A closed-loop feedback type design method for treating length of soft foundation of dump

Abstract

This invention belongs to the field of open-pit mining technology, specifically relating to a closed-loop feedback design method for the segmented treatment length of soft foundations in spoil heaps. By selecting engineering geological profiles of open-pit mine spoil heaps year by year, the physical and mechanical parameters of the soil and rock mass are obtained to determine the slope safety reserve coefficient. The Morgenstern-Price method is used to calculate the slope stability coefficient step by step. The difference between the stability coefficient and the safety reserve coefficient is compared, and soft foundations that do not meet safety requirements are treated in segments. The closed-loop feedback process is used for verification until all steps meet the standards, iterating year by year to complete the full-cycle treatment. This invention eliminates the need for widening, large-scale backfilling, and additional reinforcement, and can accurately determine the segmented treatment length of soft foundations. It has the advantages of low cost, simple construction, and precise slope stability control, and is suitable for the treatment of soft foundation slopes in open-pit mine spoil heaps.

Description

Technical Field

[0001] This invention belongs to the field of open-pit mining technology, specifically relating to a closed-loop feedback design method for the segmented treatment length of soft foundation in spoil heaps. Background Technology

[0002] In open-pit mining, spoil heaps serve as crucial sites for disposing of overburden, and their slope stability directly impacts mine safety and economic efficiency. When internal spoil heaps are situated on weak foundations with low foundation strength, they are prone to slippage, especially when the slip surface develops along weak layers such as the top and bottom of the coal seam, significantly increasing the risk of slope instability. A landslide can not only damage equipment and disrupt transportation systems but also potentially cause casualties, severely threatening safe mine operations. Therefore, slope management of spoil heaps is of significant practical importance. Patent CN118997192A discloses a method for reinforcing reserved slopes of open-pit mine spoil heaps with pre-embedded anchors. This method uses pre-embedded anchors to reinforce the slopes of the spoil heaps. Patent CN119221498B discloses a gabion reinforcement system to prevent damage to backfill spoil heaps in open-pit mines. This method improves slope stability by laying gabions on the base surface. Patent CN112836283B discloses a method for determining the extent of soft base damage and backfill block range in spoil heaps. This method controls slope stability by damaging the base of the spoil heap and backfilling large blocks. Patent CN113128020B discloses a method for widening and treating potential slip slopes in open-pit mines. This method improves slope stability by evaluating slope zones and widening different slope zones.

[0003] These patents all address the reinforcement or treatment of open-pit mine slopes from various angles, including anchoring, gabion mesh, foundation damage and backfilling with large blocks, and widening the slope. However, none of them consider how to improve slope stability when widening the slope of a spoil heap is not feasible or when large blocks of material are lacking. Furthermore, the use of anchoring and gabion mesh methods for slope treatment has drawbacks such as high cost and long construction periods. Therefore, there is an urgent need for a spoil heap treatment method that requires neither widening nor large backfilling materials, is low-cost, and easy to construct. Summary of the Invention

[0004] To address the technical problems existing in the treatment of existing spoil heap slopes, this invention provides a closed-loop feedback design method for the segmented treatment length of soft foundation in spoil heaps. This method does not require large backfill materials, widening of the slope, or various slope reinforcement methods. It can improve slope stability simply by treating the soft foundation of the spoil heap in segments. Moreover, it can accurately design the length of each segmented treatment, and has the characteristics of low cost, simple process, and easy on-site implementation.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A closed-loop feedback design method for the segmented treatment length of soft foundation in spoil heaps includes the following steps: S1. Select and number the initial annual engineering geological profile of the open-pit mine spoil heap to be analyzed; S2. Obtain the physical and mechanical parameters of the soil and rock mass on the slope of the spoil heap; S3. Determine the safety reserve coefficient K of the spoil heap slope based on the slope service life and relevant design specifications. a ; S4. For the initial annual engineering geological profile of the spoil heap, calculate the slope stability coefficient Fs step by step from low to high according to the step level. i ; S5. Calculate the difference C between the slope stability coefficient and the safety reserve coefficient for each step. i =Fs i -K a If C i If the value is less than the predetermined threshold M, the soft substrate corresponding to this step needs to be treated in stages. If there are two or more steps that need to be treated in stages, the treatment should start from the lower level step, and the difference C between the stability coefficient and the safety reserve coefficient of each step should be recalculated after each treatment. i =Fs i -K a Until the slope stability coefficient of each step meets the reserve requirements, use CAD software to draw the plan of soft foundation treatment for that year. S6. Select and number the engineering geological profile of the spoil heap for the next year in the open-pit mine. S7. For the engineering geological profile of the spoil heap for the next year, calculate the slope stability coefficient Fs step by step from low to high according to the step level. i ; S8. Calculate the difference C between the slope stability coefficient and the safety reserve coefficient for each step. i =Fs i -K a If C i If the value is less than the predetermined threshold M, the soft substrate corresponding to this step needs to be treated in stages. If there are two or more steps that need to be treated in stages, the treatment should start from the lower level step, and the difference C between the stability coefficient and the safety reserve coefficient of each step should be recalculated after each treatment. i =Fs i -K a Until the slope stability coefficient of each step meets the reserve requirements, use CAD software to draw the plan of soft foundation treatment for that year. S9. Repeat steps S6 to S8 until the stability of the slopes of all annual spoil heaps in the open-pit mine meets the safety reserve requirements.

[0006] In steps S4 and S7, the Morgenstern-Price method is used to calculate the slope stability coefficient.

[0007] The Morgenstern-Price method for calculating slope stability coefficients is as follows: Step 1: Based on the engineering geological profile of the spoil heap, locate the soft foundation and weak coal seam, and determine the location and shape of the potential sliding surface of the slope; divide the sliding body into several vertical soil strips along the horizontal direction, numbered sequentially as i=1, 2, ..., n; input the cohesion c of the soil and rock mass corresponding to the bottom of the soil strip. i internal friction angle φ i , soil bar gravity W i α, the dip angle of the bottom surface of the soil strip i Length of the bottom surface of the soil strip l i ; Step 2: The forces borne by a single soil strip include: the weight of the soil strip itself, W. i Normal reaction force N at the bottom of the soil strip i Shear force T at the bottom of the soil strip i The inter-strip normal force E between the left side of the soil strip and the (i-1)th soil strip i-1 Inter-strip tangential force X i-1 The inter-strip normal force E between the right side of the soil strip and the (i+1)th soil strip i Inter-strip tangential force X i ; Vertical force balance: W i +X i-1 -X i =N i cosα i + T i sinα i Horizontal force balance: E i-1 -E i =N i sinα i -T i cosα i Moment balance: Taking moments about the midpoint of the bottom surface of the soil strip, the resultant moment is 0. The bottom shear force and stability coefficient satisfy: T i =(c i l i +N i tanφ i ) / Fs i Where: Fs i This refers to the slope stability coefficient. Step 3: Using the Morgenstern-Price general inter-strip force function f(x), establish the proportional relationship between the inter-strip tangential force and the normal force: Xi =λ·f(x)·E i Where: λ is the inter-strip force proportionality coefficient, which is solved iteratively through equilibrium conditions; Step 4: Set the initial stability coefficient Fs i Substitute the proportionality coefficient λ into the equilibrium equation, and recursively calculate the inter-strip forces and bottom reactions from the slope toe to the slope crest; verify whether the overall force equilibrium and moment equilibrium are satisfied; correct Fs using the Newton-Raphson iteration method. i Repeat the calculation with λ until convergence, i.e., the error ≤ the preset value; the converged Fs i This is the slope stability coefficient of the profile; Step 5: Following the order of the steps from low to high, and using the top surface of each step as the calculation boundary, repeat the above steps to obtain the slope stability coefficient Fs for each horizontal step. i .

[0008] The physical and mechanical parameters mentioned in step S2 include the rock mass unit weight γ and cohesion c. i internal friction angle φ i .

[0009] The relevant design specification mentioned in step S3 is GB50197-2015 "Design Specification for Open-pit Coal Mines", and the determined safety reserve factor K a =1.2.

[0010] The segmented treatment of the soft substrate described in steps S5 and S8 is carried out in the region where the slip surface develops along the weak layer of the coal seam top and bottom plate, and the weak layer is the weak layer of the bottom plate of coal seam 2-1.

[0011] The starting position for the segmented treatment in steps S5 and S8 is the position where the depth can be reduced to the bottom of the coal seam.

[0012] In steps S5 and S8, the segmented treatment is a step-by-step progressive treatment, meaning the steps progress from low to high. After each segment is completed, the slope stability of each step is recalculated until the C value of all steps is reached. i ≥M.

[0013] The predetermined threshold M mentioned in steps S5 and S8 is -0.005.

[0014] Compared with the prior art, the beneficial effects of this invention are: (1) The present invention constructs a closed-loop feedback design mechanism for the segmented treatment length of soft foundation in spoil heaps, which can realize the dynamic verification and optimization of annual-slope-treatment parameters.

[0015] (2) This invention does not require slow-down work, does not increase the land occupied by external discharge, effectively reduces the disturbance to the surrounding ecological environment, and reduces the risk of coal spontaneous combustion and dust.

[0016] (3) The present invention calculates the stability coefficient step by step based on the Morgenstern-Price method, which can accurately determine the treatment length of each segment of the soft substrate and improve the design targeting and reliability.

[0017] (4) Based on determining the treatment length of each segment of the soft substrate, the present invention uses CAD software to draw a plan of the soft substrate treatment in the open-pit mine spoil heap, which conforms to the characteristics of industrial Internet technology in the key digital technology patent classification system and significantly improves the informatization level of open-pit mine production management.

[0018] (5) The present invention adopts an iterative process of “treatment-feedback-recalculation”, which has obvious digital, model-based and intelligent decision-making characteristics, and is easy to integrate and apply in engineering software.

[0019] (6) The present invention has a standardized process, clear parameters, and is easy to implement. It can form a digital design method for open-pit mine slope management and has good promotion and application value. Attached Figure Description

[0020] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0021] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0022] Figure 1 This is a flowchart of a closed-loop feedback precise design method for the segmented treatment length of soft foundation in a spoil heap, as described in an embodiment of the present invention. Figure 2 This is a schematic diagram showing the location of the selected geological profile of the internal spoil heap in 2027 in an embodiment of the present invention; Figure 3 This is an engineering geological profile of the 27-NP1 internal spoil heap in 2027, as described in this embodiment of the invention. Figure 4 This is a diagram showing the evaluation results of the step-by-step slope stability of section 27-NP1 in this embodiment of the invention; Figure 5This is a diagram showing the slope stability evaluation results of each horizontal step after treating the soft foundation at the 27-NP1 section + 872m horizontal step in this embodiment of the invention. Figure 6 This is a diagram showing the slope stability evaluation results of each horizontal step after treating the soft foundation at the 27-NP1 section + 896m horizontal step in this embodiment of the invention. Figure 7 This is a plan view of the soft foundation treatment of the open-pit mine spoil heap in 2027, as described in this embodiment of the invention. Figure 8 This is a plan view showing the location of the selected engineering geological profile of the internal spoil heap in 2028, as described in this embodiment of the invention. Figure 9 This is the engineering geological profile of the 28-NP1 internal spoil heap in 2028, as described in this embodiment of the invention. Figure 10 This is a diagram showing the stability evaluation results of the step-by-step slope of section 28-NP1 in this embodiment of the invention. Figure 11 This is a diagram showing the slope stability evaluation results of each horizontal step after treating the soft foundation at the 28-NP1 section + 824m horizontal step in this embodiment of the invention. Figure 12 This is a plan view of the soft foundation treatment of the open-pit mine spoil heap in 2028, as described in this embodiment of the invention. Figure 13 This is a plan view showing the location of the selected engineering geological profile of the internal spoil heap in 2029, as described in this embodiment of the invention. Figure 14 This is the engineering geological profile of the 29-NP1 internal spoil heap in 2029, as described in this embodiment of the invention. Figure 15 This is a diagram showing the evaluation results of the step-by-step slope stability of section 29-NP1 in this embodiment of the invention; Figure 16 This is a diagram showing the slope stability evaluation results of each horizontal step after treating the soft foundation at the 29-NP1 section + 800m horizontal step in this embodiment of the invention. Figure 17 This is a diagram showing the slope stability evaluation results of each horizontal step after treating the soft foundation at the 29-NP1 section +824m horizontal step in this embodiment of the invention. Figure 18 This is a plan view of the soft foundation treatment of the open-pit mine spoil heap in 2029, as described in this embodiment of the invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. These descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the claims of the present invention. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention. Example 1:

[0025] This embodiment proposes a closed-loop feedback design method for the segmented treatment length of soft foundation in spoil heaps, such as... Figure 1 As shown, it includes: Step S1: Select and number the initial annual engineering geological profile of the open-pit mine spoil heap to be analyzed; In this embodiment, the selected location of the 2027 internal spoil heap engineering geological profile of the open-pit mine is as follows: Figure 2 As shown, the engineering geological profile of the internal spoil heap is numbered 27-NP1. The engineering geological profile of the internal spoil heap is as follows: Figure 3 As shown.

[0026] Step S2: Obtain the physical and mechanical parameters of the soil and rock mass on the slope of the spoil heap; In this embodiment, based on previous geological exploration and physical and mechanical tests of soil and rock, the physical and mechanical parameters of the slope soil and rock are obtained as shown in Table 1.

[0027] Table 1 Physical and mechanical parameters of soil and rock Step S3: Determine the safety reserve coefficient K of the spoil heap slope based on the slope service life and relevant design specifications. a ; In this embodiment, the safety reserve coefficient K of the internal spoil heap slope is determined based on the slope service life and the "Code for Design of Open-pit Coal Mines" (GB50197-2015). a It is 1.2.

[0028] Step S4: For the initial annual engineering geological profile of the spoil heap, calculate the slope stability coefficient Fs step by step from low to high according to the step level. i ; In this embodiment, based on the Morgenstern-Price method, the slope stability coefficient Fs of the 2027 internal spoil heap engineering geological profile is calculated step by step from low to high according to the step level.i The calculation results are shown in Table 2. Figure 4 As shown; Table 2. Calculation Results of Slope Stability of Internal Waste Dump in 2027 Step S5: Calculate the difference C between the slope stability coefficient and the safety reserve coefficient for each step. i =Fs i -K a If C i If the value is less than the predetermined threshold M, the soft substrate corresponding to this step needs to be treated in stages. If there are two or more steps that need to be treated in stages, the treatment should start from the lower level step, and the difference C between the stability coefficient and the safety reserve coefficient of each step should be recalculated after each treatment. i =Fs i -K a Until the slope stability coefficient of each step meets the reserve requirements, use CAD software to draw the plan of soft foundation treatment for that year. In this embodiment, the predetermined threshold M is -0.005. Based on Table 2, the difference C between the stability coefficient and the safety reserve coefficient of each level step slope of the spoil heap in 2027 is calculated. i The results are shown in Table 3. Table 3. Calculation Results of the Difference Between the Stability Coefficient and the Safety Reserve Coefficient of Each Level Step Slope in the Internal Waste Disposal Site in 2027 Table 3 shows the difference C between the horizontal steps at +872m, +896m, and +908m. i The slope was less than the predetermined threshold M, therefore soft foundation treatment was required. The sliding surfaces of the +872m, +896m, and +908m horizontal steps slid along the weak layer of the 2-1 coal seam floor. Due to mining design limitations, it was not possible to directly descend to the 2-1 coal seam floor. Therefore, the soft foundation was treated in stages starting from the location where it could be descended to the 2-1 coal seam floor. The slope stability results of each horizontal step after the soft foundation treatment at the +872m horizontal step are shown in Table 4. Figure 5 As shown, the length of the weak layer in the soft foundation treated at this level is 21m. The difference C between the stability coefficient and the safety reserve coefficient of the slope at each level step after the soft foundation treatment at the +872m level step is also shown. i The results are shown in Table 5.

[0029] As shown in Table 5, after the soft foundation treatment of the +872m horizontal step was completed, the difference C between the slope stability coefficient and the safety reserve coefficient of the +896m horizontal step was less than the predetermined threshold M. Therefore, soft foundation treatment is still required for the +896m horizontal step. The slope stability results of each horizontal step after soft foundation treatment are shown in Table 6. Figure 6As shown, based on the treatment of the soft foundation at the +872m horizontal step, an additional 6m of weak soft foundation layer was treated, bringing the total treated weak soft foundation layer to 27m. According to Table 6, the difference C between the slope stability coefficient and the safety reserve coefficient of each horizontal step after the treatment of the soft foundation at the +896m horizontal step of the spoil heap in 2027 was calculated. i The results are shown in Table 7. Given that the difference C between the slope stability coefficient and the safety reserve coefficient of the +908m horizontal step is greater than the predetermined threshold M after the soft foundation treatment of the +896m horizontal step, the soft foundation treatment of this horizontal step will no longer be carried out.

[0030] Table 4. Calculation Results of Slope Stability After Soft Foundation Treatment at the Internal Waste Disposal Site +872m Horizontal Step in 2027 Table 5. Calculation Results of the Difference Between Slope Stability Coefficient and Safety Reserve Coefficient of Each Level Bench After Soft Foundation Treatment at the +872m Level Bench of the Internal Waste Disposal Site in 2027 Table 6. Calculation Results of Slope Stability After Soft Foundation Treatment at the Internal Waste Disposal Site + 896m Horizontal Step in 2027 Table 7. Calculation Results of the Difference Between Slope Stability Coefficient and Safety Reserve Coefficient of Each Horizontal Step After Soft Foundation Treatment at the +896m Horizontal Step of the Internal Waste Disposal Site in 2027 After completing the segmented and precise treatment of the soft foundation of the internal spoil heap in 2027, a plan view of the soft foundation treatment of the open-pit mine's internal spoil heap in 2027 was drawn using CAD software, based on the location of the soft foundation treatment. Figure 7 As shown.

[0031] Step S6: Select and number the engineering geological profile of the open-pit mine's spoil heap for the next year; In this embodiment, the selected location of the 2028 internal spoil heap engineering geological profile is as follows: Figure 8 As shown, the engineering geological profile of the internal spoil heap is numbered 28-NP1. The engineering geological profile of the internal spoil heap is as follows: Figure 9 As shown.

[0032] Step S7: For the engineering geological profile of the spoil heap for the next year, calculate the slope stability coefficient Fs step by step from low to high according to the step level. i ; In this embodiment, based on the Morgenstern-Price method, the slope stability coefficient Fs of the 2028 internal spoil heap engineering geological profile is calculated step by step from low to high according to the step level. i The calculation results are shown in Table 8. Figure 10 As shown; Table 8. Calculation Results of Slope Stability of Internal Waste Dump in 2028 Step S8: Calculate the difference C between the slope stability coefficient and the safety reserve coefficient for each step. i =Fs i -K a If C i If the value is less than the predetermined threshold M, the soft substrate corresponding to this step needs to be treated in stages. If there are two or more steps that need to be treated in stages, the treatment should start from the lower level step, and the difference C between the stability coefficient and the safety reserve coefficient of each step should be recalculated after each treatment. i =Fs i -K a Until the slope stability coefficient of each step meets the reserve requirements, use CAD software to draw the plan of soft foundation treatment for that year. In this embodiment, the predetermined threshold M is -0.005. Based on Table 2, the difference C between the stability coefficient and the safety reserve coefficient of each level step slope of the spoil heap in 2028 is calculated. i The results are shown in Table 9; Table 9. Calculation Results of the Difference Between Stability Coefficient and Safety Reserve Coefficient of Each Level Step Slope in the Internal Waste Disposal Site in 2028 Table 9 shows the difference C between the horizontal steps at +824m and +848m. i The slope is less than the predetermined threshold M, therefore soft foundation treatment is required. In this embodiment, the sliding surfaces of the +824m and +848m horizontal steps of the 2028 internal spoil heap slid along the weak layer of the 2-1 coal seam floor. Therefore, the soft foundation was treated in segments starting from the +824m horizontal step. The results of the soft foundation treatment at the +824m horizontal step are shown in Table 10. Figure 11 Based on Table 10, calculate the difference C between the slope stability coefficient and the safety reserve coefficient of each horizontal step after the soft foundation treatment of the +824m horizontal step of the internal spoil heap in 2028. i The results are shown in Table 11. Given that the difference C between the slope stability coefficient and the safety reserve coefficient of the +848m horizontal step is greater than the predetermined threshold M after the soft foundation treatment of the +824m horizontal step, the soft foundation treatment of this horizontal step will no longer be carried out.

[0033] Table 10. Calculation Results of Slope Stability After Soft Foundation Treatment at the Internal Waste Disposal Site +824m Horizontal Step in 2028 Table 11 Calculation Results of the Difference Between Slope Stability Coefficient and Safety Reserve Coefficient of Each Horizontal Step After Soft Foundation Treatment at the +824m Horizontal Step of the Internal Waste Disposal Site in 2028 After completing the segmented and precise treatment of the soft foundation of the internal spoil heap in 2028, a plan view of the soft foundation treatment of the open-pit mine's internal spoil heap in 2028 was drawn using CAD software, based on the location of the soft foundation treatment. Figure 12 As shown.

[0034] Step S9: Repeat steps S6 to S8 until the stability of the slopes of all annual spoil heaps in the open-pit mine meets the safety reserve requirements.

[0035] In this embodiment, the location of the internal spoil heap engineering geological profile of the open-pit mine in 2029 is selected as follows: Figure 13 As shown, the engineering geological profile of the internal spoil heap is numbered 29-NP1. The engineering geological profile of the internal spoil heap is as follows: Figure 14 As shown.

[0036] In this embodiment, based on the Morgenstern-Price method, the slope stability coefficient Fs of the 2029 internal spoil heap engineering geological profile is calculated step by step from low to high according to the step level. i The calculation results are shown in Table 12. Figure 15 As shown; Table 12 Calculation Results of Slope Stability of Internal Waste Dump in 2029 In this embodiment, the predetermined threshold M is -0.005. Based on Table 12, the difference C between the stability coefficient and the safety reserve coefficient of each level step slope of the spoil heap in 2029 is calculated. i The results are shown in Table 13; Table 13 Calculation Results of the Difference Between the Stability Coefficient and the Safety Reserve Coefficient of Each Level Step Slope in the Internal Waste Disposal Site in 2029 Table 13 shows the difference C between the horizontal steps at +800m, +824m, and +848m. i The slope is less than the predetermined threshold M, therefore soft foundation treatment is required. In this embodiment, the sliding surfaces of the +800m, +824m, and +848m horizontal steps of the 2029 internal spoil heap slid along the weak layer of the 2-1 coal seam floor. Therefore, the soft foundation was treated in segments starting from the +800m horizontal step. The results of the soft foundation treatment at the +800m horizontal step are shown in Table 14. Figure 16As shown, the treatment length of the soft foundation of the +800m horizontal step is 26m. According to Table 14, calculate the difference C between the slope stability coefficient and the safety reserve coefficient of each horizontal step after the treatment of the soft foundation of the +800m horizontal step in the spoil heap in 2029. i The results are shown in Table 15.

[0037] As shown in Table 15, after the soft foundation treatment of the +800m horizontal step was completed, the difference C between the slope stability coefficient and the safety reserve coefficient of the +824m horizontal step was less than the predetermined threshold M. Therefore, soft foundation treatment is still required for the +824m horizontal step. The slope stability results after soft foundation treatment of this horizontal step are shown in Table 16. Figure 17 As shown in Table 16, the treatment length of the soft foundation of the +824m horizontal step is 10m. Based on Table 16, calculate the difference C between the slope stability coefficient and the safety reserve coefficient of each horizontal step after the treatment of the soft foundation of the +824m horizontal step in the spoil heap for 2029. i The results are shown in Table 17. Given that the difference C between the slope stability coefficient and the safety reserve coefficient of the +848m horizontal step is greater than the predetermined threshold M after the soft foundation treatment of the +824m horizontal step, the soft foundation treatment of this horizontal step will no longer be carried out.

[0038] Table 14 Calculation Results of Slope Stability After Treatment of Soft Foundation at the Internal Waste Dump + 800m Horizontal Step in 2029 Table 15 Calculation Results of the Difference Between Slope Stability Coefficient and Safety Reserve Coefficient of Each Horizontal Step After Soft Foundation Treatment at the +800m Horizontal Step of the Internal Waste Disposal Site in 2029 Table 16 Calculation Results of Slope Stability After Soft Foundation Treatment at the Internal Waste Dump +824m Horizontal Step in 2029 Table 17 Calculation Results of Slope Stability After Soft Foundation Treatment at the Internal Waste Dump +824m Horizontal Step in 2029 After completing the segmented and precise treatment of the soft foundation of the internal spoil heap in 2029, a plan view of the soft foundation treatment of the open-pit mine's internal spoil heap in 2029 was drawn using CAD software, based on the location of the soft foundation treatment. Figure 18 As shown.

[0039] The above description only illustrates the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention, and all such changes should be included within the protection scope of the present invention.

Claims

1. A closed-loop feedback design method for the segmented treatment length of soft foundation in spoil heaps, characterized in that: Includes the following steps: S1. Select and number the initial annual engineering geological profile of the open-pit mine spoil heap to be analyzed; S2. Obtain the physical and mechanical parameters of the soil and rock mass on the slope of the spoil heap; S3. Determine the safety reserve coefficient K of the spoil heap slope based on the slope service life and relevant design specifications. a ; S4. For the initial annual engineering geological profile of the spoil heap, calculate the slope stability coefficient Fs step by step from low to high according to the step level. i ; S5. Calculate the difference C between the slope stability coefficient and the safety reserve coefficient for each step. i =Fs i -K a If C i If the value is less than the predetermined threshold M, the soft substrate corresponding to this step needs to be treated in stages. If there are two or more steps that need to be treated in stages, the treatment should start from the lower level step, and the difference C between the stability coefficient and the safety reserve coefficient of each step should be recalculated after each treatment. i =Fs i -K a Until the slope stability coefficient of each step meets the reserve requirements, use CAD software to draw the plan of soft foundation treatment for that year. S6. Select and number the engineering geological profile of the spoil heap for the next year in the open-pit mine. S7. For the engineering geological profile of the spoil heap for the next year, calculate the slope stability coefficient Fs step by step from low to high according to the step level. i ; S8. Calculate the difference C between the slope stability coefficient and the safety reserve coefficient for each step. i =Fs i -K a If C i If the value is less than the predetermined threshold M, the soft substrate corresponding to this step needs to be treated in stages. If there are two or more steps that need to be treated in stages, the treatment should start from the lower level step, and the difference C between the stability coefficient and the safety reserve coefficient of each step should be recalculated after each treatment. i =Fs i -K a Until the slope stability coefficient of each step meets the reserve requirements, use CAD software to draw the plan of soft foundation treatment for that year. S9. Repeat steps S6 to S8 until the stability of the slopes of all annual spoil heaps in the open-pit mine meets the safety reserve requirements.

2. The closed-loop feedback design method for the segmented treatment length of soft foundation in a spoil heap according to claim 1, characterized in that: In steps S4 and S7, the Morgenstern-Price method is used to calculate the slope stability coefficient.

3. The closed-loop feedback design method for the segmented treatment length of soft foundation in a spoil heap according to claim 2, characterized in that: The Morgenstern-Price method for calculating slope stability coefficients is as follows: Step 1: Based on the engineering geological profile of the spoil heap, locate the soft foundation and weak coal seam, and determine the location and shape of the potential sliding surface of the slope; divide the sliding body into several vertical soil strips along the horizontal direction, numbered sequentially as i=1, 2, ..., n; input the cohesion c of the soil and rock mass corresponding to the bottom of the soil strip. i internal friction angle φ i , soil bar gravity W i α, the dip angle of the bottom surface of the soil strip i Length of the bottom surface of the soil strip l i ; Step 2: Individual soil strips bear the force. Including: the weight of the soil strip itself, W i Normal reaction force N at the bottom of the soil strip i Shear force T at the bottom of the soil strip i The inter-strip normal force E between the left side of the soil strip and the (i-1)th soil strip i-1 Inter-strip tangential force X i-1 The inter-strip normal force E between the right side of the soil strip and the (i+1)th soil strip i Inter-strip tangential force X i ; Vertical force balance: W i +X i-1 -X i =N i cosα i + T i sinα i Horizontal force balance: E i-1 -E i =N i sinα i -T i cosα i Moment balance: Taking moments about the midpoint of the bottom surface of the soil strip, the resultant moment is 0. The bottom shear force and stability coefficient satisfy: T i =(c i l i +N i tanφ i ) / Fs i Where: Fs i This refers to the slope stability coefficient. Step 3: Using the Morgenstern-Price general inter-strip force function f(x), establish the proportional relationship between the inter-strip tangential force and the normal force: X i =λ·f(x)·E i Where: λ is the inter-strip force proportionality coefficient, which is solved iteratively through equilibrium conditions; Step 4: Set the initial stability coefficient Fs i Substitute the proportionality coefficient λ into the equilibrium equation, and recursively calculate the inter-strip forces and bottom reactions from the slope toe to the slope crest; verify whether the overall force equilibrium and moment equilibrium are satisfied; correct Fs using the Newton-Raphson iteration method. i Repeat the calculation with λ until convergence, i.e., the error ≤ the preset value; the converged Fs i This is the slope stability coefficient of the profile; Step 5: Following the order of the steps from low to high, and using the top surface of each step as the calculation boundary, repeat the above steps to obtain the slope stability coefficient Fs for each horizontal step. i .

4. The closed-loop feedback design method for the segmented treatment length of soft foundation in a spoil heap according to claim 1, characterized in that: The physical and mechanical parameters mentioned in step S2 include the rock mass unit weight γ and cohesion c. i internal friction angle φ i .

5. The closed-loop feedback design method for the segmented treatment length of soft foundation in a spoil heap according to claim 1, characterized in that: The relevant design specification mentioned in step S3 is GB50197-2015 "Design Specification for Open-pit Coal Mines", and the determined safety reserve factor K a =1.

2.

6. The closed-loop feedback design method for the segmented treatment length of soft foundation in a spoil heap according to claim 1, characterized in that: The segmented treatment of the soft substrate described in steps S5 and S8 is carried out in the region where the slip surface develops along the weak layer of the coal seam top and bottom plate, and the weak layer is the weak layer of the bottom plate of coal seam 2-1.

7. The closed-loop feedback design method for the segmented treatment length of soft foundation in a spoil heap according to claim 1, characterized in that: The starting position for the segmented treatment in steps S5 and S8 is the position where the depth can be reduced to the bottom of the coal seam.

8. The closed-loop feedback design method for the segmented treatment length of soft foundation in a spoil heap according to claim 1, characterized in that: In steps S5 and S8, the segmented treatment is a step-by-step progressive treatment, meaning the steps progress from low to high. After each segment is completed, the slope stability of each step is recalculated until the C value of all steps is reached. i ≥M.

9. The closed-loop feedback design method for the segmented treatment length of soft foundation in a spoil heap according to claim 1, characterized in that: The predetermined threshold M mentioned in steps S5 and S8 is -0.005.

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