Over-excavation control method suitable for integrity surrounding rock tunnel

Abstract

The invention discloses an over-excavation control method suitable for an integrity surrounding rock tunnel, which belongs to the technical field of tunnel blasting excavation construction, and comprises the following seven steps in sequence: upper circulation primary concrete spraying, survey setting out and blast hole position positioning, peripheral hole drilling operation, charging detonation, danger removal and deslagging, primary support construction and circulation of the six steps. According to the scheme, the overexcavation amount is reduced, the construction efficiency is improved, and the construction cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of tunnel blasting excavation construction, and provides a method for controlling overbreak in tunnels with intact surrounding rock, which can reduce the overbreak amount, improve the construction efficiency and reduce the construction cost. Background Technique

[0002] At present, the excavation of tunnels such as highways and railways still mainly uses the blasting excavation process. After excavation, regardless of the surrounding rock category, the initial support needs to be constructed in time, and the support is close to the face. However, this practice causes the peripheral holes in the next cycle to be affected by the initial support working surface in the previous cycle, with a large outward inclination angle, and the hole bottom position far exceeds the designed blasting excavation contour line, resulting in serious overbreak at the hole bottom after blasting. This not only affects the stability of the tunnel surrounding rock, but also increases the amount of subsequent backfilled shotcrete, prolongs the operation time, and increases the construction cost.

[0003] Especially in tunnels with intact surrounding rock such as mudstone and sandstone, although the surrounding rock grade is low, the self-stabilizing ability is strong, and its self-bearing capacity is not fully utilized. Therefore, it is necessary to study a method for controlling overbreak in tunnels with intact surrounding rock to make full use of the self-bearing capacity of the surrounding rock, reduce blasting overbreak, save construction costs, and improve construction efficiency. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for controlling overbreak in tunnels with intact surrounding rock, which can reduce the overbreak amount, improve the construction efficiency and reduce the construction cost.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a method for controlling overbreak in tunnels with intact surrounding rock, which includes the following steps:

[0007] The first step is to spray concrete initially in the previous cycle.

[0008] After the blasting excavation and mucking for risk removal are completed, immediately construct the initial spray concrete in the initial support of the previous cycle to seal the surrounding rock surface and reserve the reserved spacing required for subsequent drilling operations.

[0009] The second step is to measure and set out the positions of the blast holes.

[0010] After the initial spray concrete in the first step is completed, the survey team accurately measures and sets out the excavation contour line, the positions of the cut holes and the positions of the auxiliary holes according to the blasting design.

[0011] The third step is the drilling operation of the peripheral holes.

[0012] The drillers drill the peripheral holes according to the measured positions of the peripheral holes at the excavation contour line.

[0013] First, drill the peripheral holes at the positions of the vault and the two side arch waists as the peripheral reference holes for drilling the remaining peripheral holes subsequently. The depth of the peripheral reference holes is 1 m.

[0014] Then, starting from the three peripheral reference holes at the vault and the two side arch waists as the reference basis, drill the remaining peripheral holes subsequently. Specifically, drill the remaining peripheral holes on both sides of the three peripheral reference holes respectively. When drilling the remaining peripheral holes, the drill rod angle refers to the installed drill rod angle in the peripheral reference hole it is close to.

[0015] Finally, for the drilling operations of the cut holes at the cut hole positions and the auxiliary holes at the auxiliary hole positions, extend the drilling direction line outward on the design drawing in advance, and use the intersection point with the designed drilling depth as the pre-positioned drill worker's standing position. The drill worker stands the drilling rig at the intersection point to conduct the drilling operations for the cut holes and the auxiliary holes.

[0016] Fourth step, charge and initiate the blast.

[0017] Load the blasting materials according to the blasting design and connect the network for initiation.

[0018] Fifth step, remove hazards and muck out.

[0019] After blasting, after the blasting engineering technicians check and confirm that there is no problem, conduct mucking out and hazard removal.

[0020] Sixth step, apply the initial support.

[0021] Install the ring steel support and the steel mesh in the initial shotcrete of the previous cycle, and then re-spray the concrete to the designed thickness to achieve the initial shotcrete closure of the excavation face of this cycle.

[0022] Seventh step, cyclic operation.

[0023] Carry out the cycle according to the above steps 1 to 6. When the monitored measurement data changes greatly or the surrounding rock geological conditions deteriorate significantly, adjust the reserved spacing.

[0024] To control the external insertion angle of the peripheral holes and reduce the overbreak amount, in the above solution, further: during the drilling operation of the peripheral holes, drill by gradually replacing and lengthening the drill rods.

[0025] To effectively control the accuracy of the external insertion angle of the peripheral holes, in the above solution, further: during the drilling operation of the peripheral holes, use 1 m drill rods for the first drilling, and gradually replace them with 2 m and 3 m drill rods until the peripheral holes are drilled and formed.

[0026] To include reserving the subsequent drilling operation space, reduce the external insertion angle of the peripheral holes, and reduce the overbreak amount, in the above solution, further: in the seventh step, the adjustment of the reserved spacing is carried out according to the monitored measurement data.

[0027] When the monitored settlement rate is 0.2 mm / d, the reserved spacing is increased to 3.5 m - 4.5 m; when the monitored settlement rate is 0.2 - 1.0 mm / d, the reserved spacing is increased to 2.5 m - 3.5 m; when the monitored settlement rate is 1.0 - 3.0 mm / d, the reserved spacing is increased to 1.5 m - 2.5 m; when the settlement rate is greater than 3.0 mm / d, no adjustment is made and the primary spraying concrete operation of the upper cycle described in the first step is carried out in a timely manner.

[0028] The beneficial effects of the present invention are as follows:

[0029] By making full use of the self-bearing capacity of the surrounding rock, the present invention reserves part of the working space, and effectively controls the external insertion angle of the peripheral holes by gradually replacing and lengthening the drill pipes, reducing the overbreak amount. At the same time, by taking the drill pipe angle in the peripheral reference holes as a reference, the drilling accuracy of the peripheral holes is improved, the phenomenon of overbreak and underbreak is reduced, and the stress concentration of the surrounding rock after blasting is effectively reduced. In addition, by setting the positions of the cut holes and the auxiliary holes respectively corresponding to the drilling of the cut holes and the auxiliary holes, the drilling accuracy is improved, the blasting effect is ensured, and powerful conditions are provided for finally realizing the designed smooth blasting. Through the above process, the goals of reducing overbreak, reducing the consumption of shotcrete and the operation time are achieved, the construction efficiency is improved, and the construction cost is reduced.

[0030] Other advantages, objectives and features of the present invention will be described to some extent in the subsequent description, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0032] Figure 1 is a schematic structural diagram before excavation of the present invention;

[0033] Figure 2 is a schematic structural diagram after excavation of the present invention;

[0034] Figure 3 is a schematic structural diagram of the layout of the peripheral holes, cut holes and auxiliary holes of the present invention;

[0035] Figure 4 is a schematic structural diagram at the position of the drill worker's standing position of the present invention;

[0036] Reference numerals: 1, surrounding rock surface; 2, excavation contour line; 3, cut hole position; 4, auxiliary hole position; 5, perimeter hole; 6, perimeter reference hole; 7, cut hole; 8, auxiliary hole; 9, reserved spacing; 10, driller's standing position. Detailed implementation manners

[0037] The present invention will be further described below in conjunction with the detailed implementation manners. Among them, the attached drawings are only for illustrative purposes, showing only schematic diagrams, rather than physical diagrams, and should not be construed as a limitation to this patent; in order to better illustrate the embodiments of the present invention, some components in the attached drawings will be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the attached drawings may be omitted. The diagrams provided in the following embodiments only illustrate the basic concept of the present invention schematically. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0038] In addition, the present invention may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or arrangements discussed.

[0039] As Figures 1 to 4 shown, a method for controlling overexcavation of tunnels suitable for intact surrounding rock mentioned in the present invention includes the following steps:

[0040] The first step is to spray concrete in the previous cycle initially,

[0041] After the blasting excavation and mucking for risk removal are completed, immediately apply the initial spray concrete in the initial support of the previous cycle to seal the surrounding rock surface 1 and reserve the reserved spacing 9 required for subsequent drilling operations;

[0042] The second step is to measure and set out the positions of the blast holes,

[0043] After the initial spray concrete in the first step is completed, the survey team accurately measures and sets out the excavation contour line 2, the cut hole position 3 and the auxiliary hole position 4 according to the blasting design;

[0044] The third step is the drilling operation of the perimeter holes 5,

[0045] The driller drills the perimeter holes 5 according to the measured positions of the perimeter holes at the excavation contour line 2;

[0046] First, drill the perimeter holes 5 at the positions of the crown and the two arch waists as the perimeter reference holes 6 for drilling the remaining perimeter holes 5 subsequently. The hole depth of the perimeter reference hole 6 is 1 m;

[0047] Then, starting from the three peripheral reference holes 6 at the vault and the two springing parts on both sides, the subsequent remaining peripheral holes 5 are drilled; specifically, the drilling of the remaining peripheral holes 5 is completed on both sides of the three peripheral reference holes 6 respectively. When drilling the remaining peripheral holes 5, the drill rod angle refers to the angle of the installed drill rod in the peripheral reference hole 6 it is close to.

[0048] Finally, for the drilling operations of the cut holes 7 at the cut hole positions 3 and the auxiliary holes 8 at the auxiliary hole positions 4, the intersection point of the extended drilling direction line and the designed drilling depth on the design drawing is used as the pre-positioned drill worker's standing position 10 in advance. The drill worker stands the drilling rig at the intersection point to perform the drilling operations for the cut holes 7 and the auxiliary holes 8.

[0049] Fourth step, charging and initiation,

[0050] Load the blasting materials according to the blasting design and connect the network for initiation.

[0051] Fifth step, removing hazards and mucking,

[0052] After blasting, after being checked by the blasting engineering technicians and found to be correct, mucking and hazard removal are carried out.

[0053] Sixth step, applying initial support,

[0054] Install the ring steel support and the wire mesh in the initial shotcrete of the previous cycle, and then re-spray the concrete to the designed thickness to achieve the initial shotcrete closure of the excavation surface of this cycle.

[0055] Seventh step, cyclic operation,

[0056] The above steps 1 to 6 are cycled. When the monitored measurement data changes greatly or the surrounding rock geological conditions deteriorate significantly, the reserved spacing 9 is adjusted. Specifically, according to the monitored measurement data, in this embodiment, when drilling the remaining peripheral holes 5, the drill rod angle refers to the angle of the installed drill rod in the peripheral reference hole 6 it is close to, ensuring that the peripheral holes are all on the same plane, effectively controlling the angle accuracy of the peripheral holes 5, improving the drilling accuracy of the peripheral holes 5, reducing the overbreak and underbreak, and reducing the stress concentration of the surrounding rock after blasting. The settings of the cut hole positions 3 and the auxiliary hole positions 4 improve the drilling accuracy of the cut holes 7 and the auxiliary holes 8 and ensure the blasting effect.

[0057] To control the external insertion angle of the peripheral holes 5 and reduce the overbreak amount, in the above embodiment, preferably: during the drilling operation of the peripheral holes 5, the drill rod is gradually replaced with a longer one for drilling.

[0058] To effectively control the accuracy of the external insertion angle of the peripheral holes 5, in the above embodiment, preferably: during the drilling operation of the peripheral holes 5, a 1m drill rod is used for the first drilling, and it is gradually replaced with 2m and 3m drill rods until the peripheral holes 5 are drilled and formed.

[0059] In order to include reserved space for subsequent drilling operations, reduce the outward inclination angle of peripheral holes, and reduce the overexcavation amount, in the above solution, further: the reserved spacing 9 in the seventh step is adjusted according to the monitoring and measurement data;

[0060] When the settlement rate of monitoring and measurement is 0.2 mm / d, the reserved spacing 9 is increased to 3.5 m - 4.5 m; when the settlement rate of monitoring and measurement is 0.2 - 1.0 mm / d, the reserved spacing 9 is increased to 2.5 m - 3.5 m; when the settlement rate of monitoring and measurement is 1.0 - 3.0 mm / d, the reserved spacing 9 is increased to 1.5 m - 2.5 m; when the settlement rate is greater than 3.0 mm / d, no adjustment is made and the initial shotcreting operation of the upper cycle described in the first step is carried out in a timely manner.

[0061] In the above implementation, the construction methods that are not explained are processed by using existing conventional technologies.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A method for controlling overexcavation in a tunnel with intact surrounding rock, characterized in that It includes the following steps: In the first step, perform the initial shotcrete for the upper cycle. After the blasting excavation and removal of dangerous rocks and muck are completed, immediately apply the initial shotcrete for the upper cycle in the initial support of the upper cycle to seal the surrounding rock surface (1) and reserve the reserved spacing (9) required for subsequent drilling operations. In the second step, conduct surveying and lofting to locate the positions of blast holes. After the initial shotcrete in the first step is completed, the surveying team accurately measures and marks the excavation contour line (2), the positions of cut holes (3), and the positions of auxiliary holes (4) according to the blasting design. In the third step, perform the drilling operation for the perimeter holes (5). The drillers drill the perimeter holes (5) according to the measured positions of the perimeter holes at the excavation contour line (2). First, drill the perimeter holes (5) at the crown and the two arch waists as the perimeter reference holes (6) for drilling the remaining perimeter holes (5). The depth of the perimeter reference holes (6) is 1 m. Then, start drilling the remaining perimeter holes (5) based on the three perimeter reference holes (6) at the crown and the two arch waists. Specifically, drill the remaining perimeter holes (5) on both sides of the three perimeter reference holes (6). When drilling the remaining perimeter holes (5), the drill rod angle refers to the installed drill rod angle in the adjacent perimeter reference hole (6). Finally, perform the drilling operations for the cut holes (7) at the positions of the cut hole points (3) and the auxiliary holes (8) at the positions of the auxiliary hole points (4). Advance the intersection point of the extended drilling direction line and the designed drilling depth on the design drawing as the advanced positioning position (10) for the drillers. The drillers stand the drilling rig at the intersection point to drill the cut holes (7) and the auxiliary holes (8). In the fourth step, charge and initiate the blast. Load the blasting materials according to the blasting design and connect the network for initiation. In the fifth step, remove dangerous rocks and muck. After blasting, after the blasting engineering and technical personnel check and confirm, remove the muck and dangerous rocks. In the sixth step, apply the initial support. Install the ring steel support and steel mesh in the initial shotcrete of the upper cycle and then re-spray the concrete to the designed thickness to achieve the initial shotcrete closure of the excavation surface of this cycle. In the seventh step, perform cyclic operations. Carry out cyclic operations according to the above steps 1 to 6. When the monitoring and measurement data change significantly or the surrounding rock geological conditions deteriorate significantly, adjust the reserved spacing (9).

2. The method for controlling over-excavation applicable to tunnels with intact surrounding rock according to claim 1, characterized in that, During the drilling operation of the perimeter holes (5), drill by gradually replacing the drill rods with longer lengths.

3. The method for controlling over-excavation applicable to tunnels with intact surrounding rock according to claim 2, wherein During the drilling operation of the perimeter holes (5), use 1-m drill rods for the first drilling and gradually replace them with 2-m and 3-m drill rods until the perimeter holes (5) are drilled and formed.

4. The over-excavation control method for tunnels in intact surrounding rock according to claim 1, characterized in that, In the seventh step, the adjustment of the reserved spacing (9) is based on the monitoring and measurement data. When the monitoring and measurement settlement rate is 0.2 mm / d, the reserved spacing (9) is increased to 3.5 m - 4.5 m; when the monitoring and measurement settlement rate is 0.2 - 1.0 mm / d, the reserved spacing (9) is increased to 2.5 m - 3.5 m; when the monitoring and measurement settlement rate is 1.0 - 3.0 mm / d, the reserved spacing (9) is increased to 1.5 m - 2.5 m; when the settlement rate is greater than 3.0 mm / d, no adjustment is made and immediately perform the upper cycle initial shotcrete operation described in the first step.

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