An excavation method for a small-section chamber and an obliquely intersecting sudden large-section chamber

Abstract

The present invention provides a method for excavating a small-section chamber into an obliquely intersecting and suddenly enlarged large-section chamber: excavate a temporary transverse passage along the interface to enter the preset large-section chamber; excavate a sidewall pilot tunnel in an upward inclination along the extending direction of the preset large-section chamber; continue to excavate a horizontal pilot tunnel after the arch foot of the sidewall pilot tunnel is tangent to the arch foot of the preset large-section chamber; pick the top of the horizontal pilot tunnel to expand and excavate the arch part I; excavate the arch part II along the sidewall of the arch part I; alternately and reversely press the top and blast to expand and brush the arch part along the end faces of the arch part I and the arch part II until the arch part of the sidewall pilot tunnel has a sufficient safety height from the arch springing line of the large-section chamber; reverse the process in the order of blasting and expanding the arch part at one time, excavating the top sidewall of the sidewall pilot tunnel, and excavating the side sidewall of the sidewall pilot tunnel to the starting end of the preset large-section chamber; excavate the remaining sidewalls in layers. The present invention can increase the underground excavation operation space of the chamber, reduce the number of temporary supports, improve the construction efficiency, and save the construction cost; reduce the blasting frequency, accelerate the lining closure, and ensure the stability of the surrounding rock.

Description

Technical Field

[0001] The present invention belongs to the technical field of mining, relates to a chamber construction technology, and in particular to an excavation method for a small-section chamber with an oblique intersection and sudden change to a large-section chamber. Background Art

[0002] A chamber is a spatial structure excavated and built underground in a mine for a specific purpose. Their sizes vary. Common small-section chambers include central substation chambers, skip chambers, sump and sludge discharge chambers, ventilation fan chambers, etc. Large-section chambers usually include ore unloading and loading chambers, crusher chambers, hoist chambers, underground repair chambers, etc. Small-section chambers are usually connected to large-section chambers to form the development and transportation system of the mine. Compared with small-section chambers, large-section chambers have characteristics such as larger space and more complex geological conditions. The increase in height and span makes their excavation more difficult. Therefore, how to ensure the stability of the surrounding rock during the excavation of large-section chambers and improve the excavation efficiency is one of the main problems faced by current underground mining projects in mines.

[0003] Currently, the methods for the sudden change from a small-section chamber to a large-section chamber can be divided into parallel sudden change and oblique intersection sudden change. The former is that the central axis of the small chamber section is parallel to the central axis of the large chamber section, and the latter is that the central axis of the small chamber section intersects with the central axis of the large chamber section. However, due to limitations such as terrain and excavation construction period, the construction process of oblique intersection sudden change is more complicated, and collapse accidents often occur during the excavation process. Existing excavation methods for small-section chambers with oblique intersection and sudden change to large-section chambers include: small pilot tunnel climbing and reverse expansion method, transverse tunnel large package method, CRD method conversion construction, up-picking tunnel method conversion construction, etc. These methods generally have the following disadvantages during construction:

[0004] 1) There is insufficient construction space during section conversion, large machinery cannot enter the tunnel, which affects the construction speed and prolongs the construction period;

[0005] 2) The amount of temporary support is large and the removal is frequent, which increases the cost and affects the construction speed at the same time;

[0006] 3) The arch part needs to be expanded and brushed more times, and the forming is slower, which is not conducive to early closure of the lining.

[0007] Therefore, it is urgent to develop a reliable excavation technology for small-section chambers with oblique intersection and sudden change to large-section chambers to solve the deficiencies of the existing technology. Summary of the Invention

[0008] In view of the above technical problems, the present invention provides an excavation method for a small-section chamber with an oblique intersection and sudden change to a large-section chamber, which is characterized by including the following steps:

[0009] S1: Measure and set out the lines along the intersection section of the small-section chamber and the preset large-section chamber, and excavate a temporary transverse tunnel to enter the preset large-section chamber;

[0010] S2: Incline and excavate the side-wall pilot tunnel of the climbing section upward along the extending direction of the preset large-section chamber from the end side-wall of the temporary cross-passage. The cross-sectional dimension of the side-wall pilot tunnel of the climbing section is the same as that of the temporary cross-passage.

[0011] S3: After the excavation of the side-wall pilot tunnel of the climbing section reaches the point where its arch foot is tangent to the arch foot of the preset large-section chamber, continue to excavate the horizontal pilot tunnel along the central axis of the end cross-section of the side-wall pilot tunnel of the climbing section until the end of the preset large-section chamber.

[0012] S4: Demolish the temporary support in the horizontal pilot tunnel, use the top of the horizontal pilot tunnel as the drilling platform, continue to pick the top and expand the excavation to the arch contour line of the preset large-section chamber, shape the expanded arch part I and conduct the initial support according to the support parameters of the chamber.

[0013] S5: Use the side-wall of the arch part I as the drilling platform to excavate the arch part II, then shape the expanded arch part II and conduct the initial support according to the support parameters of the chamber.

[0014] S6: Use the end faces of the arch part I and the arch part II as the drilling platforms, conduct alternate reverse roof pressing blasting operations from the end faces of the arch part I and the arch part II to excavate the remaining arch part, and excavate the corresponding side-wall after each single alternation is completed.

[0015] S7: Push backward to the starting end of the preset large-section chamber in the order of blasting and expanding the arch part at one time, excavating the top side-wall of the side-wall pilot tunnel of the climbing section, and excavating the side side-wall of the side-wall pilot tunnel of the climbing section.

[0016] S8: Excavate the remaining side-walls in layers.

[0017] In the above excavation method for the small-section chamber obliquely intersecting and suddenly changing to a large-section chamber, in step S1, the width of the temporary cross-passage is half of the width of the large-section chamber, and the height of the temporary cross-passage is the same as the arch height of the large-section chamber.

[0018] In the above excavation method for the small-section chamber obliquely intersecting and suddenly changing to a large-section chamber, in step S2, the position of the side-wall pilot tunnel of the climbing section is determined according to the driving depth of the temporary cross-passage. The starting excavation surface of the side-wall pilot tunnel of the climbing section is located at the side-wall of the temporary cross-passage. Before construction, first measure and set out the lines according to the excavation contour line, then blast and level the two side areas of the arch of the temporary cross-passage, and then excavate the side-wall pilot tunnel of the climbing section along the excavation contour line. The slope of the side-wall pilot tunnel of the climbing section is calculated by the following formula: In the formula, θ represents the slope of the side-wall pilot tunnel of the climbing section; H represents the height of the large-section chamber; L represents the length of the large-section chamber; h represents the arch height of the large-section chamber; d represents the width of the small-section chamber; l represents the length of the horizontal pilot tunnel at the end of the side-wall pilot tunnel of the climbing section;h' Denote the arch height of the sidewall pilot tunnel in the climbing section; l'' Denote the distance between the temporary cross passage and the proximal section of the large-section chamber.

[0019] In the above excavation method of the small-section chamber obliquely intersecting and suddenly changing to a large-section chamber, in step S1, the driving depth of the temporary cross passage is determined according to the location of the sidewall pilot tunnel in the climbing section; when the rock property in the area is poor, the sidewall pilot tunnel in the climbing section should be set at the proximal sidewall of the large-section chamber according to the principle of proximity. At this time, the driving depth of the temporary cross passage should be the same as the width of the sidewall pilot tunnel in the climbing section; when the rock property in the area is good, the sidewall pilot tunnel in the climbing section should be driven to the distal sidewall of the large-section chamber. At this time, the driving depth of the temporary cross passage is the same as the width of the large-section chamber.

[0020] In the above excavation method of the small-section chamber obliquely intersecting and suddenly changing to a large-section chamber, in step S6, during the alternate reverse roof-pressing blasting operation, first remove the temporary support at the arch of the sidewall pilot tunnel in the climbing section for the unit blasting depth, then blast and level the two side areas at the arch of the sidewall pilot tunnel in the climbing section, then expand and brush arch I and arch II according to the design requirements and carry out temporary support, and finally expand and brush sidewall III. The expansion and brushing of sidewall III is carried out from top to bottom, and the single-time expansion and brushing height does not exceed 2m.

[0021] In the above excavation method of the small-section chamber obliquely intersecting and suddenly changing to a large-section chamber, in step S6, blasting twice in one alternate reverse roof-pressing blasting operation can accelerate the forming efficiency of the arch of the large-section chamber, and then carry out support on it, so as to accelerate the early closure of the arch lining of the large-section chamber.

[0022] In the above excavation method of the small-section chamber obliquely intersecting and suddenly changing to a large-section chamber, in step S6, the alternate reverse roof-pressing blasting operation n times later, when the contour line of the arch of the sidewall pilot tunnel in the climbing section is tangent to the springing line of the large-section chamber, then carry out n' times of alternate reverse roof-pressing blasting operation, so that when the remaining arch is formed by one-time blasting in subsequent segments, the arch of the sidewall pilot tunnel in the climbing section has a sufficient safety height from the springing line of the large-section chamber h'' , thereby reducing the disturbance degree of blasting on the sidewall pilot tunnel in the climbing section and ensuring its stability; where the safety height h'' can be calculated by the following formula: Wherein, n' needs to meet the following conditions: In the formula, n' is the number of times of continuing reverse alternate roof-pressing when the arch of the large-section chamber is expanded and brushed to the tangent of the contour line of the arch of the sidewall pilot tunnel in the climbing section and the springing line of the large-section chamber; θ Denote the slope of the sidewall pilot tunnel in the climbing section; L Denote the length of the large-section chamber; d Denote the width of the small-section chamber;h' Denotes the arch height of the side wall pilot tunnel in the climbing section; l Denotes the length of the horizontal pilot tunnel at the end of the side wall pilot tunnel in the climbing section; l' Is the driving depth for a single blast; l'' Denotes the distance between the temporary cross passage and the proximal section of the large-section chamber.

[0023] In the above excavation method for the small-section chamber obliquely intersecting and mutating into a large-section chamber, in step S7, the arch parts I+II of the large-section chamber are formed by a single blast and temporarily supported, then the temporary support of the side wall pilot tunnel in the climbing section is removed, the side wall parts I"+II" are excavated, and finally the side wall part III' is excavated. The side wall III' is enlarged and brushed from top to bottom, and the single-time enlargement and brushing height does not exceed 2m.

[0024] In the above excavation method for the small-section chamber obliquely intersecting and mutating into a large-section chamber, the remaining side wall is a slope. First, it is stratified by height, and then it is excavated layer by layer from top to bottom.

[0025] In the above excavation method for the small-section chamber obliquely intersecting and mutating into a large-section chamber, in step S8, the overall slope is divided into n layers of slope sections; then each single-layer slope section is divided into an inclined section ① and a straight wall section ②;

[0026] The excavation sequence of the single-layer slope section is: first, excavate the inclined section ① from top to bottom along the slope surface of the corresponding section, and then, taking the area where the original inclined section ① is located as the working space, excavate the straight wall section ② from outside to inside. After the excavation is completed, timely support the side wall of the corresponding section;

[0027] The number of layers into which the overall slope is stratified can be calculated by the following formula: where, h''' needs to meet the following conditions:

[0028] In the formula, H Denotes the height of the large-section chamber; h Denotes the arch height of the large-section chamber; h' Denotes the arch height of the side wall pilot tunnel in the climbing section; h''' Denotes the height of a single-layer slope section.

[0029] Compared with the prior art, the excavation method for the small-section chamber obliquely intersecting and mutating into a large-section chamber has the following beneficial effects:

[0030] 1. In the present invention, first, according to the specifications of the large-section chamber, a hole is gradually obliquely opened upward along the side wall of the preset large chamber, and horizontal pilot tunnels are arranged at both ends of the inclined pilot tunnel. By utilizing the structural characteristics of the geology and combining with the small-section size of the pilot tunnel, the inclined pilot tunnel is easy to support and has strong stability, which can not only improve the excavation efficiency but also reduce the support difficulty.

[0031] 2. The present invention expands and excavates a large-section chamber in a reverse direction from top to bottom through an inclined pilot tunnel. By using the inclined angle of the inclined pilot tunnel from top to bottom, the muck transportation efficiency during the excavation process is greatly improved, which is conducive to realizing the feasibility, stability, and convenience of expanding the large-section chamber.

[0032] 3. The present invention can increase the operation space range during the concealed excavation of a large-section chamber, which is beneficial to the application of construction equipment and can speed up the construction speed.

[0033] 4. The present invention can reduce the number of blasts during the excavation of the arch part, reduce the disturbance of the surrounding rock by blasting, and is beneficial to the early closure of the lining.

[0034] 5. The present invention can reduce the amount of temporary support during the excavation of the chamber, reduce the frequency of support removal, thereby saving construction costs and speeding up the construction progress at the same time.

[0035] 6. When excavating the slope-type side wall, the layered excavation method provided by the present invention can avoid potential landslide disasters caused by slope cutting. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0037] Figure 1 It is a schematic structural diagram of the present invention.

[0038] Figure 2 It is a schematic diagram of the excavation section at the starting end of the side wall pilot tunnel in the climbing section of the present invention.

[0039] Figure 3 It is a schematic diagram for calculating relevant parameters of the present invention.

[0040] Figure 4 It is a schematic diagram of the reverse excavation of the arch part and the corresponding side wall of the large-section chamber of the present invention.

[0041] Figure 5 It is a schematic diagram of the reverse excavation of the arch part of the large-section chamber of the present invention.

[0042] Figure 6 It is a schematic diagram of the excavation section of the side wall of the large-section chamber of the present invention.

[0043] Figure 7 It is a schematic diagram of the remaining side wall of the large-section chamber of the present invention.

[0044] Figure 8 It is a schematic diagram of the excavation of the remaining side wall of the large-section chamber of the present invention.

[0045] Figure 9 Schematic diagram of the calculation results of relevant parameters for the embodiment of the present invention.

[0046] Figure 10 Schematic diagram of the excavation of the remaining side wall of the large-section chamber for the embodiment of the present invention.

[0047] Figure 1 In the figure, 1. Small-section chamber; 2. Temporary transverse passage; 3. Sidewall pilot tunnel of the climbing section; 4. Horizontal pilot tunnel; 5. Large-section chamber. Detailed implementation manners

[0048] The following are specific embodiments of the present invention. In combination with the accompanying drawings, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0049] As Figures 1 to 10 shown, the excavation method of the small-section chamber obliquely intersecting and mutating into a large-section chamber includes the following steps:

[0050] S1: Measure and set out the line along the intersection section of the small-section chamber 1 and the preset large-section chamber 5, and excavate the temporary transverse passage 2 to enter the preset large-section chamber 5;

[0051] S2: Incline and excavate the sidewall pilot tunnel 3 of the climbing section along the extension direction of the preset large-section chamber 5 from the end sidewall of the temporary transverse passage 2. The cross-sectional dimension of the sidewall pilot tunnel 3 of the climbing section is the same as that of the temporary transverse passage 2;

[0052] S3: After the sidewall pilot tunnel 3 of the climbing section is excavated until its arch foot is tangent to the arch foot of the preset large-section chamber 5, continue to excavate the horizontal pilot tunnel 4 along the central axis of the end section of the sidewall pilot tunnel 3 of the climbing section to the end of the preset large-section chamber 5. The excavation length of the horizontal pilot tunnel 4 needs to meet the operation space requirements.

[0053] S4: Remove the temporary support in the horizontal pilot tunnel 4, use the top of the horizontal pilot tunnel 4 as a drilling platform, continue to pick the top and expand the excavation to the arch contour line of the preset large-section chamber 5, form and expand the arch part I and carry out the initial support according to the chamber support parameters;

[0054] S5: Use the sidewall of the arch part I as a drilling platform to excavate the arch part II, then form and expand the arch part II and carry out the initial support according to the chamber support parameters;

[0055] S6: Take the end faces of the arch part I and the arch part II as the drilling platforms, and carry out alternate reverse roof pressing blasting operations from the end faces of the arch part I and the arch part II to excavate the remaining arch part. After each single alternation is completed, the corresponding side wall is excavated.

[0056] S7: Advance in the reverse order of blasting and expanding the arch part at one time, excavating the top side wall of the side wall pilot tunnel 3 in the climbing section, and excavating the side side wall of the side wall pilot tunnel 3 in the climbing section to the starting end of the preset large-section chamber 5.

[0057] S8: Excavate the remaining side walls in layers.

[0058] Preferably, in step S1, the width of the temporary cross passage 2 is half of the width of the large-section chamber 5, and the height of the temporary cross passage 2 is the same as the arch height of the large-section chamber 5.

[0059] Preferably, in step S2, the position of the side wall pilot tunnel 3 in the climbing section is determined according to the driving depth of the temporary cross passage 2. The starting excavation surface of the side wall pilot tunnel 3 in the climbing section is located at the side wall of the temporary cross passage 2. Before construction, first measure and set out the line according to the excavation contour line, then blast and level the two side areas A and B of the arch part of the temporary cross passage 2, and then excavate the side wall pilot tunnel 3 in the climbing section along the excavation contour line. The slope of the side wall pilot tunnel 3 in the climbing section is calculated by the following formula In the formula, θ represents the slope of the side wall pilot tunnel in the climbing section; H represents the height of the large-section chamber; L represents the length of the large-section chamber; h represents the arch height of the large-section chamber; d represents the width of the small-section chamber; l represents the length of the horizontal pilot tunnel at the end of the side wall pilot tunnel in the climbing section; h' represents the arch height of the side wall pilot tunnel in the climbing section; l'' represents the distance between the temporary cross passage and the proximal section of the large-section chamber.

[0060] Preferably, in step S1, the driving depth of the temporary cross passage 2 is determined according to the position of the side wall pilot tunnel 3 in the climbing section; when the rock property of the area is poor, the side wall pilot tunnel 3 in the climbing section should be placed at the proximal side wall of the large-section chamber 5 according to the principle of proximity. At this time, the excavation depth of the temporary cross passage 2 should be the same as the width of the side wall pilot tunnel 3 in the climbing section to reduce the unloading range of the surrounding rock excavation; when the rock property of the area is good, the side wall pilot tunnel 3 in the climbing section should be driven to the distal side wall of the large-section chamber 5. At this time, the excavation depth of the temporary cross passage 2 is the same as the width of the large-section chamber 5 to increase the stacking area of waste and ore temporary sites, improve the unit transportation volume and reduce the transportation times.

[0061] Preferably, in step S6, taking the axis of the cross-section of the large-section chamber 5 as the boundary, the arch part of the large-section chamber 5 to be excavated on the side where the ramp-section side drift 3 is located presents a partial excavation state, resulting in an asymmetric stress distribution in the arches to be excavated on both sides. The excavated part is in an arc shape, leading to easy damage to the surrounding rock in the stress concentration area and being more significantly affected by blasting. Therefore, during the alternate reverse crown blasting operation, first remove the temporary support at the arch of the ramp-section side drift 3 for the unit blasting depth, then blast and level the two side areas I' and II' at the arch of the ramp-section side drift 3, then expand and brush the arches I and II according to the design requirements and carry out temporary support, and finally expand and brush the side wall III. The expansion and brushing of the side wall III are carried out from top to bottom, and the single-time expansion and brushing height does not exceed 2 m.

[0062] Preferably, in step S6, blasting twice in one alternate reverse crown blasting operation can accelerate the forming efficiency of the arch of the large-section chamber 5, and then carry out support on it, so as to accelerate the early closure of the lining of the arch of the large-section chamber 5.

[0063] Preferably, in step S6, the alternate reverse crown blasting operation n times, when the contour line of the arch of the ramp-section side drift 3 is tangent to the springing line of the large-section chamber 5, then carry out n' times of alternate reverse crown blasting operations, so that when the remaining arch part is formed by one-time blasting in subsequent segments, the arch of the ramp-section side drift 3 has a sufficient safety height from the springing line of the large-section chamber 5 h'' , thereby reducing the disturbance degree of blasting to the ramp-section side drift 3 and ensuring its stability; where the safety height h'' can be calculated by the following formula: Among them, n' needs to meet the following conditions: In the formula, n' is the number of times of continuing reverse alternate crown pressing when the arch of the large-section chamber is expanded and brushed to the point where the contour line of the arch of the ramp-section side drift is tangent to the springing line of the large-section chamber; θ represents the slope of the ramp-section side drift; L represents the length of the large-section chamber; d represents the width of the small-section chamber; h' represents the arch height of the ramp-section side drift; l represents the length of the horizontal drift at the end of the ramp-section side drift; l' is the single-time blasting tunneling depth; l'' represents the distance between the temporary cross-passage and the proximal cross-section of the large-section chamber.

[0064] Preferably, in step S7, the I+II part of the arch of the large-section chamber 5 is formed by one-time blasting and temporarily supported, then the temporary support of the side wall pilot tunnel 3 of the climbing section is removed, the I"+II" part of the side wall is excavated, and finally the III' part of the side wall is excavated. The expansion and brushing of the III' part of the side wall are carried out from top to bottom, and the single-time expansion and brushing height does not exceed 2m. This can reduce the number of times of blasting disturbance to the surrounding rock and further accelerate the early closure of the lining of the arch of the large-section chamber 5.

[0065] Preferably, the remaining side wall is a slope. First, it is stratified according to height, and then it is excavated layer by layer from top to bottom. This can prevent the high and steep cutting slope formed by excavating from the toe of the slope from destroying the original stress balance of the slope and avoid landslide disasters during the excavation process.

[0066] Preferably, in step S8, the overall slope is divided into n slope sections; then the single-layer slope section is divided into an inclined section ① and a straight wall section ②;

[0067] The excavation sequence of the single-layer slope section is: first, the inclined section ① is excavated from top to bottom along the slope surface of the corresponding section, and then the straight wall section ② is excavated from outside to inside with the area where the original inclined section ① is located as the working space. After the excavation is completed, the side wall of the corresponding section is supported in time;

[0068] The number of layers into which the overall slope is divided can be calculated by the following formula: Among them, h''' The following conditions need to be met: In the formula, H represents the height of the large-section chamber; h represents the arch height of the large-section chamber; h' represents the arch height of the side wall pilot tunnel of the climbing section; h''' represents the height of the single-layer slope section.

[0069] Taking a tuff mine exploitation project as an example, in the design scheme, the preset large-section chamber is a maintenance chamber, with a length of 35m, a width of 15.5m, a height of 13.8m, and an arch height of 5.8m. It is intended to be expanded by a small-section belt chamber that intersects obliquely with it. The cross-sectional size of the belt chamber is 8m×7m, and the arch height is 3.2m. The distance between the intersection section and the starting end of the maintenance chamber is 1.7m, and the reserved horizontal pilot tunnel length is 4m. After on-site investigation, the joint fissures in this area are not well developed, no fault structures are found, the basic quality grade of the tuff rock mass is grade III, the weathering degree is relatively low, and the rock strength is relatively high. As Figures 1 to 10 shown, the excavation method for the small-section chamber intersecting obliquely and mutating into a large-section chamber includes the following steps:

[0070] S1: Measure and set out the line along the intersection section of the small-section chamber 1 and the preset large-section chamber 5, and excavate a temporary cross passage 2 to the far-end side wall of the preset large-section chamber 5. The cross-sectional size of the temporary cross passage is 7.25m×5.8m, and the arch height is 3m;

[0071] S2: Incline upwards and excavate the sidewall pilot tunnel 3 of the climbing section along the extending direction of the preset large-section chamber 5 from the end sidewall of the temporary cross-passage 2. The cross-sectional dimension of the sidewall pilot tunnel 3 of the climbing section is 7.25 m × 5.8 m. After calculation, the excavation gradient is 13.7°.

[0072] S3: After the excavation of the sidewall pilot tunnel 3 of the climbing section reaches the point where its arch foot is tangent to the arch foot of the preset large-section chamber 5, continue to excavate the horizontal pilot tunnel 4 along the central axis of the end cross-section of the sidewall pilot tunnel 3 of the climbing section to the end of the preset large-section chamber 5. The excavation length of the horizontal pilot tunnel 4 is 4 m.

[0073] S4: Remove the temporary support in the horizontal pilot tunnel 4, use the top of the horizontal pilot tunnel 4 as a drilling platform, continue to pick the top and expand the excavation to the arch contour line of the preset large-section chamber 5, form and expand the arch part I and conduct the initial support according to the chamber support parameters.

[0074] S5: Use the sidewall of the arch part I as a drilling platform to excavate the arch part II, then form and expand the arch part II and conduct the initial support according to the chamber support parameters.

[0075] S6: Use the end faces of the arch part I and the arch part II as drilling platforms. First, remove the temporary support of the arch of the sidewall pilot tunnel 3 of the climbing section with a unit blasting depth, then conduct blasting and trimming on the two side areas I' and II' of the arch of the sidewall pilot tunnel 3 of the climbing section, and then conduct alternate reverse roof pressing blasting operations from the end faces of the arch part I and the arch part II to excavate the remaining arch part. The single-cycle alternate footage is 3.5 m. When the arch contour line of the sidewall pilot tunnel 3 of the climbing section is tangent to the springing line of the large-section chamber 5, that is, when the total alternate excavation footage is 12.3 m, conduct 1 more alternate reverse roof pressing blasting operation. At this time, the safe height of the arch of the sidewall pilot tunnel 3 of the climbing section from the springing line of the large-section chamber 5 is 0.85 m. After each single-cycle alternate is completed, excavate the corresponding sidewall. The sidewall is excavated by layered blasting, operating from top to bottom, and the single-layer height does not exceed 2 m.

[0076] S7: Push backwards in the order of blasting and expanding the arch part at one time, excavating the top sidewall of the sidewall pilot tunnel 3 of the climbing section, and excavating the side sidewall of the sidewall pilot tunnel 3 of the climbing section to the starting end of the preset large-section chamber 5. The single-blasting footage is 3.5 m, and the total blasting footage is 18.7 m. After each single blasting is completed, use the layered blasting excavation method to excavate the corresponding sidewall, operating from top to bottom, and the single-layer height does not exceed 2 m.

[0077] S8: The remaining side wall is a slope with a length of 25.3 m, a height of 5.2 m, a width of 15.5 m, and a slope of 13.7°. The slope is divided into 3 layers, and each single-layer slope is further divided into an inclined section and a straight wall section. From top to bottom, they are as follows: the first-layer slope section has a length of 8.9 m, a height of 1.2 m, an inclined section with a length of 4.9 m, and a straight wall section with a length of 4 m; the second-layer slope section has a length of 17.1 m, a height of 2 m, an inclined section with a length of 8.2 m, and a straight wall section with a length of 8.9 m; the third-layer slope section has a length of 25.3 m, a height of 2 m, an inclined section with a length of 8.2 m, and a straight wall section with a length of 17.1 m.

[0078] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains may make various modifications or supplements to the described specific embodiments or use similar means for substitution, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0079] Although terms such as small cross-section chamber 1; temporary transverse passage 2; sidewall pilot tunnel in the climbing section 3; horizontal pilot tunnel 4; large cross-section chamber 5, etc. are used more frequently in this article, the possibility of using other terms is not excluded. The use of these terms is only for more convenient description and explanation of the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

[0080] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. 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 situations.

Claims

1. An excavation method for a small-section chamber with an obliquely intersecting sudden change to a large-section chamber, characterized in that, It includes the following steps: S1: Measure and set out the lines along the intersection section of the small-section chamber and the preset large-section chamber, and excavate a temporary cross-passage to enter the preset large-section chamber; S2: Incline and excavate the sidewall pilot tunnel of the climbing section along the extending direction of the preset large-section chamber from the end sidewall of the temporary cross-passage. The cross-sectional dimension of the sidewall pilot tunnel of the climbing section is the same as that of the temporary cross-passage; S3: After the excavation of the sidewall pilot tunnel of the climbing section reaches the point where its arch foot is tangent to the arch foot of the preset large-section chamber, continue to excavate the horizontal pilot tunnel along the central axis of the end section of the sidewall pilot tunnel of the climbing section to the end of the preset large-section chamber; S4: Remove the temporary support in the horizontal pilot tunnel, use the top of the horizontal pilot tunnel as a drilling platform, continue to pick the top and expand the excavation to the arch contour line of the preset large-section chamber, shape and expand the arch part I and carry out the initial support according to the chamber support parameters; S5: Use the sidewall of the arch part I as a drilling platform to excavate the arch part II, then shape and expand the arch part II and carry out the initial support according to the chamber support parameters; S6: Use the end faces of the arch part I and the arch part II as drilling platforms, and carry out alternate reverse roof pressing blasting operations from the end faces of the arch part I and the arch part II to excavate the remaining arch part. After each single alternation is completed, excavate the corresponding sidewall; In step S6, during the alternate reverse roof pressing blasting operation, first remove the temporary support of the arch part of the sidewall pilot tunnel of the climbing section with a unit blasting depth, then blast and level the two side areas of the arch part of the sidewall pilot tunnel of the climbing section, then expand and brush the arch part I and the arch part II according to the design requirements and carry out temporary support, and finally expand and brush the sidewall III. The expansion and brushing of the sidewall III is carried out from top to bottom, and the single expansion and brushing height does not exceed 2m; In step S6, blasting twice in one alternate reverse roof pressing blasting operation speeds up the forming efficiency of the arch part of the large-section chamber, and then carry out support on it, so as to accelerate the early closure of the arch lining of the large-section chamber; S7: Push backward in the order of blasting and expanding the arch part at one time, excavating the top sidewall of the sidewall pilot tunnel of the climbing section, and excavating the side sidewall of the sidewall pilot tunnel of the climbing section to the starting end of the preset large-section chamber; S8: Excavate the remaining sidewall in layers; In step S8, the remaining sidewall is a slope. First, layer it by height, and then excavate it layer by layer from top to bottom.

2. The excavation method of the inclined intersection sudden large-section chamber from a small-section chamber as described in claim 1, characterized in that, In the said step S1, the width of the temporary cross-passage is half of the width of the large-section chamber, and the height of the temporary cross-passage is the same as the arch height of the large-section chamber.

3. The excavation method of the inclined and abruptly changed large-section chamber from a small-section chamber as claimed in claim 1, wherein In the said step S2, the position of the sidewall pilot tunnel of the climbing section is determined according to the driving depth of the temporary cross-passage. The starting excavation surface of the sidewall pilot tunnel of the climbing section is located at the sidewall of the temporary cross-passage. Before construction, measure and set out the lines according to the excavation contour line first, then blast and level the two side areas of the arch part of the temporary cross-passage, and then excavate the sidewall pilot tunnel of the climbing section along the excavation contour line. The slope of the sidewall pilot tunnel of the climbing section is calculated by the following formula: In the formula, θ represents the slope of the sidewall pilot tunnel in the climbing section; H represents the height of the large-section chamber; L represents the length of the large-section chamber; h represents the arch height of the large-section chamber; d represents the width of the small-section chamber; l represents the length of the horizontal pilot tunnel at the end of the sidewall pilot tunnel in the climbing section; h' represents the arch height of the sidewall pilot tunnel in the climbing section; l'' represents the distance between the temporary transverse passage and the proximal section of the large-section chamber.

4. The excavation method of the small-section chamber with an oblique intersection and sudden change to a large-section chamber as claimed in claim 3, characterized in that, In the step S1, the driving depth of the temporary cross-passage is determined according to the position of the side drift in the climbing section; when the rock property in the area is poor, the side drift in the climbing section should be arranged at the proximal side wall of the large-section chamber according to the principle of proximity, and at this time, the excavation depth of the temporary cross-passage should be the same as the width of the side drift in the climbing section; when the rock property in the area is good, the side drift in the climbing section should be driven to the distal side wall of the large-section chamber, and at this time, the excavation depth of the temporary cross-passage is the same as the width of the large-section chamber.

5. The excavation method of the small-section chamber with an obliquely intersecting sudden change to a large-section chamber as claimed in claim 1, characterized in that, In the step S6, after n alternating reverse roof pressing blasting operations, when the contour line of the arch of the sidewall pilot tunnel in the climbing section is tangent to the springing line of the large-section chamber, n' more alternating reverse roof pressing blasting operations are carried out so that when the remaining arch is formed by one-time blasting in subsequent segments, the arch of the sidewall pilot tunnel in the climbing section has a sufficient safety height from the springing line of the large-section chamber h'' , thereby reducing the disturbance degree of blasting on the sidewall pilot tunnel in the climbing section and ensuring its stability; Among them, the safety height h'' can be calculated by the following formula: Wherein, n' the following conditions need to be satisfied: In the formula, n' is the number of times of alternately pressing the top in the reverse direction when the arch part of the large-section chamber is expanded and brushed to the arch contour line of the side-wall pilot tunnel in the climbing section and is tangent to the springing line of the large-section chamber; θ represents the slope of the side-wall pilot tunnel in the climbing section; L represents the length of the large-section chamber; d represents the width of the small-section chamber; h' represents the arch height of the side-wall pilot tunnel in the climbing section; l represents the length of the horizontal pilot tunnel at the end of the side-wall pilot tunnel in the climbing section; l' is the single-shot tunneling depth; l'' represents the distance between the temporary cross-passage and the proximal section of the large-section chamber.

6. The excavation method of the small-section chamber with an obliquely intersecting sudden change to a large-section chamber according to claim 1, characterized in that In the step S7, the arch parts I + II of the large-section chamber are formed by one-time blasting and temporarily supported, then the temporary support of the side drift in the climbing section is removed, the side wall parts I" + II" are excavated, and finally the side wall part III' is excavated. The enlargement and brushing of the side wall part III' are carried out from top to bottom, and the single-time enlargement and brushing height does not exceed 2 m.

7. The excavation method of the inclined intersection sudden change large-section chamber from the small-section chamber as described in claim 1, characterized in that, In the step S8, the overall slope is divided into n layers of slope segments; and then each single-layer slope segment is divided into an inclined segment ① and a straight wall segment ②; The excavation sequence of the single-layer slope section is as follows: first, the inclined section ① is excavated from top to bottom along the slope of the corresponding section, and then the straight wall section ② is excavated from outside to inside with the area where the original inclined section ① is located as the working space. After the excavation is completed, the side wall of the corresponding section is supported in time. The number of layers of the overall slope can be calculated by the following formula: Wherein, h''' The following conditions need to be satisfied: In the formula, H represents the height of the large-section chamber; h represents the arch height of the large-section chamber; h' represents the arch height of the sidewall pilot tunnel in the climbing section; h''' represents the height of the single-layer slope section.

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