Construction method of large-diameter vertical shaft of special long tunnel

Abstract

This invention discloses a method for constructing large-diameter vertical shafts in extra-long tunnels, relating to the field of tunnel construction technology. The method involves constructing pilot holes with a first preset diameter along the downward direction of the shaft in a pre-defined construction area located on the surface of the shaft of the extra-long tunnel. This yields at least two target pilot holes spaced apart within the construction boundary of the shaft. At the bottom of each pilot hole, a second preset diameter is used to enlarge the hole upwards from the bottom of each target pilot hole to obtain the current hole. The excavated soil from the drilling falls and fills the cavities, thus achieving the function of enlarging the target pilot holes. After the enlargement is completed and the current hole is formed at the bottom, directional controlled blasting is used to cause the surrounding rock corresponding to the bottom area of ​​the hole to fall in and fill the cavities. This reduces the difficulty and volume of excavated soil transportation, avoids the impact on drainage, ventilation, and excavation caused by the increased shaft depth, improves construction safety, and ensures construction efficiency.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a method for constructing large-diameter vertical shafts in extra-long tunnels. Background Technology

[0002] Long tunnels in mountainous areas and complex geological conditions are becoming increasingly common, and among these long tunnels, the use of vertical shaft ventilation is also on the rise. Under increasingly stringent operational requirements and the pressure of emergency rescue, the diameter of vertical shafts is gradually increasing to meet ventilation needs, which in turn increases construction costs and raises safety concerns.

[0003] In existing technologies, the construction of large-diameter vertical shafts typically involves excavating the entire shaft from the top opening (the area above the top of the shaft) downwards. While this method can create large-diameter shafts, as the shaft depth increases, drainage, ventilation, and slag removal become problematic, posing safety hazards and impacting construction efficiency. Summary of the Invention

[0004] The main objective of this invention is to propose a construction method for large-diameter vertical shafts in extra-long tunnels. This method aims to solve the technical problem in the prior art where, when using full-face excavation for vertical shaft construction, the increasing depth of the shaft affects drainage, ventilation, and muck removal, posing construction safety hazards and also impacting construction efficiency.

[0005] To achieve the above objectives, in a first aspect, the present invention proposes a method for constructing a large-diameter vertical shaft for an extra-long tunnel, wherein a karst cavity is formed within the building boundary of the extra-long tunnel, and the vertical shaft is configured corresponding to the karst cavity; the method for constructing a large-diameter vertical shaft for an extra-long tunnel includes the following steps: In the pre-designated construction area, pilot holes are constructed along the direction extending downward from the shaft according to the first pre-designated diameter to obtain at least two target pilot holes spaced apart within the building boundary line of the shaft; wherein, the pre-designated construction area is located on the ground surface of the area where the shaft of the extra-long tunnel is located, and the bottom of the pilot holes extends and penetrates into the tunnel; When drilling reaches the bottom of each of the pilot holes, the current hole is obtained by enlarging the hole from the bottom of each of the target pilot holes upwards according to the second preset hole diameter, and the slag formed by drilling falls and fills the cavity; wherein, the size of the second preset hole diameter is larger than the size of the first preset hole diameter; After the borehole enlargement is completed and the bottom of the current borehole is formed, directional controlled blasting is used to cause the surrounding rock corresponding to the bottom of the borehole to fall in and fill the cavity. After filling the cavity to a preset elevation, excavation work is carried out in the preset construction area until the shaft is formed.

[0006] In one embodiment, before the step of using directional controlled blasting to cause the surrounding rock corresponding to the bottom area of ​​the hole to fall into and fill the cavity at the bottom position of the hole after the hole enlargement construction is completed and the current hole is formed, the method further includes: Based on the preset data of the shaft, determine the current explosive equivalent required to excavate to the preset diameter of the shaft using controlled blasting in the current hole; wherein, the preset data includes the preset diameter of the shaft, the distance between the current hole and the preset shaft wall, the surrounding rock data at the location of the shaft, and the geological data at the location of the shaft; The step of using directional controlled blasting to cause the surrounding rock corresponding to the bottom area of ​​the hole to fall into and fill the cavity after the hole enlargement construction is completed and the current hole is formed includes: After the borehole enlargement is completed and the bottom of the current borehole is formed, the surrounding rock corresponding to the bottom of the borehole is caused to fall into and fill the cavity by directional controlled blasting according to the current explosive equivalent.

[0007] In one embodiment, after determining the current explosive equivalent required to excavate to a preset diameter of the shaft using controlled blasting based on preset data of the shaft, the method further includes: Based on the preset data of the shaft, the blasting impact height of the current explosive equivalent along the extension direction of the current hole is obtained; The number of blasts required for the vertical shaft is determined based on the height of the blasting impact.

[0008] In one embodiment, before the step of using directional controlled blasting to cause the surrounding rock corresponding to the bottom area of ​​the hole to fall into and fill the cavity at the bottom position of the hole after the hole enlargement construction is completed and the current hole is formed, the method further includes: The number of blasts is sequentially numbered according to the vertical shaft's extension direction from bottom to top; The step of using directional controlled blasting to cause the surrounding rock corresponding to the bottom area of ​​the hole to fall into and fill the cavity after the hole enlargement construction is completed and the current hole is formed includes: After the borehole enlargement is completed and the bottom of the current borehole is formed, directional controlled blasting is used to cause the surrounding rock corresponding to the bottom area of ​​the borehole to fall in and fill the cavity.

[0009] In one embodiment, the step of using directional controlled blasting at the bottom of the borehole after the borehole enlargement construction and the formation of the current borehole to cause the surrounding rock corresponding to the bottom area of ​​the borehole to fall in and fill the cavity includes: After the hole enlargement construction is completed and the current hole is formed, the area corresponding to the number at the bottom of the current hole is taken as the current blasting area. In the current blasting area, explosives are loaded according to the current explosive equivalent and directional controlled blasting is used to cause the surrounding rock corresponding to the bottom area of ​​the hole to fall in and fill the cavity, forming a new hole; Support work is carried out on the walls of the new holes; The top of the new hole is taken as the bottom position of the current hole, and the step of taking the area corresponding to the number of the bottom position of the current hole as the current blasting area is repeated until the support operation of the hole wall of the new hole is performed to form a new hole, until the surrounding rock and soil formed by the blasting fill the cavity to the preset elevation.

[0010] In one embodiment, the steps of taking the top of the new hole as the bottom position of the current hole, and repeatedly performing the step of taking the area corresponding to the number of the bottom position of the current hole as the current blasting area until the support operation on the hole wall of the new hole is performed to form a new hole, until the surrounding rock and soil formed by the blasting fill the cavity to the preset elevation, further include: Based on the pre-defined survey data of the cavity, the required volume of surrounding rock and soil to fill the cavity to the pre-defined elevation is obtained; Based on the volume of surrounding rock debris, the blasting height of the current hole is obtained; The number of blasts is determined based on the blasting height. The step of taking the top of the new hole as the bottom position of the current hole, and repeatedly executing the step of taking the area corresponding to the number of the bottom position of the current hole as the current blasting area, to supporting the hole wall of the new hole to form a new hole, until the surrounding rock and soil formed by the blasting fill the cavity to the preset elevation, includes: The top of the new hole is taken as the bottom position of the current hole, and the step of taking the area corresponding to the number of the bottom position of the current hole as the current blasting area to support the hole wall of the new hole is repeated until the blasting operation of the specified number of blasts is completed, so that the surrounding rock and soil formed by the blasting fill the cavity to the preset elevation.

[0011] In one embodiment, the step of supporting the wall of the new hole includes: Initial and secondary support work is carried out on the walls of the new holes.

[0012] In one embodiment, the step of excavating in the preset construction area after filling the cavity to a preset elevation until the shaft is formed includes: After filling the cavity to the preset elevation, construct the wellhead structure of the vertical shaft in the preset construction area; Excavation work is carried out on the inner side of the wellhead structure to create the vertical shaft.

[0013] In one embodiment, the step of excavating inside the wellhead structure to create the vertical shaft includes: The target height is excavated downwards from the inside of the wellhead structure to form the current foundation pit; Support work is carried out on the current foundation pit to obtain the first foundation pit; When the walls of the first pit reach a preset strength, the steps of excavating downward to the target height inside the wellhead structure to form the current pit and then supporting the current pit are repeated at the bottom of the first pit until the vertical shaft is formed.

[0014] In one embodiment, the step of constructing the wellhead structure of the vertical shaft in the preset construction area after filling the cavity to the preset elevation includes: When the cavity is filled to the preset elevation, the shaft ring structure and the lock ring structure are constructed sequentially in the preset construction area to obtain the shaft opening structure; wherein, the lock ring structure is located inside the shaft ring structure.

[0015] In use, the technical solution of this invention involves drilling pilot holes at a predetermined construction area on the surface of the shaft of an extra-long tunnel, extending downwards along the shaft according to a first predetermined diameter. This yields at least two target pilot holes spaced apart within the shaft's building boundary line, thereby creating an underground construction face on the surface. Then, when drilling reaches the bottom of each pilot hole, the borehole is enlarged upwards from the bottom of each target pilot hole according to a second predetermined diameter to obtain the current borehole. The excavated soil from the drilling falls and fills the cavity, thus achieving the function of enlarging the target pilot holes. After completing the enlargement and forming the current borehole... At the bottom position, a directional controlled blasting method is used to cause the surrounding rock corresponding to the bottom area of ​​the borehole to fall in and fill the cavity. This invention allows the surrounding rock generated during the blasting of the shaft to be directly used for cavity filling, reducing the transportation of excavated soil. At the same time, since the surrounding rock and excavated soil generated by blasting are directly used for cavity filling, the construction efficiency is improved. After the cavity is filled to the preset elevation, excavation work is carried out in the preset construction area until the shaft is formed. This invention reduces the difficulty and volume of excavated soil transportation, and there is no situation where drainage, ventilation and slag removal are affected by the increase in shaft depth, thus improving construction safety and ensuring construction efficiency. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 A flowchart illustrating an embodiment of the construction method for large-diameter vertical shafts in extra-long tunnels provided by the present invention; Figure 2 Flowcharts of some specific embodiments of the present invention; Figure 3 for Figure 2 The flowchart of step S300 in the example is shown; Figure 4 for Figure 3 The flowchart of step S310 in the example is shown below; Figure 5 for Figure 1 The flowchart of step S400 in the example is shown; Figure 6 for Figure 5 The flowchart for step S420 in the example is shown.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] This invention proposes a method for constructing large-diameter vertical shafts in extra-long tunnels.

[0023] Please see Figures 1 to 6 For ease of understanding, this method for constructing large-diameter vertical shafts in extra-long tunnels involves the formation of karst cavities within the tunnel's building boundary, with the vertical shafts corresponding to these cavities. The method includes the following steps: S100. In the preset construction area, guide holes are constructed along the direction extending downward from the shaft according to the first preset diameter to obtain at least two target guide holes spaced apart within the building boundary line of the shaft; wherein, the preset construction area is located on the ground surface of the area where the shaft of the extra-long tunnel is located, and the bottom of the guide holes extends and penetrates into the tunnel.

[0024] Specifically, the pre-set construction area is selected based on geological exploration data at a location on the ground directly above the shaft axis, and is precisely positioned and laid out using a total station. The first pre-set borehole diameter ranges from 150-300mm (preferred in this embodiment is 250mm), and a composite roller cone drilling rig is used for vertical directional drilling. During the construction of the pilot borehole, the deviation is monitored in real time, and the verticality error is controlled within 0.5‰ using a hydraulic correction system for the drill rod. The bottom of the target pilot borehole must penetrate at least 3m into the tunnel structure outline, forming a vertical channel through the karst cavity area. In particular, when constructing in karst landform areas, the spacing between the pilot boreholes is dynamically adjusted according to the degree of karst cavity development. A typical configuration is three pilot boreholes spaced 120° apart along the circumference of the shaft, forming a triangular control network.

[0025] S200. When drilling reaches the bottom of each of the pilot holes, the current hole is obtained by expanding the hole from the bottom of each of the target pilot holes upwards according to the second preset hole diameter, and the slag formed by drilling falls and fills the cavity; wherein, the size of the second preset hole diameter is larger than the size of the first preset hole diameter.

[0026] Once the drill bit reaches the bottom elevation of the pilot hole, the reverse circulation reaming tool is replaced. The second preset hole diameter is set to 1000-2000 mm (preferably 1600 mm in this embodiment), and a staged reverse pull reaming process is adopted. During the reaming process, the cutting rock chips are discharged along the annular gap between the drill rod and the hole wall through the air-lift reverse circulation system. At the same time, a cutting rock chip diversion device is set up so that 30%-40% of the cuttings fall freely into the cavity area of ​​the solution through the pilot hole.

[0027] S300. After completing the borehole enlargement construction and forming the bottom position of the current borehole, a directional controlled blasting method is used to cause the surrounding rock corresponding to the bottom area of ​​the borehole to fall in and fill the cavity.

[0028] A 3-5m rock column is reserved at the bottom of the borehole as the blasting free face, and a radial shaped charge structure is arranged. Blasting parameters are dynamically adjusted based on the rock mass integrity coefficient detected by sonic CT, with a typical charge amount of 0.6-0.8 kg / m³. The initiation network uses non-electric detonating cords for borehole-by-hole micro-delay initiation, with a delay accuracy controlled within 5ms. A three-dimensional vibration monitoring system ensures that the blasting vibration velocity does not exceed the threshold of 15cm / s. The particle size of the blasted debris is controlled by adjusting the charge spacing, requiring that more than 80% of the fragments be less than 300mm in diameter to ensure effective filling of the cavity voids during the fall. In particular, a buffer layer is set in the weak area of ​​the cavity top plate, and rapid-setting mortar is used to pre-grout and reinforce key fractures.

[0029] S400. After filling the cavity to a preset elevation, excavation work is carried out in the preset construction area until the shaft is formed.

[0030] Once the cavity filling density reaches 85% and settlement stabilizes, vertical shaft construction using the main shaft method is initiated. A layered excavation is carried out using an umbrella-shaped drill rig in conjunction with a large rock grabber, with each cycle advancing 1.2-1.5 meters. An advanced small-diameter grouting system is installed at the contact zone between the filling material and the original rock strata, maintaining the grouting pressure within the range of 2-3 MPa. Hydraulic sliding formwork is installed simultaneously during excavation, and concrete pouring is carried out continuously using the vertical duct method. Fiber optic sensors installed within the shaft wall monitor structural stress in real time; when abnormal strain is detected in the filling area, a radial compensation grouting procedure is immediately initiated.

[0031] In this embodiment, by constructing pilot holes in a predetermined construction area located on the surface of the shaft of the extra-long tunnel, and extending downwards along the shaft according to a first predetermined diameter, at least two target pilot holes are formed at intervals within the building boundary line of the shaft. This allows for the creation of an underground construction face on the surface. Then, when drilling reaches the bottom of each pilot hole, the borehole is enlarged upwards from the bottom of each target pilot hole according to a second predetermined diameter to obtain the current hole. The excavated soil from the drilling falls and fills the cavity, thus achieving the function of enlarging the target pilot holes. After completing the enlargement and forming the bottom of the current hole... By employing directional controlled blasting, the surrounding rock corresponding to the bottom area of ​​the borehole falls in and fills the cavity. This allows the invention to directly utilize the surrounding rock generated during the blasting of the shaft for cavity filling, reducing the transportation of excavated soil. Furthermore, the direct use of the blasted surrounding rock and excavated soil for cavity filling improves construction efficiency. After filling the cavity to the preset elevation, excavation work is carried out in the preset construction area until the shaft is formed. This invention further reduces the difficulty and volume of excavated soil transportation, and avoids the impact on drainage, ventilation, and slag removal caused by increased shaft depth, thus improving construction safety and ensuring construction efficiency.

[0032] In one embodiment, prior to step S300, the method further includes: S10. Based on the preset data of the shaft, determine the current explosive equivalent required to excavate to the preset diameter of the shaft using controlled blasting in the current hole; wherein, the preset data includes the preset diameter of the shaft, the distance between the current hole and the preset shaft wall, the surrounding rock data at the location of the shaft, and the geological data at the location of the shaft.

[0033] Specifically, the preset data includes a target well diameter of 7.8m, a current borehole-to-design wellbore distance of 1.5m, a Protodyakonov coefficient of f=4 for the surrounding rock, a rock mass wave velocity of 4200m / s, and a joint surface dip angle of 55°. The explosive equivalent is calculated using a modified Langevos formula: Where D is the designed well diameter, d is the current borehole diameter, S is the borehole spacing, and V_p is the longitudinal wave velocity. After inputting the parameters, the linear charge density is obtained as 1.8 kg / m, and the total charge is calculated to be 57.6 kg based on the blasting section height of 3.2 m. Simultaneously, the charge structure is optimized: Φ42 mm cartridges are used for interval loading, with a radial decoupling coefficient of 1.3 and an axial air gap length of 0.4 m to ensure that the blasting energy matches the rock mass impedance.

[0034] Step S300 includes: S310. After completing the hole enlargement construction and forming the bottom position of the current hole, the surrounding rock corresponding to the bottom area of ​​the hole falls into and fills the cavity according to the method of directional controlled blasting with the current explosive equivalent.

[0035] In another verification embodiment, 24 charging holes were arranged in a double-helix array at the bottom of the borehole, with the inner ring of 8 holes 2.1m from the center and the outer ring of 16 holes 3.8m from the center. Each borehole was charged in three sections, each containing 2.4kg of emulsion explosive, and detonated with a digital detonator using a 25ms differential delay. After detonation, a stress wave convergence zone was formed, causing tensile-shear composite fracturing of the dolomite within a 2.8m radius below the borehole bottom. The volume of the fractured rock fragments was calculated using a block size calculation model.

[0036] (K=0.045, Q is the charge per hole, R is the resistance line, σ_t is the tensile strength of the rock) The effective volume of the falling rock was 126 m³. After the falling rock mass was mixed with 650 m³ of gravel generated during the pilot hole stage, the cavity filling rate reached 93%. The elevation error of the top surface of the filling was ±12 cm after 3D point cloud scanning.

[0037] To better understand this invention, in an example embodiment, a railway tunnel shaft project is used. The shaft depth reaches 342m and needs to pass through three beaded karst cavities with a cumulative volume of 980m³. Geological data retrieved by the construction control unit shows that the surrounding rock is Permian limestone with an RQD value of 72% and a karst development coefficient of 0.38. Parametric modeling calculations yielded a charge weight of 2.1kg per linear meter. In actual construction, Φ45mm high-velocity explosives were used with a charge density of 1.6g / cm³, and detonation was conducted via in-hole detonating cord. Post-blast monitoring data indicates that: The vibration monitoring instrument recorded a maximum vibration velocity of 2.8 cm / s, which complies with the GB6722-2014 safety standard; the filler was tested by core drilling, and the average block diameter was 38 cm with a porosity of 18%. In the subsequent excavation stage, the ventilation efficiency is increased to 4.2 m³ / s, which is 55% higher than the traditional construction method. During the construction process, the temperature change of the hole wall is monitored in real time through the optical fiber temperature measurement system installed in the pilot hole. When the temperature gradient exceeds 0.8 °C / m, the emergency ventilation is automatically started. The mucking system adopts a grab basket with variable frequency control, and the lifting speed is dynamically adjusted between 1.2 - 1.8 m / s according to the amount of muck, ensuring that the mucking volume per hour is stable at 22 m³. After the filling body reaches the design strength, a ground penetrating radar is used to detect the quality of the cavity filling. When the reflection wave amplitude attenuation coefficient ≤ 0.15, it is judged as qualified.

[0038] Through the quantitative blasting parameter calculation model, the precise matching of energy release and rock mass fragmentation is achieved, and the overbreak is controlled within 5 cm. The combined action of the double - helix charge structure and the millisecond delay initiation technology forms a directional fracture zone, enabling more than 80% of the rock blocks to fall into the cavity along the predetermined trajectory. The application of the three - dimensional monitoring system ensures that the risks in the whole construction process are controllable.

[0039] In one embodiment, after step S10, it further includes: S20. Obtain the blasting influence height of the current explosive equivalent along the extension direction of the current hole according to the preset data of the shaft.

[0040] Specifically, the engineering control unit has a built - in rock mass mechanics parameter database, and retrieves the uniaxial compressive strength of the surrounding rock σ c = 85 MPa, the rock mass integrity coefficient Kv = 0.65, and the joint spacing J = 0.3 - 0.5 m from the preset data of the shaft. The blasting influence height H is calculated by the modified Hopkins formula:

[0041] where Q is the current explosive equivalent (kg / m³), and ρ is the rock mass density (taking 2.8 g / cm³). When Q = 42 kg / m³, H = 3.2 m is calculated. During implementation, a three - dimensional laser scanner is used to perform point cloud modeling on the current hole, and combined with the fracture development direction detected by the ground penetrating radar, the value of H is dynamically adjusted. When the rock mass wave velocity Vp > 4500 m / s, the H coefficient correction factor α takes 1.15 to ensure that the blasting fragmentation zone covers the roof rock layer of the cavity.

[0042] S30. Determine the blasting times of the shaft according to the blasting influence height.

[0043] The blasting times N is calculated by the formula where D is the designed depth of the shaft. When D = 280 m and H = 3.2 m, N = 88 times. During implementation, the layered cumulative method is used to control the blasting process: The first - cycle blasting depth is 5 m, and an acoustic monitoring array is installed. When the rock mass fragmentation degree β ≥ 85% is collected in real time, the next cycle is triggered; After every 10 blasts, the wellbore deviation is detected using a fiber optic gyroscope. When Δθ > 0.5° / 10m, a correction blasting layer is inserted. Two meters before the final blast, the system switches to pre-splitting blasting mode, reducing the charge density to 70% of the standard value to create a buffer zone. This method allows the determination of the specific number of blasts.

[0044] In one embodiment, prior to step S30, the method further includes: S500. The number of blasting operations is sequentially numbered according to the vertical shaft's extension direction from bottom to top. Specifically, the engineering control unit has a built-in blasting sequence generation module. Based on the designed shaft depth of 428m and the single blast's impact height of 3.5m, it generates a numbering sequence N001-N123. The numbering rule adopts a depth-reverse marking method: using the bottom elevation of -428m as a reference point, blasting segments are divided upwards every 3.5m, with each number corresponding to a specific elevation interval. During implementation, the hole depth is calibrated in real time using a laser rangefinder. When the actual hole depth deviates from the design value by more than ±0.3m, a dynamic adjustment program is triggered to recalculate the remaining blasting count and update the numbering. The numbering data is transmitted to the charging robotic arm control system via an industrial bus to ensure precise matching between each charging hole and the blasting number.

[0045] Step S310 includes: S311. After completing the borehole enlargement construction and forming the bottom position of the current borehole, use directional controlled blasting to cause the surrounding rock corresponding to the bottom area of ​​the borehole to fall in and fill the cavity.

[0046] Specifically, step S311 in the example is divided into three stages: First, the charge preparation stage: For borehole number N045 (corresponding depths of -157.5m to -161m), Φ45mm emulsion explosive was used, with a charge density of 1.65g / cm³ and a linear charge weight of 2.3kg / m. Three detonation points were arranged inside the borehole, spaced 1.2m apart, using digital detonators to achieve a 15ms arithmetic delay.

[0047] Secondly, the detonation control stage: The circuit resistance value is detected by a blasting network analyzer, and the detonation command is triggered when the resistance fluctuation is ≤0.8Ω. After detonation, a composite stress field is formed: the radial compressive stress peak reaches 85MPa, the tangential tensile stress is 32MPa, and the effective fracture range covers the rock layer 3.8m below the bottom of the hole.

[0048] Finally, in the effect verification stage: a 3D laser scanner is used to obtain the bottom morphology of the hole after blasting. When the filling volume V ≥ 1.05V_d (design filling amount) and the block size D50 ≤ 40cm, the blasting is deemed qualified. Otherwise, a supplementary blasting procedure is initiated, with the supplementary blasting charge being 30%-50% of the original value.

[0049] In one embodiment, step S320 includes: S311a. After completing the hole enlargement construction and forming the current hole, the area corresponding to the number at the bottom of the current hole is taken as the current blasting area. Specifically, the engineering control unit incorporates a three-dimensional geographic information system, using multi-sensor fusion positioning technology to determine the current borehole bottom coordinates (e.g., X=32854.7, Y=49723.6, Z=-215.3). The blasting area is delineated using a dynamic grid division method, with the borehole bottom center as the origin, dividing the area into 0.5m × 0.5m grid units radially. Combined with data from ground-penetrating radar detecting the cavity boundaries, the blasting parameters corresponding to the N045 designation are automatically matched. During implementation, a total station monitors the borehole depth in real time. When the borehole bottom elevation deviates from the design value by more than ±0.2m, a parameter correction program is triggered, and the charge density is recalculated.

[0050] S311b: In the current blasting area, charge the explosive according to the current explosive equivalent and use directional controlled blasting to make the surrounding rock corresponding to the bottom area of ​​the hole fall in and fill the cavity, forming a new hole; S311c, Perform support work on the hole wall of the new hole; In one embodiment, step S323 includes; Initial and secondary support work is carried out on the walls of the new holes.

[0051] Specifically, the initial support and secondary lining are existing technologies and will not be elaborated here.

[0052] S311d, take the top of the new hole as the bottom position of the current hole, and repeat the step of taking the area corresponding to the number of the bottom position of the current hole as the current blasting area to support the hole wall of the new hole to form a new hole, until the surrounding rock and soil formed by the blasting fill the cavity to the preset elevation.

[0053] In one embodiment, prior to step S311d, the method further includes: S311e. Based on the preset survey data of the cavity, obtain the amount of surrounding rock and soil required to fill the cavity to the preset elevation; S311f. Based on the amount of surrounding rock debris, obtain the blasting height of the current hole; The engineering control unit retrieved the 3D laser scanning data of the solution cavity and calculated its volume as V = 1250 m³. Based on the rock mass loosening coefficient K = 1.35, the theoretical required slag volume was calculated to be Q = 1687.5 m³. During implementation, this was dynamically adjusted based on real-time monitoring data. Cavity Q real =V溶腔 (1 P)K Where P is the porosity of the rock mass after fracturing (measured average 23%), and when the actual filling volume reaches 1580m³, the system determines that the filling completion rate is 93.7%.

[0054] Step S311g: Based on the volume of surrounding rock and excavated soil, obtain the blasting height of the current borehole. The blasting height H is calculated using the formula:

[0055] In the formula, A is the cross-sectional area of ​​the hole (13.8 m²), and η is the blasting efficiency coefficient (taken as 0.92). When Q = 1687.5 m³, H = 118.6 m is calculated. During implementation, a segmented progressive method is adopted. After every 5 blasts, the actual filling volume is updated via three-dimensional laser scanning, and the remaining blasting height is dynamically adjusted.

[0056] S311h, Based on the blasting height, the number of blasts is obtained; Number of explosions Where h is the effective height of a single blast (3.5m). When H=118.6m, N=34 blasts. The engineering control unit considers variations in the rock mass integrity coefficient when generating the blasting sequence. When Kv≥0.6, h is 3.8m; when 0.4≤Kv<0.6, h is 3.2m; when Kv<0.4, a reinforcing blasting layer is inserted.

[0057] In one embodiment, step S400 includes: S410. After filling the cavity to the preset elevation, construct the wellhead structure of the vertical shaft in the preset construction area; Specifically, during the cavity filling stage, ground-penetrating radar scans the three-dimensional morphology data of the cavity in real time and uploads it to the central controller. The controller generates a grouting path plan based on preset elevation parameters and drives the grouting pump to inject cement-water glass dual-liquid grout into the cavity in a layered grouting mode. When the pressure sensor detects that the grouting pressure reaches the threshold of 0.8MPa-1.2MPa and the displacement gauge shows that the settlement at the top of the cavity is less than 3mm, the preset filling standard is determined to be met. At this point, the shaft head structure construction can begin in the preset construction area.

[0058] Of course, in some exemplary embodiments, step S410 includes: When the cavity is filled to the preset elevation, the shaft ring structure and the lock ring structure are constructed sequentially in the preset construction area to obtain the shaft opening structure; wherein, the lock ring structure is located inside the shaft ring structure.

[0059] S420. Excavation work is carried out on the inner side of the wellhead structure to create the vertical shaft.

[0060] The excavation operation adopts a layered reverse construction method, with the excavation depth of each layer controlled within 1.5m. After completing one cycle of excavation, the excavation operation is repeated until a vertical shaft is formed.

[0061] In one embodiment, step S420 includes: S421. Excavate downwards to the target height inside the wellhead structure to form the current foundation pit; Specifically, before excavation, the central controller, based on the preset target height parameters (usually set to 2.0m ± 0.2m) from the BIM model, drives the hydraulic breaker to form an annular cutting groove inside the wellhead structure. The cutting depth is fed back in real time by displacement sensors installed on the rock drill arm, and excavation automatically stops when the design elevation is reached, forming the current foundation pit.

[0062] S422. Perform support work on the current foundation pit to obtain the first foundation pit; The support operation employed a combined shotcrete and anchor bolt support process. More specifically, the shotcrete was primarily applied using a mechanical shotcrete arm, which automatically adjusted the spraying angle according to the pit's contour, applying C25 steel fiber reinforced concrete in three layers, with each layer's thickness controlled at 50mm and the interval between layers not exceeding 30 minutes. Anchor bolts were installed using an anchor bolt installation robot, specifically, Φ22 threaded steel anchor bolts were laid out in a 1.2m × 1.2m grid. The torque sensor (set to 180 N·m) was triggered to automatically stop the drilling when the depth reached 3.5m. After the support was completed, a concrete strength tester confirmed the well wall structure strength through ultrasonic testing (wave velocity ≥ 3500 m / s was considered acceptable), and the data was transmitted to the central control terminal, ultimately forming the first foundation pit.

[0063] S423. When the wall of the first foundation pit reaches the preset strength, repeat the steps of excavating downward to the target height inside the wellhead structure to form the current foundation pit, and then perform the support operation on the current foundation pit to obtain the first foundation pit, until the vertical shaft is formed.

[0064] During the cyclical operation phase, taking a vertical shaft with a design elevation of 65m as an example, the intelligent guidance system uses a laser line projector to check the center coordinate deviation of the shaft before each excavation (allowable value ±15mm). When a certain depth is reached (e.g., 15m), the ventilation and pressurization system is activated to maintain an air velocity of 0.5m / s and an oxygen concentration ≥19.5% at the working face. The drainage module uses a three-stage relay pump station, with an additional drainage unit added every 10m of descent. The flow controller automatically adjusts the pump power according to the seepage volume (adjustment range 5m³ / h-30m³ / h). The shaft structure is obtained at the design elevation of 65m.

[0065] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for constructing a large-diameter shaft of an extra-long tunnel, characterized by, The extra-long tunnel has a karst cavity formed within its building boundary, and the vertical shaft is configured corresponding to the karst cavity; the construction method for the large-diameter vertical shaft of the extra-long tunnel includes the following steps: In the pre-designated construction area, pilot holes are constructed along the direction extending downward from the shaft according to the first pre-designated diameter to obtain at least two target pilot holes spaced apart within the building boundary line of the shaft; wherein, the pre-designated construction area is located on the ground surface of the area where the shaft of the extra-long tunnel is located, and the bottom of the pilot holes extends and penetrates into the tunnel; When drilling reaches the bottom of each of the pilot holes, the current hole is obtained by enlarging the hole from the bottom of each of the target pilot holes upwards according to the second preset hole diameter, and the slag formed by drilling falls and fills the cavity; wherein, the size of the second preset hole diameter is larger than the size of the first preset hole diameter; After the borehole enlargement is completed and the bottom of the current borehole is formed, directional controlled blasting is used to cause the surrounding rock corresponding to the bottom of the borehole to fall in and fill the cavity. After filling the cavity to a preset elevation, excavation work is carried out in the preset construction area until the shaft is formed.

2. The method of claim 1, wherein the method further comprises: Before the step of using directional controlled blasting to cause the surrounding rock corresponding to the bottom area of ​​the borehole to fall into and fill the cavity at the bottom position of the borehole after the borehole enlargement construction is completed and the current borehole is formed, the method further includes: Based on the preset data of the shaft, determine the current explosive equivalent required to excavate to the preset diameter of the shaft using controlled blasting in the current hole; wherein, the preset data includes the preset diameter of the shaft, the distance between the current hole and the preset shaft wall, the surrounding rock data at the location of the shaft, and the geological data at the location of the shaft; The step of using directional controlled blasting to cause the surrounding rock corresponding to the bottom area of ​​the hole to fall into and fill the cavity after the hole enlargement construction is completed and the current hole is formed includes: After the borehole enlargement is completed and the bottom of the current borehole is formed, the surrounding rock corresponding to the bottom of the borehole is caused to fall into and fill the cavity by directional controlled blasting according to the current explosive equivalent.

3. The method according to claim 2, wherein After the step of determining the current explosive equivalent required to excavate to the preset diameter of the shaft using controlled blasting methods within the current borehole based on the preset data of the shaft, the method further includes: Based on the preset data of the shaft, the blasting impact height of the current explosive equivalent along the extension direction of the current hole is obtained; The number of blasts required for the vertical shaft is determined based on the height of the blasting impact.

4. The method of claim 2, wherein the method further comprises: Before the step of using directional controlled blasting to cause the surrounding rock corresponding to the bottom area of ​​the borehole to fall into and fill the cavity at the bottom position of the borehole after the borehole enlargement construction is completed and the current borehole is formed, the method further includes: The number of blasts is sequentially numbered according to the vertical shaft's extension direction from bottom to top; The step of using directional controlled blasting to cause the surrounding rock corresponding to the bottom area of ​​the hole to fall into and fill the cavity after the hole enlargement construction is completed and the current hole is formed includes: After the borehole enlargement is completed and the bottom of the current borehole is formed, directional controlled blasting is used to cause the surrounding rock corresponding to the bottom area of ​​the borehole to fall in and fill the cavity.

5. The construction method for large-diameter vertical shafts in extra-long tunnels as described in claim 4, characterized in that, The step of using directional controlled blasting to cause the surrounding rock corresponding to the bottom area of ​​the hole to fall into and fill the cavity at the bottom position of the hole after the hole enlargement construction is completed and the current hole is formed includes: After the hole enlargement construction is completed and the current hole is formed, the area corresponding to the number at the bottom of the current hole is taken as the current blasting area. In the current blasting area, explosives are loaded according to the current explosive equivalent and directional controlled blasting is used to cause the surrounding rock corresponding to the bottom area of ​​the hole to fall in and fill the cavity, forming a new hole; Support work is carried out on the walls of the new holes; The top of the new hole is taken as the bottom position of the current hole, and the step of taking the area corresponding to the number of the bottom position of the current hole as the current blasting area is repeated until the support operation of the hole wall of the new hole is performed to form a new hole, until the surrounding rock and soil formed by the blasting fill the cavity to the preset elevation.

6. The construction method for large-diameter vertical shafts in extra-long tunnels as described in claim 5, characterized in that, The process of setting the top of the new hole as the bottom position of the current hole, and repeatedly executing the step of setting the area corresponding to the number of the bottom position of the current hole as the current blasting area until the support operation on the hole wall of the new hole is performed to form a new hole, continues until the surrounding rock and soil formed by the blasting fill the cavity to the preset elevation, and further includes: Based on the pre-defined survey data of the cavity, the required volume of surrounding rock and soil to fill the cavity to the pre-defined elevation is obtained; Based on the volume of surrounding rock debris, the blasting height of the current hole is obtained; The number of blasts is determined based on the blasting height. The step of taking the top of the new hole as the bottom position of the current hole, and repeatedly executing the step of taking the area corresponding to the number of the bottom position of the current hole as the current blasting area, to supporting the hole wall of the new hole to form a new hole, until the surrounding rock and soil formed by the blasting fill the cavity to the preset elevation, includes: The top of the new hole is taken as the bottom position of the current hole, and the step of taking the area corresponding to the number of the bottom position of the current hole as the current blasting area to support the hole wall of the new hole is repeated until the blasting operation of the specified number of blasts is completed, so that the surrounding rock and soil formed by the blasting fill the cavity to the preset elevation.

7. The construction method for large-diameter vertical shafts in extra-long tunnels as described in claim 6, characterized in that, The step of supporting the wall of the new hole includes: Initial and secondary support work is carried out on the walls of the new holes.

8. The construction method for large-diameter vertical shafts in extra-long tunnels as described in any one of claims 1 to 7, characterized in that, The step of excavating in the preset construction area after filling the cavity to a preset elevation until the shaft is formed includes: After filling the cavity to the preset elevation, construct the wellhead structure of the vertical shaft in the preset construction area; Excavation work is carried out on the inner side of the wellhead structure to create the vertical shaft.

9. The construction method for large-diameter vertical shafts in extra-long tunnels as described in claim 8, characterized in that, The step of excavating inside the wellhead structure to create the vertical shaft includes: The target height is excavated downwards from the inside of the wellhead structure to form the current foundation pit; Support work is carried out on the current foundation pit to obtain the first foundation pit; When the walls of the first foundation pit reach a preset strength, the steps of excavating downward to the target height inside the wellhead structure to form the current foundation pit and then supporting the current foundation pit to obtain the first foundation pit are repeated at the bottom of the first foundation pit until the vertical shaft is formed.

10. The construction method for large-diameter vertical shafts in extra-long tunnels as described in claim 8, characterized in that, The step of constructing the wellhead structure of the vertical shaft in the preset construction area after filling the cavity to the preset elevation includes: When the cavity is filled to the preset elevation, the shaft ring structure and the lock ring structure are constructed sequentially in the preset construction area to obtain the shaft opening structure; wherein, the lock ring structure is located inside the shaft ring structure.

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