Deeply buried BIF type iron ore layered ore body stope structure parameter design method

Abstract

The invention discloses a deep-buried BIF type iron ore layered ore body stope structure parameter design method, and relates to the technical field of mining methods. The method comprises the following steps: determining a crustal stress state of an ore body; determining the bedding state of the ore body; determining a spatial relationship between a crustal stress state and a bedding state, and constructing a three-dimensional ore body model; on the basis of the three-dimensional ore body model, a stope is arranged in the bedding direction perpendicular to the ore body; determining influence factors of stress and bedding on the length of the stope and influence factors of stress and bedding on the width of the stope; and correcting the length of the stope according to the influence factor of the length of the stope, and correcting the width of the stope according to the influence factor of the width of the stope. According to the method, the influence of the combined action of ground stress and bedding on the stability of the rock mass is considered, the stope stability can be effectively improved, and the safety and efficiency of the stoping process are guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mining methods, in particular to a method for designing structural parameters of a stope of a deep buried BIF type iron ore bedded ore body. BACKGROUND

[0002] Stope structure and parameter design is an important factor to determine the safety of mine production. Especially with the increase of mining depth, the ground stress increases, and the high ground stress condition in deep part puts forward higher requirements for the structure and parameter design of the stope. The stope structure design and parameter selection need to fully consider the influence of ground stress on rock mass stability.

[0003] Among deep iron ore resources, the BIF (Banded Iron Formation) type iron ore with huge deposit size is the most important type of iron ore deposit. In terms of structure and construction, the components of the BIF type iron ore are mostly fine-grained, and the main minerals such as quartz and iron oxides appear in the form of iron-silicon alternating banded thin layers. Therefore, the BIF type iron ore body is layered, and its mechanical properties have strong anisotropy characteristics.

[0004] The stope structure and parameter design of deep buried BIF type iron ore need to consider the influence of deep buried high stress on the stability of bedded rock mass. The current method for designing the structure and parameters of deep stope often only considers the influence of ground stress on the parameters of the stope, and ignores the influence of ground stress on the structure of the stope, especially the influence of the combined action of ground stress and bedding on the structure and parameters of the stope.

[0005] In view of the above problems existing in the prior art, the technical personnel in the field urgently need a method for designing the structural parameters of a stope of a deep buried BIF type iron ore bedded ore body.

[0006] The above information disclosed in the background of the application is only used to increase the understanding of the background of the application, and therefore, it can include prior art known by those skilled in the art. SUMMARY

[0007] The purpose of the present application is to provide a method for designing the structural parameters of a stope of a deep buried BIF type iron ore bedded ore body, to solve the above problems existing in the prior art, to consider the influence of the combined action of ground stress and bedding on rock mass stability, and to effectively improve the stability of the stope and ensure the safety and efficiency of the recovery process.

[0008] To achieve the above purpose, the present application provides the following solutions:

[0009] The application provides a method for designing structural parameters of a stope of a deep-buried BIF type iron ore bedded ore body, comprising the following steps: determining a ground stress state of the ore body; determining a bedding state of the ore body; determining a spatial relationship between the ground stress state and the bedding state and constructing a three-dimensional ore body model; arranging a stope along a bedding direction of the ore body on the basis of the three-dimensional ore body model; determining an influence factor of stress and bedding on a length of the stope and an influence factor of stress and bedding on a width of the stope; correcting the length of the stope according to the influence factor of the length of the stope and correcting the width of the stope according to the influence factor of the width of the stope; wherein the ground stress state of the ore body comprises a size and a direction of a horizontal maximum principal stress, a size and a direction of a horizontal minimum principal stress and a size and a direction of a vertical principal stress, and the bedding state of the ore body comprises a bedding direction of the ore body.

[0010] In some embodiments, the step of determining the influence factor of stress and bedding on the length of the stope and the influence factor of stress and bedding on the width of the stope comprises: performing a true triaxial loading and unloading test according to the ground stress state, the bedding state of the stope and a stress path change after excavation of the stope to determine the influence factor of stress and bedding on the length of the stope and the influence factor of stress and bedding on the width of the stope.

[0011] In some embodiments, the step of performing the true triaxial loading and unloading test according to the bedding state of the stope and the stress path change after excavation of the stope comprises: sampling a true triaxial sample from the ore body and processing the true triaxial sample into a true triaxial sample with the same bedding state as the stope; loading the true triaxial sample to an in-situ stress state according to the ground stress state; unloading the horizontal maximum principal stress or the horizontal minimum principal stress from the true triaxial sample according to the stress path change after excavation of the stope; continuing to load the vertical principal stress to the true triaxial sample until the true triaxial sample is destroyed to measure a compressive strength σ ch of the true triaxial sample under unloading of the horizontal maximum principal stress, and to measure a compressive strength σ cH of the true triaxial sample under unloading of the horizontal minimum principal stress.

[0012] In some embodiments, the step of determining the influence factor of stress and bedding on the length of the stope and the influence factor of stress and bedding on the width of the stope comprises: calculating the influence factor of stress and bedding on the width of the stope and the influence factor of stress and bedding on the length of the stope according to the compressive strength σ ch and the compressive strength σ cH .

[0013] In some embodiments, the calculation formula of the influence factor α of stress and bedding on the width of the stope according to the compressive strength σ ch and the compressive strength σ cH is:

[0014]

[0015] According to the compressive strength σ ch and the compressive strength σ cH The calculation formula of the influence factor β of the stope length is:

[0016]

[0017] Wherein, σ cH >σ ch The influence factor α of the stope width is less than 1, and the influence factor β of the stope length is greater than 1.

[0018] In some embodiments, the calculation formula of the length of the stope according to the influence factor of the stope length is:

[0019] L'=L×β;

[0020] The calculation formula of the width of the stope according to the influence factor of the stope width is:

[0021] W'=W×α;

[0022] Wherein, L' is the length of the stope after correction, W' is the width of the stope after correction, L is the length of the stope before correction, and W is the width of the stope before correction.

[0023] In some embodiments, the step of determining the in-situ stress state of the ore body comprises: measuring the in-situ stress state of the ore body by using the hydraulic fracturing method.

[0024] In some embodiments, the bedding state of the ore body further comprises the bedding tendency of the ore body, the bedding dip angle of the ore body, and the bedding thickness of the ore body.

[0025] In some embodiments, the step of arranging the stope along the direction perpendicular to the bedding direction of the ore body comprises: arranging the stope along the direction perpendicular to the bedding direction of the ore body by using the sublevel open stope and subsequent filling mining method; wherein the horizontal section of the stope is rectangular, and the long side of the horizontal section of the stope is perpendicular to the bedding direction of the ore body.

[0026] In some embodiments, in the step of determining the spatial relationship between the in-situ stress state and the bedding state and constructing a three-dimensional ore body model, the bedding direction of the ore body is perpendicular or close to perpendicular to the direction of the horizontal maximum principal stress, and the bedding direction of the ore body is parallel or close to parallel to the direction of the horizontal minimum principal stress.

[0027] The present application has the following technical effects relative to the prior art:

[0028] The present application adjusts the structure of the stope, and arranges the stope along the direction perpendicular to the bedding of the ore body. The arrangement considers the anisotropic characteristics of the mechanical properties of the layered rock mass under high stress conditions. The rock mass stability is better along the direction perpendicular to the bedding, i.e. parallel to the direction of the maximum horizontal principal stress. The rock mass stability is poorer along the direction parallel to the bedding, i.e. perpendicular to the direction of the maximum horizontal principal stress. Arranging the stope along the direction perpendicular to the bedding of the ore body can fully exert the stability of the rock mass to maintain the stability of the stope, improve the safety of the stope recovery, and reduce the support cost of the stope. Moreover, the present application determines the influence factors of stress and bedding on the length and width of the stope according to the arranged stope, and corrects the length and width of the stope according to the influence factors. Since the influence of the combined action of the ground stress and the bedding on the stability of the rock mass is considered, the anisotropic characteristics of the stability of the high-stress layered rock mass can be fully exerted, which helps to improve the self-stability of the stope. The design method helps to maximize the self-stability of the deep buried BIF type iron ore, and improves the safety and efficiency of the stope recovery. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0030] Figure 1 The main step flow chart of the stope structure parameter design method for the deep buried BIF type iron ore layered ore body in some embodiments of the present application;

[0031] Figure 2 The top view of the ground stress state and the bedding state of the ore body in some embodiments of the present application;

[0032] Figure 3 The front view of the ground stress state and the bedding state of the ore body in some embodiments of the present application;

[0033] Figure 4 The side view of the ground stress state and the bedding state of the ore body in some embodiments of the present application;

[0034] Figure 5 The top view of the stope stress state and the bedding state in some embodiments of the present application;

[0035] Figure 6 The front view of the stope stress state and the bedding state in some embodiments of the present application;

[0036] Figure 7 The side view of the stope stress state and the bedding state in some embodiments of the present application.

[0037] Figure: 1 - stope; 2 - bedding. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work belong to the scope of protection of the present application.

[0039] The purpose of the present application is to provide a deep BIF type iron ore bedded orebody stope structure parameter design method to solve the problems in the prior art, considering the combined effect of ground stress and bedding on the stability of rock mass, which can effectively improve the stability of the stope and ensure the safety and efficiency of the recovery process.

[0040] In order to make the above-mentioned purposes, characteristics and advantages of the present application more apparent, easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0041] The present application provides a deep BIF type iron ore bedded orebody stope structure parameter design method, as shown in Figures 1 to 7 , wherein Figure 1 is the main step flow chart of the method, including:

[0042] Step S1: determining the ground stress state of the orebody;

[0043] Step S2: determining the bedding state of the orebody;

[0044] Step S3: determining the spatial relationship between the ground stress state and the bedding state and constructing a three-dimensional orebody model;

[0045] Step S4: based on the three-dimensional orebody model, arranging the stope 1 along the bedding direction perpendicular to the orebody;

[0046] Step S5: determining the influence factor of stress and bedding 2 on the length of the stope and the influence factor on the width of the stope;

[0047] Step S6: correcting the length of the stope 1 according to the influence factor of the length of the stope, and correcting the width of the stope 1 according to the influence factor of the width of the stope.

[0048] Based on the above steps S1-S6, it should be noted that in step S1, the ground stress state of the orebody is measured, the size and direction of the ground stress are analyzed, the direction and size of the horizontal maximum principal stress σ H and the horizontal minimum principal stress σ h , and the vertical principal stress σ VThe direction and size of the stress.

[0049] In step S2, the ore body bedding state of the BIF type iron mine is investigated in the field, and the bedding property of the ore body is determined, which at least includes the bedding direction.

[0050] In step S3, the spatial relationship between the ground stress and the bedding 2 is determined based on the ground stress state and the bedding condition determined in step S1 and step S2, and a three-dimensional ore body model containing the ground stress state and the bedding state is constructed, wherein the bedding direction, i.e. the direction of the bedding and the horizontal maximum principal stress σ H near vertical, the bedding direction is nearly parallel to the horizontal minimum principal stress σ h parallel, which is consistent with the metallogenic theory of the BIF type iron mine.

[0051] In step S4, based on the three-dimensional ore body model of the ground stress and the bedding of the ore body in step S3, the stope 1 is arranged vertically to the bedding direction, i.e. parallel to the direction of the horizontal maximum principal stress, Figure 2 In step S4, based on the three-dimensional ore body model of the ground stress and the bedding of the ore body in step S3, the stope 1 is arranged vertically to the bedding direction, i.e. parallel to the direction of the horizontal maximum principal stress,

[0052] In step S5, considering the influence of the high stress and the bedding 2 of the deep buried BIF type iron mine on the mechanical properties and stability of the rock mass, the stress and the bedding 2 are introduced to affect the stope width and the stope length.

[0053] In step S6, the stope length and the stope width are corrected to obtain the corrected stope parameters, wherein the length direction of the stope 1 is parallel to the direction of the horizontal maximum principal stress, the width direction of the stope 1 is parallel to the direction of the horizontal minimum principal stress, and the height direction of the stope 1 is parallel to the direction of the vertical principal stress.

[0054] It should be noted that the present application only designs the length and width of the stope 1, and the height of the stope 1 is determined according to factors such as equipment capacity.

[0055] The structure and parameter design of the stope 1 of the present application consider the influence of the combined action of the ground stress and the bedding 2 on the stability of the rock mass, fully play the anisotropy characteristics of the stability of the high stress layered rock mass, and help to improve the stability of the stope itself. The design method helps the deep buried BIF type iron mine to maximize its own stability, and improves the safety and efficiency of the stope recovery.

[0056] And it should be noted that the present application does not limit the order of step S1 and step S2, i.e. step S1 can be executed first and step S2 can be executed later, or step S2 can be executed first and step S1 can be executed later, or step S1 and step S2 can be executed simultaneously.

[0057] In some embodiments, the above step S2 comprises:

[0058] A true triaxial loading and unloading test was conducted based on the ground stress state, the bedding state of stope 1, and the stress path changes after the excavation of stope 1.

[0059] Determine the influence factors of stress and bedding on stope length and stope width.

[0060] In some embodiments, the step of "conducting a true triaxial loading and unloading test based on the ground stress state, the bedding state of stope 1, and the stress path changes after the excavation of stope 1" includes:

[0061] True triaxial samples were taken from the ore body and processed into true triaxial samples with the same bedding state as stope 1.

[0062] The true triaxial specimens were loaded to the original rock stress state according to the in-situ stress state.

[0063] Based on the stress path changes after the excavation of mining area 1, the maximum or minimum principal stress of the horizontal unloading horizontal test specimen is determined.

[0064] The vertical principal stress was continued to be applied to the true triaxial specimen until the specimen failed. The compressive strength σ of the true triaxial specimen under the maximum horizontal principal stress was measured. ch The compressive strength σ of the true triaxial specimen under the minimum principal stress at the unloading level was measured. cH .

[0065] The steps for "determining the influence factors of stress and bedding on stope length and stope width" include:

[0066] According to the compressive strength σ ch and compressive strength σ cH The influence factors of the stope width and the stope length were calculated.

[0067] In some embodiments, based on the compressive strength σ ch and compressive strength σ cH The formula for calculating the influence factor α of the stope width is as follows:

[0068]

[0069] According to the compressive strength σ ch and compressive strength σ cH The formula for calculating the influence factor β of the stope length is as follows:

[0070]

[0071] Among them, tensile strength σ cH Tensile strength σ chThe influence factor α of the stope width is less than 1, while the influence factor β of the stope length is greater than 1.

[0072] In some implementations, the formula for calculating the length of stope 1, based on the influence factor of stope length, is as follows:

[0073] L' = L × β;

[0074] The formula for calculating the width of stope 1, adjusted according to the influence factor of stope width, is as follows:

[0075] W' = W × α;

[0076] Where L' is the length of the corrected stope 1, W' is the width of the corrected stope 1, L is the length of the stope 1 before correction, and W is the width of the stope 1 before correction.

[0077] After introducing the combined influence factor of stress and bedding 2, the width of the stope is appropriately reduced because the rock mass strength is lower in the direction parallel to the bedding; and the length of the stope is appropriately increased because the rock mass strength is higher in the direction perpendicular to the bedding.

[0078] In some embodiments, step S above, the step of "arranging the stope along the bedding direction perpendicular to the ore body" includes:

[0079] The staged open-stope and subsequent backfilling mining method was adopted, and the stope 1 was arranged along the bedding direction perpendicular to the ore body.

[0080] Among them, such as Figure 2 As shown, the horizontal section of stope 1 is rectangular, and the long side of the horizontal section of stope 1 is perpendicular to the bedding direction of the ore body. This horizontal section is the horizontal plane where the maximum and minimum horizontal principal stresses are located.

[0081] It should be noted that this invention adopts the staged open-cut followed by backfilling mining method, and stope 1 is a rectangular stope. The original stope structure design did not consider the influence of in-situ stress on the mechanical properties of layered rock mass. Its stope long axis is arranged parallel to the bedding direction and perpendicular to the direction of maximum principal stress. After the excavation of stope 1, it is very easy to become unstable and fail under the action of in-situ stress and bedding 2.

[0082] This embodiment adjusts the stope structure so that the long axis of the stope is parallel to the direction of the maximum horizontal principal stress and perpendicular to the bedding direction. This arrangement takes into account the anisotropic mechanical properties of layered rock masses under high stress conditions. When the arrangement is perpendicular to the bedding direction (i.e., parallel to the direction of the maximum horizontal principal stress), the rock mass stability is better; conversely, when the arrangement is parallel to the bedding direction (i.e., perpendicular to the direction of the maximum horizontal principal stress), the rock mass stability is poorer. Therefore, adopting a stope structure with the long axis parallel to the maximum horizontal principal stress and perpendicular to the bedding direction can fully utilize the inherent stability of the rock mass to maintain the stability of stope 1, improve the safety of stope mining, and reduce the support cost of stope 1.

[0083] In some embodiments, the step S1 comprises:

[0084] The in-situ stress state of the ore body is measured by using hydraulic fracturing method.

[0085] It should be noted that the in-situ stress state of the ore body can also be measured by using other methods, such as stress relief method, which is not limited in the present application.

[0086] In some embodiments, the bedding state of the ore body further comprises a bedding tendency of the ore body, a bedding dip angle of the ore body and a bedding thickness of the ore body.

[0087] In some embodiments, the step of "loading the true triaxial sample to the in-situ stress state according to the in-situ stress state" comprises:

[0088] loading the true triaxial sample to the in-situ stress level at a first rate according to the magnitude and direction of the horizontal maximum principal stress, the magnitude and direction of the horizontal minimum principal stress and the magnitude and direction of the vertical principal stress;

[0089] The step of "unloading the horizontal maximum principal stress or the horizontal minimum principal stress of the true triaxial sample" comprises:

[0090] unloading the horizontal maximum principal stress or the horizontal minimum principal stress of the true triaxial sample at a second rate;

[0091] The step of "continuing to load the vertical principal stress of the true triaxial sample until the true triaxial sample is destroyed" comprises:

[0092] continuing to load the vertical principal stress of the true triaxial sample at a third rate until the true triaxial sample is destroyed;

[0093] wherein the first rate is 0.5 Mpa / s, the second rate is 0.1 Mpa / s and the third rate is 0.1 Mpa / s.

[0094] It should be noted that the values of the first rate, the second rate and the third rate can be set according to actual conditions, which is not limited in the present application.

[0095] In some embodiments, in the step of "determining the spatial relationship between the in-situ stress state and the bedding state and constructing a three-dimensional ore body model", the spatial relationship between the in-situ stress state and the bedding state is determined by:

[0096] the bedding direction of the ore body is perpendicular or nearly perpendicular to the direction of the horizontal maximum principal stress, and the bedding direction of the ore body is parallel or nearly parallel to the direction of the horizontal minimum principal stress.

[0097] In a specific embodiment, the horizontal maximum principal stress σ His 47.4 MPa, and the direction is near NE, i.e., northeast direction; the horizontal maximum principal stress σ h is 31.9 MPa, and the vertical principal stress σ V is 32.7 MPa.

[0098] The ore body bedding 2 is output in a near-vertical manner, and the direction is NW, i.e., northwest direction.

[0099] According to the bedding characteristics of the stope 1 and the stress path change characteristics of the stope 1 excavation, the ore body is sampled to process the true triaxial sample in the same way as the stope bedding. According to the measured stress field σ H , σ h , σ V of the ore body, the three principal stresses are restored to the original rock stress level by using a loading rate of 0.5 MPa / s; then according to the stress path change after the stope 1 excavation, σ H or σ h is unloaded at a rate of 0.1 MPa / s; finally, σ V is loaded at a rate of 0.1 MPa / s until the sample is damaged, and σ H or σ h remains unchanged, and the high compressive strength σ CH and σ Ch under the action of only the horizontal maximum principal stress or only the horizontal minimum principal stress are measured, respectively. In this embodiment, σ CH and σ Ch are 128.5 MPa and 66.2 MPa, respectively.

[0100] Stope parameter design: the high stress layered rock mass mechanical parameters σ CH and σ Ch measured by the true triaxial experiment are brought into the stress and bedding influence factor calculation formula, and the influence factor α of the stope width is calculated to be 0.88, and the influence factor β of the stope length is calculated to be 1.10.

[0101] In this embodiment, the original stope parameters are a width of 20 m and a length of 70 m, and after introducing the stress and bedding influence factors on the stope parameters, the stope length of this embodiment is adjusted to 80 m, and the width is 18 m. After introducing the stress and bedding combined influence factors, the stope width is appropriately reduced because the rock mass strength in the parallel bedding direction is low, and the stope length is appropriately increased because the rock mass strength in the vertical bedding direction is high.

[0102] The deep buried BIF type iron ore layered ore body stope structure parameter design method has the following technical effects:

[0103] (1) The structural design of the stope takes into account the combined effect of ground stress and bedding 2 on the stability of the rock mass. Through the structural design of the long strip stope with the long axis perpendicular to the bedding direction and parallel to the direction of the maximum horizontal principal stress, the stability of stope 1 can be maximized.

[0104] (2) The parameter design of mining area 1 takes into account the influence of the combined effect of geostress and bedding on the mechanical properties of rock mass. The rock mass strength after stress path change is tested by true triaxial test. Then, the length and width of mining area are optimized based on the difference in mechanical properties of high-stress layered rock mass, which can give full play to the anisotropic characteristics of mechanical properties of high-stress layered rock mass.

[0105] (3) By designing the mining structure, that is, the long axis of the mining area is parallel to the direction of the maximum horizontal principal stress, and the long axis of the filling body, the rock drilling roadway and the ore extraction roadway in the mining area are all parallel to the direction of the maximum horizontal principal stress, the stability of the filling body and the roadway can be guaranteed to the greatest extent.

[0106] (4) By designing the mining area structure and parameters, the cost of mining area support can be reduced while ensuring safe mining.

[0107] (5) By designing the long axis of the mining area to be parallel to the direction of the maximum horizontal principal stress, the blasting ore falling direction is also parallel to the direction of the maximum horizontal principal stress. The blasting ground stress clamping effect is minimized in this direction, which is conducive to reducing the consumption of explosives and blasting vibration, and improving the blasting effect.

[0108] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for designing the structural parameters of a stope in a deep-buried BIF-type layered iron ore body, characterized in that, Includes the following steps: Determine the geostress state of the ore body; Determine the bedding state of the ore body; Determine the spatial relationship between the geostress state and the bedding state, and construct a three-dimensional orebody model; Based on the three-dimensional ore body model, the mining area is arranged along the bedding direction perpendicular to the ore body; Determine the influence factors of stress and bedding on stope length and stope width; The length of the stope is corrected according to the influence factor of the stope length, and the width of the stope is corrected according to the influence factor of the stope width; The stress state of the ore body includes the magnitude and direction of the maximum horizontal principal stress, the magnitude and direction of the minimum horizontal principal stress, and the magnitude and direction of the vertical principal stress. The bedding state of the ore body includes the bedding direction of the ore body.

2. The method for designing the structural parameters of a deep-buried BIF-type layered iron ore body stope according to claim 1, characterized in that, The steps for "determining the influence factors of stress and bedding on stope length and stope width" include: A true triaxial loading and unloading test was conducted based on the ground stress state, the bedding state of the mining area, and the stress path changes after the mining area was excavated. Determine the influence factors of stress and bedding on the stope length and the stope width.

3. The method for designing the structural parameters of a deep-buried BIF-type layered iron ore body stope according to claim 2, characterized in that, The steps of "conducting a true triaxial loading and unloading test based on the bedding state of the stope and the changes in the excavation stress path of the stope" include: True triaxial samples were taken from the ore body and processed into true triaxial samples with the same bedding state as the stope. The true triaxial specimen was loaded to the original rock stress state according to the described geostress state. Based on the stress path changes after the mining area is excavated, the maximum or minimum horizontal principal stress is unloaded from the true triaxial specimen. The vertical principal stress is continued to be applied to the true triaxial specimen until the specimen fails. The compressive strength σ of the true triaxial specimen is then measured after unloading the maximum horizontal principal stress. ch And the compressive strength σ of the true triaxial specimen was measured under the condition of unloading the minimum principal stress at the horizontal level. cH .

4. The method for designing the structural parameters of a deep-buried BIF-type layered iron ore body stope according to claim 3, characterized in that, The steps of "determining the influence factors of stress and bedding on the stope length and on the stope width" include: According to the compressive strength σ ch and the compressive strength σ cH The influence factors of the stope width and the stope length are calculated.

5. The method for designing the structural parameters of a deep-buried BIF-type layered iron ore body stope according to claim 4, characterized in that, According to the compressive strength σ ch and the compressive strength σ cH The formula for calculating the influence factor α of the stope width is as follows: According to the compressive strength σ ch and the compressive strength σ cH The formula for calculating the influence factor β of the stope length is as follows: Where, σ cH >σ ch The influence factor α of the stope width is less than 1, and the influence factor β of the stope length is greater than 1.

6. The method for designing the structural parameters of a deep-buried BIF-type layered iron ore body stope according to claim 5, characterized in that, The formula for calculating the length of a stope, adjusted according to the influence factor of the stope length, is as follows: L' = L × β; The formula for calculating the width of the stope, adjusted according to the influence factor of the stope width, is as follows: W' = W × α; Where L' is the corrected length of the mining area, W' is the corrected width of the mining area, L is the original length of the mining area, and W is the original width of the mining area.

7. The method for designing the structural parameters of a deep-buried BIF-type layered iron ore body stope according to claim 1, characterized in that, The steps for "determining the geostress state of an ore body" include: The geostress state of the ore body was measured using the hydraulic fracturing method.

8. The method for designing the structural parameters of a deep-buried BIF-type layered iron ore body stope according to claim 1, characterized in that, The bedding state of the ore body also includes the bedding dip, the bedding angle, and the bedding thickness of the ore body.

9. The method for designing the structural parameters of a deep-buried BIF-type layered iron ore body stope according to claim 1, characterized in that, The steps of "arranging the stope along the bedding direction perpendicular to the ore body" include: The stope is arranged along the bedding direction perpendicular to the ore body using the staged open-stope and subsequent backfilling mining method. The horizontal cross-section of the mining area is rectangular, and the long side of the horizontal cross-section of the mining area is perpendicular to the bedding direction of the ore body.

10. The method for designing the structural parameters of a deep-buried BIF-type layered iron ore body stope according to claim 1, characterized in that, In the step of "determining the spatial relationship between the geostress state and the bedding state and constructing a three-dimensional ore body model": The bedding direction of the ore body is perpendicular or nearly perpendicular to the direction of the horizontal maximum principal stress, and the bedding direction of the ore body is parallel or nearly parallel to the direction of the horizontal minimum principal stress.

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