Blasting structure and blasting method for steep rock slope

Abstract

The invention relates to a blasting structure and a blasting method for a steep rock slope, the steep rock slope comprises a step to be blasted and a structural surface rock mass, and the step and the structural surface rock mass are integrally connected; the blasting structure comprises a pre-splitting blasting area and a main blasting area, and the pre-splitting blasting area and the main blasting area are sequentially distributed in the horizontal direction in the direction away from the structural face rock mass. The pre-splitting blasting area comprises at least two rows of pre-splitting holes which are sequentially distributed in the direction away from the structural surface rock mass in the horizontal direction, and the first row of pre-splitting holes are formed in the designed excavation contour line of the structural surface rock mass when viewed from the direction away from the structural surface rock mass in the horizontal direction; the main blasting area comprises at least two rows of main blasting holes which are sequentially distributed in the horizontal direction in the direction away from the structural face rock mass. And each row of pre-splitting holes and each row of main blasting holes are arranged in parallel. The overall blasting efficiency is high, the forming quality of the excavated contour surface is high, and the blasting requirement of the ultrahigh steep slope can be well met.

Description

Technical Field

[0001] The invention relates to a blasting structure and a blasting method for a steep rock slope, in particular to a blasting structure and a blasting method for a steep rock slope with a large slope and a weak structural surface, and belongs to the field of water conservancy and hydropower engineering and mining engineering. Background Art

[0002] Areas rich in hydropower resources often have unique mountain and canyon landforms. While providing unique natural conditions for the development of hydropower projects, they also bring unprecedented challenges to engineering construction. The complex geological tectonic movement has caused a large number of weak structural surfaces such as joints, faults, and fissures in the natural rock mass of the slopes in the relevant areas. The rock mass strength is significantly lower than that of the intact rock mass, and it is very sensitive to external dynamic disturbances. When the drilling and blasting method is used to implement slope excavation, the blasting seismic waves stimulated by the explosion of explosives have complex propagation behaviors in the structural surface rock mass, which can easily cause serious surrounding rock damage and unconventional damage, greatly reducing the stability and safety of the slope. Therefore, the design of a reasonable blasting plan is a key factor in ensuring the stability and safety of the entire cycle of ultra-high and steep structural surface slope excavation. The pre-splitting blasting technology in controlled blasting is often used in the excavation of rock mass near the slope surface. By drilling a row of pre-splitting holes on the designed contour surface, through cracks are formed after detonation, reducing the impact of the explosion energy of the main blasting hole on the surrounding rock. However, due to the large scale and steep slope of water conservancy and hydropower projects, complex geological conditions and large amount of explosives in each main blasting hole, conventional pre-splitting blasting often cannot effectively cut off the propagation path of the blasting seismic waves of the main blasting hole, resulting in potential threats to the stability of the slope support unit and surrounding rock. Summary of the invention

[0003] In view of the deficiencies in the prior art, one of the objects of the present invention is to provide a blasting structure for steep rock slopes with good blasting vibration and surrounding rock damage control effects; a second object of the present invention is to provide a blasting structure for steep rock slopes.

[0004] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0005] A blasting structure for a steep rock slope, the steep rock slope comprising a step to be blasted and a structural surface rock mass, the step and the structural surface rock mass being integrally connected; the blasting structure comprising a pre-splitting blasting area and a main blasting area, the pre-splitting blasting area and the main blasting area being sequentially distributed in a horizontal direction in a direction away from the structural surface rock mass; the pre-splitting blasting area comprising at least two rows of pre-splitting holes sequentially distributed in a horizontal direction in a direction away from the structural surface rock mass, the number of pre-splitting holes in each row of pre-splitting holes being at least two, and the first row of pre-splitting holes, viewed in a horizontal direction in a direction away from the structural surface rock mass, being arranged on a designed excavation contour line of the structural surface rock mass; the main blasting area comprising at least two rows of main blasting holes sequentially distributed in a horizontal direction in a direction away from the structural surface rock mass, the number of main blasting holes in each row of main blasting holes being at least two.

[0006] Therefore, before the main blast hole is detonated, the at least two rows of pre-crack holes are detonated first to form a rock crack through layer, and the resulting rock crushing area is used as an isolation zone; then the main blast hole is detonated. Due to the existence of the isolation zone, the surrounding rock damage and blasting vibration during the blasting process can be effectively controlled, so that the structural surface rock contour surface forming effect is good, the surrounding rock damage is small, and the blasting vibration response is weak.

[0007] Furthermore, the pre-splitting blasting area includes two rows of pre-splitting holes, recorded as a front row of pre-splitting holes and a rear row of pre-splitting holes, the front row of pre-splitting holes are arranged on the designed excavation contour line; the spacing between adjacent pre-splitting holes in the front row of pre-splitting holes is smaller than the spacing between adjacent pre-splitting holes in the rear row of pre-splitting holes; preferably, the inclination angle of the pre-splitting holes in the front row of pre-splitting holes is equal to the slope angle (that is, consistent with the inclination angle of the structural surface rock mass), and the pre-splitting holes and main blasting holes in the rear row of pre-splitting holes are straight holes.

[0008] Furthermore, the spacing between adjacent pre-splitting holes in the front row is 0.6-0.8m, and the spacing between adjacent pre-splitting holes in the rear row is 0.8-1.0m. Preferably, the spacing between adjacent pre-splitting holes in the rear row is 1.2-1.3 times the spacing between adjacent pre-splitting holes in the front row. This helps to achieve a good blasting effect, form a regular excavation profile, and effectively control blasting costs.

[0009] Preferably, the front row of pre-splitting holes and the rear row of pre-splitting holes are staggered with each other in a triangular arrangement in the plane space.

[0010] Furthermore, the apertures of the front row pre-splitting holes and the rear row pre-splitting holes are the same and smaller than the aperture of the main blasting holes.

[0011] Furthermore, the spacing between two adjacent rows of pre-splitting holes is 0.8-1.2 m; preferably, the depth of the first row of pre-splitting holes is 0.8-1.2 m deeper than the height of the step.

[0012] Further, the spacing between two adjacent rows of main blastholes is 2.5-3.5m; preferably, the spacing between the holes in the same row of main blastholes is 3.5-4.5m; preferably, the main blasting area includes three rows of main blastholes. Preferably, the depth of the main blasthole is 0.4-0.6 times the height of the step, more preferably 0.45-0.55 times, and even more preferably 0.5 times.

[0013] Furthermore, the rocky steep slope is a steep slope, further a high steep slope, and further an ultra-high steep slope.

[0014] Preferably, each row of pre-splitting holes and each row of main blasting holes are arranged parallel to each other.

[0015] Furthermore, the height of the steps is 15-30 m, and further 20-25 m.

[0016] Furthermore, the height of the structural surface rock mass is 15-30m, and further 20-25m.

[0017] Based on the same inventive concept, the present invention also provides a blasting method for a steep rock slope, comprising the following steps:

[0018] S1. Setting a pre-splitting hole and a main blasting hole on the step to be blasted according to the blasting structure as described above;

[0019] S2, charging and connecting the pre-splitting hole and the main blasting hole;

[0020] S3, detonation;

[0021] Among them, the order of detonation is: each row of pre-crack holes, each row of main blasting holes, among which, each row of pre-crack holes distributed sequentially along the horizontal direction away from the structural surface rock mass are detonated in sequence, and each row of main blasting holes distributed sequentially along the horizontal direction away from the structural surface rock mass are detonated in sequence.

[0022] Furthermore, the pre-splitting holes adopt a single-shot multi-hole detonation method. Furthermore, in the first row of pre-splitting holes, along the horizontal direction, every 3-5 pre-splitting holes form a section, and they are detonated in sequence, with a delay of 30-40ms between sections; in other rows of pre-splitting holes, along the horizontal direction, every 6-8 pre-splitting holes form a section, and they are detonated in sequence, with a delay of 20-30ms between sections; in this way, good blasting can be achieved, and violent rock vibration caused by excessive single detonation charge can be avoided.

[0023] Preferably, 90-110 ms after the blasting of the first row of pre-splitting holes is completed, the second row of pre-splitting holes is detonated again to weaken the superposition effect of stress waves and reduce vibration and surrounding rock damage.

[0024] Furthermore, for the main blast holes adjacent to the pre-splitting holes, single-shot detonation is adopted, with a delay of 45-55ms between holes; for other main blast holes, multiple holes are detonated simultaneously, and the delay time between sections is not less than 50ms.

[0025] Furthermore, the main blasting holes adopt single-shot hole-by-hole detonation and / or single-shot multi-hole detonation. Furthermore, the main blasting area includes 3 rows of main blasting holes distributed in sequence in the horizontal direction away from the structural surface rock mass, the first row of main blasting holes are detonated hole by hole, and the delay between holes is 45-55ms; preferably, in the second row of main blasting holes, along the horizontal direction, every 2-3 pre-crack holes form a section, and they are detonated in sequence section by section, and the delay between sections is 50-100ms; in the third row of main blasting holes, along the horizontal direction, every 3-4 pre-crack holes form a section, and they are detonated in sequence section by section, and the delay between sections is 50-100ms.

[0026] Furthermore, the main blast hole adopts a coupled charge structure. Furthermore, the main blast hole adopts a hole mouth detonation method, the hole mouth uses drilling cuttings, and the blocking length is 3.0m.

[0027] Furthermore, the pre-splitting hole adopts an air-spaced discontinuous charge structure. Preferably, the charge at the bottom of the pre-splitting hole is strengthened, and the hole mouth is blocked with drilling cuttings, and the blocking length is 1.0m.

[0028] Furthermore, the charge amount of each pre-splitting hole in the front row is 6-7kg, and the charge amount of each pre-splitting hole in the rear row is 9-10kg.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The present invention can more accurately control the formation and expansion direction of pre-cracks by setting at least two adjacent rows of pre-crack holes. After the blasting of the first row of pre-crack holes, through cracks are generated, a smooth excavation contour surface is obtained, and a large number of secondary cracks are generated in the rock mass to be excavated; after the blasting of other rows of pre-crack holes, the original cracks are further expanded, and new cracks are generated, forming a wider and more uniform vibration reduction isolation zone, which can effectively improve the vibration reduction and buffering effect. In this way, the blasting energy is efficiently utilized, thereby improving the overall blasting efficiency, and the rock breaking efficiency can be improved, and the blasting vibration and surrounding rock damage are controlled, and the excavation contour surface forming quality is improved, which can better meet the blasting requirements of ultra-high and steep slopes.

[0031] (2) The present invention forms an isolation zone by detonating at least two rows of pre-splitting holes, which can effectively block the propagation of blasting seismic waves from the main blasting holes, thereby significantly reducing the impact of blasting vibration on the stability of the slope rock mass and support units. In addition, compared with traditional single-row pre-splitting blasting, the blasting of the present invention produces less noise and dust, and at the same time has a higher blasting efficiency, which helps to save costs and shorten construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a three-dimensional schematic diagram of the blasting structure of Example 1 of the present invention.

[0033] Figure 2 It is a top view of the blasting structure of Example 1 of the present invention.

[0034] Figure 3 It is a schematic diagram of the charge structure of the pre-splitting hole of Example 1 of the present invention.

[0035] Figure 4 It is a schematic diagram of the charging structure of the main blasthole of Example 1 of the present invention.

[0036] Figure 5 It is a schematic diagram of the arrangement of acoustic wave test holes for rock damage in Example 1 of the present invention and related comparative examples, wherein the left figure is a cross-sectional view and the right figure is a view of the rock mass facing the structural surface.

[0037] Figure 6 is the total velocity time curve of the measuring point, where Figure 6 a corresponds to Example 1, Figure 6 b corresponds to proportion 1, Figure 6 c corresponds to proportion 2.

[0038] Figure 7 This is a simplified structural diagram of the blasting structure of Example 1 of the present invention.

[0039] In the figure, 1-structural surface rock mass, 2-front row pre-crack holes, 3-back row pre-crack holes, 4-main blasting hole, 5-step. DETAILED DESCRIPTION

[0040] The present invention will be described in detail below in conjunction with the embodiments. It should be noted that the embodiments and features of the embodiments of the present invention can be combined with each other without conflict. For the convenience of description, if the words "upper", "lower", "left" and "right" appear in the following, they only indicate that the upper, lower, left and right directions are consistent with the drawings themselves, and do not limit the structure.

[0041] Example 1

[0042] See also Figure 1-4 , Figure 7 The designed mining height of the slope of a hydropower station material field is close to 400m. The slope includes steps to be blasted and structural surface rock mass (the inclination angle is 90°, that is, a vertical slope). The steps and structural surface rock mass are connected as a whole, and the step height is 20m. The main rock in the discharge area is slightly weathered to fresh hornblende schist, with an average dry density of 2.81g / cm 3 The dry uniaxial compressive strength is 102.4MPa, and the design adopts drilling and blasting method for excavation.

[0043] The blasting structure of this embodiment includes a pre-splitting blasting area and a main blasting area, and the pre-splitting blasting area and the main blasting area are sequentially distributed along the horizontal direction toward the direction away from the structural surface rock mass; the pre-splitting blasting area includes 2 rows of pre-splitting holes sequentially distributed along the horizontal direction toward the direction away from the structural surface rock mass, and the number of pre-splitting holes in each row of pre-splitting holes is multiple, and when viewed along the horizontal direction toward the direction away from the structural surface rock mass, the first row of pre-splitting holes is arranged on the designed excavation contour line of the structural surface rock mass; the main blasting area includes 3 rows of main blasting holes sequentially distributed along the horizontal direction toward the direction away from the structural surface rock mass, and the number of main blasting holes in each row of main blasting holes is multiple; each row of pre-splitting holes and each row of main blasting holes are arranged parallel to each other.

[0044] The blasting method of this embodiment is as follows:

[0045] Step i: Figure 2 As shown, on the designed excavation contour line, a row of front pre-splitting holes with a hole spacing S1 = 0.8m is arranged, and the front pre-splitting holes are straight holes.

[0046] Step ii, using the front row pre-splitting holes described in step i as the directional expansion direction and compensation space of the blasting cracks generated by the rear row pre-splitting holes, and arranging the rear row pre-splitting holes on the working surface; wherein, the hole spacing S1 of the front row pre-splitting holes is 0.8m, the hole spacing S2 of the rear row pre-splitting holes is 1.0m, and the row spacing W1 between the front row pre-splitting holes and the rear row pre-splitting holes is 1.0m.

[0047] Step iii, arranging the first row of main blasting holes in the main blasting area, wherein the hole spacing of the first row of main blasting holes is S3=4.0m, and the row spacing between the first row of main blasting holes and the rear row of pre-splitting holes is W2=3.0m.

[0048] Step iv, using the first row of main blastholes described in step iii as the free surface and throwing space, arrange the second row of main blastholes, wherein the hole spacing S4 of the second row of main blastholes is 4.0m, and the row spacing W3 between the second row of main blastholes and the first row of main blastholes is 3.0m.

[0049] Step v, using the second row of main blastholes described in step iii as the free surface and throwing space, and using the rock crushing zone produced by the blasting of the front row pre-splitting holes and the rear row pre-splitting holes described in steps i and ii as the isolation zone, arranging the third row of main blastholes, wherein the hole spacing S5 of the third row of main blastholes is 4.0m, and the row spacing W4 between the third row of main blastholes and the second row of main blastholes is 3.0m.

[0050] Step vi, design the blasting sequence. Specifically, in the horizontal direction, the front row pre-splitting holes are divided into sections of 4 holes each, and are detonated in sequence section by section with a delay of 35ms between sections; the rear row pre-splitting holes are divided into sections of 7 holes each, and are detonated in sequence section by section with a delay of 25ms; the rear row pre-splitting holes are detonated 100ms after the front row pre-splitting holes are detonated.

[0051] Looking horizontally, the first row of main blast holes are detonated one by one, with a delay time of 50ms between holes; the second row of main blast holes are divided into sections of 2 holes each, and they are detonated in sequence with a delay time of 50ms; the third row of main blast holes are divided into sections of 3 holes each, and they are detonated in sequence with a delay time of 50ms. Figure 4 As shown, all main blast holes adopt a coupled charging structure, and the charge amount of emulsion explosive is 65kg.

[0052] Step vii. According to the charge amount and delay time of each hole described in step vi and step vii, an electronic digital detonator is buried in each pre-crack hole and the main blast hole, and a detonating cord is used for network connection, and then remote control detonation is implemented.

[0053] Among them, the front and rear pre-splitting holes and main blasting holes are vertical holes, the diameter of the front and rear pre-splitting holes is 90mm, the diameter of various main blasting holes is 115mm, the depth of the front and rear pre-splitting holes is 1m deeper than the step with a height of 20m, and the depth of the main blasting holes is 10m. Figure 3 As shown, the front and rear pre-splitting holes adopt an air-spaced discontinuous charge structure, the charge at the bottom of the hole is strengthened, and the hole mouth is blocked with drilling cuttings for 1.0m. Among them, the charge of a single hole in the front pre-splitting hole is 6.5kg, and the charge of a single hole in the rear pre-splitting hole is 9.5kg. Figure 4 As shown, the main blasthole is coupled charged, and the hole mouth is blocked with drilling cuttings for 3.0m.

[0054] Comparative Example 1

[0055] Example 1 was repeated, with the main differences being that: the first row of main blastholes was detonated in a single hole, with a delay time of 25ms between holes. The second row of main blastholes was divided into a section of 3 holes, which were detonated section by section, with a delay time of 25ms between sections. The third row of main blastholes was divided into a section of 5 holes, which were detonated section by section, with a delay time of 25ms between sections.

[0056] Comparative Example 2

[0057] Example 1 was repeated, with the main difference being that only a single row of pre-splitting holes was arranged, and all pre-splitting holes were detonated simultaneously. Three rows of main blasting holes were divided into sections of 3 holes each, and detonated section by section, with a delay time of 50ms between sections.

[0058] Comparative Example 3

[0059] Example 1 is repeated, with the main difference being that the hole spacing S1 of the front row of pre-crack holes is 0.5 m. At this time, the unit consumption of explosives in the rock mass in the pre-crack hole area increases, thereby increasing the surrounding rock damage and improving the vibration intensity.

[0060] Example 2

[0061] Example 1 was repeated, with the main difference being that the hole spacing S1 of the front row of pre-splitting holes was 0.6 m.

[0062] Comparative Example 4

[0063] Example 1 was repeated, with the main difference being that the spacing between the front row of pre-cracked holes was S1 = 0.9 m. The results showed that the regularity of the excavation profile was not ideal at this time, and the cracks along the blasthole line could not be linearly connected, and the surrounding rock showed more significant over-excavation and under-excavation.

[0064] Comparative Example 5

[0065] Example 1 is repeated, with the main difference being that the hole spacing S2 of the rear pre-splitting holes is 0.7 m. At this time, the unit consumption of explosives in the rock mass in the pre-splitting hole area increases, thereby increasing the surrounding rock damage and the vibration intensity.

[0066] Example 3

[0067] Example 1 was repeated, with the main difference being that the hole spacing S2 of the rear row of pre-splitting holes was 0.8 m.

[0068] Comparative Example 6

[0069] Example 1 was repeated, with the main difference being that the spacing between the rear pre-crack holes was S2 = 1.1 m. The results showed that the regularity of the excavation profile was not ideal, and the cracks along the blasthole line could not penetrate linearly, and the surrounding rock showed more significant over-excavation and under-excavation.

[0070] Comparative Example 7

[0071] Example 1 was repeated, with the main difference being that the row spacing W1 between the front row pre-splitting holes and the rear row pre-splitting holes was = 0.7 m.

[0072] Example 4

[0073] Example 1 was repeated, with the main difference being that the row spacing W1 between the front row pre-splitting holes and the rear row pre-splitting holes was 0.8 m.

[0074] Example 5

[0075] Example 1 was repeated, with the main difference being that the row spacing W1 between the front row pre-splitting holes and the rear row pre-splitting holes was 1.2 m.

[0076] Comparative Example 8

[0077] Example 1 was repeated, with the main difference being that the row spacing W1 between the front row pre-splitting holes and the rear row pre-splitting holes was 1.3 m.

[0078] In order to evaluate the pre-splitting effect under different blasting implementation schemes, the following Figure 5The blasting vibration monitoring and acoustic wave test arrangement diagram shown in the embodiment 1-5, comparative example 1-8 blasting schemes and the surrounding rock drilling acoustic wave velocity after blasting are tested. At the same time, the excavation profile surface generated after the implementation of the embodiment and comparative example scheme is scanned using a three-dimensional laser scanner to obtain the semi-porosity remaining on the slope surface (generally, the larger the semi-porosity, the better, so that the excavation profile surface is more regular, and there will be no obvious over-excavation or under-excavation). The vibration velocity test results and rock mass acoustic wave test results are shown in Tables 1 and 2, respectively, and the semi-porosity test results are shown in Table 3.

[0079] Table 1 Blasting vibration velocity PPV (unit: cm·s) under different excavation schemes -1 )

[0080]

[0081] Table 2 Rock mass damage thickness under different excavation schemes (unit: m)

[0082]

[0083] Table 3 Semi-porosity of excavation profile under different excavation schemes (unit: %)

[0084]

[0085]

[0086] From the semi-porosity measurement results, it can be seen that: compared with comparative examples 3, 4 and embodiment 2, Example 1 shows that as the spacing between the front row of pre-crack holes increases, the semi-holes first increase and then decrease. Controlling the appropriate hole spacing helps to obtain a higher semi-porosity and avoid or reduce over-excavation or under-excavation. Compared with comparative example 1, Example 1 reduces the delay time between the pre-crack holes and the main blasting holes. Due to the enhanced superposition of stress waves, the semi-porosity of the slope surface decreases. Compared with comparative example 2, Example 1 reduces the number of pre-crack holes to 1 row, and the damage to the surrounding rock caused by the blasting of the main blasting holes increases, resulting in a decrease in semi-porosity. Compared with comparative examples 5, 6 and embodiment 3, Example 1 shows a gradual decrease in the semi-porosity as a whole with the increase of the subsequent row of pre-crack holes. Compared with comparative examples 7, 8 and embodiments 4 and 5, Example 1 shows a trend of increasing first and then decreasing. When the spacing between the pre-crack holes is 1.0m, the semi-porosity is the largest, reaching 94.9%.

[0087] It can be seen from the results of the blasting particle vibration velocity that: compared with Comparative Example 1 (main blasting hole delay time of 25ms), Example 1 shows that increasing the delay time between the main blasting holes and between the sections to 50ms can effectively reduce the blasting vibration, and the vibration velocity of the same measuring point decreases by 36.0% to 67.8%. Compared with Comparative Example 2 (single-layer pre-splitting hole blasting excavation scheme), due to the use of double-row pre-splitting hole blasting for the structural surface rock mass, the blasting particle vibration velocity in Example 1 decreases by 39.9% to 61.1%, achieving effective control of the dynamic response of the surrounding rock caused by the blasting seismic wave. Compared with Comparative Example 3, Comparative Example 4 and Example 2, Example 1 shows that the particle vibration velocity gradually decreases with the increase of the hole spacing of the front row pre-splitting holes, and the vibration velocity changes by a large amplitude. Compared with Comparative Example 5, Comparative Example 6 and Example 3, Example 1 shows that the particle vibration velocity is negatively correlated with the hole spacing of the rear row pre-splitting holes, but the particle vibration velocity changes by a small amplitude after the hole spacing of the rear row pre-splitting holes changes. The comparison between Example 1 and Comparative Example 7, Comparative Example 8, Example 4 and Example 5 shows that as the spacing between the front and rear rows of pre-crack holes gradually increases from 0.7 m to 1.3 m, the particle vibration velocity tends to gradually decrease as a whole, indicating that as the spacing between the pre-crack holes increases, the explosive energy acting on the rock mass decreases accordingly.

[0088] It can be seen from the results of the drilling sonic test that compared with Comparative Example 1, the surrounding rock damage thickness in Example 1 is reduced by 6.8% to 31.1%, and compared with Comparative Example 2, the surrounding rock damage thickness in Example 1 is reduced by 9.2% to 37.2%, achieving effective control of rock damage on the result surface of the high and steep slope. Compared with Examples 2-5 and Comparative Examples 3-8, Example 1 shows that the surrounding rock damage thickness is negatively correlated with the spacing between the front row pre-crack holes and the spacing between the rear row pre-crack holes, that is, as the spacing between the pre-crack holes decreases, the surrounding rock damage thickness gradually increases. In addition, as the spacing between the double-row pre-crack holes increases, the surrounding rock damage thickness gradually decreases.

[0089] The contents explained in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

Claims

1. A blasting structure for a steep rock slope, wherein the steep rock slope comprises a step to be blasted and a structural surface rock mass, wherein the step and the structural surface rock mass are integrally connected; characterized in that: The blasting structure comprises a pre-splitting blasting area and a main blasting area, and the pre-splitting blasting area and the main blasting area are sequentially distributed along the horizontal direction toward the direction away from the structural surface rock mass; the pre-splitting blasting area comprises at least 2 rows of pre-splitting holes sequentially distributed along the horizontal direction toward the direction away from the structural surface rock mass, and the number of pre-splitting holes in each row of pre-splitting holes is at least 2, and when viewed along the horizontal direction toward the direction away from the structural surface rock mass, the first row of pre-splitting holes is arranged on the designed excavation contour line of the structural surface rock mass; the main blasting area comprises at least 2 rows of main blasting holes sequentially distributed along the horizontal direction toward the direction away from the structural surface rock mass, and the number of main blasting holes in each row of main blasting holes is at least 2.

2. The blasting structure according to claim 1, characterized in that: The pre-splitting blasting area includes two rows of pre-splitting holes, denoted as a front row of pre-splitting holes and a rear row of pre-splitting holes, wherein the front row of pre-splitting holes is arranged on a designed excavation contour line; the spacing between adjacent pre-splitting holes in the front row of pre-splitting holes is smaller than the spacing between adjacent pre-splitting holes in the rear row of pre-splitting holes; preferably, the inclination angle of the pre-splitting holes in the front row of pre-splitting holes is equal to the slope angle, and the pre-splitting holes and the main blasting holes in the rear row of pre-splitting holes are both straight holes.

3. The blasting structure according to claim 2, characterized in that: The spacing between adjacent pre-splitting holes in the front row is 0.6-0.8 m, and the spacing between adjacent pre-splitting holes in the rear row is 0.8-1.0 m. Preferably, the spacing between adjacent pre-splitting holes in the rear row is 1.2-1.3 times the spacing between adjacent pre-splitting holes in the front row.

4. The blasting structure according to claim 1, characterized in that: The spacing between two adjacent rows of pre-splitting holes is 0.8-1.2 m; preferably, the depth of the first row of pre-splitting holes is 0.8-1.2 m deeper than the height of the step.

5. The blasting structure according to claim 1, characterized in that: The spacing between two adjacent rows of main blast holes is 2.5-3.5m; preferably, the spacing between holes in the same row of main blast holes is 3.5-4.5m; preferably, the main blasting area includes 3 rows of main blast holes; preferably, each row of pre-splitting holes and each row of main blast holes are arranged parallel to each other.

6. A blasting method for steep rock slopes, characterized in that: The steps include: S1. A blasting structure according to any one of claims 1 to 5 is provided with a pre-splitting hole and a main blasting hole on the step to be blasted; S2, charging and connecting the pre-splitting hole and the main blasting hole; S3, detonation; Among them, the order of detonation is: each row of pre-crack holes, each row of main blasting holes, among which, each row of pre-crack holes distributed sequentially along the horizontal direction away from the structural surface rock mass are detonated in sequence, and each row of main blasting holes distributed sequentially along the horizontal direction away from the structural surface rock mass are detonated in sequence.

7. The blasting method according to claim 6, characterized in that: In the first row of pre-splitting holes, every 3-5 pre-splitting holes form a section in the horizontal direction, and they are detonated in sequence, with a delay of 30-40ms between sections; in the other rows of pre-splitting holes, every 6-8 pre-splitting holes form a section in the horizontal direction, and they are detonated in sequence, with a delay of 20-30ms between sections; Preferably, the second row of pre-splitting holes is detonated 90-110 ms after the blasting of the first row of pre-splitting holes is completed.

8. The blasting method according to claim 6, characterized in that: The main blasting area includes 3 rows of main blasting holes which are sequentially distributed in the horizontal direction toward the direction away from the structural surface rock mass. The main blasting holes in the first row are detonated hole by hole, with a delay of 45-55ms between holes. Preferably, in the second row of main blasting holes, as viewed in the horizontal direction, every 2-3 pre-crack holes form a section, which are detonated sequentially section by section, with a delay of 50-100ms between sections. In the third row of main blasting holes, as viewed in the horizontal direction, every 3-4 pre-crack holes form a section, which are detonated sequentially section by section, with a delay of 50-100ms between sections.

9. The blasting method according to claim 6, characterized in that: The main blast hole adopts a coupled charging structure.

10. The blasting method according to claim 6, characterized in that: The pre-splitting hole adopts an air-spaced discontinuous charging structure.

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