A safe and efficient method for treating suspended roof in segmented open pit and subsequent filling mining

Abstract

The present invention discloses a safe and efficient method for processing suspended tops in a segmented empty field and subsequent filling mining method, comprising the following steps: S1, judging whether the mining field has suspended tops; S2, empty area scanning: the underground mining field cooperates with the relevant personnel of the geological survey department to perform three-dimensional laser scanning on the mining field and the surrounding tunnels; S3, arranging data: processing the three-dimensional laser scanning data on the software and integrating the mining field monomer design CAD drawing on the DIMINE software for drawing; S4, analyzing the model: combining the "mining field design model" and the "tunnel model" with the "three-dimensional empty area model" to analyze the appropriate hole filling scheme, and using the mining section function of the DIMINE software to directly design the most appropriate hole filling and blasting design on the software; S5, on-site verification: the surveyor lays out the line on-site according to the hole filling design; S6, the perforating trolley fills the hole: the perforating trolley reports the operation status of the day in each shift. The present invention eliminates the need for operators to perform perforating operations above the empty area, greatly improving the safety of the working environment.

Description

Technical Field

[0001] The invention relates to the technical field of mine production, in particular to a safe and efficient method for processing suspended roofs in a segmented empty field and subsequent filling mining method. Background Art

[0002] The N3 ore body of the copper-sulfur-gold ore belt in the ninth area of ​​Yinshan Mine is mainly distributed in non-karst areas. The top and bottom surrounding rocks are mainly phyllite, which is foliated. In addition, due to the fault and fold geological structure of some mining areas, it is easy to cause hanging roof during deep hole blasting.

[0003] At present, the main reasons for deep hole blasting overhang are:

[0004] 1. Construction quality. The cutting height and hole depth parameters did not meet the design requirements, and the row spacing was too large;

[0005] 2. Medium and deep hole blasting quality. The explosive quality and charge density do not meet the requirements;

[0006] 3. Geological factors: The ore body has complex occurrence conditions, such as the development of rock foliation, faults and folded geological structures, etc.

[0007] The traditional method of using total station and visual inspection to solve the problem of deep hole blasting hanging top has two prominent problems:

[0008] 1) Operators are likely to perform drilling operations above the empty area, which poses a great safety hazard;

[0009] 2) The blasting parameters for suspended roof holes cannot be accurately designed, resulting in a low success rate for suspended roof treatment. Summary of the invention

[0010] The purpose of the present invention is to solve the above technical problems. The present application uses "DIMINE software" and "3D laser scanner" to jointly process the deep hole blasting hanging top, which can improve the safety of the working environment and avoid the large amount of ore loss caused by the deep hole blasting hanging top, thereby improving the economic benefits.

[0011] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0012] The present invention provides a safe and efficient method for treating the suspended roof in a segmented empty field and subsequent filling mining method.

[0013] The following steps are involved:

[0014] S1 Determine whether the mine is suspended: After the mine is empty, deal with the loose rocks on the top and sides of the mine area to ensure safety and make a preliminary analysis of the on-site situation. If the mine area does not penetrate the upper section or the height of the mine area obviously does not reach the designed height, the mine is judged to be suspended. After determining that the mine is suspended, immediately contact the geological survey department to scan the mine area;

[0015] S2 Scanning of empty areas: The underground mining site cooperates with the relevant personnel of the geological survey department to conduct 3D laser scanning of the empty areas and surrounding tunnels. When scanning the empty areas, the "3D laser scanner" can be fixed by drones or telescopic poles, and the scanner can be extended into the empty areas to scan back and forth. To ensure that the outline of the empty areas is clear and accurate, the scanner needs to be scanned repeatedly in the empty areas. After scanning the empty areas, the tunnels around the empty areas of the mining site also need to be scanned to facilitate the design of the patch holes. Finally, the scanner is used to scan the nearby control points to facilitate the positioning of the map;

[0016] S3 data collection: 3D laser scanning data is processed on the software and the mining site monomer design CAD Figure 1 And integrate it into DIMINE software for drawing;

[0017] S4 analysis model: Combine the "stope design model" and "tunnel model" with the "3D void area model" to analyze the appropriate hole-filling scheme, and use the mining section function of DIMINE software to directly design the most appropriate hole-filling and blasting design in the software;

[0018] S5 On-site verification: Surveyors lay out the holes on-site according to the hole patching design, and adjust the hole patching design according to the actual situation on site;

[0019] S6 perforating trolley hole filling: The perforating trolley reports the day's work status every shift. If there is a special situation where the drilling deviation rate is too large or the drilling is too deep, resulting in the penetration of the upper empty area, the technical staff must be contacted immediately to adjust the design.

[0020] Optionally, the "mine design model" in S4 is a three-dimensional digital model that rationally plans and designs the location, shape, size, and sequence of the mine according to the occurrence characteristics of the ore body and mining conditions. The mine design model can intuitively reflect the spatial layout of the mine and the mining effect, and provide a basis for the selection and optimization of mining methods.

[0021] Optionally, the “lane model” in S4 is a digital model that performs three-dimensional modeling of the geometric shape and engineering structure of the lane according to the position, direction, section, and length parameters of the lane. The lane model can clearly display the spatial position and mutual relationship of the lane, and provide a reference for the design, construction, and management of the lane;

[0022] Optionally, the S4 "three-dimensional void area model" is a three-dimensional digital model that uses a laser scanner or drone equipment to accurately measure and record the shape and size of the goaf. The three-dimensional void area model can truly reflect the actual situation of the goaf and provide data support for the management, monitoring and evaluation of the goaf.

[0023] Optionally, the S4 combines the “stope design model” and the “tunnel model” with the “three-dimensional void area model” to analyze a suitable hole-filling scheme, including the following steps:

[0024] 1) Import the "stope design model" and "tunnel model" into professional mining software, such as DIMINE, to generate a complete 3D mine model, including ore body, tunnel, stope, and ventilation information;

[0025] 2) Compare and match the "3D goaf model" with the 3D mine model to find out the differences between the goaf and the design model, such as over-excavation, under-excavation, and hanging roof, and mark the location and range of the holes that need to be filled;

[0026] 3) Using the plugging hole design function of the mining software, determine the plugging hole parameters, such as plugging hole position, direction, depth, spacing, hole diameter, charge amount, and detonation sequence, according to the shape, size, location, and stability factors of the goaf;

[0027] 4) Use the blasting simulation function of the mining software to predict the effect of the hole-filling blasting, such as the blasting network, blasting method, blasting time, and blasting effect, evaluate the rationality and safety of the hole-filling scheme, and adjust and optimize the hole-filling scheme if necessary;

[0028] 5) The hole-patching plan is exported to the site, where surveyors will lay out and check the lines, and the perforating trolley will carry out hole-patching and charge loading. Blasting will be carried out according to the designed detonation sequence to complete the hole-patching operation.

[0029] Optionally, in the S2 empty area scanning step, the "three-dimensional laser scanner" is a rotatable, retractable, and angle-adjustable scanner that can automatically adjust scanning parameters according to the shape and size of the empty area to improve scanning efficiency and accuracy.

[0030] Optionally, in the S5 on-site verification step, the surveyor uses a wireless electronic measuring instrument that can interact with the DIMINE software for data, provide real-time feedback on the on-site hole patching situation, and fine-tune and optimize the hole patching design according to the guidance and suggestions of the software.

[0031] Optionally, in the S6 perforating trolley hole patching step, the perforating trolley is an automated hole patching device that can automatically locate, drill, load and seal holes according to the hole patching plan of the DIMINE software, and has automatic detection, automatic alarm and automatic stop functions, which can effectively avoid misoperation and dangerous situations during the hole patching process.

[0032] Beneficial effects of the present invention

[0033] The present invention eliminates the need for operators to perform drilling operations above the empty area, thus greatly improving the safety of the working environment;

[0034] The traditional perforation method is easy to cause medium-deep holes to be punched through, resulting in a high blind shot rate; the new improved method does not have the phenomenon of medium-deep holes being punched through, and the blind shot rate is low;

[0035] The traditional method of dealing with suspended roof perforations has a large amount, a high penetration rate, and a large amount of drug leakage. The new improved method has a small perforation amount, an extremely low penetration rate, and a small amount of drug leakage. Its efficiency is 1.94 times that of the traditional method, which greatly improves the recovery efficiency and reduces safety risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 For the establishment of the DIMINE model.

[0037] Figure 2 , Figure 3 This is the before and after plan for scanning the -343m segment N3 / 6-7 empty area.

[0038] Figure 4 It is the -343m segment N3 / 7-4 patch hole location.

[0039] Figure 5 Designed for some gun platoons.

[0040] Figure 6 This is the design of the positive row inclined hole profile for the N3 / 7-4 section at -343m.

[0041] Figure 7 For on-site verification.

[0042] Figure 8 Perforate the trolley.

[0043] Fig. 9 This is the -343m section N3 / 6-7 before and after the roof treatment.

[0044] Fig.10 This is the DIMINE model diagram before and after the suspended ceiling treatment.

[0045] Fig.11 This is the blasting stress cloud diagram at 0.54ms.

[0046] Fig.12 This is the blasting stress cloud diagram at 0.94ms. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] Example

[0049] The present invention provides a safe and efficient method for treating the suspended roof in a segmented empty field and subsequent filling mining method.

[0050] The following steps are involved:

[0051] S1 Determine whether the mine is suspended: After the mine is empty, deal with the loose rocks on the top and sides of the mine area to ensure safety and make a preliminary analysis of the on-site situation. If the mine area does not penetrate the upper section or the height of the mine area obviously does not reach the designed height, the mine is judged to be suspended. After determining that the mine is suspended, immediately contact the geological survey department to scan the mine area;

[0052] S2 Scanning of empty areas: The underground mining site cooperates with the relevant personnel of the geological survey department to conduct 3D laser scanning of the empty areas and surrounding tunnels. When scanning the empty areas, the "3D laser scanner" can be fixed by drones or telescopic poles, and the scanner can be extended into the empty areas to scan back and forth. To ensure that the outline of the empty areas is clear and accurate, the scanner needs to be scanned repeatedly in the empty areas. After scanning the empty areas, the tunnels around the empty areas of the mining site also need to be scanned to facilitate the design of the patch holes. Finally, the scanner is used to scan the nearby control points to facilitate the positioning of the map;

[0053] S3 data collection: 3D laser scanning data is processed on the software and the mining site monomer design CAD Figure 1 And integrate it into DIMINE software for drawing;

[0054] S4 analysis model: Combine the "stope design model" and "tunnel model" with the "3D void area model" to analyze the appropriate hole-filling scheme, and use the mining section function of DIMINE software to directly design the most appropriate hole-filling and blasting design in the software;

[0055] S5 On-site verification: Surveyors lay out the holes on-site according to the hole patching design, and adjust the hole patching design according to the actual situation on site;

[0056] S6 perforating trolley hole filling: The perforating trolley reports the day's work status every shift. If there is a special situation where the drilling deviation rate is too large or the drilling is too deep, resulting in the penetration of the upper empty area, the technical staff must be contacted immediately to adjust the design.

[0057] The "mine design model" in S4 is a three-dimensional digital model that rationally plans and designs the location, shape, size, and sequence of the mine based on the occurrence characteristics of the ore body and mining conditions. The mine design model can intuitively reflect the spatial layout of the mine and the mining effect, and provide a basis for the selection and optimization of mining methods.

[0058] The "lane model" in S4 is a digital model that performs three-dimensional modeling of the geometric shape and engineering structure of the lane according to the location, direction, section, and length parameters of the lane. The lane model can clearly display the spatial location and mutual relationship of the lane, and provide a reference for the design, construction, and management of the lane;

[0059] The S4 "three-dimensional void area model" is a three-dimensional digital model that uses laser scanners or drone equipment to accurately measure and record the shape and size of the void area. The three-dimensional void area model can truly reflect the actual situation of the void area and provide data support for the management, monitoring and evaluation of the void area.

[0060] In S4, the “stope design model” and “tunnel model” are combined with the “three-dimensional void area model” to analyze a suitable hole-filling scheme, including the following steps:

[0061] 1) Import the "stope design model" and "tunnel model" into professional mining software, such as DIMINE, to generate a complete 3D mine model, including ore body, tunnel, stope, and ventilation information;

[0062] 2) Compare and match the "3D goaf model" with the 3D mine model to find out the differences between the goaf and the design model, such as over-excavation, under-excavation, and hanging roof, and mark the location and range of the holes that need to be filled;

[0063] 3) Using the plugging hole design function of the mining software, determine the plugging hole parameters, such as plugging hole position, direction, depth, spacing, hole diameter, charge amount, and detonation sequence, according to the shape, size, location, and stability factors of the goaf;

[0064] 4) Use the blasting simulation function of the mining software to predict the effect of the hole-filling blasting, such as the blasting network, blasting method, blasting time, and blasting effect, evaluate the rationality and safety of the hole-filling scheme, and adjust and optimize the hole-filling scheme if necessary;

[0065] 5) The hole-patching plan is exported to the site, where surveyors will lay out and check the lines, and the perforating trolley will carry out hole-patching and charge loading. Blasting will be carried out according to the designed detonation sequence to complete the hole-patching operation.

[0066] In the S2 empty area scanning step, the "three-dimensional laser scanner" is a rotatable, retractable, and angle-adjustable scanner that can automatically adjust scanning parameters according to the shape and size of the empty area to improve scanning efficiency and accuracy;

[0067] In the S5 on-site verification step, the surveyor uses a wireless electronic measuring instrument that can interact with the DIMINE software to provide real-time feedback on the on-site hole filling situation, and fine-tune and optimize the hole filling design according to the guidance and suggestions of the software;

[0068] In the S6 perforating trolley hole-filling step, the perforating trolley is an automated hole-filling device that can automatically locate, drill, charge, and seal holes according to the hole-filling scheme of the DIMINE software. It also has automatic detection, automatic alarm, and automatic stop functions, which can effectively avoid misoperation and dangerous situations during the hole-filling process;

[0069] Here are some examples:

[0070] -343m segment N3 / 7-4 DIMINE model as Figure 1 As shown, the position and range of the suspended ceiling can be clearly seen from the figure.

[0071] In order to further verify the effect of this method in dealing with suspended ceilings, numerical simulation was used to simulate and verify the hole-filling scheme.

[0072] The first step is to determine the key parameters, which include:

[0073] 1) Unit algorithm determination

[0074] When using LS-DYNA to numerically simulate the explosion process, in order to avoid the numerical calculation difficulties caused by large deformation and improve the calculation efficiency, ALE grid can be used to divide the explosive entity and Lagrange grid can be used for rock and filling materials. This simulation experiment uses fluid-solid coupling algorithm and three-dimensional model to perform numerical calculations on the blasting process of this study.

[0075] 2) Determination of material parameters

[0076] ① Rock material model and parameters

[0077] The plastic dynamics model *MAT_PLASTIC_KINEMATIC used in this numerical simulation is an isotropic, kinematic hardening or a mixed model of isotropic and kinematic hardening. It is strain rate-dependent and very suitable for rock materials in explosion analysis. Table 1 gives the material parameters of the ore body model.

[0078]

[0079] Table 1 Ore body model material parameters

[0080] ② Explosive material model and parameters

[0081] This numerical simulation calculation uses the No. 2 rock emulsion explosive commonly used in underground mine blasting, and selects the LS-DYNA3D internal high-energy material constitutive model MAT_HIGH_EXPLOSIVE_BURN. The specific parameters are shown in Table 2.

[0082]

[0083] Table 2 Material parameters of explosives and JWL state equation parameters of explosives

[0084] Analysis of numerical simulation results

[0085] from Figure 11-12 It can be seen that at t=0.54ms, the explosion stress wave of the middle blast hole reaches the vicinity of the free surface and generates a reflected tensile stress wave. The free surface rock mass receives the reflected tensile stress wave and begins to undergo tensile failure, which develops toward the blast hole. At t=0.94ms, the reflected tensile stress wave propagates to the vicinity of the middle blast hole, causing the destruction of the rock mass from the blast hole to the free surface. It can be seen that the hole-filling scheme has achieved a relatively ideal blasting effect.

[0086] Industrial trials

[0087] This project selects the representative N3 / 6-7 and 7-4 as examples to introduce the use of "DIMINE software" and "3D laser scanner" to jointly deal with the deep hole blasting hanging top. And analyzes them from the perspectives of safety and economy.

[0088] Hole patching design

[0089] Safety: -343m segment N3 / 6-7 empty area scanning before and after plan as follows Figure 2 , Figure 3 As shown;

[0090] The plan before scanning the empty area was to drill an oblique hole in the 6-3 drilling tunnel to 6-7 to blast the suspended roof. If the empty area was not scanned, the workers would perform drilling operations above the empty area, which would pose a serious safety hazard. After scanning, it was found that the mining area had collapsed to the 6-3 drilling tunnel. The design was modified to divert the route at the location shown in the figure and drill an oblique hole, successfully dealing with the suspended roof.

[0091] Economic aspect: -343m segment N3 / 7-4 patching position and gun row design Figure 4 , 5 The parameters of the blasting are shown in Table 3. DIMINE can be used to accurately and quickly design the parameters of each row of blast holes.

[0092]

[0093] Table 3 Parameters of hole filling blasting

[0094] -343m segment N3 / 7-4 suspended roof 7 rows, due to the decreasing effect of blasting space, the height of the suspended roof will become thicker and thicker, the loss rate of subsequent blasting rows will gradually increase, and the grade of the N3 / 7 line mining area is high and the thickness is large. If the suspended roof is not treated, the economic loss will be huge. Use the air area scanner to determine the range of the suspended roof, and get Figure 6Through DIMINE, the boundary of the empty area can be accurately cut out, and the most reasonable angle of the inclined hole and the length of the charge can be designed.

[0095] On-site verification reference Figure 7 .

[0096] Arrange trolley perforation reference Figure 8 .

[0097] Results analysis reference Fig. 9 .

[0098] The on-site blasting effect of the hole filling design obtained by combining "DIMINE software" and "3D laser scanner" is as follows Fig. 9 By checking that the ore output on that day was significantly greater than the ore collapse in the stope, it can be seen that the hanging roof has been dealt with. As can be seen from the figure, the blasting effect is good, the goaf formed after the blasting is basically consistent with the design, the formation is good, the ore is not depleted, and a relatively ideal effect has been achieved.

[0099] To further understand the treatment of suspended ceilings, DIMINE was used to establish Fig.10 The model shown is of the suspended roof before and after treatment. It can be clearly seen from the model that the suspended roof has exploded.

[0100] The present invention eliminates the need for operators to perform drilling operations above the empty area, thus greatly improving the safety of the working environment;

[0101] The traditional perforation method is easy to cause medium-deep holes to be punched through, resulting in a high blind shot rate; the new improved method does not have the phenomenon of medium-deep holes being punched through, and the blind shot rate is low;

[0102] The traditional method of dealing with suspended roof perforations has a large amount, a high penetration rate, and a large amount of drug leakage. The new improved method has a small perforation amount, an extremely low penetration rate, and a small amount of drug leakage. Its efficiency is 1.94 times that of the traditional method, which greatly improves the recovery efficiency and reduces safety risks.

[0103] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A safe and efficient method for treating suspended roof in a segmented empty field and subsequent filling mining method, characterized in that: The following steps are involved: S1 Determine whether the mine is suspended: After the mine is empty, deal with the loose rocks on the top and sides of the mine area to ensure safety and make a preliminary analysis of the on-site situation. If the mine area does not penetrate the upper section or the height of the mine area obviously does not reach the designed height, the mine is judged to be suspended. After determining that the mine is suspended, immediately contact the geological survey department to scan the mine area; S2 Scanning of empty areas: The underground mining site cooperates with the relevant personnel of the geological survey department to conduct 3D laser scanning of the empty areas and surrounding tunnels. When scanning the empty areas, the "3D laser scanner" can be fixed by drones or telescopic poles, and the scanner can be extended into the empty areas to scan back and forth. To ensure that the outline of the empty areas is clear and accurate, the scanner needs to be repeatedly scanned in the empty areas for many times. After scanning the empty areas, the tunnels around the empty areas of the mining site also need to be scanned to facilitate the design of the patch holes. Finally, the scanner is used to scan the nearby control points to facilitate the positioning of the map; S3 Data collation: The 3D laser scanning data is processed on the software and the CAD drawings of the stope unit are integrated into the DIMINE software for drawing; S4 analysis model: Combine the "stope design model" and "tunnel model" with the "3D void area model" to analyze the appropriate hole-filling scheme, and use the mining section function of DIMINE software to directly design the most appropriate hole-filling and blasting design in the software; S5 On-site verification: Surveyors lay out the holes on-site according to the hole patching design, and adjust the hole patching design according to the actual situation on site; S6 perforating trolley hole filling: The perforating trolley reports the day's operation status every shift. If there is a special situation where the drilling deviation rate is too large or the drilling is too deep, resulting in the upper empty area being penetrated, the technical staff must be contacted immediately to adjust the design; The "stope design model" in step S4 is a three-dimensional digital model for rationally planning and designing the location, shape, size, and sequence of the stope according to the occurrence characteristics of the ore body and the mining conditions. The stope design model can intuitively reflect the spatial layout and mining effect of the stope, and provide a basis for the selection and optimization of the mining method; The "lane model" in step S4 is a digital model that performs three-dimensional modeling of the geometric shape and engineering structure of the lane according to the position, direction, section and length parameters of the lane. The lane model can clearly show the spatial position and mutual relationship of the lane, and provide a reference for the design, construction and management of the lane; The step S4 "three-dimensional void area model" is a three-dimensional digital model that uses a laser scanner or unmanned aerial vehicle equipment to accurately measure and record the shape and size of the void area. The three-dimensional void area model can truly reflect the actual situation of the void area and provide data support for the management, monitoring and evaluation of the void area; In step S4, the "stope design model" and "tunnel model" are combined with the "three-dimensional void area model" to analyze a suitable hole-filling scheme, which includes the following steps: 1) Import the "stope design model" and "tunnel model" into the professional mining software DIMINE to generate a complete 3D mine model, including ore body, tunnel, stope and ventilation information; 2) Compare and match the "3D void area model" with the 3D mine model to find out the differences between the goaf and the design model in terms of over-excavation, under-excavation, and hanging roof, and mark the location and range of the holes that need to be filled; 3) Using the plugging hole design function of the mining software, determine the plugging hole parameters according to the shape, size, location and stability factors of the goaf, including the plugging hole location, direction, depth, spacing, hole diameter, charge amount and detonation sequence; 4) Use the blasting simulation function of the mining software to predict the effect of the patching blasting, and evaluate the rationality and safety of the patching scheme based on the blasting network, blasting method, blasting time, and blasting effect; 5) The hole-patching plan is exported to the site, where surveyors will lay out and check the lines, and the perforating trolley will carry out hole-patching and charge loading. Blasting will be carried out according to the designed detonation sequence to complete the hole-patching operation.

2. A safe and efficient method for treating suspended roof in a segmented empty pit and subsequent filling mining method according to claim 1, characterized in that: In the empty area scanning step S2, the "three-dimensional laser scanner" is a rotatable, retractable, and angle-adjustable scanner that can automatically adjust scanning parameters according to the shape and size of the empty area to improve scanning efficiency and accuracy.

3. A safe and efficient method for treating suspended roof in a segmented empty pit and subsequent filling mining method according to claim 1, characterized in that: In the on-site verification step S5, the surveyor uses a wireless electronic measuring instrument that can interact with the DIMINE software to provide real-time feedback on the on-site hole filling situation, and fine-tune and optimize the hole filling design according to the guidance and suggestions of the software.

4. A safe and efficient method for treating suspended roof in a segmented empty pit and subsequent filling mining method according to claim 1, characterized in that: In the step S6 of the perforating trolley hole filling step, the perforating trolley is an automated hole filling device that can automatically position, drill, load and seal holes according to the hole filling plan of the DIMINE software. It also has automatic detection, automatic alarm and automatic stop functions, which can effectively avoid misoperation and dangerous situations during the hole filling process.

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