Assembly type large cantilever cap beam construction method

Abstract

The present application relates to the technical field of concrete cap beam, especially to a kind of assembly type large cantilever cap beam construction method.Different from the traditional cap beam construction method, the construction method described in the application is divided into construction preparation, measurement lofting, load support installation, pier top chiseling, cap beam reinforcement and prestressed pipe installation, formwork installation, concrete pouring and maintenance, loading preloading, tensioning prestress and support formwork removal.Assembly type installation method and connection assembly process are completed on the ground, which shortens the construction period, ensures the safety of the construction process and improves the construction efficiency.In addition, the construction method described in the application has small land area and convenient ground traffic, which is more conducive to the construction site.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete cap beam, in particular to a fabricated large cantilever cap beam construction method. BACKGROUND

[0002] Cap beam refers to the cross beam arranged on the top of bent pile pier for supporting, distributing and transferring the load of the upper structure, also known as cap beam, the cross beam of reinforced concrete or low-reinforced concrete arranged on the bridge pier or bent pile, which mainly supports the upper structure of the bridge and transfers all the load to the lower structure, and some bridges directly connect the cap beam with the bent pile, and some bridges connect the cap beam with the stand column after the bent pile.

[0003] At present, land resources are scarce, the traditional cap beam construction occupies a large area of land, and the ground transportation is not convenient, so it is more and more necessary to shorten the construction period of the cap beam and reduce the land occupation.

[0004] Chinese patent CN113089501A discloses a large cantilever concrete cap beam with few embedded parts and a fabricated bracket and its construction method, which comprises the following steps: step S1, core steel rod hole reservation, PVC pipe filled with sand and sealed during pier column pouring; step S2, core steel rod construction, the core steel rod is inserted into the reserved hole after the concrete reaches the design strength; triangular bracket installation is performed at the lower edge of the cantilever beam; upper layer steel bracket installation is performed at the lower edge of the cantilever beam; step S3, cantilever scaffold installation; bottom mold installation; steel bar binding; opposite-pulling precision rolled threaded steel installation, the opposite-pulling precision rolled threaded steel connects the opposite-pulling rods of the opposite-pulling formwork of the two pier columns inside the door-shaped support; step S4, vase section concrete pouring; cap beam steel bar, concrete construction, prestress construction; adjusting wire top, bracket layer-by-layer removal. It can be seen that the large cantilever concrete cap beam with few embedded parts and the fabricated bracket and its construction method have the following problems: long construction period, large construction land occupation, and inconvenient ground transportation. SUMMARY

[0005] Therefore, the present application provides a fabricated large cantilever cap beam construction method to solve the problems of large cap beam construction land occupation, inconvenient ground transportation, long construction period and large consumption of funds and construction materials in the prior art.

[0006] To achieve the above-mentioned purpose, the present application provides a fabricated large cantilever cap beam construction method. The fabricated large cantilever cap beam construction method comprises the following steps:

[0007] Step S1, construction preparation, reserving the required area of the construction site and determining the specific position of the concrete support according to the land occupation area and ground road traffic requirements required for the fabricated large cantilever cap beam construction;

[0008] Step S2, measurement lofting, a pressure detection device, a temperature monitoring device and a central control unit are arranged in the concrete support, after the concrete support is poured, before the construction of the cap beam, the construction personnel use the total station to perform cap beam edge line lofting; before the template is installed, the construction personnel loft to determine the template safe position and the concrete pouring height; before the concrete is poured, the construction personnel retest the cap beam upper axis;

[0009] Step S3, load-bearing support installation, the construction personnel use the control network to position and level the load-bearing support base point; first stage installation, install the unloading block and the column, connect the diagonal bracing channel steel and the diagonal bracing steel pipe on the ground, use the crane to hoist the connected channel steel and the diagonal bracing steel pipe to the corresponding position as a whole, connect the diagonal bracing and the steel column with the pin shaft and install symmetrically, and finally install the diagonal bracing steel pipe flat connection; second stage installation, the main cross beam is composed of three sections, after being assembled on the ground, the whole is hoisted by the crane, the cross beam is connected with the steel column, and then the diagonal bracing top pin shaft is installed; third stage installation, first, install the main cross beam flat connection, then install the distribution beam, the bottom mold frame, the template and the operation platform;

[0010] Step S4, pier top chiseling, the construction personnel use the air pick machine combined with manual work to chisel the pier top; the construction personnel mark the position after lofting the position of the pier top embedded in the cap beam; remove the concrete residue after chiseling;

[0011] Step S5, cap beam reinforcement and prestressed pipe installation, the construction personnel assemble the reinforcement cage, install the support cushion stone embedded reinforcement, and install the concrete cushion block at the bottom of the reinforcement cage, after the concrete cushion block installation is completed, the construction personnel hoist the reinforcement cage by the crane;

[0012] Step S6, install the template, pour the concrete into the cap beam, maintain the poured cap beam, load the cap beam with pre-pressure and tension the prestress, and finally remove the support template.

[0013] Further, in the load-bearing support installation process, the central control unit compares the pressure F0 borne by the support detected by the pressure detection device with the preset pressure to detect whether the installation meets the construction standard, the central control unit is provided with a preset pressure Fi for the i-th stage, a first preset pressure difference △F1 and a second preset pressure difference △F2, wherein △F1 < △F2, i = 1, 2, 3,

[0014] If Fi = F0, the installation meets the construction standard;

[0015] If Fi ≠ F0, it is preliminarily determined that the installation does not meet the construction standard, the difference △F between Fi and F0 is calculated and compared with △F1 and △F2 respectively to determine whether the installation of the load-bearing support meets the construction standard, and it is set that △F = IF0-FI;

[0016] If △F≤△F1, the pressure error is within the allowable range, and the installation meets the construction standard;

[0017] If △F1<△F≤△F2, the central control unit determines that the pressure deviation is caused by improper connection and installation of the components, and the on-site construction personnel check and adjust the connection state of the components;

[0018] If △F2<△F, the central control unit determines that the installation does not meet the construction standard, and checks whether the qualified rate of the components installed in this stage meets the standard.

[0019] Further, when the pressure detection device measures △F2<△F, the central control unit checks whether the qualified rate of the components installed in this stage meets the standard and checks whether the components installed in this stage are qualified by comparing the difference △F0 between △F and △F2 with a preset qualified difference, where △F0=△F-△F2. The central control unit is provided with a preset qualified difference △F', a first preset qualified number N1 and a second preset qualified number N2, where N1

[0020] If △F0<△F', the central control unit determines that the components installed in this stage are qualified, and considers whether external pressure is applied due to special weather

[0021] If △F0≥△F', the central control unit determines that the components installed in this stage are unqualified, and checks and counts the number of qualified components in this stage to determine whether the qualified rate of this batch of components meets the standard. The central control unit records the number of qualified components in this stage as N.

[0022] If N

[0023] If N1≤N

[0024] If N≥N2, the qualified rate of this batch of components meets the standard.

[0025] Further, when △F1<△F≤△F2, the central control unit compares the first qualified difference △Fa with the second qualified difference △Fb to determine how the construction personnel adjust the connection and installation of the components, where △Fa=Ι△F-F1Ι and △Fb=Ι△F-F2Ι.

[0026] If 0<△Fa<△Fb, the construction personnel check and adjust the connection and installation angle of the components;

[0027] If △Fa≥△Fb, the construction personnel need to disassemble and re-connect the components.

[0028] Further, the central control unit controls the external temperature T of the temperature detection device during the installation of the load-bearing support and adjusts Fi to a corresponding value according to the fluctuation value of T, the central control unit is provided with a first preset temperature T1, a second preset temperature T2, a first adjustment coefficient a1, a second adjustment coefficient a2, a third adjustment coefficient a3 and a fourth adjustment coefficient a4, wherein 0

[0029] If T≤0, the central control unit adjusts Fi to a first corresponding value Fia, and sets Fia=Fi×a1;

[0030] If 0

[0031] If T1

[0032] If T2

[0033] Further, the central control unit comprehensively judges whether a single component is qualified according to the comparison results of the ratio of the radius R of the reinforcing steel bar in the component to the preset radius and the ratio of the mass M of the reinforcing steel bar to the preset mass, the central control unit is provided with a first preset radius Ra, a second preset radius Rb, a first preset mass Ma and a second preset mass Mb, wherein Ra

[0034] If Ra≤R≤Rb and Ma≤M≤Mb, the central control unit determines that the component is qualified;

[0035] If R

[0036] Further, in the step S6, the metal bellows is used as a prestressed pipe and the steel strand is used as a prestressed steel beam. During the installation of the prestressed pipe, the metal bellows is first installed, the metal bellows is perpendicular to the anchor pad, after the installation of the metal bellows is completed, the steel strand is arranged in a horizontal bridge direction to pass through the steel strand to the metal bellows.

[0037] Further, in the step S6, the prestressed tensioning adopts a post-tensioning intelligent tensioning construction process, and simultaneously, the tensioning is performed in a left-right symmetrical sequence, the specific steps of the prestressed tensioning include:

[0038] Step S61. Tensioning to A% tensioning control tonnage

[0039] Step S62. Tensioning to B% tensioning control tonnage

[0040] Step S63. tensioning to C% tension control tonnage

[0041] Step S64. holding D minutes

[0042] Step S65. anchoring

[0043] Wherein, tensioning adopts tension force and elongation double control, mainly controls by tension force, and uses steel strand elongation value as a check standard.

[0044] Further, the loading pre-pressing adopts three-stage loading and one-stage unloading, gradually loads according to E%, F%, G% of the pre-pressing load, then unloads all the load, and symmetrically, uniformly and synchronously unloads during unloading.

[0045] Further, the concrete pouring adopts arm support pump pouring, and full-section layered pouring and layered vibrating of the concrete.

[0046] Compared with the prior art, the beneficial effects of the present application are that the fabricated large cantilever cap beam construction method uses less steel, the support lapping is simple, the installation period is short, the risk is small, the pier body hoop is adopted to form a wall connecting member of the cap beam bracket and the existing pier column, the overturning risk of the cap beam bracket in the installation and removal process is reduced, the top column top beam adopts a steel box beam structure, the steel material usage is reduced under the premise of meeting the structural stress, the steel structure assembly design concept speeds up the installation and removal progress of the cap beam bracket, the cap beam bracket and the construction access are shared, the ground traffic is not affected, and the cap beam construction efficiency is improved.

[0047] Further, the concrete support is provided with a pressure detection device for detecting the pressure borne by the support, the installation is detected whether to meet the construction standard through comparison of the detected pressure and the preset pressure, and the device is provided with a preset pressure Fi, a first preset pressure difference ΔF1 and a second preset pressure difference ΔF2, the range of the borne pressure is divided, it is ensured that each component is a qualified component, it is ensured that the components installed in each stage meet the construction standard, the construction quality is ensured, and the construction efficiency is improved.

[0048] Further, when ΔF2 < ΔF, whether the qualified rate of the components installed in the stage meets the standard is checked, whether the components installed in the stage are qualified is checked through comparison of the difference between ΔF and ΔF2 and the preset qualified difference, the preset qualified difference ΔF', the first preset qualified quantity N1 and the second preset qualified quantity N2 are provided, the process of detecting the components is more rapid and accurate, it is ensured that the components installed in each stage meet the construction standard, the construction quality is ensured, and the construction efficiency is improved.

[0049] Further, the prestressed pipeline installation selects a metal bellows pipe as a prestressed pipeline, the cap beam prestress adopts an intelligent tensioning process, prestressed steel strands are arranged in the transverse bridge direction, the prestressed steel strands all adopt steel strands, the metal bellows pipe is first installed, the metal bellows pipe is perpendicular to the anchor pad, after the metal bellows pipe is installed, the metal bellows pipe is penetrated by the steel strands, the installation of the prestress makes the structure not crack or crack later under normal use, thereby improving the safety of the construction process, ensuring the construction quality, and improving the construction efficiency.

[0050] Further, the support installation process is divided into three stages, the first stage installation: installing unloading blocks and columns, the inclined support channel steel is connected with the inclined support steel pipe on the ground, the connected channel steel and inclined support steel pipe are hoisted to the corresponding position as a whole by a crane, the inclined support is connected with the steel column by a pin shaft and is symmetrically installed, and finally, the inclined support steel pipe is connected horizontally; the second stage installation: the main cross beam is composed of three sections and is hoisted as a whole by a crane after being assembled on the ground, the cross beam is connected with the steel column, and the inclined support top pin shaft is installed; the third stage installation: finally, the horizontal connection between the main cross beams is installed; the distribution beam, the bottom mold frame, the formwork and the operation platform are installed; the installation process is carried out on the ground, the safety and efficiency of the construction are ensured, the construction quality is ensured, and the construction efficiency is improved.

[0051] Further, the concrete support is provided with a temperature detection device, Fi is adjusted to a corresponding value according to changes of external temperature, and first preset temperature T1, second preset temperature T2, first adjustment coefficient alpha 1, second adjustment coefficient alpha 2, third adjustment coefficient alpha 3 and fourth adjustment coefficient alpha 4 are arranged, so that errors caused by external environmental temperature when the pressure detection device detects pressure are reduced, the data measured by the pressure detection device is accurate, the construction quality is ensured, and the construction efficiency is improved.

[0052] Further, the concrete is maintained, surface stress caused by concrete shrinkage is reduced, the influence of different seasonal external temperatures on the concrete is adapted, the safety of the construction process is improved, the construction quality is ensured, and the construction efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 A program flow chart of the fabricated large cantilever cap beam construction method is described in the embodiments of the present application;

[0054] Figure 2 A flow chart of comparison between the pressure detected by the pressure detection device and the preset pressure is described in the embodiments of the present application;

[0055] Figure 3 A flow chart of judging whether a single component is qualified or not is described in the embodiments of the present application;

[0056] Figure 4The flow chart of adjusting the preset pressure to a corresponding value according to the external temperature is shown in the embodiment of the present application. DETAILED DESCRIPTION

[0057] In order to make the objects and advantages of the present application clearer, the present application will be further described in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0058] The preferred embodiments of the present application will be described below with reference to the accompanying drawings. It should be understood by those skilled in the art that the embodiments are only used to explain the technical principles of the present application and are not used to limit the protection scope of the present application.

[0059] It should be noted that, in the description of the present application, the terms of direction or position relationship such as "upper", "lower", "left", "right", "inner", "outer" and the like are based on the direction or position relationship shown in the drawings, which is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application.

[0060] In addition, it should also be noted that, in the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0061] Please refer to Figure 1 As shown in the figure, it is a program flow chart of the fabricated large cantilever cap beam construction method described in the embodiment of the present application, and the fabricated large cantilever cap beam construction method comprises:

[0062] Step S1, construction preparation, according to the land occupation area required by the fabricated large cantilever cap beam construction and the road traffic requirement, a site with the required area is reserved for the construction site and the specific position of the concrete support is determined;

[0063] Step S2, measurement and setting out, after the concrete support is poured, before the cap beam construction, the construction personnel set out the cap beam boundary line by using the total station; before the template is installed, the construction personnel set out the safe position of the template and the concrete pouring height; before the concrete is poured, the construction personnel re-measure the cap beam upper opening axis;

[0064] Step S3, load-bearing support installation, construction personnel use control network to position and level the load-bearing support base point; first stage installation: install unloading blocks and columns, connect the diagonal strut channel steel and diagonal strut steel pipe on the ground, use a crane to hoist the connected channel steel and diagonal strut steel pipe to the corresponding position, then connect the diagonal strut and steel column with a pin shaft and install symmetrically, and finally install the diagonal strut steel pipe flat link; second stage installation: the main cross beam is composed of three sections, which are hoisted by a crane after being assembled on the ground, the cross beam is connected with the steel column, and then the diagonal strut top pin shaft is installed; third stage installation: finally install the main cross beam flat link; install the distribution beam, bottom mold frame, formwork and work platform;

[0065] Step S4, pier top chiseling, construction personnel use a pneumatic pick machine combined with manual work to chisel the pier top; construction personnel mark the position of the pier top embedded cap beam before chiseling; remove the concrete residue after chiseling;

[0066] Step S5, cap beam reinforcement and prestressed pipe installation, construction personnel assemble the reinforcement cage, install the support pad stone embedded reinforcement, and install the concrete pad at the bottom of the reinforcement cage, then construction personnel hoist the reinforcement cage by a crane; the prestressed pipe adopts a metal bellows pipe, the cap beam prestress adopts an intelligent tensioning process, the prestress steel beam is arranged in the transverse bridge direction, and the prestress steel beam adopts a steel strand;

[0067] Step S6, formwork installation, concrete pouring and curing, preloading, prestress tensioning and support formwork removal.

[0068] Please refer to Figure 2 , which is a flowchart for comparing the detected pressure of the pressure detection device and the preset pressure, the concrete support is provided with a pressure detection device to detect the pressure F0 borne by the support, the comparison between the detected pressure and the preset pressure detects whether the installation meets the construction standard, and the device is provided with preset pressures Fi, i = 1, 2, 3, a first preset pressure difference △F1, a second preset pressure difference △F2, Fi is the preset pressure of the i-th stage, the preset pressure difference △F, △F = IF0-FI, wherein △F1 < △F2

[0069] Fi = F0, the installation meets the construction standard;

[0070] Fi ≠ F0, it is preliminarily determined that the installation does not meet the construction standard, and it is further determined whether the installation meets the construction standard by comparing △F with △F1 and △F2;

[0071] △F ≤ △F1, the pressure error is within the allowable range, and the installation meets the construction standard;

[0072] △F1 < △F ≤ △F2, it is determined that the pressure deviation is caused by improper connection and installation of components, and the on-site construction personnel check and adjust;

[0073] △F2<△F, it is determined that the installation does not meet the construction standard, and it is checked whether the qualified rate of the components installed in the stage meets the standard. It is ensured that the components installed in each stage meet the construction standard, the construction quality is ensured, and the construction efficiency is improved.

[0074] Specifically, when △F2<△F, it is checked whether the qualified rate of the components installed in the stage meets the standard, and it is checked whether the components installed in the stage are qualified by comparing the difference between △F and △F2 and the preset qualified difference, assuming that △F0=△F-△F2, the preset qualified difference △F', the first preset qualified number N1, and the second preset qualified number N2, wherein N1<N2,

[0075] △F0<△F', the components installed in the stage are qualified, and whether external pressure is applied due to special weather is considered

[0076] △F0≥△F', the components installed in the stage are not qualified

[0077] If the components installed in the stage are not qualified, the components in the stage are checked respectively, and the number of qualified components is recorded as N

[0078] N<N1, the qualified rate of the batch of components does not meet the standard

[0079] N1≤N<N2, most of the components are usable, and the qualified components with △F0<△F' are screened out

[0080] N≥N2, the qualified rate of the batch of components meets the standard. It is ensured that the components installed in each stage meet the construction standard, the construction quality is ensured, and the construction efficiency is improved.

[0081] Specifically, when △F1<△F≤△F2, the connection and installation of the components are checked and adjusted, assuming that the first preset qualified difference △Fa=|△F-F1| and the second preset qualified difference △Fb=|△F-F2|

[0082] 0<△Fa<△Fb, the connection of the components is fine-tuned

[0083] △Fa≥△Fb, the components need to be removed and reconnected and installed.

[0084] Please refer to Figure 3 which is a flowchart for judging whether a single component is qualified according to the embodiment of the application, and when detecting whether a single component is qualified, the results of comparing the radius R of the reinforcing steel in the component with the preset radius and the results of comparing the mass M with the preset mass are comprehensively judged, assuming that the first preset radius is Ra, the second preset radius is Rb, the first preset mass is Ma, and the second preset mass is Mb, wherein Ra<Rb and Ma<Mb,

[0085] Ra≤R≤Rb, the radius of the steel bar in the component is qualified

[0086] R<Ra or Rb<R, the radius of the steel bar in the component is unqualified

[0087] Ma≤M≤Mb, the mass of the steel bar in the component is qualified

[0088] M<Ma or Mb<M, the mass of the steel bar in the component is unqualified

[0089] If the radius and mass of the steel bar in the component are both qualified, the component is qualified, and if the radius and / or mass of the steel bar in the component are unqualified, the component is unqualified. It is ensured that the component installed at each stage meets the construction standard, the construction quality is ensured, and the construction efficiency is improved.

[0090] Please refer to Figure 4 , which is a flow chart for adjusting the preset pressure to a corresponding value according to the external temperature

[0091] The concrete support is provided with a temperature detection device, which adjusts Fi to a corresponding value according to the change of the external temperature T, and is provided with a first preset temperature T1, a second preset temperature T2, a first adjustment coefficient α1, a second adjustment coefficient α2, a third adjustment coefficient α3 and a fourth adjustment coefficient α4, wherein 0<T1<T2, α1<1<α2<α 3<α4,

[0092] T≤0, adjust Fi to a first corresponding value Fia=Fi×α1

[0093] 0<T≤T1, adjust Fi to a second corresponding value Fib=Fi×α2

[0094] T1<T≤T2, adjust Fi to a second corresponding value Fic=Fi×α3

[0095] T2<T, adjust Fi to a second corresponding value Fid=Fi×α4. It is ensured that the component installed at each stage meets the construction standard, the construction quality is ensured, and the construction efficiency is improved.

[0096] Please continue to refer to Figures 1 to 4 , the prestressed pipe installation selects a metal corrugated pipe as the prestressed pipe, the cap beam prestress adopts an intelligent tensioning process, the prestressed steel bar is arranged in the transverse bridge direction, the prestressed steel bar adopts a steel strand, the metal corrugated pipe is installed first, the metal corrugated pipe is perpendicular to the anchor pad, after the installation of the metal corrugated pipe is completed, the steel strand is used to pass through the steel bar of the metal corrugated pipe.

[0097] Specifically, the prestressed tensioning adopts a post-tensioning intelligent tensioning construction process, and the tensioning is sequentially performed in left-right symmetry, and the prestressed tensioning steps are:

[0098] 1. Tensioned to 10% of tension control tonnage

[0099] 2. Tensioned to 30% of tension control tonnage

[0100] 3. Tensioned to 100% of tension control tonnage

[0101] 4. Hold for 2 minutes

[0102] 5. Anchoring

[0103] Wherein the tensioning is controlled by tension force and elongation, and the tension force is mainly controlled, and the elongation value of the steel strand is used as a check.

[0104] Specifically, the preloading adopts three-stage loading and one-stage unloading, and is gradually loaded at 60%, 80%, and 105% of the preloading load, and then the load is completely unloaded, and the unloading is symmetrical, balanced, and synchronous.

[0105] Specifically, the concrete pouring is performed by an arm pump, and the concrete is poured and vibrated in layers in the full cross section.

[0106] Specifically, the formwork removal needs to remove the end formwork first, and the side formwork is removed from both ends to the middle in pieces, and the bottom formwork needs to be removed after the prestressed beam tensioning, grouting, and unloading are completed. After the end and side formworks are removed and the formwork and the concrete surface are completely separated, the formwork is lifted to the designated position. After the formwork is removed, the formwork should be cleaned, repaired, and painted with a maintenance agent in a timely manner to strengthen the maintenance and maintenance of the formwork. Then, the bottom formwork and the support are removed, and the support is removed after all the prestressed beams are tensioned and grouted. The overall unloading is performed first, and then the principle of first assembling and then disassembling is followed.

[0107] Thus, the technical solutions of the present application have been described in connection with the preferred embodiments shown in the drawings, but those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical solutions after the changes or replacements will fall within the protection scope of the present application.

[0108] The above only describes the preferred embodiments of the present application and is not used to limit the present application; for those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A construction method for prefabricated large cantilever cap beams, characterized in that, include: Step S1, Construction Preparation: Based on the land area required for the construction of the prefabricated large cantilever cap beam and the requirements for ground road traffic, reserve the required area of ​​the construction site and determine the specific location of the concrete supports. Step S2, measurement and layout: A pressure detection device, a temperature monitoring device and a central control unit are set in the concrete support. After the concrete support is poured, before the cap beam is constructed, the construction personnel use a total station to lay out the edge line of the cap beam. Before the formwork is installed, the construction personnel lay out to determine the safe position of the formwork and the concrete pouring height. Before the concrete is poured, the construction personnel re-measure the axis of the top of the cap beam. Step S3: Installation of the load-bearing bracket. Construction personnel use a control network to locate and level the base points of the load-bearing bracket. In the first stage of installation, the unloading blocks and columns are installed. On the ground, the diagonal bracing channel steel and diagonal bracing steel pipe are connected. The connected channel steel and diagonal bracing steel pipe are hoisted to the corresponding position by a crane. Then, the diagonal bracing is connected to the steel column with pins and installed symmetrically. Finally, the diagonal bracing steel pipe is installed horizontally. In the second stage of installation, the main crossbeam consists of three sections. After being assembled on the ground, it is hoisted as a whole by a crane. The crossbeam is connected to the steel column first, and then the top pins of the diagonal bracing are installed. The third stage of installation involves first installing the horizontal bracing between the main crossbeams, followed by installing the distribution beams, bottom formwork, templates, and work platform. During the installation of the load-bearing bracket, the central control unit compares the pressure F0 borne by the support detected by the pressure detection device with the preset pressure to check whether the installation meets the construction standards. The central control unit is equipped with a preset pressure Fi for the i-th stage, a first preset pressure difference ΔF1, and a second preset pressure difference ΔF2, where ΔF1 < ΔF2, and i = 1, 2, 3. If Fi = FO, then the installation meets the construction standards; If Fi≠F0, it is initially determined that the installation does not meet the construction standards. The difference between Fi and F0, ΔF, is calculated and compared with ΔF1 and ΔF2 respectively to determine whether the installation of the load-bearing bracket meets the construction standards. ΔF = 1F0 - Fi1 is set. If △F≤△F1, then the pressure error is within the allowable range and the installation meets the construction standards; If △F1<△F≤△F2, the central control unit determines that the pressure deviation is caused by improper connection and installation of the components, and the on-site construction personnel check and adjust the connection status of the components. If △F2 < △F, the central control unit determines that the installation does not meet the construction standards and checks whether the qualification rate of the components installed in this stage meets the standards. When the pressure detection device measures ΔF2 < ΔF, the central control unit checks whether the pass rate of the components installed in this stage meets the standard. It also checks whether the components installed in this stage are qualified by comparing the difference between ΔF and ΔF2, ΔF0, with a preset pass difference. Let ΔF0 = ΔF - ΔF2. The central control unit has a preset pass difference ΔF', a first preset pass quantity N1, and a second preset pass quantity N2, where N1 < N2. If ΔF0 < ΔF', the central control unit determines that the components installed at this stage are qualified, and considers whether external pressure was applied due to special weather conditions. If △F0≥△F', the central control unit determines that the components installed in this stage are unqualified. It checks and counts the number of qualified components in this stage to determine whether the pass rate of this batch of components meets the standard. The central control unit records the number of qualified components in this stage as N. If N < N1, then the pass rate of this batch of parts is not up to standard; If N1≤N<N2, then most parts are usable, and qualified parts with △F0<△F' are selected. If N≥N2, then the pass rate of this batch of parts meets the standard; Step S4: Roughening the top of the pier. Construction workers use a combination of pneumatic picks and manual labor to roughen the top of the pier. Before roughening, the construction workers lay out and mark the position where the cap beam will be embedded in the top of the pier. After roughening, the concrete residue is removed. Step S5: Installation of cap beam reinforcement and prestressed ducts. Construction workers assemble the reinforcement cage, install the pre-embedded reinforcement of the support pad stone, and install concrete pads at the bottom of the reinforcement cage. After the concrete pads are installed, construction workers use a crane to lift the reinforcement cage. Step S6: Install the template, pour concrete into the cap beam and cure the poured cap beam, apply preload and tension the cap beam, and finally remove the support template.

2. The construction method for prefabricated large cantilever cap beams according to claim 1, characterized in that, When △F1 < △F ≤ △F2, the central control unit compares the first acceptable difference △Fa with the second acceptable difference △Fb to determine how the construction personnel should adjust the connection and installation of the components, where △Fa = 1△F - F1, △Fb = 1△F - F2. If 0 < △Fa < △Fb, then the construction personnel should check and adjust the connection and installation angle of the components; If △Fa≥△Fb, then the construction personnel need to dismantle the components and reconnect and install them.

3. The construction method for prefabricated large cantilever cap beams according to claim 2, characterized in that, The central control unit controls the external temperature T of the temperature monitoring device during the installation of the load-bearing bracket and adjusts Fi to the corresponding value according to the fluctuation value of T. The central control unit has a first preset temperature T1, a second preset temperature T2, a first adjustment coefficient α1, a second adjustment coefficient α2, a third adjustment coefficient α3, and a fourth adjustment coefficient α4, where 0 < T1 < T2, α1 < 1 < α2 < α3 < α4. If T≤0, the central control unit adjusts Fi to the first corresponding value Fia, and sets Fia=Fi×α1; If 0 < T ≤ T1, the central control unit adjusts Fi to the second corresponding value Fib, and sets Fib = Fi × α2; If T1 < T ≤ T2, the central control unit adjusts Fi to the second corresponding value Fic, and sets Fic = Fi × α3; If T2 < T, the central control unit adjusts Fi to the second corresponding value Fid, and sets Fid = Fi × α4.

4. The construction method for prefabricated large cantilever cap beams according to claim 3, characterized in that, When detecting whether a single component is qualified, the central control unit makes a comprehensive judgment based on the comparison results of the radius R of the steel bar in the component with the preset radius and the comparison results of the mass M of the steel bar with the preset mass. The central control unit has a first preset radius Ra, a second preset radius Rb, a first preset mass Ma and a second preset mass Mb, where Ra < Rb, Ma < Mb. If Ra≤R≤Rb and Ma≤M≤Mb, then the central control unit determines that the component is qualified; If R < Ra, Rb < R, M < Ma, or Mb < M, the central control unit determines that the component is unqualified.

5. The construction method for prefabricated large cantilever cap beams according to claim 1, characterized in that, In step S6, a corrugated metal pipe is used as the prestressed duct and steel strands are used as the prestressed steel strands. When installing the prestressed duct, the corrugated metal pipe is installed first. The corrugated metal pipe is perpendicular to the anchor plate. After the corrugated metal pipe is installed, the steel strands are arranged in a transverse direction to thread the steel strands through the corrugated metal pipe.

6. The construction method for prefabricated large cantilever cap beams according to claim 1, characterized in that, In step S6, the prestressing tensioning adopts a post-tensioning intelligent tensioning construction process, and the tensioning is performed in a left-right symmetrical sequence. The specific steps of prestressing tensioning include: Step S61. Tension to A% of the tension control tonnage. Step S62. Tension to B% of the tension control tonnage. Step S63. Tension to C% of the tension control tonnage. Step S64. Hold load for D minutes. Step S65. Anchoring Among them, tensioning adopts dual control of tension force and elongation, with tension force control as the main control and the elongation value of steel strand as the verification standard.

7. The construction method for prefabricated large cantilever cap beams according to claim 1, characterized in that, The preloading process employs a three-stage loading and a single-stage unloading method. First, the preload is loaded gradually according to E%, F%, and G% of the preload, and then the entire load is unloaded. During unloading, symmetrical, balanced, and synchronous unloading is maintained.

8. The construction method for prefabricated large cantilever cap beams according to claim 1, characterized in that, The concrete was poured using a boom pump, with the concrete being poured and vibrated in layers across the entire cross section.

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