Construction scheme generation method and system for reducing damage of vertical shaft blasting expanding excavation to tunnel roof below

Abstract

The invention discloses a construction scheme generation method and system for reducing damage of vertical shaft blasting expanding excavation to a tunnel roof below. The method comprises the following steps that the rock mechanical property of a construction site is measured; determining the construction design parameters and explosive performance of the vertical shaft expanding excavation blasting at the junction; calculating the thickness of the reserved protective layer based on the rock mechanical property, the design parameters and the explosive performance; and designing a construction scheme based on the reserved protective layer. According to the invention, the explosion damage range is deduced based on the principles of explosion stress wave propagation and reflection stretching at a free surface; during field application, the damage range can be determined only by obtaining related parameters such as rock mechanical properties in advance, so that the thickness of the protective layer needing to be reserved is determined; when the device is used for reducing the damage of vertical shaft blasting expanding excavation to the lower horizontal tunnel roof, no special device is needed, and the equipment and labor cost is directly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of shaft blasting and excavation, and in particular relates to a construction scheme generation method and system for reducing damage to a tunnel roof below caused by shaft blasting and excavation. Background Art

[0002] The reverse well method has the advantages of fast drilling speed, high work efficiency, safe construction, low labor intensity, high construction precision and good quality, and has become the main method for vertical shaft excavation. When using the reverse well method to excavate a vertical shaft, a reverse well drilling rig is generally used to drill a pilot hole, and then the drilling and blasting method is used to expand the excavation from top to bottom to the designed diameter of the vertical shaft. When the vertical shaft blasting construction position reaches the junction of the horizontal tunnel and the vertical shaft, the horizontal tunnel vault is easily damaged due to the reflection and stretching effect of the blasting stress wave on the free surface. Therefore, it is necessary to design a construction plan to reduce the damage of the vertical shaft blasting expansion to the tunnel roof below. Summary of the invention

[0003] The present invention aims to solve the deficiencies of the prior art and provides the following solutions:

[0004] A construction scheme generation method and system for reducing the damage to the tunnel roof below caused by shaft blasting and excavation, comprising the following steps:

[0005] Determine the rock mechanical properties at the construction site;

[0006] Determine the design parameters and explosive performance of the vertical shaft expansion blasting construction at the junction;

[0007] Calculating the thickness of the reserved protective layer based on the rock mechanical properties, the design parameters and the explosive properties;

[0008] A construction plan is designed based on the reserved protective layer.

[0009] Preferably, the method for determining the mechanical properties of the rock comprises: selecting rock samples from the construction site and determining them through static tests. The mechanical properties of the rock include: the wave velocity C of the rock p , rock density ρ, Poisson's ratio μ, tensile strength σ t .

[0010] Preferably, the design parameters and explosive performance include: explosive density ρ0, explosive detonation velocity D, charge structure, blasthole diameter R b and charge diameter R c .

[0011] Preferably, the method for calculating the thickness of the reserved protective layer includes:

[0012]

[0013] Where w represents the reserved protective layer thickness, P represents the initial shock wave pressure peak on the blast hole wall after the explosive explodes, and r b represents the blasthole radius, and α represents the load propagation attenuation exponent.

[0014] Preferably, the initial shock wave pressure on the blast hole wall after the explosive explodes includes two different scenarios:

[0015] The peak pressure P on the borehole wall using the coupled charge structure is:

[0016]

[0017] Where P0 represents the detonation pressure of the explosive, and γ is the adiabatic expansion index of the detonation product;

[0018] The peak pressure P on the borehole wall using an uncoupled charge structure is:

[0019]

[0020] Where K represents the radial charge decoupling coefficient, l e represents the axial coefficient and n represents the pressure increase coefficient.

[0021] Preferably, the designed construction scheme includes:

[0022] When constructing a horizontal tunnel near a vertical shaft, the thickness of the reserved protective layer in the direction perpendicular to the vertical shaft is w, and the reserved range of the reserved protective layer along the horizontal tunnel direction is the vertical shaft diameter + 2w;

[0023] The shaft blasting and excavation construction is carried out by using the circular step blasting scheme. The blasting sequence is from the inside to the outside, first blasting the main blast hole, and then blasting the surrounding light blast holes.

[0024] The reserved protective layer is constructed by smooth blasting, dense blast holes, and air-spaced charge.

[0025] The present invention also provides a construction scheme generation system for reducing the damage to the tunnel roof below caused by shaft blasting and excavation, the system applying any of the above methods, including: a rock determination module, a construction parameter design module, a thickness calculation module and a scheme generation module;

[0026] The rock measurement module is used to measure the mechanical properties of rocks at the construction site;

[0027] The construction parameter design module is used to determine the construction design parameters and explosive performance of the vertical shaft expansion blasting at the junction;

[0028] The thickness calculation module calculates the thickness of the reserved protective layer based on the rock mechanical properties, the design parameters and the explosive properties;

[0029] The scheme generating module designs a construction scheme based on the reserved protective layer.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention deduces the scope of explosion damage based on the principle of explosion stress wave propagation and reflected stretching at the free surface. When applied on site, it is only necessary to obtain relevant parameters such as rock mechanical properties in advance to determine the damage scope, thereby determining the required reserved protective layer thickness. The present invention is used to reduce the damage to the horizontal tunnel roof below caused by shaft blasting and expansion, without the need to use special devices, thereby directly reducing equipment and labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solution of the present invention, 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 creative labor.

[0033] Figure 1 A schematic diagram of a method flow chart of an embodiment of the present invention;

[0034] Figure 2 It is a schematic diagram of a cross section perpendicular to the horizontal tunnel direction of an embodiment of the present invention;

[0035] Figure 3 It is a schematic cross-sectional view along the horizontal tunnel direction of an embodiment of the present invention. DETAILED DESCRIPTION

[0036] 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.

[0037] 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.

[0038] Example

[0039] A certain shaft excavation project uses the reverse well method. In this embodiment, if Figure 1 As shown, a construction scheme generation method for reducing the damage to the tunnel roof below caused by shaft blasting and excavation comprises the following steps:

[0040] S1. Determine the rock mechanical properties at the construction site.

[0041] Rock samples were selected from the construction site and tested in the laboratory for dynamic and static rock tests. The wave velocity of the rock above the horizontal tunnel top plate was 5174.98m / s and the density was 2830kg / m 3 , Poisson's ratio is 0.25, and the tensile strength is 9.51Mpa.

[0042] S2. Determine the design parameters for the blasting construction of the vertical shaft expansion at the junction and the performance of the explosives.

[0043] The shaft blasting and excavation plan is annular step blasting, uncoupled charging, blasthole diameter is 42mm, axial charging coefficient is 0.76. The explosive is No. 2 rock emulsion explosive, with a diameter of 32mm and an uncoupled coefficient of 1.31. The density of the explosive is 1.2g / cm 3 , the detonation speed of the explosive is 3200m / s.

[0044] S3. Calculate the thickness of the reserved protective layer based on the rock mechanical properties, design parameters and explosive properties.

[0045] In this embodiment, when the explosive stress wave encounters a free surface during propagation, it will be reflected and changed from a compression wave to a tensile wave. Since the tensile strength of the rock is much smaller than the compressive strength, if the tensile stress is greater than the tensile strength of the rock, the rock will crack and fail. The stress wave will gradually attenuate when propagating in the rock. By reserving a protective layer, on the one hand, the free surface can be kept away from the horizontal tunnel roof, and on the other hand, the process of stress wave attenuation is prolonged, so that the amplitude of the reflected tensile wave is reduced.

[0046] The rock failure conditions are:

[0047] σ 拉 ≥σ t

[0048] Among them, σ 拉 represents tensile stress;

[0049] Further:

[0050]

[0051] According to the above formula, we can derive:

[0052]

[0053] The reserved protective layer thickness can be calculated by taking the equal sign from the above formula, that is, the method for calculating the reserved protective layer thickness is:

[0054]

[0055] Where w represents the reserved protective layer thickness, P represents the initial shock wave pressure peak on the blast hole wall after the explosive explodes, and r brepresents the blasthole radius, and α represents the load propagation attenuation exponent.

[0056] The initial shock wave pressure on the blast hole wall after the explosive explosion includes two different scenarios:

[0057] The peak pressure P on the borehole wall using the coupled charge structure is:

[0058]

[0059]

[0060] Where P0 represents the detonation pressure of the explosive, ρ and ρ0 represent the density of rock and explosive respectively, and C p and D represent the wave velocity in rock and the detonation velocity of explosives respectively, and γ represents the adiabatic expansion index of detonation products, which is generally taken as 3.

[0061] The peak pressure P on the borehole wall using an uncoupled charge structure is:

[0062]

[0063] Where K represents the radial charge decoupling coefficient, which is the ratio of the borehole radius to the charge radius; l e represents the axial charging coefficient; n represents the pressure increase coefficient, generally n=10.

[0064] The thickness of the reserved protective layer calculated according to the above formula is 61.6 cm.

[0065] S4. Design construction plan based on reserved protective layer

[0066] The designed construction plan includes: horizontal tunnel excavation construction near the vertical shaft, such as Figure 2 and Figure 3 As shown, a protective layer with a thickness of w = 61.6 cm should be reserved along the vertical shaft direction, and the reserved range of the protective layer along the horizontal tunnel direction is the shaft diameter + 2 × 61.6 cm. The vertical shaft blasting and excavation construction uses a ring-like step blasting scheme to carry out the vertical shaft blasting and excavation construction. The blasting sequence is from the inside to the outside, first blasting the main blasting hole, and then blasting the surrounding light blasting holes; the construction of the reserved protective layer adopts the smooth blasting method, dense blasting holes, and air interval charging.

[0067] Embodiment 2

[0068] In this embodiment, a construction scheme generation system for reducing the damage to the lower tunnel roof caused by shaft blasting and excavation includes: a rock determination module, a construction parameter design module, a thickness calculation module and a scheme generation module.

[0069] The rock determination module is used to determine the rock mechanical properties at the construction site.

[0070] The method for determining the mechanical properties of rock includes: selecting rock samples from the construction site and determining them through static tests. The mechanical properties of rock include: the wave velocity C of the rock p , rock density ρ, Poisson's ratio μ, tensile strength σ t .

[0071] The construction parameter design module is used to determine the construction design parameters of the vertical shaft expansion blasting at the junction and the performance of the explosives.

[0072] Design parameters and explosive performance include: explosive density ρ0, explosive detonation velocity D, charge structure, blasthole diameter R b and charge diameter R c In this embodiment, the basic information of the explosive density ρ0 and the explosive detonation velocity D can be obtained when the explosive model is determined. Charge structure, blast hole diameter R b and charge diameter R c It is directly obtained from the design of blasting parameters for shaft expansion.

[0073] The thickness calculation module calculates the thickness of the reserved protective layer based on the rock mechanical properties, design parameters and explosive properties.

[0074] Methods for calculating the thickness of the reserved protective layer include:

[0075]

[0076] Where w represents the reserved protective layer thickness, P represents the initial shock wave pressure peak on the blast hole wall after the explosive explodes, and r b represents the blasthole radius, and α represents the load propagation attenuation exponent.

[0077] The initial shock wave pressure on the blast hole wall after the explosion includes two different scenarios: The peak pressure P on the blast hole wall using the coupled charge structure is:

[0078]

[0079] Among them, P0 represents the detonation pressure of the explosive, γ is the adiabatic expansion index of the detonation product; the peak pressure P on the blast hole wall using the uncoupled charge structure is:

[0080]

[0081] Where K represents the radial charge decoupling coefficient, l e represents the axial coefficient and n represents the pressure increase coefficient.

[0082] The scheme generation module designs the construction scheme based on the reserved protective layer.

[0083] The designed construction plan includes: when the horizontal tunnel excavation construction is close to the vertical shaft, the thickness of the reserved protective layer in the direction perpendicular to the vertical shaft is w, and the reserved range of the reserved protective layer along the horizontal tunnel direction is the vertical shaft diameter + 2w; the shaft blasting and excavation expansion construction is carried out by using the annular step blasting plan, and the blasting sequence is detonated in sections from the inside to the outside, first the main blasting hole is blasted, and then the surrounding light blasting holes are detonated. In this embodiment, the shaft blasting and excavation expansion plan is annular step blasting, the main blasting hole adopts continuous charging and is evenly arranged in a ring shape, the bottom of the light blasting hole is deeper than the bottom of the main blasting hole, interval charging is adopted, and the bottom is strengthened. The detonation system adopts an electronic detonator dedicated to electronic detonators for detonation, and the detonation network adopts an in-hole micro-difference method. The blasting sequence is detonated in sections from the inside to the outside, first the main blasting hole is blasted, and then the surrounding light blasting holes are detonated, and the smooth holes are detonated at the same time to ensure the smooth blasting effect; the construction of the reserved protective layer adopts the smooth blasting method, dense blasting holes, and air interval charging.

[0084] The above embodiments are only descriptions of the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for generating a construction plan to reduce the damage to the tunnel roof caused by shaft blasting and excavation, characterized in that: The following steps are involved: Determine the mechanical properties of rocks at the construction site; Determine the design parameters and explosive performance of the vertical shaft expansion blasting construction at the junction; Calculating the thickness of the reserved protective layer based on the rock mechanical properties, the design parameters and the explosive properties; A construction plan is designed based on the reserved protective layer.

2. A construction scheme generation method for reducing damage to the tunnel roof caused by shaft blasting and excavation according to claim 1, characterized in that: The method for measuring the mechanical properties of the rock includes: selecting rock samples from the construction site and measuring them through static tests. The mechanical properties of the rock include: the wave velocity C of the rock p , rock density ρ, Poisson's ratio μ, tensile strength σ t .

3. A construction scheme generation method for reducing damage to the tunnel roof caused by shaft blasting and excavation according to claim 2, characterized in that: The design parameters and explosive performance include: explosive density ρ0, explosive detonation velocity D, charge structure, blast hole diameter R b and charge diameter R c .

4. A construction scheme generation method for reducing damage to the tunnel roof caused by shaft blasting and excavation according to claim 3, characterized in that: The method for calculating the thickness of the reserved protective layer includes: Where w represents the reserved protective layer thickness, P represents the initial shock wave pressure peak on the blast hole wall after the explosive explodes, and r b represents the blasthole radius, and α represents the load propagation attenuation exponent.

5. A construction scheme generation method for reducing damage to the tunnel roof caused by shaft blasting and excavation according to claim 4, characterized in that: The initial shock wave pressure on the blast hole wall after the explosive explosion includes two different scenarios: The peak pressure P on the borehole wall using the coupled charge structure is: Where P0 represents the detonation pressure of the explosive, and γ is the adiabatic expansion index of the detonation product; The peak pressure P on the borehole wall using an uncoupled charge structure is: Where K represents the radial charge decoupling coefficient, l e represents the axial coefficient and n represents the pressure increase coefficient.

6. A construction scheme generation method for reducing damage to the tunnel roof caused by shaft blasting and excavation according to claim 1, characterized in that: The designed construction plan includes: When constructing a horizontal tunnel near a vertical shaft, the thickness of the reserved protective layer in the direction perpendicular to the vertical shaft is w, and the reserved range of the reserved protective layer along the horizontal tunnel direction is the vertical shaft diameter + 2w; The shaft blasting and excavation construction is carried out by using the circular step blasting scheme. The blasting sequence is from the inside to the outside, first blasting the main blast hole, and then blasting the surrounding light blast holes. The reserved protective layer is constructed by smooth blasting, dense blast holes, and air-spaced charge.

7. A construction plan generation system for reducing the damage to the tunnel roof caused by shaft blasting and excavation, the system applying the method according to any one of claims 1 to 6, characterized in that: include: Rock determination module, construction parameter design module, thickness calculation module and solution generation module; The rock measurement module is used to measure the mechanical properties of rocks at the construction site; The construction parameter design module is used to determine the construction design parameters and explosive performance of the vertical shaft expansion blasting at the junction; The thickness calculation module calculates the thickness of the reserved protective layer based on the rock mechanical properties, the design parameters and the explosive properties; The scheme generating module designs a construction scheme based on the reserved protective layer.

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