Three-step method reserved core soil drilling and blasting construction method

Abstract

The application discloses a three-step method for reserving core soil drilling and blasting construction method, which comprises the following steps: using an excavator to excavate an arc-shaped guide pit in the upper part of a tunnel section to form a core soil layer and a spring soil layer in the upper part of the tunnel section; drilling and blasting excavation is performed on the spring soil layer to remove the spring soil layer; the core soil layer is removed by using the excavator to form an upper step; a middle step is excavated in the middle part of the tunnel section by using the excavator; and a lower step is excavated in the lower part of the tunnel section by using the excavator. The scheme changes the traditional excavation method, adopts an excavation method combining blasting and mechanical excavation, can effectively reduce the disturbance of rock mass in the tunnel construction process, greatly reduces the risk of falling and collapse of the working face caused by large disturbance, provides a safer working environment for the construction of the next process, and reduces the large initial support settlement deformation caused by large disturbance of the rock mass.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, specifically to a three-stage method for pre-reserved core soil drilling and blasting construction. Background Technology

[0002] The tunnel traverses an area with extremely high ground stress. The surrounding rock in this area is loose, fractured, and has well-developed joints and fissures. It is mostly reddish-brown argillaceous sandstone, which is relatively soft. When excavating the tunnel in this area, the rock mass is disturbed, making it prone to overall subsidence and landslides. Summary of the Invention

[0003] The main objective of this invention is to propose a three-stage method for pre-reserved core soil drilling and blasting construction, which aims to solve the problem that when excavating tunnels in areas with extremely high ground stress, the rock mass is disturbed, and the overall subsidence and collapse are likely to occur.

[0004] To achieve the above objectives, this invention proposes a three-stage method for pre-reserved core soil drilling and blasting construction, comprising the following steps:

[0005] An excavator is used to excavate an arc-shaped pilot tunnel in the upper part of the tunnel cross-section to form a core soil layer and an arch foot soil layer in the upper part of the tunnel cross-section.

[0006] The soil layer at the arch foot was excavated by drilling and blasting to remove it.

[0007] The core soil layer was excavated and removed using an excavator to form an upper step;

[0008] An excavator was used to excavate a middle bench in the middle of the tunnel cross-section;

[0009] An excavator was used to excavate a lower step at the bottom of the tunnel cross-section.

[0010] Optionally, the step of drilling and blasting to remove the arch foot soil layer includes:

[0011] Obtain the span and height of the arc-shaped guide pit, and determine the location of the blast holes for drilling and blasting excavation based on the span and height;

[0012] Obtain the soil quality of the tunnel cross-section and determine the number of blast holes to be drilled and blasted based on the soil quality.

[0013] The arch foot soil layer is excavated by drilling and blasting based on the location and number of blast holes.

[0014] Optionally, the step of obtaining the span and height of the arc-shaped pilot tunnel, and determining the location of the blast holes for drill-and-blast excavation based on the span and height, includes:

[0015] Calculate the ratio of the span to the height, and determine the location of the blast holes for drilling and blasting based on the ratio.

[0016] Optionally, the step of calculating the ratio of the span to the height and determining the location of the blast holes for drilling and blasting excavation based on the ratio includes:

[0017] When the ratio is greater than or equal to 4, the distance between the blast hole location and the upper step line of the tunnel cross section is 1 to 2 mm;

[0018] When the ratio is less than 4, the distance between the blast hole location and the upper step line of the tunnel cross section is 0.8 to 0.9 mm.

[0019] Optionally, the step of obtaining the soil quality of the tunnel cross-section and determining the number of blast holes for drilling and blasting excavation based on the soil quality includes:

[0020] When the soil quality is grade I to IV, the number of blast holes is 1 to 2;

[0021] When the soil quality is grade V to VI, the number of blast holes is 3 to 4.

[0022] Optionally, in the step of drilling and blasting to remove the soil layer at the arch foot:

[0023] The drilling and blasting excavation is carried out using a drilling device, which includes an outer sleeve and a drilling shaft disposed inside the outer sleeve. The drilling shaft is detachably connected to the outer sleeve.

[0024] Optionally, the step of drilling and blasting to remove the arch foot soil layer includes:

[0025] Insert the outer sleeve into the arch foot soil layer and push the drill shaft along the axial direction of the outer sleeve to drill blast holes in the arch foot soil layer;

[0026] Remove the drill shaft from the outer sleeve, fill the outer sleeve and the blast hole with explosives, and detonate to excavate.

[0027] Optionally, after the step of using an excavator to excavate an arc-shaped pilot tunnel in the upper part of the tunnel cross-section to form a core soil layer and an arch foot soil layer in the upper part of the tunnel cross-section, the method further includes:

[0028] Initial support for the arch of the arc-shaped guide pit is installed.

[0029] Optionally, after the step of excavating a middle bench in the middle of the tunnel cross-section using an excavator, the method further includes:

[0030] Initial support for the sidewalls is installed on the middle step.

[0031] Optionally, after the step of excavating a lower step at the bottom of the tunnel cross-section using an excavator, the method further includes:

[0032] Initial support for the invert arch was installed on the lower step.

[0033] In the technical solution of this invention, an excavator is first used to excavate an arc-shaped pilot tunnel in the upper part of the tunnel cross-section to form a core soil layer and an arch foot soil layer in the upper part of the tunnel cross-section. Then, the arch foot soil layer is removed by drilling and blasting. Next, the excavator is used to excavate and remove the core soil layer to form an upper step. After that, an excavator is used to excavate a middle step in the middle of the tunnel cross-section. Finally, an excavator is used to excavate a lower step in the lower part of the tunnel cross-section. This solution changes the traditional excavation method and adopts an excavation method that combines blasting and mechanical excavation. During tunnel construction, it can effectively reduce the disturbance of the rock mass, thereby greatly reducing the risk of rockfall and collapse at the tunnel face caused by large disturbances. This provides a safer working environment for subsequent construction processes and reduces the phenomenon of large initial support settlement and deformation caused by large disturbances of the rock mass. Attached Figure Description

[0034] 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.

[0035] Figure 1 A flowchart illustrating an embodiment of the three-step method for pre-reserved core soil drilling and blasting construction provided by the present invention;

[0036] Figure 2 This is a diagram showing the layout of blast holes for the three-step method of pre-reserved core soil drilling and blasting construction of the present invention.

[0037] Explanation of icon numbers:

[0038] label name label name 1 blast-hole 4 Climbing the steps 2 core soil layer 5 Middle steps 3 Arch foot soil layer 6 Go down the steps

[0039] The realization of the objective of this invention, its functional characteristics and excellent effects will be further explained below in conjunction with specific embodiments and accompanying drawings. Detailed Implementation

[0040] 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.

[0041] It should be noted that if the embodiments of the present invention involve directional indication, the directional indication is only used to explain the relative positional relationship and movement of the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0042] 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. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, 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. If 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.

[0043] The tunnel traverses an area with extremely high ground stress. The surrounding rock in this area is loose, fractured, and has well-developed joints and fissures. It is mostly reddish-brown argillaceous sandstone, which is relatively soft. When excavating the tunnel in this area, the rock mass is disturbed, making it prone to overall subsidence and landslides.

[0044] In view of this, the present invention provides a three-stage method for pre-reserved core soil drilling and blasting construction. Figure 1 This is a flowchart illustrating an embodiment of the three-stage method for pre-reserved core soil drilling and blasting construction provided by the present invention. Figure 2 This is a diagram showing the layout of blast holes for the three-step method of pre-reserved core soil drilling and blasting construction of the present invention.

[0045] Please refer to Figure 1 The three-step method for pre-reserved core soil drilling and blasting construction includes the following steps:

[0046] Step S10: Use an excavator to excavate an arc-shaped pilot tunnel in the upper part of the tunnel cross-section to form a core soil layer and an arch foot soil layer in the upper part of the tunnel cross-section.

[0047] Step S20: Drill and blast excavation is carried out on the arch foot soil layer to remove the arch foot soil layer.

[0048] Step S30: Use an excavator to excavate and remove the core soil layer to form an upper step.

[0049] Step S40: Use an excavator to excavate a middle bench in the middle of the tunnel cross section.

[0050] Step S50: Use an excavator to excavate a lower step at the bottom of the tunnel cross section.

[0051] In the technical solution of this invention, an excavator is first used to excavate an arc-shaped pilot tunnel in the upper part of the tunnel cross-section to form a core soil layer 2 and an arch foot soil layer 3 in the upper part of the tunnel cross-section. Then, the arch foot soil layer 3 is excavated by drilling and blasting (see details). Figure 2 The process involves removing the arch foot soil layer 3, then using an excavator to excavate and remove the core soil layer 2 to form an upper step 4. Next, an excavator is used to excavate a middle step 5 in the middle of the tunnel cross-section, and finally, an excavator is used to excavate a lower step 6 at the bottom of the tunnel cross-section. This method, by changing the traditional excavation method, adopts a combination of blasting and mechanical excavation. This effectively reduces rock mass disturbance during tunnel construction, significantly lowering the risk of rockfall and collapse at the tunnel face due to large disturbances. It provides a safer working environment for subsequent construction processes and reduces the large initial support settlement and deformation caused by significant rock mass disturbance.

[0052] Specifically, step S10 includes:

[0053] Step S11: Obtain the span and height of the arc-shaped guide pit, and determine the location of the blast holes for drilling and blasting excavation based on the span and height.

[0054] Step S12: Obtain the soil quality of the tunnel cross section and determine the number of blast holes to be drilled and blasted based on the soil quality.

[0055] Step S13: Drill and blast excavate the soil layer at the arch foot according to the location and number of blast holes.

[0056] In this scheme, the location of the blast hole 1 for drilling and blasting is first determined according to the span and height of the arc-shaped guide tunnel, and then the number of blast holes 1 for drilling and blasting is determined according to the soil quality of the tunnel section. The obtained location and number of blast holes 1 are reasonable, which can avoid excessive disturbance of the surrounding rock mass during drilling and blasting, causing the initial support to sink and the rock mass to collapse.

[0057] Specifically, step S11 includes:

[0058] Step S111: Calculate the ratio of the span to the height, and determine the location of the blast holes for drilling and blasting based on the ratio.

[0059] In this scheme, the ratio of the span to the height is first calculated, and then the position of the blast hole 1 for drilling and blasting is determined according to the ratio. Different ratios of the span to the height correspond to different arch angles of the arc-shaped guide pit. In this way, the final determined position of the blast hole 1 matches the arch angle of the arc-shaped guide pit, avoiding the blast hole 1 position being too high and causing the surrounding rock mass to collapse.

[0060] Specifically, step S111 includes:

[0061] Step S111a: When the ratio is greater than or equal to 4, the distance between the blast hole location and the upper step line of the tunnel cross section is 1 to 2 mm.

[0062] Step S111b: When the ratio is less than 4, the distance between the blast hole location and the upper step line of the tunnel cross section is 0.8 to 0.9 mm.

[0063] In this scheme, when the ratio is greater than or equal to 4, the distance between the location of the blast hole 1 and the upper step 4 line of the tunnel cross section is 1 to 2 mm. When the ratio is less than 4, the distance between the location of the blast hole 1 and the upper step 4 line of the tunnel cross section is 0.8 to 0.9 mm. Thus, the determined height of the blast hole 1 is reasonable, which greatly reduces the risk of surrounding rock collapse.

[0064] Specifically, step S12 includes:

[0065] Step S121: When the soil quality is grade I to IV, the number of blast holes is 1 to 2.

[0066] Step S122: When the soil quality is grade V to VI, the number of blast holes is 3 to 4.

[0067] The higher the soil grade, the more solid the soil, and the less difficult it is to blast and excavate. Therefore, in this scheme, when the soil grade is I to IV, the number of blast holes 1 is 3 to 4, and when the soil grade is V to VI, the number of blast holes 1 is 1 to 2. In this way, the more solid the soil, the more blast holes 1 there are, making the blasting more effective and ensuring that the arch foot soil layer 3 is completely removed.

[0068] Specifically, in step S13: during the drill-and-blast excavation, a drilling device is used to drill holes. The drilling device includes an outer sleeve and a drilling shaft disposed within the outer sleeve, and the drilling shaft is detachably connected to the outer sleeve. Thus, the drilling device consists of an outer sleeve and a drilling shaft, which has a simple structure and is easy to use.

[0069] Specifically, step S13 includes:

[0070] Step S131: Insert the outer sleeve into the arch foot soil layer and push the drill shaft along the axial direction of the outer sleeve to drill blast holes in the arch foot soil layer.

[0071] Step S132: Remove the drill shaft from the outer sleeve, fill the outer sleeve and the blast hole with explosives, and detonate to excavate.

[0072] In this scheme, the drilling shaft and the outer sleeve are detachably connected. After drilling is completed, the drilling shaft can be removed for secondary recycling; while the outer sleeve remains in the arch foot soil layer 3, effectively maintaining the stability of the drilled blast hole 1 and improving the blasting excavation effect.

[0073] Following step S10, the method further includes:

[0074] Step S60: Install the initial support for the arch of the guide tunnel in the arc-shaped guide tunnel.

[0075] In this scheme, by installing the initial support of the arch of the arc-shaped pilot tunnel, the initial support of the arc-shaped pilot tunnel is formed, which avoids the rock mass from sinking and facilitates the subsequent excavation of the upper step 4.

[0076] Following step S40, the following is also included:

[0077] Step S70: Install initial support for the sidewalls on the middle step.

[0078] In this scheme, by installing initial support walls on the middle step 5, the middle step 5 is initially supported to prevent rock mass subsidence and facilitate the subsequent excavation of the lower step 6.

[0079] Following step S50, the following is also included:

[0080] Step S80: Install the initial support for the invert arch on the lower step.

[0081] In this scheme, by installing an inverted arch initial support on the lower step 6, the lower step 6 is provided with initial support to prevent rock mass subsidence and facilitate subsequent tunnel excavation.

[0082] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure made using the contents of the present invention specification and drawings, or directly or indirectly applied to other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A three-stage method for pre-reserved core soil drilling and blasting construction, characterized in that, Includes the following steps: An excavator is used to excavate an arc-shaped pilot tunnel in the upper part of the tunnel cross-section to form a core soil layer and an arch foot soil layer in the upper part of the tunnel cross-section. The soil layer at the arch foot was excavated by drilling and blasting to remove it. The core soil layer was excavated and removed using an excavator to form an upper step; An excavator was used to excavate a middle bench in the middle of the tunnel cross-section; Use an excavator to excavate a lower step at the bottom of the tunnel cross section; The step of drilling and blasting to remove the soil layer at the arch foot includes: Obtain the span and height of the arc-shaped guide pit, and determine the location of the blast holes for drilling and blasting excavation based on the span and height; Obtain the soil quality of the tunnel cross section and determine the number of blast holes for drilling and blasting based on the soil quality. The arch foot soil layer is drilled and blasted excavated according to the location and number of blast holes. In the step of drilling and blasting to remove the soil layer at the arch foot: The drilling and blasting excavation is carried out using a drilling device, which includes an outer sleeve and a drilling shaft disposed inside the outer sleeve. The drilling shaft is detachably connected to the outer sleeve. Insert the outer sleeve into the arch foot soil layer and push the drill shaft along the axial direction of the outer sleeve to drill blast holes in the arch foot soil layer; Remove the drill shaft from the outer sleeve, fill the outer sleeve and the blast hole with explosives, and detonate to excavate; The step of obtaining the span and height of the arc-shaped guide pit, and determining the location of the blast holes for drilling and blasting excavation based on the span and height, includes: Calculate the ratio of the span to the height, and determine the location of the blast holes for drilling and blasting based on the ratio; The step of calculating the ratio of the span to the height, and determining the location of the blast holes for drilling and blasting excavation based on the ratio, includes: When the ratio is greater than or equal to 4, the distance between the blast hole location and the upper step line of the tunnel cross section is 1~2mm; When the ratio is less than 4, the distance between the blast hole location and the upper step line of the tunnel cross section is 0.8~0.9mm.

2. The three-stage method for pre-reserved core soil drilling and blasting construction as described in claim 1, characterized in that, The steps of obtaining the soil quality of the tunnel cross-section and determining the number of blast holes for drilling and blasting excavation based on the soil quality include: When the soil quality is grade I to IV, the number of blast holes is 1 to 2; When the soil quality is grade V to VI, the number of blast holes is 3 to 4.

3. The three-stage method for pre-reserved core soil drilling and blasting construction as described in claim 1, characterized in that, Following the step of using an excavator to excavate an arc-shaped pilot tunnel in the upper part of the tunnel cross-section to form a core soil layer and an arch foot soil layer in the upper part of the tunnel cross-section, the method further includes: Initial support for the arch of the arc-shaped guide pit is installed.

4. The three-stage method for pre-reserved core soil drilling and blasting construction as described in claim 1, characterized in that, Following the step of excavating a middle bench in the middle of the tunnel cross-section using an excavator, the method further includes: Initial support for the sidewalls was installed on the middle step.

5. The three-stage method for pre-reserved core soil drilling and blasting construction as described in claim 1, characterized in that, Following the step of excavating a lower step at the bottom of the tunnel cross-section using an excavator, the method further includes: Initial support for the invert arch was installed on the lower step.

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