CN116106125A - Method for evaluating brittleness degree of rock - Google Patents
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Abstract
The application relates to a method for evaluating rock brittleness degree, and relates to the technical field of underground engineering safety. The method comprises the following steps: acquiring the peak strength, peak strain, elastic modulus and crack closure strain corresponding to the rock to be tested in a compression test; determining the actual accumulation elastic energy before the peak and the accumulation strain energy in the ideal elastic deformation process before the peak corresponding to the rock to be tested according to the peak strength, the peak strain, the elastic modulus and the crack closure strain; determining the ratio of the actual accumulation elastic energy before the peak to the accumulation strain energy in the ideal elastic deformation process before the peak as the accumulation rate of the elastic energy before the peak corresponding to the rock to be detected; and determining the ratio of the pre-peak elastic energy accumulation rate to the peak strain as a brittleness evaluation index corresponding to the rock to be tested. The method and the device can enable the determination of the rock brittleness evaluation index to be simpler, more reasonable and more reliable.
Description
Technical Field
The application relates to the technical field of underground engineering safety, in particular to a method for evaluating the brittleness degree of rock.
Background
Brittleness refers to the property that rock is suddenly damaged and loses bearing capacity when being deformed very little under the action of external force, and is one of important mechanical properties of rock. The quantitative evaluation of the brittleness degree of the rock can provide an important reference basis for predicting the occurrence of the rock burst of the deep-buried high-ground-stress tunnel and judging the tendency of the rock burst. So far, students at home and abroad establish nearly hundred rock brittleness evaluation indexes by means of different research methods and means aiming at various engineering practices, and main means comprise rock strength parameters, deformation parameters, mineral composition components, stress-strain curve forms, energy evolution processes and the like.
However, in the existing indexes for quantitatively evaluating the brittleness degree of the rock, although part of indexes comprehensively consider deformation mechanical characteristics or energy evolution characteristics before and after a rock peak, the construction process and the calculation method are complex; there is also a problem that the evaluation result of the brittleness degree is inaccurate in some indexes. Therefore, it is highly demanded to establish a method for evaluating the degree of rock brittleness, which can obtain an accurate evaluation result of the degree of brittleness through a simple calculation process.
Disclosure of Invention
In view of the above, it is desirable to provide a method for evaluating the brittleness of rock.
In a first aspect, there is provided a method of evaluating the brittleness of rock, the method comprising:
acquiring the peak strength, peak strain, elastic modulus and crack closure strain corresponding to the rock to be tested in a compression test;
determining the actual accumulation elastic energy before the peak and the accumulation strain energy in the ideal elastic deformation process before the peak corresponding to the rock to be tested according to the peak strength, the peak strain, the elastic modulus and the crack closure strain;
determining the ratio of the actual accumulation elastic energy before the peak to the accumulation strain energy in the ideal elastic deformation process before the peak as the accumulation rate of the elastic energy before the peak corresponding to the rock to be detected;
and determining the ratio of the pre-peak elastic energy accumulation rate to the peak strain as a brittleness evaluation index corresponding to the rock to be tested.
As an optional implementation manner, the determining the actual accumulation elastic energy before peak and the ideal accumulation strain energy during the ideal elastic deformation process before peak corresponding to the rock to be tested according to the peak strength, the peak strain, the elastic modulus and the crack closure strain includes:
determining the actual accumulated elastic energy before the peak according to the peak strength and the elastic modulus;
and determining the ideal elastic deformation process accumulated strain energy before the peak according to the peak strain, the elastic modulus and the crack closure strain.
As an alternative embodiment, the formula for determining the actual accumulated elastic energy before the peak according to the peak strength and the elastic modulus is as follows:
wherein, W 1 indicating the actual accumulation of elastic energy before the peak,σ p the peak intensity is indicated as such,Ethe elastic modulus is shown.
As an alternative embodiment, said determining the ideal elastic deformation process accumulated strain energy before the peak according to the peak strain, the elastic modulus and the crack closure strain comprises:
determining the difference value of the peak strain and the crack closure strain as the deformation corresponding to the ideal elastic deformation process before the peak corresponding to the rock to be detected;
and determining accumulated strain energy in the ideal elastic deformation process before the peak according to the deformation amount corresponding to the ideal elastic deformation process before the peak and the elastic modulus.
As an optional implementation manner, the formula for determining the accumulated strain energy of the ideal elastic deformation process before the peak according to the deformation amount corresponding to the ideal elastic deformation process before the peak and the elastic modulus is:
wherein, W 2 indicating the ideal elastic deformation process before the peak accumulates strain energy,ε' represents the deformation corresponding to the ideal elastic deformation process before the peak,Ethe elastic modulus is shown.
In a second aspect, there is provided an apparatus for evaluating the brittleness of rock, the apparatus comprising:
the acquisition module is used for acquiring peak strength, peak strain, elastic modulus and crack closure strain corresponding to the rock to be tested in the compression test;
the first determining module is used for determining the actual accumulation elastic energy before the peak and the ideal elastic deformation process accumulation strain energy before the peak corresponding to the rock to be tested according to the peak strength, the peak strain, the elastic modulus and the crack closure strain;
the second determining module is used for determining the ratio of the actual accumulated elastic energy before the peak to the accumulated strain energy in the ideal elastic deformation process before the peak as the accumulation rate of the elastic energy before the peak corresponding to the rock to be detected;
and the third determining module is used for determining the ratio of the pre-peak elastic energy accumulation rate to the peak strain as a brittleness evaluation index corresponding to the rock to be tested.
As an optional implementation manner, the first determining module is specifically configured to:
determining the actual accumulated elastic energy before the peak according to the peak strength and the elastic modulus;
and determining the ideal elastic deformation process accumulated strain energy before the peak according to the peak strain, the elastic modulus and the crack closure strain.
As an optional implementation manner, the first determining module is specifically configured to:
determining the difference value of the peak strain and the crack closure strain as the deformation corresponding to the ideal elastic deformation process before the peak corresponding to the rock to be detected;
and determining accumulated strain energy in the ideal elastic deformation process before the peak according to the deformation amount corresponding to the ideal elastic deformation process before the peak and the elastic modulus.
In a third aspect, a computer device is provided, comprising a memory and a processor, the memory having stored thereon a computer program executable on the processor, the processor implementing the method steps according to the first aspect when the computer program is executed.
In a fourth aspect, a computer-readable storage medium is provided, on which a computer program is stored which, when being executed by a processor, carries out the method steps according to the first aspect.
The application provides a method for evaluating the brittleness degree of rock, and the technical scheme provided by the embodiment of the application at least brings the following beneficial effects: firstly, the computer equipment acquires the peak strength, peak strain, elastic modulus and crack closure strain corresponding to the rock to be tested in the compression test. And then, the computer equipment determines the actual accumulation elastic energy before the peak and the ideal elastic deformation process accumulation strain energy before the peak corresponding to the rock to be measured according to the peak strength, the peak strain, the elastic modulus and the crack closure strain, and determines the ratio of the actual accumulation elastic energy before the peak to the ideal elastic deformation process accumulation strain energy before the peak as the accumulation rate of the elastic energy before the peak corresponding to the rock to be measured. And finally, the computer equipment determines the ratio of the pre-peak elastic energy accumulation rate to the peak strain as a brittleness evaluation index corresponding to the rock to be tested. According to the brittleness evaluation index provided by the application, the rock brittleness evaluation index can be determined more simply, reasonably and reliably by comprehensively considering the pre-peak elastic energy accumulation rate and the deformation value at the breaking moment of the rock.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
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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.
FIG. 1 is a schematic representation of a typical stress-strain curve of a rock under uniaxial compression provided in an embodiment of the present application;
FIG. 2 is a flow chart of a method for evaluating rock brittleness according to an embodiment of the present application;
FIG. 3 is a schematic diagram of a calculation model of a brittleness evaluation index according to an embodiment of the present application;
fig. 4 is a schematic diagram of a uniaxial compressive stress-strain curve of a rock to be tested according to an embodiment of the present application;
FIG. 5 is a schematic structural view of an apparatus for evaluating rock brittleness according to an embodiment of the present application;
fig. 6 is a schematic structural diagram of a computer device according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.
In the construction design of underground engineering, in order to ensure construction safety, prediction of the occurrence of rock burst of a deep-buried high-ground-stress tunnel and judgment of the tendency of rock burst are generally required, and the method for evaluating the rock brittleness degree provided by the embodiment of the application can be applied to the quantitative evaluation process of the rock brittleness degree and can provide an accurate reference basis for predicting the occurrence of rock burst of the deep-buried high-ground-stress tunnel and judging the tendency of rock burst.
The energy evolution mechanism in the rock breaking process can be revealed by analyzing the breaking mechanism of the rock through the energy angle, and the essential characteristics of rock breaking can be reflected. Therefore, in order to enable the finally determined brittleness evaluation index to more accurately reflect the brittleness damage degree of the rock to be tested, the embodiment of the application establishes the brittleness evaluation index considering the energy evolution of the rock to be tested in the test process from the energy perspective.
For easy understanding, the energy evolution process of the rock during the test will be briefly described, and FIG. 1 shows a rock under uniaxial compression according to an embodiment of the present applicationWherein the abscissa represents the strain [ ]ε) The ordinate indicates stress [ ]σ) As shown in fig. 1, a typical stress-strain curve of rock under uniaxial compression generally undergoes 4 stages: initial compaction deformation stageOASegment, elastic deformation stage of wireABStage of plastic deformationBCSegment) and post-peak destruction stageCDSegments). Wherein the initial compaction deformation stage, the linear elastic deformation stage and the plastic deformation stage are pre-peak stages. From the angle analysis of energy evolution, the rock is mainly accumulated by elastic strain energy in the pre-peak stage, and a small part of energy is dissipated due to initial micro-crack compaction and closure and micro-crack initiation and expansion in the plastic deformation stage; during the post-peak failure phase, a large amount of strain energy accumulated inside the rock is rapidly released and the dissipated energy increases rapidly.
The method for evaluating the rock brittleness degree provided in the embodiment of the present application will be described in detail with reference to the specific embodiment, and fig. 2 is a flowchart of a method for evaluating the rock brittleness degree provided in the embodiment of the present application, and as shown in fig. 2, the specific steps are as follows:
and step 201, obtaining the peak strength, peak strain, elastic modulus and crack closure strain corresponding to the rock to be tested in the compression test.
In practice, first, rock samples of different lithologies (i.e., rock to be tested) retrieved from an engineering site are processed into samples of a preset size. Preferably, the sample of the preset size is a standard cylindrical sample of 100mm in height and 50mm in diameter. Then, a compression test was performed on the specimen, and the peak strength (which may also be referred to as peak stress), peak strain, elastic modulus, and crack closure strain corresponding to the specimen in the compression test were obtained. The peak strength, peak strain, elastic modulus and crack closure strain can be determined according to stress strain data corresponding to the sample in a compression test; the compression test may be a uniaxial compression test or a triaxial compression test. Preferably, the compression test is a room uniaxial compression test and the stress strain data is a uniaxial compressive stress-strain curve.
Further, the process of determining peak strength, peak strain, elastic modulus and crack closure strain by the computer device according to the stress-strain data corresponding to the sample in the compression test is as follows: determining the ordinate of a peak point of the stress-strain curve on the vertical axis as the peak strength of the rock to be tested, and determining the abscissa as the peak strain of the rock to be tested; determining the slope of the line elastic deformation stage in the stress-strain curve as the elastic modulus of the rock to be tested; and determining the abscissa of the intersection point of the reverse extension line of the line elastic deformation stage in the stress-strain curve and the transverse axis as the crack closure strain of the rock to be tested.
In practice, FIG. 3 is a schematic diagram of a calculation model of a brittleness evaluation index according to the embodiment of the present application, as shown in FIG. 3, the abscissa represents strain [ ]ε) The ordinate indicates stress [ ]σ). Curve of curveOABCDRepresenting a stress-strain curve corresponding to the rock to be tested, wherein,ABthe segment represents the elastic deformation stage of the line, and the elastic property of the rock to be tested can be reflected because the stage has almost no plastic deformationABThe slope of the segment is determined as the modulus of elasticity of the rock to be tested.CThe points are curvesOABCDPeak point on vertical axis, can beCThe ordinate of the point is determined as the peak strength of the rock to be measured, and the abscissa is determined as the peak strain of the rock to be measured.FThe points areABIntersection of reverse extension line of segment and transverse axis can makeFThe abscissa of the point is determined as the crack closure strain of the rock to be tested.
And 202, determining the actual accumulated elastic energy before the peak and the accumulated strain energy in the ideal elastic deformation process before the peak corresponding to the rock to be tested according to the peak strength, the peak strain, the elastic modulus and the crack closure strain.
In the implementation, the actual accumulation elastic energy before the peak corresponding to the rock to be tested represents the energy stored in the rock to be tested as elastic strain energy in the energy input by external load acting in the compression test. The accumulated strain energy in the ideal elastic deformation process before the peak corresponding to the rock to be measured represents the energy which can be stored in the rock to be measured by the elastic strain energy in the energy input by external load acting when the ideal elastic deformation state before the peak exists. The computer equipment can determine the actual accumulation elastic energy before the peak and the ideal elastic deformation process accumulation strain energy before the peak corresponding to the rock to be tested according to the physical significance of the actual accumulation elastic energy before the peak and the accumulated strain energy in the ideal elastic deformation process before the peak according to the peak strength, the peak strain, the elastic modulus and the crack closure strain.
It should be noted that for a homogeneous, complete, high hardness rock, the nonlinear deformation of the initial compaction phase is not apparent, and the line elastic deformation phase is entered immediately after loading, i.e. the energy dissipation for initial microcrack compaction closure is negligible. However, in engineering practice, the interior of the rock subjected to various disturbance actions contains more or less initial damages such as microcracks, microcracks and the like, and thus the crack closure effect of the rock during the compression deformation is caused. When the initial microcracks and microcracks are compressed and closed in the initial compaction stage, the rock is closest to an ideal elastic state which is intact, and then the energy in the rock is continuously accumulated in the online elastic deformation stage, so that the actual pre-peak energy dissipation is caused by the development and expansion of new cracks and plastic deformation of the rock after the load exceeds the cracking stress. Wherein, as shown in figure 3,BCthe segments represent the phase of plastic deformation,Bthe points are the rock elastic deformation end point and the plastic deformation start point, and the cracking stress is equal toBThe ordinate corresponding to the point.
Therefore, in order to make the finally determined brittleness evaluation index more accurately reflect the brittleness damage degree of the rock to be tested, in the embodiment of the application, when the brittleness evaluation index is established from the energy evolution angle, the energy dissipated by the nonlinear deformation and crack closure friction action generated by the rock mass in the initial compaction stage (namely, the energy dissipated by the compaction closure of the microcracks can be equivalent to that shown in fig. 3OAA segment(s),ABThe reverse extension line of the section and the cross shaftOAFThe area of the steel plate) and the rock to be tested are subjected to the main consideration factors of the actual accumulation of elastic energy before the peak and the accumulation of strain energy in the ideal elastic deformation process before the peak, which correspond to the rock to be tested, as the brittleness evaluation index.
As an alternative implementation manner, the computer equipment determines the actual accumulation elastic energy before the peak and the accumulation strain energy in the ideal elastic deformation process before the peak corresponding to the rock to be tested according to the peak strength, the peak strain, the elastic modulus and the crack closure strain, and the processing procedure is as follows:
step one, determining the actual accumulated elastic energy before the peak according to the peak strength and the elastic modulus.
In an implementation, as shown in figure 3,Hthe points areCThe point is the projected point of the horizontal axis,Gthe point is too muchCThe point is the intersection of a straight line with the elastic modulus as a slope and the transverse axis. Because the actual accumulation elastic energy before the peak represents the energy stored in the rock to be tested in the form of elastic strain energy in the energy input by external load acting in the compression test, the actual accumulation elastic energy before the peak can be equivalentlyΔGCHArea (i.e. S) GCHΔ ). In this way, the computer device can determine S based on the peak strength and the elastic modulus GCHΔ And further determining the actual accumulated elastic energy before the peak of the rock to be tested.
Further, according to the peak strength and the elastic modulus of the rock to be tested, the computer equipment determines the formula of the actual accumulated elastic energy before the peak as follows:
wherein, W 1 indicating the actual accumulated elastic energy before peak, S GCHΔ Representation ofΔGCHIs defined by the area of the (c),σ p the peak intensity is indicated as such,Ethe elastic modulus is shown.
And step two, determining the accumulated strain energy in the ideal elastic deformation process before the peak according to the peak strain, the elastic modulus and the crack closure strain.
In an implementation, as shown in figure 3,Ithe points areABThe extension line of the segment crosses the transverse axisCIntersection of perpendicular lines of points. Because the accumulated strain energy in the ideal elastic deformation process before the peak represents the energy which can be stored in the rock to be measured as the elastic strain energy in the energy input by the external load working when the ideal elastic deformation state before the peak is located, the accumulated strain energy in the ideal elastic deformation process before the peak can be equivalentlyΔFIHArea (i.e. S) FIHΔ ). This isThe computer device may determine S based on peak strain, elastic modulus, and crack closure strain FIHΔ And further determining the ideal elastic deformation process accumulated strain energy before the peak of the rock to be measured.
As an alternative embodiment, the computer device determines the ideal elastic deformation process before the peak to accumulate strain energy according to the peak strain, the elastic modulus and the crack closure strain as follows:
and step one, determining the difference value of the peak strain and the crack closure strain as the deformation corresponding to the ideal elastic deformation process before the peak corresponding to the rock to be detected.
In practice, as shown in FIG. 3, the computer device may determine the difference between the peak strain and the crack closure strain as the deformation (corresponding line segment) corresponding to the pre-peak ideal elastic deformation process for the rock under testFH）。
And step two, determining accumulated strain energy in the ideal elastic deformation process before the peak according to the deformation amount and the elastic modulus corresponding to the ideal elastic deformation process before the peak.
In implementation, the computer equipment can determine the accumulated strain energy of the rock to be measured in the pre-peak ideal elastic deformation process according to the deformation and the elastic modulus corresponding to the pre-peak ideal elastic deformation process, and the formula is as follows:
wherein, W 2 represents the ideal elastic deformation process before peak accumulating strain energy S FIHΔ Representation ofΔFIHIs defined by the area of the (c),ε' represents the deformation corresponding to the ideal elastic deformation process before the peak,Ethe elastic modulus is shown.
And 203, determining the ratio of the actual accumulation elastic energy before the peak to the accumulation strain energy in the ideal elastic deformation process before the peak as the accumulation rate of the elastic energy before the peak corresponding to the rock to be measured.
In practice, the ability of rock to resist inelastic deformation in the pre-peak stage is the main mechanical manifestation of brittle strength: the stronger the rock is against inelastic deformation in the pre-peak stage, i.eThe stronger the elastic deformation capability of the rock in the pre-peak stage, the more energy stored in the rock by elastic strain energy in the energy input by external load work, the lower the plastic deformation capability and crack expansion degree in the pre-peak stage, the less the dissipated energy (i.e. S GCHΔ /S FIHΔ The larger); thus, the more elastic strain energy is released by the rock during the post-peak failure phase, and thus the higher the degree of brittle failure. Conversely, the weaker the rock is in its ability to resist inelastic deformation during the pre-peak phase, the greater the plastic deformation of the rock during the pre-peak phase, the more the internal cracks of the rock can develop and propagate sufficiently, and correspondingly the more energy is dissipated (i.e., S GCHΔ /S FIHΔ The smaller); thus, the less elastic strain energy is released by the rock during the post-peak failure phase, the weaker the degree of brittle failure is exhibited. Thus, the examples herein compare the ratio of the actual accumulated elastic energy before peak to the accumulated strain energy during ideal elastic deformation before peak (i.e., S GCHΔ /S FIHΔ ) The pre-peak elastic energy accumulation rate corresponding to the rock to be measured is determined and used for representing the pre-peak brittleness degree of the rock to be measured (namely, the pre-peak brittleness index of the rock to be measured can be used as), and the capacity of the rock to be measured for resisting inelastic deformation in the pre-peak stage is reflected. Wherein the magnitude of the pre-peak elastic energy accumulation rate is positively correlated with the brittleness of the rock.
As an alternative embodiment, the pre-peak elastic energy accumulation rate can be determined by the following formula:
wherein, B pre represents the pre-peak elastic energy accumulation rate, S GCHΔ Indicating the actual accumulated elastic energy before peak, S FIHΔ Indicating the ideal elastic deformation process before the peak accumulates strain energy,σ p the peak intensity is indicated as such,Ethe modulus of elasticity is indicated as being,ε p indicating the peak strain of the material,ε cc indicating crack closure strain.
When the rock is in front of the peakWhen the stage is in ideal elastic deformation state, the mechanical energy input by external load acting is completely converted into elastic strain energy and stored in the rock, at the moment S GCHΔ =S FIHΔ ，B pre =1; when the rock is in a complete plastic deformation state in the pre-peak stage, the mechanical energy input by external load acting is completely used for converting crack propagation behavior into dissipation energy, and S GCHΔ =0，B pre =0. In the actual engineering practice of the present invention,B pre the value range of (1) is (0).
And 204, determining the ratio of the pre-peak elastic energy accumulation rate to the peak strain as a brittleness evaluation index corresponding to the rock to be tested.
In practice, it is known from the definition of rock brittleness that the smaller the peak strain of the rock, the smaller the axial deformation of the rock at the moment of failure, the higher the degree of brittleness. That is, the brittleness of the rock is inversely proportional to the peak strain. Therefore, in order to comprehensively consider the elastic energy accumulation rate and the peak damage deformation of the rock to be tested in the pre-peak stage, the ratio of the elastic energy accumulation rate to the peak strain before the peak is determined as the brittleness evaluation index corresponding to the rock to be tested, so that the method has certain rationality and reliability, can accurately reflect the brittleness damage degree of the rock to be tested, has the advantages of simple form and less parameters, and is suitable for judging the brittleness degree of the rock under the conventional conditions.
As an alternative embodiment, the brittleness evaluation index corresponding to the rock to be tested can be determined by the following formula:
wherein, Bthe index of the brittle quality evaluation is shown,σ p the peak intensity is indicated as such,Ethe modulus of elasticity is indicated as being,ε p indicating the peak strain of the material,ε cc indicating crack closure strain.BThe larger the calculation result of (2) is, the higher the brittleness degree of the rock to be measured is.
For ease of understanding, embodiments of the present application provide an example of an application of a method for evaluating the brittleness of rock:
step one, processing three rock samples with different lithologies, namely quartz schist, two-long granite and lamellar siltstone, which are taken from an engineering site, into standard cylinder samples with the height of 100mm and the diameter of 50mm, and then carrying out an indoor uniaxial compression test to obtain uniaxial compression stress-strain curves of the three samples (namely the rock to be tested). For example, fig. 4 is a schematic diagram of a uniaxial compressive stress-strain curve of a rock to be tested according to an embodiment of the present application, as shown in fig. 4, the abscissa represents axial strain [ ]%) The ordinate indicates the axial stress [ (]MPa) The uniaxial compressive stress-strain curves (i.e. test curves) of the rock to be tested of different lithology show a certain difference.
Step two, as shown in table 1, according to the uniaxial compressive stress-strain curve corresponding to each rock to be tested, determining the peak strength, peak strain, elastic modulus and crack closure strain (i.e. the brittleness evaluation index parameter value) corresponding to each rock to be tested, and then determining the brittleness evaluation index corresponding to each rock to be tested according to the brittleness evaluation index parameter value corresponding to each rock to be tested. The magnitude relation of the brittleness degree of the three kinds of rock to be tested is known by combining the characteristics of the test curve and the brittleness evaluation index obtained by qualitatively analyzing the curve shape of the test curve in fig. 4: quartz schist > two-long granite > lamellar siltstone, consistent with actual friability performance in the test: the quartz schist and the two-long granite are not subjected to plastic deformation in the pre-peak stage, which shows that the pre-peak elastic energy accumulation rate is close to 1 and is close to an ideal brittle state, but the strain value of the quartz schist at the breaking moment is smaller, and the brittle fracture breaking and plastic deformation exist in the post-peak breaking stage, so that the brittleness degree of the quartz schist is greater than that of the two-long granite; the layered siltstone has the greatest amount of pre-peak deformation (most pronounced plastic deformation before peak), and the lowest peak strength and modulus of elasticity, and therefore the weakest degree of brittleness.
TABLE 1 brittleness evaluation index parameter values of rock to be tested
Further, in order to verify the rationality and reliability of the brittleness evaluation index set forth in the examples of the present application, the calculation methods of 4 representative rock brittleness evaluation indexes are listed in table 2, and the method for evaluating the degree of rock brittleness set forth in the examples of the present application will be discussed and analyzed in comparison with the existing representative brittleness evaluation methods listed in table 2.
TABLE 2 evaluation index of representative rock friability
The brittleness evaluation results calculated under uniaxial compression conditions using the brittleness evaluation indexes set forth in the examples of the present application and the 4 representative rock brittleness evaluation indexes set forth in table 2, respectively, are set forth in table 3.
TABLE 3 evaluation results of brittleness of rock of different lithology under uniaxial compression condition
As can be seen from Table 3, the brittleness evaluation index according to the embodiment of the present applicationBEvaluation results and brittleness evaluation indexes of three rocks to be testedB i The evaluation results are consistent, and the evaluation results conform to the actual brittle behavior of three rocks to be tested in the test. Brittle evaluation indexB d 、B s AndBEthe evaluation results of (2) are greatly different from the actual brittle performance of three rocks to be tested in the test. Wherein, B d andB s only the stress drop degree and the stress drop rate of the rear section of the peak of the stress-strain curve of the rock are considered, but the mechanical characteristics before the peak and the deformation value at the breaking moment of the rock are not considered, so that the rationality exists, and the brittleness of the rock cannot be accurately evaluated.
The embodiment of the application provides a method for evaluating the brittleness degree of rock, firstly, computer equipment acquires peak strength, peak strain, elastic modulus and crack closure strain corresponding to rock to be tested in a compression test. And then, the computer equipment determines the actual accumulation elastic energy before the peak and the ideal elastic deformation process accumulation strain energy before the peak corresponding to the rock to be measured according to the peak strength, the peak strain, the elastic modulus and the crack closure strain, and determines the ratio of the actual accumulation elastic energy before the peak to the ideal elastic deformation process accumulation strain energy before the peak as the accumulation rate of the elastic energy before the peak corresponding to the rock to be measured. And finally, the computer equipment determines the ratio of the pre-peak elastic energy accumulation rate to the peak strain as a brittleness evaluation index corresponding to the rock to be tested. According to the brittleness evaluation index provided by the application, the rock brittleness evaluation index can be determined more simply, reasonably and reliably by comprehensively considering the pre-peak elastic energy accumulation rate and the deformation value at the breaking moment of the rock.
It should be understood that, although the steps in the flowchart of fig. 2 are shown in sequence as indicated by the arrows, the steps are not necessarily performed in sequence as indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least a portion of the steps in fig. 2 may include a plurality of steps or stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of the steps or stages is not necessarily sequential, but may be performed in rotation or alternatively with at least a portion of the steps or stages in other steps or other steps.
It should be understood that the same/similar parts of the embodiments of the method described above in this specification may be referred to each other, and each embodiment focuses on differences from other embodiments, and references to descriptions of other method embodiments are only needed.
The embodiment of the application also provides a device for evaluating the brittleness degree of the rock, as shown in fig. 5, the device comprises:
the obtaining module 510 is configured to obtain peak strength, peak strain, elastic modulus and crack closure strain corresponding to the rock to be tested in the compression test;
the first determining module 520 is configured to determine, according to the peak strength, the peak strain, the elastic modulus, and the crack closure strain, the pre-peak actually accumulated elastic energy and the pre-peak ideal elastic deformation accumulated strain energy corresponding to the rock to be tested;
a second determining module 530, configured to determine a ratio of the actual pre-peak accumulated elastic energy to the accumulated strain energy in the pre-peak ideal elastic deformation process as a pre-peak elastic energy accumulation rate corresponding to the rock to be measured;
and a third determining module 540, configured to determine a ratio of the pre-peak elastic energy accumulation rate to the peak strain as a brittleness evaluation index corresponding to the rock to be tested.
As an alternative embodiment, the first determining module is specifically configured to:
determining the actual accumulated elastic energy before the peak according to the peak strength and the elastic modulus;
and determining the ideal elastic deformation process accumulated strain energy before the peak according to the peak strain, the elastic modulus and the crack closure strain.
As an alternative embodiment, the first determining module is specifically configured to:
determining the difference value of the peak strain and the crack closure strain as the deformation corresponding to the ideal elastic deformation process before the peak corresponding to the rock to be detected;
and determining the accumulated strain energy in the ideal elastic deformation process before the peak according to the deformation amount and the elastic modulus corresponding to the ideal elastic deformation process before the peak.
The embodiment of the application provides a device for evaluating the brittleness degree of rock, which comprises the following steps of firstly, acquiring the corresponding peak strength, peak strain, elastic modulus and crack closure strain of rock to be tested in a compression test. And then, according to the peak strength, the peak strain, the elastic modulus and the crack closure strain, determining the actual accumulation elastic energy before the peak and the ideal elastic deformation process accumulation strain energy before the peak corresponding to the rock to be detected, and determining the ratio of the actual accumulation elastic energy before the peak to the ideal elastic deformation process accumulation strain energy before the peak as the accumulation rate of the elastic energy before the peak corresponding to the rock to be detected. And finally, determining the ratio of the pre-peak elastic energy accumulation rate to the peak strain as a brittleness evaluation index corresponding to the rock to be tested. According to the brittleness evaluation index provided by the application, the rock brittleness evaluation index can be determined more simply, reasonably and reliably by comprehensively considering the pre-peak elastic energy accumulation rate and the deformation value at the breaking moment of the rock.
The specific definition of the means for evaluating the degree of rock brittleness can be found in the above definition of the method for evaluating the degree of rock brittleness, and will not be described in detail herein. The individual modules in the above-described apparatus for assessing rock fragility may be implemented in whole or in part by software, hardware, and combinations thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.
In one embodiment, a computer device is provided, as shown in fig. 6, comprising a memory and a processor, the memory having stored thereon a computer program executable on the processor, the processor performing the method steps of assessing rock friability as described above when executing the computer program.
In one embodiment, a computer readable storage medium has stored thereon a computer program which, when executed by a processor, implements the steps of the method of assessing rock friability described above.
Those skilled in the art will appreciate that implementing all or part of the above described methods may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the various embodiments provided herein may include non-volatile and/or volatile memory. The nonvolatile memory can include Read Only Memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous Link DRAM (SLDRAM), memory bus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), among others.
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
It should be noted that, user information (including but not limited to user equipment information, user personal information, etc.) and data (including but not limited to data for presentation, analyzed data, etc.) referred to in the present application are information and data authorized by the user or sufficiently authorized by each party.
In this specification, each embodiment is described in a related manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, as relevant to see a section of the description of method embodiments.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples merely 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 invention. 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 (5)
1. A method of evaluating the brittleness of rock, the method comprising:
acquiring the peak strength, peak strain, elastic modulus and crack closure strain corresponding to the rock to be tested in a compression test;
determining the actual accumulation elastic energy before the peak and the accumulation strain energy in the ideal elastic deformation process before the peak corresponding to the rock to be tested according to the peak strength, the peak strain, the elastic modulus and the crack closure strain;
determining the ratio of the actual accumulation elastic energy before the peak to the accumulation strain energy in the ideal elastic deformation process before the peak as the accumulation rate of the elastic energy before the peak corresponding to the rock to be detected;
and determining the ratio of the pre-peak elastic energy accumulation rate to the peak strain as a brittleness evaluation index corresponding to the rock to be tested.
2. The method of claim 1, wherein determining the pre-peak actual accumulated elastic energy and the pre-peak ideal elastic deformation process accumulated strain energy corresponding to the rock to be tested based on the peak strength, the peak strain, the elastic modulus, and the crack closure strain comprises:
determining the actual accumulated elastic energy before the peak according to the peak strength and the elastic modulus;
and determining the ideal elastic deformation process accumulated strain energy before the peak according to the peak strain, the elastic modulus and the crack closure strain.
3. The method of claim 2, wherein the formula for determining the actual accumulated elastic energy before the peak from the peak intensity and the elastic modulus is:
wherein, W 1 indicating the actual accumulation of elastic energy before the peak,σ p the peak intensity is indicated as such,Ethe elastic modulus is shown.
4. The method of claim 2, wherein said determining said pre-peak ideal elastic deformation process accumulated strain energy from said peak strain, said elastic modulus, and said crack closure strain comprises:
determining the difference value of the peak strain and the crack closure strain as the deformation corresponding to the ideal elastic deformation process before the peak corresponding to the rock to be detected;
and determining accumulated strain energy in the ideal elastic deformation process before the peak according to the deformation amount corresponding to the ideal elastic deformation process before the peak and the elastic modulus.
5. The method of claim 4, wherein the equation for determining the accumulated strain energy for the pre-peak ideal elastic deformation process based on the amount of deformation corresponding to the pre-peak ideal elastic deformation process and the elastic modulus is:
wherein, W 2 indicating the ideal elastic deformation process before the peak accumulates strain energy,ε' represents the deformation corresponding to the ideal elastic deformation process before the peak,Ethe elastic modulus is shown.
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