Cutting blasting method

Abstract

The invention discloses a cut blasting method, and relates to the technical field of tunneling, a first cut hole extends from a rock mass area related to a current excavation cycle to a rock mass area related to a next excavation cycle, after a first excavation cycle is completed, a sub-surface has a temporary cavity in each subsequent excavation cycle process, and a second cut hole extends from the rock mass area related to the next excavation cycle to the rock mass area related to the next excavation cycle. The crustal stress on the boundary of the temporary cavity is released to cause the crustal stress redistribution of the rock mass in the region involved in the next excavation cycle, so that the temporary cavity forms a pressure stress concentration region in the minimum principal stress direction, and the strength of the rock mass in the region involved in the next excavation cycle is reduced; the temporary cavity and the rock mass damage area can be used for assisting in completing rock breaking excavation in the subsequent excavation cycle, and the amount of explosives needed in the whole excavation process is reduced; and the blasting parameters of the slotting hole group required by the next excavation cycle can be adjusted in a targeted manner according to the geometric parameters, so that the problem that the slotting area is formed too large or too small due to blind reduction of the explosive quantity is solved, and the forming quality of the slotting area is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel excavation blasting, in particular to a cut blasting method. Background Art

[0002] Compared to shallow rock masses, deeply buried rock masses generally exhibit high geostress characteristics due to the combined effects of tectonic and self-weight stresses. Currently, drilling and blasting remains the primary construction method for deep tunnel excavation due to its economical and efficient nature. In full-face millisecond delay blasting, blastholes are typically arranged from the inside out in the order of slot holes, collapse holes, and peripheral holes. The slot holes are detonated first, forming a cavity on the excavation face, creating a new free surface for subsequent blasting. Therefore, the blasting effect of the slot holes directly affects the subsequent blasting results and the efficiency of the cycle footage.

[0003] However, under high geostress conditions, slot blasting in rock masses presents significant technical challenges. Numerous engineering practices have demonstrated that the strong constraints of geostress in high geostress rock masses significantly inhibit the propagation of blast-induced cracks, preventing the blasting cracks from effectively penetrating the rock mass and making it difficult to form the slot cavity. While using excessive amounts of explosives can effectively penetrate the rock mass, this can also lead to explosive waste.

[0004] Therefore, how to improve the forming quality of the cut cavity and reduce the amount of explosives used has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] The object of the present invention is to provide a cut blasting method to improve the forming quality of the cut cavity and reduce the amount of explosives used.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a slot blasting method, which comprises the following steps:

[0008] Step S1, arranging the cut hole group required for the current excavation cycle on the stone surface;

[0009] The excavation cycle includes drilling, charging, blasting and slagging on the subgrade surface; the slot hole group includes a plurality of first slot holes, and the first slot holes extend from the rock mass area involved in the current excavation cycle to the rock mass area involved in the next excavation cycle;

[0010] Step S2, detonating the cut hole group required for the current excavation cycle;

[0011] Step S3, determining the geometric parameters of the rock mass damage zone formed on the subgrade surface during the previous excavation cycle;

[0012] Wherein, the geometric parameters include the position of the rock mass damage zone and the volume of the rock mass damage zone;

[0013] Step S4, arranging the slot hole group required for the next excavation cycle on the stone surface, and adjusting the blasting parameters of the slot hole group required for the next excavation cycle according to the geometric parameters;

[0014] The blasting parameters include the number of the first slot holes in the slot hole group, and / or the spacing between adjacent first slot holes, and / or the charge amount of the first slot holes;

[0015] Step S5, looping through steps S2 to S4 until the construction is completed.

[0016] Preferably, the depth of the first cut hole is the sum of the cycle footage of the current excavation cycle and the cycle footage of the next excavation cycle.

[0017] Preferably, the slot hole group further includes a plurality of second slot holes, and the second slot holes and the first slot holes are arranged in sequence along the excavation direction of the subgrade face, and the depth of the second slot holes is the cycle feed of the current excavation cycle.

[0018] Preferably, when the distance between the first groove hole and the second groove hole is greater than a preset value, the groove hole group further includes a third groove hole located between the first groove hole and the second groove hole, and the depth of the third groove hole is greater than the depth of the second groove hole and less than the depth of the first groove hole.

[0019] Preferably, adjusting the blasting parameters required for the next excavation cycle in step S4 includes: adjusting the charge of at least the first slot hole, the second slot hole, and the first slot hole among the third slot holes according to a charge adjustment formula;

[0020] The charge adjustment formula is:

[0021] Where η is the charge adjustment coefficient; η0 is the charge reference value, 0.4<η0<1.0; R is the actual radius of the rock damage zone; R0 is the preset radius of the rock damage zone; α is the rock sensitivity coefficient, 0.5<α<1.5.

[0022] Preferably, when the actual radius of the rock damage zone in two consecutive excavation cycles is smaller than the preset radius of the rock damage zone, the blasting parameters of the cut hole group required for the next excavation cycle are adjusted.

[0023] Preferably, the extending direction of the groove hole group in the step S1 and the step S4 is inclined to the stone surface.

[0024] Preferably, in step S1 and step S4, all the first cutout holes on the stone surface are wedge-shaped and symmetrically distributed with the maximum principal stress direction of the stone surface as the symmetry axis.

[0025] Preferably, the cutout hole groups are arranged along the direction of maximum principal stress of the substructure surface.

[0026] Preferably, the slot blasting method includes: before arranging the slot hole group in step S1, using a stress relief method, a hydraulic fracturing method or an acoustic emission method to determine the maximum principal stress direction on the subsurface.

[0027] Compared with the prior art, the present invention has achieved the following technical effects:

[0028] The slot blasting method of the present invention includes the following steps: step S1, arranging a slot hole group required for a current excavation cycle on the stone surface; the excavation cycle includes drilling, charging, blasting and slagging on the stone surface; the slot hole group includes a plurality of first slot holes, and the first slot holes extend from a rock mass area involved in the current excavation cycle to a rock mass area involved in a next excavation cycle; step S2, detonating the slot hole group required for the current excavation cycle; step S3, determining geometric parameters of a rock mass damage zone formed on the stone surface in the previous excavation cycle; the geometric parameters include the position and volume of the rock mass damage zone; step S4, arranging a slot hole group required for a next excavation cycle on the stone surface, and adjusting blasting parameters of the slot hole group required for the next excavation cycle according to the geometric parameters; the blasting parameters include the number of first slot holes in the slot hole group, and / or the spacing between adjacent first slot holes, and / or the charge amount of the first slot holes; step S6, repeating steps S2 to S4 until the construction is completed;

[0029] Among them, because the first slot hole extends from the rock mass area involved in the current excavation cycle to the rock mass area involved in the next excavation cycle, after completing the first excavation cycle, a temporary cavity generated by the previous excavation cycle will exist on the sub-face during each subsequent excavation cycle (the temporary cavity is specifically formed by the blasting of the first slot hole in the previous excavation cycle. The temporary cavity means that the cavity does not exist continuously. The temporary cavity formed by the previous excavation cycle will disappear after the completion of the next excavation cycle). The release of the ground stress on the boundary of the temporary cavity will cause the ground stress of the rock mass in the area involved in the next excavation cycle to be redistributed, so that the temporary cavity forms a compressive stress concentration area in the direction of the minimum principal stress, and causes damage to the rock mass in the area involved in the next excavation cycle, which significantly reduces the rock mass strength in the area involved in the next excavation cycle. This allows the subsequent excavation cycle to use the temporary cavity and the rock mass damage area to assist in completing rock breaking excavation, thereby reducing the amount of explosives required in the entire excavation process and reducing the excavation cost.

[0030] Furthermore, the present invention can specifically adjust the blasting parameters of the cut hole group required for the next excavation cycle according to the geometric parameters of the rock mass damage zone, thereby reducing the problem of the cut cavity being too large or too small due to blindly reducing the amount of explosives, and ensuring the forming quality of the cut cavity (the cut cavity refers to the cavity formed on the stone surface after the cut hole group is blasted and slag is discharged);

[0031] In summary, the present invention not only reduces the amount of explosives required for slot blasting and lowers excavation costs, but also effectively ensures the forming quality of the slot cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 The diagram is a schematic diagram of the stress distribution on the stone surface and the distribution of blast holes such as slot holes, drop holes, and light blast holes;

[0034] Figure 2 This is a schematic diagram of the arrangement of the cut hole group in the first excavation cycle of the cut area;

[0035] Figure 3 for Figure 2 sectional view of

[0036] Figure 4 Schematic diagram of the temporary cavity and rock damage area after the first excavation cycle in the cut area;

[0037] Figure 5 for Figure 4 sectional view of

[0038] Figure 6 This is a schematic diagram of the arrangement of the cut hole group in the second excavation cycle in the cut area;

[0039] Figure 7 for Figure 6 sectional view of

[0040] Among them, 1. The first slot hole; 2. The second slot hole; 3. The third slot hole; 4. The stone surface; 5. The cycle footage line; 6. The temporary cavity; 7. The rock damage area; 8. The slot area; 9. The collapse area; 10. The light explosion layer. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] like Figures 1 to 7 As shown, the present invention discloses a slot blasting method, wherein the slot blasting method comprises the following steps: step S1, arranging a slot hole group required for the current excavation cycle on the stone face 4; the excavation cycle comprises drilling, charging, blasting and slagging on the stone face 4; the slot hole group comprises a plurality of first slot holes 1, and the first slot holes 1 extend from the rock mass area involved in the current excavation cycle to the rock mass area involved in the next excavation cycle; step S2, detonating the slot hole group required for the current excavation cycle; step S3, determining the slot hole group required for the previous excavation cycle in the rock mass area involved in the previous excavation cycle in the rock mass area involved in the next ... The geometric parameters of the rock damage zone 7 formed on the stone face 4 are as follows: the geometric parameters include the position and volume of the rock damage zone 7; step S4: arranging the slot hole group required for the next excavation cycle on the stone face 4, and adjusting the blasting parameters of the slot hole group required for the next excavation cycle according to the geometric parameters; the blasting parameters include the number of first slot holes 1 in the slot hole group, and / or the spacing between adjacent first slot holes 1, and / or the charge amount of the first slot holes 1; step S6: repeating steps S2 to S4 until the construction is completed;

[0044] Among them, because the first slot hole 1 extends from the rock mass area involved in the current excavation cycle to the rock mass area involved in the next excavation cycle, after completing the first excavation cycle, the sub-face 4 has a temporary cavity 6 generated by the previous excavation cycle in each subsequent excavation cycle (the temporary cavity 6 is specifically formed by the blasting of the first slot hole 1 in the previous excavation cycle. The temporary cavity 6 means that the cavity does not exist continuously. The temporary cavity 6 formed in the previous excavation cycle will disappear after the completion of the next excavation cycle). The release of the ground stress on the boundary of the temporary cavity 6 will cause the ground stress of the rock mass in the area involved in the next excavation cycle to be redistributed, so that the temporary cavity 6 forms a compressive stress concentration area in the direction of the minimum principal stress, and causes damage to the rock mass in the area involved in the next excavation cycle, which significantly reduces the rock mass strength in the area involved in the next excavation cycle. This allows the subsequent excavation cycle to assist in completing rock breaking excavation with the help of the temporary cavity 6 and the rock damage area 7, thereby reducing the amount of explosives required in the entire excavation process.

[0045] Moreover, the present invention can specifically adjust the blasting parameters of the slot hole group required for the next excavation cycle according to the geometric parameters of the rock damage zone 7, thereby reducing the problem of the slot area 8 being too large or too small due to blindly reducing the amount of explosives, and ensuring the forming quality of the slot cavity (the slot cavity refers to the cavity formed after the slot hole group is blasted); in summary, the present invention not only reduces the amount of explosives required for slot blasting and reduces excavation costs, but also effectively ensures the forming quality of the slot cavity.

[0046] The tunnel excavation process is actually a repeated cycle of drilling, charging, blasting and slag removal. Therefore, the steps including drilling, charging, blasting and slag removal are referred to as excavation cycles. Among them, the number of excavation cycles performed can be called the nth excavation cycle (n≥1).

[0047] like Figure 1 As shown, the slot blasting method includes determining the direction and magnitude of the maximum principal stress, as well as the direction and magnitude of the minimum stress, on the tunnel face 4 (also known as the working face) before arranging the slot holes in step S1. The slot holes are then arranged along the direction of the maximum principal stress. Because the direction of the maximum principal stress is the most prone to deformation on the tunnel face 4, this arrangement effectively reduces the amount of explosives required to produce a slot cavity of the same quality, thereby reducing construction costs.

[0048] The direction and magnitude of the maximum principal stress, as well as the direction and magnitude of the minimum principal stress, on the tunnel face 4 (i.e., the excavation surface of the tunnel) can be determined by stress relief methods, hydraulic fracturing, acoustic emission, or other methods. The stress relief method refers to the hollow inclusion stress relief method. The hydraulic fracturing method assumes that one of the three principal stresses of geostress is vertical, i.e., in the direction of the deadweight stress, and the other two are horizontal. Therefore, high-pressure water is pumped into a test section separated by a packer to crack the borehole wall. Based on the theory of elastic mechanics, the magnitude and direction of the maximum and minimum principal stresses in the horizontal plane can be determined. The acoustic emission method establishes relevant testing and analysis theories based on the Kaiser effect exhibited by rocks under certain pressure conditions. This means that during repeated loading of a rock specimen, if the stress does not exceed the previous maximum stress, little or no acoustic emission is generated. Only when the loading stress exceeds the previous maximum stress does significant acoustic emission occur. Among them, since the stress relief method, hydraulic fracturing method and acoustic emission method are all existing technologies, the equipment used to implement the above methods and the specific operation procedures are not described here in detail.

[0049] Specifically, the depth of the first slot hole 1 is the sum of the cyclic advance of the current excavation cycle and the cyclic advance of the next excavation cycle. The cyclic advance refers to the distance the stone face 4 needs to advance forward after the current excavation cycle is completed. This not only forms a temporary cavity 6 on the stone face 4 of the next excavation cycle, creating conditions for the subsequent use of stress redistribution to assist rock breaking, but also ensures the forming quality of the slot cavity, reduces the risk of the first slot hole 1 being too deep, resulting in an oversized slot cavity, and causing hazards such as rock bursts and landslides. As long as the first slot hole 1 covers the cyclic advance of the current excavation cycle, and the depth of the first slot hole 1 is greater than the cyclic advance of the current excavation cycle, but not greater than the sum of the cyclic advance of the current excavation cycle and the cyclic advance of the next excavation cycle, the depth of the first slot hole 1 can also be within other numerical ranges.

[0050] like Figure 2 、 Figure 3 As shown, the slot hole group in the present invention also includes a plurality of second slot holes 2. The second slot holes 2 and the first slot holes 1 are arranged in sequence along the excavation direction of the stone face 4. The depth of the second slot holes 2 is the cycle feed of the current excavation cycle. The second slot holes 2 blast out a slot cavity when there is only one free surface, namely the stone face 4, in the first excavation cycle. This adds a free surface for the blasting of the collapse hole and the smooth blasting hole, and provides a rock expansion compensation space, reducing the clamping effect of the rock mass on the blasting of the collapse hole and the smooth blasting hole, creating favorable conditions for the blasting of the collapse hole and the smooth blasting hole. At this time, the first slot hole 1 expands the size of the slot cavity formed by the blasting of the current excavation cycle, namely the second slot hole 2, and forms a temporary cavity 6 on the stone face 4 of the next excavation cycle, creating conditions for the subsequent use of stress redistribution to assist rock breaking.

[0051] When the distance between the first slot hole 1 and the second slot hole 2 is large, resulting in excessive charging of the first slot hole 1 and / or the second slot hole 2, the slot hole group also includes a third slot hole 3 arranged between the first slot hole 1 and the second slot hole 2. The depth of the third slot hole 3 is greater than the depth of the second slot hole 2 and less than the depth of the first slot hole 1. By setting the third slot hole 3, the problem of excessive charging of the first slot hole 1 and / or the second slot hole 2 due to the large distance between the first slot hole 1 and the second slot hole 2 is reduced, which causes large dynamic disturbance to the rock mass and triggers disasters such as rock bursts or landslides.

[0052] Specifically, the depth of the third groove hole 3 may be 1.5 times the depth of the first groove hole 1 ; and the arrangement depths of the first groove hole 1 , the second groove hole 2 and the third groove hole 3 are allowed to have an error within 10%.

[0053] like Figure 2 、 Figure 3 As shown, the second cut holes 2, the third cut holes 3, and the first cut hole 1 form the inner, middle, and outer layers of cut holes, respectively. The distance between each layer of cut holes (i.e., the outer, middle, and inner layers), as well as the number of first cut holes 1, second cut holes 2, and third cut holes 3, are designed based on the target size of the temporary cavity 6 (i.e., the desired temporary cavity 6). The larger the distance between each layer of cut holes or the greater the number of cut holes per layer, the larger the volume of the resulting temporary cavity 6 and the larger the rock damage zone 7 after stress redistribution. Blasting parameters also include parameters such as the spacing between adjacent layers of cut holes and the number of cut holes per layer.

[0054] To fully utilize the redistribution of ground stress to assist rock breaking while preventing ground stress from affecting unnecessary rock mass, the distance between adjacent slot holes in the outer, middle, and inner layers can be set to 40 cm. Each layer of slot holes is symmetrically arranged along the direction of the major principal stress, with four slot holes on each side, and four slot holes on each side, with a spacing of 0.9 m between adjacent slot holes. Detonation can be carried out using millisecond-delay blasting, a full-section excavation method. Millisecond-delay blasting can be achieved using millisecond detonators or other millisecond-delay detonation devices. The detonation sequence is inner slot hole → middle slot hole → outer slot hole, with a delay time of 50 milliseconds between each layer. After the outer layer slot holes, the middle layer slot holes and the inner layer slot holes are arranged, the caving holes and the smooth blasting holes are arranged in the caving area 9 and the smooth blasting layer 10 respectively. The caving holes are arranged in a plum blossom pattern in the caving area 9, with a hole diameter of 48 mm, a hole depth of 0.9-1.1 times the current cycle footage, and a hole spacing of 0.8-1.2 m. Multiple rows of caving holes are arranged in sequence along the excavation direction of the sub-face 4, with a row spacing of 0.7-0.9 m between adjacent rows of caving holes, and a charge coefficient controlled at 55% to 65%. %, using a continuous coupled charge structure (coupled charge means no gap is left between the charge and the blasthole), with a plugging length of no less than 25% of the hole depth (blastholes can be plugged using structures such as taphole mud or blister mud). The smooth blasting layer 10 is arranged with 32mm diameter smooth blasting holes, with the hole spacing increased to 0.4-0.6m. The linear charge density is controlled at 180-220g / m. An air-spaced charge structure is used (charge / air column length ratio of 1:2), with a 0.8-1.2m reinforced plugging section reserved at the hole mouth. The detonation time difference between the caving hole and the smooth blasting hole is set: the caving hole lags behind the slot hole by 100-150ms, and the smooth blasting hole lags behind the caving hole by 50-75ms.

[0055] In addition, after the blasting in the previous excavation cycle is completed, the rock mass in the footage of the previous cycle is removed, and the degree of rock damage is assessed using acoustic wave detection or drilling detection methods. Specifically, the acoustic wave detection method can use acoustic wave detection equipment with a single-transmitter, dual-receiver transducer to scan the rock mass around the temporary cavity 6 created on the subgrade face 4 during the previous excavation cycle (for example, grid scanning with a measurement point spacing of 0.5m). Areas with a wave velocity attenuation rate greater than 15% are rock damage areas 7. The acoustic wave detection equipment with a single-transmitter, dual-receiver transducer refers to a detection device that transmits sound waves through a single transmitting end and simultaneously uses two receiving ends to receive reflected or refracted sound wave signals.

[0056] Since the temporary cavities 6 and the rock damage zones 7 exist in the cut areas 8 on the stone face 4 after the first excavation cycle, it is sufficient to arrange only the outer cut holes, i.e., the first cut holes 1. Moreover, since the temporary cavities 6 provide additional free surfaces and expansion spaces for the blasting of the excavation cycle after the first excavation cycle, and the rock damage zones 7 with relatively low strength exist in the rock mass to be excavated, the charge amount of the first cut hole 1 on the stone face 4 after the first excavation cycle can be appropriately reduced and dynamically adjusted according to the geometric parameters of the rock damage zone 7, specifically according to the charge amount adjustment formula, and at least the charge amount of the first cut hole 1 among the first cut hole 1, the second cut hole 2, and the third cut hole 3 is adjusted according to the charge amount adjustment formula;

[0057] The formula for adjusting the charge amount is:

[0058] Wherein, η is the charge adjustment coefficient; η0 is the charge reference value, 0.4<η0<1.0, specifically 0.6<η0<0.8; R is the actual radius of the rock damage zone 7, R=3V / S, V is the volume of the rock damage zone 7, S is the surface area of the temporary cavity 6; R0 is the preset radius of the rock damage zone 7; α is the rock sensitivity coefficient, 0.5<α<1.5, specifically 0.7<α<1.3.

[0059] Based on the above formula and the rock damage zone 7 formed on the stone face 4 during the previous excavation cycle, the explosive charge of the first slot hole 1 in the next excavation cycle can be specifically adjusted, thereby reducing the amount of explosives while ensuring the quality of the slot cavity. Furthermore, because the stone faces 4 are parallel to each other in each excavation cycle in the present invention, the principal stress directions on the stone face 4 in different excavation cycles are not significantly different (within the allowable error range). Therefore, the magnitude and direction of the maximum principal stress and the magnitude and direction of the minimum principal stress on the stone face 4 only need to be determined before the first excavation cycle, and no further determination is required for subsequent excavation cycles. Alternatively, if working conditions require, the first slot hole 1 and / or the second slot hole 2 and / or the third slot hole 3 can be arranged in subsequent excavation cycles after the first excavation cycle, and the explosive charge of the first slot hole 1 in the next excavation cycle can be specifically adjusted based on the above formula and the rock damage zone 7 formed on the stone face 4 during the previous excavation cycle.

[0060] When the actual radius of the rock damage zone 7 in two consecutive excavation cycles is less than the preset radius of the rock damage zone 7, specifically when the deviation exceeds 20%, that is, when |R-R0| / R0>0.2, the blasting parameters of the slot hole group are adjusted. For example, the spacing between adjacent slot holes in the slot hole group is adjusted, such as increasing or decreasing it by 0.2m, and / or adjusting the number of slot holes in each slot hole layer, such as adding or removing one corresponding slot hole. Alternatively, other blasting parameters of the slot hole group can be adjusted accordingly based on the working conditions. This ensures rock breaking efficiency and slot cavity formation quality while strictly limiting the impact of geostress to the target area, reducing excessive disturbance of unnecessary rock mass, and thus reducing the problem of rock bursts or landslides caused by excessive disturbance of rock mass in unnecessary areas.

[0061] like Figure 6 、 Figure 7 As shown, at this time, η0 = 0.7, R0 = 0.9m, α = 1.0. After the first excavation cycle is completed, the actual radius of the rock damage zone 7 generated on the stone face 4 during the first excavation cycle is measured using an acoustic wave detector or other equipment, i.e., the equivalent radius R = 0.95m. The charge reduction coefficient η = 0.66 is calculated based on the charge adjustment formula. Except that the first slot hole 1, the second slot hole 2, and the third slot hole 3 are simultaneously arranged on the stone face 4 during the first excavation cycle, and only the first slot hole 1 is arranged on the stone face 4 during the second excavation cycle, the other blasting parameters of the slot hole group in the first and second excavation cycles are the same. Compared with the charge of the slot hole group in the first excavation cycle, the charge of the slot hole group in the second excavation cycle is reduced by 34%. Figures 2 to 7 As shown in the figure, area Ⅰ refers to the rock area involved in the first excavation cycle, area Ⅱ refers to the rock area involved in the second excavation cycle, similarly, areas Ⅲ and Ⅳ refer to the rock area involved in the third excavation cycle and the rock area involved in the fourth excavation cycle respectively; the distance between two adjacent cycle footage lines 5 in the figure is the cycle footage of the corresponding excavation cycle, for example, the cycle footage line 5 between the rock area Ⅰ and the rock area Ⅱ, and the distance between the cycle footage line 5 between the rock area Ⅱ and the rock area Ⅲ represent the cycle footage of the second excavation cycle.

[0062] Similar to the first excavation cycle, after the cut holes in the cut zone 8 are arranged in the second excavation cycle, caving holes and polished blasting holes are arranged in the caving zone 9 and polished blasting layer 10, respectively. All of these blasting holes are blasted sequentially from the inside out (from the inside out refers to the direction of excavation along the subgrade face 4). The rock mass produced by the blasting in the second excavation cycle is removed, and a temporary cavity 6 is formed on the subgrade face 4. The process of geometric parameter measurement → blasting parameter adjustment → blasting operation is then repeated until the tunnel is broken through and construction is completed.

[0063] Furthermore, the extension direction of the cut holes in step S1 and step S4 of the present invention is inclined to the stone surface 4, that is, the cut holes in the present invention are oblique cut holes. Since the blast holes of the oblique cut holes are inclined to the stone surface 4, the explosive energy in the oblique cut holes is concentratedly released along the inclined direction, which makes the explosive energy direction of the oblique cut holes easier to couple with the bedding and joint directions of the rock mass (bedding is a layered structure produced by the change of the rock mass along the vertical direction, and joints refer to cracks produced by the stress on the rock mass), inducing the expansion of cracks on the rock mass and reducing the amount of explosives used; the oblique cut holes can specifically be one-way cut holes, tapered cut holes, wedge-shaped cut holes or fan-shaped cut holes; or, if the working conditions require, other types of cut holes such as straight cut holes (the extension direction of the cut holes is perpendicular to the stone surface 4) can also be used.

[0064] like Figures 2 to 6 As shown, when the slot holes are cut with oblique eyes, in step S1 and step S4, all the slot holes on the stone surface 4 are wedge-shaped and symmetrically distributed along the maximum principal stress direction of the stone surface 4 as the symmetry axis, which enables the first slot hole 1 to produce a larger slot cavity, facilitates the formation of the subsequent rock damage zone 7, and then promotes the quality of blasting in the subsequent excavation cycle; specifically, the aperture of the slot hole can be 42 mm, and coupled charges can be used. The charge length can be 40% of the slot hole length, and the slot hole blocking length can be 20% of the slot hole length.

[0065] This invention is suitable for full-section blasting excavation of deep tunnels under high geostress conditions. Full-section blasting excavation means that the entire section can reach the designed excavation depth and cross-sectional dimensions with a single blast. This invention fully utilizes the auxiliary effect of the geostress field on rock breaking, improving the excavation efficiency during millisecond-delay blasting of deep, high-geostress tunnels, and has broad application prospects.

[0066] In this article, and / or refers to the text content located in front of and / or, and the text content located in the back of and / or can exist at the same time or separately; for example, A and / or B includes the situation where only A or B exists, and the situation where A and B exist at the same time.

[0067] The present invention discloses multiple technical solutions, but does not provide any contrary technical inspiration.

[0068] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A slot blasting method, characterized in that: The slot blasting method comprises the following steps: Step S1, arranging the cut hole group required for the current excavation cycle on the stone surface; The excavation cycle includes drilling, charging, blasting and slagging on the subgrade surface; the slot hole group includes a plurality of first slot holes, and the first slot holes extend from the rock mass area involved in the current excavation cycle to the rock mass area involved in the next excavation cycle; Step S2, detonating the cut hole group required for the current excavation cycle; Step S3, determining the geometric parameters of the rock mass damage zone formed on the subgrade surface during the previous excavation cycle; Wherein, the geometric parameters include the position of the rock mass damage zone and the volume of the rock mass damage zone; Step S4, arranging the slot hole group required for the next excavation cycle on the stone surface, and adjusting the blasting parameters of the slot hole group required for the next excavation cycle according to the geometric parameters; The blasting parameters include the number of the first slot holes in the slot hole group, and / or the spacing between adjacent first slot holes, and / or the charge amount of the first slot holes; Step S5, looping through steps S2 to S4 until the construction is completed.

2. The slot blasting method according to claim 1, characterized in that: The depth of the first trench hole is the sum of the cycle footage of the current excavation cycle and the cycle footage of the next excavation cycle.

3. The slot blasting method according to claim 1, characterized in that: The slot hole group also includes a plurality of second slot holes, which are arranged in sequence with the first slot holes along the excavation direction of the subgrade face, and the depth of the second slot holes is the cycle feed of the current excavation cycle.

4. The slot blasting method according to claim 3, characterized in that: When the distance between the first notch hole and the second notch hole is greater than a preset value, the notch hole group further includes a third notch hole located between the first notch hole and the second notch hole, and the depth of the third notch hole is greater than the depth of the second notch hole and less than the depth of the first notch hole.

5. The slot blasting method according to claim 4, characterized in that: Adjusting the blasting parameters required for the next excavation cycle in step S4 includes: adjusting the charge of at least the first slot hole, the second slot hole, and the first slot hole among the third slot holes according to a charge adjustment formula; The charge adjustment formula is: Where η is the charge adjustment coefficient; η0 is the charge reference value, 0.4<η0<1.0; R is the actual radius of the rock damage zone; R0 is the preset radius of the rock damage zone; α is the rock sensitivity coefficient, 0.5<α<1.

5.

6. The slot blasting method according to any one of claims 1 to 5, characterized in that: When the actual radius of the rock damage zone in two consecutive excavation cycles is smaller than the preset radius of the rock damage zone, the blasting parameters of the cut hole group required for the next excavation cycle are adjusted.

7. The slot blasting method according to any one of claims 1 to 5, characterized in that: The extending direction of the groove hole group in the step S1 and the step S4 is inclined to the stone surface.

8. The slot blasting method according to claim 7, characterized in that: In the step S1 and the step S4, all the first cutout holes on the stone surface are wedge-shaped and symmetrically distributed with the maximum principal stress direction of the stone surface as the symmetry axis.

9. The slot blasting method according to any one of claims 1 to 5, characterized in that: The cutout hole groups are arranged along the direction of maximum principal stress of the substructure surface.

10. The slot blasting method according to claim 9, characterized in that: The slot blasting method includes: before arranging the slot hole group in step S1, using a stress relief method, a hydraulic fracturing method or an acoustic emission method to determine the maximum principal stress direction on the subsurface.

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