CN103063091B - Deep-buried tunnel full-section millisecond blasting method - Google Patents

Abstract

Provided is a deep-buried tunnel full-section millisecond blasting method. According to density distribution positions of elastic strain energy on a tunnel face, a millisecond electric detonator is adopted to divide cutting blast holes into two sections to perform detonation, spallation blast holes, buffer blast holes and light exposure blast holes are respectively divided into four sections to perform detonation, the number of the blast holes of each section is approximate, and blasting is performed from inside to outside and from low strain energy intensity to high strain energy intensity in each circle. The releasing rate and strength of the elastic strain energy are controlled by changing blast hole priming circuits, and surrounding rock power disturbance caused by quick releasing of strain energy is further weakened. By means of the deep-buried tunnel full-section millisecond blasting method, the peak value mass point vibration velocity caused by quick releasing of strain energy on an excavation face is only 40-50% velocity by means of a conventional blasting method. The deep-buried tunnel full-section millisecond blasting method can be widely applied to deep-buried tunnel blasting excavation in the fields of water and electricity, traffic, mines and the like.

Description

A kind of deep-lying tunnel tunneling boring millisecond blasting method

Technical field

The present invention relates to Geotechnical Engineering field, specifically a kind of deep-lying tunnel tunneling boring millisecond blasting method.

Background technology

Along with the increase day by day of the deeply further and mining mineral resource degree of depth of the regional construction of hydropower facilities of Southwestern China, the Blasting Excavation of deep-lying tunnel is more prevalent in engineering construction.Because buried depth is comparatively large or tectonic movement is strong, the crustal stress level of tunnel rock mass is often higher, have accumulated huge elastic strain energy.Along with explosive charge in Blasting Excavation process, by the unexpected removal of crustal stress in the moment fragmentation of excavation rock mass, excavation face, the elastic strain energy be stored in rock mass discharges fast to free face, causes the surrouding rock stress near face to adjust rapidly.Because a rate of advance is fast, the unexpected release of this Large strain energy may cause country rock burst large deformation, and brings out violent rock burst further, affects construction speed and cavern's Stability Analysis of Structures, and the safety of serious threat workmen and equipment.

Rock mass produces distortion under three-dimensional compressive stress effect, supposes that this physical process and the external world do not have heat exchange, and in the principal stress space, rock mass elastic strain energy density e is:

$e=\frac{1}{2E}[{{\mathrm{\σ}}_1}^2+{{\mathrm{\σ}}_2}^2+{{\mathrm{\σ}}_3}^2-2\mathrm{\μ}({\mathrm{\σ}}_1{\mathrm{\σ}}_2+{\mathrm{\σ}}_2{\mathrm{\σ}}_3+{\mathrm{\σ}}_1{\mathrm{\σ}}_3)]---\left(1\right)$

In formula: σ _jfor principal stress, j=1,2,3; E is Modulus of Elasticity of Rock Mass; μ is rock mass Poisson's ratio.

The rock mass of certain volume contains n rock element, and the strain energy U comprised is:

$U=\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{e}_k\·V_k---\left(2\right)$

In formula: V _kfor the volume of a kth rock element.

By excavation rock mass because stress removal discharges its all elastic strain energy, excavation causes the change retaining rock stress field around simultaneously, and because distortion and Stress relief are also by energy certain for release, this two parts energy sum is exactly the energy of excavation release:

ΔU＝U ₁+U ₂-U ₂′ (3)

In formula: U ₁, U ₂the elastic strain energy of rock mass and surrounding rock body is excavated before being respectively excavation; U ₂' for excavating the elastic strain energy of rear surrounding rock body.

Therefore, the tunnel blasting excavation of High Ground Stress Areas will control to excavate the country rock energetic disturbance caused from blast and strain energy release two aspect.And current blasting excavation is often only for blast itself, the methods such as reduced charge, short drilling depth and partial excavation are adopted to control from explosive quantity in a sound the country rock energetic disturbance caused that explodes.Although shortening drilling depth and partial excavation also reduce the strain energy of single explosion release, can reach certain effect, this is a kind of simple to sacrifice the control method that drivage efficiency is cost.

Summary of the invention

The present invention is directed to the existing construction technology situation of deep-lying tunnel Blasting Excavation, the country rock energetic disturbance caused is discharged fast for weakening elastic strain energy, there is provided a kind of deep-lying tunnel tunneling boring millisecond blasting method of optimization, to reach accelerating construction progress, to ensure the object of cavern's Stability Analysis of Structures and staff's personal safety.

Principle of the present invention is: by changing big gun hole blasting circuit, controls rate of release and the intensity of elastic strain energy, and then weakens strain energy and discharge the country rock energetic disturbance caused fast.Under deep-lying tunnel is often in non-hydrostatic condition, after slotting district is formed, strain energy density non-uniform Distribution on face; If according to the extreme value distribution position of strain energy density, avalanche big gun hole, buffering big gun hole and the equal segmentation in light quick-fried big gun hole are detonated, each section of big gun hole number is roughly equal, and the rock mass of first explosion strain energy density lower position, after detonating such early stage, due to Stress relief, reduce the energy of the strain energy density higher part position rock mass of ensuing blast, thus control strain energy rate of release and intensity, strain energy more evenly discharges when ensure that each section of explosion; Simultaneously because the rock mass stress of strain energy density lower position is lower, first detonate be conducive to rock mass cracking, crackle is through, to reach good crushing effect.

A kind of deep-lying tunnel tunneling boring of the present invention millisecond blasting method, its step is as follows:

(1) tunnel blasting excavation is front according to geology survey data or numerical computations, determines principal stress level and the direction for the treatment of tunnel excavation rock mass;

(2) on excavation face, arrange undercut blast hole, avalanche big gun hole, buffering big gun hole and the quick-fried big gun hole of light according to existing boring and data of explosive filled from inside to outside successively, carry out blast hole projectile filling;

(3) according to principal stress level and direction, to be taken up an official post tangent stress by face after the secondary stress state computation formula of deep-lying tunnel elasticity distribution or numerical computations determination slotting, and in conjunction with the elastic modelling quantity of rock mass and Poisson's ratio, by the elastic strain energy Density Distribution on face after elastic strain energy density calculation formula or numerical computations determination slotting;

(4) undercut blast hole divides two sections of explosions, according to the extreme value distribution position of elastic strain energy density on face after slotting, four sections of explosions are divided in avalanche big gun hole, buffering big gun hole and the quick-fried big gun hole of light, carry out explosion according to from inside to outside, respectively enclosing internal strain energy density order from low to high.

Described undercut blast hole, avalanche big gun hole, buffering big gun hole and the quick-fried big gun hole of light adopt millisecond electric detonator segment blast, and each section of big gun hole number is close.

The advantage of a kind of deep-lying tunnel tunneling boring of the present invention millisecond blasting method is:

(1), in existing boring layout and data of explosive filled basis, in conjunction with the elastic strain energy Density Distribution on face, control rate of release and the intensity of elastic strain energy by changing big gun hole blasting circuit, operation is simple;

(2), after detonating early stage, due to Stress relief, reduce the energy of the strain energy density higher part position rock mass of ensuing blast, thus control strain energy rate of release and intensity, strain energy more evenly discharges when ensure that each section of explosion; Simultaneously because the rock mass stress of strain energy density lower position is lower, first detonate be conducive to rock mass cracking, crackle is through, to reach good crushing effect;

(3) compare with conventional blasting method method, obviously can reduce elastic strain energy and discharge the country rock energetic disturbance caused fast, in excavation face, strain energy discharges the 40-50% that the peak particle velocity caused is only conventional blasting method method fast; The industry deep-lying tunnel Blasting Excavation such as water power, traffic, mine can be widely used in.

Accompanying drawing explanation

Fig. 1 is tunnel principal direction of stress schematic diagram.

Fig. 2 is steel for shot and conventional blasting sequence schematic diagram in prior art.

Fig. 3 is that slotting district forms elastic strain energy Density Distribution schematic diagram on rear face.

Fig. 4 is the blasting sequence schematic diagram of blasting method of the present invention.

Fig. 5 discharges according to the elastic strain energy of FEM calculation the country rock particle vibration sum velocity contrast schematic diagram brought out fast.

Mark in figure: 1 is tunnel, and 2 is maximum principal stress on face, and 3 is minimum principal stress on face, and 4 is big gun hole, and 5 is elastic strain energy density curve, numeral represent each segment number of each circle.

Detailed description of the invention

In certain massif, drill-blast tunnelling diameter is the circular tunnel 1 of 10m, and as shown in Figure 1, adopt tunneling boring millisecond blasting excavation, conventional blasting sequence is each circle big gun hole homogeneous section explosion from inside to outside, as shown in Figure 2.Tunnel buried depth is large, and for there is the possibility of large deformation and rock burst when alleviating Blasting Excavation, the present invention optimizes this blasting construction method in original explosion design basis, specific as follows:

1., before tunnel 1 Blasting Excavation, according to geology survey data or numerical computations, determine level and the direction of minimum principal stress 3 on maximum principal stress 2, face on tunnel rock mass face, assuming that σ ₁=40MPa, σ ₃=20.0MPa, principal direction of stress as shown in Figure 1.

2. on excavation face, arrange big gun hole 4 and powder charge according to original explosion design parameter, arrange 2 circle undercut blast hole, 3 circle avalanche big gun holes, 1 circle buffering big gun hole and the 1 circle quick-fried big gun hole of light from inside to outside successively, cutting method adopts the parallel, straight slotting of band emptying aperture, as shown in Figure 2.

3. according to principal stress level and the direction of tunnel rock mass, after slotting district is formed, to be taken up an official post tangent stress by the secondary stress state computation formula of buried circular tunnel elasticity distribution or numerical computations determination face, to substitute in (1) formula and in conjunction with the elastic modelling quantity of rock mass and Poisson's ratio, to calculate the elastic strain energy density of any point.If the elastic modelling quantity of rock mass equals 40GPa, Poisson's ratio equals 0.22, for the rock mass at light quick-fried big gun hole place, elastic strain energy Density Distribution as shown in Figure 3, there is maximum in minimum principal stress 3 direction strain energy density on face, and on face, on maximum principal stress 2 direction, minimum appears in strain energy density.

4. undercut blast hole adopts millisecond electric detonator to divide 2 sections to detonate.According to the extreme value distribution position of strain energy density after slotting, avalanche big gun hole, buffering big gun hole and the quick-fried big gun hole of light all adopt millisecond electric detonator to divide 4 sections to detonate, and each section of big gun hole number is roughly equal, the rock mass of first explosion strain energy density lower position, as shown in Figure 4.For the quick-fried shot hole blasting of light, according to 21-22-23-24 sequence blasting, after being in the 21st section of strain energy density lower position and 22 sections of explosions, due to Stress relief, release the elastic strain energy of closing on not quick-fried rock mass, make originally to be in the 23rd section of Large strain energy position and the strain energy of the 24th section reduces, thus when controlling the rate of release of strain energy and intensity, guarantee each section of explosion, strain energy more evenly discharges, and has reached the object weakening country rock energetic disturbance.It should be noted that, its blasting sequence of position that described strain energy density is identical is adjustable, in shot hole blasting as quick-fried in light, except according to except said sequence, also can according to the order of 22-21-24-23, can also according to the order of 21-22-24-23, or according to the order of 22-21-23-24, circle internal strain energy density order from low to high all can be met.

On face, on minimum principal stress 3 direction, the strain energy density of rock mass is higher, at this place, deep-lying tunnel tunneling boring millisecond blasting method of the present invention to country rock energetic disturbance to weaken effect the most obvious.During shot hole blasting quick-fried for light, elastic strain energy discharges the country rock particle vibration brought out fast, before and after employing blasting method of the present invention, be positioned at the peak vibration sum velocity of the particle on face on minimum principal stress 3 direction as shown in Figure 5 (according to FEM calculation).After adopting blasting method of the present invention, apart within the 3.0m of outline excavation face, elastic strain energy discharges fast brings out the country rock energetic disturbance caused and obviously reduces, and on outline excavation face, peak particle vibration sum velocity is 45% of conventional blasting method method.

Above-described specific embodiment; further detailed description has been carried out to object of the present invention, technical scheme and beneficial outcomes; be understood that; the foregoing is only specific embodiments of the invention; be not limited to the present invention; all in the spirit and principles in the present invention and so on, any amendment made, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (2)

1. a deep-lying tunnel tunneling boring millisecond blasting method, is characterized in that comprising the steps:

(1) tunnel blasting excavation is front according to geology survey data, determines principal stress level and the direction for the treatment of tunnel excavation rock mass;

(2) on excavation face, arrange undercut blast hole, avalanche big gun hole, buffering big gun hole and the quick-fried big gun hole of light according to existing boring and data of explosive filled from inside to outside successively, carry out blast hole projectile filling;

(3) according to principal stress level and direction, to be taken up an official post tangent stress by face after the secondary stress state computation formula determination slotting of deep-lying tunnel elasticity distribution, and in conjunction with the elastic modelling quantity of rock mass and Poisson's ratio, by the elastic strain energy Density Distribution on face after elastic strain energy density calculation formula determination slotting;

(4) undercut blast hole divides two sections of explosions, according to the extreme value distribution position of elastic strain energy density on face after slotting, four sections of explosions are divided in avalanche big gun hole, buffering big gun hole and the quick-fried big gun hole of light, carry out explosion according to from inside to outside, respectively enclosing internal strain energy density order from low to high.

2. deep-lying tunnel tunneling boring millisecond blasting method as claimed in claim 1, is characterized in that: described undercut blast hole, avalanche big gun hole, buffering big gun hole and the quick-fried big gun hole of light adopt millisecond electric detonator segment blast, and each section of big gun hole number is close.