A hole bottom buffering and energy dissipation method for underwater blasting

Abstract

The present invention discloses a hole bottom buffering and energy dissipation method for underwater blasting, which mainly includes: 1) drilling a blasthole on a rock foundation to be excavated; 2) placing a loose sand layer at the bottom of the blasthole; 3) placing an energy dissipation seat on the loose sand layer; 4) loading water-resistant explosives into the blasthole, and detonating after blocking. In the present invention, the energy dissipation seat is composed of a conical part and a cylindrical part, the conical part is made of a high wave impedance material, and the cylindrical part is made of an energy absorbing material. The present invention uses hollow glass micro-bead concrete to reduce the vertical shock wave at the bottom of the blasthole, which provides a new idea for reducing the damage to the bedrock at the bottom of the hole in the construction of water-containing blasthole blasting.

Description

Technical Field

[0001] The invention relates to the technical field of engineering blasting, and in particular to a hole bottom buffering and energy dissipation method for underwater blasting. Background Art

[0002] The excavation of dam foundations, steep slopes and underground chambers of water conservancy and hydropower projects is a key difficulty in the construction of water conservancy and hydropower projects. The quality of construction is directly related to the safety of the construction period and operation period of water conservancy and hydropower projects. Traditional drilling and blasting technology is often difficult to control the construction quality and has low efficiency. In recent years, the energy dissipation-energy gathering combined controlled blasting technology is a construction method with the highest comprehensive efficiency and significantly reduced blasting costs.

[0003] However, in actual projects, the rock mass contains certain joints and cracks, which makes the blastholes filled with water during construction. The energy dissipation-energy gathering combined controlled blasting technology uses loose sand as a buffer layer at the bottom. The loose sand is saturated with water and is easily liquefied under the action of blasting vibration, making it difficult to play the role of a buffer layer. How to improve the energy dissipation-energy gathering combined controlled blasting technology in a water-rich environment is a problem that needs to be solved at present. Summary of the invention

[0004] In view of the above problems, a hole bottom buffering and energy dissipation method for underwater blasting is provided, which can be used for drilling and blasting construction in water-rich environment.

[0005] The specific technical solutions are as follows:

[0006] A hole bottom buffering and energy dissipation method for underwater blasting has the following characteristics and comprises the following steps:

[0007] 1) Drilling blastholes on the rock foundation to be excavated;

[0008] 2) Put loose sand at the bottom of the blasthole so that the thickness of the loose sand layer is less than the depth of water accumulation in the blasthole;

[0009] 3) Place the energy dissipation seat on the loose sand;

[0010] 4) Load water-resistant explosives into the blasthole, block the blasthole and then detonate;

[0011] Among them, the energy dissipation seat is formed by pouring concrete mixed with hollow glass microspheres.

[0012] The above-mentioned hole bottom buffering and energy dissipation method for underwater blasting also has the characteristic that when the rock foundation is soft rock, the energy dissipation seat is spherical.

[0013] The above-mentioned hole bottom buffering and energy dissipation method for underwater blasting also has the characteristic that when the rock foundation is medium-hard rock, the energy dissipation seat is in the shape of a short column.

[0014] The above-mentioned hole bottom buffering and energy dissipation method for underwater blasting also has the characteristic that when the rock foundation is hard rock or super-hard rock, the energy dissipation seat is in a cone shape.

[0015] The above-mentioned hole bottom buffering and energy dissipation method for underwater blasting also has the following characteristics: when the rock foundation is hard rock or superhard rock, the energy dissipation seat includes a cylindrical part and a conical part installed on the cylindrical part, the conical part is formed by casting iron sand concrete, and the cylindrical part is formed by casting concrete doped with hollow glass microspheres.

[0016] The above-mentioned hole bottom buffering and energy dissipation method for underwater blasting also has the following characteristics: the cylindrical part and the conical part are of the same height, the diameter of the conical bottom surface of the conical part is equal to the diameter of the cylindrical part, and the angle between the generatrix of the conical part and the conical bottom surface is 45°.

[0017] The above-mentioned hole bottom buffering and energy dissipation method for underwater blasting also has the characteristic that the ratio of the diameter of the cylindrical part to the diameter of the blasthole is 0.7-0.9.

[0018] The above-mentioned hole bottom buffering and energy dissipation method for underwater blasting also has the characteristic that the thickness of the loose sand layer is 20-30 cm.

[0019] The beneficial effects of the above scheme are:

[0020] In the present invention, due to the crushing of the energy dissipation seat, the buffering of the loose sand layer at the bottom of the hole and the multiple reflections and transmissions of the stress wave in the conical and cylindrical energy dissipation seat structures, the explosion shock wave transmitted in the vertical direction of the blasthole in a water-rich environment will be further reduced, thereby reducing the damage to the bedrock at the bottom of the hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the arrangement of blastholes in the present invention;

[0022] Figure 2 It is a schematic diagram of a single blast hole structure in the present invention;

[0023] Figure 3 It is a structural schematic diagram of the energy dissipation seat in the present invention;

[0024] Figure 4 Schematic diagram of the propagation of shock waves in the blast hole of the present invention.

[0025] In the attached figure: 1. free water surface; 2. blocking layer; 3. explosive cartridge; 4. energy dissipation seat; 5. loose sand layer; 6. rock foundation; 7. vertical shock wave; 8. hollow glass microspheres; 9. reflected wave. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0027] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0029] Example 1

[0030] A hole bottom buffering and energy dissipation method for underwater blasting, comprising the following steps:

[0031] 1) Drilling blastholes: see Figure 1 , the positions and dimensions of vertical blastholes are arranged on the hard rock or super-hard rock foundation 6 to be excavated, with a blasthole diameter of 100 mm, a blasthole depth of 9 m, a plugging length of 2 m, and a blasthole spacing of 3 m;

[0032] 2) Blast hole measurement:

[0033] Tie a long metal block smaller than the diameter of the blasthole to one end of the handheld measuring rope, put the handheld measuring rope into the blasthole, and measure the hole depth and water depth in the hole to ensure that the blasthole depth meets the design requirements and the water depth is greater than the thickness of the loose sand buffer layer at the bottom of the hole. If the above requirements are not met, it is necessary to add blastholes according to the design plan;

[0034] 3) Laying the buffer layer:

[0035] A loose sand layer 5 with a thickness of 30 cm is evenly laid at the bottom of the blasthole that meets the requirements.

[0036] 4) Place the energy dissipation seat:

[0037] like Figure 3 As shown, in this embodiment, the energy dissipation seat 4 includes a cylindrical portion and a conical portion installed on the cylindrical portion and at the same height as the cylindrical portion. The diameter of the conical bottom surface of the conical portion is 80 mm, the height of the conical portion is 40 mm, and the angle between the generatrix of the conical portion and the conical bottom surface is 45°. When placing, the energy dissipation seat 4 is fastened with a nylon rope and slowly pulled onto the loose sand layer 5;

[0038] 5) Charging and detonation:

[0039] An emulsion explosive roll 3 with a diameter of 80 mm and a length of 6.5 m is loaded into the blasthole. Considering that there is water in the blasthole, traditional gun mud is first used for blocking, and then gravel with a diameter of 5-10 mm is used for filling. After the blocking layer 2 is completed and confirmed to be safe, a detonator is used to detonate the explosive in the blasthole. Figure 4 As shown, after the explosive explodes, when the vertical shock wave 7 in the blasthole is transmitted to the energy dissipation seat 4, affected by the shape of the conical structure on the energy dissipation seat 4 and the small amount of hollow glass beads 8 contained in the conical part, part of the vertical shock wave 7 is reflected. At the same time, since the angle between the generatrix of the cone and the bottom of the cone is 45°, the horizontal shock wave formed will be beneficial to the destruction of the hard rock of the blasthole wall. Since the cylindrical part and the upper conical structure have the same diameter, most of the transmission wave in the upper conical structure will be transmitted to the lower cylindrical part. Since the amount of hollow glass beads added in the cylindrical part is larger and its wave impedance is smaller, the transmission wave will meet the hollow glass beads again to generate the reflection wave 9, and almost no transmission wave reaches the bottom of the hole, thereby reducing the vertical shock wave intensity inside the blasthole, and then reducing the damage of the shock wave to the bedrock. In the above process, due to the crushing of the energy dissipation seat 4, the buffering of the loose sand layer 5 at the bottom of the hole, and the multiple reflections and transmissions of the stress wave in different wave impedance materials, the explosion shock wave transmitted in the vertical direction of the blast hole in the water-rich environment will be further reduced, thereby reducing the damage to the bedrock at the bottom of the hole.

[0040] The casting method of the energy dissipation seat 4 in this embodiment is as follows: the steel mold is placed upside down on the bracket, and the conical part iron sand-hollow glass microsphere concrete is cast first (the content of hollow glass microspheres in the iron sand-hollow glass microsphere concrete is 1%), and the cylindrical part hollow glass microsphere concrete is cast at its bottom before it is initially set. After the casting and vibration are completed, the plastic wrap is pasted, and the mold is removed after 24 hours for standard curing, and it is taken out after 28 days.

[0041] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A hole bottom buffering and energy dissipation method for underwater blasting, characterized in that: The steps include: 1) Drilling blastholes on the rock foundation to be excavated; 2) Put loose sand at the bottom of the blasthole so that the thickness of the loose sand layer is less than the depth of water accumulation in the blasthole; 3) Place the energy dissipation seat on the loose sand layer; 4) Load water-resistant explosives into the blasthole, block the blasthole and then detonate; Among them, when the rock foundation is hard rock or superhard rock, the energy dissipation seat includes a cylindrical part and a conical part installed on the cylindrical part, the conical part is formed by pouring concrete doped with iron sand and hollow glass microspheres, and the cylindrical part is formed by pouring concrete doped with hollow glass microspheres.

2. The hole bottom buffering and energy dissipation method for underwater blasting according to claim 1, characterized in that: The cylindrical portion and the conical portion are of the same height, and the diameter of the conical bottom surface of the conical portion is equal to the diameter of the cylindrical portion, and the included angle between the generatrix of the conical portion and the conical bottom surface is 45°.

3. The hole bottom buffering and energy dissipation method for underwater blasting according to claim 2, characterized in that: The ratio of the diameter of the cylindrical portion to the diameter of the blasthole is 0.7-0.

9.

4. The hole bottom buffering and energy dissipation method for underwater blasting according to any one of claims 1 to 3, characterized in that: The thickness of the loose sand layer is 20-30 cm.

Images