A method for blasting brick chimney against each other under non-directional window condition
By employing a non-directional window blasting method for brick chimneys within a limited space, a rectangular blasting cut was designed and blast holes were symmetrically arranged, achieving counter-tilting and solving the problem of blasting efficiency under counter-collision of chimneys, thus improving construction safety and efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 贵州开源爆破工程有限公司
- Filing Date
- 2023-09-19
- Publication Date
- 2026-07-24
AI Technical Summary
In situations where there are multiple brick chimneys to be blasted within a limited space and the chimneys have a limited range of tilting, existing technologies struggle to effectively formulate blasting plans to improve blasting efficiency. This is especially true when there are opposing collisions between chimneys, highlighting the challenges of selecting and utilizing blasting resources to reduce vibration impact and enhance safety.
A blasting method under non-directional window conditions is adopted. By determining the center line of the chimneys, rectangular blasting cuts are designed and symmetrically set at the bottom of the opposite sides of the two chimneys. The blasting holes are evenly distributed, and a flexible protective layer is covered on the outside of the blasting cuts. The two chimneys are detonated at the same time to achieve opposite tilting and reduce the impact of vibration.
It effectively controlled ground vibration, reduced blasting debris, improved blasting efficiency, simplified subsequent cleanup work, avoided damage to surrounding facilities, and enhanced construction safety and efficiency.
Smart Images
Figure CN117190807B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of building demolition technology, specifically to a method for the opposite-direction collision blasting of brick chimneys under conditions of non-directional windows. Background Technology
[0002] With the advancement of urban construction, the iterative upgrading and transformation of old and new industrial facilities, and the increasing awareness of environmental protection in society, a large number of old industrial buildings such as chimneys and factories have gradually become abandoned, and a large number of tall structures such as chimneys and water towers have been demolished by blasting. The demolition blasting technology for tall structures such as chimneys is becoming increasingly mature. On the one hand, through extensive engineering practice, technicians and scholars have continuously summarized their experience, and blasting construction technology has been continuously optimized. The chimney blasting collapse method has also evolved from a single directional tilt to include double-cut opposite-direction folding, triple-cut bidirectional folding, and double-cut same-direction folding. On the other hand, the popularization of new operating equipment has promoted the emergence of new construction techniques. For example, electric core drilling water-jet drills, due to their ability to cut steel bars, have gradually begun to be used in blasting drilling of concrete chimneys and water towers. For the excavation of directional windows, "water-jet drill close-hole cutting" and "wire saw cutting" methods have also begun to appear, making the shape of directional windows more regular and refined. The popularization of long-arm operating platform equipment and the design of climbing formwork equipment have made the drilling and charging processes of high-level cuts safer and more convenient, providing equipment support for avoiding the complex bottom structure of tall structures such as chimneys.
[0003] The demolition of chimneys by blasting must consider both the chimney's own structure and the surrounding environment, as these two factors jointly determine the selection of the blasting scheme and the engineering layout of the blasting cut. There is considerable research and practice on chimney demolition by blasting. Yu Hongbing et al., through their experience with the blasting of a chimney at the Guiyang Tire Factory, analyzed that the central angle of the cut for heavy reinforced concrete chimneys could be reduced to 210° to decrease the risk of side-falling and recoil. Zhang Yingcai et al., analyzing the blasting effect of a 240-meter-high reinforced concrete chimney, concluded that the 3.9° deviation caused by the long-term weathering of the supporting cylinder on one side of the bottom centerline, resulting in insufficient support due to weaker strength on that side. Xing Guangwu et al. used blasting to excavate directional windows during the demolition of brick chimneys, reducing labor intensity and shortening excavation time. Shen Chaohu et al., through dimensional analysis and simulation experiments, predicted the distance of chimney debris and proposed that special attention should be paid to the problem of ground-contact debris caused by reinforced concrete chimneys when the collapse site is mud mixed with rocks. Wang Yu et al., using photography combined with strain measurement technology, explored the mechanical characteristics and failure process of chimney settling and fracture.
[0004] The blasting technology for brick chimneys is even more mature. In current practical blasting, mechanical methods for chiseling directional windows and pre-treating refractory bricks are basically no longer used. For example, when Xing Guangwu et al. demolished a thick-walled brick-concrete chimney, they used a combination of blasting and mechanical trimming to chisel triangular directional windows before the chimney was blasted. At the same time, the process of forming the directional window by blasting was used as the unit consumption for test blasting verification. Guo Xuebin et al. summarized the engineering practice of blasting chimneys without pre-treating the lining. They believed that when the lining layer is thin (12 cm for a single layer), ultra-deep blast holes should be used for the outer wall blast holes to make the center of the explosive charge close to the lining side and strengthen the charge. When the lining is thick (reaching 24 cm or multiple layers of lining), 1 to 2 rows of blast holes should be arranged from the outer wall and drilled to a certain depth of the lining. The inner and outer walls should be charged in sections or continuously. Test blasting should be used to verify whether the chimney lining can be destroyed.
[0005] However, the above discussions on blasting schemes for chimneys mainly focus on the details of directional tilting blasting schemes. There is little research on how to select and formulate blasting schemes, make full use of blasting resources, and improve blasting efficiency when there are multiple chimneys to be blasted in a limited space and the tilting range of the chimneys is limited; there are also few engineering examples to refer to. Summary of the Invention
[0006] The purpose of this invention is to provide a method for demolishing brick chimneys by head-on collision under conditions of no directional window, where two brick chimneys exist in a limited space and are capable of colliding head-on. This method aims to improve the efficiency of demolition by blasting.
[0007] A method for demolishing a brick chimney by impact blasting under non-directional window conditions includes the following steps:
[0008] Step 1: Determine the chimney wall structure. Use chimney drawings or through-hole probing to determine whether the bottom wall of the chimney has an inner lining structure and the thickness of the bottom wall.
[0009] Step 2: Determine the line connecting the centers of the two chimneys, and use this line as the collapse center line of the two chimneys;
[0010] Step 3: Determine the blasting incision. Use a non-directional window blasting incision. Design the blasting incision at the bottom of the opposite sides of the two chimneys. Set the blasting incision symmetrically along the collapse center line. The blasting incision is designed as a rectangle. The length of the blasting incision is 1 / 2 to 2 / 3 of the circumference. The height of the blasting incision is 1.5 to 3 times the thickness of the chimney wall at the blasting incision.
[0011] Step 4: Lay out the blast holes. Evenly lay out the blast holes within the blasting cut, extending from the outer wall of the chimney to the inner wall of the chimney.
[0012] 4-1: The spacing between blast holes and the distance between holes should be 0.5-0.6 times the thickness of the chimney wall;
[0013] 4-2: For unlined chimneys, the depth of the blast hole should be 0.67-0.70 times the thickness of the chimney wall; for lined chimneys, when the lining is thin, the blast hole should be appropriately deep so that the center of the explosive charge is close to the lining or the blast hole can be drilled directly into the lining. When the lining thickness is greater than 24cm, the 1-2 rows of blast holes in the blasting cut should be drilled all the way to the middle of the lining.
[0014] 4-3: The diameter of the borehole is 40-48 mm;
[0015] 4-4: The blasting unit consumption should be controlled above 0.8 kg / m³;
[0016] Step 5: Blasting protection, covering the blasting cut with a flexible protective layer;
[0017] Step 6: Detonation. The blast hole delay in both chimney blasting cuts is set to 0 ms, and both blasting cuts are detonated simultaneously.
[0018] The beneficial effects of this plan are:
[0019] (1) For two chimneys in a confined space, if the two chimneys are blasted separately, the vibration generated after the first chimney hits the ground will affect the second chimney. Since both chimneys are brick structures, the structure of the second chimney may be damaged under huge vibration, thereby increasing the safety and uncertainty of the tilting direction during the construction process of the second chimney. If the two chimneys are blasted at the same time and tilted in the same direction, the ground vibration will increase significantly because the two chimneys hit the ground at the same time. Therefore, both blasting methods need to limit the ground vibration. Currently, the way to limit the ground vibration is usually to lay a loose soil layer on the ground, which not only increases the cost, but also increases the amount of subsequent cleanup work.
[0020] (2) The opposing tilting collision fully utilizes the potential energy released during the tilting process of the two chimneys, which can cause the upper cylinder to disintegrate during the tilting process, reduce the rigid impact of the cylinder on the ground, and help control the collapse splash and impact vibration. Secondly, the opposing collapse method can make the collapsed body after the chimney is blasted more concentrated, which is convenient for subsequent slag removal construction and improves the efficiency of blasting demolition.
[0021] (3) Since the chimney is a brick structure, opening directional windows can easily damage the bottom structure of the chimney. Choosing a blasting method without directional windows and without pretreatment can also improve blasting efficiency. As for the situation where there are holes in the ground part of the chimney, the holes can be repaired by filling them with bricks.
[0022] Preferred Option 1: As a further optimization of the basic option, in step 4, the blast holes in the blasting cut are divided into upper blast holes, bottom blast holes and left and right side holes, with the unit consumption of the bottom blast hole > the unit consumption of the upper blast hole > the unit consumption of the left and right side holes.
[0023] Excessive energy consumption at the top and side boreholes will increase the area of blast debris. Therefore, increasing the energy consumption at the bottom borehole and decreasing the energy consumption at the top and side boreholes can reduce the coverage area of the debris. Secondly, in blasting with directional windows, the windows not only provide direction but also effectively prevent blast stress from damaging the remaining support wall. In this design, since blasting is performed without directional windows, the reduced charge at the side boreholes is to avoid excessive or out-of-bounds damage to the remaining support wall.
[0024] Preferred Option 2: As a further optimization of Preferred Option 1, in step 3, the circumference ratio of the blasting cut length is 0.55. This circumference ratio is preferred. If the blasting cut length is too large, it will lead to insufficient support at the bottom of the chimney. Insufficient support will cause the bottom support wall to collapse prematurely before the collapse trend is fully formed, which is not conducive to the chimney's orientation. On the other hand, if the blasting cut length is too small, it will affect the accuracy of the tilt direction. Therefore, both excessively long and excessively short blasting cuts will increase safety hazards.
[0025] Preferred Solution 3: As a further optimization of Preferred Solution 2, step 2 includes the following steps:
[0026] 2-1: Determine the intersection point O of the tangents of the two chimneys using the tangent method. The intersection point O is the point where the tangent of the front outer wall of the left chimney and the rear outer wall of the right chimney intersects the tangent of the rear outer wall of the left chimney and the tangent of the front outer wall of the right chimney at the same elevation at the bottom of the two chimneys.
[0027] 2-2: Draw lines from the intersection point O of the tangents to the central axis of the chimneys on the left and right sides respectively. The lines drawn are the center lines of the collapse of the two chimneys.
[0028] The absence of holes in the part of the chimney above ground makes it difficult to determine the center of the chimney. However, the center line can be effectively determined by using the tangent method to lay out intersecting lines.
[0029] Preferred Option 4: As a further optimization of Preferred Option 3, the bottom of the blasting cut is located within a height range of +0.4 to +1.0 m above the chimney ground elevation; this facilitates construction operations for workers.
[0030] Preferred Option 5: As a further optimization of Preferred Option 4, the boreholes in adjacent rows within the blasting cut are staggered; the staggered arrangement can enhance the uniformity of the borehole distribution.
[0031] Preferred Option Six: As a further optimization of Preferred Option Four, the blast holes on both sides of the top row of blast holes inside the blasting cut are eliminated; the blasting force generated by the blasting of the top row of blast holes is too large, which can easily cause the brick wall at the top of the blasting cut to collapse. By reducing the amount of explosives in the top row of blast holes, the range of influence of the blasting force can be reduced.
[0032] Preferred Option 7: As a further optimization of Preferred Option 6, an earthen embankment is built 3.5-4.5 m outside the blasting cut, with the embankment higher than the blasting cut; thus forming a second barrier against flying debris. Attached Figure Description
[0033] Figure 1 This is a schematic diagram of the environment surrounding the chimney during the blasting demolition in the embodiment.
[0034] Figure 2 This is a schematic diagram illustrating the centerline layout principle of the blasting scheme in the example embodiment;
[0035] Figure 3 This is a schematic diagram of the blasting cut in the blasting scheme of the embodiment;
[0036] Figure 4 A schematic diagram showing the cutout development and blast hole arrangement of chimney #1;
[0037] Figure 5 A schematic diagram showing the cutout development and blast hole arrangement of chimney #2;
[0038] Figure 6 A schematic diagram of the design for the detonation network;
[0039] Figure 7 Photo 1 shows the process of the chimney being toppled.
[0040] Figure 8 Photo 2 shows the process of the chimney being toppled;
[0041] Figure 9 This is a cross-sectional view of the drilling auxiliary positioning device in Embodiment 2;
[0042] Figure 10 This is a top view of the drilling auxiliary positioning device in Embodiment 2. Detailed Implementation
[0043] The following detailed description illustrates the specific implementation method:
[0044] The reference numerals in the accompanying drawings include: first flexible layer 11, airbag 12, positioning plate 13, box body 14, laser light source 15, power supply 16, protrusion 17, sliding column 21, spring 22, magnet 23, and second flexible layer 24.
[0045] Example 1:
[0046] This embodiment demonstrates a practical application of the blasting method described in this document. The chimney demolished by blasting is as follows:
[0047] The chimneys demolished by blasting in this embodiment were built in the last century and had been abandoned for many years. Chimneys #1 and #2 are 65 m and 60 m high, respectively, and are 40 m apart. Both are brick structures and need to be demolished in time to meet the land requirements of the construction project. Chimney #1 has an outer perimeter of 17.3 m and an outer diameter of 5.51 m at a bottom elevation of +1.0 m. The above-ground part of the chimney has no flue or ash outlet. The lower part of the chimney, about +8.0 m high, has a thickened wall. Drilling through the bottom revealed that the chimney has no internal lining and a lower wall thickness of 0.80 m. Chimney #2 has an outer perimeter of 12.75 m and an outer diameter of 4.06 m at the bottom. The above-ground part of the chimney has no flue or ash outlet. Drilling through the bottom revealed that the chimney also has no internal lining and a lower wall thickness of 0.70 m.
[0048] The surrounding environment is as follows:
[0049] The surrounding environment of the chimneys demolished by blasting was relatively good. The two chimneys were 40 meters apart. There was a nursery 46 meters northwest of chimney #1 and farmland 30 meters to the north. For chimney #2, there were high-voltage power lines and a water environment monitoring station 28 meters and 48 meters to the south, respectively; farmland 45 meters to the west; and a nursery 65 meters to the northwest. A schematic diagram of the surrounding environment of the chimneys is shown below. Figure 1 As shown.
[0050] The demolition plan is designed as follows:
[0051] Step 1: Through-hole probing
[0052] Before demolishing a chimney, it's essential to understand its wall structure. Since the brick factory had been abandoned for many years and no blueprints were available, and the chimney's above-ground portion lacked openings, it was impossible to determine the presence of an inner lining or insulation layer through the flue and ash outlet. Therefore, it was necessary to drill through-holes to investigate the chimney wall structure and thickness. After drilling, the bottom wall thickness of chimney #1 was found to be 0.80 m, and that of chimney #2 was 0.70 m. Neither chimney had an inner refractory brick lining or any interlayer structure at its base.
[0053] Step 2: Laying out the center line
[0054] In the implementation of this project, the centerline was first determined using the tangent method (either the string method or a total station). Figure 2 As shown, the contact point O is the intersection of the tangent lines between the west outer wall of chimney #1 and the east outer wall of chimney #2, which are located at a height of +1.0 m above the ground elevation of the two chimneys.
[0055] After the point of contact O is determined, lines are laid out from point of contact O to the central axis of chimneys #1 and #2 respectively. The laid lines are the center lines of the collapse of the two chimneys.
[0056] Step 3: Design of the blasting cut
[0057] The shape of the blasting notch directly determines whether a structure will collapse, while the location of the blasting notch determines the direction of collapse. After the blasting notch is formed and before the structure collapses, stress redistributes, and the supporting wall is divided into compression and tension zones. The line connecting the boundaries of the tension and compression zones on both sides is the neutral axis, and the perpendicular bisector of the neutral axis on the notch side indicates the direction of the chimney's collapse. Therefore, the design of the blasting notch is crucial.
[0058] like Figure 3 As shown, the blasting cuts for chimneys #1 and #2 are both designed as rectangular cuts, with a corresponding central angle of 198°. The length of the cut is 0.55 of the circumference. The height of the blasting cuts for chimneys #1 and #2 is 2.0 m, and the unfolded lengths of the cuts are 9.5 m and 7.0 m, respectively.
[0059] Step 4: Design of blasting parameters
[0060] Although the two chimneys lack refractory linings and insulation layers, their bottom sections have relatively thick walls. When drilling and blasting from the outer wall inwards, the arc-shaped inner walls at the bottom compress against each other under blast pressure, creating a tighter bond and lateral restraint. This results in greater resistance to blast stress compared to the outer wall. Therefore, when designing the borehole depth, the inner wall's resistance line should be slightly smaller than the outer wall's resistance line, and the explosive charge's center should be slightly offset towards the inner wall of the chimney. A borehole depth of 0.69 to 0.70 times the chimney wall thickness should be selected. The borehole diameter should be 40 mm to accommodate the explosive charge and to ensure sufficient energy transfer to the chimney wall.
[0061] Detailed blasting parameters for chimneys #1 and #2 are shown in Table 1, and the layout of blast holes within the cut is shown in Table 2. Figures 4-5 .
[0062] Table 1 Blasting Parameters
[0063] Table 1 Blasting parameters
[0064]
[0065] Step 5: Network Design
[0066] Both chimneys use the same digital electronic detonator initiation network. The borehole delay within the cuts of chimneys #1 and #2 is set to 0ms. Boreholes within the same chimney cut are connected in parallel using blasting busbars. Then, the two chimney initiation busbars are connected in parallel to a single detonator to ensure simultaneous detonation of both chimney cuts. The initiation network design is as follows: Figure 6 As shown.
[0067] Step 6: Protection against flying debris from blasting
[0068] The surrounding environment is relatively open, but there are overhead high-voltage lines around the two chimneys. The cut of chimney #1 faces the southwest water environment monitoring station, and the closest distance is only 85 m. Chimney #2 is only 45 m away from the water environment monitoring station to its south, but its cut faces the north chimney.
[0069] To prevent debris from damaging surrounding facilities during the blasting, protective measures were taken outside the blasting cut. Three layers of flexible carpet were used to secure the area outside the cut, covered with wire mesh. Additionally, since the blasting cut of chimney #1 directly faces the overhead high-voltage power line and the water environment monitoring station to the south, a 4.0-meter-high earthen embankment was built 4.0 meters outside the cut to form a second barrier against debris.
[0070] The blasting shall be carried out using this implementation plan, as shown in the attached document. Figure 7 , Figure 8 As shown, after the detonation, Chimney #1 broke at about one-third of its bottom section during the initial collapse phase, and Chimney #2 experienced a large-scale uneven collapse of the brickwork above the blast cut after the cut was formed. Both of these events had a certain impact on the direction of collapse, but still achieved the opposite collapse collision of brick chimneys under conditions of no directional window and no pretreatment.
[0071] Secondly, by choosing the opposing dumping blasting scheme, the collapsed body was relatively concentrated after the blast, which reduced the difficulty of subsequent debris removal work, improved efficiency, and shortened the construction period.
[0072] Example 2:
[0073] The reference numerals in the accompanying drawings include: first flexible layer 11, airbag 12, positioning plate 13, box body 14, laser light source 15, power supply 16, protrusion 17, sliding column 21, spring 22, magnet 23, and second flexible layer 24.
[0074] Example 2, based on the blasting scheme designed in Example 1, further restricts the drilling of the blast holes. Since the chimney wall is an arc surface, all blast holes within the blasting cut must point towards the center of the chimney to ensure a uniform distribution of blasting energy during blasting, thereby guaranteeing the accuracy of the chimney's collapse direction. However, because the chimney wall is an arc surface and a brick structure, it is impossible to guarantee a continuous and smooth arc surface. Drilling by operators alone can easily lead to blast hole deviation. To improve the accuracy of blast holes pointing towards the chimney center, the drilling scheme was optimized.
[0075] When drilling blast holes within a blasting cut, a blast hole drilling auxiliary positioning device is used for axial positioning of the blast holes. For example... Figure 9 , Figure 10As shown, the blast hole drilling auxiliary positioning device includes an airbag 12, a positioning plate 13 that can be connected to the airbag 12, and a positioning machine. The airbag 12 is elongated and made of elastic material (such as rubber) stitched together. Its cross-section can be circular, elliptical, or rectangular, preferably rectangular. The two ends of the airbag 12 are provided with straps, which can be used to connect the airbag 12 into a ring, thereby binding the airbag 12 to the outside of the chimney. A first flexible layer 11 (the flexible layer can be made of non-woven fabric or sponge) is attached to one side of the airbag 12, and the positioning plate 13 is fixed to the other side opposite to the first flexible layer 11.
[0076] The positioning plate 13 can be fixed to the airbag 12 by means of straps, buckles, etc., so that the positioning plate 13 and the airbag 12 can be detached. The positioning plate 13 is made of thin stainless steel sheet so that it has a certain deformation capacity. As the airbag 12 bends, the positioning plate 13 can also bend according to the corresponding arc. Locking rings are hinged on both sides of the positioning plate 13 along the length direction, so that the positioning plate 13 can be fixed to the airbag 12 by the cooperation of straps or buckles with the locking rings.
[0077] The positioning machine includes a rectangular box 14. A strip-shaped laser light source 15 is fixed in the middle of one side of the box 14. A power supply 16 electrically connected to the laser light source 15 is provided inside the box 14. A protruding rib 17 is fixed in the middle of the side adjacent to the side where the laser light source 15 is installed. The protruding rib 17 is arc-shaped. A first adsorption part and a second adsorption part are symmetrically installed on both sides of the protruding rib 17. The adsorption part includes a magnetic block and a spring 22 that connects the magnetic block to the box 14. The magnetic block and the spring 22 of the first adsorption part and the second adsorption part are the same size, but the spring coefficients of the springs 22 are different. The positioning machine is attached to the positioning plate 13 by a magnet, and a second flexible layer 24 is provided on the side of the magnetic block facing the positioning plate 13. A sliding column 21 parallel to the protruding ridge 17 is fixed on the box body 14. The magnetic block and spring 22 are sleeved on the sliding column 21. When the positioning machine is attached to the positioning plate 13, the protruding ridge 17 should be in the vertical direction. Under the action of the magnet and spring 22, the protruding ridge 17 is pressed against the surface of the positioning plate 13. Since the surface of the protruding ridge 17 is arc-shaped, the center line of the combined body is perpendicular to the positioning plate 13 under the adjustment of the spring 22. At this time, the laser light source 15 is perpendicular to the positioning plate 13 and can form a strip-shaped light spot on the ground.
[0078] When drilling blast holes within a blasting cut, follow these steps:
[0079] 1. The airbag 12 is tied to the lower part of the chimney and the first flexible layer 11 is in contact with the outside of the chimney. At the same time, the airbag 12 is located above the blasting cut and symmetrical along the collapse center line. A level can be used to assist in tying the airbag 12 so that the airbag 12 is as horizontal as possible.
[0080] 2. After the airbag 12 is secured, the airbag 12 is inflated by a compressor. Under the pressure of the air and the constraint of the chimney surface, the outer surface of the airbag 12 is a smooth arc surface.
[0081] 3. Fix the positioning plate 13 to the outer side of the airbag 12 so that the positioning plate 13 bends along the outer side of the airbag 12.
[0082] 4. Start drilling from top to bottom in columns. When drilling, position the drill bit at the blast hole to be drilled, fix the positioning machine on the positioning plate 13 above the blast hole to be drilled, and let the light spot emitted by the laser light source 15 be projected onto the drill bit, with one end of the light spot pointing to the center of the blast hole to be drilled; during the drilling process, try to keep the light spot on the center line of the drill bit.
[0083] 5. After drilling all the blast holes in the blasting cut, remove the positioning machine and positioning plate 13; during blasting, the airbag 12 remains attached to the chimney.
[0084] When the chimney was subjected to a counter-impact blasting according to the blasting scheme of Example 1, a large area of uneven brickwork above the blasting cut occurred after the blasting cut was formed. This was related to the brickwork structure of the chimney. Since brickwork structures are not as strong and stable as concrete structures, Example 2 further optimized the design based on Example 1. In Example 2, the airbag 12 not only serves to install the positioning plate 13 and the positioning machine, but also, because the airbag 12 is bound to the outside of the chimney before being inflated, forms a smooth arc surface on its outer periphery. During the blasting process, the airbag 12 is not removed. The inflated airbag 12 exerts a certain clamping force on the chimney body, thereby preventing a large area of brickwork above the blasting cut from collapsing.
[0085] Uneven collapse of the upper brickwork at the cut can also affect the direction of collapse, as can uneven distribution of blast holes. Because the surface of a chimney is curved, improper drill bit feed direction during drilling can lead to blast hole deviation, resulting in uneven distribution of blasting energy within the blast cut and affecting the direction of collapse. In Example 2, the laser light source 15 is used to position the drill bit feed direction, allowing for better control of the uniformity of blast hole distribution within the chimney wall, thus improving the stability of collapse direction control.
[0086] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.
Claims
1. A method for blasting brick chimneys by opposite impact under non-directional window conditions, characterized in that: Includes the following steps: Step 1: Determine the chimney wall structure. Use chimney drawings or through-hole probing to determine whether the bottom wall of the chimney has an inner lining structure and the thickness of the bottom wall. Step 2: Determine the line connecting the centers of the two chimneys, and use this line as the collapse center line of the two chimneys; 2-1: Determine the intersection point O of the tangents of the two chimneys using the tangent method. The intersection point O is the point where the tangent of the front outer wall of the left chimney and the rear outer wall of the right chimney intersects the tangent of the rear outer wall of the left chimney and the tangent of the front outer wall of the right chimney at the same elevation at the bottom of the two chimneys. 2-2: Starting from the intersection point O of the tangents, draw lines to the central axis of the chimneys on the left and right sides respectively. The drawn lines are the center lines of the collapse of the two chimneys. Step 3: Determine the blasting incision. Use a non-directional window blasting incision. Design the blasting incision at the bottom of the opposite sides of the two chimneys. Set the blasting incision symmetrically along the collapse center line. The blasting incision is designed as a rectangle. The length of the blasting incision is 1 / 2 to 2 / 3 of the circumference. The height of the blasting incision is 1.5 to 3 times the thickness of the chimney wall at the blasting incision. Step 4: Lay out the blast holes. Evenly lay out the blast holes within the blasting cut, extending from the outer wall of the chimney to the inner wall of the chimney. 4-1: The spacing between blast holes and the distance between holes should be 0.5-0.6 times the thickness of the chimney wall; 4-2: For unlined chimneys, the depth of the blast hole should be 0.67-0.70 times the thickness of the chimney wall. 4-3: The diameter of the borehole is 40-48 mm; 4-4: The blasting unit consumption should be controlled above 0.8 kg / m³; Step 5: Blasting protection, covering the blast cut with a flexible protective layer; binding airbags to the lower part of the chimney, with the airbags positioned above the blast cut and symmetrical along the collapse centerline. The airbags are made of elastic material sewn into long strips, with the cross-section set as circular, elliptical, or rectangular. The two ends of the airbags can be connected into a ring by straps. One side of the airbag is attached with a first flexible layer for contact with the outer wall of the chimney. After the airbags are bound, a compressor is used to supply air to the airbags to inflate them. Step 6: Detonation. The blast hole delay in both chimney blasting cuts is set to 0 ms, and both blasting cuts are detonated simultaneously.
2. The method for counter-collision blasting of brick chimneys under non-directional window conditions according to claim 1, characterized in that: In step 4, the blast holes within the blasting cut are divided into upper blast holes, bottom blast holes, and left and right side holes. The unit consumption of the bottom blast hole is greater than that of the upper blast hole, which is greater than that of the left and right side holes.
3. The method for counter-collision blasting of brick chimneys under non-directional window conditions according to claim 2, characterized in that: In step 3, the circumference ratio of the blasting cut length is 0.
55.
4. The method for counter-collision blasting of a brick chimney under non-directional window conditions according to claim 3, characterized in that: The bottom of the blasting cut is located within a height range of +0.4 to +1.0 m above the ground elevation of the chimney.
5. The method for counter-collision blasting of a brick chimney under non-directional window conditions according to claim 4, characterized in that: The adjacent rows of blast holes are staggered within the blasting cut.
6. The method for counter-collision blasting of a brick chimney under non-directional window conditions according to claim 4, characterized in that: Cancel the blast holes on both sides of the top row of blast holes inside the blasting cut.
7. The method for counter-collision blasting of a brick chimney under non-directional window conditions according to claim 6, characterized in that: An earthen embankment was built 3.5-4.5 m outside the blasting cut, with the embankment higher than the blasting cut.