CN114018112B

CN114018112B - Nuclear island and corridor foundation pit negative excavation blasting structure and blasting method

Info

Publication number: CN114018112B
Application number: CN202111220420.7A
Authority: CN
Inventors: 易意林; 李萌; 周益; 刘建木; 彭小松; 花强; 罗攀; 李汶锴; 郭永宽; 芦余送
Original assignee: China Nuclear Industry 24 Construction Co Ltd
Current assignee: China Nuclear Industry 24 Construction Co Ltd
Priority date: 2021-10-20
Filing date: 2021-10-20
Publication date: 2023-04-11
Anticipated expiration: 2041-10-20
Also published as: CN114018112A

Abstract

The invention discloses a negative excavation blasting structure and a blasting method for a nuclear island and corridor foundation pit. The blasting area of the annular corridor foundation pit is formed by enclosing an inner annular line and an outer annular line; the blasting area of the ring corridor foundation pit is divided into a plurality of blasting areas; a plurality of first pre-split holes are formed in the inner ring line at intervals, and a plurality of second pre-split holes are formed in the outer ring line at intervals; at least one row of first cut holes are formed between two adjacent blasting sections; a plurality of first main blasting holes are arranged in each blasting interval at intervals; the first pre-splitting hole, the second pre-splitting hole, the first cut hole, the second cut hole and the first main blasting hole are all provided with a charging section and a filling section. The invention can form ideal inner and outer circumferential cracks on the preset position of the rock foundation, and further can carry out main explosion for removing the rocks in the ring gallery, and simultaneously can quickly finish the construction operation of negative excavation of the ring gallery foundation pit of the nuclear island with high quality because of considering the technical requirements of vibration, tolerance and the like and adopting corresponding reasonable measures.

Description

Nuclear island and corridor foundation pit negative excavation blasting structure and blasting method

Technical Field

The invention relates to the technical field of nuclear power engineering, in particular to a negative excavation blasting structure and a blasting method for a nuclear island corridor foundation pit.

Background

In the prior art, the method for negatively excavating the circular corridor on the nuclear island has certain technical defects, such as: chinese patent publication No. CN101368812A discloses a nuclear island negative excavation gallery presplitting blasting method, which comprises the steps of: digging downwards at a selected position according to the island center elevation of the nuclear island, and reserving a reserved layer; drilling holes at equal intervals along the inner circumference and the outer circumference of the annular gallery respectively; filling a flexible material as a cushion layer at the bottom of the hole; three-section charging is carried out in a hole which is filled with a cushion layer and has a plugging depth at an orifice, the bottom is a reinforced charging section, the top is a weakened charging section, and the middle is a normal charging section; after the explosive is filled, the plugging depth of the orifice is plugged by conventional materials; and (4) detonating to form cracks along the inner circumference and the outer circumference of the annular gallery. However, the above patent is a presplitting blasting structure and method, that is, dense holes are drilled along the circumference of the outline of the nuclear island corridor for explosive blasting, so as to achieve the final purpose of ensuring the complete outline surface and flatness of the reserved surface after blasting on the inner and outer circumferences of the nuclear island corridor. This patent can only be used for the formation of nuclear island gallery presplitting gap, reaches the purpose that weakens the main part blasting to the destruction dynamics of gallery wall face, and can not be used for getting rid of the rock that need blast the excavation in the foundation ditch, can not reach the final purpose of foundation ditch excavation to it is when carrying out foundation ditch burden excavation, great blasting vibrations still can appear, influences building on every side.

Disclosure of Invention

The invention aims to provide a blasting structure and a blasting method capable of rapidly completing negative excavation construction of a nuclear island corridor foundation pit with high quality aiming at the defects in the prior art.

According to the negative excavation blasting structure of the nuclear island corridor foundation pit, a blasting area of the corridor foundation pit is formed by enclosing an inner ring line and an outer ring line;

the blasting area of the ring corridor foundation pit is divided into a plurality of blasting areas, and the plurality of blasting areas are sequentially divided into two first blasting areas, two second blasting areas, two third blasting areas and two fourth blasting areas along the direction close to the protection area;

a plurality of first pre-split holes are formed in the inner ring line at intervals, and a plurality of second pre-split holes are formed in the outer ring line at intervals;

at least one row of first cut holes are formed between every two adjacent blasting sections; a plurality of second cut holes are formed in the edge, close to the outer ring line, of each blasting section at intervals; a plurality of first main blasting holes are arranged in each blasting interval at intervals;

the first pre-splitting hole, the second pre-splitting hole, the first cut hole, the second cut hole and the first main blasting hole are all provided with a charging section and a filling section.

The blasting method for the negative excavation blasting structure of the nuclear island and annular corridor foundation pit comprises the following steps:

s1, detonating a first pre-crack hole to form an inner ring groove;

s2, detonating the first cut hole, and forming a vibration damping groove between two adjacent blasting sections;

s3, sequentially detonating the first main detonating holes of each blasting section to form grooves, wherein when the first blasting section is detonated, the second cut holes are detonated first, then the first main detonating holes on the second cut holes are detonated, and the first main detonating holes of each blasting section extend from the far-away protective zone to the near-to protective zone for detonation;

and S4, detonating the second pre-cracked hole to form an outer ring groove.

Further, will the gallery foundation ditch is planned to first thickness layer and second thickness layer along the direction of depth, first presplitting hole, second presplitting hole, first undermining hole, second undermining hole and first main hole of exploding all set up first thickness layer, the degree of depth of gallery foundation ditch is H, and first thickness layer is H, and H is greater than 1/2H.

Further, after the step S3 is completed, a main explosion area and an explosion area are arranged on the second thickness layer, a plurality of second main explosion holes are formed in the main explosion area at intervals, the explosion area is arranged around the main explosion area, a plurality of third cut holes are formed in the explosion area, the third cut holes and the second main explosion holes are detonated after powder charging is carried out, and then the step S4 is carried out, wherein the second main explosion holes are radial non-coupling powder charging.

Further, the initiation network of the main explosion area is set to delay initiation between holes.

Further, in the step S2, auxiliary holes are formed in the blasting area of the annular gallery foundation pit close to the edges of the inner annular line and the outer annular line.

Further, in the steps S2 and S3, a shallow hole blasting mode is adopted, the density coefficient of each blast hole is less than 1.5, the charging structures of the first cut hole, the first main blasting hole and the second cut hole are continuous charging, the hole array distance is less than the hole distance, the hole distance is less than the hole depth, and the length of the blocking section is more than 1/2 of the depth of each blast hole; the first cut holes are arranged into inclined hole double wedges, and the inclination angle of blast holes is 50-90 degrees.

Further, in step S3, the sequence of initiation of the plurality of blasting sections is as follows: a first blasting interval, a second blasting interval, a third blasting interval and a fourth blasting interval, wherein the detonation interval time is 75-150ms; and detonating at intervals in each blasting interval.

Further, in the step S1, the pitch of the first pre-split holes is 0.6-1.1m, and the row pitch is 2m; the first pre-splitting hole adopts a spaced charging mode and comprises a reinforced charging section, a normal charging section and a weakened charging section, wherein the length of the reinforced charging section is 1m, the interval between the cartridges of the normal charging section is 40-50cm, and the interval between the cartridges of the weakened charging section is 50cm.

Further, in step S4, the outer ring groove is formed by bidirectional energy-gathering blasting to form smooth blasting.

The invention can form ideal inner and outer circumferential cracks on the preset position of the rock foundation, and further can carry out main explosion for removing the rocks in the ring gallery, and simultaneously can quickly finish the construction operation of negative excavation of the ring gallery foundation pit of the nuclear island with high quality because of considering the technical requirements of vibration, tolerance and the like and adopting corresponding reasonable measures.

According to the invention, through a partition detonation mode, a vibration damping groove is formed between each blasting interval, each blasting interval is provided with a vibration damping hole, and the vibration damping holes and the vibration damping grooves have a combined control effect, so that the blasting seismic waves are weakened, and the safety of nuclear power operation facilities and equipment is ensured. The damping effect of the damping groove is mainly to realize effective separation and attenuation of explosion stress waves, so that the energy transmitted to a protection area is reduced, the propagation of the explosion seismic waves in adjacent areas behind the damping groove is obviously influenced by the damping groove, the damping groove has obvious reduction effect on the attenuation coefficient K value of the explosion seismic waves due to the separation effect of the damping groove on the explosion seismic waves, the diffraction effect of the stress waves at the bottom of the damping groove, the propagation effect of the stress waves on the wall of the damping groove and the like, the attenuation index alpha is also reduced to a certain extent, and the seismic waves in each explosion interval are mutually influenced, so that the damping effect on the explosion shock waves is realized, and meanwhile, the exploded rock stratum is subjected to bidirectional stress, so that the crushing effect is improved.

The method adopts the micro-difference deep hole blasting technology, reasonable delay time interval is not less than 50ms initially, the earthquake waves of blasting are weakened by mutually overlapping the earthquake effects generated by blasting of all holes, and the single explosive quantity is controlled to reduce the blasting vibration speed and the blasting vibration acceleration.

The small-resistance line width hole distance blasting technology (the dense coefficient of blast holes designed at present is not less than 1.5) is adopted, the blasting construction site selects the reasonable blasting minimum resistance line and the row distance, so that adjacent blasting funnels cannot be connected into a whole, the blasting face is correspondingly increased, the explosive energy is uniformly distributed in media in the blasting funnels, the blasting square quantity is increased, the blasting pile is concentrated, the reflection effect of stress waves of a free face is enhanced due to the small minimum resistance line, when the explosive stress waves are propagated to the free face, the surface media are crushed and move due to the generation of the reflection tensile stress, in the wide-hole distance blasting, the resistance lines of the explosive bag in all directions are uniform, the leakage time of high-pressure gas can be prolonged, the energy utilization rate of crushed rocks is improved, the explosive energy can be fully released, and the explosive energy is reduced and converted into the energy of seismic waves.

The method comprises the steps of performing presplitting blasting between a blasting place and a protection area to form presplitting gaps and presplitting surfaces, performing stone blasting after the presplitting blasting, and reflecting blasting seismic waves generated by the stone blasting when the blasting seismic waves are transmitted to the presplitting surfaces so as to weaken the propagation of the blasting seismic waves and quickly attenuate the blasting seismic waves, thereby ensuring the safe operation of a unit put into use in the protection area.

Drawings

FIG. 1 is a schematic diagram of a negative excavation blasting structure of a nuclear island corridor foundation pit according to the invention;

fig. 2 is a schematic diagram of a nuclear island corridor foundation pit negative excavation blasting structure after a vibration reduction groove is formed;

FIG. 3 isbase:Sub>A schematic cross-sectional view A-A of FIG. 2;

FIG. 4 is a schematic charge of a first pre-split hole of the present invention;

fig. 5 is a schematic structural view of a first cut hole of the present invention;

FIG. 6 is a schematic view of a first thickness layer dual initiation network of the present invention;

FIG. 7 is a schematic view of a single hole single-shot network in a second thickness layer of the present invention;

figure 8 is a schematic view of a single-hole multi-shot initiation network in a second thickness layer of the present invention.

1. Blasting area of the ring corridor foundation pit; 101. a first blasting interval; 102. a second blasting interval; 103. a third blasting interval; 104. a fourth blasting interval; 2. an inner loop; 201. a first pre-split hole; 3. an outer loop line; 301. a second pre-split hole; 4. a first cut hole; 5. a second cut hole; 6. a first main explosion hole; 7. a vibration damping groove; 8. a first thickness layer; 9. a second thickness layer; 10. a second main explosion hole; 11. auxiliary holes.

Detailed Description

The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.

As shown in fig. 1-3, the negative excavation blasting structure of the nuclear island corridor foundation pit of the invention is formed by enclosing a blasting area 1 of the corridor foundation pit by an inner ring line 2 and an outer ring line 3;

the blasting area 1 of the annular gallery foundation pit is divided into a plurality of blasting areas, and the plurality of blasting areas are sequentially divided into two first blasting areas 101, two second blasting areas 102, two third blasting areas 103 and two fourth blasting areas 104 along the direction close to the protection area;

a plurality of first pre-split holes 201 are formed in the inner ring line 2 at intervals, and a plurality of second pre-split holes 301 are formed in the outer ring line 3 at intervals;

at least one row of first cut holes 4 is arranged between two adjacent blasting sections in the first thickness layer 8; a plurality of second cut holes 5 are formed in each blasting section at intervals close to the edge of the outer ring line 3; a plurality of first main blasting holes 6 are arranged in each blasting interval at intervals;

the first pre-splitting hole 201, the second pre-splitting hole 301, the first cut hole 4, the second cut hole 5 and the first main explosion hole 6 are all provided with a charging section and a filling section.

The invention can form ideal inner and outer circumferential cracks on the preset position of the rock foundation, and further can carry out main explosion for removing the rocks in the ring gallery, and meanwhile, because the technical requirements of vibration, tolerance and the like are considered and corresponding reasonable measures are adopted, the construction operation of negative excavation of the ring gallery in the nuclear island can be rapidly and excellently completed.

The blasting method for the negative excavation blasting structure of the nuclear island corridor foundation pit comprises the following steps:

s1, detonating a first pre-crack hole 201 to form an inner ring groove;

s2, detonating the first cut hole 4 to form a vibration damping groove 7 between two adjacent blasting sections; each blasting interval is provided with one or two unequal damping grooves 7 towards the direction of the protection area to weaken the blasting wave, seismic waves in each blasting interval are mutually influenced, the blast shock wave in the fourth blasting interval 104 plays a role in inhibiting the blast shock wave in the third blasting interval 103, the second blasting interval 102 and the first blasting interval 101, and meanwhile, the blasted rock stratum is subjected to bidirectional stress, so that the crushing effect is improved, the interaction between rock masses is increased, and the rock masses are loosened.

S3, sequentially detonating the first main detonating holes 6 of each blasting section to form grooves, wherein when the first blasting section 101 is detonated, the second cut holes 5 are detonated first, then the first main detonating holes 6 are detonated, and the first main detonating holes 6 of each blasting section extend from a position far away from the protection area to a position close to the protection area for detonation; through the mode of regional initiation, form damping ditch 7 between every blasting interval, the damping effect of damping ditch 7 has mainly realized effective separation and weakening to the explosion stress wave, thereby reduce the energy of spreading to the guard space, the propagation of the earthquake wave of blasting in the adjacent region behind damping ditch 7 is obviously influenced by damping ditch 7, because damping ditch 7 to the separation effect of the earthquake wave of blasting, the diffraction effect of the stress wave at the bottom of damping ditch 7 and the propagation effect of the stress wave on the wall of damping ditch 7 etc., have obvious reduction effect to the attenuation coefficient K value of the earthquake wave of blasting, have certain reduction effect to attenuation index alpha.

The damping grooves form the undercut regions of the fourth, third and

second blasting sections

104, 103, 102, but the second undercut hole 5 is detonated first, forming the undercut region in the first blasting section 101.

And S4, detonating the second pre-cracked holes 301 to form outer ring grooves.

The ring corridor foundation pit is planned to be a first thickness layer 8 and a second thickness layer 9 along the depth direction, the first pre-split hole 201, the second pre-split hole 301, the first cut hole 4, the second cut hole 5 and the first main explosion hole 6 are all arranged on the first thickness layer 8, the depth of the ring corridor foundation pit is H, the first thickness layer 8 is H, and H is larger than 1/2H.

After the step S3 is completed, a main explosion area and an explosion area are arranged on the second thickness layer 9, a plurality of second main explosion holes 10 are arranged in the main explosion area at intervals, the explosion area is arranged around the main explosion area, a plurality of third cut holes (not shown in the figure) are arranged in the explosion area, the third cut holes and the second main explosion holes 10 are charged and then are detonated, and then the step S4 is performed, wherein the second main explosion holes 10 are charged radially and are not coupled.

The initiation network of the primary detonation zone is configured to initiate a delayed detonation between the holes.

In the step S2, auxiliary holes 11 are arranged at the edges, close to the inner ring line 2 and the outer ring line 3, of the blasting area 1 of the annular gallery foundation pit.

In the steps S2 and S3, a shallow hole blasting mode is adopted, the density coefficient of each blast hole is less than 1.5, the charging structures of the first cut hole 4, the first main blasting hole 6 and the second cut hole 5 are continuous charging, the hole array pitch is less than the hole pitch, the hole pitch is less than the hole depth, and the length of the blocking section is more than 1/2 of the blast hole depth; the first cut holes 4 are arranged in a slant hole double wedge shape with a blast hole inclination of 50-90.

In step S3, the sequence of initiation of the plurality of blasting sections is: a first blasting interval 101, a second blasting interval 102, a third blasting interval 103 and a fourth blasting interval 104, wherein the blasting interval time is 75-150ms; and interval detonating is adopted in each blasting interval. Thus, the micro-difference deep hole blasting technology is adopted, the reasonable delay time interval is not less than 50ms initially, the earthquake effect generated by blasting of each hole is mutually superposed to weaken the blasting earthquake wave, and the single-sound explosive quantity is controlled to reduce the blasting vibration speed and the blasting vibration acceleration.

In step S1, in order to reduce the disturbance of pre-splitting blasting on the side slope and ensure the stability of the side slope, when the current design slope of the side slope is relatively slow and the hole diameter is relatively small, the hole diameter of the first pre-split hole 201 in the engineering is easily deviated, the hole pitch of the first pre-split hole 201 may be set to 89mm, the row pitch is 2m, and the hole pitch is 0.6 to 1.1 m; the first pre-splitting hole 201 adopts a spaced charging mode and comprises a reinforced charging section, a normal charging section and a weakened charging section, wherein the length of the reinforced charging section is 1m, the interval between the cartridges of the normal charging section is 40-50cm, and the interval between the cartridges of the weakened charging section is 50cm.

In step S4, the outer ring groove may be formed by bidirectional energy-gathering blasting to form smooth blasting.

The present application is described below with respect to specific parameters:

presplitting blasting parameters in the step S1:

first pre-split hole 201 pore diameter: in order to reduce the disturbance of the presplitting blasting on the side slope and ensure the stability of the side slope, the design gradient of the current side slope is slow, and when the aperture is small, the position of a drilling hole is easy to shift, and the aperture of the presplitting hole of the engineering is determined to be 89mm.

First pre-split hole 201 pitch: in order to weaken the influence of blasting on the side slope, the hole pitch of the pre-splitting holes must be reasonably determined, generally 8-15 times of the diameter of the pre-splitting holes, the hole pitch of the pre-splitting holes is 0.6-1.1m, and the pre-splitting blasting area can be strongly weathered to 0.9m by moderate weathering and slight weathering.

Row spacing from adjacent holes: the row spacing of the first pre-cracked holes 201 and the adjacent holes is generally half of that of normal blast holes, if the first pre-cracked holes are far away, many rocks cannot be separated from parent rocks, secondary treatment is needed, and if the first pre-cracked holes are close to the parent rocks, the permanent slope is affected, many blasting cracks are formed, and the potential safety hazard of slope instability is formed. In this example, 2.0m was taken, and the adjustment was made appropriately during the construction.

First pre-split hole 201 length: the length of the first pre-splitting hole 201 is calculated according to the slope ratio and the designed excavation, most of rocks of the engineering are weathered, the first pre-splitting hole 201 is ultra-deep by 30cm, (in order to guarantee the integrity of the profile surface of the rock body, the strong impact of main hole blasting on the reserved rock surface is avoided, therefore, the pre-splitting surface must exceed the hole distribution range of the main hole blasting, the excess part is the ultra-long length of the pre-splitting), when the ultra-deep is less, the designed sideline underexcavation of the side slope is easy to cause, the structure sideline is arranged outside the bottom opening of the side slope by 1.5m, the construction channel is arranged within 1.5m, and the excavation of the bottom plate cannot be influenced when the pre-splitting of the side slope is ultra-deep by 30cm to the position below the bottom plate.

Thread loading density: in this embodiment, a thread-loading density of 0.286 to 0.33kg/m can be used.

As shown in fig. 4, the first pre-split hole 201 charge structure: in the engineering, the bottom of the first pre-splitting hole 201 is filled with the reinforced explosive section which is 1m, the middle of the first pre-splitting hole 201 is filled with the normal explosive section which is filled at intervals, and the distance between explosive cartridges is 40-50 cm. The distance between the weakening section and the medicine rolls is 50cm. The single explosive bag is 1/2 of the normal section, and the filling section is not filled with explosive about 1.4m above the pre-cracked hole. In construction, the detonating cord is connected with

The emulsion explosive is bound on the bamboo chips according to the requirements, and after the binding is finished, the explosive strings and the bamboo chips are filled into the pre-cracked holes and are filled. The strengthening medicine section is>

The emulsion explosive of (1).

S2 and S3 shallow hole blasting parameter determination

The blast holes referred to below refer to the first cut hole 4, the second cut hole 5, and the first pilot blast hole 6 provided in the first thickness layer 8.

When the depth of the blast hole is less than 1.5m, the blast hole is preferably constructed by adopting a small-bore diameter, the diameter of the blast hole is 76mm, and when the depth of the blast hole is more than 1.5m, the blast hole is preferably constructed by adopting a down-the-hole drill, and the diameter of the blast hole is 89mm.

When the depth of the blast holes is 0.3-0.5 m, the hole pitch of the blast holes is 0.4-0.5 m, the row pitch is 0.4-0.5 m, and the single-hole explosive loading is 0.028-0.056 kg; when the depth of the blast holes is 0.5-1.0 m, the hole pitch of the blast holes is 0.6-0.9 m, the row pitch is 0.5-0.7 m, and the single-hole explosive loading is 0.056-0.25 kg; when the depth of the blast holes is 1.0-1.5 m, the hole pitch of the blast holes is 1.3-1.5 m, the row pitch is 1.2-1.3 m, and the single-hole explosive loading is 0.7-1.3 kg; when the depth of the blast holes is 1.5-2.0 m, the hole pitch of the blast holes is 1.5-1.8 m, the row pitch is 1.4-1.6 m, and the single-hole explosive loading is 1.4-2.6 kg.

According to the experience of blasting excavation, the unit consumption of explosive is 0.45kg/m ³ . The blasting parameters can be determined as follows.

Shallow hole blasting parameter table (Table 2)

The blast holes of the shallow holes are arranged to ensure reasonable blast hole intervals, the blast holes are too thin, a plurality of blasting funnels can be formed after blasting, and overbreak and underexcavation are serious. Therefore, the row pitch is slightly smaller than the pitch of the holes; and arranging blast holes on the principle that the hole pitch is smaller than the depth of the blast holes.

The small-resistance line width hole distance blasting technology (the dense coefficient of the blast holes designed at present is not less than 1.5) is adopted, the reasonable blasting minimum resistance line and row distance are selected at the blasting construction site, the adjacent blasting funnels cannot be connected into a whole, the exposed surface after blasting is correspondingly increased, the explosive energy is uniformly distributed in media in the blasting funnels, the blasting square quantity is increased, the blasting piles are concentrated, the reflection effect of the stress wave of the free surface is enhanced due to the fact that the minimum resistance line is small, when the explosive stress wave is spread to the free surface, the reflected tensile stress is generated to enable the surface layer media to be broken and move, in wide-hole distance blasting, the resistance lines of the explosive bag are uniform in all directions, the leakage time of high-pressure gas can be delayed, the energy utilization rate of broken rocks is improved, the explosive energy can be fully released, and accordingly the explosive energy can be reduced and converted into the energy of seismic waves.

Further, shallow hole blasting has less single-hole explosive loading, and if the blast hole is blocked badly, the action time of detonation gas is short, so that the rock mass cannot be crushed fully. In order to obtain good results, the blast holes should be tightly plugged. The length of the plug is generally not less than 1/2 of the depth of the blast hole.

In the preferred example, shown in connection with figure 6, the detonation circuit is a multiple detonation circuit, since the detonation is zoned between each row of blastholes due to its proximity to the protected object.

Further, the parameters of the shallow hole slitting blasting are as follows

Shallow hole cut blasting parameter table (Table 3)

As shown in fig. 5, in the shallow hole blasting in which the damping trench 7 is formed, four rows of the first cut holes 4 may be included, which are arranged in an inclined hole double wedge shape, the hole inclination of the first cut holes 4 of the first row is 50 °, the hole inclination of the first cut holes 4 of the second row is 60 °, the hole inclination of the first cut holes 4 of the third row is 75 °, and the hole inclination of the first cut holes 4 of the fourth row is 90 °.

Second thickness layer 9 blasting parameter determination

Herein, theThe blast hole is arranged atOf a layer 9 of second thicknessA second main explosion hole 10 and a third undercut hole.

In the engineering, in order to protect the flatness of the bottom plate and weaken the influence of blasting construction on a horizontal infrastructure construction surface, a thickness layer more than one meter is reserved at the bottom of the second thickness layer 9, and during construction, the thickness layer is carefully organized and carefully controlled. And blasting excavation of the second thickness layer 9 adopts shallow hole blasting with small diameter of blast holes and small diameter of cartridges, stone ballast after blasting is loaded by a backhoe excavator, the stone ballast is transported and discarded by a dump truck, and underexcavation is mechanically crushed by an oil hammer.

Because the engineering has high requirement on the integrity of the bedrock of the bottom plate, the construction period is relatively tight, the second thickness layer 9 is excavated and is quickly constructed by adopting a high-performance hydraulic drilling machine, the depth of a blast hole is more than 1.5m, the diameter of the blast hole is 89mm, the emulsion explosive of a 70mm cartridge is leveled, the charging structure is shallow hole blasting of radial uncoupled continuous charging, the diameter of the blast hole is adopted within 1.5m, the cartridge is 32mm, the charging structure is shallow hole blasting of radial uncoupled continuous charging, and the blast hole is not an ultra-deep blasting scheme. After blasting, the ballast is loaded by a backhoe excavator, the dump truck is used for transporting and discarding the ballast, and the underexcavation adopts a construction scheme of mechanical crushing treatment by an oil hammer.

The blasting parameters of the second thickness layer 9 should be favorable for integrity of the bedrock and reduce damage of blasting to the bedrock. Minimum line of resistance 1.0m; the row spacing is 1.0m, the hole spacing is 1.0m, the depth of the explosive holes is 1.5m, the explosive holes are arranged according to quincuncial holes, the diameter of the explosive holes is 76mm, the filling length is ensured to be more than 1.0m, the diameter of the explosive roll is 32mm, every two explosives are arranged in parallel, the loading capacity of a single hole is within 0.7kg, the explosive holes are not over deep, and the unit consumption is 0.45kg/m ³ . And during actual construction, determining according to the test blasting experiment parameter result.

Table of parameters for the second thickness layer 9 plunge blasting (table 4) is as follows:

specifically, the second-thickness layer 9 blasting includes four rows of third cut holes arranged in an inclined-hole double wedge shape, the blast hole inclination angle of the first row of third cut holes is 45 °, the blast hole inclination angle of the second row of third cut holes is 45 °, the blast hole inclination angle of the third row of third cut holes is 75 °, and the blast hole inclination angle of the fourth row of cut holes is 90 °.

Furthermore, the underproduced section which is less than 30cm away from the designed elevation of the bottom plate is strictly forbidden to be treated by adopting a blasting method, and the underproduced section can be broken by adopting a hydraulic breaking head or chiseled by using a hand-held pneumatic pick or a sledge stick or a sledge hammer until the designed elevation is reached.

Second thickness layer 9 blasting circuit design

The detonation sequence and the detonation network have certain influence on the blasting effect, and the satisfactory mining effect can be obtained by selecting reasonable delay time intervals and the detonation sequence.

The millisecond delay interval time can be calculated by the formula deltat = kW,

wherein: k-coefficient relating to rock properties, structural configuration and blasting conditions, taking 15-25 under open blasting conditions

W-line of least resistance, m.

The millisecond delay interval time delta t = 75-125 MS is calculated, according to the non-electric millisecond detonator series in China, the delay time of the MS-13 section is 650MS, the delay time of the MS-4 section is 75ms, and the delay time of the MS-5 section is 110MS.

The foundation pit excavation adopts the detonating network of delay detonation in turn row by row, the groove detonating network detonates row by row along the trend of the groove, and according to the complexity of the surrounding environment, the detonating network of single-hole single-sound or in-hole subsection is adopted.

In an alternative embodiment, as shown in fig. 7, when a single-hole single-ring network is used, the same section of detonator, such as the MS-10 section in the hole, is installed in the hole, and the MS-2/3/5 section is adopted outside the hole for delaying, so as to form the single-hole single-ring network.

In other embodiments, as shown in FIG. 8, if the hole is filled with the explosive sectionally and alternately, MS-11/10 two-section detonators are arranged in the hole, MS-11 is arranged at the bottom of the hole, MS-10 is arranged at the upper part of the hole, and the length of the middle plug is more than 1.0m, so that a sectionalized network in the hole is formed.

In step S4, smooth blasting is formed by bidirectional energy-accumulating blasting to smooth the surface of the outer ring groove.

Blast result monitoring

In the present embodiment, 6 monitoring points are arranged, and the details of the monitoring points are as follows:

(1) 1 monitoring points (which simultaneously monitor vibration acceleration in horizontal radial direction, horizontal tangential direction and vertical direction) are arranged on the roofs of the 1 # LX and 2# LX plants closest to the blasting position, and the specific positions are the positions of the west center lines of the roofs of the 1 # LX and 2# LX plants.

(2) And 1 monitoring point (simultaneously monitoring vibration acceleration in horizontal radial direction, horizontal tangential direction and vertical direction) is arranged in a free field outside the edge of the No. 1 nuclear island plant (or No. 2 nuclear island plant) closest to the blasting position, and the specific position is the northwest corner of the No. 1 nuclear island plant (or the northwest corner of the No. 2 nuclear island plant).

(3) And 1 monitoring point (which simultaneously monitors vibration acceleration in horizontal radial direction, horizontal tangential direction and vertical direction) is arranged in a free field outside the edge of the 1MX plant (or the 2MX plant) closest to the blasting position, and the specific position is the northwest corner of the 1MX plant (or the northwest corner of the 2MX plant).

(4) And 1 monitoring point (which simultaneously monitors the vibration acceleration in the horizontal radial direction, the horizontal tangential direction and the vertical direction) is arranged in a free field outside the edge of the switching station closest to the blasting position, and the specific position is the West north corner plinth of the TC factory building.

(5) The free field outside the edge of the BOP factory building (including AC factory building, AS factory building and QT factory building and the like) nearest to the blasting position is provided with 1 monitoring point (simultaneously monitoring the vibration speed in horizontal radial direction, horizontal tangential direction and vertical direction), and the specific position is the northwest plinth of the AC factory building (or northwest corner of AS factory building or southwest corner of QT factory building).

(6) And 1 monitoring point is arranged on the GD3 closest to the blasting position (the vibration speed in the horizontal radial direction, the horizontal tangential direction and the vertical direction is monitored at the same time), and the position of the monitoring point is adjusted according to the position of the blasting center and is generally arranged on the bedrock surface of the point, closest to the pipeline between the blasting center and the GD 3.

The control threshold and the early warning value of each monitoring point are shown in Table 5

List of monitoring point locations and control thresholds

TABLE 5

The monitoring results of each monitoring point are as follows:

(1) 1, 2# LX factory building roof

1.2 # LX plant roof monitoring points: the distance between the blasting center and the monitoring point is 479-952 m. In the monitoring of the month, the vibration acceleration caused by the blasting operation does not reach the minimum trigger value of 0.005g of the monitoring instrument, and the instruments are not triggered.

(2) No. 1 nuclear island plant

No. 1 nuclear island plant monitoring point: the monitoring result is shown in Table 6, the monitoring speed value range is 6.2572-22.2889 cm/s, is 19.75-74.63% of the control threshold value, and the frequency range is 1.4 Hz-250 Hz.

GD3 speed vibration monitoring summary table 6

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(3) 1MX factory building

1MX factory building monitoring point: the distance between the blasting center and the monitoring point is 416-770 m. In the monitoring of the month, the vibration acceleration caused by the blasting operation does not reach the minimum trigger value of 0.005g of the monitoring instrument, and the instruments are not triggered

(4) TC factory building

TC plant monitoring points: the distance between the blasting center and the monitoring point is 154-963 m. In the monitoring of the month, the vibration acceleration caused by the blasting operation does not reach the minimum trigger value of 0.005g of the monitoring instrument, and the instruments are not triggered.

(5) AS factory building

AS factory building monitoring point: the distance between the blasting center and the monitoring point is 24-301 m. In the monitoring of the month, the vibration speed caused by the blasting operation does not reach the minimum trigger value of 0.02cm/s of the monitoring instrument, and the instrument is not triggered.

(6) QT factory building

QT factory building monitoring point: the monitoring result is shown in Table 7, the monitoring speed value range is 0.0274-0.758997 cm/s, is 1.97-37.99% of the control threshold value, and the frequency range is 10.7 Hz-83.3 Hz.

QT factory building monitoring summary table

TABLE 7

(7) GD3 speed

GD3 speed monitoring points: the monitoring result is shown in Table 8, the monitoring speed value range is 0.704-0.9648 cm/s, is 3.52-48.24% of the control threshold value, and the frequency range is 15.6 Hz-71.4 Hz.

GD3 speed vibration monitoring summary table

TABLE 8

(8) FCD (flash cast concrete) newly-poured concrete

FCD newly-poured concrete monitoring point: the monitoring result is shown in Table 9, the monitoring speed value range is 0.0585-0.486 cm/s, is 2.93-24.3% of the control threshold value, and the frequency range is 23.8 Hz-62.5 Hz.

FCD new concrete vibration monitoring summary table

TABLE 9

(10) FCD New concrete Top

FCD newly-poured concrete top monitoring point: the monitoring result is shown in Table 10, the monitoring speed value range is 0.0304-0.2307 cm/s, is 1.52% -11.54% of the control threshold value, and the frequency range is 14.7 Hz-41.7 Hz.

Top vibration monitoring summary table for new-cast concrete

Watch 10

By combining the embodiments, the maximum single-stage explosive quantity is strictly controlled by adopting a differential blasting technology and a hole extension blasting technology (adopting a millisecond delay network design), and the intensity of blasting vibration is controlled from the source, so that the blasting vibration is controlled within an allowable range, and the safe operation of a machine set which is put into use is ensured.

The method adopts the micro-difference deep hole blasting technology, reasonable delay time interval is not less than 50ms initially, the earthquake waves of blasting are weakened by mutually overlapping the earthquake effects generated by blasting of all holes, and the single-sound explosive quantity is controlled to reduce the blasting vibration speed and the blasting vibration acceleration.

The method adopts a small-resistance line width hole distance blasting technology (the density coefficient of blast holes is not less than 1.5 in the prior design), selects a reasonable blasting minimum resistance line and a reasonable row distance on a blasting construction site, processes the root bank in time, reduces the chassis resistance line, controls the reasonable over depth of the blast holes, and enables the explosive explosion energy to be fully released, thereby reducing the energy of converting the explosive explosion energy into the blasting seismic waves.

The method comprises the steps of performing pre-splitting blasting between a blasting place and a protected object of a machine set which is put into use, and forming a pre-splitting gap and a pre-splitting surface. After presplitting blasting, stone blasting can be carried out, and blasting seismic waves generated by the stone blasting can be reflected when the blasting seismic waves are transmitted to the presplitting surface, so that the propagation of the blasting seismic waves is weakened, and the blasting seismic waves are attenuated quickly. Thereby ensuring the safe operation of the machine set put into use.

The above is not relevant and is applicable to the prior art.

While certain specific embodiments of the present invention have been described in detail by way of illustration, it will be understood by those skilled in the art that the foregoing is illustrative only and is not limiting of the scope of the invention, as various modifications or additions may be made to the specific embodiments described and substituted in a similar manner by those skilled in the art without departing from the scope of the invention as defined in the appending claims. It should be understood by those skilled in the art that any modifications, equivalents, improvements and the like made to the above embodiments in accordance with the technical spirit of the present invention are included in the scope of the present invention.

Claims

1. A blasting method for a negative excavation blasting structure of a nuclear island corridor foundation pit is characterized in that a blasting area of the corridor foundation pit is formed by enclosing an inner ring line and an outer ring line;

the blasting area of the ring corridor foundation pit is divided into a plurality of blasting areas, and the plurality of blasting areas are sequentially divided into two bilaterally symmetrical first blasting areas, two bilaterally symmetrical second blasting areas, two bilaterally symmetrical third blasting areas and two bilaterally symmetrical fourth blasting areas along the direction close to the protection area;

the first pre-splitting hole, the second pre-splitting hole, the first cut hole, the second cut hole and the first main blasting hole are all provided with a charging section and a filling section;

the blasting method comprises the following steps:

s1, detonating a first pre-crack hole to form an inner ring groove;

and S4, detonating the second pre-cracked hole to form an outer ring groove.

2. A blasting method according to claim 1, wherein the gallery foundation pit is planned to have a first thickness layer and a second thickness layer in the depth direction, the first pre-split hole, the second pre-split hole, the first cut hole, the second cut hole and the first main blast hole are all arranged in the first thickness layer, the depth of the gallery foundation pit is H, the first thickness layer is H, and H is greater than 1/2H.

3. A blasting method according to claim 2, wherein after step S3 is completed, a main blasting region and a blasting region are arranged in the second thickness layer, a plurality of second main blasting holes are arranged at intervals in the main blasting region, the blasting region is arranged around the main blasting region, a plurality of third slotted holes are arranged in the blasting region, the third slotted holes and the second main blasting holes are filled with powder and then detonated, and then step S4 is carried out, wherein the second main blasting holes are filled with radially uncoupled powder.

4. A method of blasting according to claim 3, wherein the initiation network of the primary blast zone is configured to provide delayed initiation between the perforations.

5. A method of blasting according to claim 1, wherein in step S2, auxiliary holes are provided in the blasting region of the excavation pit near both the inner and outer annular lines.

6. A method of blasting according to claim 1, wherein in steps S2 and S3, shallow hole blasting is used, the blast hole density factor is less than 1.5, the charging structure of the first, first and second cut holes is continuous charging, the blast hole pitch is less than the hole pitch, the hole pitch is less than the hole depth, and the length of the plugged portion is greater than 1/2 of the depth of the blast hole; the first cut holes are arranged into inclined hole double wedges, and the inclination angle of blast holes is 50-90 degrees.

7. A method of blasting according to any one of claims 1 to 6, wherein in step S3, the plurality of blasting intervals are initiated in the following order: a first blasting interval, a second blasting interval, a third blasting interval and a fourth blasting interval, wherein the detonation interval time is 75-150ms; and initiating at intervals in each blasting interval.

8. A method of blasting according to claim 1, wherein in step S1, the first pre-split holes have a pitch of 0.6 to 1.1m and a row pitch of 2m; the first pre-splitting hole adopts a spaced charging mode and comprises a reinforced charging section, a normal charging section and a weakened charging section.

9. A method of blasting according to claim 1, wherein in step S4, the outer ring grooves are formed by bidirectional energy focusing blasting to form smooth blasting.