Cavity preset type slotting hole charging structure

Abstract

The utility model discloses a cavity preset type slotting hole charging structure which comprises a slotting shot hole, the slotting shot hole is composed of a main blasting section penetrating through a current circulation drilling footage rock mass and an extension charging section extending into a next circulation drilling footage rock mass, and the extension charging section is composed of a front charging section and a rear charging section; the main explosive section, the front explosive loading section and the rear explosive loading section are filled with explosives respectively, the explosives in all the sections are connected through detonating cords, and the relation between the explosive detonation velocity of the front explosive loading section, the explosive detonation velocity of the main explosive loading section and the explosive detonation velocity of the rear explosive loading section is that the explosive detonation velocity of the front explosive loading section is larger than the explosive detonation velocity of the rear explosive loading section. According to the utility model, the slotting shot hole extends into the rock mass of the next cycle footage, so that the directional cavity free face is formed in the rock mass of the next cycle footage, the slotting process can be omitted in the next cycle, and the blasting operation of the next cycle can be completed only by arranging the auxiliary hole and the peripheral hole; in other words, cutting blasting only needs to be conducted once every two circulating footings, the tunneling construction efficiency can be greatly improved, and the construction cost is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of blasting technology, especially to a blasting charge structure. BACKGROUND

[0002] In the tunnel blasting engineering, the charge setting of the cut hole has a great influence on the overall effect of the tunnel face blasting. The blasting effect of the cut hole is to break down some rocks on the working face to create a blasting cavity to form a free surface, and the blasting effect directly affects the blasting forming results of the subsequent auxiliary hole and the surrounding hole.

[0003] In the tunneling, it is advanced forward in a certain cycle footage. In the traditional blasting process, the drilling operation of the cut hole accounts for 35%-45% of the cycle time, and in the high strength rock stratum (compressive strength σ c > 80 MPa), it often faces the technical bottleneck of low cut efficiency and less than 80% of the utilization rate of the blast hole. When the ratio of cycle footage to rock mass strength (L / σ c ) exceeds 0.4, the residual rate caused by the insufficient fragmentation of the cut zone rock mass is 22%-30%, which seriously restricts the construction progress. Especially in deep buried tunnels, the deflection problem (more than 2°) caused by the cumulative positioning error of the drilling further aggravates the cut energy loss, resulting in an increase of 15%-20% in the single cycle cost. At present, although segmented charge structure is used, the energy transmission problem between multiple cycles is not solved, which often leads to low energy utilization rate in the cut hole. SUMMARY

[0004] Therefore, the utility model aims at providing a cavity preset cut hole charge structure, which improves the charge structure of the current cycle cut hole, forms a directional cavity free surface at the corresponding position of the next cycle while completing the fragmentation of the rock mass of the current cycle, and solves the technical problem of omitting the cut blasting for the next cycle.

[0005] The cavity preset cut hole charge structure of the utility model comprises a cut hole, which is composed of a main blasting section penetrating through the rock mass of the current cycle footage and an extended charge section extending into the rock mass of the next cycle footage, and the total hole depth of the cut hole is as follows:

[0006] L 总 = L0+ Δ L

[0007] Wherein, L0 is the length of the main blasting section, L0 is equal to the current cycle footage; Δ L is the length of the extended charge section, Δ L = 0.18L0*ln(1+σ c / 50), σ c is the uniaxial compressive strength of the rock mass.

[0008] The lengthened charge section is composed of a front charge section with a length of 0.8Δ L and a rear charge section with a length of 0.2Δ L ;

[0009] The main explosion section, the front charge section and the rear charge section are respectively filled with explosives, the explosives in each section are connected through a detonating cord, and the size relationship of the explosion speed of the explosives in each section is as follows:

[0010] The explosion speed of the explosives in the front charge section > the explosion speed of the explosives in the main explosion section > the explosion speed of the explosives in the rear charge section.

[0011] Further, a plurality of interval devices for separating the explosives are arranged in the rear charge section, the first interval device is arranged between the front charge section and the rear charge section, and the distance between the adjacent interval devices is S = 300 + 200 x (1-Kv), wherein Kv is a rock mass integrity coefficient, and the value range of Kv is 0.3-0.9.

[0012] The beneficial effects of the utility model are as follows:

[0013] The cavity preset type slotting hole charge structure of the utility model can extend the slotting blast hole into the rock mass of the next cycle footage, form a directional cavity free face in the rock mass of the next cycle footage, omit the slotting process in the next cycle, and only need to arrange auxiliary holes and peripheral holes to complete the blasting operation of the next cycle, that is, only need to perform slotting blasting once every two cycle footage, can greatly improve the tunnel excavation construction efficiency and reduce the construction cost. By filling the explosives with different powers in the main explosion section, the front charge section and the rear charge section, buffering the explosion energy of the main explosion section by the low explosion speed explosives in the rear charge section, achieving the energy gentle transition, and better avoiding the damage of the hole wall of the cavity of the rock mass free face of the next cycle footage caused by the stress mutation. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The utility model relates to a cavity preset type slotting hole charge structure. DETAILED DESCRIPTION

[0015] The utility model will be further described below in combination with the drawings and examples.

[0016] As shown in the drawings, the cavity preset type slotting hole charge structure of the utility model includes a slotting blast hole, the slotting blast hole is composed of a main explosion section 1 penetrating the rock mass of the current cycle footage and a lengthened charge section extending into the rock mass of the next cycle footage, and the total hole depth of the slotting blast hole is as follows:

[0017] L 总 = L0 + Δ L

[0018] Wherein, L0 is the length of the main explosion section, L0 is equal to the current cycle footage; Δ LTo extend the length of the charge section, Δ L =0.18L0×ln(1+σ c / 50), σ c The uniaxial compressive strength of the rock mass. The length of the extended charge section Δ L Two core parameters need to be balanced: the current cycle advance L0: the greater the cut depth, the larger the pre-set cavity needs to cover the next cycle range; and the rock mass strength σ. c High-strength rock masses require longer energy accumulation sections to form a continuous cavity. The inhibitory effect of rock mass strength on the extension of the charge section is nonlinear (high-strength rock masses require a significant increase in ΔL, but the rate of increase decreases). In this embodiment, Δ... L Choosing a logarithmic function can accurately fit this relationship, while introducing a correction term "1+σ". c / 50” can avoid σ c Negative values ​​occur at pressures <50MPa; ensure ΔL≥0. The total borehole depth designed in this way can automatically adapt to soft rock (σ). c When the pressure is approximately 30 MPa, ΔL≈0.1L0) to hard rock (σ c =At 150MPa, ΔL≈0.25L0) can avoid the risk of stuck drill pipe caused by ultra-deep drilling, reduce the waste of explosives and drilling costs, and reduce the overall construction cost.

[0019] The extended charge section has a length of 0.8Δ L The preload section 2 has a length of 0.2Δ. L It consists of three post-loading sections.

[0020] The main detonation section, the pre-charge section, and the post-charge section are each filled with explosive 4. The explosives in each section are connected by detonating cord 5, and the detonation velocities of the explosives in each section are in the following order:

[0021] The detonation velocity of the pre-charge section is greater than that of the main detonation section, which is greater than that of the post-charge section.

[0022] During detonation, the explosive in the main detonation section 4 is detonated first, followed by the explosive in the follow-up charge section 3, and finally the explosive in the pre-charge section 2. The explosive in the main detonation section breaks up the current cycle rock mass, creating a free face on it. The pre-charge section 2 uses high-power explosives, which can better overcome the rock clamping force, breaking up and ejecting the rock from the cut section, thus creating a free face cavity in the next cycle rock mass. The explosion energy difference between the main detonation section 4 and the pre-charge section 2 is significant. By setting low-detonation-velocity explosives in the charge section 3, a smooth energy transition is achieved, avoiding stress abrupt changes that could damage the borehole wall. Without the follow-up charge section for transition, the peak pressure of the shock wave transmitted from the main detonation section to the cavity section increases by approximately 62%, which can easily lead to premature detonation of the cavity section and affect the cavity formation effect.

[0023] In this embodiment, the pre-set cavity slotting hole charging structure extends the slotting blast hole into the rock mass of the next cycle of advance. By filling the main blasting section, the pre-charge section, and the post-charge section with explosives of different powers, a directional cavity free face is formed in the rock mass of the next cycle of advance. In this way, the slotting process can be omitted in the next cycle. Only auxiliary holes and peripheral holes need to be arranged to complete the blasting operation of the next cycle. That is, only one slotting blast is needed every two cycles of advance, which can greatly improve the efficiency of tunnel excavation and reduce construction costs.

[0024] As an improvement to the above embodiment, the post-charge section is provided with several spacers 6 for separating the explosives. The first spacer 6 is located between the pre-charge section and the post-charge section. The distance between adjacent spacers 6 is S = 300 + 200 × (1 - Kv), where Kv is the rock mass integrity coefficient, and the value of Kv ranges from 0.3 to 0.9. The lower the Kv value, the more fractured the rock mass, and the larger the spacing between the explosive charges needs to be to reduce the risk of borehole collapse caused by stress concentration; conversely, for intact rock mass (high Kv), the spacing can be reduced to increase energy density. The spacing distance has an approximately linear relationship with (1 - Kv). In this embodiment, the basic value of 300 mm in the spacing formula S = 300 + 200 × (1 - Kv) ensures the minimum spacing requirement (S = 300 mm when Kv = 1 for extremely intact rock mass); the coefficient 200 mm is the weight value of the rock mass fracture degree (1 - Kv), which is determined through Monte Carlo simulation optimization. This formula can automatically match rock mass conditions: from fractured zone (S=440mm when Kv=0.3) to intact rock mass (S=320mm when Kv=0.9). By setting spacers in the post-charge section 3 to achieve interval charging, the main detonation section and the pre-charge section are physically separated, which can better prevent the risk of sympathetic detonation and help improve the cavity forming qualification rate.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A cased hole charge configuration for cavity-priming, characterized by: The undercutting borehole comprises a main blasting section penetrating through the current cycle footage rock mass and an extended charge section extending into the next cycle footage rock mass, and the total hole depth of the undercutting borehole is as follows: L 总 = L0+ Δ L Wherein, L0 is the length of the main blasting section, L0 is equal to the current cycle footage; Δ L In order to prolong the length of the charge section, Δ L = 0.18L0 x ln(1+σ c / 50), σ c is the uniaxial compressive strength of rock mass; The elongated charge section consists of a front charge section of length 0.8Δ L and a rear charge section of length 0.2Δ L ; The main blasting section, the front charge section and the rear charge section are respectively filled with explosives, the explosives in each section are connected through a detonating cord, and the size relationship of the detonation velocities of the explosives in each section is as follows: The detonation velocity of the explosives in the front charge section > the detonation velocity of the explosives in the main blasting section > the detonation velocity of the explosives in the rear charge section.

2. The cased cavity pre-initiated cut slot charge structure of claim 1, wherein: A plurality of interval devices for separating the explosives are arranged in the rear charge section, the first interval device is arranged between the front charge section and the rear charge section, and the distance between the adjacent interval devices is S = 300 + 200 x (1-Kv), wherein Kv is a rock mass integrity coefficient, and the value range of Kv is 0.3-0.9.

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