Blasting energy-releasing supporting and tunneling method for ultra-deep vertical shaft step of metal mine

Abstract

The invention provides a metal mine ultra-deep vertical shaft step blasting energy release support tunneling method, and belongs to the technical field of metal mine ultra-deep vertical shaft energy release support. Dividing different-depth horizontal surrounding rock mass quality grades of the shaft according to the engineering geological information and evaluating different-depth surrounding rock rockburst tendency grades of the shaft; according to the engineering geological information, shaft circulation excavation sections are divided, and shaft drilling and blasting parameters are determined; according to the engineering geological information and the rockburst tendency grade, a stepped excavation construction mode is determined, and a supporting mode and supporting parameters are determined; loading rock and discharging slag; and the concrete lining permanent supporting opportunity is obtained, and anchor net shotcreting temporary supporting and concrete lining permanent supporting are conducted on the ultra-deep vertical shaft. Through the combination form of bench blasting and temporary supporting, in a deep high-stress unstable stratum area, surrounding rock pressure is released, rock mass dynamic impact is absorbed, the risk of rock burst disasters is reduced, and the shaft construction safety is improved.

Description

Technical Field

[0001] This application belongs to the technical field of energy-releasing support for ultra-deep vertical shafts in metal mines, and specifically relates to a method for energy-releasing support tunneling by bench blasting in ultra-deep vertical shafts of metal mines. Background Technique

[0002] As a key transportation route connecting the surface and underground projects, the construction period of vertical shafts accounts for 30% - 55% of the total construction period of the mine. With the increase in the mining depth of the mine, the construction depth of the shaft also increases. The deep shaft is under the environmental conditions of "high stress, high temperature, high water pressure and disturbance". The formation conditions are complex, the deformation and failure of the shaft are significantly aggravated, the ground pressure appears strongly, and underground disasters such as shaft rock bursts and high-pressure water inrusions occur frequently. It is difficult to cope with the deep engineering disasters by using conventional construction techniques and support means. It is necessary to adopt correct and effective shaft pressure-relief construction techniques to control the stability of the shaft surrounding rock, so that the vertical shaft project can be safely, efficiently and smoothly excavated and lined to the bottom. This is the key for the mining of mine resources to move from the shallow part to the deep part.

[0003] At present, the vertical shaft construction technology mainly focuses on the blasting shaft-sinking method. This method has the characteristics of mature technology, flexibility, high efficiency and strong applicability. On-site engineering personnel can flexibly adjust the blasting parameters according to the engineering conditions to achieve the best blasting effect. The shaft blasting design needs to reasonably arrange the drilling holes according to the shaft size, the characteristics of the penetrated strata, the engineering geological conditions, the type and parameters of explosives. Affected by the rock properties, the specific consumption of explosives and detonators is positively correlated with the rock Prandtl coefficient. According to the essence of the blasting process, deep-hole blasting to form a shaft can be divided into the cut method and the funnel method. Due to the disadvantages of complex construction technology and difficult implementation of the funnel method, the cut method is generally used for shaft blasting tunneling. The quality of the cut has a decisive effect on the shaft cycle footage. The cut forms are mainly divided into parallel-hole cut and inclined-hole cut. The parallel-hole cut is preferred in blasting tunneling because of its simple design, not being restricted by the section size, easy operation, and obvious improvement in construction speed when combined with mechanized rock drilling equipment. According to the statistics of relevant scholars, the parallel-hole cut accounts for more than 80% of the vertical shaft blasting tunneling project, which is the first choice in blasting tunneling. The difference between the cut holes and the non-cut holes is the ultra-deep depth. According to statistics, the ultra-deep depth in vertical shaft blasting is generally 200mm, accounting for 67% of the statistical cases; the depth of the perimeter holes in vertical shaft blasting is mainly the single-cycle blast holes of 3 - 5m, accounting for 70%. The deep blasting technology is the key for the shaft drill-and-blast method to efficiently tunnel.

[0004] Due to the disturbance of blasting excavation in ultra - deep shafts, the original rock stress balance is broken, and the stress redistributes and adjusts. The stress state of the shaft surrounding rock is related not only to the initial stress state of the rock mass before excavation, the shape of the shaft, and the physical and mechanical properties of the rock mass, but also to factors such as construction technology and support structure. When the disturbance stress during the excavation of the ultra - deep shaft exceeds the uniaxial compressive strength of the rock, the shaft surrounding rock will undergo brittle failures of different natures in a stable or unstable manner. That is, the disaster - causing process of the ultra - deep shaft excavation disturbance is directly related to the failure response of the rock mass under high - stress action, especially the displacement change and the high - strain energy storage state of the rock mass after the shaft excavation.

[0005] Blasting pressure relief is an effective means for controlling the surrounding rock of high - stress and strongly - excavated shafts. According to the principle of loose blasting pressure relief, by creating a certain deformation space in the shallow surrounding rock, the displacement of the surrounding rock towards the shaft space is reduced, and the high stress in the shallow surrounding rock is transferred to the deep part. There are two layout methods for the blasting holes in the shaft: the stepped type and the full - section type. First, with the improvement of the vertical drilling accuracy, the full - section layout method of vertical holes is widely used, enabling the shaft section to be detonated at one time. However, this method cannot release the stress of the shaft surrounding rock in advance, nor can it transfer and disperse the concentrated stress. Second, the stepped layout method creates a deformation space for the shaft surrounding rock, changes the size of the local surrounding rock, reduces the transfer of the surrounding rock towards the shaft space, and at the same time forms a local stress field, reducing the concentrated stress inside the surrounding rock. During the stress redistribution process, the radial stress of the shaft surrounding rock decreases in a stepped manner with the stepped excavation, transferring the high stress in the shallow surrounding rock to the deep part and expanding the bearing range of the surrounding rock. However, in complex and difficult ultra - deep shafts dominated by stress, relying solely on means such as strengthening the support strength, density, and secondary support is not enough to effectively release the stress of the surrounding rock. Summary of the Invention

[0006] Therefore, the purpose of this application is to provide a stepped - blasting energy - releasing support tunneling method for ultra - deep shafts in metal mines, which solves at least one technical problem mentioned in the background technology.

[0007] To solve the above problems, this application provides a stepped - blasting energy - releasing support tunneling method for ultra - deep shafts in metal mines, including: Obtain the engineering geological information of the excavation area of the ultra - deep shaft, and divide the rock mass quality grades of the surrounding rock at different depths of the shaft according to the engineering geological information and evaluate the rock burst proneness grades of the surrounding rock at different depths of the shaft; Divide the cyclic excavation sections of the shaft according to the engineering geological information and determine the shaft drilling and blasting parameters; Determine the stepped excavation construction method according to the engineering geological information and the rock burst proneness grade; Conduct energy - releasing support design for the ultra - deep shaft according to the engineering geological information and the rock burst proneness grade, and determine the support method and support parameters; Load and muck out the rock. Obtain the timing of permanent support for the concrete lining, and conduct temporary support of bolting with wire mesh and shotcreting and permanent support of concrete lining for the ultra-deep shaft.

[0008] Optionally, the steps of obtaining the engineering geological information of the excavation area of the ultra-deep shaft, dividing the rock mass quality grade of the shaft wall rock and evaluating the rockburst proneness grade of the rock at different depths of the shaft include: Record the engineering geological information of the core of the engineering exploration hole; obtain the engineering geological information of the shaft wall rock exposed during the excavation of the shaft; evaluate the engineering geological information of the excavation area of the ultra-deep shaft according to the engineering geological information of the exposed shaft wall rock and the engineering geological information of the core of the engineering exploration hole; According to the engineering geological information, classify the rock mass quality at different depths of the shaft into grades by using the Barton rock mass quality index Q classification method, the rock mass geomechanics RMR classification method and the geological strength index GSI classification method; According to the engineering geological information, conduct comprehensive analysis by using the brittleness coefficient method, Barton method and stress-strength method to obtain the rockburst proneness grade of the surrounding rock of the ultra-deep shaft.

[0009] Optionally, the steps of dividing the shaft cyclic excavation section and determining the shaft rock drilling and blasting parameters according to the engineering geological information include: According to the engineering geological information, divide the ultra-deep shaft into N cyclic excavation sections, where N is a positive integer; According to the engineering geological information, use smooth surface, smooth bottom, weak vibration and weak impact short-hole blasting technology to determine the shaft rock drilling and blasting parameters.

[0010] Optionally, the steps of determining the stepped excavation construction method according to the engineering geological information and the rockburst proneness grade include: According to the engineering geological information and the rockburst proneness grade, divide the cross-section of each cyclic excavation section of the shaft into two steps; the excavation footage between two adjacent in-shaft steps in each cyclic excavation section is one lining section height; wherein, the lining section height is 2m to 4m.

[0011] Optionally, when using smooth surface, smooth bottom, weak vibration and weak impact short-hole blasting technology to determine the shaft rock drilling and blasting parameters, the shaft rock drilling and blasting parameters include explosive consumption, cartridge diameter and hole diameter, hole depth, number of holes and hole layout.

[0012] Optionally, the explosive consumption is an important parameter to measure the shaft rock drilling and blasting effect. Therefore, the explosive consumption The calculation formula is: Q 炸药 =qSLη; Wherein, q is the unit explosive consumption; S is the cross-sectional area of the shaft excavation; L is the average depth of the blast holes; η is the utilization rate of the blast holes; The calculation formula for the number of blast holes is: ; Substituting the calculation formula for explosive consumption into the calculation formula for the number of blast holes, we get: ; Wherein, Q 炸药 is the explosive consumption; N is the number of blast holes; a is the charging coefficient (a = 0.5 - 0.7); p is the mass of each cartridge; m is the length of each cartridge.

[0013] Optionally, in the ultra - deep shaft blasting construction, the blast hole arrangement method includes: Determine the form and number of the cut holes and arrange the cut holes; Determine the number of the perimeter holes and arrange the perimeter holes; Determine the number of circles and the number of the auxiliary holes and arrange the auxiliary holes.

[0014] Optionally, the steps of determining the support method and support parameters for the ultra - deep shaft through energy - releasing support design according to the engineering geological information and the rockburst proneness level include: According to the different rockburst grades of the surrounding rock of the ultra - deep shaft and the action mechanism of the support system, preliminarily determine the composition of the support system; According to different rockburst mechanisms and rockburst grades, calculate three support indexes: the load safety factor, the displacement safety factor, and the energy safety factor of the support system; According to the rockburst mechanism, rockburst grade and support indexes, determine the final composition of the support system and calculate the support system parameters.

[0015] Optionally, the steps of calculating the load safety factor, the displacement safety factor, and the energy safety factor of the support system according to different rockburst mechanisms and rockburst grades include: The calculation formula for the load safety factor is: ; The calculation formula for the displacement safety factor is: ; The calculation formula for the energy safety factor is: .

[0016] Optionally, the steps of calculating the support system parameters include: Obtain the energy on the surface of the shaft surrounding rock during rockburst and obtain the energy released per unit area of the bolt; according to the energy released per unit area of the bolt being greater than the energy on the surface of the shaft surrounding rock during rockburst, calculate the row spacing of the bolt support; Obtain the shaft span and the RMR value; calculate the bolt length according to the shaft span and the RMR value.

[0017] Optionally, the steps of mucking and slag discharging include: Carry out sectional mucking, mucking and leveling the bottom of the shaft face on the shaft working face; When the slag discharging height on the shaft working face reaches the height of the excavation and lining section, level the slag surface on the shaft circumference.

[0018] Optionally, the steps of obtaining the timing of permanent concrete lining support and carrying out temporary bolt-shotcrete support and permanent concrete lining support for the ultra-deep shaft include: Determine the timing of permanent concrete lining support by means of the stability chart of RMR rock mass geomechanics classification or by on-site ground pressure monitoring means to obtain the evolution process of the surrounding rock pressure of the deep shaft excavation shaft; Carry out temporary bolt-shotcrete support and permanent concrete lining support for the ultra-deep shaft according to the timing of permanent concrete lining support.

[0019] By means of the above technical solutions, the invention of the present application has at least the following beneficial effects: A stepped blasting energy release support tunneling method for ultra-deep shafts in metal mines provided by an embodiment of the present application is mainly applicable to large-diameter ultra-deep shafts with a well depth of more than 1200 m. Due to the high well depth of ultra-deep shafts, the deep stress is large and the surrounding rock has high energy, which is prone to impact ground pressure disasters such as rock bursts, threatening the stability of ultra-deep shafts. Through the combination of stepped blasting and temporary support, the comprehensive pressure relief and support capabilities of stepped excavation and energy release bolt support can be fully utilized. In the area of deep high-stress unstable strata, the surrounding rock pressure can be released, the dynamic impact of the rock mass can be absorbed, the risk of rock burst disasters can be reduced, and the construction safety of the shaft can be improved. At the same time, the impact and damage of the blasting shock wave and seismic wave on the shaft wall and other building facilities are also reduced, a free face is added for the next-stage blasting excavation, the quality and safety of the shaft blasting construction are improved, the on-site construction cost is reduced, and the shaft construction progress is accelerated. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a flow chart of the stepped blasting energy release support tunneling method for ultra-deep shafts in metal mines according to an embodiment of the present application; Figure 2 is the blast hole layout Figure 1 ; Figure 3 is the blast hole layout Figure 2 。

[0021] The reference signs are shown as: 1, upper bench; 2, lower bench; 3, cut hole; 4, auxiliary hole; 5, perimeter hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0023] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0024] In the present application, unless otherwise clearly specified and limited, terms such as "installed", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0026] The present application adopts the step blasting pressure relief tunneling technology, combines stepped excavation with energy release support, conducts engineering surveys on ultra-deep vertical shafts to understand the formation lithology, divide the rock mass quality grades, and evaluate the rock burst proneness of the strata at different depths of the shaft, realizing the transparency of the surrounding rock of the ultra-deep vertical shaft to achieve the purpose of pressure relief construction and safe and efficient construction of ultra-deep vertical shafts.

[0027] Combined with reference to Figure 1 As shown, according to an embodiment of the present application, there is provided a method for step blasting energy release support tunneling of an ultra-deep vertical shaft in a metal mine, including the following steps: Step S1, obtaining the engineering geological information of the excavation area of the ultra-deep vertical shaft, and dividing the rock mass quality grades of the surrounding rock of the shaft at different depths horizontally and evaluating the rock burst proneness grades of the surrounding rock of the shaft at different depths. Specifically, it includes: Step S11: Catalog the engineering geological information of the core samples from the engineering geological exploration boreholes; obtain the engineering geological information of the shaft surrounding rock exposed during the shaft excavation; evaluate the engineering geological information of the ultra-deep shaft excavation area based on the engineering geological information of the exposed shaft surrounding rock and the engineering geological information of the core samples from the engineering geological exploration boreholes. Specifically: Catalog the engineering geological information of the core samples from the engineering geological exploration boreholes, including cataloging information such as rock information, structural plane information, and structural plane filling materials, etc.; the rock information includes rock color, weathering degree, rock structure, spacing of rock structural planes, hardness, rock lithology, and occurrence depth information; the structural plane information includes structural plane type, aperture, presence or absence of filling materials, roughness, and occurrence, etc.; the structural plane filling material information includes water content, color, thickness, coherence, hardness, filling material type and source, etc.

[0028] Conduct on-site investigation of the engineering geological information of the shaft surrounding rock exposed during the shaft excavation, including shaft surrounding rock information and joint fracture occurrence information, etc.; the shaft surrounding rock information includes joints, bedding planes, interlayers, and fracture structures; the joint fracture occurrence information includes strike, dip, dip angle, fracture density, width, fracture filling, etc.

[0029] Through comprehensive evaluation of the engineering geological information of the exposed shaft surrounding rock and the engineering geological information of the core samples from the engineering geological exploration boreholes, ensure the accuracy of the engineering geological information of the ultra-deep shaft excavation area.

[0030] In this embodiment, the lithology of the shaft surrounding rock is granite, and the RQD value is above 50% (RQD is the rock quality index, used to measure the integrity of the rock mass), and the integrity of the rock mass is relatively good; the horizontal principal stress in the deep part of the stratum reaches 70 Mpa, and the uniaxial compressive strength of the rock does not exceed 180 Mpa. The type of rock mass structural plane is tectonic structural plane, including faults, joints, etc. The structural plane is relatively smooth, wavy, dip angle ≥ 60°, and microfractures (0.1 mm).

[0031] Step S12: According to the engineering geological survey information, collect rock samples and conduct indoor rock mechanics experiments, and classify the quality grades of rock masses at different depths of the shaft respectively using the Barton rock mass quality index Q classification method, the rock mass geomechanics RMR classification method, and the geological strength index GSI classification method. Specifically: Use the Barton rock mass quality index Q classification method to classify the quality grades of rock masses at different depths of the shaft. The Q value is determined by the following formula: ; In the formula, RQD is the rock mass quality index; J n is the number of joint sets; J r is the joint roughness coefficient; J a is the joint alteration coefficient; J w is the joint water reduction coefficient; SRF is the stress reduction coefficient.

[0032] In this embodiment, calculations are performed using the Barton Rock Mass Quality Index Q classification method to classify the rock mass quality grades at nine locations of the deep horizontal surrounding rock of the ultra-deep shaft from -1150 m to -1967 m.

[0033] The Rock Mass Geomechanics RMR classification method is used to classify the rock mass quality at different depths of the shaft. The RMR classification consists of six index parameters: the rock block strength A 1 , the RQD value A 2 , the joint spacing A 3 , the joint condition A 4 , the groundwater A 5 , and the correction factor for the influence of joint direction on the project A 6 . The RMR value is determined by the following formula: RMR = A 1 + A 2 + A 3 + A 4 + A 5 + A 6 ; In this embodiment, calculations are performed using the Rock Mass Geomechanics RMR classification method to classify the rock mass quality grades at nine locations of the deep horizontal surrounding rock of the ultra-deep shaft from -1150 m to -1967 m.

[0034] The Geological Strength Index GSI classification method is used to classify the rock mass quality at different depths of the shaft. The GSI classification can be used for the stability analysis of engineering-disturbed rock masses. The GSI modifies the Hoek-Brown rock mass failure strength criterion, reflects the weakening degree of various geological conditions on the rock mass strength, and is used to describe the characteristics of the rock mass. Its value ranges from 0 to 100.

[0035] In this embodiment, the Geological Strength Index GSI classification is obtained from Table 1.

[0036] Table 1 is the GSI classification chart

[0037] Based on the above three different types of rock mass quality classification methods, the rock mass quality grades of the deep horizontal surrounding rock at different depths of the ultra-deep shaft are obtained, as shown in Table 2: Table 2 Rock Mass Quality Classification Results of the Deep Horizontal Surrounding Rock at Different Depths of the Ultra-Deep Shaft

[0038] Step S13, according to the engineering geological information, comprehensive analysis is performed using the brittleness coefficient method, Barton method, and stress-strength method to obtain the evaluation result of the rockburst proneness of the surrounding rock of the ultra-deep shaft. Specifically: The engineering geological information includes the in-situ stress distribution of the ultra-deep shaft, the stress distribution of the shaft wall rock, and the test results of the rock physical and mechanical parameters.

[0039] Based on the in-situ stress distribution of the ultra-deep shaft, the stress distribution of the shaft wall rock, and the test results of the rock physical and mechanical parameters, comprehensive analysis is carried out using the brittleness coefficient method, Barton method, and stress-strength method to obtain the rockburst proneness grades of the surrounding rock at different depths of the ultra-deep shaft as shown in Table 3.

[0040] Table 3 Rockburst proneness grades of the shaft wall rock at different depths

[0041] Step S2: Divide the shaft cyclic excavation section according to the engineering geological information and determine the shaft rock drilling and blasting parameters; determine the stepped excavation construction method according to the engineering geological information and the rockburst proneness grade. Specifically, it includes: Step S21: Divide the ultra-deep shaft into N cyclic excavation sections according to the engineering geological information, where N is a positive integer. Specifically, divide the ultra-deep shaft into N cyclic excavation sections according to the designed depth of the ultra-deep shaft and the construction depth per cycle, where N is a positive integer.

[0042] In this embodiment, a complete set of technologies such as short-section tunneling and lining, and the supporting umbrella drill, large-scale rock grab, and integral moving metal formwork are used for regular cyclic parallel operation of tunneling and lining.

[0043] Two YSJZ4.8 hydraulic umbrella drills are used for rock drilling, and the blasting materials are 2# rock emulsion explosive and half-second delay detonator. According to the short-section tunneling and lining construction technology for domestic shaft construction, the cyclic footage is divided into 4m, and a 4.5m high integral downward metal formwork is used for lining to achieve regular cyclic operation.

[0044] Step S22: Divide the cross-section of each cyclic excavation section of the shaft into two steps; the excavation footage between two adjacent in-shaft steps in each cyclic excavation section is one tunneling and lining section height; where the tunneling and lining section height is 2m to 4m. Specifically: First, excavate 1 in-shaft step to form the first cyclic excavation section. When excavating the second to the Nth cyclic excavation sections, excavate 2 adjacent in-shaft steps simultaneously, including the upper step 1 and the lower step 2.

[0045] The excavation footage between two adjacent in-shaft steps in each cyclic excavation section is one tunneling and lining section height, and the construction method of each cyclic excavation section is the same.

[0046] Step S23: According to the engineering geological information, smooth surface, smooth bottom, weak shock and weak impact shallow-hole blasting techniques are adopted to determine the shaft drilling and blasting parameters. The shaft drilling and blasting parameters include explosive consumption, cartridge diameter and blasthole diameter, blasthole depth, number of blastholes, and blasthole layout, etc.

[0047] The explosive consumption is an important parameter to measure the shaft drilling and blasting effect. Therefore, the explosive consumption Q 炸药 is calculated by the formula: Q 炸药 =qSLη; In the formula, q is the unit explosive consumption, kg / m 3 ; S is the cross-sectional area of the shaft excavation, m 2 ; L is the average blasthole depth, m; η is the blasthole utilization rate.

[0048] The number of blastholes depends on the rock properties, explosive performance, shaft cross-sectional size, cartridge diameter, etc. After the total amount of explosive required for a single blast is determined, the number of blastholes is calculated according to the following formula: ; Substituting the explosive consumption calculation formula into the number of blastholes calculation formula, we get: ; In the formula, Q 炸药 is the explosive consumption; N is the number of blastholes, pieces; a is the charging coefficient (a = 0.5 - 0.7); p is the mass of each cartridge, kg; m is the length of each cartridge, mm.

[0049] The optimal cartridge diameter is based on obtaining a better blasting effect and not increasing the total drilling time as the measurement standard. According to practical experience, when using a cartridge with a diameter of 45mm instead of a cartridge with a diameter of 32mm, the number of blastholes can be reduced by 30% - 50%, the unit explosive consumption can be reduced by 20% - 25%, and the broken rock fragments are small, improving the mucking productivity.

[0050] In this embodiment, considering the characteristics of the comprehensive shaft excavation, the cartridge diameter of the cut holes 3 and the auxiliary holes 4 is 45mm, and the corresponding blasthole diameter is 48mm - 52mm. This can not only reduce the number of blastholes but also improve the blasting efficiency, and is also convenient for smooth blasting to ensure the shaft specifications.

[0051] The optimal blasthole depth should reduce the time and labor consumption per meter of the shaft and improve the equipment operation efficiency. When using a hydraulic jumbo drill and a large-scale mucker, the depth of the cut holes 3 is 4.7m, and the depth of other holes is 4.5m.

[0052] In the ultra-deep shaft blasting construction, the blasthole layout methods include: Determine the form and quantity of the cut holes 3, and arrange the cut holes 3. Specifically: Adopt the short-hole blasting technology to simultaneously excavate the adjacent two inner bench steps of the shaft, and select the vertical cut method for blasting to form the shaft. The calculation of the spacing of the cut holes 3 is based on the theory of rock cut expansion. The spacing between the cut holes 3 and the empty holes is determined by the following formula: ; In the formula, a is the hole spacing between the empty hole and the charged hole; D is the diameter of the empty hole; d is the diameter of the charged hole; K is the coefficient of rock expansion.

[0053] Determine the ring diameter of the cut holes 3 according to the rock hardness coefficient, and then calculate the quantity of the cut holes 3 in combination with the hole spacing a.

[0054] Determine the quantity of the perimeter holes 5, and arrange the perimeter holes 5. Specifically: Determine the ring diameter of the perimeter holes 5 according to the distance between the perimeter holes 5 and the shaft wall; then determine the quantity of the perimeter holes 5 according to the ring diameter and the hole spacing, and arrange the perimeter holes 5.

[0055] The perimeter holes 5 are generally arranged at a distance of 100 mm to 200 mm from the shaft wall, the hole spacing is 500 mm to 700 mm, and the minimum burden is about 700 mm. If smooth blasting is adopted, the hole density coefficient a = E / W = 0.8 to 1.0 must be considered. Where E is the hole spacing of the perimeter holes 5, and W is the minimum burden of the smooth blasting layer.

[0056] Determine the number of rings and quantity of the auxiliary holes 4, and arrange the auxiliary holes 4. Specifically: Determine the number of rings of the auxiliary holes 4 according to the rock hardness coefficient and the spacing between the cut holes 3 and the perimeter holes 5; generally control the ring spacing of each ring to be 600 mm to 1000 mm, taking the smaller value for hard rock and the larger value for soft rock, and the hole spacing is about 800 mm to 1000 mm.

[0057] Compile the blast hole layout based on the above calculations Figure 2 and Figure 3 ; The rock drilling and blasting parameters of the ultra-deep shaft are shown in Table 4.

[0058] Table 4 Rock Drilling and Blasting Parameter Table of the Shaft

[0059] Step S3: Carry out the energy release support design for the ultra-deep shaft according to the engineering geological information and the rockburst proneness level, and determine the support method and support parameters. Specifically include: Step S31: Preliminarily determine the composition of the support system according to the different rockburst grades of the surrounding rock of the ultra-deep shaft and the action mechanism of the support system. Specifically: In the case of mild rockburst grade, the support system mainly plays the roles of protection and surface restraint. Through methods such as rock bolts and shotcrete, enhance the integrity of the rock surface, prevent small pieces of rock from peeling off, and maintain the initial stability of the rock mass.

[0060] When it comes to the medium rockburst level, the support system not only needs to prevent rock spalling but also resist the impact of greater energy. Through methods such as energy-releasing support and cable bolts, it extends into the rock mass to provide stronger anchoring force, absorb and disperse the energy released by rockburst, and reduce the deformation and damage of the rock mass.

[0061] At the strong rockburst level, the support system faces great challenges. In addition to adopting the above measures, it is necessary to further optimize the parameters and layout of energy-releasing support and increase the density and length of bolt anchors, etc.; so as to more effectively resist the impact of rockburst and ensure the stability of underground engineering and the safety of personnel and equipment.

[0062] The rockburst mechanism is usually divided into four types: rock mass dilatancy without rock block ejection, rock block ejection caused by dilatancy, rock block ejection caused by far-field vibration, and rock collapse. The action mechanisms of the support system under different rockburst mechanisms and rockburst levels are shown in Table 5.

[0063] Table 5 Action mechanism table of support system under different rockburst mechanisms and different rockburst levels

[0064] Step S32, according to different rockburst mechanisms and rockburst levels, calculate three support indexes of the support system: the load safety factor, the displacement safety factor, and the energy safety factor. Specifically: The energy-releasing support design structure of the shaft under the dynamic impact of rockburst needs to resist the action of reciprocating dynamic loads, based on the swelling of the shaft surrounding rock caused by the violent deformation and damage of the rock mass under the action of dynamic loads. The traditional support design method mainly evaluates the safety factor of support design through the ratio of support capacity to support requirements; the shaft support design of high rockburst-prone rock mass should also meet the safety factor of traditional support design. In addition, the safety factor of the support design for high rockburst-prone rock mass should also meet the static support load, the displacement generated by the action of dynamic loads, and the amount of energy release, etc. Therefore, in the energy-releasing support design of high rockburst-prone rock mass, it is necessary to evaluate the three support indexes of load, displacement, and energy one by one. The specific process is as follows: Load index, usually the load index includes two types: dynamic load and static load. Under dynamic load, the dynamic load acceleration will increase the load and displacement requirements, requiring the flexible support system to release part of the kinetic energy until the static load support requirement is reduced to below the ultimate bearing capacity of the energy-releasing support system. Therefore, the load safety factor is calculated according to the following formula: ; Displacement index, when the shaft is subjected to the action of excavation disturbance stress and causes tangential failure, and the broken shaft surrounding rock produces swelling deformation, the support system is used to control the radial deformation of the shaft. Therefore, the designed support system must allow the support system to generate a large displacement, requiring the maximum deformation amount generated by the support system to be greater than the maximum deformation amount of the surrounding rock. Therefore, the displacement safety factor is calculated according to the following formula: ; Energy index. When rockburst occurs in the shaft and rock blocks are ejected from the surface of the shaft surrounding rock, they have relatively large kinetic energy, which causes the collapse of the shaft surrounding rock. The energy release support requires controlling the kinetic energy impact caused by the change of potential rockburst dynamic load. Therefore, when designing the support system, it is required that the maximum energy release capacity of the support system is greater than that of the surrounding rock. Therefore, the energy safety factor is calculated according to the following formula: .

[0065] Based on the above calculation formula, according to different rockburst mechanisms and rockburst grades, calculate the three support indexes of the load safety factor, displacement safety system and energy safety factor of the support system, as shown in Table 6.

[0066] Table 6 Load, displacement and energy safety factors of the support system corresponding to different rockburst mechanisms and rockburst grades

[0067] Step S33, determine the composition of the final support system according to the rockburst mechanism, rockburst grade and support indexes, and calculate the support system parameters. Specifically: Determine the support system: A standard support system composed of bolts and wire mesh usually has an energy release of less than 5 KJ / m 2 . By adding shotcrete to the standard support system, its energy release can be increased by more than one time. However, due to the limited ability of the standard bolt system to withstand large displacements, only by adding energy release bolts can the energy release of the support system be increased to 10 KJ / m 2 ~15 KJ / m 2 or more, and the use of energy release bolts doubles the energy release of the support system again.

[0068] Integrating the support system with the currently available, most effective and complementary support structures can release 30 KJ / m 2 ~40 KJ / m 2 of energy. The support systems corresponding to different rockburst mechanisms and different rockburst grades are shown in Table 7.

[0069] Table 7 Support systems corresponding to different rockburst mechanisms and rockburst grades

[0070] Calculating the support system parameters includes: Obtain the energy on the surface of the shaft surrounding rock during rockburst and the energy released per unit area of the bolts; calculate the spacing between bolts according to the energy released per unit area of the bolts being greater than the energy on the surface of the shaft surrounding rock during rockburst; Obtain the shaft span and the RMR value; calculate the bolt length according to the shaft span and the RMR value.

[0071] Since rockburst is a dynamic failure and its failure process is accompanied by energy accumulation and release, a energy-releasing support system is designed from the perspective of energy balance. The specific process is as follows: According to the kinetic energy E generated during the rockburst process e and the potential energy E during the rockburst process P , the energy E on the surface of the shaft surrounding rock during rockburst is calculated. C , and the energy E on the surface of the shaft surrounding rock during rockburst is calculated according to the following formula: C : E C= E e+ E p ; For the convenience of calculation, the rock bolts are analyzed using the energy per unit area; according to the spacing and row spacing of the rock bolt support per unit area and the maximum energy e that a single rock bolt can release, the energy E released per unit area of the rock bolts is calculated. The energy E released per unit area of the rock bolts is calculated according to the following formula: ; Among them, the spacing and row spacing of the rock bolt support per unit area =a×b (m×m), where a is the spacing and b is the row spacing; To ensure the stability of the shaft surrounding rock, in actual working conditions, it should be ensured that the energy E released by the support system is greater than the energy E on the surface of the shaft surrounding rock during rockburst C , and the lateral pressure coefficient is considered to be increased; therefore, the actual spacing and row spacing of the rock bolt support is: ; In the formula, λ is the lateral pressure coefficient; According to the excavation span and RMR value, the length of the rock bolt is calculated; the length of the rock bolt is calculated according to the following formula: ; In the formula, L is the excavation span, and the excavation span is equal to the shaft diameter, m; L b is the length of the rock bolt, m.

[0072] In this embodiment, the energy-releasing support system is composed of energy-releasing rock bolts, metal meshes, mesh clips and shotcrete; among them, the energy-releasing rock bolts are J energy-releasing rock bolts, and the length L b of the energy-releasing rock bolts is 3m, and the spacing and row spacing s 2 is 1m×1m.

[0073] Step S4, loading and mucking. Specifically, it includes: Step S41, using a rock grabber in cooperation with an excavator to first carry out sectional loading and mucking leveling on the shaft working face, and then carry out bottom cleaning.

[0074] Step S42: When the slag discharge height at the shaft working face reaches the excavation and lining section height, level the slag surface around the shaft wall.

[0075] Specifically: Use a central rotary rock grab in cooperation with an excavator to first carry out sectional rock loading and mucking leveling on the shaft working face, and then carry out bottom cleaning to create conditions for rock drilling and blasting work to improve the blasting effect. When the slag discharge height at the shaft working face reaches the excavation and lining section height, level the slag surface around the shaft wall to meet the requirements of lining construction.

[0076] Step S5: Determine the permanent support timing of the concrete lining through the stability chart of RMR rock mass geomechanics classification or by obtaining the evolution process of the surrounding rock pressure of the deep vertical shaft excavation shaft through on-site ground pressure monitoring means.

[0077] According to the permanent support timing of the concrete lining, carry out temporary support of bolt-net-shotcrete and permanent support of concrete lining for the ultra-deep vertical shaft. Specifically include: Step S51: Select the maximum self-stable height of the shaft surrounding rock through the stability chart of RMR rock mass geomechanics classification or obtain the evolution process of the surrounding rock pressure of the deep vertical shaft excavation shaft through on-site ground pressure monitoring means to select the appropriate permanent support height of the shaft, and then determine the permanent support timing of the concrete lining.

[0078] Utilize the pressure relief effect of plastic failure of the shaft surrounding rock under high stress action to increase the distance between the cross-section of the shaft lining and the shaft working face, and sequentially support to release the high stress concentrated on the surface of the shaft surrounding rock, so that the concrete shaft wall is in a state of slow pressure bearing or pressure-free bearing.

[0079] The safety height between the temporary support driving face of the shaft and the shaft wall is an important parameter in the process of regulating the surrounding rock pressure of the deep vertical shaft; in this embodiment, based on the stability chart of RMR rock mass geomechanics classification, the maximum self-stable height of the shaft surrounding rock is obtained as 12m, that is, the permanent support timing of the concrete lining is determined. Further explanation is that when multiple excavation and lining section heights reach the maximum self-stable height of 12m of the shaft surrounding rock, carry out permanent support of concrete lining on the shaft wall.

[0080] Step S52: According to the permanent support timing of the concrete lining, carry out temporary support of bolt-net-shotcrete and permanent support of concrete lining for the ultra-deep vertical shaft; specifically include: When the shaft excavation reaches the first excavation and lining section height, carry out primary support, spray concrete to seal the shaft surrounding rock, install energy-releasing bolts and metal meshes. At this time, the temporary support construction of one excavation and lining section height is completed, and then cycle to excavate the next excavation and lining section height; when multiple excavation and lining section heights reach the maximum self-stable height of the shaft surrounding rock, support the formwork and pour concrete to carry out permanent support of concrete lining for the shaft surrounding rock. To ensure the safety of personnel and equipment during construction, and at the same time fully mobilize the self-stable ability of the shaft surrounding rock and adjust the internal pressure of the shaft surrounding rock.

[0081] This application is applicable to ultra-deep vertical shafts with rock burst disasters at depths of 1200 m or more. In order to mitigate the ground pressure disasters caused by excavation disturbance stress, bench blasting and energy-releasing support technologies are used to regulate the concentrated stress of the shaft surrounding rock, release the energy accumulated in the surrounding rock, and enable the stress of the shaft surrounding rock to quickly return to a balanced state, ensuring the safety of construction personnel and the concrete shaft wall. First, a transparent analysis of the ultra-deep vertical shaft formation is carried out. The rock mass quality grade is divided and the rock burst tendency of the shaft surrounding rock is judged through the rock cores of the engineering exploration holes and engineering geological surveys. Secondly, the shaft is constructed by the bench blasting step-by-step excavation method to reduce the vibration impact of blasting on the shaft and its nearby buildings and increase the free surface in the next blasting stage. By adopting an energy-releasing support structure, the stress distribution around the shaft is adjusted, stress concentration is avoided, the deformation of the shaft surrounding rock is reduced, and the stability of the shaft is further enhanced in cooperation with bench blasting.

[0082] It is easy for those skilled in the art to understand that, on the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0083] The above are only the preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this application shall be included within the protection scope of this application. The above is only the preferred implementation manner of this application. It should be noted that for those of ordinary skill in the art in this technical field, several improvements and modifications can be made without departing from the technical principle of this application, and these improvements and modifications should also be regarded as within the protection scope of this application.

Claims

1. A method for supporting and excavating ultra-deep shaft steps in metal mines by blasting energy release, characterized in that: include: Acquire engineering geological information of the ultra-deep shaft excavation area, classify the quality grade of the surrounding rock mass at different depths of the shaft according to the engineering geological information, and evaluate the rock burst tendency grade of the surrounding rock at different depths of the shaft; Dividing the shaft excavation cycle sections and determining the shaft drilling and blasting parameters according to the engineering geological information; Determining a stepped excavation construction method according to the engineering geological information and the rockburst tendency level; Perform energy release support design for the ultra-deep shaft according to the engineering geological information and the rockburst tendency grade, and determine the support method and support parameters; Loading rock and removing slag; Obtain the opportunity for permanent support of concrete lining, and carry out temporary support of anchor mesh spraying and permanent support of concrete lining for ultra-deep shafts.

2. The method for supporting and excavating ultra-deep shaft steps in a metal mine by blasting and releasing energy according to claim 1 is characterized in that: The steps of obtaining engineering geological information of the ultra-deep shaft excavation area, classifying the quality grades of the surrounding rock masses at different depths of the shaft according to the engineering geological information, and evaluating the rock burst tendency grades of the surrounding rocks at different depths of the shaft, include: Compile the engineering geological information of the exploration borehole cores; obtain the engineering geological information of the shaft surrounding rock revealed during the shaft excavation process; evaluate the engineering geological information of the ultra-deep shaft excavation area based on the engineering geological information of the shaft surrounding rock revealed and the engineering geological information of the exploration borehole cores; According to the engineering geological information, the rock mass quality at different depths of the wellbore is graded using the Barton rock mass quality index Q classification method, the rock mass geomechanics RMR classification method and the geological strength index GSI classification method; According to the engineering geological information, the brittleness coefficient method, the Patton method and the stress-strength method were used for comprehensive analysis to obtain the rockburst tendency evaluation results of the surrounding rock of the ultra-deep vertical shaft.

3. The method for supporting and excavating ultra-deep shaft steps in a metal mine by blasting and releasing energy according to claim 1 is characterized in that: The steps of dividing the shaft cyclic excavation sections and determining the shaft rock drilling and blasting parameters according to the engineering geological information include: According to the engineering geological information, the ultra-deep vertical shaft is divided into N cyclic excavation sections, where N is a positive integer; According to the engineering geological information, the smooth surface, smooth bottom, weak earthquake and weak impact shallow hole blasting technology is adopted to determine the wellbore rock drilling blasting parameters.

4. A method for supporting and excavating ultra-deep shaft steps in a metal mine by blasting and releasing energy according to claim 3, characterized in that: The smooth surface, smooth bottom, weak vibration and weak impact shallow hole blasting technology is used to determine the wellbore rock drilling and blasting parameters, wherein the wellbore rock drilling and blasting parameters include explosive consumption, charge roll diameter and blast hole diameter, blast hole depth, blast hole number and blast hole arrangement.

5. A method for supporting and excavating ultra-deep shaft steps in a metal mine by blasting and releasing energy according to claim 4, characterized in that: The explosive consumption is an important parameter to measure the effect of wellbore rock drilling and blasting. Therefore, the explosive consumption Q 炸药 The calculation formula is: Q 炸药 =qSLη; In the formula, q is the unit explosive consumption; S is the cross-sectional area of ​​the shaft excavation; L is the average depth of the blasthole; η is the blasthole utilization rate; The calculation formula for the number of blastholes is: ； Substituting the explosive consumption calculation formula into the blasthole quantity calculation formula, we get: ； In the formula, Q 炸药 is the consumption of explosives; N is the number of blast holes; a is the charging coefficient (a=0.5~0.7); p is the mass of each cord; m is the length of each cord.

6. The method for supporting and excavating ultra-deep shaft steps in a metal mine by blasting and releasing energy according to claim 4, characterized in that: In the ultra-deep shaft blasting construction, the blasthole arrangement methods include: Determine the form and quantity of the slot holes (3), and arrange the slot holes (3); Determine the number of peripheral holes (5) and arrange the peripheral holes (5); The number and quantity of the auxiliary holes (4) are determined, and the auxiliary holes (4) are arranged.

7. The method for supporting and excavating ultra-deep shaft steps in a metal mine by blasting energy release according to claim 1, characterized in that: The steps of designing energy release support for the ultra-deep shaft according to the engineering geological information and the rockburst tendency grade, and determining the support method and support parameters include: According to the different rockburst grades of the surrounding rocks of the ultra-deep shaft and the action mechanism of the support system, the composition of the support system is preliminarily determined; According to different rockburst mechanisms and rockburst levels, three support indicators of the support system, namely load safety factor, displacement safety factor and energy safety factor, are calculated; According to the rockburst mechanism, rockburst grade and support index, the final support system composition is determined and the support system parameters are calculated.

8. The method for supporting and excavating ultra-deep shaft steps in a metal mine by blasting energy release according to claim 7, characterized in that: According to different rockburst mechanisms and rockburst levels, the steps for calculating the three support indicators of the support system, namely, the load safety factor, displacement safety factor and energy safety factor, include: The calculation formula for the load safety factor is: FS 载荷 =Supporting force of support system / surrounding rock pressure; The calculation formula of displacement safety factor is: ； The calculation formula of energy safety factor is: 。 9. The method for supporting and excavating ultra-deep shaft steps in a metal mine by blasting and releasing energy according to claim 7, characterized in that: The step of calculating the support system parameters comprises: Obtain the surface energy of the surrounding rock of the wellbore when rock burst occurs, and obtain the energy released per unit area of ​​the anchor rod; calculate the spacing of the anchor rod support based on the energy released per unit area of ​​the anchor rod being greater than the surface energy of the surrounding rock of the wellbore when rock burst occurs; Obtain the wellbore span and RMR value; calculate the anchor length based on the wellbore span and RMR value.

10. The method for supporting and excavating ultra-deep shaft steps in a metal mine by blasting and releasing energy according to claim 1, characterized in that: The steps of obtaining the opportunity for permanent support of concrete lining and performing temporary support of anchor mesh spraying and permanent support of concrete lining on the ultra-deep shaft include: Determine the timing of permanent support for concrete lining by using stability diagrams of RMR rock mass geomechanical classification or by obtaining the evolution of surrounding rock pressure during deep shaft excavation through on-site ground pressure monitoring; According to the timing of permanent support of concrete lining, temporary support of anchor mesh spraying and permanent support of concrete lining are carried out for the ultra-deep shaft.

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