CN111159949B - Calculation method and system for small clear distance tunnel excavation damaged area - Google Patents
Calculation method and system for small clear distance tunnel excavation damaged area Download PDFInfo
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- 238000009412 basement excavation Methods 0.000 title claims abstract description 31
- 238000004364 calculation method Methods 0.000 title claims description 24
- 230000006378 damage Effects 0.000 claims abstract description 179
- 238000005422 blasting Methods 0.000 claims abstract description 113
- 239000011435 rock Substances 0.000 claims abstract description 102
- 238000012544 monitoring process Methods 0.000 claims abstract description 34
- 238000000034 method Methods 0.000 claims abstract description 31
- 230000008878 coupling Effects 0.000 claims abstract description 30
- 238000010168 coupling process Methods 0.000 claims abstract description 30
- 238000005859 coupling reaction Methods 0.000 claims abstract description 30
- 238000006073 displacement reaction Methods 0.000 claims abstract description 17
- 238000011156 evaluation Methods 0.000 claims abstract description 12
- 230000014509 gene expression Effects 0.000 claims description 28
- 239000000463 material Substances 0.000 claims description 18
- 238000012360 testing method Methods 0.000 claims description 13
- 230000008569 process Effects 0.000 claims description 8
- 230000002706 hydrostatic effect Effects 0.000 claims description 6
- 230000006735 deficit Effects 0.000 claims description 5
- 208000027418 Wounds and injury Diseases 0.000 claims description 3
- 208000014674 injury Diseases 0.000 claims description 3
- 238000013467 fragmentation Methods 0.000 claims description 2
- 238000006062 fragmentation reaction Methods 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 18
- 125000004122 cyclic group Chemical group 0.000 abstract description 11
- 230000009471 action Effects 0.000 abstract description 7
- 238000013461 design Methods 0.000 abstract description 4
- 238000011161 development Methods 0.000 description 5
- 238000004458 analytical method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000005553 drilling Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 102100021503 ATP-binding cassette sub-family B member 6 Human genes 0.000 description 1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/045—Analysing solids by imparting shocks to the workpiece and detecting the vibrations or the acoustic waves caused by the shocks
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/07—Analysing solids by measuring propagation velocity or propagation time of acoustic waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
- G01N29/4409—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison
- G01N29/4418—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison with a model, e.g. best-fit, regression analysis
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/0289—Internal structure, e.g. defects, grain size, texture
Abstract
The embodiment of the invention discloses a method and a system for calculating a small clear distance tunnel excavation damage area, wherein the method comprises the following steps: it comprises the following steps: s1, setting acoustic wave monitoring points in a tunnel excavation area to acquire corresponding acoustic wave monitoring data; s2, calculating a rock mass blasting damage value corresponding to the acoustic wave monitoring data; s3, creating a relation model of blasting damage and blasting times based on the rock mass blasting damage value; s4, creating an elastoplastic damage model based on Hoek-Brown criteria; and S5, calculating rock mass coupling damage values and displacement values under different blasting times based on the elastoplastic damage model, and obtaining an evaluation result of engineering stability of a tunnel excavation area. The invention better expresses the evolution rule of rock mass damage under the action of cyclic blasting; the distribution characteristics of surrounding rock damaged areas under different blasting times are reflected through the created elastoplastic damage model, so that a better guiding effect is provided for engineering safety design.
Description
Technical Field
The invention relates to the technical field of tunnel stability analysis, in particular to a method and a system for calculating a small clear distance tunnel excavation damaged area.
Background
Tunnel excavation can cause redistribution of ground stress, causing damage to surrounding rock mass, resulting in reduced stability of the tunnel structure. Especially for underground engineering excavated by using a blasting method, the blasting load not only can cause the breakage and stripping of the rock mass in the near zone, but also can cause disturbance to the rock mass in the middle and far zones. In the middle and far areas of blasting, the single blasting stress wave strength is insufficient to directly damage the complete rock mass, but for the structural surface with weak strength, loosening and sliding can occur under the action of weak stress wave, so that the original crack is expanded and extended. Under the action of frequent blasting for many times, the number and the length of cracks are continuously increased to form large main cracks and crack groups, form irreversible damage, weaken physical and mechanical parameters of the rock mass and reduce stability of geotechnical engineering.
Therefore, in the process of tunnel construction design, the damage degree and damage range of the rock mass should be analyzed, but the existing analysis technology only considers the effect of stress redistribution, and does not consider the damage degree and damage range of the rock mass under the effect of cyclic blasting.
Disclosure of Invention
Based on the method, in order to solve the defects existing in the prior art, a calculation method of a small clear distance tunnel excavation damaged area is specially provided.
The method for calculating the small clear distance tunnel excavation damaged area is characterized by comprising the following steps of:
s1, setting acoustic wave monitoring points in a tunnel excavation area to acquire corresponding acoustic wave monitoring data;
s2, calculating a rock mass blasting damage value corresponding to the acoustic wave monitoring data;
s3, creating a relation model of blasting damage and blasting times based on the rock mass blasting damage value;
s4, creating an elastoplastic damage model based on Hoek-Brown criteria;
and S5, calculating rock mass coupling damage values and displacement values under different blasting times based on the elastoplastic damage model, and obtaining an evaluation result of engineering stability of a tunnel excavation area.
Optionally, in one embodiment, a calculation formula corresponding to the rock mass blasting damage value is as follows:
in the formula (1): v 0 The sonic wave velocity of the rock mass before blasting; v is the sonic velocity of the rock mass after blasting.
Optionally, in one embodiment, the relation model of the blasting damage and the blasting times is:
in the formula (2): d (D) b Is the blasting damage value; n is the blasting times; n (N) t For the number of tests, D t Is the corresponding damage value; u, W are all fitting coefficients.
Optionally, in one embodiment, the creating process corresponding to the elastoplastic damage model is:
the elastic-plastic damage model yield criterion expression based on the Hoek-Brown criterion is as follows:
in the formula (3): p is hydrostatic pressure; j (J) 2 Is the second bias force invariant; θ is the rad angle; sigma (sigma) ci Is the uniaxial compressive strength of the complete rock; m is m b And a are both empirical parameters; s is used for reflecting the rock mass breaking degree, then m b The expressions corresponding to s and a are as follows:
in the formulae (4) to (6): GSI is a geological strength index, and is obtained by looking up a table according to the actual condition of the site; m is m i The first experimental parameter is obtained by looking up a table according to the actual condition of the site; d is a disturbance coefficient; using coupled impairment variable D simultaneously c Substituting D in formulas (4) - (5), wherein, due to
D c ＝D b +D m -D b D m (7)
Then elastoplastic damage model D m The expression of (2) is:
in formula (8): the initial slope alpha of the rock material softening curve after damage is in the range of [0, ++ infinity]The method comprises the steps of carrying out a first treatment on the surface of the RockMaximum damage value beta is in the range of [0,1 ]]，Is equivalent plastic strain, and the expression is:
in the formula (9): epsilon p1 、ε p2 、ε p3 The main plastic strain in the directions of the x axis, the y axis and the z axis is respectively;
at the same time, substituting (8) into (7) to update stress value according to the calculated coupling damage value, thereby obtaining the received power
The relation between the true stress and the effective stress of the damaged material is as follows:
where σ is the effective stress tensor.
In addition, a computing system of a small clear distance tunnel excavation damage area is also provided, which comprises:
the data acquisition unit acquires corresponding sound wave monitoring data through sound wave monitoring points arranged in the tunnel excavation area;
the first data acquisition unit is used for calculating a rock burst damage value corresponding to the acoustic wave monitoring data;
a relation model creation unit for creating a relation model of blasting damage and blasting times based on the rock mass blasting damage value;
an elastoplastic damage calculation unit for creating an elastoplastic damage model based on the Hoek-Brown criterion;
and the stability evaluation unit is used for calculating the rock mass coupling damage value and displacement value under different blasting times based on the elastoplastic damage model and acquiring an evaluation result of engineering stability of the tunnel excavation area.
Optionally, in one embodiment, a calculation formula corresponding to the rock mass blasting damage value is as follows:
in the formula (1): v 0 The sonic wave velocity of the rock mass before blasting; v is the sonic velocity of the rock mass after blasting.
Optionally, in one embodiment, the relation model of the blasting damage and the blasting times is:
in the formula (2): d (D) b Is the blasting damage value; n is the blasting times; n (N) t For the number of tests, D t Is the corresponding damage value; u, W is the fitting coefficient.
Optionally, in one embodiment, the creating process corresponding to the elastoplastic damage model is:
the elastic-plastic damage model yield criterion expression based on the Hoek-Brown criterion is as follows:
in the formula (3): p is hydrostatic pressure; j (J) 2 Is the second bias force invariant; θ is the rad angle; sigma (sigma) ci Is the uniaxial compressive strength of the complete rock; m is m b And a are all empirical parameters of dimension one for different rock masses; s is used to reflect the degree of rock mass fragmentation,
then m is b The expressions corresponding to s and a are as follows:
in the formulae (4) to (6): GSI is a geological strength index, and is obtained by looking up a table according to the actual condition of the site; m is m i The first experimental parameter is obtained by looking up a table according to the actual condition of the site; d is a disturbance coefficient; using coupled impairment variable D simultaneously c Substituting D in formulas (4) - (5), wherein, due to
D c ＝D b +D m -D b D m (7)
Then elastoplastic damage model D m The expression of (2) is:
in formula (8): the initial slope alpha of the rock material softening curve after damage is in the range of [0, ++ infinity]The method comprises the steps of carrying out a first treatment on the surface of the The range of the maximum damage value beta of the rock is [0,1 ]]，Is equivalent plastic strain, and the expression is:
in the formula (9): epsilon p1 、ε p2 、ε p3 Is the principal plastic strain in three directions of x axis, y axis and z axis.
At the same time, substituting (8) into (7) to update stress value according to the calculated coupling damage value, thereby obtaining damage
The relation between the real stress and the effective stress of the material is as follows:
where σ is the effective stress tensor.
The implementation of the embodiment of the invention has the following beneficial effects:
according to the invention, through coupling the cyclic blasting accumulated damage and the plastic damage caused by stress redistribution, an elastoplastic damage model based on a generalized H-B criterion and other technologies are established; the evolution rule of rock mass damage under the cyclic blasting effect is well expressed; the distribution characteristics of surrounding rock damaged areas under different blasting times are reflected through the created elastoplastic damage model, so that a better guiding effect is provided for engineering safety design.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Wherein:
FIG. 1 is a flow chart illustrating the core steps of a method for calculating a small clear-distance tunnel excavation damaged area according to one embodiment;
FIG. 2 is a flowchart showing the specific steps of a method for calculating an excavated damaged area of a small clear distance tunnel according to embodiment 1;
FIG. 3 is a diagram of the placement of acoustic monitoring points within the small clear-distance tunnel, according to one embodiment;
FIG. 4 (a) is a graph showing the development of the blast damage corresponding to test hole 1 in FIG. 3;
FIG. 4 (b) is a graph showing the development of the blast damage corresponding to test hole 2 in FIG. 3;
FIG. 4 (c) is a graph showing the development of the blast damage corresponding to test hole 3 in FIG. 3;
FIG. 4 (d) is a graph showing the development of the blast damage corresponding to the test hole 4 in FIG. 3;
FIG. 4 (e) is a graph showing the development of the blast damage corresponding to test hole 5 in FIG. 3;
FIG. 5 is a diagram showing a numerical calculation model corresponding to a certain section in embodiment 1;
FIG. 6 (a) is a graph showing the effect of the coupling damage value corresponding to the number of blasting operations of 1 in FIG. 5;
FIG. 6 (b) is a graph showing the effect of the coupling damage values corresponding to the blasting times of 2 times in FIG. 5;
FIG. 6 (c) is a graph showing the effect of the coupling damage value corresponding to the blasting count of 3 in FIG. 5;
FIG. 6 (d) is a graph showing the effect of the coupling damage values corresponding to the blasting times of 4 times in FIG. 5;
FIG. 6 (e) is a graph showing the effect of the coupling damage values corresponding to the blasting times of 5 times in FIG. 5;
FIG. 6 (f) is a graph showing the effect of the coupling damage values corresponding to the blasting times of 6 times in FIG. 5;
FIG. 6 (g) is a graph showing the effect of the coupling damage value corresponding to the number of blasting operations of FIG. 5 being 7;
FIG. 6 (h) is a graph showing the effect of the coupling damage value corresponding to the blasting times of 8 times in FIG. 5;
FIG. 7 (a) is a graph showing the effect of displacement calculation values at different blasting times in example 1;
FIG. 7 (b) is a graph showing the effect of displacement values under different calculation models in example 1.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. It will be understood that the terms first, second, etc. as used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present application. Both the first element and the second element are elements, but they are not the same element.
In the present embodiment, a method for calculating a small clear distance tunnel excavation damage region is specifically provided, as shown in fig. 1, where the method includes the steps of:
s1, setting acoustic wave monitoring points in a tunnel excavation area to acquire corresponding acoustic wave monitoring data; the sound wave monitoring points can be arranged in front of the back tunnel of the tunnel excavation area for drilling holes at the rock clamping column, and the specific positions are based on actual monitoring requirements;
s2, calculating a rock mass blasting damage value corresponding to the acoustic wave monitoring data;
s3, creating a relation model of blasting damage and blasting times based on the rock mass blasting damage value;
s4, creating an elastoplastic damage model based on Hoek-Brown criteria;
and S5, calculating rock mass coupling damage values and displacement values under different blasting times based on the elastoplastic damage model, and obtaining an evaluation result of engineering stability of a tunnel excavation area.
In some specific embodiments, the rock mass blasting damage value corresponds to a calculation formula:
in the formula (1): v 0 Monitoring the sonic wave velocity of the rock mass before blasting in the numerical value for the sonic wave; v is the sonic wave velocity of the blasted rock mass in the sonic monitoring value.
In some specific embodiments, the following formula is used to fit the blasting damage value test results, and the relation model of the blasting damage and the blasting times is established as follows:
in the formula (2): d (D) b Is the blasting damage value; n is the blasting times; n (N) t For the number of tests, D t Is the corresponding damage value; u, W are fitting coefficients that can be obtained by regression calculation from the acoustic monitoring values.
In some specific embodiments, the creating process corresponding to the elastoplastic injury model is:
the elastic-plastic damage model yield criterion expression based on the Hoek-Brown criterion is as follows:
in the formula (3): p is hydrostatic pressure; j (J) 2 Is the second bias force invariant; θ is the rad angle; sigma (sigma) ci Is the uniaxial compressive strength of the complete rock; m is m b And a are all empirical parameters of dimension one for different rock masses; s is used for reflecting the value range of the breaking degree of the rock mass to be 0.0-1.0, and s=1.0 for the complete rock mass (namely the rock); in some more specific embodiments, tunnel models are built using Abaqus software, and elastoplastic damage models based on the Hoek-Brown criterion are built using the umata subroutine therein, with a yield criterion expression of (3).
Then m is b The expressions corresponding to s and a are as follows:
in the formulae (4) to (6): GSI is a geological strength index, and is obtained by looking up a table according to the actual condition of the site; m is m i The experimental parameters of the first dimension of the rock can also be obtained by looking up a table according to the actual condition of the site; d is a disturbance coefficient, and the value range is 0-1. Meanwhile, one innovation point is to use a coupling damage variable D c Replacing D in formulas (4) - (5) to establish a numerical calculation model under the action of explosion-elastoplastic coupling damage; i.e. due to
D c ＝D b +D m -D b D m (7)
Then elastoplastic damage model D m The expression of (2) is:
in formula (8): the initial slope alpha of the rock material softening curve after damage is in the range of [0, ++ infinity]The method comprises the steps of carrying out a first treatment on the surface of the The range of the maximum damage value beta of the rock is [0,1 ]]，Is equivalent plastic strain, and the expression is:
in the formula (9): epsilon p1 、ε p2 、ε p3 Is the principal plastic strain in three directions of xyz coordinate axis.
And updating the stress value according to the calculated coupling damage value (substituting the formula 8 into 7), wherein the relation between the actual stress and the effective stress of the damaged material is as follows:
meanwhile, as the rigidity of the rock mass material is also affected, the corresponding expression is as follows:
E b ＝(1-D c )E 0
wherein: e (E) 0 For initial rigidity of rock mass material, E b To take into account the rigidity of the rock mass material after damage. And obtaining displacement values under different blasting damage values by using the damage stiffness matrix.
In some specific embodiments, in the step S5, the rock mass coupling damage value and the displacement value under different blasting times can be calculated for the elastoplastic damage model by using a traditional finite element method so as to evaluate the engineering stability, and further an evaluation result of the engineering stability of the tunnel excavation area is obtained.
Based on the same inventive concept, the invention also provides a calculation system of the small clear distance tunnel excavation damaged area, which comprises:
the data acquisition unit acquires corresponding sound wave monitoring data through sound wave monitoring points arranged in the tunnel excavation area, the sound wave monitoring points can be arranged in front of the back tunnel of the tunnel excavation area and used for drilling holes at the rock clamping column, and the specific positions are based on actual monitoring requirements;
the first data acquisition unit is used for calculating a rock burst damage value corresponding to the acoustic wave monitoring data;
a relation model creation unit for creating a relation model of blasting damage and blasting times based on the rock mass blasting damage value;
an elastoplastic damage calculation unit for creating an elastoplastic damage model based on the Hoek-Brown criterion;
and the stability evaluation unit is used for calculating the rock mass coupling damage value and displacement value under different blasting times based on the elastoplastic damage model and acquiring an evaluation result of engineering stability of the tunnel excavation area.
In some specific embodiments, the rock mass blasting damage value corresponds to a calculation formula:
in the formula (1): v 0 The sonic wave velocity of the rock mass before blasting; v is the sonic velocity of the rock mass after blasting.
In some specific embodiments, the blasting damage versus number of blasts is modeled as:
in the formula (2): d (D) b Is the blasting damage value; n is the blasting times; n (N) t For the number of tests, D t Is the corresponding damage value; u, W is the fitting coefficient.
In some specific embodiments, the creating process corresponding to the elastoplastic injury model is:
the elastic-plastic damage model yield criterion expression based on the Hoek-Brown criterion is as follows:
in the formula (3): p is hydrostatic pressure; j (J) 2 Is the second bias force invariant; θ is the rad angle; sigma (sigma) ci Is the uniaxial compressive strength of the complete rock; m is m b And a are all empirical parameters of dimension one for different rock masses; s is used for reflecting the value range of the breaking degree of the rock mass to be 0.0-1.0, and s=1.0 for the complete rock mass (namely the rock); in some more specific embodiments, tunnel models are built using Abaqus software, and elastoplastic damage models based on the Hoek-Brown criterion are built using the umata subroutine therein, with a yield criterion expression of (3).
Then m is b The expressions corresponding to s and a are as follows:
in the formulae (4) to (6): GSI is a geological strength index, and is obtained by looking up a table according to the actual condition of the site; m is m i The first experimental parameter is obtained by looking up a table according to the actual condition of the site; d is a disturbance coefficient; using coupled impairment variable D simultaneously c Substituting D in formulas (4) - (5), wherein, due to
D c ＝D b +D m -D b D m (7)
Then elastoplastic damage model D m The expression of (2) is:
in formula (8): the initial slope alpha of the rock material softening curve after damage is in the range of [0, ++ infinity]The method comprises the steps of carrying out a first treatment on the surface of the The range of the maximum damage value beta of the rock is [0,1 ]]，Is equivalent plastic strain, and the expression is:
in the formula (9): epsilon p1 、ε p2 、ε p3 Is the principal plastic strain in three directions of the xyz axis.
And updating the stress value according to the calculated coupling damage value (substituting the formula 8 into 7), wherein the relation between the actual stress and the effective stress of the damaged material is as follows:
meanwhile, as the rigidity of the rock mass material is also affected, the corresponding expression is as follows:
E b ＝(1-D c )E 0
wherein: e (E) 0 For initial rigidity of rock mass material, E b To take into account the rigidity of the rock mass material after damage. And obtaining displacement values under different blasting damage values by using the damage stiffness matrix.
In some specific embodiments, the rock mass coupling damage value and displacement value under different blasting times can be calculated by using a traditional finite element method on the elastoplastic damage model so as to evaluate engineering stability, and further, an evaluation result of engineering stability of a tunnel excavation area is obtained.
The following will further describe the present invention in specific cases:
this example 1: performing on-site acoustic wave monitoring and numerical stability calculation on the large-connection subway No. 5 line small-clearance tunnel by using the elastoplastic damage model (the specific calculation process is shown in fig. 2); the layout diagram of the monitoring points is shown in fig. 3, wherein A represents a preceding hole, B represents a succeeding hole, C represents a test hole, D represents a blasting area, and E represents an excavation direction; first, equation (2) is fitted according to the acoustic monitoring values, and the results are shown in fig. 4 (a) -4 (e): from the fitting result, the formula (2) can reflect the damage evolution rule of the rock mass under the cyclic blasting effect, and has better feasibility; secondly, carrying out numerical calculation on a certain section on the basis of the monitoring data, and establishing a numerical calculation model as shown in fig. 5; the coupling damage values of different blasting times are calculated as shown in figure 6; as can be seen from fig. 6 (a) -6 (h), under the action of multiple blasting impact, the initial damage value of the rock mass is gradually increased, and due to the existence of load damage, the coupling damage value of the rock mass is also increased compared with that of the initial blasting damage, and the displacement values of key points under different blasting times are extracted and compared with the values without considering the load damage, and the result is shown in fig. 7.
As can be seen from fig. 7 (a), under the action of cyclic blasting load, due to the existence of damage, the mechanical parameters of the rock mass are weakened, so that the hole circumference displacement value is gradually increased; as can be seen from fig. 7 (B), the displacement values calculated from the H-B coupled damage model are larger than those obtained when only a single damage factor is considered, and are closer to the measured values (the results are slightly larger than the measured values due to the consideration of the problem from the most unfavorable point of view). Therefore, the calculation result can be said to show that rock mass damage caused by blasting and stress redistribution is not negligible, and the coupling damage model built in the method has certain superiority compared with the traditional model.
The implementation of the embodiment of the invention has the following beneficial effects:
aiming at the defects of a calculation method for excavating a surrounding rock damaged area of a tunnel by a drilling and blasting method, a Hoek-Brown (hereinafter referred to as H-B) elastoplastic damage model considering a cyclic blasting effect is established, and a numerical solution is provided. The method specifically comprises the following steps: firstly, deriving a middle-far field cyclic blasting accumulated damage evolution formula (2) according to a fatigue damage theory, coupling the cyclic blasting accumulated damage with plastic damage caused by stress redistribution, and establishing an elastoplastic damage model (10) based on a generalized H-B criterion; secondly, a specific numerical solution of the damage model is given by using a completely implicit stress remapping algorithm and an operator separation method, a tunnel model is built based on an ABAQUS platform, an elastoplastic damage model based on a Hoek-Brown criterion is built by using a Umat subroutine in the tunnel model, and the elastoplastic damage model is solved based on a finite element solver; and finally, in the surrounding rock stability analysis of the large continuous subway engineering, verifying a medium-far field circulation blasting damage evolution formula through on-site acoustic wave monitoring, and calculating the displacement value and damage area distribution characteristics of the researched section. The results show that: the evolution formula of the accumulated damage of the cyclic blasting can better express the evolution rule of the damage of the rock mass under the action of the cyclic blasting; the built elastoplastic damage model can reflect the distribution characteristics of surrounding rock damage areas under different blasting times, has more advantages than the traditional method, and has better guiding effect on engineering safety design.
The above examples only represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the present application. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.
Claims (2)
1. The method for calculating the small clear distance tunnel excavation damaged area is characterized by comprising the following steps of:
s1, setting acoustic wave monitoring points in a tunnel excavation area to acquire corresponding acoustic wave monitoring data;
s2, calculating a rock mass blasting damage value corresponding to the acoustic wave monitoring data;
s3, creating a relation model of blasting damage and blasting times based on the rock mass blasting damage value;
s4, creating an elastoplastic damage model based on Hoek-Brown criteria;
s5, calculating rock mass coupling damage values and displacement values under different blasting times based on the elastoplastic damage model, and acquiring an evaluation result of engineering stability of a tunnel excavation area; the calculation formula corresponding to the rock mass blasting damage value comprises the following steps:
in the formula (1): v 0 The sonic wave velocity of the rock mass before blasting; v is the sonic wave velocity of the rock mass after blasting; the relation model of the blasting damage and the blasting times is as follows:
in the formula (2): d (D) b Is the blasting damage value; n is the blasting times; n (N) t For the number of tests, D t Is the corresponding damage value; u, W are fitting coefficients; the creation process corresponding to the elastoplastic damage model is as follows:
the elastic-plastic damage model yield criterion expression based on the Hoek-Brown criterion is as follows:
in the formula (3): p is hydrostatic pressure; j (J) 2 Is the second bias force invariant; θ is the rad angle; sigma (sigma) ci Is the uniaxial compressive strength of the complete rock; m is m b And a are both empirical parameters; s is used for reflecting the rock mass breaking degree, then m b The expressions corresponding to s and a are as follows:
in the formulae (4) to (6): GSI is a geological strength index, and is obtained by looking up a table according to the actual condition of the site; m is m i The first experimental parameter is obtained by looking up a table according to the actual condition of the site; d is a disturbance coefficient; using coupled impairment variable D simultaneously c Substituting D in formulas (4) - (5), wherein, due to
D c ＝D b +D m -D b D m (7)
Then elastoplastic damage model D m The expression of (2) is:
in formula (8): the initial slope alpha of the rock material softening curve after damage is in the range of [0, ++ infinity]The method comprises the steps of carrying out a first treatment on the surface of the The range of the maximum damage value beta of the rock is [0,1 ]]，Is equivalent plastic strain, and the expression is:
in the formula (9): epsilon p1 、ε p2 、ε p3 The main plastic strain in the directions of the x axis, the y axis and the z axis is respectively;
meanwhile, substituting (8) into (7) to update the stress value according to the calculated coupling damage value, so as to obtain a relation between the actual stress and the effective stress of the damaged material, wherein the relation is as follows:
where σ is the effective stress tensor.
2. A computing system for excavating a damaged area of a small clear-distance tunnel, comprising:
the data acquisition unit acquires corresponding sound wave monitoring data through sound wave monitoring points arranged in the tunnel excavation area;
the first data acquisition unit is used for calculating a rock burst damage value corresponding to the acoustic wave monitoring data;
a relation model creation unit for creating a relation model of blasting damage and blasting times based on the rock mass blasting damage value;
an elastoplastic damage calculation unit for creating an elastoplastic damage model based on the Hoek-Brown criterion;
the stability evaluation unit is used for calculating rock mass coupling damage values and displacement values under different blasting times based on the elastoplastic damage model and obtaining an evaluation result of engineering stability of a tunnel excavation area; the calculation formula corresponding to the rock mass blasting damage value comprises the following steps:
in the formula (1)：v 0 The sonic wave velocity of the rock mass before blasting; v is the sonic wave velocity of the rock mass after blasting;
the relation model of the blasting damage and the blasting times is as follows:
in the formula (2): d (D) b Is the blasting damage value; n is the blasting times; n (N) t For the number of tests, D t Is the corresponding damage value; u, W is the fitting coefficient, and the corresponding creation process of the elastoplastic injury model is as follows:
the elastic-plastic damage model yield criterion expression based on the Hoek-Brown criterion is as follows:
in the formula (3): p is hydrostatic pressure; j (J) 2 Is the second bias force invariant; θ is the rad angle; sigma (sigma) ci Is the uniaxial compressive strength of the complete rock; m is m b And a are all empirical parameters of dimension one for different rock masses; s is used to reflect the degree of rock mass fragmentation,
then m is b The expressions corresponding to s and a are as follows:
in the formulae (4) to (6): GSI is a geological strength index, and is obtained by looking up a table according to the actual condition of the site; m is m i Is an empirical parameter of the first dimension of the rock according to the actual condition of the siteKuang Chabiao; d is a disturbance coefficient; using coupled impairment variable D simultaneously c Substituting D in formulas (4) - (5), wherein, due to
D c ＝D b +D m -D b D m (7)
Then elastoplastic damage model D m The expression of (2) is:
in formula (8): the initial slope alpha of the rock material softening curve after damage is in the range of [0, ++ infinity]The method comprises the steps of carrying out a first treatment on the surface of the The range of the maximum damage value beta of the rock is [0,1 ]]，Is equivalent plastic strain, and the expression is:
in the formula (9): epsilon p1 、ε p2 、ε p3 The main plastic strain in the three directions of the x axis, the y axis and the z axis is obtained;
meanwhile, substituting (8) into (7) to update the stress value according to the calculated coupling damage value, so as to obtain a relation between the actual stress and the effective stress of the damaged material, wherein the relation is as follows:
where σ is the effective stress tensor.
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