CN105241510B - The assay method of tunnel surrounding prestressed reinforcement rock-bolt length and radial direction prestress value - Google Patents
The assay method of tunnel surrounding prestressed reinforcement rock-bolt length and radial direction prestress value Download PDFInfo
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Abstract
The invention discloses tunnel surrounding prestressed reinforcement rock-bolt length and the assay method of radial direction prestress value, according to country rock elastic plastic theory and Plastic Zone Distribution rule, on the basis of comprehensive determination tunnel plastic circle radius R and pressure from surrounding rock, determine that tunnel surrounding reinforces anchor pole minimum length and radially minimum prestress value.The beneficial effects of the invention are as follows：According to country rock elastic plastic theory and Plastic Zone Distribution rule, on the basis of comprehensive determination tunnel plastic circle radius R and pressure from surrounding rock, determine that tunnel surrounding reinforces anchor pole minimum length and radially minimum prestress value, calculating process definitely, it is terse, the result accuracy surveyed is higher, it is more accurate, it is smaller with actual error, can preferably Guiding Practice.
Description
Technical field
The present invention relates to tunnel surrounding stress determination and Analyses of Tunnel Wall Rock Stability is evaluated and liner support reinforcement design side
Method field, and in particular to the assay method of tunnel surrounding prestressed reinforcement rock-bolt length and radial direction prestress value.
Background technology
In recent years, with increasing Tunnel Engineering construction, China is in infrastructure such as traffic, water conservancy and hydropower, municipal administrations
Field achieves the achievement to attract people's attention, particularly nearly ten years, more achieves the development advanced by leaps and bounds, while in underground engineering
Design and construction technique level there has also been large increase.
Currently in order to keeping the use headroom of tunnel cave section, the various loads being likely to occur are born, ensure tunnel cave country rock
Stable and security, usually need to set supporting construction during tunnel excavation.Support structure design for a long time often uses steel
Yoke and concrete lining, although with sufficiently large rigidity and cross dimensions, the intensity of itself is completely dependent on, passive
The powerful broken-rock pressure of country rock is born to maintain the stabilization of chamber so that using these traditional supportings although spending substantial amounts of work
Journey expense, preferable Expected Results is but extremely difficult to, simultaneously because its slow, structure of construction and country rock phase separation etc. are intrinsic weak
Point, the destruction of supporting construction and the slump of country rock are often what is be difficult to avoid that.With the popularization of New Austrian Tunneling Method, we, which can be found that, encloses
The appropriateness deformation of rock has certain benefit for the resistance to overturning of tunnel structure, so in the construction of modern tunnel, shotcrete
Supporting can carry out supporting in time as one kind, limit country rock excessive deformation and loosen, and it is certain that and can allows country rock to occur
Deformation, the new support pattern for the features such as making full use of surrouding rock deformation and increasing the stability in tunnel, have started to extensive
It is applied to modern tunnel support conceptual design.The support pattern for the main use that bolt-spary supports is constructed as New Austrian Tunneling Method, its
Function is the important component for promoting country rock to be changed into supporting construction from load thing, plays making certainly for country rock to greatest extent
With safeguarding the stabilization of chamber with less supporting drag.
The general design method of bolt-spary supports includes following several method at present：(1) engineering analog method.This method is mainly
It is directly true with reference to the experience of built engineering according to country rock grade and tunnel specification on the basis of classifying to country rock
Determine shotcrete parameter and construction method；(2) information design method.This design method be using live measured information as design considerations, its
The characteristics of maximum is while the result of measurement is fed back in design and construction, to make plan while carry out various measurements in construction
When design, construction become to more conform to live actual, finally determine supporting parameter；(3) theoretical calculation.This method is to survey
On the premise of obtaining rock mass and supporting mechanics parameter, according to coffer mechanics feature founding mathematical models, pass through and calculate determination supporting ginseng
Several methods.This method is the development based on rock mass mechanics, considers country rock and supporting collective effect and gradually forms and develop
Get up.Its specific mechanical model and computational methods currently have approximate mainly depending on rock mass attribute and structure type
Analytical algorithm and by means of numerical solutions such as the finite element of computer, boundary elements.Though above-mentioned Forecasting Methodology is general in bolt-spary supports
Design in played important function, but process is established by analyze above-mentioned design method, it can be found that the above method is present
The deficiency of following several respects：Engineering analog method is with the data that information design method mainly measures using practical experience or actually as design
Foundation, but often influenceed by objective practice condition, measurement accuracy, measuring method and survey tool, and cause it in reality
Border use on larger error be present, while lack theoretical calculation according to and so that the above method really can not be effectively used in
In engineering construction；Although theoretical calculation development is ripe, what is used is this computational methods and few, this be mainly because
Changeable for wall rock geology complex, its mechanical model and Mechanics Parameters of Rock Mass are not easy accurate test and determined, so typically only
As a calculation means in design, mutually checked with other design methods.
Being analyzed more than to obtain, and the design both at home and abroad for underground chamber bolt-spary supports form at present does not have complete set
Theoretical calculation system, existing theoretical calculation method and be difficult effectively accurately be applied to support structure design, therefore,
The present invention determines tunnel plastic circle radius R and pressure from surrounding rock according to country rock elastic plastic theory and Plastic Zone Distribution rule comprehensive
On the basis of, determine that tunnel surrounding reinforces anchor pole minimum length and radially minimum prestress value.
The content of the invention
The shortcomings that in above-mentioned traditional underground chamber liner Design Method of Reinforcing and deficiency, according to country rock elastic plastic theory
And Plastic Zone Distribution rule, circular tunnel pressure from surrounding rock and plastic circle radius are studied and determine, and it is basic according to above-mentioned two
Anchor pole minimum length and radially minimum reinforcing prestress value are reinforced in parametric synthesis determination, are ensureing circular tunnel stabilization to reach
Under the premise of more save engineering cost with shortening the purpose of construction period, there is good practical valency in subterranean tunnel reinforcing engineering
Value.
In order to reach above-mentioned purpose, the present invention adopts the following technical scheme that：
The assay method of tunnel surrounding prestressed reinforcement rock-bolt length and radial direction prestress value, including：
The first step：Determine the natural stress of Rock Mass；
Second step：Determine the physical and mechanical parameter of Rock Mass；
3rd step：Tunnel surrounding section plastic circle radius is determined according to the natural stress and physical and mechanical parameter of rock mass；
4th step：According to the natural stress of rock mass, physical and mechanical parameter, tunnel excavation radius of circle and tunnel plastic circle radius
Determine Tunnel Surrounding Rock Pressure；
5th step：The horizontal spacing and longitudinal pitch of Tunnel Surrounding Rock Pressure, adjacent anchor pole in the 4th step determine tunnel
Road reinforces anchor pole radial direction prestress value；
6th step：The optimal design length of tunnel reinforcement anchor pole is determined according to anchor rod anchored section of optimization length.
Further, the natural stress σ of Rock Mass is determined in the first step using drilling set core stress contact methodZ,
Comprise the following steps that：
1) at tunnel surrounding reconnaissance, drill and beat measured hole in bottom hole；
2) strain gauge is loaded in measured hole, strain gauge is connected with deformeter；
3) deformeter record initial reading, contact stress is bored by covering, record strain-ga(u)ge reading Ua、Ub、UcUntil stress is complete
Complete solution removes；
4) fracture core, is tried to achieve according to formula (1)
In formula：σ1Maximum principal stress in-cell cube, σ3Minimum principal stress in-cell cube, the compression strength of E-rock；
R*The radius of-measured hole；Ua、Ub、UcShift value measured by-deformeter a, b, c；2 θ-determined according to tan2 θ calculated values；
5) the natural stress σ of rock mass is tried to achieve according to formula (6)Z：
Further, the physical and mechanical parameter of country rock includes country rock internal friction angle parameter in the second stepInterior friction
Angular dimensions is equal to the reduction coefficient that sillar internal friction angle standard value is multiplied by setting, and reduction coefficient determines according to cranny development degree,
(crack agensis, crack are relatively developed, cranny development, and reduction coefficient corresponding to cataclastic texture is 0.90~0.95,0.85 respectively~
0.90,0.80~0.85,0.75~0.80).
Further, the physical and mechanical parameter of country rock includes country rock internal cohesion parameter c, internal cohesion in the second step
Parameter is multiplied by the reduction coefficient of setting by country rock internal cohesion standard value, and reduction coefficient is 0.2~0.3.
Further, tunnel surrounding section plastic circle radius R obtains according to formula (3) in the 3rd step：
In formula：R-tunnel plastic circle radius；Ro- relaxation zone radius (takes Ro=r).
Further, Tunnel Surrounding Rock Pressure σ is tried to achieve according to formula (4) in the 4th stepw：
In formula：R-tunnel excavation radius of circle.
Further, in the 5th step, according to ground anchorage and concrete spraying support engineering legislation, between anchor pole
Away from not be preferably greater than rock-bolt length 1/2, when wall rock condition is poor, crustal stress is higher or adit digging size is larger, anchor pole cloth
Putting spacing should suitably encrypt.For the suitable 0.50m~1.00m of anchor pole spacing in IV, V grade of country rock, and it is true to cannot be greater than 1.25m
The horizontal spacing of fixed adjacent two anchor poleAnd longitudinal pitch Sb。
Further, in the 5th step, tried to achieve according to formula (5) and reinforce anchor pole radial direction prestress value fy：
Further, according to ground anchorage and concrete spraying support engineering legislation, anchor pole is calculated by formula (6)
The optimization length Δ l of anchoring section：
In formula：D-anchorage body diameter；fmsUltimate bond stress between-anchoring body surface and surrounding Rock And Soil；
η-anchoring body bonds safety coefficient；The radical of n-reinforcing bar or steel strand wires；The adhesion strength at ξ-interface reduces coefficient, takes 0.7-
0.85；Influence coefficient of the ψ-anchoring strength to adhesion strength.
Further, in the 6th step, tunnel reinforcement anchor pole optimal design length L calculates according to formula (7)：
L=R-r+ Δs l (7).
In above formula (7), R-r is exactly the length of free section.
The present invention operation principle be：
Circular tunnel plastic circle radius refers to that country rock is plastically deformed and the boundary point of elastic deformation to the circular tunnel center of circle
Distance.The determination of plastically deforming area and elastic deformation area's boundary point is related to the determination of suspension roof support anchoring section initial point position,
So the determination of plastic circle radius is related to the determination of whole combined bolting and shotcrete design parameter.And the sarifying section of surrounding rock is top layer after excavating
Country rock gradually extends with the generation of displacement with development, destruction to depths, the part rock for being destroyed its continuity and integrality
Stone region, because sarifying section of surrounding rock radius is directly connected to the safety of Tunnel Engineering, so strictly to control country rock not produce pine
Dynamic area, i.e. Ro=r.
1. use elastic and plastic properties theoretical calculation pressure from surrounding rock, it is assumed that a horizontal circle is excavated in natural stress field rock mass
Tunnel cave, caused surrouding rock stress τ=0, then σb、σθIt is principal stress.According to mole-coulomb strength condition as country rock
The condition of palsticity, then when country rock produces plastic zone, there is the redistribution figure (such as Fig. 5) of stress behind plastic zone, in its plastic zone
Stress σbAnd σθFollowing formula will be met：
I.e. all regions for meeting above formula will all produce plastic deformation, plastic circle occurs.If geologic feature is neglected to enclosing
The influence of rock stress distribution, because surrouding rock stress distribution is axisymmetric, therefore plastic circle is also axisymmetric.The rock in plastic circle
The cohesive force c of stone, internal friction angleIt will be reduced with elastic modulus E.The ungratified region of stress, it is still elasticity in country rock
Deformed area.Its stress-strain relation still obeys Hooke's law.In plastic zone, the equilibrium condition that every bit stress must meet is i.e.：
The stress of plastic zone can be tried to achieve by above-mentioned formula (9)：
From above formula, the stress σ of plastic zoneb、σθOnly it is radius vector b function, it changes with b change.In plastic zone
Tangential stress σθReduce a lot, the degree of reduction is relevant with the size being plastically deformed, and plastic deformation is maximum on cave wall, therefore σθDrop
Low is most, but and is not zero.Because rock also has certain bearing capacity after generating plastic deformation.In answering for elastic region
Power but slightly raises, and this is due to a part of stress release in plastic zone, and a part of stress then imputes to the knot of elastic region
Fruit.
The stress of elastic region is calculated as follows：
In formula：
The radius vector of b-calculating point；
σRThe borderline radial stress in-elastic and plastic properties area (can be regarded as active force of the plastic circle to elastic ring)；
The radius of R-plastic circle；
σbThe radial stress of-rock mass
σθThe tangential stress of-rock mass.
For bullet, the modeling borderline any unit in area, it had both belonged to elastic region unit, belonged to plastic zone unit again, thus
The unit should meet the condition that above-mentioned plastic zone and elastic region unit should meet simultaneously.(the r=i.e. on elastic and plastic properties area border
R formula (14)) below is set up：
(σb+σθ)Bullet=(σb+σθ)Modeling (14)
The plastic zone radius R under the conditions of non-support is can obtain by above formula (14)：
The radius of plastic zone is maximum in this case.
If wanting to make plastic region not formed, be i.e. during R=r, obtained by pressure from surrounding rock formula (see principle 2) and do not form plastic zone
Required Support Resistance：
The maximum Support Resistance needed for elastic stress field is in here it is tunnel is maintained.Its size only with primary stress field
And lithological indicators are relevant, and it is unrelated with tunnel size.Above formula σwIt is actually consistent with the stress expression formula on Elastic-Plastic Boundary, say
Bright Support Resistance can change the stress in the size and plastic zone of plastic zone, and can not change the stress of Elastic-Plastic Boundary.It is actual
Upper supporting is built after tunnel excavation in certain time, plastic region and its deformation occurrence and development.Needed for therefore
The numerical value that Support Resistance will be determined less than above formula.
According to our definition to relaxation zone, i.e. the borderline tangential stress of relaxation zone is primary stress, i.e. στ=σz, can
：
Relaxation zone radius can be obtained：
It can be seen that there is certain relation in relaxation zone radius and plastic zone radius.
2. pressure from surrounding rock refers to cause underground excavation spatial peripheral rock mass and Support Deformation or the active force of destruction.With new
The flexible support forms such as extensive use of the method difficult to understand in constructing tunnel, bolt-spary supports use it is also more and more, pressure from surrounding rock
Result of calculation necessarily determines that the formal character of supporting construction, parameter are chosen.The present invention is carried out using following pressure from surrounding rock principle
Pressure from surrounding rock calculates：
As R=b, σb=σR, obtained by calculus principle solving plastic zone mechanical equilibrium condition formula：
By：
Then：
The borderline radial stress σ in elastic and plastic properties area can be tried to achieveRFor：
In derivation, consider the influence of cohesive force c on Elastic-Plastic Boundary, can obtain：
When making r=b, σr=σw, then above formula be changed into：
Above formula is pressure from surrounding rock solution formula.σ in formulawTo act on the interior pressure on cave wall, can be regarded as here
Supporting construction is to the active force of country rock, and its numerical value is equal to shoulder bed effects in the power in supporting construction, therefore σwFor required country rock pressure
Power.The size of its pressure from surrounding rock is except the natural stress σ with rock massz, country rock intensive parameter c,And the size of tunnel cave is relevant
Outside, also controlled by the size of plastic zone, its change into opposite with the size of plastic zone radius.When R is maximum, country rock
Pressure σwFor minimum.When not allowing plastic zone occur.Even during R=r, pressure from surrounding rock σwFor maximum, its value can substitute into R=r,
Try to achieve：
The beneficial effects of the invention are as follows：
1) according to country rock elastic plastic theory and Plastic Zone Distribution rule, tunnel plastic circle radius R and country rock are determined comprehensive
On pressure-based, determine that tunnel surrounding reinforces anchor pole minimum length and radially minimum prestress value, calculating process definitely, letter
Practice, the result accuracy surveyed is more accurate, smaller with actual error.
2) according to knowable to calculating, rock-bolt length obtained by assay method of the invention has higher accuracy, for circle
Tunnel Rock Bolt protection has preferable practical value.
Brief description of the drawings
Fig. 1 is flow chart of the present invention；
Fig. 2 is the horizontally disposed figure of measured hole deformeter；
Fig. 3 is anchor pole interplanar spacing schematic diagram；
Fig. 4 is anchor pole section layout drawing；
Fig. 5 is the redistribution figure for occurring stress behind plastic zone.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Whole description.
The method that the present invention is now illustrated by taking certain circular tunnel engineering as an example is used as optimum embodiment.Utilize this method
The design of bolt-spary supports structural anchor bar length optimization is carried out to the circular tunnel engineering.Specific implementation step is as follows：
Step 1：The natural stress σ of tunnel surroundingZDetermination
The natural stress σ of rock massZRefer to the stress being present in before Human dried bloodstains in rock mass, according to tunnel excavation section
Radius r and edpth of tunnel and Rock Mass property, the natural stress σ of synthesis measuring tunnel surrounding rock massZWith physical and mechanical parameterThe circular tunnel depth is about 100m, excavates chamber radius r=3m, country rock severe γ=18kN/m3。
(1) the natural stress σ of this circular tunnel engineering rock masszFor：
According to record strain-ga(u)ge reading Ua=14.8, Ub=13.0, Uc=8.5, and the E=of rock is asked for indoors
47.90, measurement pore radius R*=130.Under the conditions of strain gauge is using mutual placement at 45 °, then σ1、σ3It can be asked by formula once
Solution：
The natural stress σ of rock mass that can then askZFor：
Step 2：Physical and mechanical parameterIt is determined that：
Rock mass physical physical and mechanical parameter can determine that according to experimental dataFor：Internal friction angleIt is interior viscous
Poly- power c=0.2MPa
Step 3：The determination of tunnel surrounding section plastic circle radius
Circular tunnel plastic circle radius refers to that country rock is plastically deformed and the boundary point of elastic deformation to the circular tunnel center of circle
Distance.Circular tunnel plastic circle radius R is calculated using (formula 3)：
This circular tunnel engineering plasticity circle radius R is：
R=3.67m
Step 4：The determination of circular tunnel pressure from surrounding rock
Pressure from surrounding rock refers to cause underground excavation spatial peripheral rock mass and Support Deformation or the active force of destruction, the present invention to adopt
Pressure from surrounding rock σ is determined with below equationWSize.
Step 5：Reinforce the determination of anchor pole radial direction prestress value
1) the transverse direction and longitudinal direction spacing of anchor poleSbIt must determine
By《Ground anchorage and concrete spraying support engineering legislation》In GB50086-2011 the 7.3.2.2 articles can
Know, anchor pole spacing is not preferably greater than the 1/2 of rock-bolt length.When wall rock condition is poor, crustal stress is higher or adit digging size is larger
When, anchor pole arrangement spacing should be encrypted suitably.For the suitable 0.50m~1.00m of anchor pole spacing in IV, V grade of country rock, and must not be big
In 1.25m.The spacing of anchor pole is can determine that according to above-mentioned regulation and engineering experienceSb=0.8m.
2) determination of anchor pole radial direction prestress value is reinforced
The supporting reaction provided according to hypothesis suspension roof support structure tunnel cave wall is generally evenly distributed in the model of support action
In enclosing, then the anchor rod prestress power to be balanced is pressure from surrounding rock sum in the sphere of action of this anchor pole.Can be in the hope of every
The limit pre-stress design value f provided needed for root anchor poley：
Step 6：The determination of rock-bolt length in combined bolting and shotcrete
1) determination of anchor rod anchored length
According to《Ground anchorage and concrete spraying support engineering legislation》The 4.6.11 articles of GB50086-2011 takes anchor
It is 1.6 that solid, which bonds safety coefficient K, the ultimate bond stress f between anchoring body surface and surrounding soilms=1000KPa, ξ=
0.85, ψ=1.6, anchor rod body diameter is selectedReinforcing bar.Try to achieve Δ l：
2) in bolt-spary supports rock-bolt length determination
Anchor pole free end length：
Δ L=R-r=3.67m-3.0m=0.67m
Rock-bolt length in bolt-spary supports：
L=R-r+ Δs l=3.67m-3.0m+4.08m=4.75m
Described above is only the preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, under the premise without departing from the principles of the invention, some improvements and modifications can also be made, these improvements and modifications also should
It is considered as protection scope of the present invention.
Claims (10)
1. the assay method of tunnel surrounding prestressed reinforcement rock-bolt length and radial direction prestress value, it is characterised in that including：
The first step：Determine the natural stress of Rock Mass；
Second step：Determine the physical and mechanical parameter of Rock Mass；
3rd step：Tunnel surrounding section plastic circle radius is determined according to the natural stress and physical and mechanical parameter of rock mass；
4th step：Determined according to the natural stress of rock mass, physical and mechanical parameter, tunnel excavation radius of circle and tunnel plastic circle radius
Tunnel Surrounding Rock Pressure；
5th step：The horizontal spacing and longitudinal pitch of Tunnel Surrounding Rock Pressure, adjacent anchor pole in the 4th step determine that tunnel adds
Gu anchor pole radial direction prestress value；
6th step：The optimal design length of tunnel reinforcement anchor pole is determined according to anchor rod anchored section of optimization length.
2. assay method as claimed in claim 1, it is characterised in that using drilling set core stress contact method in the first step
Determine the natural stress σ of Rock MassZ, comprise the following steps that：
1) at tunnel surrounding reconnaissance, drill and beat measured hole in bottom hole；
2) strain gauge is loaded in measured hole, strain gauge is connected with deformeter；
3) deformeter record initial reading, contact stress is bored by covering, record strain-ga(u)ge reading Ua、Ub、UcUntil stress solves completely
Remove；
4) fracture core, is tried to achieve according to formula (1)
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<mi>U</mi>
<mi>c</mi>
</msub>
</mrow>
<mrow>
<msub>
<mi>U</mi>
<mi>a</mi>
</msub>
<mo>-</mo>
<msub>
<mi>U</mi>
<mi>c</mi>
</msub>
</mrow>
</mfrac>
</mrow>
</mtd>
</mtr>
</mtable>
</mfenced>
<mo>-</mo>
<mo>-</mo>
<mo>-</mo>
<mrow>
<mo>(</mo>
<mn>1</mn>
<mo>)</mo>
</mrow>
</mrow>
In formula：σ1Maximum principal stress in-cell cube, σ3Minimum principal stress in-cell cube, the compression strength of E-rock；R*—
The radius of measured hole；Ua、Ub、UcShift value measured by-deformeter a, b, c；2 θ-determined according to tan2 θ calculated values；
5) the natural stress σ of rock mass is tried to achieve according to formula (2)Z：
<mrow>
<msub>
<mi>&sigma;</mi>
<mi>z</mi>
</msub>
<mo>=</mo>
<mfrac>
<mn>1</mn>
<mn>2</mn>
</mfrac>
<mrow>
<mo>(</mo>
<msub>
<mi>&sigma;</mi>
<mn>1</mn>
</msub>
<mo>+</mo>
<msub>
<mi>&sigma;</mi>
<mn>3</mn>
</msub>
<mo>)</mo>
</mrow>
<mo>+</mo>
<mfrac>
<mn>1</mn>
<mn>2</mn>
</mfrac>
<mrow>
<mo>(</mo>
<msub>
<mi>&sigma;</mi>
<mn>1</mn>
</msub>
<mo>-</mo>
<msub>
<mi>&sigma;</mi>
<mn>3</mn>
</msub>
<mo>)</mo>
</mrow>
<mi>c</mi>
<mi>o</mi>
<mi>s</mi>
<mn>2</mn>
<mi>&theta;</mi>
<mo>-</mo>
<mo>-</mo>
<mo>-</mo>
<mrow>
<mo>(</mo>
<mn>2</mn>
<mo>)</mo>
</mrow>
<mo>.</mo>
</mrow>
3. assay method as claimed in claim 1, it is characterised in that the physical and mechanical parameter of country rock includes in the second step
Country rock internal friction angle parameterInternal friction angle parameter is equal to the reduction coefficient that sillar internal friction angle standard value is multiplied by setting, reduction system
It is several to be determined according to cranny development degree.
4. assay method as claimed in claim 1, it is characterised in that the physical and mechanical parameter of country rock includes in the second step
Country rock internal cohesion parameter c, internal cohesion parameter are multiplied by the reduction coefficient of setting by country rock internal cohesion standard value.
5. assay method as claimed in claim 1, it is characterised in that tunnel surrounding section plastic circle radius in the 3rd step
R obtains according to formula (3)：
In formula：R-tunnel plastic circle radius；Ro- relaxation zone radius, takes Ro=r, r-tunnel excavation radius of circle,In-country rock
Rub angular dimensions.
6. assay method as claimed in claim 5, it is characterised in that tunnel is tried to achieve according to formula (4) in the 4th step and enclosed
Rock pressure power σw：
In formula：R-tunnel excavation radius of circle, σZThe natural stress of-Rock Mass, c-country rock internal cohesion parameter.
7. assay method as claimed in claim 1, it is characterised in that mixed with injection according to ground anchorage in the 5th step
Native support engineering technical specification is coagulated, for the suitable 0.50m~1.00m of anchor pole spacing in IV, V grade of country rock, and cannot be greater than
1.25m, determine the horizontal spacing of adjacent two anchor poleAnd longitudinal pitch Sb。
8. the assay method as described in claim 1 or 7, it is characterised in that in the 5th step, tried to achieve and added according to formula (5)
Gu anchor pole radial direction prestress value fy：
σw- Tunnel Surrounding Rock Pressure,The horizontal spacing of-adjacent two anchor pole, SbThe longitudinal pitch of-adjacent two anchor pole.
9. assay method as claimed in claim 8, it is characterised in that mixed with injection according to ground anchorage in the 6th step
Native support engineering technical specification is coagulated, anchor rod anchored section of optimization length Δ l is calculated by formula (6)：
<mrow>
<mi>&Delta;</mi>
<mi>l</mi>
<mo>=</mo>
<mfrac>
<mrow>
<msub>
<mi>Kf</mi>
<mi>y</mi>
</msub>
</mrow>
<mrow>
<msub>
<mi>n&pi;d&xi;f</mi>
<mrow>
<mi>m</mi>
<mi>s</mi>
</mrow>
</msub>
<mi>&psi;</mi>
</mrow>
</mfrac>
<mo>-</mo>
<mo>-</mo>
<mo>-</mo>
<mrow>
<mo>(</mo>
<mn>6</mn>
<mo>)</mo>
</mrow>
</mrow>
In formula：D-anchorage body diameter；fmsUltimate bond stress between-anchoring body surface and surrounding Rock And Soil；K-anchor
Solid bonds safety coefficient；The radical of n-reinforcing bar or steel strand wires；The adhesion strength at ξ-interface reduces coefficient, takes 0.7-0.85；
Influence coefficient of the ψ-anchoring strength to adhesion strength.
10. the assay method as described in claim 1 or 9, it is characterised in that in the 6th step, tunnel reinforcement anchor pole is most
Excellent design length L is calculated according to formula (7)：
L=R-r+ Δs l (7)
Wherein, R-tunnel plastic circle radius；R-tunnel excavation radius of circle, anchor rod anchored section of optimization length Δ l.
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| CN107587891A (en) * | 2017-08-07 | 2018-01-16 | 宁夏建设职业技术学院 | A kind of coal mine roadway Design of bolt support method |
| CN108062436A (en) * | 2017-12-04 | 2018-05-22 | 中国能源建设集团广东省电力设计研究院有限公司 | The pull out force detection method and system of rock-bolt |
| CN108062439A (en) * | 2017-12-08 | 2018-05-22 | 西安科技大学 | Roadway support quantifying design method based on plastic zone of surrounding rock size |
| CN108005697B (en) * | 2017-12-29 | 2020-08-11 | 中铁第四勘察设计院集团有限公司 | Tunnel system anchor rod design method based on safety coefficient method |
| CN108222969B (en) * | 2017-12-29 | 2019-11-05 | 中铁第四勘察设计院集团有限公司 | A kind of Design of Tunnel method based on method of safety coefficients |
| CN109883779A (en) * | 2019-01-21 | 2019-06-14 | 绍兴文理学院 | Anchor structure face dimensional effect shearing test design method |
| CN109914242B (en) * | 2019-03-18 | 2020-12-15 | 中国石油天然气集团有限公司 | Method for anchoring main cable of combined tunnel anchor type large-span suspension cable pipeline bridge |
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| CN103195453B (en) * | 2013-04-16 | 2015-04-29 | 中国矿业大学 | Parameter determination method for bolt supporting based on roadway bearing structure |
| CN104653196B (en) * | 2015-01-30 | 2017-02-01 | 北京交通大学 | Initial design method of tunnel engineering considering all-parameter influence |
| CN104899421A (en) * | 2015-05-05 | 2015-09-09 | 兖州煤业股份有限公司 | Roadway support parameter determining method and supporting method |
| CN104988918B (en) * | 2015-07-24 | 2016-08-24 | 青岛理工大学 | A kind of assay method of deep basal pit prestressed anchor optimum anchorage length |
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