Rock plug blasting method

Abstract

The invention discloses a rock plug blasting method, and belongs to the field of water conservancy and hydropower engineering. The method comprises the steps that the sizes of an internal rock plug and an external rock plug are determined according to the geological condition of a water inlet and the design flow, contour holes are formed in the contour line of the internal rock plug and the contour line of the external rock plug according to the design scheme, and a block cutting hole is formed between the internal rock plug and the external rock plug; and determining the charging structure according to the geological condition of the water inlet, the drilling condition of the blast hole and the performance of the blasting material. During construction, the inner rock plug contour hole is firstly detonated to form the inner rock plug, then the center hole I sequence explosive is detonated to crush the inner rock plug body, then the outer rock plug contour hole is detonated to form the outer rock plug, finally, the block cutting hole and the center hole II sequence explosive are detonated, the outer rock plug rock is crushed, and the inner rock plug is pushed into the slag collecting pit. And after detonation, the external rock plug gravel and the internal rock plug gravel fall into the slag collecting pit under the combined action of the explosion load and the water load. The method can effectively reduce the number of drilled holes and the use amount of explosives, the cost is lower, and the construction precision is higher.

Description

Technical Field

[0001] The invention relates to water conservancy projects, and in particular to a water inlet rock plug blasting construction method. Background Art

[0002] There are usually three construction methods for the construction of water inlets for diversion or discharge tunnels in existing reservoirs or natural lakes. First, temporary cofferdams are used to block water. Second, the reservoir is emptied or the water level is lowered. Third, reserved rock plugs are used to temporarily block water. Finally, rock plug blasting is used for construction. Since these water inlets are located tens of meters below the water surface, emptying or lowering the water level of the reservoir will have a great negative impact and loss on society, economy, environment, ecology and tourism. If a deep water cofferdam is built, the construction is relatively complex and difficult, the construction period is long, and the cofferdam is difficult to dismantle after the water inlet is built. The project cost is high. Some projects are restricted by factors such as topography, geology, and water depth. There is no possibility of building a cofferdam at all. It is impossible to empty the reservoir or lower the water level. Rock plug blasting becomes the only option.

[0003] Limited by blasting equipment and construction equipment, underwater rock plug blasting in the past mostly used chamber blasting methods, which later gradually developed into using concentrated explosive packs in the middle of the rock plug and drilling blasting in the surrounding expansion part. Due to the large vibration impact of chamber blasting and high uncertainty factors, most projects now do not allow or abandon the use of chamber blasting. In contrast, full-row hole blasting has its unique advantages. Under the premise of gradually improving the accuracy of detonator delay and significantly improving the quality of drilling construction, it can effectively control the amount of single-shot charge, reduce the impact of blasting on the retained rock mass and nearby buildings, and significantly improve safety. Whether it is chamber blasting or full-row hole blasting, the rock at the rock plug is broken into smaller blocks and then discharged into the river or slag pit. The unit consumption of explosives is large, the cost is high, and the impact on the surrounding rock mass is large.

[0004] In summary, the current water intake rock plug blasting construction method still needs further improvement. Summary of the invention

[0005] In order to solve the problems existing in the current rock plug blasting construction method, the patent of the present invention provides a rock plug blasting method, which utilizes the new full-row hole blasting technology to blast and remove the water inlet rock plug, thereby weakening the impact of traditional full-row hole blasting on the surrounding surrounding rock, reducing the consumption of explosives and the difficulty of construction, and reducing the construction cost.

[0006] The technical solution adopted by the present invention is: A rock plug blasting method, the specific steps are: (1) Determining the sizes of the internal rock plug and the external rock plug according to the design flow rate of the water inlet and the geological conditions of the water inlet, wherein the internal rock plug is arranged at the bottom center of the rock plug; (2) According to the design dimensions, contour holes are drilled on the inner rock plug contour line and the outer rock plug contour line, so that the length of the inner rock plug is shorter than the length of the outer rock plug; (3) Drilling a block cutting hole between the inner rock plug and the outer rock plug contour hole; (4) Setting a center hole in the rock plug; (5) Determine the charge structure based on the geological conditions of the water inlet, the drilling conditions of the blastholes, and the performance of the blasting equipment; (6) Detonate according to the detonation network.

[0007] During construction, the inner rock plug contour hole is first detonated to shape the inner rock plug, then the center hole explosive in the inner rock plug is detonated to break the inner rock plug body, then the outer rock plug contour hole is detonated to shape the outer rock plug, and finally the block cutting hole and the center hole explosive in the outer rock plug are detonated to crush the outer rock plug rock and push the inner rock plug into the slag collection pit. After detonation, the outer rock plug crushed stone and the inner rock plug crushed stone fall into the slag collection pit under the combined action of the explosion load and the water load. The present invention effectively reduces the number of holes drilled and the amount of explosives used, has lower costs, higher construction accuracy, and weakens the impact of traditional full-row hole blasting on the surrounding surrounding rock.

[0008] More specifically, in the rock plug described in step (1), the rock plug is cylindrical or truncated cone-shaped as a whole, and the internal rock plug is a truncated cone-shaped with the upstream side as the top surface and the downstream side as the bottom surface, wherein the minimum radius of the external rock plug is determined by calculation formula (1):

[0009] Where: Q max is the maximum design flow rate of the tunnel; [v] is the allowable anti-impact flow velocity of the surrounding rock at the rock plug mouth; the thickness-to-diameter ratio of the rock plug is determined according to the geological conditions.

[0010] More specifically, the external rock plug is cylindrical, and the internal rock plug is a right truncated cone with the upstream side as the top surface and the downstream side as the bottom surface; the external rock plug contour hole is parallel to the rock plug axis, and the internal rock plug contour hole is an internal shrinkage hole with a certain angle with the rock plug axis; a block cutting hole parallel to the rock plug axis is provided between the internal rock plug and the external rock plug; the center hole and the block cutting hole both penetrate the internal rock plug and extend to the external rock plug.

[0011] More specifically, in the rock plug blasting method described in step (1), the rock plug blasting construction area is divided into three areas according to the action range of the blastholes, wherein the rock mass in area I is crushed by the blasting action of the internal rock plug contour holes and the center hole, the rock mass in area II is crushed by the action of the external rock plug contour holes, and the rock mass in area III is crushed by the action of the external rock plug contour holes, the block cutting holes and the center hole.

[0012] More specifically, in the internal and external rock plugs described in step (1), the rock plugs are arranged in an upward tilted manner, and the angle between their axis and the horizontal plane is preferably 30° to 60°. During construction, it is determined according to the rock plug design and the geological conditions of the construction site, and a larger value is preferably taken.

[0013] More specifically, in the contour hole described in step (2), the outer rock plug contour hole is parallel to the rock plug axis, and the inner rock plug contour hole is an inner shrinkage hole with a certain angle with the axis, and the inner shrinkage angle is 5°~15°; the length of the inner rock plug (the distance from the top surface to the bottom surface of the inner rock plug) is 1 / 2~2 / 3 of the length of the outer rock plug; the bottom radius R1 of the inner rock plug is 60%~80% of the radius R of the outer rock plug; the circumferential radius of the block cutting hole is not greater than (R2+R) / 2. Preferably, the block cutting hole is arranged on a circle with a radius of (R2+R) / 2, wherein R2 is the top radius of the inner rock plug.

[0014] More specifically, in the contour hole of step (2), pre-splitting blasting is adopted, the hole diameter is between 50mm-90mm, the hole spacing of the contour hole is between 0.5m-1m, discontinuous uncoupled charge is adopted in the contour hole, and the blasthole blocking length should not be less than the minimum resistance line (the minimum distance between the bottom of the contour hole and the water surface), and should not be less than 0.5m.

[0015] Furthermore, the depths of the contour holes of the inner rock plug contour line are arranged in alternating long and short configurations; and the depths of the contour holes of the outer rock plug contour line are consistent.

[0016] More specifically, in the block cutting hole arrangement method described in step (3), the block cutting hole is drilled between the outer rock plug and the inner rock plug along the axial direction.

[0017] More specifically, in the block cutting hole drilling method described in step (3), the block cutting hole has a hole diameter between 50 mm and 100 mm, a hole opening spacing between 1 m and 2 m, and the block cutting hole uses continuous coupled charge.

[0018] More specifically, in the charge structure described in step (4), only part of the charge located in the outer rock plug area is contained in the block cutting hole.

[0019] More specifically, in the center hole described in step (4), the diameter and depth of the center hole are consistent with those of the block cutting hole, and the distance between the bottom of the block cutting hole and the bottom of the center hole and the free surface (water surface) is about 0.5~1m, which is determined according to the geological conditions. In step (5), the center hole is charged in two sections, the first section is charged in the middle, and the charging position is located within zone I (internal rock plug area), and the second section is charged at the bottom of the hole and does not exceed zone III (external rock plug area).

[0020] More specifically, in the rock plug blasting method in steps (1) to (6), when the rock plug is detonated, the detonation sequence is inner rock plug contour hole - center hole sequence I - outer rock plug contour hole - block cut hole - center hole sequence II; the center hole sequence I refers to the portion of the center hole in the inner rock plug; the center hole sequence II refers to the portion of the center hole extending to the outer rock plug.

[0021] More specifically, in the rock plug blasting method in steps (1) to (6), the internal rock plug is formed by contour blasting, the rock at the bottom of the internal rock plug is crushed by row hole blasting, and the blasting load and water load are used to throw the blasting slag into the slag collection pit.

[0022] More specifically, in the rock plug blasting method in steps (1) to (6), the external rock plug is formed under the action of contour blasting, and the block cutting hole is detonated after the contour hole is detonated, and the external rock plug body is broken under the action of blasting and falls into the slag collection pit.

[0023] Compared with the existing rock plug blasting method, the technical solution of the present invention has the following advantages: 1) Only three rows of blast holes (two rows of contour holes and one row of block cutting holes) and one center hole are arranged, the drilling difficulty is lower, the blasting network is relatively simple, and the cost is low; 2) The blasting load is used to crush part of the rock mass and the blasting load and water load are used to throw the blasting slag into the slag collection pit. Traditional full-row hole rock plug blasting usually uses the form of slot blasting, in which center holes, slot holes, collapse holes and peripheral contour holes are arranged in the rock plug body, and multiple layers of collapse holes are often arranged in the radial direction of the rock plug to break the rock plug body into smaller pieces and throw them into the slag collection pit. The traditional full-row hole underwater rock plug blasting has a complex detonation network and a large number of drill holes. In contrast, this method does not pursue the complete crushing of the rock plug, reduces the use of explosives, reduces the number of drill holes, has a simple detonation network, and has less impact on the surrounding rock mass. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a cross-sectional schematic diagram of the construction method of the present invention.

[0025] Figure 2 It is a schematic longitudinal section diagram of the construction method of the present invention.

[0026] Figure 3It is a schematic diagram of the overall layout of the construction method of the present invention.

[0027] In the figure: 1-external rock plug contour hole, 2-external rock plug contour line, 3-internal rock plug contour hole (long), 4-internal rock plug contour hole (short), 5-internal rock plug contour line, 6-block cutting hole, 7-center hole, 8-surrounding rock. DETAILED DESCRIPTION

[0028] In order to have a more intuitive understanding of the technical solution of the invention, the technical solution of the invention is further elaborated and illustrated in combination with the accompanying drawings and specific implementation methods.

[0029] like Figure 1-3 As shown, an internal rock plug is arranged at the bottom center of the rock plug to form an internal rock plug and an external rock plug; the external rock plug is cylindrical, and the internal rock plug is a right truncated cone with the upstream side as the top surface (close to the water surface direction) and the downstream side as the bottom surface; the length of the internal rock plug (the distance from the top surface to the bottom surface of the internal rock plug) is smaller than the length of the external rock plug; the external rock plug contour hole 1 is parallel to the axis of the rock plug, and the internal rock plug contour hole is an inner shrinkage hole with a certain angle with the axis of the rock plug; a block cutting hole 6 parallel to the axis of the rock plug is arranged between the internal rock plug and the external rock plug; the center hole 7 and the block cutting hole 6 both penetrate the internal rock plug and extend to the external rock plug.

[0030] Contour holes are drilled on the inner rock plug contour line 5 and the outer rock plug contour line 2, namely the inner rock plug contour hole 3 / 4 and the outer rock plug contour hole 1. Discontinuous uncoupled charge is used in the contour holes; the center hole 7 is charged in two sections, the first section is charged in the middle, the charging position is located in the inner rock plug area, and the second section is charged at the bottom of the hole and does not exceed the outer rock plug area; the block cutting hole 6 is only charged in the part inside the outer rock plug, and continuous coupled charge is used.

[0031] In some examples, 3 / 4 of the inner rock plug contour hole is an inner shrinkage hole that forms an angle of 5°~15° with the axis of the rock plug; the length of the inner rock plug is 1 / 2~2 / 3 of the length of the outer rock plug; the bottom radius R1 of the inner rock plug is 60%~80% of the radius R of the outer rock plug; the circumferential radius of the block cutting hole 6 is not greater than (R2+R) / 2, where R2 is the top radius of the inner rock plug.

[0032] In the rock plug blasting construction area, it is divided into three areas according to the action range of the blastholes. The rock mass in zone I is broken by the blasting action of the internal rock plug contour hole and the center hole 7, the rock mass in zone II is broken by the action of the external rock plug contour hole 1, and the rock mass in zone III is broken by the action of the external rock plug contour hole 1, the block cutting hole 6 and the center hole 7.

[0033] In some examples, the rock plug is arranged in an upward tilted manner, with the angle between the axis of the rock plug and the horizontal plane being 30°~60°.

[0034] In some examples, the inner rock plug contour line 5 and the outer rock plug contour line 2 are blasted by contour blasting, the contour hole diameter is between 50mm-90mm, and the hole spacing of the contour holes is between 0.5m-1m; the block cutting hole 6 has a diameter between 50mm-100mm, and the hole spacing is between 1m-2m.

[0035] The technical solution of the present invention will be described clearly and completely in combination with examples. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative labor are within the scope of protection of the present invention. The bottom of the hole is determined by the drilling direction.

[0036] like Figure 1 As shown, the maximum discharge flow of a flood discharge tunnel of a certain project is 332m 3 / s, rock anti-impact flow velocity is 15m / s, and the technical solution of the present invention is used for construction, and the specific steps are as follows: (1) Based on the design flow rate and the allowable anti-impact flow velocity of the rock, the minimum diameter of the water inlet is:

[0037] The outer rock plug is selected to be cylindrical with a radius of 3m. The thickness-diameter ratio of the rock plug is about 1.1, the average thickness of the rock plug is about 6.5m, and the center thickness is 6.0m. The inner rock plug is a right truncated cone, with a bottom radius of 2.5m and a top radius of 1.7m. The block cutting hole 6 is arranged on a circle with a radius of 2.35m and the center of the rock plug as the center. (1) The rock plug in this example is located nearly 30m underwater. The surface of the rock plug is covered with 2-12m of accumulated soil. The rock type is limestone with dissolution gaps and dissolution pores. The rock mass integrity is poor. Therefore, the angle between the axis of the rock plug and the horizontal line in this example is 30°. (2) According to the designed rock plug size, an external rock plug contour hole 1 is arranged on a circular contour with a radius of 3 m, with the center of the bottom of the rock plug as the center of the circle. In the example of the present invention, the external rock plug contour hole 1 has an inner shrinkage angle of 0°, a hole diameter of 90 mm, a hole length of 5.0-5.5 m, a distance between two adjacent blastholes of 0.47, and a bottom resistance line length of 1.0 m; (3) According to the size of the rock plug, the inner rock plug contour holes are arranged on a circular contour with a radius of 2.35 m, with the center of the bottom of the rock plug as the center of the circle. The inner rock plug contour holes are arranged alternately in long and short shapes. In the example of the present invention, the 3 / 4 inner reduction angle of the inner rock plug contour hole (long / short) is 15°, the hole diameter is 90 mm, the hole length of the inner rock plug contour hole (long / short) is 3.1 m / 1.55 ​​m, and the distance between the openings of two adjacent blastholes (openings of contour holes) is 0.6 m; (4) According to the designed outline of the block cutting hole 6, the block cutting hole 6 is arranged on a circle with a radius of 2.35m, with the center of the bottom of the rock plug as the center of the circle. In the example of the present invention, the block cutting hole 6 has an inner shrinkage angle of 0°, a hole diameter of 60mm, a hole length of 5.0-5.5m, a blasthole is arranged every 90°, and a total of four blastholes are arranged. The length of the hole bottom resistance line (the distance between the hole bottom and the water surface) is 0.5-1.0m; (5) According to the designed rock plug size, a center hole 7 is set at the center of the rock plug. The center hole 7 has an inner shrinkage angle of 0°, a hole diameter of 90 mm, a hole length of 5.0 m, and a bottom resistance line (the distance between the bottom of the hole and the water surface) of 1.0 m. (6) In the present invention, the inner and outer contour holes use uncoupled interval charging, the block cutting hole 6 uses continuous coupled charging, the contour hole line charging density is 1000g / m, the hole bottom charging amount is doubled, the block cutting hole 6 charging length is 1m, and the line charging density is 3330g / m; (7) In this example, the rock mass in zone I is broken by the blasting action of the inner rock plug contour hole and the center hole 7, the rock mass in zone II is broken by the blasting action of the outer rock plug contour hole 1, and the rock mass in zone III is broken by the blasting action of the outer rock plug contour hole 1, the block cutting hole 6, and the center hole 7. (8) After the number and location of blastholes are set, drilling equipment is used to drill holes and excavate pilot tunnels and chambers. After the blastholes and chambers are checked and found to be correct, explosives are loaded and the detonation network is set. The blasting is carried out using millisecond differential blasting and staged detonation. The detonation sequence is inner rock plug contour hole-center hole I sequence-external rock plug contour hole-block cutting hole-center hole II sequence; (9) The contour holes, block cut holes and center holes are charged according to the blasting parameters and the blasting network is set up, and then the explosives in the peripheral holes and the chamber are detonated in sequence. After the blasting is completed, the blasting effect is checked.

[0038] It has been verified by practice that the present invention only arranges three rows of blast holes (two rows of contour holes and one row of block cutting holes) and one central hole, adopts contour blasting to shape the water inlet rock plug, utilizes row hole blasting to destroy the rock, and utilizes blasting load and water load to throw the blasting slag into the slag collection pit. Compared with the traditional blasting method, this method does not seek to crush all the rock plugs, reduces the number of drilling holes and the amount of explosives used, has less impact on the surrounding rock mass, has lower cost, and has higher construction accuracy.

[0039] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention are within the scope of the technical solution of the present invention. The above specific implementation methods describe the implementation of the present invention in detail, but the present invention is not limited to the specific details in the above implementation methods. Within the scope of the claims and technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications and changes, and these simple variations are within the scope of protection of the present invention.

Claims

1. A rock plug blasting method, characterized in that: The following steps are involved: Determine the size of the inner rock plug and the outer rock plug according to the design flow of the water inlet and the geological conditions of the water inlet, wherein the inner rock plug is arranged at the bottom center of the rock plug; According to the design dimensions, contour holes are set on the inner rock plug contour line and the outer rock plug contour line respectively, so that the length of the inner rock plug is smaller than that of the outer rock plug; a block cutting hole is set between the inner rock plug and the outer rock plug; and a center hole is set at the center of the rock plug; Determine the charge structure according to the geological conditions of the water inlet, the drilling conditions of the blastholes and the performance of the blasting equipment; Detonate according to the detonation network.

2. A rock plug blasting method according to claim 1, characterized in that: The external rock plug is cylindrical, and the internal rock plug is a right truncated cone with the upstream side as the top surface and the downstream side as the bottom surface; a block cutting hole parallel to the axis of the rock plug is arranged between the internal rock plug and the external rock plug; the center hole and the block cutting hole both penetrate the internal rock plug and extend to the external rock plug.

3. A rock plug blasting method according to claim 2, characterized in that: The contour hole adopts discontinuous uncoupled charging; the center hole is divided into two sections for charging, the first section is charged in the middle, the charging position is located in the internal rock plug area, and the second section is charged at the bottom of the hole and does not exceed the external rock plug area; the block cutting hole is only charged in the part inside the external rock plug, and continuous coupled charging is adopted.

4. A rock plug blasting method according to claim 2, characterized in that: The internal rock plug contour hole is an internal shrinkage hole that forms an angle of 5°~15° with the axis of the rock plug; the length of the internal rock plug is 1 / 2~2 / 3 of the length of the external rock plug; the bottom radius R1 of the internal rock plug is 60%~80% of the radius R of the external rock plug; the circumferential radius of the block cutting hole is not greater than (R2+R) / 2, where R2 is the top radius of the internal rock plug.

5. A rock plug blasting method according to claim 1, characterized in that: In the rock plug blasting construction area, it is divided into three areas according to the action range of the blastholes, wherein the rock mass in area I is broken by the blasting action of the internal rock plug contour holes and the center hole, the rock mass in area II is broken by the action of the external rock plug contour holes, and the rock mass in area III is broken by the action of the external rock plug contour holes, the block cutting holes and the center hole.

6. A rock plug blasting method according to claim 1, characterized in that: The rock plug is arranged in an upward tilted manner, with the angle between the axis of the rock plug and the horizontal plane being 30°~60°.

7. A rock plug blasting method according to claim 1, characterized in that: The inner rock plug contour line and the outer rock plug contour line are made by contour blasting, the diameter of the contour hole is between 50mm-90mm, and the distance between the hole openings is between 0.5m-1m; the diameter of the block cutting hole is between 50mm-100mm, and the distance between the hole openings is between 1m-2m.

8. A rock plug blasting method according to claim 1, characterized in that: The diameter and depth of the central hole are consistent with those of the block cutting hole.

9. A rock plug blasting method according to claim 1, characterized in that: The depths of the contour holes of the internal rock plug contour line are arranged in alternating long and short configurations.

10. A rock plug blasting method according to claim 1, characterized in that: During detonation, the detonation sequence is inner rock plug contour hole - center hole sequence I - outer rock plug contour hole - block cutting hole - center hole sequence II.

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