CN108222937A - Secondary top board structure quantitative analysis and its evaluation method based on inclined seam exploitation - Google Patents
Secondary top board structure quantitative analysis and its evaluation method based on inclined seam exploitation Download PDFInfo
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Abstract
The invention discloses a kind of secondary top board structure quantitative analysis based on inclined seam exploitation and its evaluation methods, belong to coal mine coal seam production technique field.Which solve many production problems faced in inclined seam recovery process in the prior art.Evaluation method of the present invention includes：It determines that superjacent adopts the extent of the destruction to bottom plate first, then determines that the extent of the destruction to top plate is adopted in lower section, i.e. the destruction height to top plate is adopted in lower section, using Exploring Loose Rock Country in Tunnels theory come deployment analysis etc.；Then Exploring Loose Rock Country in Tunnels surveyed, analyzed, country rock is divided into small relaxation zone, middle relaxation zone and big relaxation zone according further to the size of relaxation zone；Finally, the secondary top board structure classification indicators of dynamic pressure are determined by the dual influence synthesis adopted.The present invention is for closely efficiently production has extremely important directive significance for inclined seam roadway surrounding rock control, guarantee mine safety under goaf.
Description
Technical field
The present invention relates to coal mine coal seam production technique fields, and in particular to a kind of secondary top plate based on inclined seam exploitation
Structure quantitative analysis and its evaluation method.
Background technology
During contiguous seams working from top down, underlying seam tunnel forms dynamic pressure under the dramatic impact of repeated mining
The secondary top board structure that goaf spoil is formed behind tunnel and superjacent exploitation.Compared with single coal bed is exploited, top plate
Apparent change has occurred in sand coated iron mold and mechanical mechanism.It is embodied in：Roadway surrounding rock deformation amount increases, and deformation is apparent, encloses
Rock cranny development, plastic zone range expand, and ore deposit pressure shows acutely or even induction tunnel overall collapse is caving or bump.
The production problem faced in inclined seam recovery process is necessarily more.
Invention content
Based on many problems that above-mentioned inclined seam in the prior art is faced in recovery process, the present invention proposes one
Kind of the secondary top board structure quantitative analysis exploited based on inclined seam and its evaluation method, this method under goaf closely
Inclined seam roadway surrounding rock control ensures that efficiently production has extremely important directive significance to mine safety.
Required technical problems to be solved are to achieve the above object：
For many technical barriers brought during closely inclined seam working from top down, it is put forward for the first time underlying seam
One kind " secondary top board structure " that tunnel is formed under the influence of repeated mining.How selective analysis back is away from top goaf
Interlamellar spacing and the secondary top board structure of dynamic pressure between inner link；How to realize to the quantitative forecast of secondary top board structure and sentence
Disconnected, how the secondary top board structure criterion of dynamic pressure determines.
In order to solve the above technical problems, the present invention proposes following technical scheme：
Secondary top board structure quantitative analysis and its evaluation method based on inclined seam exploitation, which is characterized in that wrap successively
Include following steps：
A, determine that superjacent adopts the extent of the destruction to bottom plate, i.e. gob floor rock stratum maximum plastic failure depth
hmax, calculated by formula (1)：
In formula (1), M-mining height, m；K-the factor of stress concentration, k=2；γ-overlying rock volume-weighted average, kN/m3；H—
Coal seam buried depth, m；C-coal seam cohesive force, MPa；φ-coal seam internal friction angle, °；F-coal seam and roof and floor friction coefficient,ξ-triaxial stress coefficient,φf- floor strata internal friction angle, °；
B, determine that the extent of the destruction to top plate is adopted in lower section, i.e. the destruction height to top plate is adopted in lower section, is enclosed using tunnel
Rock Supporting Theory of Broken Rock Zone determines, is divided into following sub-step：
B1, the country rock after roadway excavation is divided into relaxation zone, plastic zone and elastic region；
B2, the theory analysis for carrying out Exploring Loose Rock Country in Tunnels：
Rock mass is after excavating stress redistribution so that the stress distribution feature that secondary stress elastoplasticity occurs and deposits.For
Simplified theory analysis, it is believed that circular tunnel digging is P in continuous, homogeneous, isotropism, in the stress of primary rock0Uniformly should
In the field of force, when the secondary stress of hole wall exceeds the yield stress of rock mass, then wall rock mass in hole generates plastic zone, and plastic zone is a kind of pole
Equilibrium state is limited, according to Elasticity, the balance differential equation that each point stress is met is as shown in Equation 2：
In formula (2), σθ- circumference stress, kg/cm2；σr- radial stress, kg/cm2；That is investigated in r-plastic zone appoints
It anticipates the radius of a bit, cm；
B3, in plastic zone, since rock mass just starts to destroy, in state of limit equilibrium, each point stress should all meet not
That-Coulomb strength criterion, as shown in formula (3)：
In formula：The cohesive force of c-country rock, kg/cm2；- internal friction angle, °；σθ- circumference stress, kg/cm2；σr- radially
Stress, kg/cm2；The radius at any point investigated in r-plastic zone, cm.
Formula (3) is substituted into formula (2) to obtain shown in equation general solution such as formula (4)：
c1For undetermined constant, determined according to boundary condition：On tunnel-surrounding, r=r0, σr=Pi；PiIt is stent to enclosing
The counter-force of rock；
By r0And PiSubstitution formula (4) obtains formula (5)：
B4, formula (5) substitution formula (3), (4) are obtained shown in plastic zone stress such as formula (6)：
B5, formula (6) is substituted into the condition σ that elastic stress meetsr+σθ=2P0Obtain formula (7)：
C, Exploring Loose Rock Country in Tunnels surveyed, analyzed, country rock is divided into little Song according further to the size L of relaxation zone
Moving-coil, middle relaxation zone and big relaxation zone；
The small relaxation zone refers to 0≤L≤40cm；The middle relaxation zone refers to 40 ＜ L≤150cm, and described is big
Relaxation zone refers to L ＞ 150cm.
D, it is adopted and the lower section described in the extent of the destruction of bottom plate and step b is adopted pair based on the superjacent described in step a
The extent of the destruction of top plate determines the secondary top board structure classification indicators H of dynamic pressure by the dual influence synthesis adoptedG, basis
Formula (8), which calculates, to be obtained：
HG=hmax+L (8)；
I.e. as coal seam spacing hc≤HGWhen, back is considered as secondary top plate mechanical structure；Work as hc＞ HGWhen, then it is considered as original
Raw top plate mechanical structure.
As the preferred embodiment of the present invention, superjacent adopts the destruction to bottom plate, is in master by passive stressed zone
Move what is formed to goaf under the action of dynamic stress area and unfair stress area.
Preferably, when country rock is small relaxation zone, using shotcrete support or nude；When country rock is middle relaxation zone,
Using the supporting of spray-up part or the part supporting of spray-up metal mesh；When country rock is big relaxation zone, locally propped up using spray-up metal mesh
Shield or comprehensive treatment.
Advantageous effects caused by the present invention：
(1) it for the technical barrier that closely inclined seam working from top down is brought, has been put forward for the first time a kind of for multiple seam
The quantitative analysis of the secondary roof overburden structure of exploitation and evaluation method；
(2) it based on Exploring Loose Rock Country in Tunnels theory, detects the plastic zone range of workings subject to dy namic pressure country rock and is classified to it,
The overall stability in objective evaluation tunnel provides theoretical direction and scientific basis for Surrounding Rock Control, supporting optimum etc..
Description of the drawings
The present invention will be further described below in conjunction with the accompanying drawings：
Fig. 1 is the secondary top plate mechanical structure figure of workings subject to dy namic pressure of the present invention；
Fig. 2 is the Mechanical Form figure adopted to Seam Floor Failure；
Fig. 3 is Exploring Loose Rock Country in Tunnels schematic diagram；
Fig. 4 is tunnel ambient stress distribution figure；
Fig. 5 is mechanical model figure.
In figure, 1, superjacent top plate, 2, superjacent goaf, 3, isolation rock stratum, 4, underlying seam, 5, relaxation zone,
6th, plastic zone, 7, elastic region.
In Fig. 1, the distance between l, workings subject to dy namic pressure and secondary top plate；The inclination angle of α, two layers coal；hc, coal seam spacing.
Specific embodiment
The present invention proposes a kind of secondary top board structure quantitative analysis exploited based on inclined seam and its evaluation method, is
Make advantages of the present invention, technical solution clearer, clear and definite, elaborate to the present invention with reference to specific embodiment.
For many technical barriers brought during closely inclined seam working from top down, it is put forward for the first time underlying seam
One kind " secondary top board structure " that tunnel is formed under the influence of repeated mining.Based on this, the analysis secondary top plate of workings subject to dy namic pressure is to enclosing
The adverse effect of rock stability, and then choose rational supporting scheme for science and sufficient technological guidance and theoretical foundation are provided.
First, as shown in Figure 1, the inclination angle of two layers of coal is α, spacing hc, secondary top board structure refers to one above workings subject to dy namic pressure
Set a distance l causes the rock beam superjacent top plate 1 broken to form after being exploited there are superjacent and the superjacent left is adopted
Dead zone 2, the presence in superjacent goaf 2 show lower section strata behavior analysis of roadway influence greatly.It is mainly characterized by superjacent and adopts
In small distance between 4 back of dead zone 2 and underlying seam, rock stratum 3 is isolated between the two to be influenced by dual adopt, and joint is split
Gap is more developed, and isolation rock stratum 3 is substantially at mecystasis；In addition the presence in goaf causes the integrality of rock stratum, horizontal force
Potentiality and natural equilibrium structure of transmission etc. are seriously damaged, spoil, part base object model rock beam and coal in the goaf of top
Column, which shows lower section strata behavior analysis of roadway, to be influenced more violent, and the stability in tunnel is poor, general that apparent deformation occurs, and easily loses
It is steady to destroy.
2nd, the secondary top board structure criterion " H of dynamic pressureG" determine
Top board structure classification indicators " HG" it is destruction to bottom plate to be adopted based on top and (pick lane) is adopted to top plate in lower section
Extent of the destruction, i.e., integrated and determined by the dual influence adopted.
(1) superjacent adopts the destruction to bottom plate
According to existing research：In recovery process, floor rock under the action of branch bearing capacity, according to present position,
Loading characteristic and mobile route form three areas, and I is main dynamic stress area, and II is unfair stress area, and III is passive stressed zone, is such as schemed
Shown in 2.Passive stressed zone moves under the action of active stressed zone and unfair stress area to goaf, forms floor strata and breaks
It is bad.
Gob floor rock stratum maximum plastic failure depth hmaxFor：
In formula：M-mining height, m；K-the factor of stress concentration, k=2；γ-overlying rock volume-weighted average, kN/m3；H-coal
Layer buried depth, m；C-coal seam cohesive force, MPa；φ-coal seam internal friction angle, °；F-coal seam and roof and floor friction coefficient,ξ-triaxial stress coefficient,φf- floor strata internal friction angle, °.
(2) destruction of (pick lane) to top plate is adopted in lower section
Closely inclined seam back rock stratum by it is dual adopt influenced it is bigger, rock strength reduce, joint is split
Gap development is serious, therefore can be approximately ravelly ground.(pick lane) is adopted in lower section can utilize roadway surrounding rock pine to the destruction height of top plate
Moving-coil theory is determined.
Wall rock loosening ring is the important evidence for carrying out improving stability of surrounding rocks in roadway evaluation and carrying out Rational Support Design.It encloses in tunnel
Rock relaxation zone support theory proposes after being furtherd investigate by China Mining University professor Dong Fangting to roadway surrounding rock state.
The study found that the presence of wall rock loosening ring is the intrinsic characteristic in tunnel, its range (thickness value L) is at present using borehole imaging
The instruments such as instrument (Detector for Wall Rock Crack), sonic apparatus or multipoint displacement meter are measured.The main object of roadway support is country rock
The bulking deformation power generated during relaxation zone Emergence and Development, the source that anchor pole bears pulling force are the generation of relaxation zone, hair
Exhibition；And according to the size of wall rock loosening ring thickness value L, be classified as it is small, in, big 3 class, and then obtain corresponding supporting mechanism and
Prioritization scheme.
1. the stress state after roadway excavation
Before roadway excavation, rock mass is in virgin state of stress, causes rock mass internal stress again after roadway excavation
Distribution, force-bearing of surrounding rock mass from three-dimensional become two to and pure stress, rock strength is caused different degrees of reduction occur, is broken
Original original stress equilibrium state is broken, and generates stress concentration.If country rock concentrated stress value is less than the rock characterization after declining
Intensity, then country rock is in elastic-plastic behavior, adjoining rock stability, otherwise country rock will destroy, and this destruction is gradually extended to deep,
Until the three-dimensional stress equilibrium state for reaching new, occurs a loose zone of fracture in country rock at this time, this due to answering
The relaxation zone of fracture that power effect generates is known as wall rock loosening ring, and mechanical characteristics show as stress reduction.Enclosing after roadway excavation
Rock can be divided into loose rupture zone (relaxation zone 5), plastic zone 6 and elastic region 7, as shown in Figure 3.
Relaxation zone is bigger, and surrounding rock failure is more serious, and supporting is more difficult, and the factor for influencing Exploring Loose Rock Country in Tunnels size is main
Have：Surrouding rock stress, rock strength, geological structure, tunnel span, roadway shape, digging time, groundwater effect, construction method,
Support pattern and supporting intensity etc., relaxation zone are an overall targets under above-mentioned various factors collective effect.Rationally really
The size of Exploring Loose Rock Country in Tunnels is determined for evaluation improving stability of surrounding rocks in roadway and supporting effect, optimization drift support type and supporting
Parameter ensures that roadway support safety etc. has great importance.
2. the theory analysis of Exploring Loose Rock Country in Tunnels
Rock mass is after excavating stress redistribution so that the stress distribution feature that secondary stress elastoplasticity occurs and deposits.For
Simplified theory analysis, be approximately considered circular tunnel digging in continuous, homogeneous, isotropism, in the stress of primary rock be P0It is equal
In even stress field, mechanical model is as shown in Figure 4, Figure 5.
When the secondary stress of hole wall exceeds the yield stress of rock mass, then wall rock mass in hole generates plastic zone, and plastic zone is a kind of
State of limit equilibrium, according to Elasticity, the balance differential equation that each point stress is met is：
In plastic zone, since rock mass just starts to destroy, in state of limit equilibrium, each point stress should all meet More-
Coulomb strength criterion：
In formula：The cohesive force of c-country rock, kg/cm2；- internal friction angle, °；σθ- circumference stress, kg/cm2；σr- radially
Stress, kg/cm2；The radius at any point investigated in r-plastic zone, cm.
Formula (2) substitution formula (1) is obtained equation general solution is：
c1For undetermined constant, can be determined according to boundary condition：On tunnel-surrounding, r=r0, σr=Pi(PiIt is stent pair
The counter-force of country rock).By r0And PiSubstitution formula (3)：
Wushu (4) substitutes into formula (2), formula (3) obtains plastic zone stress and is：
Intersection (r=R in elastic region and plastic zone0), stress is continuous, so σrAnd σθBoth it should meet elastic region
Stress distribution law, and the stress distribution law of plastic zone should be met, usually by the distance of this elastic separation to hole axis
Referred to as plastic circle radius r.(5) formula is substituted into the condition σ of elastic stress satisfactionr+σθ=2P0：
It can be obtained by formula (6), the stress of primary rock at the place of tunnel is bigger, and inelastic deformation is just bigger；Stent is to enclosing
The counter-force of rock is bigger, and the radius of inelastic deformation is just smaller, does not have to stent such as, then the radius of inelastic deformation is maximum
Value；Rock strength is smaller, and inelastic deformation is just bigger；Reflect on the area of tunnel to be exactly that tunnel radius is bigger, non-resilient change
Shape area is also bigger.Illustrate Exploring Loose Rock Country in Tunnels and Surrounding Rock Strength, stress size and supporting situation are closely related.
3. the actual measurement and analysis of Exploring Loose Rock Country in Tunnels
This test records country rock in real time using CXK6 type Mine-used I. S borehole imagings instrument (using for reference the prior art)
Image is ruptured to determine the size of workings subject to dy namic pressure wall rock loosening ring.CXK6 type Mine-used I. S borehole imagings instrument is suitable for coal mine
All kinds of drillings detection under lower mal-condition, such as observation anchor shaft anchor cable hole, drawing-off gas hole, forward probe hole, coal seam rock stratum are surveyed
Inspecting hole, geological prospecting hole and wall rock loosening ring etc. can accurately disclose underground engineering wall rock state, can be compared with reference to related analysis software
Accurately speculate the attitude of rocks, cranny development spread scenarios and loose damage range etc., result of detection can be used for coal mine work area
Roof delamination collapse emit, roadway surrounding rock rupture unstability, the disaster forewarning on engineering failure forecast of the undergrounds such as pitshaft failure by rupture；It can also be used for
The parameter designings such as underground engineering suspension roof support, wall rock grouting reinforcing, roadway repair and underground engineering construction quality, supporting scheme are commented
Estimate analysis etc., reliable, authentic and valid field data and analysis are provided for coal mine and geotechnical engineering.
4. Exploring Loose Rock Country in Tunnels is classified
1 Exploring Loose Rock Country in Tunnels classification chart of table
The purpose of rocvk classification is correctly to evaluate supporting difficulty, distinguishes main Supporting Object, propped up so as to reasonably determining
Parameter and construction technology are protected, foundation is provided for similar roadway support design.Wall rock loosening ring size had both included influencing adjoining rock stability
The factors of property, and reflect the interaction result of factors, it is a comprehensive classification indicators.Use wall rock loosening
Circle classification country rock has following outstanding advantages：
A. the difficult problems such as the stress of primary rock, Surrounding Rock Strength, structure surface properties measure have been bypassed, but have caught them emphatically
Influence as a result, i.e. relaxation zone is an overall target for including multifactor impact；
B. obtained by relaxation zone system field measurement, any hypothesis is not made in importance；
C. after relaxation zone size is by surveying acquisition, intuitively simple during supporting parameter, field application convenience is determined；
D. single integrated index classification is used, repeatability, the reliability of classification be not different with the experience of people difference；
E. the theory of relaxation zone sorting technique and practical basis are more solid, and technology system is formd with Design of bolt support
Row.
With reference to bolt-spary supports mechanism, according to Roadway Support Theory Based On Broken Rock Zone, the size L according to relaxation zone divides country rock
150) and big relaxation zone for small relaxation zone (0~40cm, including endpoint value), middle relaxation zone (40~150cm, not including 40, including
(being more than 150cm) six groups of three categories, are shown in Table 1.
In summary analysis is it is found that the prediction standard of secondary roof overburden structure is HG=hmax+L.I.e. as coal seam spacing hc
≤HGWhen, back is considered as secondary top plate mechanical structure；Work as hc＞ HGWhen, then it is considered as primary top plate mechanical structure.
It should be noted that：The simple replacement that those skilled in the art do these terms under the enlightenment of the present invention,
It should all be within protection scope of the present invention.
Claims (3)
1. a kind of secondary top board structure quantitative analysis and its evaluation method based on inclined seam exploitation, which is characterized in that successively
Include the following steps：
A, determine that superjacent adopts the extent of the destruction to bottom plate, i.e. gob floor rock stratum maximum plastic failure depth hmax, lead to
Cross formula (1) calculating：
In formula (1), M-mining height, m；K-the factor of stress concentration, k=2；γ-overlying rock volume-weighted average, kN/m3；H-coal seam
Buried depth, m；C-coal seam cohesive force, MPa；φ-coal seam internal friction angle, °；F-coal seam and roof and floor friction coefficient,
ξ-triaxial stress coefficient,φf- floor strata internal friction angle, °；
B, determine that the extent of the destruction to top plate is adopted in lower section, i.e. the destruction height to top plate is adopted in lower section, utilizes roadway surrounding rock pine
Moving-coil theory determines, is divided into following sub-step：
B1, the country rock after roadway excavation is divided into relaxation zone, plastic zone and elastic region；
B2, the theory analysis for carrying out Exploring Loose Rock Country in Tunnels：
Rock mass is after excavating stress redistribution so that the stress distribution feature that secondary stress elastoplasticity occurs and deposits, for letter
Change theory analysis, it is believed that circular tunnel digging is P in continuous, homogeneous, isotropism, in the stress of primary rock0Uniform stress field
In, when the secondary stress of hole wall exceeds the yield stress of rock mass, then wall rock mass in hole generates plastic zone, and plastic zone is that a kind of limit is put down
Weighing apparatus state, according to Elasticity, shown in the balance differential equation such as formula (2) that each point stress is met：
In formula (2), σθ- circumference stress, kg/cm2；σr- radial stress, kg/cm2；Any point investigated in r-plastic zone
Radius, cm；
B3, in plastic zone, since rock mass just starts to destroy, in state of limit equilibrium, each point stress should all meet More-
Coulomb strength criterion, as shown in formula (3)：
In formula：The cohesive force of c-country rock, kg/cm2；- internal friction angle, °；σθ- circumference stress, kg/cm2；σr- radially should
Power, kg/cm2；The radius at any point investigated in r-plastic zone, cm；
Formula (3) is substituted into formula (2) to obtain shown in equation general solution such as formula (4)：
c1For undetermined constant, determined according to boundary condition：On tunnel-surrounding, r=r0, σr=Pi；PiIt is stent to country rock
Counter-force；
By r0And PiSubstitution formula (4) obtains formula (5)：
B4, formula (5) substitution formula (3), (4) are obtained shown in plastic zone stress such as formula (6)：
B5, formula (6) is substituted into the condition σ that elastic stress meetsr+σθ=2P0Obtain formula (7)：
C, Exploring Loose Rock Country in Tunnels surveyed, analyzed, country rock is divided into small loosening according further to the size L of relaxation zone
Circle, middle relaxation zone and big relaxation zone；
The small relaxation zone refers to 0≤L≤40cm；The middle relaxation zone refers to 40 ＜ L≤150cm, the big loosening
Circle refers to L ＞ 150cm；
D, it is adopted based on the superjacent described in step a and the lower section described in the extent of the destruction of bottom plate and step b is adopted to top plate
Extent of the destruction, that is, pass through the dual influence synthesis adopted and determine dynamic pressure secondary top board structure classification indicators HG, according to formula (8)
It calculates and obtains：
HG=hmax+L (8)；
I.e. as coal seam spacing hc≤HGWhen, back is considered as secondary top plate mechanical structure；Work as hc＞ HGWhen, then it is considered as primary top plate
Mechanical structure.
2. secondary top board structure quantitative analysis and its evaluation method according to claim 1 based on inclined seam exploitation,
It is characterized in that：Superjacent adopts the destruction to bottom plate, is in active stressed zone and unfair stress area by passive stressed zone
Move what is formed to goaf under effect.
3. secondary top board structure quantitative analysis and its evaluation method according to claim 1 based on inclined seam exploitation,
It is characterized in that：When country rock is small relaxation zone, using shotcrete support or nude；When country rock is middle relaxation zone, use
The supporting of spray-up part or the part supporting of spray-up metal mesh；When country rock is big relaxation zone, using the part supporting of spray-up metal mesh or
Comprehensive treatment.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110610043A (en) * | 2019-09-10 | 2019-12-24 | 辽宁工程技术大学 | Method for calculating damage depth of inclined coal seam goaf bottom plate |
| CN111608707A (en) * | 2020-04-29 | 2020-09-01 | 临沂矿业集团菏泽煤电有限公司 | Rock burst dangerous roadway support method based on double-cylinder protection theory |
| CN111608663A (en) * | 2020-04-29 | 2020-09-01 | 临沂矿业集团菏泽煤电有限公司 | Omnibearing pressure relief method for rock burst dangerous roadway of thick coal seam working face |
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