A construction method and control system for the protective demolition of a factory building

Abstract

The present invention discloses a construction method and a control system for the protective demolition of a factory building, comprising the following steps: S1. Demolish the roof and walls; S2. For the reinforced concrete columns that do not need to retain the column structure, destructive demolition is adopted. For the destructive demolition of the reinforced concrete columns, mechanical destructive demolition is carried out one by one by an excavator; S3. For the reinforced concrete columns that need to retain the intact structure of the column body, protective demolition is adopted. Before the protective demolition of the reinforced concrete columns, the root of the I-shaped column corbel is bound with a steel wire rope and tied firmly, and then slowly lifted by a hoisting device; then, slope excavation is carried out at a ratio of 1:0.5 within a certain range of the column foot of the concrete column to expose part of the column foot, and the floating soil is manually cleaned. After that, a wire saw cutting machine is used to carry out static cutting on the concrete column. The present invention solves the problem of the overall safety and stability of the original building during the demolition operation or during the new construction process after demolition, and eliminates the risk of overturning while protecting the original structure from being damaged.

Description

Technical Field

[0001] The present invention relates to the field of building construction. More specifically, the present invention relates to a construction method and a control system for the protective demolition of a factory building. Background Art

[0002] With the acceleration of the urban renewal process, the protective renovation projects of industrial heritage buildings are increasing day by day. The renovation of industrial factory buildings with historical value faces special challenges: it is necessary to completely retain specific structural components for the decorative reconstruction of new buildings, and at the same time, it is necessary to efficiently demolish the non-retained parts. The traditional demolition methods for reinforced concrete structures have significant limitations, especially in the field of protective demolition, and the following problems are exposed: 1) In the mechanical crushing method, a hydraulic breaker is directly used to impact the structure. Although the efficiency is relatively high, it will generate strong vibrations (the measured vibration speed can reach 30 mm / s), which is extremely likely to cause hidden damage to the double-column and adjacent structures in the retention area. In this project, the connection accuracy requirements of the 18 decorative columns to be retained in situ and the new structure are ±5 mm, and the traditional method is difficult to meet. 2) Although the blasting demolition can quickly disassemble the structure, the air shock wave (peak overpressure > 0.1 MPa) and flying debris generated by it pose a safety threat to the existing buildings within 50 m. The project site is adjacent to the main road (the closest distance is 9.6 m), and it is completely not suitable for implementation. 3) Due to the defects of the existing static cutting technology, such as open-loop control of the cutting depth, empirical lifting intervention, insufficient monitoring accuracy, and discrete equipment coordination, there are uncontrollable instability risks and efficiency losses during the demolition process. Summary of the Invention

[0003] The purpose of the present invention is to provide a construction method and a control system for the protective demolition of a factory building, to solve the problem of the overall safety and stability of the original building during the demolition operation or the new construction process after demolition, and to eliminate the overturning risk while protecting the original structure from being damaged.

[0004] The technical solution adopted by the present invention to solve this technical problem is: a construction method for the protective demolition of a factory building, including the following steps:

[0005] S1. Demolish the roof and walls;

[0006] S2. For the reinforced concrete columns that do not need to retain the column structure, destructive demolition is adopted, and the destructive demolition of the reinforced concrete columns is carried out by a excavator one by one for mechanical destructive demolition;

[0007] S3. For the reinforced concrete columns that need to retain the intact structure of the column body, protective demolition is adopted. Before the protective demolition of the reinforced concrete column, the root of the bracket of the I-shaped column is bound with a steel wire rope and firmly tied. Then, it is slowly lifted by a hoisting device. After that, a slope of 1:0.5 is excavated within a certain range of the column foot of the concrete column to expose part of the column foot, and the floating soil is manually cleaned. Then, a wire saw cutting machine is used to perform static cutting on the concrete column.

[0008] As a further solution of the present invention: specifically included in S1 is:

[0009] S11. Protective reinforcement construction. Steel pipe scaffolds are erected for protection, and the structural columns to be retained are first reinforced. Specifically: column bracings are added between the first-span structural column and the last-span structural column, and all the original column bracings are retained. Horizontal connecting tie rods are provided between each span of structural columns. Then, the upper part of the column foot and the lower part of the bracket of the column bracing are fixed to the structural column in the form of a hoop.

[0010] S12. Demolition operation:

[0011] S12a. Roof demolition: The precast slabs and ring beams are separated one by one, and the slabs are lifted by a crane and lowered to the ground for recycling or crushing.

[0012] S12b. Wall demolition: The wall is demolished from top to bottom, and the height of each demolition does not exceed 1000 mm. The brick slag after demolition is transported by an excavator to a designated place on the site for storage and used for laying the temporary access road on the site.

[0013] S12c. Steel roof truss demolition: According to the principle of from top to bottom, first non-load-bearing and then load-bearing, the steel truss is first pre-tensioned upward by a crane, and the connection points of the steel truss are released one by one, and then it is gently lowered to the ground.

[0014] As a further solution of the present invention: the specific implementation of the column bracing and column tie rod connection in the first span and the last span in S11 includes: vertical poles, longitudinal horizontal bars, transverse horizontal bars, column clamps, and inverted V-shaped diagonal tie rods; the vertical poles, longitudinal horizontal bars, and transverse horizontal bars are combined to form the scaffold body. The scaffold body is connected to the original concrete structural column through the column clamp, and the inverted V-shaped diagonal tie rod is tied and fixed to the original concrete structural columns on both sides corresponding to it.

[0015] As a further solution of the present invention: the specific steps of using a wire saw to perform static cutting on the concrete column in S3 are as follows:

[0016] S31. Install pressure sensors and displacement sensors in the predetermined cutting area of the reinforced concrete column to collect the axial pressure value F and the column body offset ΔL during the cutting process in real time.

[0017] S32. Obtain the cutting wire speed v in real time through the wire speed sensor of the wire saw cutting machine, and record the effective cutting time t by the timer;

[0018] S33. Input the wire speed v, cutting time t, and axial pressure value F into the central control unit. According to the pre-stored material strength coefficient k and cutting efficiency coefficient η, calculate the real-time cutting depth h according to the formula h = η·v·t·(F / k) 0.5 ;

[0019] S34. When the calculated cutting depth h reaches 80 - 90% of the critical cutting depth H g , control the lifting sling of the lifting equipment to apply prestress to 0.2 - 0.3 times the self-weight of the column, and synchronously adjust the feed rate of the wire saw cutting machine to 50 - 60% of the initial rate;

[0020] S35. Continuously monitor the column offset ΔL. When ΔL ≥ 0.15H g , immediately stop cutting and start the synchronous lifting program of the lifting equipment until the cutting section is completely separated and then implement directional transfer.

[0021] As a further solution of the present invention: The pressure sensors are symmetrically arranged on both side surfaces of the reinforced concrete column along the axial direction of the reinforced concrete column, 20 - 30 cm above the predetermined cutting line.

[0022] As a further solution of the present invention: The displacement sensor includes a horizontal displacement sensor and a vertical displacement sensor; the horizontal displacement sensor is installed on the side surface of the reinforced concrete column 10 - 15 cm above the cutting line to monitor the lateral offset; the vertical displacement sensor is installed at the center point of the column top to monitor the vertical settlement.

[0023] As a further solution of the present invention: The vertical displacement sensor is a laser emitter and a reflection target. Among them, the laser emitter is installed adjacent to the stable structure, with a horizontal distance of 5 - 10 m from the column to be cut, and the reflection target is installed on the column top of the column to be cut.

[0024] As a further solution of the present invention: The calculation method of the column offset ΔL in S35 includes:

[0025] The horizontal displacement sensor collects the lateral offset ΔL at 10 - 15 cm above the cutting line in real time h , and the vertical displacement sensor collects the vertical settlement amount ΔL at the center point of the column top in real time v ;

[0026] Calculate the total offset effect during the column tipping process: , where H is the total height of the reinforced concrete column, and H' is the height difference between the vertical displacement sensor and the cutting line.

[0027] The present invention also provides a control system for the construction method of the protective demolition of the plant building, including:

[0028] A sensor module, which is composed of at least two groups of axial pressure sensors and displacement sensors installed on both sides of the predetermined cutting area of the reinforced concrete column;

[0029] A wire saw parameter acquisition module, including a linear velocity sensor and a timer integrated on the drive motor of the wire saw cutting machine, for real-time acquisition of the cutting line speed v and the effective cutting time t;

[0030] A data communication module, which sends the data of the sensor module and the wire saw parameter acquisition module to the central control unit through wired / wireless transmission;

[0031] A central control unit, in which a calculation module is set. The calculation module prestores the material strength coefficient k and the cutting efficiency coefficient η, and executes the real-time operation of the formula h = η·v·t·(F / k) 0.5 and outputs the cutting depth h and the critical state determination signal;

[0032] An execution module, including a lifting equipment controller and a wire saw feed rate regulator. After receiving the critical state determination signal, the lifting equipment controller controls the lifting tackle to apply a prestress of 0.2 - 0.3 times the self-weight of the column, and at the same time, the wire saw feed rate regulator reduces the cutting rate to 50 - 60% of the initial value;

[0033] A safety redundancy module. When the displacement sensor detects that ΔL≥0.15H g it triggers an emergency stop instruction to cut off the power supply of the wire saw and activate the synchronous lifting program of the lifting.

[0034] The present invention has at least the following beneficial effects:

[0035] 1. By using scaffolding and structural reinforcement to improve the safety of demolition, eight-shaped diagonal tie rods and horizontal tie rods are added to the first and last spans, the lateral stiffness of the cantilever column is improved, and the displacement during the demolition process is ≤2 mm.

[0036] 2. After the protective demolition, high reuse rate of components is achieved. Through the coordinated control of wire saw static cutting and lifting, the reinforced concrete column is completely retained and used for the decorative components of the new building. The flatness error of the cutting surface is ≤3 mm (the traditional method > 10 mm), meeting the precision requirements of decorative installation. The reuse of components reduces construction waste and carbon emissions.

[0037] 3. Based on the formula designed in this application, the dynamic cutting depth is combined with the suppression of instability risk, and the error is compressed from ±15% of the traditional empirical method to ±5%. The critical depth threshold triggers the lifting prestress (0.2 - 0.3 times the self-weight) and the wire saw speed reduction (50 - 60%), forming a double redundancy protection mechanism.

[0038] Other advantages, objectives and features of the present invention will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the present invention. Brief Description of the Drawings

[0039] Figure 1 is the crane stationing schematic diagram for demolishing reinforced concrete columns of the present invention;

[0040] Figure 2 is the elevation schematic diagram for strengthening the structural columns of the present invention;

[0041] Figure 3 is the connection schematic diagram of the first and last bay column bracings and the column bracings between columns of the present invention;

[0042] Figure 4 is the schematic diagram of the control system of the present invention.

[0043] Wherein, 1 - crane, 2 - I-shaped column, 3 - additional column bracing, 4 - original column bracing, 5 - horizontal connecting tie rod, 6 - vertical pole, 7 - longitudinal horizontal bar, 8 - transverse horizontal bar, 9 - column embracing member, 10 - inverted V-shaped diagonal tie rod. Detailed Description of the Preferred Embodiments

[0044] The present invention will be described in detail and completely below in conjunction with the drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the drawings, it should be particularly noted that: the technical solutions and technical features provided in each part including the following description of the present invention can be combined with each other without conflict.

[0045] In addition, the embodiments of the present invention involved in the following description are usually only a part of the embodiments of the present invention, rather than all the embodiments. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0046] The following further describes the present invention in detail in conjunction with the drawings and embodiments, and the specific implementation process is as follows:

[0047] The core purpose of the protective demolition of reinforced concrete columns is to preserve the unique style of historical buildings. Historical buildings in different regions often have their own characteristics, and their concrete columns carry the local regional cultural imprints. When these concrete columns are subjected to protective demolition and the corresponding buildings are renovated, the concrete columns that are completely preserved will become decorative columns (without the function of load-bearing structures) and will be installed in the renovated factory buildings. In this way, the new factory buildings can still retain the extremely historical and unique style contained in the local buildings.

[0048] When carrying out the protective demolition work on reinforced concrete columns, there is no established and clear demolition quantity standard. Exactly how many to demolish often needs to be comprehensively determined based on the design plan and actual needs of each building. After determining the quantity of the protective demolition of reinforced concrete columns for each project (this quantity should be slightly more than the quantity of the actually designed decorative columns as an alternative), the remaining reinforced concrete columns can be demolished destructively.

[0049] This demolition project includes three factory buildings: Workshop 1, Workshop 2, and Steel Plate Warehouse. The main structure of the factory buildings to be demolished is a reinforced concrete double-column + steel roof truss structure, with a designed service life of 50 years, a seismic fortification category of Class B, a building structure safety grade of Grade II (including the foundation), a seismic intensity of 6 degrees, and a frame seismic grade of Grade IV.

[0050] The present invention provides a construction method for the protective demolition of a factory building, including the following steps:

[0051] S1. Demolish the roof and walls;

[0052] S2. Demolish destructively the reinforced concrete columns that do not need to retain the column structure. The destructive demolition of the reinforced concrete columns is carried out by using an excavator one by one for mechanical destructive demolition;

[0053] S3. Demolish protectively the reinforced concrete columns that need to retain the complete structure of the column body. Before the protective demolition of the reinforced concrete columns, bind the root of the I-shaped column corbel with a steel wire rope and tie it firmly. As Figure 1 shown, then slowly lift it with a hoisting device; then carry out a 1:0.5 slope excavation within a certain range (3.3 m in this embodiment) at the column foot of the concrete column to expose part of the column foot, and use manual labor to clean the floating soil. After that, use a rope saw cutting machine to carry out static cutting on the concrete column to ensure the integrity of the component.

[0054] Specifically, as Figure 2 shown, the specific content in S1 includes:

[0055] S11. Carry out protection and reinforcement construction, and adopt the method of erecting a steel pipe scaffold for protection. Specifically:

[0056] Level the site and clean the ground debris around the buildings to be demolished. The ground of the scaffolding foundation is the original cement-hardened ground with a concrete thickness of about 200 mm. The damaged parts of the original concrete ground are repaired by hardening with C20 concrete to meet the requirements for scaffolding erection.

[0057] According to the requirements of the frame design dimensions, determine the positions of the inner and outer rows of vertical poles. The distance between the inner vertical pole of the frame and the exterior wall is 300 mm, and the distance between the inner and outer rows of vertical poles of the scaffolding is 900 mm. A continuous base plate should be set at the bottom of each vertical pole, and longitudinal and transverse ground-sweeping bars must be set. The longitudinal ground-sweeping bar should be fixed to the vertical pole not more than 200 mm above the upper surface of the base with right-angle fasteners. The transverse ground-sweeping bar should also be fixed to the vertical pole immediately below the longitudinal ground-sweeping bar with right-angle fasteners. The longitudinal horizontal bar should be preferably set inside the vertical pole, and its length should not be less than three spans. The step distance of the longitudinal horizontal bar is 1800 mm; an additional handrail horizontal bar is erected between the two outer horizontal bars, and the distance between the longitudinal horizontal bars is 900 mm; two additional longitudinal horizontal bars are added between the longitudinal horizontal bars for erecting the hard protection layer and are evenly arranged. The transverse horizontal bar (small cross bar) is installed above the longitudinal horizontal bar, and the distance between the transverse horizontal bars at the operation layer is 750 mm, and the distance between the transverse horizontal bars at the non-operation layer is 1500 mm. The scaffolding and the building are rigidly connected by steel pipe tie-in members, that is, the scaffolding and the structural columns in the original building are reliably connected together by using steel pipes, fasteners, etc. The setting spacing of the tie-in members: the horizontal spacing is 6000 mm; the vertical spacing is 5400 mm. The tie-in members are all connected to the load-bearing columns by the method of hugging the columns. According to the height of the scaffolding, the scaffold boards are fully laid on the first layer, every 5 steps and the operation layer; the scaffold boards should be laid stably, leaving 120 - 150 mm from the wall surface, and toe boards are set at the operation layer and the periphery of the platform. The height of the scaffolding in this project is basically below 24 m, and on the outer side ends, corners and the elevations with an interval not exceeding 15 m in the middle, a diagonal brace is set for each, and it is continuously set from the bottom to the top and painted with red and white paint. The outer side elevation of the scaffolding is fully enclosed with close-mesh safety nets, and the close-mesh safety nets should be set inside the outer row of vertical poles.

[0058] Considering that after the removal of the workshop roof truss structure, the structural columns are in an independent cantilever state, to ensure the safety and stability during the removal process and when retained in situ after removal, the structural columns to be retained are first strengthened to prevent the structural columns from losing stability and collapsing during the removal of the roof and walls. Specifically: Add column bracing 3 between the first-span structural column and the last-span structural column, and all the original column bracings 4 are retained. Horizontal connecting tie rods 5 are provided between each span of structural columns, and then the upper part of the column feet and the lower part of the brackets of the column bracings are fixed to the structural columns in the form of hoop clamps;

[0059] S12. Demolition operation:

[0060] S12a. Roof removal: Separate the precast slabs, ring beams, etc. one by one, lift the slabs with a 100T crane 1, and lower them to the ground for recycling or crushing;

[0061] S12b. Wall demolition: The wall is demolished from top to bottom, with the height of each demolition not exceeding 1000 mm. The brick debris after demolition is transported by an excavator to a designated place on site for storage and used for laying the temporary access road on site.

[0062] S12c. Steel roof truss demolition: In accordance with the principle of from top to bottom, first non - load - bearing and then load - bearing, first use a 100T crane to pre - tension the steel frame upward, release the connection points of the steel frame one by one, and then gently lower it to the ground.

[0063] Specifically, as Figure 3 shown, the specific implementation of the column - to - column bracing and the connection of the column - to - column tie rods in the first and last spans in S11 includes: vertical poles 6, longitudinal horizontal bars 7, transverse horizontal bars 8, column - holding members 9, and inverted - V - shaped diagonal braces 10; the vertical poles, longitudinal horizontal bars, and transverse horizontal bars are combined to form the scaffold body. The scaffold body is connected to the original concrete structure column through the column - holding members, and the inverted - V - shaped diagonal braces are tied and fixed to the original concrete structure columns on both sides corresponding to them to ensure the overall stability of the scaffold.

[0064] Specifically, the static cutting of the concrete column using a wire saw in S3 specifically includes the following steps:

[0065] S31. Install pressure sensors and displacement sensors in the predetermined cutting area of the reinforced concrete column to collect the axial pressure value F and the column body offset ΔL during the cutting process in real - time.

[0066] S32. Obtain the cutting wire speed v in real - time through the wire speed sensor of the wire saw cutting machine, and record the effective cutting time t by a timer.

[0067] S33. Input the wire speed v, cutting time t, and axial pressure value F into the central control unit. According to the pre - stored material strength coefficient k and cutting efficiency coefficient η, calculate the real - time cutting depth h according to the formula h = η·v·t·(F / k) 0.5 Calculate the real - time cutting depth h.

[0068] The material strength coefficient k is the comprehensive strength coefficient of the reinforced concrete column to resist damage during cutting: k = 0.85f c +0.15·p·f y , where f c is the axial compressive strength of the concrete, f y is the yield strength of the steel bar, and p is the reinforcement ratio.

[0069] The cutting efficiency coefficient η is the effective cutting efficiency of the wire saw cutting machine for the reinforced concrete column per unit time, η = actual cutting capacity / theoretical cutting capacity, and the actual cutting capacity can be obtained through cutting tests on the reinforced concrete columns demolished destructively on site.

[0070] S34. When the cutting depth h < 0.8 - 0.9H g and ΔL < 0.15H g , the column may have a millimeter - level offset due to the redistribution of the load (such as ΔL≈0.05H), but dynamic stability can be maintained through prestress and rate adjustment. When the calculated cutting depth h reaches 80 - 90% of the critical cutting depth H g , apply prestress to 0.2 - 0.3 times the self - weight of the column by controlling the lifting tackle of the lifting equipment, and synchronously adjust the feed rate of the wire saw cutting machine to 50 - 60% of the initial rate; where the critical cutting depth H g refers to the cutting depth threshold when the flexural bearing capacity of the remaining cross - section of the reinforced concrete column is insufficient to balance the external loads (self - weight, wind load) during the cutting process. During the construction of this project, the critical cutting depth H g of the reinforced concrete column is uniformly defined as 0.8m through calculation.

[0071] S35. Continuously monitor the column offset ΔL. When ΔL≥0.15H g , immediately stop cutting and start the synchronous lifting program of the lifting equipment to avoid accelerating tipping until the cutting section is completely separated and then implement directional transfer.

[0072] Taking the I - shaped concrete column to be demolished in this embodiment as an example, the column length is 16.55m. After preliminary estimation, the weight of a single I - shaped column 2 is about 27t. Using a Zoomlion ZTC100T truck crane and equipped with a 6·37 - φ32.5mm steel wire rope (indicating that the steel wire rope is made up of 6 strands; there is a fiber rope core in the middle of each strand and 37 steel wires on the periphery; the diameter of the steel wire rope is 32.5mm), the maximum measured offset is 3.4mm under the above - mentioned same control strategy (H g = 800mm, ΔL = 0.15H g ), which is far lower than the critical threshold.

[0073] In the above - mentioned technical solution, as the cutting depth increases, the bearing capacity of the remaining cross - section of the column gradually decreases. If the matching of the cutting rate and the lifting prestress is insufficient, it may cause the column to have a progressive tilt under the action of gravity or external loads (such as wind load). Therefore, innovative improvements have been made during the static cutting process. The critical value of the offset ΔL is set to 0.15H g , indicating that a limited and controllable small tilt of the column during cutting is allowed. In addition, the timing of applying prestress has also been improved. After h reaches the critical threshold, the wire saw feed rate is reduced to 50 - 60% of the initial value, slowing down the weakening speed of the remaining cross - section, providing time for stress redistribution for the lifting system, being able to accurately offset the overturning moment caused by cutting, and reducing the risk of sudden tilt.

[0074] Specifically, the pressure sensors are symmetrically arranged on the surfaces of both sides of the reinforced concrete column along the axial direction of the reinforced concrete column, 20-30 cm above the predetermined cutting line (avoiding the cutting heat affected zone). The pressure sensors are used to monitor the changes in the axial pressure distribution of the remaining cross-section of the column during the cutting process, reflecting the load transfer status.

[0075] Specifically, the displacement sensor includes a horizontal displacement sensor and a vertical displacement sensor; the horizontal displacement sensor is installed on the side of the reinforced concrete column 10-15cm above the cutting line to monitor the lateral offset; the vertical displacement sensor is installed at the center point of the top of the column to monitor the vertical settlement, capture the deformation caused by cutting in real time, and prevent sudden tilt. Among them, the axis of the horizontal displacement sensor is parallel to the predetermined cutting surface, and the axis of the vertical displacement sensor is orthogonal to the axis of the horizontal displacement sensor.

[0076] Specifically, in order to avoid direct impact of cutting vibration on the vertical displacement sensor and affect the detection accuracy, the vertical displacement sensor is a laser emitter and a reflective target, wherein the laser emitter is installed in an adjacent stable structure (such as an undemolished floor slab, an independent pile foundation), with a horizontal distance of 5-10m from the column to be cut, and a reflective target is installed on the top of the column to be cut to form a non-contact measurement to avoid interference with the cutting operation.

[0077] Specifically, the calculation method of the column offset ΔL in S35 includes:

[0078] The horizontal displacement sensor collects the lateral offset ΔL at 10-15cm above the cutting line in real time h , the vertical displacement sensor collects the vertical settlement ΔL of the center point of the column top in real time v ;

[0079] Calculate the total deflection effect during column tipping: , where H is the total height of the reinforced concrete column, and H' is the height difference from the vertical displacement sensor to the cutting line (i.e. H' = H - cutting line height). In this technical solution, the dual sensors work together to achieve accurate quantification of the tilt state. ΔL is calculated by height ratio conversion v , avoid ignoring the amplification effect of column top settlement on the tipping moment. Specific implementation requirements: The sensor needs to be zero-calibrated before cutting (collect 10 sets of data in a static environment and take the average value); when installing the vertical displacement sensor, the laser transmitter should be fixed on an independent reference pile to avoid interference from surrounding vibrations.

[0080] The present invention also provides a control system for the protective demolition construction method of the factory building, such as Figure 4 As shown, including:

[0081] The sensor module consists of at least two groups of axial pressure sensors and displacement sensors installed on both sides of the predetermined cutting area of the reinforced concrete column;

[0082] The wire saw parameter acquisition module includes a linear velocity sensor and a timer integrated on the drive motor of the wire saw cutting machine, which are used to obtain the cutting wire speed v and the effective cutting time t in real time;

[0083] The data communication module sends the data of the sensor module and the wire saw parameter acquisition module to the central control unit through wired / wireless transmission;

[0084] The central control unit is provided with a calculation module. The calculation module prestores the material strength coefficient k and the cutting efficiency coefficient η, and executes the real-time operation of the formula h = η·v·t·(F / k) 0.5 and outputs the cutting depth h and the critical state determination signal; the central control unit synchronously coordinates the wire saw and the hoisting equipment, can respond quickly, and the cutting efficiency is increased by 2.5 times (the time taken to demolish a single column using this solution is 1.8 h, and the time taken to cut a single column using the traditional wire saw is 4.5 h).

[0085] The execution module includes a hoisting equipment controller and a wire saw feed rate regulator. After receiving the critical state determination signal, the hoisting equipment controller controls the lifting rigging to apply a prestress of 0.2 - 0.3 times the self-weight of the column, and at the same time the wire saw feed rate regulator reduces the cutting rate to 50 - 60% of the initial value;

[0086] The safety redundancy module, when the displacement sensor detects that ΔL≥0.15H g triggers an emergency stop command to cut off the power supply of the wire saw and activate the synchronous lifting program of the hoisting.

[0087] Taking a workshop as an example: 30 I-shaped reinforced concrete columns were demolished protectively. After the completion of the main structure of the new building, 20 I-shaped columns were selected and moved to the main venue of the new forum as decorative components without bearing structural loads. During the demolition of 30 I-shaped reinforced concrete columns in the workshop project, there were no tipping accidents throughout the process, the structural displacement was <5 mm, the total construction period was shortened by 45%, the cost was saved by 1.2 million yuan, about 180 tons of construction waste was reduced, and the carbon emissions were reduced by 30%.

[0088] Although the embodiments of the present invention have been disclosed as above, it is not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the embodiments shown and described here.

Claims

1. A construction method for the protective demolition of a factory building, characterized in that, The following steps are involved: S1. Demolition of roof and walls; S2. Destructive demolition is used for reinforced concrete columns that do not need to retain the column structure. Destructive demolition of reinforced concrete columns is carried out mechanically one by one using an excavator; S3. Protective demolition is adopted for reinforced concrete columns that need to retain the complete structure of the reinforced concrete column. Before protective demolition of reinforced concrete columns, the roots of the I-shaped column corbels are tied with steel wire ropes and tied firmly, and then slowly lifted with lifting equipment; then, a 1:0.5 slope excavation is carried out within a certain range of the column foot of the concrete column to expose part of the column foot, and the loose soil is cleaned manually, and then the concrete column is statically cut with a rope saw cutter; The static cutting of the concrete column by using a rope saw in S3 specifically comprises the following steps: S31, installing a pressure sensor and a displacement sensor in a predetermined cutting area of ​​a reinforced concrete column, and collecting the axial pressure value F and the column offset ΔL in real time during the cutting process; S32, obtaining the cutting line speed v in real time through the line speed sensor of the wire saw cutting machine, and recording the effective cutting time t by a timer; S33. Input the linear velocity v, cutting time t, and axial pressure value F into the central control unit, and calculate the real-time cutting depth h according to the formula h = η·v·t·(F / k) through the pre-stored material strength coefficient k and cutting efficiency coefficient η 0.5 Calculate the real-time cutting depth h; S34. When the calculated cutting depth h reaches 80 - 90% of the critical cutting depth H g apply prestress to the lifting tackle of the lifting equipment to 0.2 - 0.3 times the self-weight of the column, and synchronously adjust the feed rate of the wire saw cutting machine to 50 - 60% of the initial rate; S35. Continuously monitor the offset ΔL of the column. When ΔL≥0.15H g immediately stop cutting and start the synchronous lifting procedure of the hoisting equipment until the cutting section is completely separated and then implement directional transfer.

2. The construction method for the protective demolition of the factory building according to claim 1, characterized in that, The S1 specifically includes: S11. Protection and reinforcement construction, adopt the steel pipe scaffolding protection, and the structural columns that need to be retained shall be reinforced first, specifically: add column supports to the first span structural columns and the last span structural columns, retain all the original column supports, connect tie rods horizontally between the structural columns of each span, and then fix the upper part of the column foot and the lower part of the corbel of the column support to the structural column in the form of a hoop; S12. Demolition work: S12a, roof dismantling: separate the prefabricated panels and ring beams piece by piece, lift the panels with a crane, and lower them to the ground for recycling or crushing; S12b, wall demolition: the wall is demolished from top to bottom, and the demolition height each time does not exceed 1000mm. The brick slag after demolition is transported by excavator to the designated place on site for storage and used for paving temporary access roads on site; S12c. Dismantling of steel roof trusses: From top to bottom, first non-load-bearing and then load-bearing, use a crane to pre-tension the steel frame upwards, release the steel frame connection points one by one, and then lower it steadily to the ground.

3. The construction method for the protective demolition of the factory building according to claim 2, characterized in that, The support between the columns of the first span and the last span and the connection of the tie rods between the columns in S11 specifically include: vertical poles, longitudinal horizontal poles, transverse horizontal poles, brackets and figure-eight diagonal rods; the vertical poles, longitudinal horizontal poles and transverse horizontal poles are combined to form a scaffolding body, and the scaffolding body is connected to the original concrete structure columns through the brackets, and the figure-eight diagonal rods are tied and fixed to the original concrete structure columns on both sides thereof.

4. The construction method for the protective demolition of the factory building as described in claim 1, wherein, The pressure sensors are symmetrically arranged on the surfaces of both sides of the reinforced concrete column along the axial direction of the reinforced concrete column and 20-30 cm above the predetermined cutting line.

5. The construction method of the protective demolition of the factory building according to claim 4, characterized in that, The displacement sensor includes a horizontal displacement sensor and a vertical displacement sensor; the horizontal displacement sensor is installed on the side of the reinforced concrete column 10-15 cm above the cutting line to monitor the lateral offset; the vertical displacement sensor is installed at the center point of the top of the column to monitor the vertical settlement.

6. The construction method for the protective demolition of the factory building as described in claim 5, characterized in that, The vertical displacement sensor is a laser emitter and a reflective target, wherein the laser emitter is installed near a stable structure, with a horizontal distance of 5-10m from the column to be cut, and a reflective target is installed on the top of the column to be cut.

7. The construction method for the protective demolition of the factory building as described in claim 6, characterized in that, The calculation method of the offset ΔL of the S35 middle column includes: The horizontal displacement sensor collects the lateral offset ΔL at a position 10 - 15 cm above the cutting line in real time h The vertical displacement sensor collects the vertical settlement ΔL of the center point at the top of the column in real time v ; Calculate the total offset effect during the tipping process of the column: , where H is the total height of the reinforced concrete column and H' is the height difference between the vertical displacement sensor and the cutting line.

8. A control system for the construction method of the protective demolition of the factory building according to any one of claims 4 to 7, comprising: A sensor module, which consists of at least two groups of axial pressure sensors and displacement sensors installed on both sides of the predetermined cutting area of the reinforced concrete column; A wire saw parameter acquisition module, which is a linear velocity sensor and a timer integrated on the drive motor of the wire saw cutting machine, and is used to obtain the cutting linear velocity v and the effective cutting time t in real time; A data communication module, which sends the data of the sensor module and the wire saw parameter acquisition module to the central control unit through wired / wireless transmission; A central control unit, which is provided with a calculation module therein. The calculation module prestores a material strength coefficient k and a cutting efficiency coefficient η, and executes real-time calculation of the formula h = η·v·t·(F / k) 0.5 and outputs a cutting depth h and a critical state determination signal; An execution module, which includes a hoisting equipment controller and a wire saw feed rate regulator. After receiving the critical state determination signal, the hoisting equipment controller controls the lifting rigging to apply a prestress of 0.2 - 0.3 times the self-weight of the column, and at the same time the wire saw feed rate regulator reduces the cutting rate to 50 - 60% of the initial value; Safety redundancy module, when the displacement sensor detects that ΔL≥0.15H g it triggers an emergency stop command to cut off the power supply of the wire saw and activate the hoisting synchronous lifting program.

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