Numerical simulation method for long-term surface deformation induced by underground mining

Abstract

The invention discloses a numerical simulation method for long-term surface deformation induced by underground mining based on the compaction process of a caving zone, comprising: obtaining geological survey data, modeling a study area according to the geological survey data, and obtaining a numerical calculation model; determining the calculation parameters of the numerical calculation model; simulating the step-by-step excavation of the coal seam to be mined, and calculating the instantaneous surface settlement caused by coal seam mining; simulating the compaction process of the broken rock mass in the caving zone; after simulating the compaction process of the broken rock mass in the caving zone, obtaining a first corresponding relationship between the residual settlement of the surface of the goaf and the time of suspension of mining; obtaining a second corresponding relationship between the strength of the broken rock mass in the caving zone and time according to the first corresponding relationship, wherein the second corresponding relationship reflects the long-term surface deformation process induced by underground mining. The method has the characteristics of convenient modeling, short test cycle and low economic cost, and can actually reflect the long-term surface deformation of the goaf.

Description

Technical Field

[0001] The invention relates to the field of in-situ testing and indoor testing of rock mass mechanics, and in particular to a numerical simulation method for long-term surface deformation induced by underground mining based on a compaction process of a caving zone. Background Art

[0002] Coal has long been the main energy source in my country and is related to the country's economic lifeline and energy security. The mining and utilization of coal has played a huge role in promoting my country's economic and social development. However, coal mining has made the surface of the coal mining area a concentration of goaf areas, and the negative impact of mining subsidence on engineering construction and the ecological environment cannot be ignored. my country has a vast territory, but the available land resources are still relatively scarce. The emergence of a large number of goafs has exacerbated the problem of land resource utilization. With the rapid development of social economy, it is inevitable to carry out engineering construction above the goaf. Evaluating the long-term stability of the surface of the goaf is a top priority to ensure the safety of engineering construction. Therefore, it is urgent to carry out research on long-term surface deformation induced by underground mining.

[0003] The main methods for studying the long-term deformation of the surface of goaf areas include theoretical analysis, empirical estimation, physical model test, field monitoring and numerical simulation. Numerical simulation can not only save a lot of manpower and material resources and make up for the shortcomings of insufficient observation data, but also analyze the influence of various geological factors. Therefore, it is widely used in the study of long-term deformation of the surface of goaf areas.

[0004] In the numerical simulation study of long-term deformation of the surface of the goaf, the long-term deformation of the overlying rock mass in the goaf is usually simplified to the creep deformation of the complete rock block. In fact, the long-term deformation of the surface of the goaf is mainly caused by the filling and compaction of the broken rock mass in the caving zone. Figure 1 As shown in the figure, the broken rock mass in the caving zone collapses irregularly and fills the goaf. Under the pressure of the overlying strata, the broken rock mass is continuously compacted, causing long-term deformation of the goaf surface. Therefore, the numerical simulation method of long-term deformation of the goaf surface used in the relevant technology cannot actually reflect the long-term deformation of the goaf surface. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, one purpose of the present invention is to propose a numerical simulation method for long-term surface deformation induced by underground mining based on the compaction process of the caving zone. The method simulates the compaction process of the broken rock mass in the caving zone by replacing the parameters of the broken rock mass in the caving zone, and obtains the long-term deformation law of the surface. The method has the characteristics of convenient modeling, short test cycle and low economic cost, and can actually reflect the long-term deformation of the surface of the goaf. It has important theoretical and application value for evaluating the long-term stability of the surface induced by underground mining.

[0006] To achieve the above-mentioned purpose, the first embodiment of the present invention proposes a numerical simulation method for long-term surface deformation induced by underground mining based on the compaction process of the caving zone, and the method includes the following steps: obtaining geological survey data, and modeling the study area according to the geological survey data to obtain a numerical calculation model; determining the calculation parameters of the numerical calculation model; simulating the step-by-step excavation of the coal seam to be mined, and calculating the instantaneous surface settlement caused by coal seam mining according to the calculation parameters; simulating the compaction process of the broken rock mass in the caving zone; after simulating the compaction process of the broken rock mass in the caving zone, obtaining a first corresponding relationship between the residual settlement of the surface of the goaf and the mining suspension time; according to the first corresponding relationship, obtaining a second corresponding relationship between the strength of the broken rock mass in the caving zone and time, wherein the second corresponding relationship reflects the long-term surface deformation process induced by underground mining.

[0007] According to the numerical simulation method of underground mining-induced long-term surface deformation based on the compaction process of the caving zone according to the embodiment of the present invention, the study area is modeled by geological survey data to obtain a numerical calculation model.

[0008] The compaction process of the broken rock mass in the caving zone is simulated according to the numerical calculation model. After the simulation of the compaction process of the broken rock mass in the caving zone, the corresponding relationship between the strength of the broken rock mass in the caving zone and time is obtained. The long-term deformation process of the surface induced by underground mining is reflected according to the corresponding relationship. This method has the characteristics of convenient modeling, short test cycle and low economic cost, and can actually reflect the long-term deformation of the surface of the goaf. It has important theoretical and application value for evaluating the long-term stability of the surface induced by underground mining.

[0009] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A schematic diagram of compaction of broken rock mass in the caving zone after coal seam mining according to one embodiment of the present invention;

[0011] Figure 2 A flowchart of a numerical simulation method for long-term surface deformation induced by underground mining based on the compaction process of the caving zone according to an embodiment of the present invention;

[0012] Figure 3 A numerical calculation model diagram of long-term surface deformation caused by coal seam mining according to an embodiment of the present invention;

[0013] Figure 4 A morphological diagram of a surface subsidence basin before replacement parameters after 3# coal mining according to an embodiment of the present invention;

[0014] Figure 5A morphological diagram of a surface subsidence basin at various broken rock mass parameter levels after 3# coal is mined and parameters are replaced according to an embodiment of the present invention;

[0015] Figure 6 A morphological diagram of a surface subsidence basin at various broken rock mass parameter levels after 15# coal is mined and the parameters are replaced according to an embodiment of the present invention;

[0016] Figure 7 It is a schematic diagram of the deformation of the opening of the cut before the 15# coal replacement parameters according to an embodiment of the present invention;

[0017] Figure 8 It is a schematic diagram of deformation of the opening of the cutting hole after the 15# coal replacement parameters according to an embodiment of the present invention;

[0018] Fig. 9 A schematic diagram of the middle cavity of the goaf before the 15# coal replacement parameters according to an embodiment of the present invention;

[0019] Fig.10 A schematic diagram of filling the middle cavity of the goaf after 15# coal replacement parameters according to an embodiment of the present invention;

[0020] Fig.11 It is a schematic diagram of deformation at the stop line before the 15# coal replacement parameters according to an embodiment of the present invention;

[0021] Fig.12 It is a schematic diagram of deformation at the stop-mining line after the 15# coal replacement parameters according to one embodiment of the present invention;

[0022] Fig.13 A graph showing the accumulated residual settlement of the ground surface according to an embodiment of the present invention;

[0023] Fig.14 FIG. 1 is a graph showing changes in mechanical parameters of a broken rock mass over time according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0025] The following describes a numerical simulation method for long-term surface deformation induced by underground mining based on the compaction process of the caving zone according to an embodiment of the present invention with reference to the accompanying drawings.

[0026] Figure 2 The flowchart of the numerical simulation method of long-term surface deformation induced by underground mining based on the compaction process of the caving zone according to one embodiment of the present invention is shown in FIG. Figure 2 As shown, the numerical simulation method includes the following steps:

[0027] S101, obtaining geological survey data, and modeling the study area according to the geological survey data to obtain a numerical calculation model.

[0028] S102, determining calculation parameters of the numerical calculation model.

[0029] S103, performing step-by-step excavation simulation on the coal seam to be mined, and calculating the instantaneous surface settlement caused by coal seam mining according to calculation parameters.

[0030] It should be noted that in the numerical calculation model, the coal seams to be excavated may include the first coal seam and the second coal seam, wherein when the second coal seam is mined, the surface residual settlement caused by the mining of the first coal seam has been completed.

[0031] Specifically, the coal seams to be excavated are the first coal seam and the second coal seam from top to bottom, for example, the 3# coal and the second coal seam 15# coal, and the mining time interval is 25 years. Based on this, it is determined that when the lower 15# coal is mined, the surface residual settlement caused by the mining of 3# coal has been completed. Therefore, in the simulation, 3# coal is excavated first, and after the excavation is completed, the caving zone parameters of the 3# coal seam are modified to the broken rock parameters. After the compaction calculation is completed, 15# coal is excavated, and after the excavation is completed, the caving zone parameters of the 15# coal seam are modified to the broken rock parameters, so as to more realistically reflect the mining process.

[0032] In one embodiment of the present invention, the planned mining length of the working face is a first preset length, the thickness of the first coal seam is a first thickness, and the thickness of the second coal seam is a second thickness. When simulating the step-by-step excavation of the first coal seam and the second coal seam, the second preset length is mined in one step, wherein the second preset length is smaller than the first preset length.

[0033] Specifically, based on the stratigraphic structure profile and drilling data in the geological survey data, a working face with a mining length of about 1000m can be selected, and a section can be taken along the mining direction for two-dimensional plane calculation. Figure 3 As shown, the mineable coal seams from top to bottom in the numerical calculation model are 3# coal in the first coal seam and 15# coal in the second coal seam, among which the thickness of 3# coal can be 2m, and the thickness of 15# coal can be 6m. The length direction of the numerical calculation model is the mining direction of the working face, that is, the X-axis direction, and the height direction of the numerical calculation model is the burial depth direction of the coal seam, that is, the Y-axis direction. Among them, the numerical calculation model is divided into quadrilateral grids, with a total of 17157 units. The calculation boundary is a displacement constraint boundary condition, the X-axis direction is a normal displacement constraint, and the bottom of the Y-axis direction is an omnidirectional displacement constraint. The dead weight of the rock mass is considered in the calculation, and the gravity acceleration in the numerical calculation model is taken as 9.80m / s 2, thus, the numerical calculation model in step S101 is established.

[0034] Furthermore, the calculation parameters in the numerical calculation model can be determined by combining indoor experiments and engineering analogies, as shown in the calculation parameter value table in Table 1 below.

[0035] Table 1

[0036]

[0037]

[0038] Further, in step S103, when simulating the step-by-step excavation of the coal seam to be mined, firstly, the 3# coal is mined step by step, and the second preset length, such as 10m, is mined in one step. After the 3# coal is mined, the surface subsidence basin morphology is as follows: Figure 4 As shown in the figure. Since the surface is mountainous, the surface subsidence basin shows a slightly undulating shape. At this time, the surface basin has a clear outline, indicating that full mining has been achieved. Figure 4 As shown, the maximum surface subsidence is 1.8m and the subsidence coefficient reaches 0.9.

[0039] S104, simulates the compaction process of the broken rock mass in the caving zone.

[0040] In one embodiment of the present invention, simulating the compaction process of broken rock mass in the caving zone may include: determining the height of the caving zone and the mechanical parameters of the broken rock mass in the caving zone; selecting n groups of target replacement parameter levels within the range of the parameter level of the broken rock mass in the caving zone to the parameter level of the original rock mass in the caving zone, wherein n≥10 and is a positive integer; within the range of the height of the caving zone, replacing the mechanical parameters of the broken rock mass in the caving zone in sequence from strong to weak with n groups of target replacement parameter levels for calculation, so as to simulate the compaction process of the broken rock mass in the caving zone.

[0041] Among them, determining the height of the caving zone may include: when the mining area has detailed geological data and measured data, comprehensively determining the height of the caving zone based on the detailed data of the mining area; when the mining area has no measured data, determining the height of the caving zone with reference to the measured data of the mining area with similar geological conditions; when the mining area has neither measured data nor projects with similar geological conditions to the mining area, calculating the height of the caving zone according to regulations based on the overburden type.

[0042] As an example, when there is neither measured data nor a mining area with similar mining conditions for reference, the height of the caving zone in the mining area can be calculated according to the "Specifications for Coal Pillar Retention and Compression Mining in Buildings, Water Bodies, Railways and Main Shafts and Tunnels" (2017), as shown in Table 2 below, for example, about 5m, and its length is consistent with the length range of the goaf.

[0043] Table 2

[0044]

[0045] Among them, ΣM is the cumulative mining thickness, and the ± items in the calculation formula are the mean error. The application range of the above formula is single-layer mining thickness of 1 to 3 meters, and the cumulative mining thickness does not exceed 15 meters.

[0046] In one embodiment of the present invention, determining the mechanical parameters of the broken rock mass in the caving zone may include: when the mining area has in-situ test data of the broken rock mass in the caving zone of the goaf, determining the mechanical parameters of the broken rock mass in the caving zone according to the in-situ test data; when the mining area does not have in-situ test data of the broken rock mass in the caving zone of the goaf, but has indoor test data of the broken rock mass in the caving zone of the goaf, determining the mechanical parameters of the broken rock mass in the caving zone according to the indoor test data of the broken rock mass; when both of the above two conditions are not met, determining the mechanical parameters of the broken rock mass in the caving zone with reference to the in-situ test or indoor test data of the broken rock mass in the caving zone of the mining area with similar geological conditions; when all three of the above conditions are not met, determining the mechanical parameters of the broken rock mass in the caving zone of the goaf according to the compaction test data of the broken rock mass in other documents.

[0047] As an example, when there is no in-situ test data of the broken rock mass in the caving zone of the goaf in a mining area, but there is indoor test data of the broken rock mass in the caving zone of the goaf, the minimum parameter level of the broken rock mass can be obtained through indoor compaction test of the broken rock mass, which is elastic modulus E=0.2GPa, Poisson's ratio μ=0.4, cohesion c=0, and the internal friction angle φ is the same as that of the original rock mass.

[0048] In one embodiment of the present invention, simulating the compaction process of broken rock mass in the caving zone may further include: when mining 3# coal in the first coal seam, selecting 10 sets of target replacement parameter levels within the range of the parameter level of the broken rock mass in the caving zone to the parameter level of the original rock mass in the caving zone; when mining 15# coal in the second coal seam, selecting 50 sets of target replacement parameter levels within the range of the parameter level of the broken rock mass in the caving zone to the parameter level of the original rock mass in the caving zone.

[0049] Specifically, when mining the first coal seam 3# coal, 10 groups of target replacement parameter levels are selected on average within the range from the parameter level of the broken rock mass in the caving zone to the parameter level of the original rock mass in the caving zone, and they are sorted from strong to weak, and can be named level1, level2, level3...level10. After the coal seam excavation calculation is completed, the mechanical parameters of the broken rock mass in the caving zone can be replaced with the level 1 level for calculation on the numerical calculation model after the excavation. After the level 1 calculation is completed, the mechanical parameters of the broken rock mass in the caving zone are replaced from the level 1 level to the level 2 level for calculation. By analogy, the mechanical parameters of the broken rock mass in the caving zone are replaced step by step from level 1 to level 10 to simulate the compaction process of the broken rock mass. Among them, the morphology of the surface subsidence basin under each parameter level is as follows: Figure 5 shown.

[0050] Similarly, when excavating 15# coal, after adopting the method of steps S101-S103, 50 groups of target replacement parameter levels can be selected on average within the range of the broken rock mass parameter level in the caving zone to the original rock mass parameter level in the caving zone, such as level 1, level 2, ..., level 50, and the mechanical parameters of the broken rock mass in the caving zone are replaced step by step with the target replacement parameter level on the numerical calculation model after excavation. Among them, the morphology of the surface subsidence basin under each parameter level is as follows: Figure 6 As shown in the figure. After the 15# coal mining is completed and the mechanical parameters of the broken rock mass in the caving zone are replaced, not only the broken rock mass in the caving zone is compacted, but also the voids generated by mining are gradually filled with the broken rock mass in the caving zone. After the compaction process calculation is completed, the voids at the opening and stop mining line are basically completely disappeared. Take the 15# coal goaf area as an example. Figure 7 to Figure 12 The deformation conditions at different positions of the goaf are shown before and after the mechanical parameters of the broken rock mass in the caving zone were replaced after the mining of 15# coal was completed.

[0051] S105, after simulating the compaction process of the broken rock mass in the caving zone, a first corresponding relationship between the residual settlement on the surface of the goaf and the mining suspension time is obtained.

[0052] In one embodiment of the present invention, a first correspondence between the residual settlement on the surface of the goaf and the time of suspension of mining is obtained, including: obtaining a cumulative residual settlement curve and a measured residual settlement curve, wherein the cumulative residual settlement curve is a relationship curve between the cumulative compaction amount of the surface residual settlement and the parameters of the broken rock mass in the caving zone; the cumulative residual settlement curve is compared with the measured residual settlement curve to obtain the first correspondence.

[0053] Wherein, obtaining the cumulative residual settlement curve may include calculating the difference between the surface settlement amounts after two adjacent replacements, and accumulating all the differences to obtain the cumulative residual settlement curve.

[0054] Specifically, because the mining interval between 3# coal and 15# coal is 25 years, when the lower 15# coal is mined, the residual ground subsidence caused by 3# coal mining has been completed. Therefore, in this example, only the long-term ground deformation induced by 15# coal mining is concerned. Figure 6 As shown in the figure, during the numerical simulation of the compaction of the broken rock mass in the caving zone of the 15# coal goaf area, as the strength of the rock mass parameters in the caving zone gradually decreases, the surface settlement becomes larger and larger. However, in the actual coal mining process, due to the gradual compaction of the broken rock mass in the caving zone, the change of the rock mass parameters in the caving zone is from weak to strong. In order to describe this process, the lowest parameter level level 50 can be set as the initial lowest parameter level of the caving zone. At this time, the surface residual settlement is 0m. As the parameter level increases (level50, level49, ..., level1), the surface settlement gradually increases, and the settlement is the difference between the surface settlements calculated at two adjacent parameter levels. By adding up the settlement differences under each adjacent parameter level, we can get Fig.13 The relationship curve between the cumulative compaction amount of surface residual settlement and the parameters of the broken rock mass in the caving zone is the cumulative residual settlement curve. Fig.13 As shown in the figure, after the mining of No. 15 coal was completed and the parameters were replaced, the maximum residual settlement of the ground surface was 0.21m. If the mechanical parameters of the broken rock mass were continued to increase, the surface settlement would no longer change, indicating that the limit state of the broken rock mass had been reached.

[0055] Furthermore, the measured residual settlement curve can be obtained based on the measured surface settlement data. The fitting formula for the long-term surface deformation after the mining area is stopped is:

[0056] s=210.909(1-e -0.280484t ) (1)

[0057] Where s represents the accumulated residual settlement in mm, and t represents the time in years. Substituting time t from year 0 into the above formula (1), the accumulated residual settlement of the surface in each year is obtained as shown in Table 3.

[0058] Table 3

[0059]

[0060]

[0061] Furthermore, the calculated cumulative residual settlement curve can be compared with the measured residual settlement curve to obtain the corresponding relationship between the residual settlement value on the surface of the goaf and the mining suspension time, that is, the first corresponding relationship.

[0062] S106, obtaining a second corresponding relationship between the strength of the broken rock mass in the caving zone and time based on the first corresponding relationship, wherein the second corresponding relationship reflects the long-term deformation process of the surface induced by underground mining.

[0063] In one embodiment of the present invention, a second corresponding relationship between the strength of the broken rock mass in the caving zone and time is obtained based on the first corresponding relationship, including: obtaining a third corresponding relationship between the mechanical parameters of the broken rock mass in the caving zone and time based on the first corresponding relationship; obtaining the ratio of the strength parameters of the broken rock mass corresponding to different mining suspension times to the strength parameters of the original rock before mining; and normalizing the mechanical parameters of the broken rock mass in the caving zone in the third relationship based on the ratio to obtain the second corresponding relationship.

[0064] Among them, according to the third corresponding relationship between the mechanical parameters of the broken rock mass in the caving zone and time, the mechanical parameters of the broken rock mass in the caving zone corresponding to different years can be obtained. Then, according to the ratio of the strength parameters of the broken rock mass corresponding to different mining suspension times to the strength parameters of the original rock mass before mining, the mechanical parameters of the broken rock mass in the caving zone are normalized to obtain Fig.14 The second corresponding relationship between the strength of the broken rock mass in the caving zone and time is shown. Since the parameters of the broken rock mass in the caving zone are further enhanced, but the surface settlement no longer increases, it shows that the parameters of the broken rock mass are restored to 98% of the original rock mass at most. Therefore, according to the second corresponding relationship between the strength of the broken rock mass in the caving zone and time, the strength change of the broken rock mass in the caving zone can be used to characterize the compaction process of the broken rock mass in the caving zone under the pressure of the overlying strata, so as to reflect the long-term deformation process of the surface induced by underground mining, and of course, it can also provide a scientific basis for other similar engineering calculations.

[0065] According to the numerical simulation method of underground mining-induced long-term surface deformation based on the compaction process of the caving zone according to the embodiment of the present invention, the study area is modeled by geological survey data to obtain a numerical calculation model.

[0066] The compaction process of the broken rock mass in the caving zone is simulated by replacing the parameters of the broken rock mass in the caving zone. After the simulation of the compaction process of the broken rock mass in the caving zone, the corresponding relationship between the strength of the broken rock mass in the caving zone and time is obtained. According to the corresponding relationship, the long-term deformation process of the surface induced by underground mining is reflected. This method has the characteristics of convenient modeling, short test cycle and low economic cost, and can actually reflect the long-term deformation of the surface of the goaf. It has important theoretical and application value for evaluating the long-term stability of the surface induced by underground mining.

[0067] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or otherwise processing in a suitable manner if necessary, and then stored in a computer memory.

[0068] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0069] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0070] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0071] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A numerical simulation method for long-term surface deformation induced by underground mining based on the compaction process of the caving zone, characterized in that: The following steps are involved: Acquire geological survey data, and model the study area based on the geological survey data to obtain a numerical calculation model; Determining calculation parameters of the numerical calculation model; Simulating the excavation of the coal seam to be mined in steps, and calculating the instantaneous ground settlement caused by coal seam mining according to the calculation parameters; Simulate the compaction process of broken rock mass in the caving zone; After simulating the compaction process of the broken rock mass in the caving zone, the first corresponding relationship between the residual settlement of the goaf surface and the mining suspension time was obtained; A second corresponding relationship between the strength of the broken rock mass in the caving zone and time is obtained according to the first corresponding relationship, wherein the second corresponding relationship reflects the long-term deformation process of the ground surface induced by underground mining; The first corresponding relationship between the residual settlement on the surface of the goaf and the mining suspension time is obtained, including: Obtaining a cumulative residual settlement curve and a measured residual settlement curve, wherein the cumulative residual settlement curve is a relationship curve between the cumulative compaction amount of surface residual settlement and the broken rock mass parameters of the caving zone; Comparing the cumulative residual settlement curve with the measured residual settlement curve to obtain the first corresponding relationship; The second corresponding relationship between the strength of the broken rock mass in the caving zone and the time is obtained according to the first corresponding relationship, including: According to the first corresponding relationship, a third corresponding relationship between the mechanical parameters of the broken rock mass in the caving zone and time is obtained; Obtain the ratio of the strength parameter of the broken rock mass corresponding to different mining suspension times to the strength parameter of the original rock before mining; The mechanical parameters of the broken rock mass in the caving zone in the third corresponding relationship are normalized according to the ratio to obtain a second corresponding relationship.

2. The numerical simulation method for long-term surface deformation induced by underground mining based on the compaction process of the caving zone according to claim 1 is characterized in that: The compaction process of the simulated caving zone broken rock mass includes: Determine the height of the caving zone and the mechanical parameters of the broken rock mass in the caving zone; In the range from the parameter level of the broken rock mass in the caving zone to the parameter level of the original rock mass in the caving zone, n groups of target replacement parameter levels are selected, where n is ≥ 10 and is a positive integer; Within the height range of the caving zone, the mechanical parameters of the broken rock mass in the caving zone are replaced with n groups of target replacement parameter levels in sequence from strong to weak, so as to simulate the compaction process of the broken rock mass in the caving zone.

3. The numerical simulation method for long-term surface deformation induced by underground mining based on the compaction process of the caving zone according to claim 1 is characterized in that: In the numerical calculation model, the coal seams to be mined include a first coal seam and a second coal seam, wherein when the second coal seam is mined, the surface residual settlement caused by the mining of the first coal seam has been completed.

4. The numerical simulation method for long-term surface deformation induced by underground mining based on the compaction process of the caving zone according to claim 3 is characterized in that: In the numerical calculation model, the planned mining length of the working face is a first preset length, the thickness of the first coal seam is a first thickness, and the thickness of the second coal seam is a second thickness. When simulating the step-by-step excavation of the first coal seam and the second coal seam, the second preset length is mined in one step, wherein the second preset length is smaller than the first preset length.

5. The numerical simulation method for long-term surface deformation induced by underground mining based on the compaction process of the caving zone according to claim 3 is characterized in that: The method comprises: When mining the first coal seam, 10 groups of target replacement parameter levels are selected within the range from the parameter level of the broken rock mass in the caving zone to the parameter level of the original rock mass in the caving zone; When mining the second coal seam, 50 sets of target replacement parameter levels are selected within the range from the parameter level of the broken rock mass in the caving zone to the parameter level of the original rock mass in the caving zone.

6. The numerical simulation method for long-term surface deformation induced by underground mining based on the compaction process of the caving zone according to claim 1 is characterized in that: The step of obtaining the cumulative residual sedimentation curve comprises: Calculate the difference between the surface settlement after two adjacent replacements; All the differences are accumulated to obtain the cumulative residual sedimentation curve.

7. The numerical simulation method for long-term surface deformation induced by underground mining based on the compaction process of the caving zone according to claim 2 is characterized in that: Determining the height of the caving zone comprises: When there are detailed geological data and measured data for the mining area, the height of the caving zone is comprehensively determined based on the detailed data of the mining area; When there is no measured data for the mining area, the height of the caving zone is determined by referring to the measured data of the mining area with similar geological conditions; When there is neither measured data nor a project with geological conditions similar to the mining area, the height of the caving zone shall be calculated in accordance with regulations based on the overburden type.

8. The numerical simulation method for long-term surface deformation induced by underground mining based on the compaction process of the caving zone according to claim 2 is characterized in that: The method of determining the mechanical parameters of the broken rock mass in the caving zone includes: When the mining area has in-situ test data of the broken rock mass in the caving zone of the goaf, the mechanical parameters of the broken rock mass in the caving zone are determined according to the in-situ test data; When the mining area does not have in-situ test data of the broken rock mass in the caving zone of the goaf, but has indoor test data of the broken rock mass in the caving zone of the goaf, the mechanical parameters of the broken rock mass in the caving zone are determined according to the indoor test data of the broken rock mass; When both of the above conditions are not met, the mechanical parameters of the broken rock mass in the caving zone shall be determined by referring to the in-situ test data of the broken rock mass in the caving zone with geological conditions similar to those in the mining area or the indoor test data; When the above three conditions are not met, the mechanical parameters of the broken rock mass in the caving zone of the goaf are determined based on the compaction test data of the broken rock mass in other literature.

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