CN114018112A

CN114018112A - Nuclear island and corridor foundation pit negative excavation blasting structure and blasting method

Info

Publication number: CN114018112A
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: 2022-02-08
Anticipated expiration: 2041-10-20
Also published as: CN114018112B

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 every 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 corridor 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; a flexible material is filled at the bottom of the hole to be used as a cushion layer; 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; the initiation forms cracks along the inner and outer circumferences of the ring corridor. 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 the first pre-cracked hole to form an inner ring groove;

s2, detonating the first cut hole, and forming a 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 are detonated, and the first main detonating holes of each blasting section extend from a position far away from the protection area to a position close to the protection area for detonation;

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

Further, will the gallery foundation ditch is prescribed a thickness layer and a second thickness layer along the direction of depth, first presplitting hole, second presplitting hole, first undermined hole, second undermined 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 arranged in the main explosion area at intervals, the explosion area is arranged around the main explosion area, a plurality of third undercut holes are arranged in the explosion area, the third undercut holes and the second main explosion holes are detonated after charging, and then the step S4 is performed, wherein the second main explosion holes adopt radial uncoupled charging.

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

Further, in step S2, auxiliary holes are provided at the edge of the blasting area of the gallery foundation pit near the inner and outer ring lines.

Further, in steps S2 and S3, a shallow hole blasting mode is adopted, the blast hole density coefficient 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 pitch is less than the hole pitch, the hole pitch is less than the hole depth, and the length of the blocking section is greater than 1/2 of the blast hole depth; 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 75-150 ms; and initiating at intervals in each blasting interval.

Further, in step S1, the pitch of the first pre-split holes is 0.6 to 1.1m, and the row pitch is 2 m; 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 50 cm.

Further, in step S4, the outer ring groove is formed by a smooth blasting using a bidirectional energy-gathering 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 initiation 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-sound 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 is not less than 1.5) is adopted, the reasonable blasting minimum resistance line and row distance are selected at the blasting construction site, so that the adjacent blasting funnels cannot be connected into a whole, the blank surface after blasting is correspondingly increased, the explosive energy is more uniformly distributed in the medium in the blasting funnels, the blasting square amount is increased, the blasting pile is more concentrated, and because the minimum resistance line is smaller, the reflection effect of the stress wave of the free surface is enhanced, when the explosion stress wave is transmitted to the free surface, the reflection tensile stress is generated to lead the surface layer medium to be broken and move, 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 delayed, the energy utilization rate of broken rocks is improved, the explosive energy can be fully released, and the energy of the explosive energy converted into blasting seismic waves is reduced.

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 is 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. A blasting area of the annular gallery 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 sections, and the plurality of blasting sections are sequentially divided into two first blasting sections 101, two second blasting sections 102, two third blasting sections 103 and two fourth blasting sections 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.

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

s2, detonating the first cut hole 4 to form a 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 interval to form grooves, wherein when the first blasting interval 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 interval 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-split hole 301 to form an outer ring groove.

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 step S3 is completed, a main explosion area and an explosion area are provided in the second thickness layer 9, a plurality of second main explosion holes 10 are provided at intervals in the main explosion area, the explosion area is surrounded around the main explosion area, a plurality of third cut holes (not shown in the figure) are provided in the explosion area, the third cut holes and the second main explosion holes 10 are charged and then detonated, and then step S4 is performed, and the second main explosion holes 10 are charged with radially uncoupled charges.

The initiation network of the primary detonation zone is configured to delay initiation between the holes.

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

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 greater 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 75-150 ms; 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, the current design slope of the side slope is relatively slow, and when the hole diameter is relatively small, the hole drilling position is easy to shift, the hole diameter of the first pre-splitting hole 201 in the project can be determined to be 89mm, the hole pitch of the first pre-splitting hole 201 is 0.6-1.1m, and the row pitch is 2 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 50 cm.

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 step S1:

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

Pitch of first pre-split holes 201: in order to weaken the influence of blasting on the side slope, the hole pitch of the pre-splitting holes must be reasonably determined, the diameter of the pre-splitting holes is generally 8-15 times, the hole pitch of the pre-splitting holes is 0.6-1.1m, medium weathering and micro weathering are 1.0m, and strong weathering in a pre-splitting blasting area can be 0.9 m.

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 is taken, and the adjustment is performed 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 structural sideline is arranged outside the bottom opening of the side slope within 1.5m, and the construction channel is arranged within 1.5m, so the excavation of the bottom plate cannot be influenced when the pre-splitting depth of the side slope is beyond 30cm to the bottom plate.

Thread loading density: in this embodiment, the density of the powder in the wire is 0.286-0.33 kg/m.

As shown in fig. 4, the first pre-split hole 201 charge structure: in this engineering, the powder charge of first prefracture hole 201 bottom adopts and strengthens the medicine section, strengthens the medicine section and is 1m, and first prefracture hole 201 middle part adopts normal medicine section, and normal medicine section adopts the interval powder charge, and the cartridge interval is 40 ~ 50 cm. The distance between the weakening section and the medicine rolls is 50 cm. 1/2 taking a single medicine bag as a normal section, the upper part of the pre-splitting hole is about 1.4mThe packing section is not charged with explosive. 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 string and the bamboo chips are filled into the pre-cracked holes and are filled. The reinforcing medicine section is

The emulsion explosive of (1).

Steps 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 89 mm.

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 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 loading is 1.4-2.6 kg.

According to the blasting excavation experience, the unit consumption of explosive is 0.45kg/m³. The blasting parameters can be determined according to the following table.

Shallow hole blasting parameter table (Table 2)

The arrangement of the blast holes in the shallow holes ensures 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 basis that the hole pitch is smaller than the depth of the blast holes.

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 plug length 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 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 second thickness layer 9A 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 the integrity of the bedrock and reduce the damage of the blasting action to the bedrock. Minimum line of resistance 1.0 m; the row spacing is 1.0m, the hole spacing is 1.0m, the blast hole depth is 1.5m, the explosive is arranged according to quincuncial holes, the diameter of each blast hole is 76mm, the packing length is ensured to be more than 1.0m, the diameter of each explosive roll is 32mm, every two explosives are arranged in parallel, the single-hole explosive loading is within 0.7kg, the blast holes are not ultra-deep, and the unit consumption is 0.45kg/m³. And during actual construction, determining according to the test blasting experiment parameter result.

The second thickness layer 9 undercut blasting parameter table (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 the reasonable delay time interval and the detonation sequence.

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

wherein: k is a coefficient related to rock properties, structural structure and blasting conditions, and 15-25 is taken under open blasting conditions

W-line of least resistance, m.

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

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 detonator segment is installed in the hole, for example, the MS-10 segment in the hole, and the MS-2/3/5 segment is used outside the hole for delay, so as to form the single-hole single-ring network.

In other embodiments, as shown in FIG. 8, if the hole is filled with sectionally spaced charges, two sectionally detonators MS-11/10 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 middle packing length is more than 1.0m, so as to form a sectionalized network in the hole.

In step S4, a smooth surface blasting is formed by bidirectional energy-gathering 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 point (simultaneously monitoring vibration acceleration in horizontal radial direction, horizontal tangential direction and vertical direction) is arranged on the 1 and 2# LX factory building roofs nearest to the blasting position, and the specific positions are the positions of the west center lines of the 1 and 2# LX factory building roofs.

(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 arranging 1 monitoring point (simultaneously monitoring vibration acceleration in horizontal radial direction, horizontal tangential direction and vertical direction) in a free field outside the edge of the 1MX factory building (or the 2MX factory building) closest to the blasting position, wherein the specific position is the northwest angle of the 1MX factory building (or the northwest angle of the 2MX factory building).

(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) The GD3 nearest to the blasting position is provided with 1 monitoring point (simultaneously monitoring the vibration speed in the horizontal radial direction, the horizontal tangential direction and the vertical direction), 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 where the blasting center is closest to the GD3 pipeline.

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 plant 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

(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 point: 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-section 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 put into use is ensured.

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 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;

2. The blasting method for the negative excavation blasting structure of the nuclear island corridor foundation pit as claimed in claim 1, characterized by comprising the following steps:

s1, detonating the first pre-cracked hole to form an inner ring groove;

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

3. A blasting method according to claim 2, 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.

4. A method of blasting according to claim 3, wherein after step S3, a main blast zone and a detonation zone are provided in the second thickness layer, wherein a plurality of second main blast holes are provided at intervals in the main blast zone, the detonation zone surrounds the main blast zone, and a plurality of third slotted holes are provided in the detonation zone, and wherein the third slotted holes and the second main blast holes are detonated after being charged with the powder, and then step S4 is performed, wherein the second main blast holes are radially uncoupled from the powder.

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

6. A method of blasting according to claim 2, wherein in step S2, the blast area of the excavation pit of the annular gallery has auxiliary holes near the edges of the inner and outer annular lines.

7. A method of blasting according to claim 2, wherein in steps S2 and S3, shallow hole blasting is used, the hole packing factor of each hole is less than 1.5, the charge configuration of the first, first and second cutholes is continuous, the 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 the depth of the hole; the first cut holes are arranged into inclined hole double wedges, and the inclination angle of blast holes is 50-90 degrees.

8. A method of blasting according to any one of claims 2 to 6, wherein in step S3, the plurality of blasting intervals are initiated in the following sequence: a first blasting interval, a second blasting interval, a third blasting interval and a fourth blasting interval, wherein the detonation interval time is 75-150 ms; and initiating at intervals in each blasting interval.

9. A method of blasting according to claim 2, wherein in step S1, the first pre-split holes have a pitch of 0.6 to 1.1m and a row pitch of 2 m; 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.

10. A method of blasting according to claim 2, wherein the outer ring groove is formed in step S4 by bidirectional energy focusing blasting to form a smooth blasting.