Combined blasting control method for directional reinforced throwing blasting and protective layer excavation

Abstract

The invention provides a directional reinforced throwing blasting and protective layer excavation combined blasting control method, which comprises the following steps of: 1, planning to-be-excavated rock masses controlled by different targets in a zoning manner, designing deep hole bench blasting parameters in a zoning manner, and dividing a side slope excavation region into a main blasting region and a protective layer excavation region, the whole to-be-detonated area is detonated in a segmented and delayed mode through digital detonators; 2, directional reinforced throwing blasting is adopted in the main blasting area, and reinforced throwing holes are formed in the main blasting area; 3, the protective layer excavation area is subjected to buffer presplit zone excavation blasting, a buffer hole and a presplit hole are formed behind the common throwing hole, a buffer presplit zone is formed, excavation of the protective layer is completed, and damage to the reserved slope rock mass is reduced; and 4, combined blasting is conducted in combination with the partition blasting division. Based on the blasting method, the effective blasting slag throwing rate can be remarkably increased, the comprehensive slag turning workload is reduced, and the cost is saved.

Description

Technical Field

[0001] The invention belongs to the technical field of controlled blasting in a rock slope excavation process, and in particular relates to a combined blasting control method of directional reinforced throwing blasting and protective layer excavation of a high arch dam. Background Art

[0002] With the gradual completion of the development of downstream gradient water conservancy hubs, more hydropower resources are being used in high-altitude and cold mountain valley areas. The excavation work surface of dam slopes in such areas is narrow and steep, and the slopes are severely weathered and unloaded. The annual effective excavation construction period is less than 6 months. Taking the excavation of arch dams above 200m as an example, the amount of earth and stone excavation and slag discharge can reach 8 million m 3 The maximum monthly excavation intensity during the peak period can reach 600,000 m 3 , the slag transportation intensity is extremely high in a short period of time.

[0003] Due to the long construction period, many processes, steep slope terrain, difficult cable platform road construction and dump truck transportation arrangements, a large amount of loose stone slag from cable platform excavation is often accumulated during slope excavation. According to the slag excavation measures taken by traditional open excavation, the slag blocks cannot be directly discharged after loose blasting of each excavation surface in the step section. It is necessary to use a backhoe to turn the slag from the outside to the inside and from top to bottom to the slag collection platform, which consumes a lot of manpower, equipment and slag discharge costs. As the height increases, the number of slag turning also increases and can even reach dozens of times. Therefore, when using deep hole step blasting to strip the slope rock mass, how to improve the effective throwing rate, timely clean up the blasting piles generated by loose blasting, reduce the interference of slag removal operations, and ensure that the pre-cracked wall surface is disturbed as little as possible has become a key construction goal. Summary of the invention

[0004] In order to reduce the number of slag turning and transportation and solve the problem of excavation slag transportation for slag turning excavation with large excavation thickness and site road restrictions, the present invention intends to improve the process from the perspective of blasting excavation design, and proposes a combined blasting technology of deep hole step directional enhanced throwing and protective layer buffer pre-cracking zone excavation, which can significantly improve the effective throwing rate of slag, reduce the comprehensive slag turning operation volume, and save costs.

[0005] The technical solution adopted by the present invention to solve the problems existing in the prior art is as follows:

[0006] A combined blasting control method of directional enhanced throwing blasting and protective layer excavation specifically comprises the following steps:

[0007] Step 1: Plan the rock mass to be excavated under different target control zones, design deep hole step blasting parameters according to the on-site drilling equipment and backhoe bucket capacity, divide the slope excavation into the main blasting zone and the protective layer excavation zone, use different blasting parameters and charging forms in the two operation zones, and use digital detonators for segmented delayed detonation in the entire blasting zone;

[0008] Step 2: The main gun area in step 1 is the throwing blasting operation area. Directional enhanced throwing blasting is adopted in this area to throw the rock mass in the outer blasting area to the designated position as much as possible, so as to achieve the purpose of convenient and rapid collection and transportation. Reinforced throwing holes are provided in the main gun area. When the number of rows of reinforced throwing holes in the main gun area is more than 3 rows, energy-boosting throwing holes are provided after the reinforced throwing holes.

[0009] Step 3: Excavation blasting is performed in a buffer pre-splitting zone for the protective layer excavation area in step 1. One to two rows of buffer holes are arranged after the common casting holes, followed by two rows of pre-splitting holes to form a buffer pre-splitting zone, so as to complete the excavation of the protective layer and reduce the damage to the retained slope rock mass.

[0010] Step 4: Combine the above partition blasting divisions and carry out combined blasting.

[0011] In step 1, the deep hole step blasting parameters first determine the step height, blast hole diameter and charge roll diameter, usually 3-4m 3 When bucketing, the step height is 12-15m, 1m 3 When bucketing, the step height is 10-12m. In strong and medium weathered rocks, blastholes with a diameter of more than 100mm are used, and in medium hard and hard rocks, blastholes with a diameter of 70-90mm are used. The corresponding main blasting hole charge diameter is 10-20mm smaller than the blasthole diameter.

[0012] In the step 1, the blasting area within 10m in front of the rock mass in the slope excavation area is reserved as the protective layer excavation area, and the front blasting area of ​​the protective layer excavation area is the main blasting area.

[0013] In step 1, the step height of each of the two working areas is 15m, the width is 10m, and the blasthole diameter is 100mm.

[0014] When the on-site drilling equipment in step 1 is equipped with a bulldozer and a backhoe, the bulldozer power is not less than 160kw, and the backhoe bucket capacity is not less than 1.8m 3 The pre-splitting drilling, main blasting drilling and slag turning require sufficient mechanical equipment and quality inspection personnel. If the drilling accuracy does not meet the requirements, the throwing effect will be unsatisfactory, which will in turn affect the workload of slag turning. In addition, difficulties in pre-splitting will cause over-excavation and under-excavation of the slope and secondary treatment.

[0015] In the step 2, the drilling inclination angle of the throwing blasting operation area is aimed at the problem that the resistance line of the bottom plate of the vertical blasthole is too large. An inclined blasthole is drilled at an elevation angle to the horizontal plane, so that most of the medium in the blasting funnel is close to the direction of the minimum resistance line, which can reduce the rock resistance at the bottom of the step and throw it obliquely upward. The inclination angle of the throwing hole is controlled at 50° to 60°.

[0016] The blasting parameters of the throwing blasting operation area in the step 2 are: the throwing distance decreases as the ratio of the blast hole spacing a to the blast hole row spacing b decreases. In order to increase the blasting volume and throwing volume, the row spacing should satisfy a=(1.2~1.5)b. Generally, the hole mouth is blocked at 1.5m, and the minimum resistance line W is 2.5m. In order to enhance the forward pushing ability of the rear row of blast holes and reduce the clamping effect, the unit consumption from the front row of blast holes to the rear row of blast holes is gradually increased, which is specifically reflected in reducing the row spacing of the rear row of holes or appropriately increasing the single hole charge of the rear row of holes.

[0017] The segmented design of the throwing hole in the throwing blasting operation area in step 2 is: an ordinary section and a bottom reinforcement section. The length of the bottom reinforcement section is set to 1 / 3 of the length of the blasthole. The ordinary section uses a 70mm diameter charge, and the reinforced section uses a 90mm diameter charge. The middle interval is blocked with a 1m encapsulated sandbag. The ordinary section is blasted 0.5s before the reinforced section. After the bottom reinforcement section is detonated, the secondary crushing of the previously thrown rock mass is completed, the volume of large rocks is reduced, and the slag throwing distance is further enhanced.

[0018] The charging structure of the throwing blasting operation area in the step 2 is as follows: the blasting hole is usually equipped with an emulsion explosive with a diameter of 70 mm and is continuously charged by air coupling (i.e., air is filled between the charge roll and the borehole wall). In order to enhance the throwing effect, the incompressible property of water and the water wedge effect under high temperature and pressure conditions are utilized, and the charging of the boreholes in the throwing blasting area is continuously charged by water coupling (i.e., a plastic film bag is filled between the charge roll and the borehole wall and water is injected and sealed) to increase the quasi-static pressure of the blasting, extend the action time, and enhance the throwing effect. The boreholes in the throwing blasting area include enhanced throwing holes and energy-replenishing throwing holes. The charge of the energy-replenishing throwing holes is slightly higher than that of the enhanced throwing holes by 10% to overcome the clamping effect increased by too many detonation rows.

[0019] For the common throwing holes in the protective layer excavation area in step 3, a 70 mm diameter cartridge is used for air-coupled continuous charging, and the drilling inclination is consistent with the front row throwing blasting area. At the same time, the single-hole single-bang detonation method is avoided, the throwing effect of simultaneous detonation is increased, the delay time between adjacent rows and the possibility of slag blasting are reduced, and the post-cracking effect is reduced.

[0020] The buffer holes in the protective layer excavation area in step 3 are designed to have a unit consumption roughly similar to that of the front row blasting holes, but with smaller hole network parameters and single-hole charge, by reducing the hole diameter, hole spacing and rear row spacing, and using uncoupled interval charging of similar pre-splitting holes. At the same time, the bottom of the hole is backfilled with 0.5m of loose slag to reduce the destructive effect on the rear row slope.

[0021] The pre-splitting zone in the excavation area of ​​the protective layer in the step 3 is designed as follows: double-row pre-splitting blasting holes are designed, and the charge is tied with bamboo strips with a diameter of 32 mm. The two rows of pre-splitting holes are spaced 0.8 m apart. The rear row of pre-splitting holes close to the slope are designed according to the traditional pre-splitting blasting design experience, and the distance between the holes is 0.6 m; the distance between the front row of pre-splitting holes is 0.8 m. In order to generate a pre-splitting crushing zone before the casting holes are detonated, the front row of pre-splitting holes are detonated 100 ms earlier than the rear row of pre-splitting holes, guiding the rear row of pre-splitting blasting energy to deflect toward the front row of pre-cracks. At the same time, the rear row of pre-splitting holes with denser hole spacing can still form a good seam, and the formation of the pre-splitting zone further plays a role in buffering and vibration reduction.

[0022] In step 2, mud filling is used to protect the wall in the throwing blasting operation area: when the throwing blasting encounters developed joints and fissures and loose and broken rock formations, not only is it difficult to drill holes with larger inclination angles, but the through-developed cracks are also prone to detonation gas leakage, seriously affecting the throwing effect. On the basis of water medium filling, it is improved to yellow mud slurry filling to seal the cracks in the hole wall and prevent gas leakage.

[0023] In view of the problem that the blast hole is relatively inclined, in order to facilitate the delivery of the explosive roll into the hole, a special charging blasting stick with a plug that can be spliced ​​for deep hole blasting is made. The blasting stick is made of hard plastic and is divided into 2m sections. When used with a straight-through joint, the deep hole blasting stick can be flexibly disassembled and assembled.

[0024] The present invention adopts high-precision digital electronic detonators. When detonating in sections in the main throwing blasting hole, the upper ordinary throwing section detonating detonator is accurately controlled to be detonated 0.5s earlier than the lower reinforced throwing section. When double-layer buffer pre-splitting blasting is adopted in the protective layer excavation area, the digital detonators are networked and detonated in the order of front pre-splitting holes → rear pre-splitting holes → throwing blasting holes → buffer holes to prevent the occurrence of a large number of ground detonating detonators and ensure the network delay accuracy.

[0025] The present invention has the following advantages:

[0026] (1) It has a multi-objective parallel optimization function. For simple loosening blasting, it can make full use of large-diameter, deep-hole high-step and other process equipment to discharge the stripped rock mass to the designated location. For simple pre-splitting blasting, it can better control the damage range of the retained slope rock mass and the slope pull-back effect;

[0027] (2) The refined zoning design has the characteristics of low cost, high efficiency and little damage to the foundation surface. Compared with the traditional step blasting, it is a more advanced blasting method for handling the reserved rock mass and post-blasting slag in the rapid blasting excavation of high slopes;

[0028] (3) Directional enhanced throwing treatment;

[0029] (4) Triple insurance for excavation of protective layer: the last row of traditional pre-crack holes; the second layer of pre-crack holes and the pre-crack fracture zone formed; buffer holes in the buffer zone;

[0030] (5) Directional enhanced throwing blasting is used to throw the blasted rocks directly onto the riverbed, reducing the auxiliary time between blasting, slag removal and support operations;

[0031] (6) Based on the design of buffer holes and pre-cracking zones, the large-scale directional throwing and protective layer excavation methods can fully utilize the advantages of high and steep slopes and deep river valley terrain, increase the throwing speed of flying rocks in front blasting, increase the probability of secondary collision and crushing of rock mass in the air, reduce the clamping effect of rear-row blasting holes, and improve the overall rock breaking and throwing effect, thereby greatly improving the efficiency of blasting and shoveling and retaining the range of rock damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a flow chart of the method of the present invention;

[0033] Figure 2 This is a schematic diagram of the combined blasting of enhanced throwing and pre-splitting zone according to the method of the present invention;

[0034] Figure 3 It is a cross-sectional view of a blasthole according to the method of the present invention;

[0035] Figure 4 It is a blasthole plane and network schematic diagram of the method of the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0037] like Figure 1-4 As shown, a combined blasting control method of directional enhanced throwing blasting and protective layer excavation includes the following steps:

[0038] Step 1: Plan the rock mass to be excavated under different target control zones, design deep hole step blasting parameters according to the on-site drilling equipment and backhoe bucket capacity, divide the slope excavation into the main blasting zone and the protective layer excavation zone, use different blasting parameters and charging forms in the two operation zones, and use digital detonators for segmented delayed detonation in the entire blasting zone;

[0039] The deep hole step blasting parameters first determine the step height, blast hole diameter and charge diameter, usually 3-4m 3 When bucketing, the step height is 12-15m, 1m 3When the bucket is used, the step height is 10-12m. In strong and medium weathered rocks, blastholes with a diameter of more than 100mm are used, and in medium hard and hard rocks, blastholes with a diameter of 70-90mm are used. The corresponding main blast hole charge diameter is 10-20mm smaller than the blasthole diameter; the blasting area within 10m in front of the rock mass in the slope excavation area is the protective layer excavation area, and the front blasting area of ​​the protective layer excavation area is the main blasting area. The step height of each of the two working areas is 15m, the width is 10m, and the blasthole diameter is 100mm; when the on-site drilling equipment is equipped with a bulldozer and a backhoe, the bulldozer power is not less than 160kw, and the backhoe bucket capacity is not less than 1.8m 3 The pre-splitting drilling, main blasting drilling and slag turning require sufficient mechanical equipment and quality inspection personnel. If the drilling accuracy does not meet the requirements, the throwing effect will be unsatisfactory, which will in turn affect the workload of slag turning. In addition, difficulties in pre-splitting will cause over-excavation and under-excavation of the slope and secondary treatment.

[0040] Step 2, the main gun area in step 1 is the throwing blasting operation area, and directional enhanced throwing blasting is adopted in this area to throw the rock mass in the outer blasting area to the designated position as much as possible, so as to achieve the purpose of convenient and rapid collection and transportation. The main gun area is provided with enhanced throwing holes. When the number of rows of enhanced throwing holes in the main gun area is more than 3 rows, energy-replenishing throwing holes are set after the enhanced throwing holes; the drilling inclination angle of the throwing blasting operation area is aimed at the problem that the vertical blast hole chassis resistance line is too large, and an inclined blast hole with an elevation angle to the horizontal plane is drilled, so that most of the medium in the blasting funnel is close to the direction of the minimum resistance line, which can reduce the rock resistance at the bottom of the step and throw it obliquely upward, and the inclination angle of the throwing hole is controlled at 50° to 60°;

[0041] The blasting parameters of the throwing blasting operation area are as follows: the throwing distance decreases with the decrease of the ratio of the blasthole spacing a to the blasthole row spacing b. In order to increase the blasting volume and throwing volume, the row spacing should satisfy a=(1.2~1.5)b. Generally, the hole mouth is blocked at 1.5m, and the minimum resistance line W is 2.5m. In order to enhance the forward pushing ability of the rear row blastholes and reduce the clamping effect, the unit consumption from the front row blastholes to the rear row blastholes is gradually increased, which is specifically reflected in reducing the row spacing of the rear row holes or appropriately increasing the charge of the single hole of the rear row holes.

[0042] The blasting hole in the blasting operation area is designed in sections: a common section and a bottom reinforced section. The length of the bottom reinforced section is set to 1 / 3 of the length of the blasting hole. The common section uses a 70mm diameter cartridge, and the reinforced section uses a 90mm diameter cartridge. The middle interval is blocked with a 1m sealed sandbag. The common section is blasted 0.5s before the reinforced section. After the bottom reinforced section is detonated, the secondary crushing of the previously thrown rock mass is completed, reducing the volume of large rocks and further enhancing the slag throwing distance.

[0043] Charging structure of the throwing blasting operation area: Usually the blasting holes are equipped with emulsion explosives with a diameter of 70mm and are continuously charged by air coupling (i.e., air is filled between the charge roll and the borehole wall). In order to enhance the throwing effect, the incompressible characteristics of water and the water wedge effect under high temperature and pressure conditions are utilized. The blasting holes in the throwing blasting area are continuously charged by water coupling (i.e., a plastic film bag is filled between the charge roll and the borehole wall and water is injected and sealed) to increase the quasi-static pressure of the blasting, extend the action time, and enhance the throwing effect. The blasting holes in the throwing blasting area include enhanced throwing holes and energy-replenishing throwing holes. The charge of the energy-replenishing throwing holes is slightly higher than that of the enhanced throwing holes by 10% to overcome the clamping effect increased by too many detonation rows.

[0044] Mud filling is used to protect the wall in the throwing blasting operation area: When strengthening throwing blasting and encountering developed joints and fissures and loose and broken rock formations, not only is it difficult to drill holes with large inclination angles, but the through-developed cracks are also prone to leakage of detonation gases, seriously affecting the throwing effect. On the basis of water medium filling, it is improved to yellow mud slurry filling to seal the cracks in the hole wall and prevent gas leakage.

[0045] Step 3: Excavation blasting is performed in a buffer pre-splitting zone for the protective layer excavation area in step 1. One to two rows of buffer holes are arranged after the common casting holes, followed by two rows of pre-splitting holes to form a buffer pre-splitting zone, so as to complete the excavation of the protective layer and reduce the damage to the retained slope rock mass.

[0046] Ordinary throwing holes in the protective layer excavation area: use 70mm diameter charge rolls with air-coupled continuous charging, the drilling inclination is consistent with the front row throwing blasting area, and avoid the single-hole single-bang detonation method, increase the throwing effect of simultaneous detonation, reduce the delay time between adjacent rows and the possibility of slag blasting, and reduce the post-cracking effect;

[0047] Buffer holes in the excavation area of ​​the protective layer: by reducing the hole diameter, hole spacing and rear row spacing, and using uncoupled interval charging of similar pre-splitting holes, the design unit consumption is roughly similar to that of the front row blasting holes, but it is a blasting with smaller hole network parameters and single hole charge. At the same time, 0.5m loose slag is backfilled at the bottom of the hole to reduce the damage to the rear row slope surface; Pre-splitting zone in the excavation area of ​​the protective layer: double-row pre-splitting blasting holes are designed, with 32mm diameter bamboo strips tied for charging, and the two rows of pre-splitting holes are 0.8m wide. The rear row pre-splitting holes close to the slope are designed according to the traditional pre-splitting blasting design experience, with a hole spacing of 0.6m; the front row pre-splitting holes are 0.8m apart. In order to generate a pre-splitting crushing zone before the throwing hole is detonated, the front row pre-splitting holes are detonated 100ms earlier than the rear row pre-splitting holes, guiding the rear row pre-splitting blasting energy to deflect toward the front row pre-cracks. At the same time, the rear row pre-splitting holes with dense hole spacing can still form cracks well. The formation of the pre-splitting zone further plays a role in buffering and vibration reduction.

[0048] Step 4: Combine the above partition blasting divisions and carry out combined blasting.

[0049] In order to solve the problem of inclined blastholes and facilitate the delivery of explosive rolls into the holes, special charging blasting sticks with plugs for deep hole blasting are made. The blasting sticks are made of hard plastic and divided into 2m sections. When used with straight-through joints, the deep hole blasting sticks can be flexibly disassembled and assembled.

[0050] The present invention adopts high-precision digital electronic detonators. When detonating in sections in the main throwing blasting hole, the upper ordinary throwing section detonating detonator is accurately controlled to be detonated 0.5s earlier than the lower reinforced throwing section. When double-layer buffer pre-splitting blasting is adopted in the protective layer excavation area, the digital detonators are networked and detonated in the order of front pre-splitting holes → rear pre-splitting holes → throwing blasting holes → buffer holes to prevent the occurrence of a large number of ground detonating detonators and ensure the network delay accuracy.

[0051] Embodiment 1:

[0052] For the rock mass to be excavated based on different target control, the blasting of the rock mass to be excavated can be divided into loosening blasting and throwing blasting according to different purposes. The blasting action index n is used as a parameter to quantify the loosening and throwing blasting effects. When the blasting action index n (that is, the radius of the blasting funnel r / the closest distance from the center of the explosive bag to the open surface is the minimum resistance line W) is less than 1, it is loosening blasting. The larger the n value, the better the effect of throwing blasting. The unit consumption of explosives means that every blasting 1m 3 The amount of explosives consumed by the rock is a conceptual indicator for measuring the blasting effect. According to the existing technology, taking the traditional blasting design with a step height of 15m as an example, the hole spacing is 3m, the row spacing is 2.5m, the hole mouth is blocked at 1.5m, and the minimum resistance line is 3m. The blasthole is filled with a 70mm diameter cartridge and air-coupled. Based on the 70mm cartridge with a charge of 4.2kg / m per linear meter, the charge of the blasting blasthole is (15-1.5)*4.2=56.7kg, and the unit consumption q=Q / abH=0.5. Based on the empirical formula of the blasting charge during throw blasting, Q=(0.4+0.6n 2 )eqW 3 , the calculated blasting index n = 2.51. When the reinforced throwing blasting design of the present invention is adopted, the reinforced throwing hole bottom reinforcement section adopts 90mm diameter charge roll, and the charge per linear meter is 7kg / m. At this time, the charge of the reinforced throwing blasting blast hole is 5*7+(10-1.5)*4.2=70.7kg, the hole spacing of the blast hole is 3m, the row spacing is 2.5m, the minimum resistance line is 2.5m, the unit consumption q=Q / abH=0.628, and the calculated blasting index n=3.37. Comparison shows that the blasting index is improved by 25.5%.

[0053] Similarly, when excavating with the prior art, only one layer of pre-splitting blasting is designed and the spacing between pre-splitting holes is usually greater than 0.8m. The pre-crack effect produced is obviously not as good as the pre-splitting fracture zone formed by two layers of pre-splitting holes. In addition, the penetration effect of the pre-splitting holes after blasting is not as good as the pre-splitting holes with a hole spacing of 0.6m in this scheme.

[0054] The protection scope of the present invention is not limited to the above-mentioned embodiments. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the scope and spirit of the present invention. If these changes and modifications fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include these changes and modifications.

Claims

1. A combined blasting control method of directional enhanced throwing blasting and protective layer excavation, characterized in that: The steps include: Step 1: Plan the rock mass to be excavated under different target control zones, design deep hole step blasting parameters according to the on-site drilling equipment and backhoe bucket capacity, divide the slope excavation into the main blasting zone and the protective layer excavation zone, use different blasting parameters and charging forms in the two operation zones, and use digital detonators for segmented delayed detonation in the entire blasting zone; Step 2: The main gun area in step 1 is the throwing blasting operation area. Directional enhanced throwing blasting is adopted in this area to throw the rock mass in the outer blasting area to the designated position as much as possible, so as to achieve the purpose of convenient and rapid collection and transportation. Reinforced throwing holes are provided in the main gun area. When the number of rows of reinforced throwing holes in the main gun area is more than 3 rows, energy-boosting throwing holes are provided after the reinforced throwing holes. Step 3: Excavation blasting is performed in a buffer pre-splitting zone for the protective layer excavation area in step 1. Several rows of buffer holes are arranged after the common casting holes, and several rows of pre-splitting holes are arranged immediately thereafter to form a buffer pre-splitting zone, so as to complete the excavation of the protective layer and reduce the damage to the retained slope rock mass; Step 4: Combine the above partition blasting divisions and carry out combined blasting.

2. A combined blasting control method of directional enhanced throwing blasting and protective layer excavation as claimed in claim 1, characterized in that: In step 1, the deep hole step blasting parameters first determine the step height, blast hole diameter and charge roll diameter, usually 3-4m 3 When bucketing, the step height is 12-15m, 1m 3 When bucketing, the step height is 10-12m, blastholes with a diameter of more than 100mm are used in strongly to moderately weathered rocks, and blastholes with a diameter of 70-90mm are used in medium to hard and hard rocks. The corresponding main blasting hole charge diameter is 10-20mm smaller than the blasthole diameter.

3. A combined blasting control method of directional enhanced throwing blasting and protective layer excavation as claimed in claim 1, characterized in that: In the step 1, the blasting area within 10m in front of the rock mass in the slope excavation area is the protective layer excavation area, and the front blasting area of ​​the protective layer excavation area is the main blasting area; the step height of each of the two working areas in the step 1 is 15m, the width is 10m, and the blasting hole diameter is 100mm; when the on-site drilling equipment in the step 1 is equipped with a bulldozer and a backhoe, the bulldozing power of the bulldozer is not less than 160kw, and the backhoe bucket capacity of the backhoe is not less than 1.8m 3 .

4. A combined blasting control method of directional enhanced throwing blasting and protective layer excavation as claimed in claim 1, characterized in that: The inclination angle of the drilling of the throwing holes in the throwing blasting operation area in the step 2 is controlled at 50° to 60°; the blasting parameters in the throwing blasting operation area in the step 2 are: the throwing distance decreases as the ratio of the blast hole spacing a to the blast hole row spacing b decreases, the row spacing satisfies a=(1.2~1.5)b, the hole mouth is blocked at 1.5m, and the minimum resistance line W is 2.5m.

5. The combined blasting control method of directional enhanced throwing blasting and protective layer excavation as claimed in claim 1, characterized in that: The segmented design of the throwing hole in the throwing blasting operation area in step 2 is: an ordinary section and a bottom reinforcement section. The length of the bottom reinforcement section is set to 1 / 3 of the length of the blasthole. The ordinary section uses a 70mm diameter charge, and the reinforcement section uses a 90mm diameter charge. The middle interval is blocked with a 1m sealed sandbag. The ordinary section is blasted 0.5s before the reinforcement section. After the bottom reinforcement section is detonated, the secondary crushing of the previously thrown rock mass is completed.

6. A combined blasting control method of directional enhanced throwing blasting and protective layer excavation as claimed in claim 1, characterized in that: The charging structure of the throwing blasting operation area in the step 2 is as follows: the blastholes in the throwing blasting area are charged with water-coupled continuous charging, the blastholes in the throwing blasting area include enhanced throwing holes and energy-replenishing throwing holes, and the charging amount of the energy-replenishing throwing holes is slightly higher than that of the enhanced throwing holes by 10%; the ordinary throwing holes in the protective layer excavation area in the step 3 are charged with air-coupled continuous charging with a diameter of 70mm cartridges, and the inclination angle of the drilling hole is consistent with that of the front throwing blasting area.

7. A combined blasting control method of directional enhanced throwing blasting and protective layer excavation as claimed in claim 1, characterized in that: The buffer holes in the protective layer excavation area in step 3 are as follows: 1 to 2 rows of buffer holes are set after the ordinary casting holes, and the design unit consumption is roughly similar to that of the front row blasting holes by reducing the hole diameter, the hole spacing and the rear row spacing, and adopting uncoupled interval charging of similar pre-splitting holes, and 0.5m of loose slag is backfilled at the bottom of the hole; the pre-splitting zone in the protective layer excavation area in step 3 is designed as double-row pre-splitting blasting holes, with 32mm diameter bamboo strips tied for charging, and the two rows of pre-splitting holes are 0.8m wide. The rear row of pre-splitting holes close to the slope are designed according to traditional pre-splitting blasting design experience, with a distance of 0.6m between holes, and a distance of 0.8m between the front row of pre-splitting holes. The front row of pre-splitting holes are detonated 100ms earlier than the rear row of pre-splitting holes.

8. The combined blasting control method of directional enhanced throwing blasting and protective layer excavation as claimed in claim 1, characterized in that: In the step 2, the blasting operation area adopts mud filling to protect the wall, which is improved to yellow mud slurry filling based on water medium filling to seal the cracks in the hole wall.

9. A combined blasting control method of directional enhanced throwing blasting and protective layer excavation as claimed in claim 1, characterized in that: A special charge gun stick with a plug that can be spliced ​​for deep hole blasting in inclined blastholes is used. The gun stick is made of hard plastic and is divided into 2m sections, which are used in conjunction with straight-through joints.

10. A combined blasting control method of directional enhanced throwing blasting and protective layer excavation as claimed in claim 1, characterized in that: The present invention adopts high-precision digital electronic detonators. When detonating in sections in the main throwing blasting hole, the upper ordinary throwing section detonator is accurately controlled to detonate 0.5s earlier than the lower enhanced throwing section. When double-layer buffer pre-splitting blasting is adopted in the protective layer excavation area, the digital detonators are networked and detonated in the order of front pre-splitting holes → rear pre-splitting holes → throwing blasting holes → buffer holes.

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