A directional blasting demolition method for bridge engineering disease site

Abstract

The application discloses a directional blasting demolition method for bridge engineering disease parts. The application cuts and separates a reserved beam body from an adjacent beam body to be demolished, and cuts and separates beam plates of the beam body to be demolished; water pressure blasting is performed on the beam body to be demolished adjacent to the reserved beam body; a bridge pier and related cross beams between the beam bodies to be demolished are directionally blasted; a dumping direction is controlled; the beam body to be demolished adjacent to the reserved beam body, the bridge pier and the related cross beams between the beam bodies to be demolished are networked and initiated; and steel bars are recycled and the blasting residue is cleaned. The application performs water pressure blasting on the beam body to be demolished adjacent to the reserved beam body, the water pressure blasting generates uniform damage effect in each space of a beam plate box chamber of the beam body to be demolished, and influence of large residual blasting residue on the reserved beam body or other structures is avoided. The application controls the dumping direction, thereby avoiding damage of blasting demolition to living facilities around the bridge or injury of construction personnel, and also makes the later steel bar recycling and blasting residue cleaning far away from a residential area.

Description

Technical Field

[0001] This application relates to the field of blasting engineering technology, specifically a method for directional blasting demolition of damaged parts of bridge engineering. Background Technology

[0002] Bridges are important transportation infrastructures that cross obstacles (such as rivers, canyons, roads, etc.). They not only need to have sufficient strength, rigidity, and stability, but also a certain degree of durability and economy.

[0003] Bridge engineering projects are subject to natural factors, and localized defects may occur during operation, such as pile foundation settlement, pier cracking, and beam separation. In such cases, the defective parts must be removed and replaced with healthy parts to ensure the safe and smooth operation of the bridge project.

[0004] Methods for removing damaged sections of bridges include manual demolition, mechanical demolition, and demolition by blasting. Manual demolition is relatively simple, requires no large equipment, and has lower technical and cost requirements, but it is labor-intensive, slow, and has poor safety. Mechanical demolition is faster than manual demolition and has lower technical requirements, but it requires large equipment and poses certain safety hazards. Demolition by blasting is fast, has low labor intensity, and good safety, but it requires high technical skills and is currently the most commonly chosen method for demolishing similar structures.

[0005] Currently, during demolition by blasting, large chunks of residual debris from the blasting process can damage structures intended to be preserved as they fall. In addition, residential buildings, highways, and other living facilities are usually scattered around bridges, and demolition by blasting may cause damage to them. Summary of the Invention

[0006] This application provides a directional blasting demolition method for damaged parts of bridge engineering, which solves the technical problem that current blasting demolition methods are prone to damaging adjacent structures, causing damage to living facilities around the bridge, or injuring construction workers.

[0007] This application provides a method for directional blasting demolition of bridge engineering defects, including: cutting and separating the beam to be retained from the adjacent beam to be demolished, and cutting and separating the beams and slabs of the beam to be demolished;

[0008] Hydraulic blasting was carried out on the adjacent beams to be demolished;

[0009] Directional blasting is planned to demolish the bridge piers and related transverse beams between the bridge sections.

[0010] Control the tilting direction;

[0011] The plan is to retain the adjacent beams to be demolished, the piers between the beams to be demolished, and the related transverse beams.

[0012] Rebar recycling and slag removal.

[0013] In one possible implementation, the beam to be retained is cut and separated from the adjacent beam to be demolished, and the beams and slabs of the beam to be demolished are cut and separated, including: making a full-section transverse cut of the beam to be retained and the adjacent beam to be demolished, so that it becomes a simply supported beam structure;

[0014] Cut the wet joints between the beams to be demolished longitudinally to prevent the beams and slabs from adhering to each other.

[0015] In one possible implementation, hydraulic blasting is performed on the adjacent beam to be demolished, which includes cutting manholes and charging holes on the top of the adjacent beam to be demolished.

[0016] Enter the beam-slab box chamber of the beam to be demolished adjacent to the beam to be retained, and seal its drainage holes with wooden plugs and waterproof material;

[0017] Water pumps or fire trucks were used to inject water into the beam-slab box chambers of the beams to be demolished adjacent to the beams to be retained;

[0018] Install and secure the medicine pack.

[0019] One possible implementation involves using hydraulic blasting to demolish beams adjacent to the beams to be retained, and also includes: installing PVC pipes on the charging holes; and laying protective netting on the bridge deck.

[0020] In one possible implementation, installing and securing the explosive charges includes: determining the location of the explosive charges, placing them at the geometric center of the beam-slab box chamber of the beam to be demolished adjacent to the beam to be retained, and determining the number of explosive charges and the amount of explosive in each explosive charge;

[0021] The explosive pack and digital electronic detonator were placed in a sealed plastic bag and suspended by ropes in the box chamber of the adjacent beam to be demolished. The end of the rope furthest from the explosive pack was connected to a PVC pipe.

[0022] In one possible implementation, the formula for determining the number of medicine packets is as follows:

[0023] N = (L - 2 × 1.5) ÷ 1.2 (pieces);

[0024] In the formula, N represents the number of medicine packs, L represents the length of the adjacent beam to be dismantled, the distance between the outermost medicine pack hole and the end of the beam to be dismantled is 1.5m, and the distance between adjacent medicine pack holes is 1.2m.

[0025] The formula for determining the amount of medicine in a single medicine packet is as follows:

[0026] The amount of medicine in a single medicine packet = Vq / N;

[0027] In the formula, V represents the masonry volume of the adjacent beam to be demolished, and q represents the explosive consumption per unit volume of reinforced concrete material, with a value of 1.0–2.0 kg / m³. 3 .

[0028] In one possible implementation, directional blasting is used to demolish the piers and related transverse beams between the beams to be dismantled, including:

[0029] Erect scaffolding and construction platforms;

[0030] Determine the locations of blast holes for the bridge piers and related crossbeams;

[0031] Drilling blast holes;

[0032] An explosive charge was installed inside the blast hole and then plugged.

[0033] Cover the blasting area with protective netting;

[0034] Dismantle the scaffolding and evacuate personnel and machinery.

[0035] In one possible implementation, the formula for determining the locations of blast holes for the piers and related transverse beams between the beams to be demolished by directional blasting includes:

[0036] The distance between blast holes, a = (1.2~1.5)W;

[0037] The spacing between blast holes, b = (0.7~0.9)a;

[0038] In the formula, W represents the minimum resistance line, W = 0.32~0.6m.

[0039] In one possible implementation, the top surface of the transverse beam between the beams to be demolished is used as a construction platform, and blast holes are formed by vertical drilling.

[0040] In one possible implementation, controlling the tilting direction includes: for the tilting side, the lowest blast hole on the pier is 0.5m above the ground, and the highest blast hole is 1.40m above the ground; for the non-tilting side, the lowest blast hole on the pier is 0.5m above the ground, and the highest blast hole is 3.15m above the ground; the non-tilting side has a delayed detonation compared to the tilting side.

[0041] One or more technical solutions provided in the embodiments of this application have at least the following technical effects:

[0042] The directional blasting demolition method for bridge engineering defects provided in this application includes: cutting and separating the beam to be retained from the adjacent beam to be demolished, and cutting and separating the beams and slabs of the beam to be demolished; performing hydraulic blasting on the adjacent beams to be demolished; directional blasting of the piers and related crossbeams between the beams to be demolished; controlling the direction of collapse; detonating the adjacent beams to be demolished, the piers and related crossbeams between the beams to be demolished; and recovering the reinforcing steel and cleaning up the blast debris. It should be noted that this application follows the principles of "hydraulic blasting, isolation and vibration reduction, and directional collapse." Before the blasting operation, the beam to be demolished is cut and separated from the adjacent beams to be retained to ensure that the adjacent beams to be demolished and the beam to be retained are no longer adhered to each other after hydraulic blasting, thereby avoiding collateral damage to the beam to be retained or other structures caused by blasting vibration. Simultaneously, this application employs hydraulic blasting technology on the adjacent beams to be demolished, ensuring uniform destruction within the beam-slab-box chambers of these adjacent beams. This facilitates the "shattering" dismemberment of the adjacent beams, preventing large debris from impacting the retained beams or other structures. By controlling the dumping direction, this application avoids damage to surrounding infrastructure or injuries to construction workers during demolition, and also ensures that subsequent steel reinforcement recovery and debris removal are conducted away from residential areas. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A flowchart of a directional blasting demolition method for bridge engineering defects provided in this application embodiment;

[0045] Figure 2 A schematic diagram illustrating the cutting and separation of the beam to be retained and the adjacent beam to be demolished, provided in an embodiment of this application;

[0046] Figure 3 A schematic diagram of the arrangement of hydraulic blasting charges for the beam to be demolished, provided in an embodiment of this application. Figure 1 ;

[0047] Figure 4 A schematic diagram of the arrangement of hydraulic blasting charges for the beam to be demolished, provided in an embodiment of this application. Figure 2 ;

[0048] Figure 5 The diagram showing the layout of the blast holes for the bridge pier to be demolished is provided in the embodiments of this application.

[0049] Figure 6 This application provides a diagram showing the layout of the blast holes for the transverse beam to be demolished, as part of an embodiment.

[0050] Figure 7 This is a schematic diagram of blasting delay control provided in an embodiment of this application;

[0051] Figure 8 This is a schematic diagram of the blasting collapse process provided in an embodiment of this application;

[0052] Figure 9 A schematic diagram of a bridge engineering structure provided for an embodiment of this application.

[0053] Attached diagram labels: 1-wet joint; 2-explosive pack; 3-rope; 4-PVC pipe; 5-protective net; 6-blast hole; 7-sealed plastic bag; 8-wet joint. Detailed Implementation

[0054] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0055] In the description of the embodiments of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the embodiments of this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0056] This application provides a method for directional blasting demolition of damaged parts of bridge engineering, such as... Figures 1 to 9 As shown, the method includes S1 to S6:

[0057] S1: Cut and separate the beam to be retained from the adjacent beam to be demolished, and cut and separate the beams and slabs of the beam to be demolished;

[0058] S2: Perform hydraulic blasting on the adjacent beams to be demolished;

[0059] It should be noted that this application utilizes hydraulic blasting technology to generate uniform destructive effects in each space of the beam-slab box chamber, thereby "crushing" the beam to be demolished and avoiding damage to the structures to be preserved by large pieces of blasting debris generated by traditional blasting methods during the fall.

[0060] S3: Directional blasting to demolish the bridge piers and related transverse beams between the beams;

[0061] It should be noted that the piers and related transverse beams between the beams to be demolished in this application embodiment do not include the piers and related transverse beams shared by the beams to be retained and the adjacent beams to be demolished.

[0062] Directional blasting was used to demolish the piers and related transverse beams between the bridge sections to be demolished, while the corresponding superstructure beams were allowed to "fall vertically" under their own weight. For example... Figure 7 As shown, the upper beam between piers 29# and 31# collapsed vertically due to its own weight.

[0063] S4: Control the tilting direction;

[0064] It should be noted that when controlling the tilting direction of the bridge in this application, factors such as the site topography, living environment, public facilities, and flying rocks from blasting will be taken into account.

[0065] S5: Networked detonation to retain adjacent beams to be demolished, piers between beams to be demolished, and related transverse beams;

[0066] It should be noted that the detonation sequence of the bridge piers and related crossbeams adjacent to the beams to be demolished, and between the beams to be demolished, can control the direction of the blasting collapse and keep the blast site away from residential areas.

[0067] S6: Rebar recycling and slag removal.

[0068] It should be noted that this application, following the principles of "hydraulic blasting, isolation and vibration reduction, and directional collapse," involves cutting and separating adjacent beams to be demolished from those to be retained before the blasting operation. This ensures that the beams adjacent to the retained beams are no longer adhered to each other, thus preventing collateral damage to the retained beams or other structures caused by blasting vibrations. Simultaneously, the application of hydraulic blasting technology on the adjacent beams ensures uniform destruction within the beam-slab-box chambers of the adjacent beams, effectively dismembering them and preventing large debris fragments from impacting the retained beams or other structures. By controlling the dumping direction, this application avoids damage to surrounding infrastructure or injury to construction workers during the demolition, and also ensures that subsequent steel reinforcement recovery and debris cleanup are conducted away from residential areas.

[0069] In the embodiments of this application, such as Figure 2 As shown, the process involves cutting and separating the beam to be retained from the adjacent beams to be demolished, and further cutting and separating the beams and slabs of the beams to be demolished, including:

[0070] S11: The entire cross-section is transversely cut into the beam to be retained and the adjacent beam to be demolished, so that it becomes a simply supported beam structure.

[0071] It should be noted that the wet joint 8 between the beam to be retained and the adjacent beam to be demolished is cut transversely across the entire cross section.

[0072] S12: Cut the wet joint 1 between the beams to be dismantled along the longitudinal direction so that the beams and slabs of the beams to be dismantled are no longer bonded together.

[0073] It should be noted that this application uses hydraulic blasting technology to "crush" the adjacent beams to be demolished before directional blasting of the piers and related crossbeams between the beams to be demolished, thus creating an "isolation" between the structures to be demolished and the structures to be retained, thereby avoiding the risk of secondary damage caused by traditional blasting methods.

[0074] In this embodiment of the application, hydraulic blasting is performed on the adjacent beams to be demolished that are to be retained, including:

[0075] S21: Cut manholes and loading holes on the top of the beams adjacent to the beams to be demolished, where the beam to be retained is to be cut;

[0076] S22: Enter the beam-slab box chamber of the beam to be demolished adjacent to the beam to be retained, and seal its drainage holes with wooden plugs and waterproof materials;

[0077] S23: Use water pumps or fire trucks to inject water into the beam-slab box chambers of the beams to be demolished that are adjacent to the beams to be retained;

[0078] S24: Install and secure medicine pack 2.

[0079] In this embodiment of the application, the water pressure blasting of the adjacent beams to be demolished, which are to be retained, further includes:

[0080] S25: Install PVC pipe 4 on the charging hole;

[0081] S26: 5. Protective netting to be laid on the bridge deck.

[0082] Furthermore, in this embodiment, a protective net 5 is laid at the blasting site to reduce the impact of flying rocks from the blasting on the surrounding environment. The PVC pipe 4 can prevent water overflow from the box girder of the adjacent beam to be demolished after it has been filled with water.

[0083] In this embodiment of the application, installing and fixing the medicine pack 2 includes:

[0084] S241: The location of the explosive charge 2 is determined, and it is placed at the geometric center of the beam-slab box chamber of the beam to be demolished adjacent to the beam to be retained. The quantity of explosive charge 2 and the amount of explosive charge in a single explosive charge 2 are also determined.

[0085] S242: The explosive pack 2 and the digital electronic detonator are placed in a sealed plastic bag 7 and suspended in the box chamber of the beam to be demolished adjacent to the beam to be retained by the rope 3. The end of the rope 3 away from the explosive pack 2 is connected to the PVC pipe 4.

[0086] In this embodiment of the application, the formula for determining the quantity of medicine pack 2 is as follows:

[0087] N = (L - 2 × 1.5) / 1.2 (pieces);

[0088] In the formula, N represents the number of medicine packs 2, L represents the length of the adjacent beam to be dismantled, the distance between the edge medicine pack holes and the end of the beam to be dismantled is 1.5m, and the distance between adjacent medicine pack holes is 1.2m.

[0089] The formula for determining the amount of medicine in a single medicine packet 2 is as follows:

[0090] The amount of medicine in a single medicine packet 2 = Vq / N;

[0091] In the formula, V represents the masonry volume of the adjacent beam to be demolished, and q represents the explosive consumption per unit volume of reinforced concrete material, with a value of 1.0–2.0 kg / m³. 3 .

[0092] It should be noted that the rope 3 in this embodiment is a thin rope. The explosive charge 2 in this embodiment is an emulsion explosive.

[0093] Emulsion explosives and a digital electronic detonator are placed in a plastic sealed bag 7, making it into a spherical structure. Then, a thin rope is tied to the end of the spherical structure and connected to a PVC pipe 4, which is then connected to the piers and related crossbeam network between the beams to be demolished by directional blasting.

[0094] In this embodiment of the application, the piers and related transverse beams between the beams to be demolished by directional blasting include:

[0095] S31: Erecting scaffolding and construction platforms;

[0096] S32: Determine the location of the blast holes 6 for the bridge piers and related transverse beams;

[0097] S33: Drill 6 blast holes;

[0098] It should be noted that the embodiments of this application use a pneumatic drill to drill the blast hole 6.

[0099] S34: Install an explosive charge inside borehole 6 and seal it;

[0100] S35: Cover the blasting area with protective netting 5;

[0101] It should be noted that covering the blasting site with protective netting 5 can prevent the flying rocks generated after the blast from having an excessive impact on the surrounding environment.

[0102] S36: Dismantle scaffolding and evacuate personnel and machinery.

[0103] It should be noted that the blasting cuts of the piers between the beams to be demolished are set at their roots, which can increase the vertical drop height of the blast debris (including the upper beams), which is conducive to the secondary breaking of the blast debris and the recovery of the steel bars, and also reduces the difficulty of on-site construction.

[0104] In this embodiment of the application, the formula for determining the location of the blast holes 6 of the piers and related transverse beams between the beams to be demolished by directional blasting includes:

[0105] The spacing between the 6 blast holes is a = (1.2~1.5)W;

[0106] The spacing between the 6 rows of blast holes is b = (0.7~0.9)a;

[0107] In the formula, W represents the minimum resistance line, W = 0.32~0.6m.

[0108] It should be noted that, as Figure 5 and Figure 6 As shown, the formula for the drilling depth of the pier between the beams to be dismantled in this embodiment of the application is as follows:

[0109] h = (0.7 ~ 0.9)D;

[0110] h' = (0.7~0.9)D'

[0111] In the formula, D and D' represent the chord lengths of the borehole 6 and its relative position.

[0112] The formula for the drilling depth of the relevant transverse beams of the piers between the beams to be dismantled in this embodiment of the application is as follows:

[0113] h = (0.7~0.9)H;

[0114] In the formula, H represents the height of the transverse beam.

[0115] Furthermore, the type of explosive charge 2 is φ32 No. 2 rock emulsion explosive, and the value of q is 1.0~2.0kg / m 3 .

[0116] Furthermore, the formula for the amount of explosive used in borehole 6 is as follows:

[0117] Q = qv;

[0118] This application follows the principle of micro-differentiation in blasting demolition, allocates the amount of explosives for each blast hole in a direct proportion to the depth, and uses digital electronic detonators for sequential detonation.

[0119] Furthermore, the filling should be no less than the minimum resistance line.

[0120] In this embodiment, the top surface of the transverse beam between the beams to be dismantled is used as a construction platform, and a vertical drilling method is used to form blast holes 6 to facilitate construction.

[0121] In this embodiment of the application, controlling the tilting direction includes:

[0122] S41: For the tilting side, the lowest blast hole 6 on the pier is 0.5m above the ground, and the highest blast hole 6 is 1.40m above the ground;

[0123] S42: For the non-overturning side, the lowest blast hole 6 on the pier is 0.5m above the ground, and the highest blast hole 6 is 3.15m above the ground;

[0124] S43: Detonation is delayed on the non-tilting side compared to the tilting side.

[0125] It should be noted that when determining the delay time for adjacent blasting, sufficient time must be allowed for the instability of the tilting side, while preventing excessive delay that could cause compressive damage to the non-tilting side.

[0126] It should be noted that, as Figure 8 As shown, h2 is the distance from the highest point of the blast hole 6 on the collapsed pier to the beam, and h1 is the distance from the highest point of the blast hole 6 on the non-collapsed pier to the beam. Figure 7 It can be seen that the higher the tilting side, the more fragmented the slag becomes, making it easier to clean up later.

[0127] The existing elevated bridge connecting a highway has a superstructure consisting of prestressed concrete pre-simply supported and then continuously reinforced composite box girders. The span combination is 20m x 4, with a bridge deck width of 10m and 50cm crash barriers on both sides. The bridge deck consists of prestressed box girders, with the bottom slab, web, and top slab being thin-walled reinforced concrete structures. The wall thickness is mostly 180mm, with some sections reaching 250mm, and reinforcement ranging from φ10 to φ25. Each span has three box girders arranged side-by-side. The bridge deck is a 15cm thick double-layer reinforced concrete pavement. The substructure uses column piers with pile foundations. The abutments are column-type, with two piers per group connected by a crossbeam (1.3m high x 1.0m wide). The pier diameter is 1.6m, and the height ranges from 17.9 to 23m. Reinforcement consists of φ25 vertical bars and φ10 stirrups, using C30 concrete.

[0128] like Figure 9 As shown, continuous heavy rainfall triggered geological disasters in the bridge foundation, causing varying degrees of subsidence in the foundations of spans 28 to 32, resulting in bridge deck displacement. Specifically, the seismic blocks of the cap beams 28, 29, and 30 showed severe damage and cracking, essentially losing their restraining function. Piers 29 to 31 exhibited significant tilting, with the verticality of piers 29 and 30 severely exceeding limits. Pier 29 showed numerous annular cracks, and the transverse beams showed vertical and diagonal cracks. The lateral misalignment between the box girder at the top of piers 28 to 30 and the piers significantly worsened, and the cap beam at 29 detached from the beam body, losing its supporting function and posing a risk of instability, seriously affecting structural safety. Following continuous monitoring and consultation with relevant departments, it was decided to dismantle the beam body between piers 28 to 32 and piers 29, 30, and 31.

[0129] According to the on-site investigation, the surrounding environment of the object to be demolished is 60m east of the Han River, and the county road is under the west side of the bridge. It is adjacent to the mountain. There is a two-story residential building under the No. 28 pier, two prefabricated houses under the No. 30 and No. 31 piers, and an adobe house 54 meters away from the No. 31 pier. The terrain under the bridge is high in the west and low in the east, with a height difference of nearly 10 meters.

[0130] The bridge can be demolished using three methods: ① Manual demolition: This method is simple and does not require large equipment, but it is labor-intensive and has poor safety, taking 30 days and costing approximately 1 million yuan; ② Mechanical demolition: This method is faster than manual demolition and has lower technical requirements, but there are currently no large-scale mechanical equipment available for this purpose, taking 20 days and costing approximately 1.2 million yuan; ③ Demolition by blasting: This method has high technical requirements, but lower labor intensity and better safety, taking 7 days and costing approximately 800,000 yuan. Therefore, it is clear that the demolition by blasting method has significant cost and overall advantages.

[0131] The directional blasting demolition method for the damaged parts of a highway connecting viaduct is as follows:

[0132] (1) Cut and separate the beam to be retained from the beam to be demolished adjacent to the beam to be retained, and cut and separate the beams and slabs of the beam to be demolished.

[0133] It should be noted that the beams to be demolished and those to be retained should be completely separated to prevent "pulling" during the demolition process, thereby avoiding damage to the structures to be retained.

[0134] (2) Water pressure blasting of the beams of spans 28#~29# and 31#~32#.

[0135] ① Cut manholes and loading holes at the top of the beam;

[0136] ② Workers entered the beam and slab box chamber and sealed the drainage holes of the beams and slabs in spans 28#~29# and 31#~32# with wooden plugs and waterproof materials;

[0137] ③ Use water pumps or fire trucks to inject water into the beam-slab box chambers of spans 28#~29# and 31#~32#;

[0138] ④ Connect the PVC pipe 4 to the charging hole and lay the protective netting 5 on the bridge deck;

[0139] ⑤ Place the medicine pack 2 and the digital electronic detonator into a sealed plastic bag 7, making it into a spherical structure. Then tie a rope 3 to the end of the spherical structure. The end of the rope 3 away from the medicine pack 2 is connected to the PVC pipe 4.

[0140] ⑥ The beams of spans 28#~29# and 31#~32# were detonated via network connection.

[0141] Specifically, such as Figure 3 As shown, the length of the beam is L = 20m, and the number of explosive charges is (20 - 2 × 1.5) × 1.2 = 14.1 (charges), taking the value of 15. There are 3 box girders in each span, and the total number of explosive charges in the two spans is 90.

[0142] It should be noted that, as Figure 9 As shown, the beams between 28# and 29# and 31# and 32# in this application are blasted using hydraulic blasting technology. The two spans of beams 29# and 30# and 31# and the piers and related crossbeams in the middle area are in an "isolated" state. Their blasting and falling can avoid adverse effects on the 28# and 32# piers that are to be retained.

[0143] This application utilizes hydraulic blasting technology to generate uniform destructive effects in each space of the two spans of beam-slab box chambers, namely 29#~30# and 30#~31#, thereby "crushing" the beams to be demolished. This avoids the large blast fragments produced by traditional blasting methods from damaging the structures to be preserved during their fall.

[0144] It should be noted that, since the adjacent beams to be demolished are considered "damaged" structures with a certain degree of tilt, water injection could cause overflow, affecting the blasting effect. Therefore, this embodiment uses a longer PVC pipe 4 to prevent overflow after water injection into the beam-slab box chambers of the adjacent beams to be demolished. This embodiment also includes a protective net 5 at the blasting site, significantly reducing the negative impact of flying debris on the surrounding environment.

[0145] (3) Directional blasting of the lower three piers (29#, 30#, and 31#) and related transverse beams;

[0146] ① Erect scaffolding and construction platforms;

[0147] ② Determine the locations of blast holes 6 for piers 29#, 30#, and 31# and related transverse beams;

[0148] ③ Drill 6 blast holes;

[0149] ④ Install an explosive charge inside borehole 6 and seal it;

[0150] ⑤ Cover the blasting area with protective netting 5;

[0151] ⑥ Dismantle the scaffolding and evacuate personnel and machinery;

[0152] ⑦ The blasting of piers #29, #30, and #31 and related crossbeams was carried out via a network connection.

[0153] Specifically, such as Figure 5 As shown, the minimum resistance line of the pier is w = 40cm, the span is a = 40cm, the row spacing is b = 35cm, and the span depth is h = 1.2m.

[0154] like Figure 6 As shown, the minimum resistance line of the transverse beam is w = 35cm, the hole spacing is a = 40cm, the row spacing is b = 30cm, the hole depth is h = 0.95m, the diameter of all blast holes 6 is 0.4m, and the plugs for all blast holes 6 are 0.4m deep.

[0155] It should be noted that setting the blasting cut at the base of the pier can increase the vertical drop height of the blasting debris (including the upper beam), which is beneficial for the secondary breaking of the blasting debris and the recovery of the reinforcing steel, while also reducing the difficulty of on-site construction.

[0156] The transverse beam structure of this embodiment has a rectangular cross-section. The operator can use its top surface as a construction platform and use a vertical drilling method to form blast holes 6.

[0157] This application covers the blasting area with a protective net 5, which greatly reduces the impact of flying rocks from the blast on the surrounding environment.

[0158] (4) Control the tilting direction to detonate.

[0159] It should be noted that, as Figure 7 As shown, the box girders of spans 28#~29# and 31#~32# were all detonated using MS1 instantaneous detonators, the piers and cross beams on the overturned side were detonated using 1000ms digital detonators, and the piers on the non-overturned side were detonated using 1500ms digital detonators.

[0160] The 500ms delay time difference between adjacent blasts specified in this application is consistent with the actual situation on site. If it is too large, the preceding blast may cause the subsequent blast to fail to detonate; if it is too small, it may lead to poor directional blasting results.

[0161] like Figure 8 As shown, since h2 is much larger than h1, setting the blasting site on the h2 side can increase the vertical fall (or roll) height of the blasting debris (including the upper beam) and keep it away from blasting sites in residential areas.

[0162] (5) Rebar recycling and slag removal.

[0163] The directional blasting demolition method for bridge defects adopted in this embodiment achieves the safest demolition operation in the shortest time, and optimizes the construction period and construction cost.

[0164] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0165] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A method for directional blasting demolition of damaged parts of bridge engineering, characterized in that, include: The plan involves cutting and separating the beam to be retained from the adjacent beams to be demolished, and further cutting and separating the beams and slabs of the beams to be demolished, including: The entire cross-section of the beam to be retained and the adjacent beam to be demolished are cut laterally to transform them into simply supported beam structures. Cut the wet joints between the beams to be demolished longitudinally to prevent the beams and slabs from adhering to each other. Hydraulic blasting was carried out on the adjacent beams to be demolished; The directional blasting is intended to demolish the bridge piers and related transverse beams between the bridge sections, including: Erect scaffolding and construction platforms; Determine the locations of blast holes for the bridge piers and related crossbeams; Drilling blast holes; An explosive charge was installed inside the blast hole and then plugged. Cover the blasting area with protective netting; Dismantle the scaffolding and evacuate personnel and machinery; Controlling the tilting direction includes: For the tilting side, the lowest blast hole on the pier is 0.5m above the ground, and the highest blast hole is 1.40m above the ground; For the non-overturning side, the lowest blast hole on the pier is 0.5m above the ground, and the highest blast hole is 3.15m above the ground. The non-tipping side detonates later than the tipping side; The plan is to retain the adjacent beams to be demolished, the piers between the beams to be demolished, and the related transverse beams. Rebar recycling and slag removal.

2. The method for directional blasting demolition of damaged parts of bridge engineering according to claim 1, characterized in that, Hydraulic blasting was carried out on the adjacent beams to be demolished, including: Cut manholes and loading holes on the top of the beams adjacent to the beams to be demolished, where the beams to be retained are to be cut; Enter the beam-slab box chamber of the beam to be demolished adjacent to the beam to be retained, and seal its drainage holes with wooden plugs and waterproof material; Water pumps or fire trucks were used to inject water into the beam-slab box chambers of the beams to be demolished adjacent to the beams to be retained; Install and secure the medicine pack.

3. The directional blasting demolition method for bridge engineering defects according to claim 2, characterized in that, Hydraulic blasting of adjacent beams to be demolished, which are to be retained, also includes: Install a PVC pipe over the loading hole; Protective netting was laid on the bridge deck.

4. The directional blasting demolition method for bridge engineering defects according to claim 3, characterized in that, Install and secure the medicine pack, including: The location of the explosive charges is determined, and they are placed at the geometric center of the beam-slab box chamber of the beam to be demolished adjacent to the beam to be retained. The number of explosive charges and the amount of explosives in each explosive charge are also determined. The explosive pack and digital electronic detonator were placed in a sealed plastic bag and suspended by ropes in the box chamber of the adjacent beam to be demolished. The end of the rope furthest from the explosive pack was connected to a PVC pipe.

5. The directional blasting demolition method for bridge engineering defects according to claim 4, characterized in that, The formula for determining the number of medicine packets is as follows: N = (L - 2 × 1.5) 1.2 (pieces); In the formula, N represents the number of medicine packs, L represents the length of the adjacent beam to be dismantled, the distance between the outermost medicine pack hole and the end of the beam to be dismantled is 1.5m, and the distance between adjacent medicine pack holes is 1.2m. The formula for determining the amount of medicine in a single medicine packet is as follows: The amount of medicine in a single medicine packet = Vq / N; In the formula, V represents the masonry volume of the adjacent beam to be demolished, and q represents the explosive consumption per unit volume of reinforced concrete material, with a value of 1.0–2.0 kg / m³. 3 .

6. The method for directional blasting demolition of damaged parts of bridge engineering according to claim 1, characterized in that, Formulas for determining the locations of blast holes for piers and related transverse beams between bridge beams to be demolished by directional blasting include: The distance between blast holes, a = (1.2~1.5)W; The spacing between blast holes, b = (0.7~0.9)a; In the formula, W represents the minimum resistance line, and W = 0.32 to 0.6 m.

7. The method for directional blasting demolition of damaged parts of bridge engineering according to claim 1, characterized in that, The top surface of the transverse beam between the beams to be demolished was used as a construction platform, and blast holes were formed by vertical drilling.

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