CN109211041B - Reserved rock bank cofferdam blasting demolition method and application thereof - Google Patents
Reserved rock bank cofferdam blasting demolition method and application thereof Download PDFInfo
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- CN109211041B CN109211041B CN201811216389.8A CN201811216389A CN109211041B CN 109211041 B CN109211041 B CN 109211041B CN 201811216389 A CN201811216389 A CN 201811216389A CN 109211041 B CN109211041 B CN 109211041B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
- F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
- F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
- F42D1/08—Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
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- F42D3/04—Particular applications of blasting techniques for rock blasting
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Abstract
The invention relates to a method for demolishing a reserved rock bank cofferdam by blasting and application thereof. Compared with a one-time blasting demolition method, the demolition method solves the problems that the one-time blasting demolition preparation period of the rockbank cofferdam is long, the processing difficulty after blasting failure is high, and the cost for reliable safety protection measures to be adopted for protected buildings when the upstream surface of the rockbank cofferdam is not free, and the like, not only ensures the blasting quality, but also improves the construction efficiency.
Description
Technical Field
The invention relates to the technical field of blasting engineering, in particular to a method for demolishing a reserved rock bank cofferdam by blasting and application thereof.
Background
In the construction of hydroelectric engineering, the construction of projects such as diversion tunnels, diversion channels, tailrace tunnels and the like of hydropower stations needs to be carried out under the protection of cofferdams at inlets and outlets, and due to the limitation of topographic and geological conditions, the rock ridges reserved at the inlets and outlets are often used as temporary water retaining cofferdams, and after the construction of the protected projects is finished, the rock ridge cofferdams need to be dismantled. The common method is to uncover and thin the cofferdam to reduce the weight and demolish the cofferdam in a drilling and charging one-time blasting mode.
The precondition of the dismantling of the reserved rock bank in the mode is that the upstream surface and the back surface of the rock bank cofferdam have better free surfaces, and the detonation direction of the protected building (structure) can be towards the back surface or the upstream surface when the protected building (structure) is outside a dangerous area influenced by the rock bank cofferdam explosion. When a protected building (structure) is in a dangerous area affected by rockbank cofferdam blasting, the detonation direction is towards the upstream face, or when the upstream face is not exposed to the air, the detonation direction is towards the back face after reliable safety protection measures are taken on the protected building.
The one-time blasting demolition mode of the rock bank cofferdam has the advantages that the construction preparation period is long, the explosive blasting can be carried out only after all the drill holes are completely finished, the requirements on the drilling precision, the reliability of a blasting network and the blasting technical level are high, one-time success is ensured, and the processing difficulty is quite large. When the upstream face of the rock bank cofferdam is not free, blasting mode that the detonation direction faces the back face after reliable safety protection measures are taken on the protected building is high in investment cost, and difficulty in dismantling underwater safety protection facilities after cofferdam blasting is high.
Disclosure of Invention
The invention aims to solve the technical problem of providing a reserved rock bank cofferdam blasting demolition method and application thereof, in particular to a method for demolishing the reserved rock bank cofferdam by sectional blasting, which aims to solve the problems of long preparation period for demolishing the rock bank cofferdam by one-time blasting, high processing difficulty after blasting failure, high cost for taking reliable safety protection measures to the protected building when the upstream surface of the rock bank cofferdam is not free, and the like, thereby ensuring the blasting quality and improving the construction efficiency.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a reserved rock bank cofferdam blasting demolition method comprises the following steps:
step 1), determining a total blasting demolition scheme according to the structural form of the reserved rock bank cofferdam, the hydrological characteristics of a river and the surrounding environmental conditions;
step 2), measuring the shape of the reserved rock bank cofferdam, pre-dismantling the cofferdam under the condition of ensuring the safety and stability of the cofferdam by combining the relation of water level and flow corresponding to the river where the cofferdam is dismantled, reducing the elevation of the top of the cofferdam and thinning the weir body to form the most economical blasting dismantling section;
step 3), measuring the cofferdam after the pre-dismantling, drawing a plan view of the rock bank cofferdam, and drawing a cross-sectional view of the rock bank cofferdam at intervals of 5 meters;
step 4), determining the diameter D of a blast hole and the diameter D of explosive according to the condition of drilling equipment;
step 5), determining that blast holes are vertical holes, inclined holes or horizontal holes or a combination form of a plurality of blast holes according to the rock bank cofferdam body type, the surrounding environment condition and the construction condition;
step 6), according to the environmental conditions of the rock ridge cofferdam and the requirement of the blasting effect, calculating the unit consumption Q of the explosives, wherein the ratio of the linear meter loading quantity Q1 of the explosives to the unit consumption Q of the explosives is the area S borne by the blast hole, and according to the area S borne by the blast hole, calculating the corresponding hole distance a and rejection b;
step 7), carrying out blast hole plane arrangement and cross section arrangement design according to the plan view and the cross section view of the rock bank cofferdam;
step 8), calculating the single-hole explosive loading Q of the blast hole, and determining the explosive loading structure of the blast hole;
step 9), determining the position of a blasting opening and the detonation direction and the demolition sequence of a subsequent blasting section according to the position relationship between the rock bank cofferdam and surrounding buildings;
step 10), determining the length of a blasting opening and the length of blasting demolition segments according to the length of the rock bank cofferdam in the axial direction, and designing a blasting network according to the determined blasting direction;
step 11), blast hole position measurement lofting, and strengthening hole direction, hole inclination and hole depth control in the drilling process to ensure that the drilling precision meets the design requirements;
step 12), designing and constructing the safety protection of the building (structure) within the blasting influence range of the rock bank cofferdam;
step 13), drilling, charging, blocking, networking according to a blasting network diagram, detonating, and dismantling the open section of the rock bank cofferdam;
and step 14) repeating the step 13), and sequentially dismantling the subsequent blasting sections of the rock bank cofferdam.
The unit consumption q of the explosive in the step 6) is calculated according to a calculation formula of the unit consumption of the explosive in Sweden underwater blasting:
q＝q1+q2+q3+q4
wherein: q2 ═ 0.01 × h2
q3＝0.02*h3
q4＝0.03*h
In the formula: q is calculated explosive unit consumption, q1 is basic explosive unit consumption, q2 is water pressure increment unit consumption above an explosion area, q3 is explosion area covering layer increment unit consumption, q4 is rock expansion increment unit consumption, h2 is water depth, h3 is covering layer thickness, and h is step height.
The single-hole loading Q of the blast hole in the step 8) is calculated according to the following formula:
Q＝q.a.Wbottom.L
In the formula: q is the specific charge of explosive, a is the hole distance, WBottomL is the step height for the line of least resistance.
In the step 8), the blast hole charging structure comprises a continuous charging structure and a spaced charging structure, the continuous charging structure is characterized in that the main blast hole adopts continuous charging of explosives with the same diameter or combined continuous charging of explosives with different diameters, and the spaced charging structure is characterized in that pre-splitting holes adopt detonating cords to string spaced small-diameter cartridges to be fixed on a bamboo chip.
And (3) designing the blasting network, under the condition that the requirement on the network quasi-explosiveness is not high, filling a 15 th section of plastic detonator millisecond MS15 (detonator delay time 880MS) as an in-hole delay detonator in blast holes, using a 3 rd section of plastic detonator millisecond MS3 (detonator delay time 50MS) as an inter-hole transfer detonator between blast holes, locally adopting a 2 nd section of plastic detonator millisecond MS2 (detonator delay time 25MS) for carrying out interval, and using a 5 th section of plastic detonator millisecond MS5 (detonator delay time 110MS) as an inter-row detonator group for synthesizing the blasting network.
And step 10), designing the blasting network, namely, under the condition that the requirement on the quasi-explosiveness of the network is high, filling a high-precision 11 th-stage long-delay nonel detonator MS11 (detonator delay time 1000MS) into a blast hole to serve as an in-hole delay detonator, using a ground surface delay detonator with standard delay time of 17MS as an inter-stage detonator for an inter-hole booster detonator, partially adopting a ground surface delay detonator with standard delay time of 9MS for spacing, and using a ground surface delay detonator with standard delay time of 42MS as an inter-row detonator group to form the blasting network.
And 12), the safety protection design comprises the steps of increasing the blocking length of blast holes, covering a bamboo fence, a protective net or a sand-piling bag on a blasting body for active protection, controlling blasting flystones, binding bamboo gangboards, bamboo fences and the like on the surface of a protected object for passive protection, shielding the flystones, arranging a bubble curtain in front of a hydraulic gate, weakening the influence of blasting water shock waves on the gate, and controlling blasting vibration by controlling the single-ring blasting explosive quantity.
The invention discloses a reserved rock bank cofferdam blasting demolition method and application thereof, and the method has the following technical effects:
1) and demolish the rock bank cofferdam through adopting the segmentation blasting, drilling and blasting can alternate and go on, and line production has improved the efficiency of construction.
2) And the reserved rock bank cofferdam is removed by adopting sectional blasting, so that the blasting scale is reduced, the blasting network is simple, and the reliability is high.
3) The reserved rock bank cofferdam is dismantled through the sectional blasting, except for the fact that the blasting initiation direction of the opening section faces the upstream face, the axes of all the other sections of initiation directions are parallel to the downstream direction, the problem that the upstream face of the rock bank cofferdam does not have a free face is solved, the fact that the blasting initiation direction directly faces the backwater side of the cofferdam is avoided, and the safety risk of the protected building (structure) on the inner side of the rock bank cofferdam is reduced.
The hydraulic rock bank cofferdam is generally large in dismantling amount, in order to reduce the workload of underwater slag removal, reduce the influence of harmful effects of blasting and reduce the construction difficulty, the rock bank cofferdam mostly adopts a sectional, layered and staged dismantling scheme, the traditional method is that firstly, layered dismantling is carried out according to the water level change condition to reduce the height of rock banks, then, the inner side and the outer side of the rock bank cofferdam are sectionally dismantled through the stability analysis and calculation of a temporary water retaining rock bank cofferdam in the construction period, so that the rock bank square amount of the last blasting dismantling is reduced as much as possible, the inner side dismantling of the rock bank cofferdam adopts a conventional land blasting scheme, the blasted rock slag can be cleared on land, the favorable opportunity of the dry period can be used for blasting by the sectional dismantling outside of the rock bank cofferdam, and the blasted rock slag can be cleaned as much as far as possible, so that the outer boundary of the last blasting weir is changed from uncertain, the blasting effect is in a controllable state, and the blasting is removed for the last time.
The invention discloses a method for demolishing a reserved rock bank cofferdam by blasting, which is to demolish the rock bank cofferdam in a layered manner according to the water level change condition aiming at the conditions that the outer side of the rock bank cofferdam, namely the upstream side of the cofferdam, has no free face and the outer boundary of the cofferdam is uncertain and unclear, reduce the height of the rock bank, then blast at the proper position of the rock bank cofferdam to form a notch, and demolish the remaining cofferdam section by sectional blasting, wherein the blasting direction faces the notch along the axial direction of the cofferdam, and the demolition is. Compared with a one-time blasting demolition method, the demolition method solves the problems that the one-time blasting demolition preparation period of the rockbank cofferdam is long, the processing difficulty after blasting failure is high, and the cost for reliable safety protection measures to be adopted for protected buildings when the upstream surface of the rockbank cofferdam is not free, and the like, not only ensures the blasting quality, but also improves the construction efficiency. The invention relates to a method for demolishing a reserved rock bank cofferdam by blasting, which belongs to individual cases in the embodiment, but is also suitable for demolishing the diversion tunnel outlet cofferdam, the diversion open channel outlet cofferdam and other tailrace tunnel outlet cofferdams without instant diversion requirements by blasting.
Drawings
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
fig. 1 is a schematic plan view of the preserved rock bank cofferdam and the surrounding environment of the present invention.
FIG. 2 is a cross-sectional view of the rock reserve and the tailgate of the present invention.
Fig. 3 is a schematic plan view of the preserved rock bank cofferdam and the blast holes.
Fig. 4 is a schematic view of the arrangement of the cross sections of the preserved rock bank cofferdam and the blast holes.
Fig. 5 is a schematic diagram of a main charge of the present invention.
FIG. 6 is a schematic diagram of the blasting network of the present invention.
In the figure: the device comprises a tail water gate platform 1, a tail water channel 2, a rock bank cofferdam 3, a rock slag material 4 on the water-facing side of the cofferdam, a rock slag material 5 which needs to be dug and removed on the water-facing side of an opening section of the cofferdam, an opening section 6 of cofferdam blasting, a concrete sub cofferdam 7, a blast hole 8, a tail water maintenance gate 9, a tail water hoist bent frame 10, a blast hole 11, a dividing section line 12, a normal charging section 13, a weakening charging section 14, a blocking section 15, a large-diameter explosive roll 16, a small-diameter explosive roll 17, a first initiating body 18, a second initiating body 19, a bamboo chip 20, a plastic detonating tube detonator 21, a blocking object 22, an inter-hole detonating detonator 23, an inter-row detonating detonator 24 and a detonating station 25.
Detailed Description
A reserved rock bank cofferdam blasting demolition method comprises the following steps:
step 1), determining a total blasting demolition scheme according to the structural form of the reserved rock ridge cofferdam, the hydrological characteristics of the river and the surrounding environment conditions.
And 2) measuring the shape of the reserved rock bank cofferdam, pre-dismantling the cofferdam by combining the water level flow relation corresponding to the river at the cofferdam dismantling period under the condition of ensuring the safety and stability of the cofferdam, reducing the elevation of the top of the cofferdam and thinning the weir body so as to form the most economical blasting dismantling section.
And 3) measuring the cofferdam which is pre-dismantled, drawing a plan view of the rock bank cofferdam, and drawing a cross-sectional view of the rock bank cofferdam at intervals of 5 meters.
And 4) determining the diameter D (mm) of the blast hole and the diameter d (mm) of the explosive according to the condition of the drilling equipment.
And step 5), determining that the blast holes are vertical holes, inclined holes or horizontal holes or a combination form of a plurality of blast holes according to the rock bank cofferdam body type, the surrounding environment condition and the construction condition.
Step 6), calculating the unit consumption q (kg/m) of explosive according to the environmental conditions of the rock bank cofferdam and the requirement of blasting effect3) The linear meter loading Q1(kg/m) and the specific consumption Q (kg/m) of the explosive3) The ratio of (a) to (b) is the area S (m) borne by the blast hole2) According to the area S (m) borne by the blast hole2) Calculating corresponding hole distances a (m) and rejecting b (m).
And 7), carrying out plane arrangement and cross section arrangement design of blast holes according to the plan view and the cross section view of the rock bank cofferdam.
And 8) calculating the single-hole explosive loading Q (kg) of the blast hole, and determining the explosive loading structure of the blast hole.
And 9) determining the blasting opening position and the detonation direction and the demolition sequence of the subsequent blasting section according to the position relation between the rock bank cofferdam and the surrounding buildings (structures).
And step 10), determining the length of a blasting opening and the length of blasting demolition segments according to the length of the rock bank cofferdam in the axial direction, and designing a blasting network according to the determined blasting direction.
Step 11), blast hole position measurement lofting, strengthening hole direction, hole inclination and hole depth control in the drilling process, and ensuring that the drilling precision meets the design requirements.
And step 12), designing and constructing the safety protection of the building (structure) within the rock bank cofferdam blasting influence range.
Step 13), drilling, charging, blocking, networking according to a blasting network diagram, detonating, and dismantling the opening section of the rock bank cofferdam.
And step 14) repeating the step 13), and sequentially dismantling the subsequent blasting sections of the rock bank cofferdam.
Example 1
Taking the example of dismantling the cofferdam reserved for the tail water of the Yunnan lanstang river black dragon hydropower station. The tail water outlet lock chamber of the underground powerhouse of the Wulong hydropower station is positioned on the right bank of the downstream of the dam, the tail water outlet cofferdam is in a type of 'reserved rock bank + concrete sub-cofferdam', the total length of the cofferdam is about 130m, the height of the reserved rock bank is 1816.00m, the top width is 3.0m, the upstream side slope of the cofferdam is an original side slope, the slope ratio of the downstream side slope is 1:0.3, the concrete sub-cofferdam is poured on the reserved rock bank to 1818.00m, the cofferdam is a gravity retaining wall type concrete cofferdam, the top width is 0.60m, the slope ratio is 1:0.6, the upstream end of the cofferdam is connected with the upstream left pier of the outlet of the No. 1 tail water tunnel, the downstream end of the cofferdam is connected with the right side slope of the outlet tail water channel of the No. 2 tail water tunnel, and.
The original rockbank cofferdam dismantling scheme is that rockbank slag on the water-facing side of the cofferdam is cleaned, the rock slag on the water-facing side of the cofferdam is removed by one-step blasting integrally in the 4 th month end in 2018 after the blasting free face is increased, then a construction road is filled outside the cofferdam due to the construction of fishing channel engineering, the rockbank cofferdam only has free faces on the top face and the back face of the cofferdam, but the back face of the cofferdam faces a tail water gate, the influence on the gate by the one-step blasting integrally is particularly large, and once the gate is deformed or lifted, the safety of an underground factory building is greatly threatened.
In order to ensure the safety of the tail water gate, the rock bank cofferdam dismantling process comprises the following steps:
1) firstly, as shown in fig. 1-2, according to the structural form of the preserved rock bank cofferdam, the position relation with surrounding buildings (structures) and the water level-flow relation of the river, determining the rock bank cofferdam overall blasting demolition scheme as a water filling segment blasting demolition scheme in the weir. The concrete sub-cofferdam 7 at the top of the rock bank cofferdam is firstly dismantled to form a drilling operation platform, then the stone slag materials 4 on the upstream side of the downstream section of the rock bank cofferdam are dug and removed to form a blasting free face, the downstream section of the rock bank cofferdam is blasted to the upstream side to form a notch, and the rest rock bank cofferdams are blasted and dismantled downstream in a segmented mode along the axial direction of the cofferdam.
2) According to the engineering progress requirement, the reserved rock bank cofferdam is arranged to be dismantled before 2018 years of flood, according to the tail water level-flow relation of underground powerhouses of the Wulong hydropower stations, the top of the cofferdam is determined to be lifted to 1816.50m, as shown in fig. 2, the rock bank cofferdam is firstly dismantled, namely the concrete sub-cofferdam 7 at the top of the rock bank cofferdam is dismantled, and the cofferdam is lowered to 1816.50 m.
3) And as shown in fig. 3, measuring after the cofferdam is dismantled in advance, drawing a plan view of the reserved rock bank cofferdam, dividing section lines at intervals of 5m, and respectively drawing section views of corresponding section lines by combining a topographic map and an excavation design map.
4) And as shown in fig. 4, according to the drawn section diagram, factors such as water filling in the cofferdam, drilling operation, convenience of blasting networking and the like are comprehensively considered, and the mode that the blast holes are arranged in a rectangular shape and the divergent holes are drilled downwards from the top of the cofferdam is determined.
5) Calculating the unit consumption q (kg/m) of explosive3) The unit consumption of the underwater blasting explosive is calculated by the following Swedish underwater blasting explosive unit consumption calculation formula:
q＝q1+q2+q3+q4
wherein: q2 ═ 0.01 × h2
q3＝0.02*h3
q4＝0.03*h
In the formula: q is calculated specific charge, kg/m3(ii) a q1 is the unit consumption of basic explosive, kg/m3(ii) a q2 is unit consumption of water pressure increment above the explosion area, kg/m3(ii) a q3 is blast zone cover layer increment unit consumption, kg/m3(ii) a q4 is rock expansion increment unit consumption, kg/m3(ii) a h2 is water depth, m; h3 is the cover layer thickness, m; h is the height m of the bench.
6) According to the unit consumption of explosive q (kg/m)3) And the linear meter loading Q1(kg/m) of the explosive used, and calculating the area S (m) borne by the blast hole2) The linear meter loading Q1(kg/m) and the specific explosive consumption Q (kg/m) of the explosive3) The ratio of (a) to (b) is the area S (m) borne by the blast hole2) According to the area S (m) borne by the blast hole2) And calculating corresponding hole distances a (m) and rejection b (m), wherein S is a b.
7) Drawing a blast hole plane arrangement diagram according to the blast hole pitch a (m) and the rejection b (m), drawing a blast hole arrangement diagram of each section according to the drawn section diagram, wherein the blast hole plane arrangement diagram is shown in figure 3, the blast hole transverse section arrangement diagram is shown in figure 4, and the hole depth, the hole direction and the drilling angle of each blast hole are calculated on the blast hole transverse section arrangement diagram.
Calculating the single-hole loading Q (kg) of the blast hole according to the following formula:
Q＝q.a.Wbottom.L
In the formula, q is the unit consumption of explosive (kg/m3), and a is the hole distance (m); wBottomIs the minimum resistance line (m) and L is the step height (m).
8) Determining a charging structure of the blast hole: the presplitting hole adopts a detonating cord to bind a phi 32 cartridge on a moso bamboo sheet into a string-shaped spaced loading structure, and because the cross section of the rock ridge has the characteristic of narrow top and wide bottom, the upper blast hole has a large dense coefficient, and the lower blast hole has a small dense coefficient, if the same loading structure is adopted, the unit consumption of the upper explosive is inevitably overlarge, therefore, the main blasting hole adopts a combined continuous loading structure form, namely, the upper part of the blast hole is filled with phi 32mm emulsion cartridges (two sections are bound together), the linear loading of the explosive is 2.0kg/m, and the loading length is determined according to the actual hole depth; the middle part is provided with emulsified explosive rolls (3 sections are bound together) with the diameter of 32mm, the linear meter loading of the explosive is 3.0kg/m, and the loading length is 2.0m (when the hole depth is insufficient, the actual hole depth is determined); the bottom is provided with an emulsified explosive roll with the diameter of 70mm, the linear meter loading of the explosive is 4.2kg/m, and the loading length is determined according to the actual hole depth.
The main explosion hole charging structure is specifically shown in fig. 5, wherein 11 is a blast hole, 13 is a normal charging section, 14 is a weakening charging section, 15 is a blocking section, 16 is a large-diameter cartridge (phi 70mm), 17 is a small-diameter cartridge (phi 32mm), 18 is a first detonating body, 19 is a second detonating body, 20 is a bamboo chip or wood chip, 21 is a plastic detonating tube detonator, and 22 is a blocking object.
The normal charge section 13 is composed of a large-diameter cartridge 16 and a primary detonating body 18, and the primary detonating body 18 is composed of the large-diameter cartridge 16 and a plastic detonating tube detonator 21. The normal charging section 13 is used for continuous charging, wherein a section of large-diameter explosive roll 16 is provided with a double-shot high-section plastic detonating tube detonator 21 as a first detonating body 18, and the outside of a detonating tube leading-out hole is carefully fixed. The charging length is determined by calculation, and the diameter of the cartridge is about 20mm smaller than the diameter of the blast hole.
The weakening charge section 14 is composed of a small-diameter cartridge 17, a second detonating body 19 and bamboo chips or wood chips. The diameter of the small-diameter cartridge 17 is 32mm, and the cartridge is fixed by binding on bamboo chips or wood chips. The weakened charging section 14 is used for continuous charging, wherein a section of small-diameter explosive roll 17 is provided with a double-shot high-section plastic detonating tube detonator as a second detonating body 19, and the detonating tube leading-out hole is carefully fixed outside.
9) According to the relative positions of the rock bank cofferdam and the building (structure) to be protected, selecting the downstream section of the rock bank cofferdam farthest from the tail water gate as a blasting opening position, leading the blasting direction to face the riverbed outside the weir, blasting and removing the rest rock bank cofferdams in sections, leading the section length to be 15-20 m, leading the blasting direction to face the downstream direction along the axis of the cofferdam, and designing the blasting network according to the section length, wherein as shown in figure 6, a blasting network schematic diagram is shown, 11 is a blast hole, 2ms 15 (detonator delay time 880ms) plastic detonating tube detonators are arranged in the hole, 23 is an inter-hole detonating detonator, ms3 (detonator delay time 50ms) plastic detonating tube detonators are adopted, 24 is inter-row detonating detonators, ms5 (detonator delay time 110ms) plastic detonating tube detonators are adopted, and 25 is a blasting station.
Here, the 15 th stage plastic detonator MS15 (i.e., detonator delay time 880MS), the 3 rd stage plastic detonator MS3 (detonator delay time 50MS), the 2 nd stage plastic detonator MS2 (detonator delay time 25MS), and the 5 th stage plastic detonator MS5 (detonator delay time 110 MS).
10) The hole direction, the hole inclination and the hole depth are strictly controlled in the drilling process, the drilling precision is guaranteed to meet the design requirement, and a phi 90PVC pipe is inserted into the hole to the bottom of the hole after the final hole is drilled to be qualified, so that the blast hole is prevented from collapsing and blocking.
11) The shielding protection is carried out on buildings (structures) needing to be protected, and a double-row bubble curtain is arranged at the position 3m in front of the tail water gate so as to reduce the impact of the harmful effect of water shock waves on the tail water gate.
12) After drilling, charging and blocking are finished, networking is carried out according to a blasting network diagram, a sand bag is covered on a blasting body for active protection so as to reduce blasting scattered objects, after blasting, blasting operators enter a blasting site for inspection according to specified waiting time, and warning is removed after safety is confirmed.
13) And repeating the step 12) until the rock bank cofferdam is completely dismantled.
The invention discloses a method for demolishing a reserved rock bank cofferdam by blasting, which is mainly applied to demolishing the rock bank cofferdam to be demolished by blasting in a downstream section of the rock bank cofferdam to form a notch and demolishing the remaining cofferdam section by sectional blasting under the conditions that the inner side of the rock bank cofferdam is very close to a protected building and no blasting free face exists on the outer side of the rock bank cofferdam. Compared with a one-time blasting demolition method, the demolition method solves the problems that the one-time blasting demolition preparation period of the rockbank cofferdam is long, the treatment difficulty after blasting failure is high, and the cost for reliable safety protection measure investment on a protected building when the upstream surface of the rockbank cofferdam is not free from the free surface is high.
The application of the blasting demolition method of the preserved rock bank cofferdam on the blasting demolition of the preserved rock bank cofferdam, in particular to the application of blasting on the preserved rock bank cofferdam under the condition that the upstream face of the rock bank cofferdam has no free face and the protected building (structure) is within the dangerous area influenced by the blasting of the rock bank cofferdam, is difficult to realize by adopting integrated or other sectional blasting, because the one-time blasting demolition mode of the rock bank cofferdam has long construction preparation period, the blasting can be carried out only after all the drill holes are completely finished, and the requirements on the drilling precision, the reliability of a blasting network and the blasting technical level are high, the success of one time is ensured, otherwise, the processing difficulty is quite large; when the upstream face of the rock bank cofferdam is not free, blasting mode that the detonation direction faces the back face after reliable safety protection measures are taken on the protected building is high in investment cost, and difficulty in dismantling underwater safety protection facilities after cofferdam blasting is high.
The application of the blasting demolition method of the preserved rock bank cofferdam is to blast the preserved rock bank cofferdam, especially to blast the preserved rock bank cofferdam under the condition that the water facing surface of the rock bank cofferdam has no free surface and the protected building is within the dangerous area influenced by the blasting of the rock bank cofferdam. When the upstream face of the rock bank cofferdam is not free, blasting mode that the detonation direction faces the back face after reliable safety protection measures are taken on the protected building is high in investment cost, and difficulty in dismantling underwater safety protection facilities after cofferdam blasting is high.
Claims (8)
1. A reserved rock bank cofferdam blasting demolition method is characterized in that: the method comprises the following steps:
step 1), determining a total blasting demolition scheme according to the structural form of the reserved rock bank cofferdam, the hydrological characteristics of a river and the surrounding environmental conditions; determining the rock bank cofferdam overall blasting demolition scheme as a weir internal water filling segment blasting demolition scheme; firstly, dismantling a concrete sub-cofferdam (7) at the top of the rock bank cofferdam to form a drilling operation platform, then excavating and removing stone slag (4) on the water facing side of the downstream section of the rock bank cofferdam to form a blasting free face, blasting the downstream section of the rock bank cofferdam towards the water facing side to form a notch, and blasting and dismantling the remaining rock bank cofferdams towards the downstream along the axial direction of the cofferdam in a segmented manner;
step 2), measuring the shape of the reserved rock bank cofferdam, pre-dismantling the cofferdam under the condition of ensuring the safety and stability of the cofferdam by combining the relation of water level and flow corresponding to the river where the cofferdam is dismantled, reducing the elevation of the top of the cofferdam and thinning the weir body to form the most economical blasting dismantling section;
step 3), measuring the cofferdam after the pre-dismantling, drawing a plan view of the rock bank cofferdam, and drawing a cross-sectional view of the rock bank cofferdam at intervals of a certain distance;
step 4), determining the diameter D of a blast hole and the diameter D of explosive according to the condition of drilling equipment;
step 5), determining that blast holes are vertical holes, inclined holes or horizontal holes or a combination form of a plurality of blast holes according to the rock bank cofferdam body type, the surrounding environment condition and the construction condition; according to the drawn section diagram, the convenient factors of water filling, drilling operation and blasting networking in the cofferdam are comprehensively considered, and the mode that the blast holes are arranged in a rectangular shape and the divergent holes are drilled downwards from the top of the cofferdam is determined;
step 6), according to the environmental conditions of the rock ridge cofferdam and the requirement of the blasting effect, calculating the unit consumption Q of the explosives, wherein the ratio of the linear meter loading quantity Q1 of the explosives to the unit consumption Q of the explosives is the area S borne by the blast hole, and according to the area S borne by the blast hole, calculating the corresponding hole distance a and rejection b;
step 7), carrying out blast hole plane arrangement and cross section arrangement design according to the plan view and the cross section view of the rock bank cofferdam;
step 8), calculating the single-hole explosive loading Q of the blast hole, and determining the explosive loading structure of the blast hole;
step 9), determining the position of a blasting opening and the detonation direction and the demolition sequence of a subsequent blasting section according to the position relationship between the rock bank cofferdam and surrounding buildings; selecting a downstream section of the rockbank cofferdam farthest from the tailwater gate as a blasting opening position, wherein the blasting direction faces to a riverbed outside the weir, the rest rockbank cofferdams are demolished by subsection blasting, the length of each subsection is 15-20 m, the blasting direction faces to the downstream direction along the axis of the cofferdam, and blasting network design is carried out according to the blasting opening position;
step 10), determining the length of a blasting opening and the length of blasting demolition segments according to the length of the rock bank cofferdam in the axial direction, and designing a blasting network according to the determined blasting direction;
step 11), blast hole position measurement lofting, and strengthening hole direction, hole inclination and hole depth control in the drilling process to ensure that the drilling precision meets the design requirements;
step 12), designing and constructing the safety protection of the building within the rock bank cofferdam blasting influence range;
step 13), drilling, charging, blocking, networking according to a blasting network diagram, detonating, and dismantling the open section of the rock bank cofferdam;
step 14), repeating the step 13), and sequentially dismantling subsequent blasting sections of the rockbank cofferdam;
the blasting demolition method is used for the building which is not exposed to the air on the upstream surface of the rock bank cofferdam and is protected in a dangerous area affected by the blasting of the rock bank cofferdam.
2. The method for demolishing the cofferdam of the preserved karman according to claim 1, wherein: the unit consumption q of the explosive in the step 6) is calculated according to a calculation formula of the unit consumption of the explosive in Sweden underwater blasting:
q=q1+q2+q3+q4
wherein: q2 ═ 0.01 × h2
q3＝0.02*h3
q4＝0.03*h
In the formula: q is calculated explosive unit consumption, q1 is basic explosive unit consumption, q2 is water pressure increment unit consumption above an explosion area, q3 is explosion area covering layer increment unit consumption, q4 is rock expansion increment unit consumption, h2 is water depth, h3 is covering layer thickness, and h is step height.
3. The method for demolishing the cofferdam of the preserved karman according to claim 1, wherein: the single-hole loading Q of the blast hole in the step 8) is calculated according to the following formula:
Q=q.a.Wbottom.L
In the formula: q is the specific charge of explosive, a is the hole distance, WBottomL is the step height for the line of least resistance.
4. The method for demolishing the cofferdam of the preserved karman according to claim 1, wherein: in the step 8), the blast hole charging structure comprises a continuous charging structure and an interval charging structure, the continuous charging structure is characterized in that the main blast hole adopts explosive cartridges with the same diameter to continuously charge or explosive cartridges with different diameters to combine and continuously charge, and the interval charging structure is characterized in that the pre-split holes adopt detonating cords to string up and fix the small-diameter spaced explosive cartridges on the bamboo chips.
5. The method for demolishing the cofferdam of the preserved karman according to claim 1, wherein: and step 10), the blasting network is designed, under the condition that the requirement on the network quasi-explosiveness is not high, 15 th-section plastic detonator millisecond MS15 is filled in blast holes to serve as in-hole delay detonators, 3 rd-section plastic detonator millisecond MS3 serves as inter-hole booster detonators between the blast holes, 2 nd-section plastic detonator millisecond MS2 is locally adopted for spacing, and 5 th-section plastic detonator millisecond MS5 serves as an inter-row detonator group combined blasting network.
6. The method for demolishing the cofferdam of the preserved karman according to claim 1, wherein:
and step 10), the blasting network design is that under the condition that the requirement of the network quasi-explosiveness is high, high-precision 11 th-stage long-delay detonator MS11 is filled in blast holes to serve as in-hole delay detonators, ground surface delay detonators with standard delay time of 17MS are used as inter-hole transfer detonators between the blast holes, ground surface delay detonators with standard delay time of 9MS are locally used for carrying out interval, and ground surface delay detonators with standard delay time of 42MS are used as inter-row detonator groups to form the blasting network.
7. The method for demolishing the cofferdam of the preserved karman according to claim 1, wherein:
and 12), the safety protection design comprises the steps of increasing the blocking length of blast holes, covering a bamboo fence, a protective net or a sand-piling bag on a blasting body for active protection, controlling blasting flystones, binding a bamboo springboard and the bamboo fence on the surface of a protected object for passive protection, shielding the flystones, arranging a bubble curtain in front of a hydraulic gate, weakening the influence of blasting water shock waves on the gate, and controlling blasting vibration by controlling the single-ring blasting explosive quantity.
8. The method for demolishing the cofferdam of the preserved karman according to claim 1, wherein: and 3) drawing the cross-sectional view of the rock ridge cofferdam at intervals of 5 meters in the step 3).
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| CN111780638B (en) * | 2020-07-01 | 2023-07-21 | 中国水利水电第十六工程局有限公司 | Blasting demolition method for overflow dam segment of old dam |
| CN111765824B (en) * | 2020-07-01 | 2023-10-03 | 中国水利水电第十六工程局有限公司 | Method for removing old dam |
| CN112013731A (en) * | 2020-07-16 | 2020-12-01 | 中国电建集团中南勘测设计研究院有限公司 | Method for dismantling reserved rock ridge |
| CN113137898B (en) * | 2021-03-25 | 2022-10-21 | 中国能源建设集团广西水电工程局有限公司 | Cofferdam blasting demolition method based on combination of variable-linear-density charging and digital electronic detonator |
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