but a wedge-shaped strip 505 is provided between the upper end of the C-shaped opening of the isolation plate 501 and the isolation layer 2. It can be seen from the cross section of the wedge strip 505 that it is matched with the upper end of the C-shaped opening of the isolation plate 501 through an inclined surface. The advantage of this structure is that when the road structure is in the early stage of uneven settlement, the second steel wire grid 404 gives the isolation plate 501 an oblique downward pulling force. At this time, gravel will not immediately enter the air layer 502 (or the amount of gravel entering is small). Instead, the wedge strip 505 itself sinks relative to the isolation plate 501 to make up for the gap that may be generated between the isolation layer 2 and the road side. In the middle and late stages of uneven settlement of the road structure, the wedge strip 505 will fall completely into the air layer 502. Thereafter, the effect of the isolation plate 501 is equivalent to Figure 5 The structure is not described in detail here.

[0090] The isolation layer 2 of the present invention adopts a 1mm polytetrafluoroethylene board, which is considered from the cost aspect. If the cost is not considered, the polytetrafluoroethylene board is designed to have a structure with a thickness gradually becoming thinner from top to bottom. At this time, the polytetrafluoroethylene board can give the outer road a downward oblique reaction force, and the synchronous settlement effect of the road outside the platform 3 will be better.

[0091] The circumferential road paving of the platform 3 of the present invention specifically includes the following steps:

[0092] c1. First, fill the gaps around the foundation pedestal 3 in the foundation pit with the original soil until it is flush with the original soil outside, forming a complete original soil layer 401 outside the isolation layer 2;

[0093] c2. Lay a first steel wire grid 402 on the original soil layer 401 so that the end of the first steel wire grid 402 abuts against the isolation layer 2;

[0094] c3. Take the prefabricated isolation plate 501, place the lower end of the isolation plate 501 against the first steel grid 402, and weld it to the first steel grid 402, so that the C-shaped open end of the isolation plate 501 is against the outer side of the isolation layer 2, thereby forming a closed air layer 502;

[0095] c4. Filling pond slag above the first steel wire grid 402 to form a first pond slag layer 403;

[0096] c5. Lay a second steel wire grid 404 on the first pond slag layer 403, with the ends of the second steel wire grid 404 resting against the outer side of the isolation plate 501 and welding the ends thereto;

[0097] c6. Fill pond slag above the second steel wire grid 404 to form a second pond slag layer 405, ensuring that a gap layer 414 is reserved between the end of the second pond slag layer 405 and the isolation layer 2. In actual operation, a baffle can be erected above the isolation plate 501 when filling the second pond slag layer 405;

[0098] c7. Fill the gap layer 414 with gravel, with the gravel filling height being level with the top surface of the second pond slag layer 405;

[0099] c8. Laying graded crushed stones on the second pond slag layer 405 to form a graded crushed stone layer 406, ensuring that the graded crushed stones gradually decrease in size from far to near the isolation layer 2;

[0100] c9. Pour a layer of cement on the graded gravel layer 406 to stabilize the graded gravel below, forming a cement-stabilized gravel base layer 407;

[0101] c10. Fine stone concrete 410 is set on the upper surface of the cement-stabilized crushed stone base layer 407 near one end of the side baffle 1, and a road curb 411 and a road flat stone 412 are embedded perpendicular to each other on the top of the fine stone concrete 410;

[0102] c11. Using the fine stone concrete 410 as the boundary, pour another layer of cement on top of the cement-stabilized gravel lower base 407 to form the cement-stabilized gravel upper base 408;

[0103] c12. Fill the planting soil 413 above the base 3 inside the side baffle 1 and the fine stone concrete 410;

[0104] c13. Using the fine stone concrete 410 as the boundary, lay asphalt on top of the cement-stabilized crushed stone upper base 408 to form an asphalt pavement layer 409, ensuring that the top surface of the asphalt pavement layer 409 is flush with the top surface of the road flat stone 412.

[0105] The circumferential road paving of the cap 3 of the present invention can also be used to renovate the bulging parts of the existing urban elevated cap 3, alleviate the bulging problem of the road around the elevated cap 3, and improve driving comfort.

[0106] As a preference, the construction platform structure of the present invention is as follows Figures 6 to 9 As shown, it includes several sub-platforms 61 arranged around the circumference of the pier column formwork, each sub-platform 61 includes a pair of connecting parts 63 connected to the main beam 62 of the pier column formwork, a slot 64 is provided on the outer side of the connecting part 63, a triangular bracket 65 is inserted into the slot 64, and a support platform 66 is set between the pair of triangular brackets 65.

[0107] Preferably, the number of sub-platforms 61 is 4. When the 4 sub-platforms 61 are constructed, the overall construction platform is square.

[0108] The construction platform of the present invention generally needs to be used in conjunction with a ladder cage, wherein the ladder cage can be moved to a position close to a sub-platform 61 on one side of the construction platform. When the entire construction platform is erected, construction workers can climb up to the construction platform along the ladder cage.

[0109] Preferably, the main body of the connector 63 is C-shaped and is mounted on the outer periphery of the main beam 62 of the pier formwork. The connector 63 is inserted from the end of the main beam 62. The C-shape ensures that at least three inner sides of the connector 63 can be in contact and connected with the main beam 62, thereby ensuring the connection strength. The C-shaped opening of the connector 63 can be set smaller to allow bolts to pass through. In this way, the connector 63 can have four inner sides that can be in contact and connected with the main beam 62, thereby further improving the connection strength.

[0110] Preferably, the triangular bracket 65 includes a first leg 651 perpendicular to the horizontal plane and a second leg 652 perpendicular to the first leg 651. The first leg 651 and the second leg 652 are fixedly connected via a third leg 653. The lower end of the first leg 651 is inserted into the slot 64, and the support platform 66 is placed above the second leg 652. The three legs have high stability.

[0111] Preferably, the slot 64 and the triangular bracket 65 are fixedly connected by bolts, one end of the bolt passes through the first leg 651 and the slot 64 and extends to the outside of the slot 64, and the other end of the bolt passes through the connecting piece 63 and the main beam 62 and extends to the outside of the connecting piece 63, further ensuring the connection strength between the connecting piece 63 and the main beam 62 and the first leg 651, thereby improving safety.

[0112] Preferably, the top height of the first leg 651 is higher than the setting height of the second leg 652, the lower bottom surface of the support platform 66 is against the second leg 652, and the side surface of the support platform 66 is against the first leg 651 and connected to the first leg 651, which facilitates the installation of the support platform 66 and can be precisely limited.

[0113] Preferably, the opening of the slot 64 faces upward, and a plurality of first protrusions 641 are provided on the inner wall of the slot 64; a plurality of second protrusions 6511 are provided on the side of the first leg 651 opposite to the plurality of first protrusions 641; after the first leg 651 is inserted into the slot 64, the plurality of first protrusions 641 and the plurality of second protrusions 6511 are arranged alternately from top to bottom. When the first leg 651 is inserted into the slot 64, the plurality of first protrusions 641 and the plurality of second protrusions 6511 can limit each other in the vertical direction, which can effectively prevent the triangular bracket 65 from being pulled outward, thereby improving safety.

[0114] Preferably, the first protrusion 641 and the second protrusion 6511 are both hemispherical in shape, and the spherical radius of the first protrusion 641 is smaller than the spherical radius of the second protrusion 6511. Due to the existence of the first protrusion 641 and the second protrusion 6511, when the first leg 651 is inserted into the slot 64, the smooth side wall of the first leg 651 (the opposite side of the second protrusion 6511) needs to be close to the smooth side wall of the slot 64 (the opposite side of the first protrusion 641), and the spherical radius of the first protrusion 641 is smaller than the spherical radius of the second protrusion 6511, which can ensure that the first leg 651 is smoothly inserted.

[0115] Preferably, a gasket 67 is sandwiched between the side surface of the first leg 651 on the opposite side of the several second protrusions 6511 and the inner wall of the slot 64. The thickness of the gasket 67 is greater than the spherical radius of the first protrusion 641. After the first leg 651 is successfully inserted into the slot 64, the triangular bracket 65 is pushed horizontally along the direction of the first protrusion 641, so that a mutual limiting relationship is formed between the several first protrusions 641 and the several second protrusions 6511 in the vertical direction. At this time, a gap will be left between the smooth side wall of the first leg 651 and the smooth side wall of the slot 64. The insertion of the gasket 67 into the gap can improve the stability of the installation of the triangular bracket 65.

[0116] Preferably, the height of the gasket 67 is greater than the depth of the slot 64 to facilitate the insertion and removal of the gasket 67.

[0117] Preferably, a safety guardrail 68 is installed on the support platform 66 to improve safety.

[0118] The installation process of the construction platform of the present invention is as follows: first, take a pair of connecting parts 63 and insert them along the two ends of the main beam 62; then, insert a triangular bracket 65 into each of the slots 64 of the pair of connecting parts 63, and tighten the triangular bracket 65 with bolts after insertion; then, set up a support platform 66 on the second legs 652 of the pair of triangular brackets 65, and the support platform 66 rests on the first leg 651 and is fastened to the first leg 651 with bolts; then, complete the installation of the safety guardrail 68 on the support platform 66, and a sub-platform 61 is built; repeat the above building steps to complete the construction of 4 sub-platforms 61 to form an integrated construction platform.

[0119] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0120] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions based on the principles of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A construction method for circumferential road synchronously subsidence type viaduct piers, characterized by: Including the formation of the foundation, the formation of the pier and the paving of the road around the foundation; The said cap forming includes excavating a foundation pit, installing a steel frame of the cap, installing a cap formwork, pouring concrete for the cap and removing the cap formwork; retaining the original soil of the foundation pit when excavating the foundation pit; The pier column forming includes the installation of pier column formwork, the installation of construction platform, the pouring of pier column concrete and the removal of pier column formwork; The paving of the road around the platform includes the installation of side baffles, backfilling of original soil in the foundation pit, backfilling of pond residue, paving of graded crushed stones, paving of cement base and paving of asphalt pavement; The side baffle installation includes: installing side baffles perpendicular to the top surface of the platform on both sides of the top surface of the platform close to the road, aligning the outer sides of the side baffles with the side surfaces of the platform, and providing an isolation layer between the outer sides of the side baffles and the side surfaces of the platform; The backfilling of the foundation pit includes: filling the foundation pit with original soil in the gap around the foundation pit, so that the height of the foundation pit original soil at the gap is backfilled to the same height as the original soil layer before the foundation pit is excavated; The road outside the cap includes an original soil layer at the bottom, a first steel wire grid is laid on the top surface of the original soil layer, a first pond slag layer is laid above the first steel wire grid, a second steel wire grid is laid on the top surface of the first pond slag layer, a second pond slag layer is laid above the second steel wire grid, and a graded crushed stone layer, a cement stabilized crushed stone lower base, a cement stabilized crushed stone upper base and an asphalt pavement layer are sequentially laid above the second pond slag layer; The isolation layer is separated from the first pond slag layer and the second pond slag layer by an air fault structure. The air fault structure includes a C-shaped isolation plate. The C-shaped opening of the isolation plate is against the outer side of the isolation layer, so that the isolation layer and the isolation plate cooperate to form a closed air layer; the bottom of the isolation plate is fixedly connected to the first steel wire grid, and the outer side wall of the isolation plate is fixedly connected to the second steel wire grid.

2. The method for constructing a circumferential road synchronously sinking elevated bridge pier according to claim 1, characterized in that: The side baffle is C-shaped as a whole and is arranged along the edge of the top surface of the pedestal. The side baffle includes a baffle body, and support plates perpendicular to the baffle body are respectively provided on both sides of the baffle body; the support plate is pre-embedded with anchor bars, and the top surface of the pedestal is provided with blind holes for inserting the anchor bars.

3. The method for constructing piers of a circumferential road synchronously sinking elevated bridge according to claim 2, characterized in that: The production of the side baffle comprises the following steps: a1. Build a steel frame according to the shape of the side panels and embed anchor bars in advance; a2. Build several templates around the steel frame of the side baffle according to the shape of the side baffle. The templates outside the baffle body are made of PTFE sheets, and the rest are made of wood. a3. Pour concrete and form side baffles after the concrete solidifies; a4. Remove all wooden formwork connected to the side baffles, retain the Teflon plates connected to the side baffles, and the side baffles are prefabricated.

4. The method for constructing piers of a circumferential road synchronously sinking elevated bridge according to claim 3, characterized in that: The installation of the side guard comprises the following steps: b1. Pour rebar glue into all blind holes on the top surface of the bearing platform; b2. Take the prefabricated side baffles, align the pre-embedded anchor bars of the side baffles with the blind holes, and insert them until the bottom surface of the side baffles is in contact with the top surface of the pedestal. The amount of anchor glue used in step b1 is sufficient to ensure that the anchor glue overflows from the blind holes immediately before the bottom surface of the side baffles is in contact with the top surface of the pedestal. b3. Clean the side of the pedestal corresponding to the side baffle, and use cement nails or nail-free glue to fix the PTFE plate on the entire side of the pedestal, so that the PTFE plate fixed on the side of the pedestal and the PTFE plate on the outside of the side baffle are connected to form a whole with only one seam. The two spliced ​​PTFE plates serve as an isolation layer for the transition between the pedestal and the road.

5. The construction method of a circumferential road synchronously sinking elevated bridge pier according to claim 1, characterized in that: The pedestal and side baffles are completely isolated from the road by an isolation layer. The top surface of the side baffles is level with the top surface of the cement-stabilized gravel lower base layer. Fine stone concrete is provided on one end of the top surface of the cement-stabilized gravel lower base layer near the side baffles. Road curbs and road flat stones that are perpendicular to each other are embedded in the top of the fine stone concrete. The top surface of the road flat stones is level with the top surface of the asphalt pavement layer. Planting soil is filled on the inside of the side baffles and fine stone concrete.

6. The method for constructing piers of a circumferential road synchronously sinking elevated bridge according to claim 1, characterized in that: A gap layer is provided between the top of the isolation plate and the graded crushed stone layer, and the gap layer is filled with sand and gravel; the graded crushed stone layer is filled with graded crushed stone, and the particle size of the graded crushed stone filled in the graded crushed stone layer gradually decreases from far to near the isolation layer.

7. The method for constructing piers of a circumferential road synchronously sinking elevated bridge according to claim 1, characterized in that: A reinforcing plate connected to the inner side wall of the isolation plate is provided inside the air layer. The reinforcing plate is arranged horizontally, and reinforcing ribs are connected between the upper surface of the reinforcing plate and the inner top surface of the isolation plate.

8. The method for constructing piers of a circumferential road synchronously sinking elevated bridge according to claim 1, characterized in that: The construction platform includes several sub-platforms arranged around the pier column formwork, each sub-platform includes a pair of connecting parts connected to the main beam of the pier column formwork, a slot is provided on the outer side of the connecting part, a triangular bracket is inserted into the slot and connected, and a support platform is set up between the pair of triangular brackets.

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