CN112945035B - Construction method for pre-splitting blasting excavation of middle and lower layers of diversion tunnel - Google Patents
Construction method for pre-splitting blasting excavation of middle and lower layers of diversion tunnel Download PDFInfo
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- CN112945035B CN112945035B CN202110357644.6A CN202110357644A CN112945035B CN 112945035 B CN112945035 B CN 112945035B CN 202110357644 A CN202110357644 A CN 202110357644A CN 112945035 B CN112945035 B CN 112945035B
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- 238000005422 blasting Methods 0.000 title claims abstract description 65
- 238000009412 basement excavation Methods 0.000 title claims abstract description 50
- 238000010276 construction Methods 0.000 title claims abstract description 37
- 239000011435 rock Substances 0.000 claims abstract description 51
- 238000000034 method Methods 0.000 claims abstract description 18
- 238000004880 explosion Methods 0.000 claims description 58
- 238000005336 cracking Methods 0.000 claims description 46
- 239000010410 layer Substances 0.000 claims description 28
- 238000005553 drilling Methods 0.000 claims description 26
- 239000002360 explosive Substances 0.000 claims description 21
- 238000013461 design Methods 0.000 claims description 10
- 230000000694 effects Effects 0.000 claims description 9
- 230000000903 blocking effect Effects 0.000 claims description 8
- 239000000839 emulsion Substances 0.000 claims description 3
- 239000002344 surface layer Substances 0.000 claims description 3
- 238000009966 trimming Methods 0.000 abstract description 16
- 239000011159 matrix material Substances 0.000 abstract description 11
- 238000000926 separation method Methods 0.000 abstract description 5
- 239000004575 stone Substances 0.000 description 8
- 238000005474 detonation Methods 0.000 description 6
- 210000003462 vein Anatomy 0.000 description 6
- 239000002893 slag Substances 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 239000004927 clay Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000003814 drug Substances 0.000 description 3
- 239000010438 granite Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- 238000009933 burial Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000003416 augmentation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052626 biotite Inorganic materials 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
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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
- F42D3/00—Particular applications of blasting techniques
- F42D3/04—Particular applications of blasting techniques for rock blasting
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/20—Hydro energy
Abstract
The invention discloses a method for excavating a middle-lower layer pre-splitting blasting of a diversion tunnel, and belongs to the technical field of hydraulic and hydroelectric engineering. The construction method for the lower layer pre-splitting blasting excavation in the diversion tunnel comprises the following steps of excavating a hole making platform, designing a pre-splitting hole, loading and connecting the pre-splitting hole, blasting the pre-splitting hole, designing a main blasting hole, loading and connecting the main blasting hole, and blasting the main blasting hole. The vertical hole of the lower half hole is pre-split for blasting, the two sides of the vertical hole are controlled to detonate, the rock body of the hole body is separated from the surrounding rock matrix, the flatness of the separation surface is high, the forming quality is excellent, the trimming operation is reduced, the over-digging of the hole body is well controlled, the backfill amount of permanent lining concrete is reduced, the engineering cost and the lining construction operation time are reduced, and the engineering progress is accelerated.
Description
Technical Field
The invention relates to the technical field of water conservancy and hydropower engineering, in particular to a method for excavating a lower layer of a diversion tunnel by pre-splitting blasting.
Background
Diversion tunnel refers to a tunnel for construction diversion purposes. At present, in hydraulic and hydroelectric engineering construction, because the diversion tunnel section is great, layering excavation is needed. And the upper half hole is excavated in a conventional excavation mode, and is pushed inwards, so that construction can be normally performed.
However, the traditional method adopted for excavating the side wall of the lower half hole is that firstly, a middle groove is formed, and then the side wall is excavated by light explosion.
Because the super-underexcavation caused by the horizontal light explosion hole of the side wall is difficult to control, and the side wall and the bottom plate have an included angle to form the underexcavation inevitably. And the outer flatness of the edge trimming excavation on the two sides is poor due to the ultra-underexcavation, the backfill amount of the permanent lining concrete is increased, the operation time of lining construction is correspondingly increased, the working efficiency is reduced, and the engineering cost is increased.
Meanwhile, the rock stratum of the cave body develops along the stratum, and is easy to slide along the stratum after excavation blasting. And vibration generated by multiple blasting is transmitted to the surrounding rock of the cavity, so that the danger of slumping and slumping is increased.
Disclosure of Invention
The invention aims to provide a construction method for pre-splitting blasting excavation of the middle and lower layers of a diversion tunnel, which is used for controlling the ultra-underexcavation of the tunnel body, improving the flatness, improving the excavation quality, accelerating the engineering progress, controlling the occurrence of the phenomena of inclined layer sliding of a side wall and falling along a structural surface during the excavation and improving the construction safety; so as to solve the problems existing in the prior art.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a diversion tunnel middle and lower layer pre-splitting blasting excavation construction method comprises the following steps:
s01: digging a hole forming platform, namely expanding and digging from the bottom surface of the upper half hole to two sides to form the hole forming platform;
s02: the design of the pre-cracking holes, namely arranging a plurality of pre-cracking holes along the axial direction of the tunnel at the position right below the side wall surface of the upper half hole; the drilling angle of the pre-cracking hole is 90 degrees and is perpendicular to the bottom plate, the depth of the pre-cracking hole is matched with the bottom plate, and the bottom of the pre-cracking hole is positioned on the bottom plate layer; the aperture and the interval of the pre-splitting holes are set according to the specific construction environment;
s03: charging and connecting pre-cracking holes, charging the pre-cracking holes, gradually increasing the interval size of the charging from the bottom of the holes to the mouth part, blocking the holes, and connecting a detonating tube with the pre-cracking holes;
s04: pre-cracking hole blasting, and checking blasting effect;
s05: the main explosion hole design is that a plurality of main explosion holes are arranged on the bottom surface of the upper half hole, and drilling holes are obliquely arranged towards the axial line side of the tunnel; the aperture and the interval of the main explosion holes are set according to the specific construction environment;
s06: charging and connecting the main explosion hole, charging the main explosion hole, and arranging a detonating tube to connect the main explosion hole;
s07: and (5) blasting the main blasthole, blasting, and checking the blasting effect.
Preferably, in step S01, the range of the hole-forming platform is set according to the working space of the equipment for excavating the pre-splitting hole.
Preferably, in step S03, rock emulsion explosive is used for the charge.
Preferably, in step S03, the pre-splitting holes are sequentially blasted from outside to inside along the axis of the tunnel; dividing the pre-cracking holes into a plurality of groups, and connecting the sub-explosion pipes to the main explosion pipe after the pre-cracking holes in the groups are connected through the sub-explosion pipes; the secondary detonating tubes in each group adopt the same specification, and the delay specifications of the secondary detonating tubes in each group are sequentially increased from outside to inside.
Preferably, in step S05, the main blastholes are drilled in a rectangular arrangement.
Preferably, in step S05, the main blasthole drilling is inclined at 80 degrees toward the tunnel axis side.
Preferably, in step S05, the main blasthole is designed to be divided once to the bottom or in stages; in the primary bottom design, the depth of the main explosion hole is matched with that of the bottom plate, and the hole bottom is positioned on the bottom plate layer; in the staged design, the depth of the main explosion hole is matched with the explosion bottom surface arranged at each stage, and the hole bottom is positioned on the stage explosion bottom surface layer.
Preferably, in step S06, the detonating tube is connected to detonate from the center to the periphery.
Preferably, the detonating tube is connected by interval segments, a main detonating tube is arranged at the central position of the top surface of the main detonating hole, the main detonating tube is sequentially connected from the center to the periphery and arranged on the auxiliary detonating tube of the main detonating hole, and the delay specification of the auxiliary detonating tube is sequentially increased from the center to the periphery.
Preferably, the range of the pore-forming platform is a range of 30 cm horizontally inwards from the side wall surface of the upper half hole, and a range of 2 m vertically upwards from the bottom surface of the upper half hole; in step S02, the diameter of the pre-split hole is 90 mm, the depth of the drilled hole is 12 m, and the row distance of the drilled hole is 0.8 m; the pre-splitting hole is filled with explosive in sections, wherein the sections are a hole bottom section and a middle section, the hole bottom section adopts 1 roll of 70mm explosive, the middle section adopts 42 rolls of 32 mm explosive, uncoupled explosive filling is carried out at intervals of 5-10 cm, and the hole opening is blocked by 2 meters; in the step S05, the main explosion hole is provided with a drilling hole diameter of 90 mm, the row distance between holes is 2-2.5 m, the drilling hole is deviated to the hole axis side by 80 degrees, and the hole depth is 12.7 m; in step S06, a roll of 70mm diameter is selected for continuous loading.
Compared with the prior art, the invention provides a diversion tunnel middle and lower layer presplitting blasting excavation construction method, which has the following beneficial effects:
1. according to the invention, the lower half hole vertical hole is subjected to presplitting blasting, so that the detonation at two sides is controlled, and the rock mass of the cave body is separated from the surrounding rock matrix; the flatness of the separation surface is high, the forming quality is excellent, and the trimming operation is reduced; moreover, the over-digging of the tunnel body is well controlled; the backfill amount of the permanent lining concrete is reduced, the engineering cost is reduced, the lining construction operation time is shortened, and the engineering progress is accelerated.
2. According to the invention, through separating the rock body of the cave from the surrounding rock matrix, when the rock body of the cave is blasted later, the transmission of vibration to the surrounding rock matrix is reduced, the phenomena of falling off and collapse of the side wall are better controlled, and the construction safety is improved.
3. According to the invention, the main explosion hole 5 is obliquely downwards arranged, so that the middle-lower half hole explosion can be completed at one time, and the engineering progress is further accelerated.
4. According to the invention, through the interval sectional connection of the main explosion holes 5, the blasting rocks are impacted and crushed under the action of external force, so that the large stones are reduced, the slag loading and transporting speed is increased, and the engineering progress is further accelerated.
The device has the advantages that the parts which are not involved in the device are the same as or can be realized by adopting the prior art, and the device controls the detonation at two sides to separate the rock body of the cave from the surrounding rock matrix through the pre-splitting blasting of the vertical hole of the lower half cave. The flatness of the separation surface is high, the forming quality is excellent, and the trimming operation is reduced; moreover, the over-digging of the tunnel body is well controlled; the backfill amount of the permanent lining concrete is further reduced, the engineering cost is reduced, the lining construction operation time is shortened, and the engineering progress is accelerated. Meanwhile, the rock body of the cave body is separated from the surrounding rock matrix, so that the transmission of vibration to the surrounding rock matrix is reduced during the subsequent blasting of the rock body of the cave body, the phenomena of falling off and collapse of the side wall are better controlled, and the construction safety is improved. The main explosion hole 5 is arranged obliquely downwards, so that the middle and lower half hole explosion can be completed at one time, and the engineering progress is further accelerated. The main blastholes 5 are connected in a segmented mode at intervals, blasted rocks are impacted and broken under the action of external force, large stones are reduced, slag loading and transporting speed is accelerated, and engineering progress is further accelerated.
Drawings
FIG. 1 is a schematic diagram of a diversion tunnel;
FIG. 2 is an enlarged schematic view of the structure shown at A in FIG. 1;
FIG. 3 is a schematic illustration of pre-crack hole arrangement and detonating tube connection;
FIG. 4 is a schematic diagram of a pre-split charge configuration;
fig. 5 is a schematic diagram of a main blasthole arrangement and a detonating tube connection.
In the figure: 1. the bottom surface of the upper half hole; 2. a pore-forming platform; 3. presplitting the hole; 4. the side wall surface of the upper half hole; 5. a main explosion hole; 6. a secondary detonating tube; 7. and a main detonation tube.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments.
In the description of the present invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," "outer," and the like indicate or are based on the orientation or positional relationship shown in the drawings, merely to facilitate description of the present invention and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
A diversion tunnel middle and lower layer pre-splitting blasting excavation construction method comprises the following steps:
digging a hole forming platform 2; designing a pre-cracking hole 3; charging and connecting the pre-cracking holes 3; blasting the pre-cracking hole 3; the main explosion hole 5 is designed; the main explosion hole 5 is filled and connected; the main blasthole 5 blasts, and checks the blasting effect.
S01: and excavating the hole forming platform 2, and expanding and excavating from the bottom surface 1 of the upper half hole to two sides to form the hole forming platform 2.
Please refer to fig. 1-2. In order to perform the pre-splitting blasting excavation of the middle and lower layers, in the process of performing the excavation of the upper half hole, or after the excavation of the upper half hole is completed, the upper half hole is excavated in an expanding manner to two sides at the intersection position of the upper half hole and the lower part, namely the horizontal plane position of the bottom surface 1 of the upper half hole, so as to be used as the pre-splitting blasting excavation operation space.
The range of the hole-making platform 2 is expanded, and the range is set according to the working space of the equipment for excavating the pre-cracking hole 3 so as to arrange the equipment and have enough operation space.
S02: the design of the pre-cracking holes 3 is that a plurality of pre-cracking holes 3 are distributed and arranged along the axial direction of the tunnel at the position right below the side wall surface 4 of the upper half hole; the drilling angle of the pre-cracking hole 3 is 90 degrees vertical to the bottom plate, the depth of the pre-cracking hole is matched with the bottom plate, and the bottom of the pre-cracking hole is positioned on the bottom plate layer; the aperture and the interval of the pre-splitting holes 3 are set according to the specific construction environment.
Please refer to fig. 3. The pre-cracking holes 3 are drilled in rows and are constructed through excavating equipment arranged in the hole-making platform 2. The pre-splitting holes 3 and the side wall surface 4 of the upper half hole are positioned on the same vertical plane, so that the lower part is matched with the upper half hole after being excavated. The distance between the adjacent pre-splitting holes 3 is matched and set according to the rock of the diversion tunnel, the selected explosive and the set aperture.
S03: the pre-cracking hole 3 is filled and connected, the space between the filling holes is gradually increased from the bottom to the mouth of the hole, the hole opening is blocked, and the detonating tube is connected with the pre-cracking hole 3. Rock emulsion explosive is used for charging.
Referring to fig. 4, the pre-splitting hole 3 is divided into a hole bottom section, a middle section and a blocking section, and the charging interval is gradually increased in the process of gradually upwards moving from the hole bottom section to the middle section; the blocking section is provided with clay for blocking.
Dividing the pre-cracking holes 3 into a plurality of groups, and connecting the sub-explosion tubes 6 to the main explosion tube 7 after connecting the pre-cracking holes 3 in the groups through the sub-explosion tubes 6; the secondary detonating tubes 6 in each group adopt the same specification, and the delay specification of each group of secondary detonating tubes 6 is sequentially increased from outside to inside; the main explosion tube 7 is arranged on the bottom surface 1 of the upper half hole and is led out outwards; the pre-cracking holes 3 are sequentially blasted in stages from outside to inside along the axis of the tunnel.
Please refer to fig. 3. By way of example, the pre-split holes 3 are equally divided into two groups, the pre-split holes 3 within each group being adjacent to each other; connecting a plurality of pre-cracking holes 3 in a group together by using a secondary detonating tube 6, and then connecting the secondary detonating tube 6 to a main detonating tube 7; the delay time of the outer group of the secondary detonating tubes 6 is smaller than that of the inner group of the secondary detonating tubes 6, and the outer side is pre-detonated.
S04: the pre-split hole 3 is blasted, and the blasting effect is checked.
S05: the main explosion holes 5 are designed, a plurality of main explosion holes 5 are arranged on the bottom surface 1 of the upper half hole, and drilling holes are obliquely arranged towards the axial line side of the tunnel; the aperture and the interval of the main explosion holes 5 are set according to the specific construction environment.
Preferably, the drilling of the main explosion hole 5 is inclined at 80 degrees towards the axis side of the tunnel, and the drilling of the main explosion hole 5 adopts rectangular arrangement.
S06: the main explosion hole 5 is filled and connected, the main explosion hole 5 is filled with the powder, and the powder is filled in a continuous powder filling mode; and a detonating tube is arranged to be connected with the main detonating hole 5.
Preferably, the detonating tube is connected by interval segments, the main detonating tube 7 is arranged at the central position of the top surface of the main detonating hole 5, the main detonating tube 7 is sequentially connected with the secondary detonating tube 6 arranged in the main detonating hole 5 from the center to the periphery, and the delay specification of the secondary detonating tube 6 is sequentially increased from the center to the periphery.
Referring to fig. 5, in an example, the main blastholes 5 are drilled in 4 rows, and each row is sequentially provided with 4 holes, 5 holes, 4 holes and 5 holes. The main detonating tube 7 is arranged in the center of the rectangle, and is led out and connected to the periphery, and the auxiliary detonating tube 6 is arranged in the main detonating hole 5. The time delay time from the detonating tube 6 increases from the center to the periphery, for example, the detonating tubes of MS3, MS5 and MS7 are selected in turn. The center is blasted first, and the blasting is diffused to the periphery in turn.
Compared with the conventional gun-discharging connecting mode, the intermittent sectional connection is adopted, so that the blasted rock is impacted and crushed under the action of external force, the large stone is reduced, and the slag loading and transporting speed is increased.
In step S05, the main blasthole 5 is designed to be divided once to the bottom or in stages; in the primary bottom design, the depth of the main explosion hole 5 is matched with that of the bottom plate, and the hole bottom is positioned on the bottom plate layer; in the staged design, the depth of the main explosion hole 5 is matched with the explosion bottom surface arranged at each stage, and the hole bottom is positioned on the stage explosion bottom surface layer. The method is particularly selected according to construction conditions, and if the required excavation surface depth is high, the rock stratum strength is high, the method can be selectively divided into multi-stage sequential downward construction.
S07: the main blasthole 5 blasts, and checks the blasting effect.
Preferably, the range of the hole forming platform 2 is a range of 30 cm horizontally inwards of the side wall surface 4 of the upper half hole, and the range of 2 m vertically upwards of the bottom surface 1 of the upper half hole; in step S02, the diameter of the pre-cracking hole 3 is 90 mm, the depth of the drilling hole is 12 m, and the row distance of the drilling hole is 0.8 m; the pre-splitting hole 3 is filled with explosive, the hole bottom section adopts 1 roll of 70mm explosive, the middle section adopts 42 rolls of 32 mm explosive, uncoupled explosive filling is carried out at intervals of 5-10 cm, and the hole opening is blocked by 2 meters; in the step S05, the main explosion hole 5 is provided with a drilling hole diameter of 90 mm, the row distance between holes is 2-2.5 m, the drilling hole is deviated to the hole axis side by 80 degrees, and the hole depth is 12.7 m; in step S06, a roll of 70mm diameter is selected for continuous loading.
In the construction of a certain hydropower station, the total length of a 1# diversion tunnel engineering tunnel body is 1522.614 meters, double curves are formed on a plane, the tunnel body section is in a gate shape, and the width and the height of the excavated section are 17 multiplied by 21 meters. The vertical burial depth of the diversion tunnel is mostly about 220 meters, the horizontal burial depth is about 230 meters, and the diversion tunnel is in a high-stress area; in the range of 100 meters at the entrance of the diversion tunnel, surrounding rock mainly comprises hard two clouds and two long granite, secondary biotite potassium long granite and pekoe vein development, and the rock mass is in a micro and new state and mainly comprises secondary block-shaped and block-shaped structures; since the segment is mostly placed in the stress augmentation zone, the ground stress is high. In the 1300 meter range of the cave body, surrounding rock is hard and is like spot black cloud potassium long granite, the pegmatic rock veins develop, the surrounding rock and the pegmatic rock veins are in welding contact, and the rock body is a block-shaped and integral structure; the section of tunnel is mainly located in a stress heightening zone, has high ground stress in a rock body and large intersection angle with a hole axis, and is unfavorable for surrounding rock stability. Small faults, joint cracks and local veins are randomly distributed in the surrounding rock, and when the small faults, the joint cracks and the local veins are combined disadvantageously, slow inclination cracks appear on the right side of a top arch in particular, microcrystalline veins are staggered, so that rock burst and slump fall blocks are caused.
In order to smoothly complete the engineering construction progress, the phenomena of inclined layer sliding, falling along a structural surface, collapse caused by rock burst and the like are well controlled during the excavation of the tunnel body. On one hand, the super-underexcavation of the tunnel body is controlled, the backfill amount of lining concrete stage is reduced, and the cost is reduced; on the other hand, the self-stabilization capability of the surrounding rock of the cavity is improved, the excavation flatness and the excavation quality are improved, and when the middle and lower layers of the lower half cavity are excavated, the diversion tunnel middle and lower layer pre-splitting blasting excavation construction method is adopted.
The 1# diversion tunnel is excavated into three layers of an upper half tunnel, a middle half tunnel and a lower half tunnel, in order to excavate the middle and lower layers, in the process of excavating the upper half tunnel, a hole forming platform 2 is excavated from the intersection part with the lower part, namely the plane layer of the bottom surface 1 of the upper half tunnel, to two sides. Planning a pre-cracking hole 3, and using a 100B drilling machine to form a hole, wherein the using space area of equipment is 2 meters by 30 cm; i.e. up to 2 meters and horizontally 30 cm, and the hole-making platform 2 is reamed. So as to ensure that enough space is formed for placing the drilling device, and the drilling holes are positioned right below the two side wall surfaces of the upper half hole and vertically downwards.
The pre-cracking hole 3 is formed, the upper half hole is dug, and the hole expanding and forming platform 2 is dug after the completion. In engineering implementation, 4 100B hydraulic drills are configured as pre-cracking hole 3 hole forming equipment according to a 5-meter daily footage plan of the lower half hole. The hole is formed and the hole depth is 12 meters and is matched with the excavation depth of the middle and lower half holes; the verticality is 90 degrees downwards; the hole spacing is 80 cm; the borehole diameter was 90 mm.
In the drilling construction, each hole point position is positioned by a total station, and checking is carried out by using a steel tape before drilling; after the drilling machine is in place, the verticality is controlled by an inclinometer and a plumb bob, so that the deflection of the hole site is prevented. After the drilling conditions are met, a field technician issues a drilling and perforating certificate. In the hole forming process, verticality is checked every 3 meters, deviation is found to be adjusted in time, and the hole bottom is ensured not to deviate, run or perforation is staggered. After each hole is formed, cleaning is carried out by using high-pressure water and a wind gun, sealing is carried out by using a gunny bag, and after each work is completed, a final hole certificate is issued on site.
The pre-cracking hole 3 is axially arranged along the shaft, and is arranged by testing and adjusting the blasting effect between 15 meters and 30 meters and selecting 20 meters as one section.
After the hole forming is completed, medicine is filled into the hole; the linear charge density is 0.7, the charge quantity is 7 kg/hole, and the blocking length is 2 meters. Specifically, the medicine filling intervals in each hole are discontinuous, and the medicine filling amount in a single hole is carried out according to the method that the interval size is gradually increased from the bottom to the mouth of the hole.
The pre-cracking hole 3 is arranged in a segmented way into a hole bottom section and a middle section. The first scheme is that 1 roll of explosive with the diameter of 70mm is adopted at the bottom of the hole, 42 rolls of explosive with the diameter of 32 mm are adopted at the middle section, uncoupled charging is carried out at intervals of 5-10 cm, and the blocking section of the hole clay is blocked by 2 meters. The scheme II is that 3 cartridges of 32 mm are adopted at the bottom of the hole, 43 cartridges of 32 mm are adopted at the middle section, uncoupled charging is carried out at intervals of 5-10 cm, and the blocking section of the hole clay is blocked by 2 meters.
Dividing the pre-cracking holes 3 into two groups, wherein the outer group adopts an MS1 detonating tube as a secondary detonating tube 6, and the inner group adopts an MS3 detonating tube as a secondary detonating tube 6; several slave detonators 6 are connected to a master detonator 7. By adopting different millisecond detonating tubes, the detonation is set to be two-stage detonation, and the outer side is detonated earlier than the inner side.
The pre-split hole 3 is blasted. And the two sides are detonated, so that the rock mass of the cave body is separated from the surrounding rock matrix, the flatness of the whole separation surface is high, and the secondary vibration caused by conventional trimming blasting is reduced. And when the subsequent blasting is carried out on the rock mass of the cave body which is separated from the parent body part, the transmission of vibration to the surrounding rock parent body is reduced to a certain extent, and the phenomenon of collapse after the side wall is formed is reduced.
And the main explosion hole 5 is designed, charged and exploded. The main explosion hole 5 is filled with explosive of 70mm, and the explosive quantity is set to reduce the blasting vibration damage to the side wall.
The main blasting holes 5 are formed into a section which is 10 meters deep along the axial direction of the tunnel, rectangular holes are generally adopted, and the main blasting holes can be properly adjusted according to the site. The charging adopts a continuous charging mode.
The blasting scheme of the main blasthole 5 is designed into a one-step forming and two-stage step excavation method.
When the excavation is carried out by one-step forming, the interval between the main blastholes 5 is 2 multiplied by 2 meters, 4 rows are arranged, and 4-6 main blastholes 5 are arranged in each row; the hole depth is 12-13 m, the plugging length is 2 m, and the normal charge of a single hole is 42 kg/hole, and the maximum charge of the single hole is 52.4 kg/hole.
Step excavation at two stages, wherein the interval between the main explosion holes 5 is 2 multiplied by 2.5 meters, 4 rows are arranged, and 4-5 main explosion holes 5 are arranged in each row; the depth of the hole is 6.5 meters, the plugging length is 1.5-2.0 meters, and the single-hole loading capacity is 25.5 kg/hole.
The detonating tube is connected with the detonating tube and detonates from the center to the periphery. The detonating tubes are connected in a segmented mode at intervals, the main detonating tube 7 is arranged at the center, and the detonating tubes MS3, MS5 and MS7 are sequentially used from the center to the periphery.
Compared with the conventional gun arrangement and connection mode, the interval sectional connection is adopted, so that the blasted rock is impacted and broken under the action of external force of blasted rock after blasting, the large stones are reduced, and the slag loading and transporting speed is increased.
Meanwhile, in the engineering construction, a comparison scheme is set, and two excavation schemes of ' first middle grooving, then trimming side walls at two sides ', first vertical hole presplitting and then middle primary blasting ' are adopted respectively.
The vertical hole pre-splitting blasting construction is more suitable through the actual achievement and the technical and economic comparison analysis.
Wherein, the scheme of trimming the two sides after the middle drawing groove is adopted: and the down-the-hole drill is adopted to carry out hole forming of the slotted hole, the pre-cracking trimming span at the two sides is about 3 meters, the large stone is more in excavation, and the secondary explosion-relieving amount is more. The trimming on two sides adopts a hand drill, and the height of each excavation is limited by the trimming construction requirement and is generally within 6 meters. So the middle layer excavation is carried out twice in time division, the blasting times are more in the same section of excavation range, and the excavation operation personnel can complete the excavation operation by circulating twice and running at night. Meanwhile, the hand drill is used for trimming, excavating and footage generally at about 3 meters, and the hand drill circulates twice a day. The levelness of the blastholes excavated by each trimming is difficult to control. And the control difficulty of 'one rod to one bottom' of the blast holes of each cannon is very high, and the situation of bedding development of the rock stratum of the tunnel body is combined, so that bedding sliding is easy to occur after excavation blasting to form over excavation. The method has the advantages that the trimming excavation on two sides is adopted, the appearance flatness is poor, the super-underexcavation is obvious, the backfill amount of the permanent lining concrete is increased, the cost of engineering is increased by analyzing the excavation cost of the concrete and the stone, the pouring amount of the concrete is increased, and the normal operation time of lining construction is prolonged to a certain extent.
Firstly, carrying out a vertical hole pre-splitting blasting scheme: the vertical hole pre-splitting blasting on two sides and the blasting hole on the middle part are both drilled by adopting a 100B drilling machine, the middle layer blasting is completed once, the pre-splitting blasting length is 20 m each time, the primary blasting length of the middle part is 10 m, the method is similar to open-cut blasting excavation, the cyclic operation is carried out every two days, and the excavation period is not delayed from the broaching trimming excavation. The vertical hole pre-splitting blasthole excavation flatness is high, the phenomenon of super-underexcavation is basically avoided, the concrete backfill caused by super-excavation is avoided, and the appearance quality is good. The stone excavation amount of 0.6 cubic per linear meter is increased only at the joint part with the upper layer, so that the visible overexcavation is realized, but the comprehensive excavation quality, concrete backfill, comparison in construction period and external knowledge on enterprise reputation and reputation are realized, and the pre-splitting blasting effect of the vertical holes of the two side walls is superior to that of the middle pull groove and the side walls for trimming and excavating.
The invention is mainly used in the field of diversion tunnels of hydropower stations, and can be used for reference in the lower layer excavation in the tunnel structures of underground plants and the like.
According to the invention, the lower half hole vertical hole is subjected to presplitting blasting, so that the detonation at two sides is controlled, and the rock mass of the cave body is separated from the surrounding rock matrix; the flatness of the separation surface is high, the forming quality is excellent, and the trimming operation is reduced; moreover, the over-digging of the tunnel body is well controlled; the backfill amount of the permanent lining concrete is reduced, the engineering cost is reduced, the lining construction operation time is shortened, and the engineering progress is accelerated. Meanwhile, the rock body of the cave body is separated from the surrounding rock matrix, so that the transmission of vibration to the surrounding rock matrix is reduced during the subsequent blasting of the rock body of the cave body, the phenomena of falling off and collapse of the side wall are better controlled, and the construction safety is improved. The main explosion hole 5 is arranged obliquely downwards, so that the middle and lower half hole explosion can be completed at one time, and the engineering progress is further accelerated. The main blastholes 5 are connected in a segmented mode at intervals, blasted rocks are impacted and broken under the action of external force, large stones are reduced, slag loading and transporting speed is accelerated, and engineering progress is further accelerated.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.
Claims (5)
1. The method for constructing the middle-lower layer pre-splitting blasting excavation of the diversion tunnel is characterized by comprising the following steps of:
s01: digging a hole forming platform (2), namely expanding and digging from the bottom surface (1) of the upper half hole to two sides to form the hole forming platform (2);
s02: the design of the pre-cracking holes (3) is that a plurality of pre-cracking holes (3) are distributed and arranged along the axial direction of the tunnel at the position right below the side wall surface (4) of the upper half hole; the drilling angle of the pre-cracking hole (3) is 90 degrees vertical to the bottom plate, and the depth is matched with the bottom plate; the aperture and the interval of the pre-splitting holes (3) are set according to specific construction environments;
s03: the method comprises the steps of filling and connecting pre-cracking holes (3), filling the pre-cracking holes (3), gradually increasing the interval size of filling from the bottom of the holes to the mouth, blocking the holes, and connecting a detonating tube with the pre-cracking holes (3);
s04: the pre-cracking hole (3) is blasted, and the blasting effect is checked;
s05: the main explosion holes (5) are designed, a plurality of main explosion holes (5) are arranged on the bottom surface (1) of the upper half hole, and drilling holes are obliquely arranged towards the axial line side of the tunnel; the aperture and the interval of the main explosion hole (5) are set according to the specific construction environment;
s06: the main explosion hole (5) is filled and connected, the main explosion hole (5) is filled with the explosive, and a detonating tube is arranged to be connected with the main explosion hole (5);
s07: blasting the main blasthole (5), blasting, and checking blasting effect;
wherein:
in the step S01, the range of the hole forming platform (2) is expanded and excavated according to the equipment working space for excavating the pre-splitting hole (3);
in the step S03, the pre-cracking holes (3) are sequentially blasted in stages from outside to inside along the axis of the tunnel; dividing the pre-cracking holes (3) into a plurality of groups, wherein after the pre-cracking holes (3) in the groups are connected through the secondary detonating tubes (6), the secondary detonating tubes (6) are connected to the main detonating tube (7); the secondary detonating tubes (6) in each group adopt the same specification, and the delay specification of each group of secondary detonating tubes (6) is sequentially increased from outside to inside;
in the step S05, the main explosion holes (5) are drilled in rectangular arrangement;
in the step S06, detonating tubes are connected and arranged to detonate from the center to the periphery;
the detonating tube is connected by adopting interval subsection connection, a main detonating tube (7) is arranged at the central position of the top surface of the main detonating hole (5), the main detonating tube (7) is sequentially connected from the center to the periphery, the auxiliary detonating tube (6) of the main detonating hole (5) is arranged, and the time delay specification of the auxiliary detonating tube (6) is sequentially increased from the center to the periphery.
2. The method for constructing the pilot tunnel middle and lower layer pre-splitting blasting excavation according to claim 1, wherein in the step S03, rock emulsion explosive is used for the charging.
3. The method for constructing the pilot tunnel middle and lower layer pre-splitting blasting excavation according to claim 1, wherein in the step S05, the main blasthole (5) is drilled to be inclined by 80 degrees toward the tunnel axis side.
4. The pilot tunnel middle and lower layer pre-splitting blasting excavation construction method according to claim 1, wherein in step S05, the main blasthole (5) is designed to be divided once to the bottom or in stages; in one-time bottom design, the depth of the main explosion hole (5) is matched with that of the bottom plate, and the hole bottom is positioned on the bottom plate layer; in the staged design, the depth of the main explosion hole (5) is matched with the explosion bottom surface arranged at each stage, and the hole bottom is positioned on the stage explosion bottom surface layer.
5. The method for constructing the pilot tunnel middle-lower layer presplitting blasting excavation according to claim 1, wherein the range of the pore-forming platform (2) is a range of 30 cm horizontally inwards of the side wall surface (4) of the upper half tunnel, and the range of 2 m vertically upwards of the bottom surface (1) of the upper half tunnel; in the step S02, the diameter of the drill hole of the pre-cracking hole (3) is 90 mm, the depth of the drill hole is 12 m, and the row distance of the drill hole is 0.8 m; the pre-splitting hole (3) is internally filled with explosive, the pre-splitting hole is divided into a hole bottom section and a middle section, the hole bottom section adopts 1 roll of 70mm explosive, the middle section adopts 42 rolls of 32 mm explosive, uncoupled explosive filling is carried out at intervals of 5-10 cm, and the hole opening is blocked by 2 meters; in the step S05, the main explosion hole (5) is provided with a drilling hole diameter of 90 mm, the row distance between holes is 2-2.5 m, the drilling hole is deviated to the hole axis side by 80 degrees, and the hole depth is 12.7 m; in step S06, a roll of 70mm diameter is selected for continuous loading.
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