CN111965032A - Mechanical damage analysis method for waste tailing cementing materials of tantalum-niobium ores with different proportions - Google Patents

Mechanical damage analysis method for waste tailing cementing materials of tantalum-niobium ores with different proportions Download PDF

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CN111965032A
CN111965032A CN202011063766.6A CN202011063766A CN111965032A CN 111965032 A CN111965032 A CN 111965032A CN 202011063766 A CN202011063766 A CN 202011063766A CN 111965032 A CN111965032 A CN 111965032A
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tantalum
acoustic emission
different proportions
fractal dimension
cementing material
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赵康
周昀
宋宇峰
严雅静
于祥
何志伟
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Jiangxi University of Science and Technology
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    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
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Abstract

The invention discloses a mechanical damage analysis method of tantalum-niobium ore waste tailing cementing materials with different proportions, which comprises the following steps of preparing tantalum-niobium ore waste tailing cementing material test pieces with different proportions; secondly, carrying out uniaxial compression test on the tantalum-niobium ore waste tailing cementing material test pieces with different proportions; thirdly, monitoring acoustic emission characteristic data of the tantalum-niobium ore waste tailing cementing material test pieces with different proportions in the whole compression process by adopting an acoustic emission system; and fourthly, calculating and analyzing the acoustic emission characteristic data by adopting a fractal dimension. The method disclosed by the invention is simple in steps, convenient to implement, good in analysis effect and convenient to popularize, and can be effectively applied to mechanical damage analysis of the tantalum-niobium ore waste tailing cementing material.

Description

Mechanical damage analysis method for waste tailing cementing materials of tantalum-niobium ores with different proportions
Technical Field
The invention belongs to the technical field of mine filling mining, and particularly relates to a mechanical damage analysis method for waste tailing cementing materials of tantalum-niobium ores with different proportions.
Background
A large amount of tailings are left after the tantalum-niobium ore is subjected to mineral separation, and a tailing pond needs to be built for storage. The method occupies a large amount of land, damages vegetation, causes harm to the surrounding environment, and causes deformation and damage of surrounding rocks in the goaf due to the fact that the original stress balance is broken through underground mining of the mine, causes roof collapse of the overlying strata and rib caving of the surrounding rocks, and brings serious influence to safety production of the mine. Therefore, the waste tailings after the mineral separation of the mine are made into a cementing material and filled underground, so that the deformation of surrounding rocks and a goaf top plate can be controlled, and rock burst and the falling of rock masses can be prevented; on the other hand, the method can also prevent ground surface geological disasters caused by movement and sinking of overlying strata in the goaf, and can also efficiently recycle the waste tailings sand to change waste into valuable. Therefore, the waste tailings are made into cement paste material backfill (CPB) for recycling, mineral resources can be exploited more cleanly, and the troublesome problems that the waste tailings are piled up, land on the ground is occupied, the environment is polluted and the like can be solved. The waste tailing filling technology is one of effective methods for solving the problems, and has positive effects on improving the economic benefit of the tantalum-niobium ore and on science and environmental protection. In order to effectively, safely and more environmentally utilize the mining method, it is necessary to research the mechanical properties and damage evolution process of the tantalum-niobium ore waste tailings as filling materials.
Acoustic emission signals in the process of filling body damage are complex and changeable, and regularity of the acoustic emission signals is difficult to find. Fractal theory is a new mathematical branch for researching the nonlinear problem, and the appearance of the fractal theory provides a powerful tool for people to research the rules hidden behind complex phenomena. It has been found that the physical-mechanical behavior of material deformation, failure, energy dissipation and propagation of internal microcracks all exhibit fractal characteristics. The acoustic emission signal generated along with the change of the internal structure of the material also has a fractal characteristic, and in the prior art, a fractal theory is used as a tool for researching the distribution rule of the acoustic emission signal in the process of the breakage of the filling body, and particularly an analysis method for searching the time sequence of the acoustic emission signal before the breakage of the filling body and the change characteristic (namely the breakage precursor information) of the signal is lacked.
Disclosure of Invention
The invention aims to solve the technical problem of providing a mechanical damage analysis method for tantalum-niobium ore waste tailing cementing materials with different proportions, which has the advantages of simple steps, convenient realization, effective application in the mechanical damage analysis of the tantalum-niobium ore waste tailing cementing materials, good analysis effect and convenient popularization.
In order to solve the technical problems, the invention adopts the technical scheme that: a mechanical damage analysis method for waste tailing cementing materials of tantalum-niobium ores with different proportions comprises the following steps:
firstly, manufacturing test pieces of tantalum-niobium ore waste tailing cementing materials with different proportions;
secondly, performing uniaxial compression test on the tantalum-niobium ore waste tailing cementing material test pieces with different proportions;
step three, monitoring acoustic emission characteristic data of the tantalum-niobium ore waste tailing cementing material test pieces with different proportions in a whole pressed process in real time by adopting an acoustic emission system;
step four, adopting fractal dimension to calculate and analyze the acoustic emission characteristic data;
step 401, calculating a fractal dimension;
step 402, determining a phase space dimension;
and step 403, analyzing the relation between the amplitude fractal characteristics and the damage.
According to the mechanical damage analysis method for the tantalum-niobium ore waste tailing cementing material with different proportions, in the step one, the manufacturing process of the tantalum-niobium ore waste tailing cementing material test piece with different proportions comprises the following steps: P.O32.5 ordinary portland cement is used as a cementing agent, different proportions of 1:4, 1:6, 1:8 and 1:10 of lime-sand ratio are adopted, the slurry concentration is 72%, a filling mould adopts a cylinder with the height of 100mm multiplied by phi 50mm, a standard constant-temperature curing box is used for curing for 28 days after 24-hour demoulding, and the humidity during curing is more than 96%.
In the mechanical damage analysis method for the tantalum-niobium ore waste tailing cementing material with different proportions, in the second step, the single-shaft compression test adopts an RMT-150C type hydraulic servo control system.
In the mechanical damage analysis method for the tantalum-niobium ore waste tailing cementing material with different proportions, the acoustic emission system in the third step adopts an American physical acoustic PCI-2 type multifunctional acoustic emission monitoring system.
In the third step, the process of monitoring the acoustic emission characteristic data of the tantalum-niobium ore waste tailing cementing material test pieces with different proportions in real time in the whole process of pressure by using an acoustic emission system comprises the following steps: the acoustic emission sensor in the PCI-2 type multifunctional acoustic emission monitoring system is placed close to the geometric symmetry center of the side face of a test block, vaseline is coated on the surface of a probe, signals are collected by two channels in a test, the main frequency is 120kHz, the parameter threshold is set to be 35DB, and the filter is set to be 20 k-100 kHz.
In the method for analyzing mechanical damage of the tantalum-niobium ore waste tailing cementing material with different proportions, the specific process for calculating the fractal dimension in the step 401 comprises the following steps:
step 4011, obtaining a time series data { x ] of the obtained test dataiEmbedding (i ═ 1,2 … N) into an m-dimensional Euclidean space RmObtaining a corresponding vector set J (m), wherein each element in the J (m) is as follows:
Xn(m,τ)＝(xn,xn+τ,…,xn+(m-1)×τ)，n＝1,2,…,Nm，
where τ ═ k Δ t denotes a fixed time interval, where Δ t denotes the time interval between two adjacent samples, k denotes a constant, N denotes a constantm＝N-(m-1)×τ；
Step 4012, in NmOptionally selecting a reference point X (i), and calculating the rest Nm-distance between 1 point and x (i):
Figure BDA0002713093080000031
wherein j is 1,2,3 … Nm；
Step 4013 for other Nm-1 point is operated according to step 4012 to obtain a correlation integral function:
Figure BDA0002713093080000032
in the formula, H represents a Heavi side function, and the value of H is as follows:
Figure BDA0002713093080000033
step 4014, passing formula
Figure BDA0002713093080000034
Calculating the Euclidean space RmThe relevance dimension d (m) of the included subset j (m);
step 4015, calculating AE correlation dimension values by using 50 AE time series data as a sampling unit, and obtaining the AE correlation dimension values by calculation when there are N acoustic emission time series data
Figure BDA0002713093080000041
Corresponding acoustic emission correlation fractal dimension value D2(i) Wherein, in the step (A),
Figure BDA0002713093080000042
step 4016, passing formula
Figure BDA0002713093080000043
Determining the size of the dimension m value;
step 4017, reconstructing the phase space of the AE time series parameters according to the m values, and calculating the distance r of each point in the phase spaceijAnd obtaining the maximum value r thereofij(max) and minimum value rij(min) and according to the formula
Figure BDA0002713093080000044
The distance r is obtained by calculationijStep Δ r of (d);
step 4018, r is respectively pairedijAnd Cm(r) logarithmic and run at lnrijAs abscissa lnCm(r) is a vertical coordinate, a straight line is obtained through linear fitting, and the slope of the straight line is the related fractal dimension value D of the cementing material test piece2(i)。
In the method for analyzing mechanical damage of the tantalum-niobium ore waste tailing cementing material with different proportions, the specific process for determining the phase space dimension in step 402 comprises the following steps: calculating the AE parameters obtained in the instability destruction process of the cementing material test piece under uniaxial compression, and drawing the associated fractal dimension value D2(i) And the phase space dimension m.
In the method for analyzing the mechanical damage of the tantalum-niobium ore waste tailing cementing material with different proportions, the specific process of analyzing the amplitude fractal characteristics and the damage relation in the step 403 comprises the following steps: and taking acoustic emission parameter data acquired in 50 tests as a unit, calculating an acoustic emission amplitude associated fractal dimension value, drawing a related fractal dimension value, time and stress relation curve graph, and averaging the associated fractal dimension values of the cement material test piece.
In the method for analyzing the mechanical damage of the cemented material of the abandoned tailings of the tantalum-niobium ores with different proportions, the process of averaging the associated fractal dimension values of the cemented material test piece comprises the step of averaging the associated fractal dimension values within each 10% stress level range, and a relation curve graph with the stress level as a horizontal coordinate and the average fractal dimension value as a vertical coordinate is drawn.
Compared with the prior art, the invention has the following advantages:
1. the method has simple steps and convenient realization.
2. According to the method, the tantalum-niobium ore waste tailing cementing material is manufactured and maintained, the tantalum-niobium ore waste tailing cementing material test pieces with different proportions are obtained, then a uniaxial compression test and real-time monitoring of an acoustic emission system are carried out on the tantalum-niobium ore waste tailing cementing material test pieces, and acoustic emission characteristic data of the cementing material test pieces are obtained.
3. The fractal dimension is adopted to calculate and analyze the acoustic emission characteristic data, and the variation trend that the acoustic emission fractal dimension values are reduced simultaneously when the cemented material test piece is unstably damaged is combined to be used as a precursor basis for damage and damage of the cemented material test piece, so that a practical reference value is provided for safety monitoring of filling a mine goaf with the tantalum-niobium ore waste tailings, and theoretical data are provided for recycling mine wastes, reducing surface emission and pollution and reducing the influence of mining activities on the surface ecological environment.
4. The method can be effectively applied to mechanical damage analysis of the tantalum-niobium ore waste tailing cementing material, has a good analysis effect, and is convenient to popularize.
In conclusion, the method provided by the invention is simple in steps, convenient to implement, good in analysis effect and convenient to popularize, and can be effectively applied to mechanical damage analysis of the tantalum-niobium ore waste tailing cementing material.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
FIG. 1 is a flow chart of a method of the present invention;
FIG. 2 is a graph of a relationship between an associated fractal dimension value and a phase space dimension according to the present invention;
FIG. 3 is a graph of an amplitude-correlated fractal dimension curve and an average fractal dimension value of a cementitious material test piece according to the invention, wherein the ratio of ash to sand is 1: 4;
FIG. 4 is a graph of an amplitude-correlated fractal dimension curve and an average fractal dimension value of a cementitious material test piece according to the invention, wherein the ratio of ash to sand is 1: 6;
FIG. 5 is a graph of an amplitude-correlated fractal dimension curve and an average fractal dimension value of a cementitious material test piece according to the invention, wherein the ratio of ash to sand is 1: 8;
FIG. 6 is a graph of the amplitude correlation fractal dimension and the average fractal dimension value of the cement test piece with a 1:10 ratio of ash to sand.
Detailed Description
As shown in fig. 1, the method for analyzing mechanical damage of the cemented material of the discarded tailings of tantalum-niobium ores with different proportions comprises the following steps:
firstly, manufacturing test pieces of tantalum-niobium ore waste tailing cementing materials with different proportions;
secondly, performing uniaxial compression test on the tantalum-niobium ore waste tailing cementing material test pieces with different proportions;
step three, monitoring acoustic emission characteristic data of the tantalum-niobium ore waste tailing cementing material test pieces with different proportions in a whole pressed process in real time by adopting an acoustic emission system;
step four, adopting fractal dimension to calculate and analyze the acoustic emission characteristic data;
step 401, calculating a fractal dimension;
step 402, determining a phase space dimension;
and step 403, analyzing the relation between the amplitude fractal characteristics and the damage.
In the method, the specific manufacturing process of the tantalum-niobium ore waste tailing cemented body with different proportions in the step one comprises the following steps: P.O32.5 ordinary portland cement is used as a cementing agent, different proportions of 1:4, 1:6, 1:8 and 1:10 of lime-sand ratio are adopted, the slurry concentration is 72%, a filling mould adopts a cylinder with the height of 100mm multiplied by phi 50mm, a standard constant-temperature curing box is used for curing for 28 days after 24-hour demoulding, and the humidity during curing is more than 96%.
In specific implementation, the cement material test pieces with the ash-sand ratio of 1:4 are numbered as E1, E2 and E3, the cement material test pieces with the ash-sand ratio of 1:6 are numbered as F1, F2 and F3, the cement material test pieces with the ash-sand ratio of 1:8 are numbered as G1, G2 and G3, and the cement material test pieces with the ash-sand ratio of 1:10 are numbered as H1, H2 and H3.
In the method, the single-shaft compression test in the step two adopts an RMT-150C type hydraulic servo control system.
In the method, the acoustic emission system in the third step adopts an American physical acoustic PCI-2 type multifunctional acoustic emission monitoring system.
In the third step, the concrete process of monitoring the acoustic emission characteristic data of the abandoned tailing cemented body of the tantalum-niobium ore with different proportions in the whole compression process by adopting an acoustic emission system in real time comprises the following steps: in the third step, the process of monitoring the acoustic emission characteristic data of the tantalum-niobium ore waste tailing cementing material test pieces with different proportions in real time by adopting an acoustic emission system in the whole process of pressing comprises the following steps: the acoustic emission sensor in the PCI-2 type multifunctional acoustic emission monitoring system is placed close to the geometric symmetry center of the side face of a test block, vaseline is coated on the surface of a probe, signals are collected by two channels in a test, the main frequency is 120kHz, the parameter threshold is set to be 35DB, and the filter is set to be 20 k-100 kHz.
In the method, the specific process of calculating the fractal dimension in step 401 includes:
step 4011, obtaining a time series data { x ] of the obtained test dataiEmbedding (i ═ 1,2 … N) into an m-dimensional Euclidean space RmObtaining a corresponding vector set J (m), wherein each element in the J (m) is as follows:
Xn(m,τ)＝(xn,xn+τ,…,xn+(m-1)×τ)，n＝1,2,…,Nm，
where τ ═ k Δ t denotes a fixed time interval, where Δ t denotes the time interval between two adjacent samples, k denotes a constant, N denotes a constantm＝N-(m-1)×τ；
In specific implementation, Δ t is 4, and k is 15.
Step 4012, in NmOptionally selecting a reference point X (i), and calculating the rest Nm-distance between 1 point and x (i):
Figure BDA0002713093080000071
wherein j is 1,2,3 … Nm；
Step 4013 for other Nm-1 point is operated according to step 4012 to obtain a correlation integral function:
Figure BDA0002713093080000072
in the formula, H represents a Heavi side function, and the value of H is as follows:
Figure BDA0002713093080000073
step 4014, passing formula
Figure BDA0002713093080000074
Calculating the Euclidean space RmThe relevance dimension d (m) of the included subset j (m);
step 4015, calculating AE correlation dimension values by using 50 AE time series data as a sampling unit, and obtaining the AE correlation dimension values by calculation when there are N acoustic emission time series data
Figure BDA0002713093080000081
Corresponding acoustic emission correlation fractal dimension value D2(i) Wherein, in the step (A),
Figure BDA0002713093080000082
step 4016, passing formula
Figure BDA0002713093080000083
Determining the size of the dimension m value;
in specific implementation, as can be seen from the above formula, D is increased gradually2(i) The value will approach a relatively stable value, and the corresponding m value is the m value to be selected.
Step 4017, reconstructing the phase space of the AE time series parameters according to the m-value, and calculating the phase space of each pointDistance rijAnd obtaining the maximum value r thereofij(max) and minimum value rij(min) and according to the formula
Figure BDA0002713093080000084
The distance r is obtained by calculationijStep Δ r of (d);
step 4018, r is respectively pairedijAnd Cm(r) logarithmic and run at lnrijAs abscissa lnCm(r) is a vertical coordinate, a straight line is obtained through linear fitting, and the slope of the straight line is the related fractal dimension value D of the cementing material test piece2(i)。
In the method, the specific process for determining the phase space dimension in step 402 includes: calculating the AE parameters obtained in the instability destruction process of the cementing material test piece under uniaxial compression, and drawing the associated fractal dimension value D2(i) And the phase space dimension m.
In specific implementation, as shown in fig. 2, the magnitude of the associated fractal dimension value changes to some extent along with the value of the phase space dimension m, but the "self-similarity" of the acoustic emission parameter is not affected, and the magnitude of the phase space dimension m does not affect the change trend of the associated fractal dimension value, but only affects the magnitude of the associated fractal dimension value. When the phase space dimension is between 2 and 4, the associated fractal dimension value curve approaches to a straight line, and therefore, the value of the phase space dimension m is selected to be 4.
In the method, the specific process of analyzing the relationship between the amplitude fractal feature and the damage in step 403 includes: and taking acoustic emission parameter data acquired in 50 tests as a unit, calculating an acoustic emission amplitude associated fractal dimension value, drawing a related fractal dimension value, time and stress relation curve graph, and averaging the associated fractal dimension values of the cement material test piece.
In the method, the process of averaging the associated fractal dimension values of the cement material test piece comprises averaging the associated fractal dimension values within each 10% stress level range, and drawing a relation curve graph with the stress level as a horizontal coordinate and the average fractal dimension value as a vertical coordinate.
In specific implementation, when the associated fractal dimension value is continuously reduced, the sequential degree of the AE process of the cemented material test piece is gradually improved, and the large-scale damage is mainly applied to the interior of the cemented material test piece in the instability damage process. When the associated fractal dimension value has a rising trend, the acoustic emission process of the cementing material test piece is shown to evolve towards a chaotic state, and at the moment, the inside of the cementing material test piece mainly takes the small-scale microcracks as a main part. The associated fractal dimension values of the cement test pieces are required to be averaged because the curve peaks of the associated fractal dimension values of the cement test pieces are dense and complicated and the change rules of the curve are difficult to distinguish.
As shown in fig. 3, the amplitude-correlated fractal dimension curves and the average fractal dimension value curves of the test pieces E1, E2 and E3 show that: in the initial compaction stage, namely before the stress level is 20%, the amplitude correlation fractal dimension values of the cement test piece are all at a higher level, which is caused by the fact that the internal pores of the test piece are compacted in the initial compaction stage and the scale of the initiated microcracks is smaller. And then, along with the increase of the stress, the fractal dimension value of the test piece gradually decreases and is in a descending trend, which shows that large-scale microcracks in the test piece begin to appear and gradually increase, and the acoustic emission signals also gradually tend to be ordered, wherein the average fractal dimension value of the E2 test piece is rapidly reduced to the minimum value of 1.85 from 2.21 at the stage. When the stress continues to increase, in the range of 30-60% of the stress level, namely the elastic stage of the cementing material test piece, the fractal dimension values of the test pieces E1 and E3 have large fluctuation range, microcracks with different sizes in the internal dimensions of the test pieces are alternately generated, the acoustic emission amplitude self-similarity of the test pieces is low on the whole, wherein the average fractal dimension of the test piece E1 reaches the minimum value in the range of 50-60% of the stress level, which indicates that the microcrack size of the test piece is increased; and after the fractal dimension value of the E2 test piece is subjected to the minimum value at this stage, the fractal dimension value shows a continuously rising trend, which indicates that small-scale cracks of the test piece are gradually increased, the acoustic emission order is gradually weakened, and the self-similarity is also reduced.
As shown in fig. 4, it can be known from the correlation fractal dimension value-time-stress curve and the average fractal dimension value-stress percentage curve that before the stress level reaches 20%, the AE signals of the test pieces F2 and F3 are very few in the early stage of this stage, and no acoustic emission fractal dimension value exists in the corresponding correlation fractal dimension value curve at this stage, that is, before the stress level reaches 10%; then along with the increase of stress, AE fractal dimension value appears at 10% -20%, and the AE fractal dimension value shows a slow descending trend until the stage is finished, which indicates that the internal pores of the test piece are gradually compacted; the acoustic emission fractal dimension value of the F1 test piece has a tendency of continuously descending from the beginning of the test, and the descending speed is faster than that of the F2 test piece and the F3 test piece, which shows that the compaction degree of the F1 test piece is higher at the stage, and the internal microcrack of the F1 test piece is also faster in initiation speed. Along with the continuous increase of the stress, in the range of 30-70% of the stress level, a linear elasticity stage is corresponding to the stress level, the AE fractal dimension value of the test piece has larger volatility, the F1 test piece fractal dimension value is in a generally descending trend in the stage, and only a small amplitude is increased at about 40% of the stress level until the stress level reaches a minimum value between 60-70%. The large-scale microcracks in the test piece are gradually increased, the occupied proportion is also increased, and the order and the self-similarity of AE signals are also gradually enhanced; the fractal dimension values of the F2 and F3 test pieces are complicated to change at this stage, and microcracks with different internal dimensions of the test pieces are alternately generated, so that the AE amplitude self-similarity is reduced. When the stress level is between 80-90% and 70-80%, fractal dimension values of F2 and F3 test pieces respectively reach the minimum value, which indicates that large-scale macroscopic cracks are generated in the cementing material test piece at the moment, and indicates that the test piece is about to be seriously damaged; and finally, the fractal dimension value of the test piece rises again, which shows that the large-scale crack of the test piece is further expanded and communicated until the test piece is completely damaged.
As shown in fig. 5, the fractal dimension values of the test pieces G1 and G2 show a tendency of gradually rising or gradually falling in the overall manner that the amplitude of the fluctuation is relatively regular until the stress level is 60%. The acoustic emission signal sequence of the G1 test piece is gradually reduced in the stress level, the self-similarity is weakened, and microcracks with different sizes in the test piece are continuously generated, so that a small part of the test piece is subjected to microcracking; in contrast, the AE fractal dimension value orderliness of the G2 test piece is gradually enhanced in the stress level, the self-similarity is also improved, microcracks with different sizes in the test piece are alternately generated, but the large-scale microcracks are mainly generated, and the proportion of the large-scale microcracks is gradually increased along with the time; before the stress level of the G3 test piece is 30%, the acoustic emission fractal dimension value of the test piece gradually and slowly increases, which shows that the micro-cracks in the test piece are mainly small-scale at the stage, the initiation and the expansion of the micro-cracks are stable, and then the acoustic emission fractal dimension value suddenly and rapidly decreases until the minimum value is reached within 40-50% of the stress level; the method shows that sudden large cracking cracks appear in the test piece, and the order degree and the self-similarity of the acoustic emission of the test piece are rapidly enhanced in a short time. The acoustic emission fractal dimension values of the G1 and G2 test pieces all show a sharp descending trend between the stress level of 60% and the stress peak value, and reach the minimum value at the stage, so that the micro cracks in the test pieces are further expanded and run through to form the macro cracks; the fractal dimension value of the G3 test piece shows a continuously rising trend after reaching the minimum value, the acoustic emission signal of the test piece gradually changes from ordered to disordered, the self-similarity of the acoustic emission signal is gradually weakened, and the microcracks in the filling body are continuously expanded, extended and communicated so that the filling body is finally and completely destroyed; after the fractal dimension values of the test pieces G1 and G2 reach the minimum value, the process is similar to that of the test piece G3.
As shown in fig. 6, the AE fractal dimension values of 3 cement test pieces with a 1:10 ash-to-sand ratio all showed a decreasing trend before the stress level was 20%, except that the decreasing speed was different; the fractal dimension value of the H1 test piece is reduced more slowly, and the fractal dimension value of the H3 test piece is reduced more quickly, which may be related to the degree of compaction inside the test piece, and the reduction of the fractal dimension value indicates that large-scale micro cracks are generated inside the test piece, and at the moment, the test piece is slightly damaged. Then the H1 test piece has repeated fluctuation of 'descending-ascending' in the form dimension value within the stress level of 30-70 percent, and the fluctuation is large; however, the fractal dimension value of the test piece is in a descending trend on the whole, the AE orderliness is also improved, and the fractal dimension is at the minimum value at the stage, which indicates that the test piece is about to be damaged. The fractal dimension value of the H2 test piece keeps a continuously descending trend all the time in the stress level and reaches a minimum value in the stress level of 70-80%. In the process, the AE fractal dimension value greatly improves the AE orderliness and the self-similarity, the large-scale microcracks in the test piece are gradually increased, and the microcracks are continuously expanded and communicated, so that the test piece is damaged. The fractal dimension value of the H3 test piece shows a rising trend in the stress level, which shows that the test piece is mainly a small-scale micro-crack, and the acoustic emission signal is relatively weak in order. After the stress level is 70%, fractal dimension values of H1 and H2 test pieces quickly rise, cracks of different scales in the test pieces continue to expand and penetrate, and the proportion of large-scale cracks is gradually increased, so that the test pieces are completely destabilized and damaged; the fractal dimension value of the H3 test piece is sharply reduced from the maximum value to the minimum value at this stage, which indicates that the large-scale microcrack in the test piece develops very quickly, and the propagation and through evolution processes of the microcrack are very violent, indicating that the test piece is about to be damaged.
By synthesizing the acoustic emission amplitude fractal characteristic analysis of the waste tailing cemented test piece with different ratios of sand to ash under the condition of uniaxial compression, the following results can be found: the acoustic emission fractal characteristics of the cemented material test piece are analyzed and researched by data obtained by uniaxial compression acoustic emission test of the tantalum-niobium ore tailing cemented material test piece with the ash-sand ratio of 1:4, 1:6, 1:8 and 1:10, and the following conclusion can be obtained:
(1) most of the correlation coefficients of the acoustic emission amplitudes of the cement material test pieces with different gray-sand ratios are above 0.85 in the instability destruction process, which shows that the energy rate fractal characteristics and the amplitude fractal characteristics of the test pieces in the destruction process are high in significance. Before the stress level is 20%, the acoustic emission fractal dimension value of the test piece with different dust-sand ratios basically has the slow descending trend; the acoustic emission fractal dimension value has large fluctuation amplitude within the stress level range of 30-90%, but still shows a descending change trend on the whole.
(2) Before the stress level is 30%, the amplitude fractal dimension values of the cement test pieces with different sand-lime ratios generally show a descending trend. The minimum amplitude fractal dimension is mostly concentrated in the stress level range of 70% to 90%. In the stage close to the stress peak value, the amplitude fractal dimension value has the tendency of rising again. The minimum value of the amplitude fractal dimension is more concentrated, which shows that the judgment of the fractal dimension on the cement material test piece is more accurate when the cement material test piece is unstably damaged. Therefore, the instability damage effect of the cementing material test piece monitored by the amplitude fractal dimension value is better.
(3) In the loaded process of the waste filling body, the acoustic emission correlation fractal dimension changes along with the change of the stress level, which shows that the self-similarity degree of the acoustic emission process is different under different stress states. Therefore, like the mechanical parameters of the filling body, such as stress, strain and the like, the associated fractal function of the acoustic emission process can also be used as a characteristic parameter for describing the mechanical characteristics of the material. The combination of the change trend that the acoustic emission fractal dimension values are reduced simultaneously when the test piece is unstable and damaged can be used as a precursor basis for damage and damage of the filling body, and a practical reference value is provided for safety monitoring of filling the mine goaf by adopting the tantalum-niobium ore waste tailings. The method provides demonstration for recycling mine wastes, reducing surface discharge and pollution and reducing the influence of mining activities on the surface ecological environment.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, changes and equivalent structural changes made to the above embodiment according to the technical spirit of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims (9)

1. A mechanical damage analysis method for waste tailing cementing materials of tantalum-niobium ores with different proportions is characterized by comprising the following steps: the method comprises the following steps:
firstly, manufacturing test pieces of tantalum-niobium ore waste tailing cementing materials with different proportions;
secondly, performing uniaxial compression test on the tantalum-niobium ore waste tailing cementing material test pieces with different proportions;
step three, monitoring acoustic emission characteristic data of the tantalum-niobium ore waste tailing cementing material test pieces with different proportions in a whole pressed process in real time by adopting an acoustic emission system;
step four, adopting fractal dimension to calculate and analyze the acoustic emission characteristic data;
step 401, calculating a fractal dimension;
step 402, determining a phase space dimension;
and step 403, analyzing the relation between the amplitude fractal characteristics and the damage.
2. The mechanical damage analysis method for the tantalum-niobium ore waste tailing cementing material with different proportions according to claim 1 is characterized in that: the manufacturing process of the tantalum-niobium ore waste tailing cementing material test piece with different proportions in the step one comprises the following steps: P.O32.5 ordinary portland cement is used as a cementing agent, different proportions of 1:4, 1:6, 1:8 and 1:10 of lime-sand ratio are adopted, the slurry concentration is 72%, a filling mould adopts a cylinder with the height of 100mm multiplied by phi 50mm, a standard constant-temperature curing box is used for curing for 28 days after 24-hour demoulding, and the humidity during curing is more than 96%.
3. The mechanical damage analysis method for the tantalum-niobium ore waste tailing cementing material with different proportions according to claim 1 is characterized in that: and step two, the single-shaft compression test adopts an RMT-150C type hydraulic servo control system.
4. The mechanical damage analysis method for the tantalum-niobium ore waste tailing cementing material with different proportions according to claim 1 is characterized in that: and in the third step, the acoustic emission system adopts an American physical acoustic PCI-2 type multifunctional acoustic emission monitoring system.
5. The mechanical damage analysis method for the tantalum-niobium ore waste tailing cementing material with different proportions according to claim 4 is characterized in that: in the third step, the process of monitoring the acoustic emission characteristic data of the tantalum-niobium ore waste tailing cementing material test pieces with different proportions in real time by adopting an acoustic emission system in the whole process of pressing comprises the following steps: the acoustic emission sensor in the PCI-2 type multifunctional acoustic emission monitoring system is placed close to the geometric symmetry center of the side face of a test block, vaseline is coated on the surface of a probe, signals are collected by two channels in a test, the main frequency is 120kHz, the parameter threshold is set to be 35DB, and the filter is set to be 20 k-100 kHz.
6. The mechanical damage analysis method for the tantalum-niobium ore waste tailing cementing material with different proportions according to claim 1 is characterized in that: the specific process of calculating the fractal dimension in step 401 includes:
step 4011, obtaining a time series data { x ] of the obtained test dataiEmbedding (i ═ 1,2 … N) into an m-dimensional Euclidean space RmObtaining a corresponding vector set J (m), wherein each element in the J (m) is as follows:
Xn(m,τ)＝(xn,xn+τ,…,xn+(m-1)×τ)，n＝1,2,…,Nm，
where τ ═ k Δ t denotes a fixed time interval, where Δ t denotes the time interval between two adjacent samples, k denotes a constant, N denotes a constantm＝N-(m-1)×τ；
Step 4012, in NmOptionally selecting a reference point X (i), and calculating the rest Nm-distance between 1 point and x (i):
Figure FDA0002713093070000021
wherein j is 1,2,3 … Nm；
Step 4013 for other Nm-1 point is operated according to step 4012 to obtain a correlation integral function:
Figure FDA0002713093070000022
in the formula, H represents a Heaviside function, and the value of H is as follows:
Figure FDA0002713093070000023
step 4014, passing formula
Figure FDA0002713093070000024
Calculating the Euclidean space RmThe relevance dimension d (m) of the included subset j (m);
step 4015, calculating AE correlation dimension values by using 50 AE time series data as a sampling unit, and obtaining the AE correlation dimension values by calculation when there are N acoustic emission time series data
Figure FDA0002713093070000025
Corresponding acoustic emission correlation fractal dimension value D2(i) Wherein, in the step (A),
Figure FDA0002713093070000031
step 4016, passing formula
Figure FDA0002713093070000032
Determining the size of the dimension m value;
step 4017, reconstructing the phase space of the AE time series parameters according to the m values, and calculating the distance r of each point in the phase spaceijAnd obtaining the maximum value r thereofij(max) and minimum value rij(min) and according to the formula
Figure FDA0002713093070000033
The distance r is obtained by calculationijStep Δ r of (d);
step 4018, r is respectively pairedijAnd Cm(r) logarithmic and run at lnrijAs abscissa lnCm(r) is a vertical coordinate, a straight line is obtained through linear fitting, and the slope of the straight line is the related fractal dimension value D of the cementing material test piece2(i)。
7. The mechanical damage analysis method for the tantalum-niobium ore waste tailing cementing material with different proportions according to claim 6 is characterized in that: the specific process of determining the spatial dimension in step 402 includes: calculating the AE parameters obtained in the instability destruction process of the cementing material test piece under uniaxial compression, and drawing the associated fractal dimension value D2(i) And the phase space dimension m.
8. The mechanical damage analysis method for the tantalum-niobium ore waste tailing cementing material with different proportions according to claim 7 is characterized in that: the specific process of analyzing the relationship between the amplitude fractal feature and the damage in step 403 includes: and taking acoustic emission parameter data acquired in 50 tests as a unit, calculating an acoustic emission amplitude associated fractal dimension value, drawing a related fractal dimension value, time and stress relation curve graph, and averaging the associated fractal dimension values of the cement material test piece.
9. The mechanical damage analysis method for the tantalum-niobium ore waste tailing cementing material with different proportions according to claim 8 is characterized by comprising the following steps of: the process of averaging the associated fractal dimension values of the cement material test piece comprises the step of averaging the associated fractal dimension values within each 10% stress level range, and the step of drawing a relation curve graph with the stress level as a horizontal coordinate and the average fractal dimension value as a vertical coordinate.
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