Underground surrounding rock overall stability evaluation method based on deformation uniformity coefficient

Abstract

The invention provides an underground surrounding rock overall stability evaluation method based on a deformation uniformity coefficient, and the method comprises the following steps: S1, building a three-dimensional geologic model of an engineering region, and obtaining a deformation release rate diagram of nodes in surrounding rock under different excavation sequences through numerical simulation calculation; s2, calculating a deformation uniformity coefficient of the node according to the envelope area; s3, marking as a global deformation uniformity coefficient, and evaluating the stability of the surrounding rock according to the global deformation uniformity coefficient; and S4, according to the design scheme, the mining sequence is replaced, the steps S1 to S3 are repeated, the global deformation uniformity coefficient of the excavation sequence under each excavation sequence is obtained, and according to the global deformation uniformity coefficient number value and the sequence, the excavation scheme with the maximum deformation uniformity coefficient value is the optimal surrounding rock stability. According to the method, the influence of the excavation sequence on the deformation path is considered, the surrounding rock stability evaluation method of the deformation uniformity coefficient is provided, and the accuracy and reliability of scheme optimization by a numerical calculation result can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of underground engineering surrounding rock stability evaluation, and in particular to a method for evaluating the overall stability of underground surrounding rock based on deformation uniformity coefficient. Background Art

[0002] During underground engineering excavation, different excavation sequences will cause different deformation distribution patterns of the surrounding rock and different settlement deformations of the surface. Since the final state of the excavation area is the same, it is difficult to consider the impact of the excavation path on the stability of the surrounding rock during the numerical calculation process, resulting in little difference in conventional evaluation indicators such as deformation, stress, and plastic zone of the surrounding rock under different excavation sequences, generally with a difference of 1 to 5%, making it difficult to accurately evaluate the stability of the surrounding rock under various excavation sequences.

[0003] Existing research CN: 34-1055 / TD "Research on Optimization of Structural Parameters and Mining Sequence of Deep Mining Field in Xincheng Gold Mine" uses finite element numerical simulation calculation method to compare the maximum displacement and plastic zone of six schemes including four structural parameters and two mining sequences of deep mining field in Xincheng Gold Mine during the mining period, and obtains the optimal structural parameters of the deep mining field.

[0004] Existing research CN: 43-1104 / TD "Dynamic simulation selection of reasonable mining sequence in the middle section of Sanshandao gold mine", the surrounding rock stress and displacement conditions under sequence, provides technical support for the safe and efficient recovery of ore resources on the seabed of the mining area.

[0005] However, the above studies did not consider the impact of the shape path of surrounding rock release on the stability of surrounding rock during numerical analysis, resulting in small differences between the final displacement and stress values ​​of the evaluation indicators of surrounding rock stability, and the judgment results of displacement stress could not reach a consensus, such as one scheme calculated large displacement and small stress while another scheme calculated small displacement and large stress. It is impossible to directly give the optimal solution based on the calculation results, and it is difficult to effectively evaluate the differences in the stability of surrounding rock caused by various mining sequences. The deformation uniformity coefficient can be directly compared by drawing images to solve the deformation uniformity coefficient value, directly linking the stability of surrounding rock to the coefficient value, and intuitively judging the stability of surrounding rock. Summary of the invention

[0006] The purpose of the present invention is to propose a method for evaluating the overall stability of underground surrounding rocks based on deformation uniformity coefficient, so as to solve the problem that the current method for evaluating the overall stability of underground surrounding rocks does not consider the rock deformation release path, resulting in inaccurate evaluation results.

[0007] The technical means adopted by the present invention are as follows:

[0008] A method for evaluating the overall stability of underground surrounding rock based on deformation uniformity coefficient comprises the following steps:

[0009] S1. Use FLAC3D software to establish a three-dimensional geological model of the underground engineering area. According to the rock mass properties of the underground engineering area, the mechanical models and calculation parameters of different rock properties in the three-dimensional geological model are given through parametric language. Based on FLAC3D, numerical calculations are carried out for different excavation sequence conditions of underground engineering. The deformation values ​​of each node in the surrounding rock under different excavation sequences are obtained by calculation. According to the deformation values ​​and different excavation sequences, the deformation release rate diagram of each node is obtained;

[0010] S2. Superimpose the deformation release rate diagram with the optimal mining path rate diagram to obtain the envelope area of ​​the deformation path and the constant speed path of each node in the surrounding rock under different excavation sequence conditions, and calculate the deformation uniformity coefficient of each node according to the envelope area;

[0011] S3, statistically analyzing the deformation uniformity coefficient of each node in the three-dimensional geological model, and calculating the average deformation uniformity coefficient of all nodes, recording it as the global deformation uniformity coefficient, and evaluating the surrounding rock stability of the excavation sequence working condition according to the global deformation uniformity coefficient;

[0012] S4. Change the excavation sequence and repeat S1 to S3 to obtain the global deformation uniformity coefficient under each excavation sequence condition; compare the global deformation uniformity coefficient under the excavation sequence condition to be evaluated. The closer the global deformation uniformity coefficient is to 1, the better the surrounding rock stability is and the most reasonable excavation sequence is; the closer the global deformation uniformity coefficient is to 0, the worst the surrounding rock stability is and the excavation sequence is the worst option.

[0013] Furthermore, in S2, the calculation formula of the deformation uniformity coefficient is as follows:

[0014]

[0015] Among them, μ is the deformation uniformity coefficient; S is the envelope area.

[0016] Furthermore, in S3, the calculation formula for the uniformity coefficient of surrounding rock deformation in the global stope is as follows:

[0017]

[0018] in, It is the cumulative value of the deformation uniformity coefficient μ of the first to the Nth mining schemes to be evaluated, and N is the total number of mining schemes to be evaluated.

[0019] Furthermore, in S1, the steps of solving the FLAC model are as follows:

[0020] The FLAC3D geological model is established according to the underground engineering geological information, excavation sequence, and specific dimensions; the constraint boundary conditions of the FLAC3D geological model are determined according to the burial depth and the distribution law of the ground stress field; the model equilibrium state is established and the model response is checked; the calculation conditions are established by adjusting different excavation sequences, and the FLAC3D model under different excavation sequence conditions is solved to obtain the surrounding rock deformation values ​​under different conditions.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] The evaluation method of the present invention solves the problem that the influence of the excavation path on the surrounding rock deformation is not considered in the existing stability evaluation method by introducing the deformation uniformity coefficient of the deformation release path, thereby improving the accuracy of the numerical analysis of the surrounding rock stability and the operability of the users. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 Schematic diagram of the method of the present invention.

[0025] Figure 2 It is a step diagram for implementing the present invention.

[0026] Figure 3 This is a diagram of the static analysis solution process based on numerical calculation software of the present invention.

[0027] Figure 4 It is a comparison diagram of the deformation release rate diagram of the present invention and the rate diagram of the optimal mining path.

[0028] Figure 5 Graph showing deformation uniformity coefficient according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0030] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0031] A method for evaluating the overall stability of underground surrounding rock based on deformation uniformity coefficient, such as Figure 1 and 2 As shown, the following steps are included:

[0032] S1: Figure 3 As shown in the figure, according to the actual situation of the underground engineering, FLAC3D is used to establish a three-dimensional geological model of the engineering area. The model is solved step by step according to the mining sequence of an existing scheme. The deformation of the nodes in the surrounding rock is obtained through the result data of each loading step. According to the deformation value and different excavation sequences, the deformation release rate diagram of each node is obtained; at the same time, it is set that when the deformation rate of the stope reaches a constant deformation release rate, the mining path is the optimal mining path.

[0033] The steps for solving the FLAC3D model are as follows: establish a FLAC3D geometric model based on underground engineering geological information, excavation sequence, and specific dimensions; determine the constraint boundary conditions of the FLAC3D geometric model based on the burial depth and the distribution law of the ground stress field; establish the model equilibrium state and check the model response; establish calculation conditions by adjusting different excavation sequences, solve the FLAC3D model under different excavation sequence conditions, and obtain the surrounding rock deformation values ​​under different conditions.

[0034] S2: Compare the deformation release rate diagram of the scheme with the rate diagram of the optimal mining path, such as Figure 4 As shown in the figure, the envelope area of ​​the deformation path of the scheme and the constant uniform deformation route is set to S. The larger the envelope area, the greater the difference from the optimal path. In order to accurately and uniformly quantify the deformation uniformity coefficient, the envelope area S is normalized. If N mining sequences are designed, there will be N deformation release paths. Then the area enclosed by the Nth deformation path and the optimal path with an ideal constant deformation release rate is recorded as S. N, where the largest envelope area among the N deformation paths is selected as the reference value, and the ratio of other areas to this value is normalized. The normalized ratio is then subtracted from 1, and this value is the coefficient of deformation uniformity. The expression of the deformation uniformity coefficient of the Nth mining method can be found in Formula 1:

[0035]

[0036] The deformation uniformity coefficient of a point in different mining methods can be calculated. N is the deformation uniformity coefficient of the Nth method; S N is the envelope area in the Nth method.

[0037] S3: After obtaining the deformation uniformity coefficient of the surrounding rock nodes under a certain excavation sequence, in order to evaluate the stability of the surrounding rock of the entire underground project, the deformation uniformity coefficients of all nodes in the model are accumulated and finally divided by the number of accumulations to obtain the surrounding rock full giant deformation uniformity coefficient, which is used to evaluate the overall stability of the surrounding rock under this mining sequence. For details, see Formula 2.

[0038]

[0039] in, It is the cumulative value of the deformation uniformity coefficient μ from the first method to the Nth method, and N is the total number of mining methods.

[0040] S4: By repeating the above steps, the global deformation uniformity coefficient ε of other mining methods can be obtained through numerical calculation and formula calculation. By comparing this coefficient ε, the surrounding rock stability of the excavation sequence working condition can be evaluated.

[0041] The closer the final ε is to 1, the closer it is to the optimal mining path. Conversely, the greater the gap between the stress release path and the optimal path. The closer the coefficient is to 1, the more stable the deformation release rate is, which is beneficial to the stability of the surrounding rock. On the contrary, the closer the coefficient is to 0, the greater the fluctuation of the deformation release rate is, which is more unfavorable to the stability of the surrounding rock. This coefficient index can be used to evaluate the stability of the surrounding rock under different excavation sequences, so as to optimize the actual engineering excavation sequence and ensure the best deformation release path for the surrounding rock.

[0042] Through experimental proof and engineering application, when the deformation uniformity coefficient is ≥0.75, the deformation release of the surrounding rock during excavation is relatively stable and the surrounding rock stability is good; when the deformation uniformity coefficient is 0-0.5, the surrounding rock stability is relatively poor.

[0043] Example

[0044] Surrounding rock stability evaluation method for coordinated mining of multiple stopes in an underground mine:

[0045] S1. Use FLAC3D software to establish a three-dimensional geological model of the mine panel and stope, and assign the Mohr-Coulomb constitutive model and corresponding calculation parameters to it through parametric language according to the properties of the ore body. Model size: 665mx1160mx758m. Boundary conditions: Displacement constraints are imposed on the boundaries around the model and the bottom boundary, and corresponding ground stress is applied to the model according to the measured ground stress data.

[0046] σ H =-0.0454×h-4.14 (1)

[0047] σv=-0.027×h (2)

[0048] σ h =-0.0259×h+2.11 (3)

[0049] In the formula, σ H is the maximum horizontal principal stress, MPa; σ h is the minimum horizontal principal stress, MPa; σ v is the vertical principal stress, MPa; h is the drilling depth, m.

[0050] Calculation parameters: The parameters of surrounding rock, ore body, etc. are assigned according to the data obtained in the aforementioned indoor rock mechanics test as shown in Table 1; the first-step cemented filling body is assigned according to the lime-sand ratio of 1:4, and the second-step cemented filling body is assigned according to the lime-sand ratio of 1:10.

[0051] Table 1 Physical and mechanical parameters of rock mass

[0052]

[0053] The model meshes the designed mining range of the ore body (elevation -580m to -100m, west of the 10# exploration line), with the minimum unit size of 5m. The grid of the surrounding rock area is progressively enlarged, and the maximum unit size is 130m. A total of 2251561 grid units and 1291661 grid nodes are generated. Based on the FLAC3D calculation method, numerical calculations are carried out for different mining sequences between the upper and lower single-stage mining methods: one mining every other, one mining every other, and one mining every three mining sequences, and different mining sequences between the upper and lower two-stage simultaneous mining methods: one mining every other, one mining every other, and one mining every three mining sequences. The deformation values ​​of the surrounding rock in different excavation sequences are obtained by calculation, and the deformation release rate diagram of each node is obtained according to the deformation value and different mining sequence.

[0054] S2. Calculate the first mining sequence among the six mining sequences, record the deformation value of each node in the surrounding rock, extract the displacement value to draw a deformation release rate diagram, and calculate the envelope area of ​​the deformation release rate diagram and the constant speed route.

[0055] Table 2 Displacement values ​​of surrounding rock roof in different mining methods

[0056]

[0057]

[0058] S3. By counting the deformation uniformity coefficient of each node in the three-dimensional geological model and calculating the average deformation uniformity coefficient of all nodes, it can be obtained that the global deformation uniformity coefficient of the surrounding rock is 0.72 in the single-stage mining mode and the mining sequence of every other mining.

[0059] S4. Repeat S1-S3 to calculate the global deformation uniformity coefficient of the surrounding rock under the other five mining sequences. It is found that the deformation uniformity coefficient of the two-stage three-mining method is 0.85, and the deformation uniformity coefficient of the single-stage three-mining method is 0.82. Compared with other mining schemes, the deformation uniformity coefficients of the two are closer to 1. The closer to the optimal mining path, the more stable, and more conducive to the uniform release of surrounding rock deformation, which is conducive to the stability of the surrounding rock during the mining process. The global deformation uniformity coefficients of each mining scheme are shown in Figure 5 , the displacement of surrounding rock top plate at each stage is shown in Table 2.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the overall stability of underground surrounding rock based on deformation uniformity coefficient, characterized in that: The steps include: S1. Use FLAC3D software to establish a three-dimensional geological model of the underground engineering area. According to the rock mass properties of the underground engineering area, the mechanical models and calculation parameters of different rock properties in the three-dimensional geological model are given through parametric language. Based on FLAC3D, numerical calculations are carried out for different excavation sequence conditions of underground engineering. The deformation values ​​of each node in the surrounding rock under different excavation sequences are obtained by calculation. According to the deformation values ​​and different excavation sequences, the deformation release rate diagram of each node is obtained; S2. Superimpose the deformation release rate diagram with the optimal mining path rate diagram to obtain the envelope area of ​​the deformation path and the constant speed path of each node in the surrounding rock under different excavation sequence conditions, and calculate the deformation uniformity coefficient of each node according to the envelope area; S3, statistically analyzing the deformation uniformity coefficient of each node in the three-dimensional geological model, and calculating the average deformation uniformity coefficient of all nodes, recording it as the global deformation uniformity coefficient, and evaluating the surrounding rock stability of the excavation sequence working condition according to the global deformation uniformity coefficient; S4. Change the excavation sequence and repeat S1 to S3 to obtain the global deformation uniformity coefficient under each excavation sequence condition; compare the global deformation uniformity coefficient under the excavation sequence condition to be evaluated. The closer the global deformation uniformity coefficient is to 1, the better the surrounding rock stability is and the most reasonable excavation sequence is; the closer the global deformation uniformity coefficient is to 0, the worst the surrounding rock stability is and the excavation sequence is the worst option.

2. The method for evaluating the overall stability of underground surrounding rock based on deformation uniformity coefficient according to claim 1 is characterized in that: In S2, the calculation formula of deformation uniformity coefficient is as follows: Among them, μ is the deformation uniformity coefficient; S is the envelope area.

3. The method for evaluating the overall stability of underground surrounding rock based on deformation uniformity coefficient according to claim 1 is characterized in that: In S3, the calculation formula of the global deformation uniformity coefficient of surrounding rock is as follows: in, It is the cumulative value of the deformation uniformity coefficient μ from the first method to the Nth excavation sequence, and N is the total number of excavation sequences to be evaluated.

4. The method for evaluating the overall stability of underground surrounding rock based on deformation uniformity coefficient according to claim 1, characterized in that: In S1, the steps to solve the FLAC model are as follows: Establish FLAC3D geological model based on underground engineering geological information, excavation sequence and specific dimensions; The constraint boundary conditions of the FLAC3D geological model are determined according to the burial depth and the distribution law of the ground stress field; the equilibrium state of the model is established and the model response is checked; the calculation conditions are established by adjusting different excavation sequences, and the FLAC3D model under different excavation sequence conditions is solved to obtain the surrounding rock deformation values ​​under different conditions.

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