Synchronous excavation construction method for arc-shaped bottom plate of micro-step inverted arch

Abstract

The invention discloses a synchronous excavation construction method for a micro-step inverted arch arc-shaped bottom plate. The synchronous excavation construction method comprises the following steps that S1, blast holes are drilled in the tunnel face of a tunnel through a three-arm drill jumbo; s2, a slope is formed in the bottom area, close to the lower step face, of the excavated inverted arch filling body, and a plurality of obliquely-downward bottom holes are drilled in the position of the slope through a three-arm drill jumbo; s3, a plurality of obliquely downward pre-splitting blasting holes are drilled in the slope position; s4, the blasting holes, the bottom holes and the pre-splitting blasting holes are filled with explosives and connected, and then synchronous blasting is conducted; and S5, backfilling the primarily excavated inverted arch during deslagging after blasting, and properly rolling by using an excavator. The method has the advantages that the bottom hole and the presplitting blasting hole are formed in the position of the inverted arch to be excavated, so that full-section excavation of blasting the inverted arch along with the tunnel face can be realized, the blasting process is optimized, and the construction time is saved.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel excavation, and in particular relates to a synchronous excavation construction method for a micro-step inverted arch arc bottom plate. Background Art

[0002] In tunnel construction, the bench method involves excavating the upper tunnel section (the upper bench) first, then proceeding to the lower section (the lower bench) a certain distance ahead of the upper bench, with both steps excavated simultaneously. However, in existing construction methods, the inverted arch area is typically excavated by blasting at the face followed by a secondary manual drilling and blasting process. This makes the overall blasting process cumbersome and time-consuming. Furthermore, the secondary blasting of the inverted arch can cause vibrations to the completed primary support. Summary of the Invention

[0003] The object of the present invention is to provide a method for synchronous excavation of a micro-step inverted arch arc bottom plate in response to the above-mentioned deficiencies in the prior art. This method, by setting a bottom hole and a pre-splitting blasting hole at the position of the inverted arch to be excavated, can achieve full-section excavation of the inverted arch by blasting it together with the tunnel face, thereby optimizing the blasting process, saving construction time, and reducing the vibration impact of subsequent inverted arch blasting on the completed primary support. At the same time, the pre-splitting hole can pre-crush the corresponding part of the surrounding rock, facilitating subsequent mechanical excavation and reducing the workload of subsequent under-excavation.

[0004] The purpose of the present invention is achieved by the following technical solutions: A method for synchronous excavation of a micro-step inverted arched floor is applied to tunnel construction, wherein the tunnel face includes an upper step surface and a lower step surface. The method comprises the following steps: S1: using a three-arm drilling rig to drill blasting holes on the tunnel face and perform hole cleaning operations; S2: creating a slope in the area near the bottom of the lower step surface of the excavated inverted arch filling body, and using the three-arm drilling rig to drill a plurality of downwardly inclined bottom holes at the position of the slope, with each bottom hole having a different drilling depth and angle, and the bottom of each bottom hole being located on the same vertical section; the bottom of each bottom hole being higher than the preset arc-shaped arch bottom surface of the inverted arch to be excavated; S3: drilling a plurality of downwardly inclined pre-splitting blasting holes at the slope position; the bottom of each of the pre-splitting blasting holes is located on the preset arc-shaped arch bottom surface of the inverted arch to be excavated; S4: respectively charging and connecting the blasting hole, the bottom hole and the pre-splitting blasting hole, then evacuating the three-arm drilling rig and performing synchronous blasting; S5: After blasting, the inverted arch that has been initially excavated will be backfilled when the slag is discharged, and the excavator will be used to appropriately compact it; S6: Before the initial support of the invert arch is constructed, an excavator is used to excavate and remove slag from the invert arch. After the slag is removed, the blasting condition of the cross section is checked, and a breaker hammer is used to clear the under-excavated parts.

[0005] The bottom of each of the bottom holes is higher than the preset arc-shaped arch bottom surface of the inverted arch to be excavated, which means that a bottom plate with a thickness of 30 cm is reserved below the bottom of the bottom hole and is not excavated, and the bottom plate is located on the preset arc-shaped arch bottom surface of the inverted arch to be excavated.

[0006] The opening positions of the bottom eyes on the lower step surface are located on the same horizontal line and are arranged at intervals; the opening positions of the bottom eyes on the lower step surface are higher than the opening positions of the pre-splitting blasting holes on the lower step surface; the opening positions of the bottom eyes on the lower step surface are flush with the top surface of the excavated invert arch filling body.

[0007] The opening positions of the pre-splitting blasting holes on the lower step surface are located on the same horizontal line and are arranged at intervals; the opening positions of the pre-splitting blasting holes on the lower step surface are symmetrically arranged with respect to the perpendicular midline of the tunnel face.

[0008] The pre-splitting blasting holes include two rows, the bottoms of the pre-splitting blasting holes in the same row are located on the same section of the tunnel, and the sections where the bottoms of the pre-splitting blasting holes in different rows are located are spaced apart in the extending direction of the tunnel.

[0009] The advantages of the present invention are that, by arranging bottom holes and pre-splitting blasting holes at the position of the invert to be excavated, full-section excavation of the invert can be achieved by blasting the invert together with the tunnel face, thereby optimizing the blasting process, saving construction time, and reducing the vibration impact of subsequent invert blasting construction on the completed primary support. At the same time, the pre-splitting holes can pre-crush the corresponding part of the surrounding rock, which is convenient for subsequent mechanical excavation and loading, and reduces the workload of subsequent under-excavation processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Schematic diagram of the structure of the tunnel face in the present invention; Figure 2 It is a front view schematic diagram of the arrangement structure of the pre-splitting blasting holes in the present invention; Figure 3 A side view schematic diagram of the pre-splitting blasting hole arrangement structure of the present invention; like Figure 1-3 As shown in the figure, the marks are respectively represented as: upper step surface 11, lower step surface 12, excavated invert arch filling body 13, slope 21, bottom eye 22, and pre-splitting blasting hole 23. DETAILED DESCRIPTION

[0011] The features of the present invention and other related features are further described in detail below through embodiments in conjunction with the accompanying drawings to facilitate understanding by those skilled in the art: Example: Figure 1 、 2 As shown in FIG. 3 , this embodiment specifically relates to a synchronous excavation construction method for a micro-step inverted arch bottom plate, which is applied to tunnel construction. The tunnel face includes an upper step surface 11 and a lower step surface 12. The construction method includes the following steps: S1: A three-arm drilling rig is used to drill blasting holes and perform hole cleaning operations on the tunnel face. Drilling is performed from top to bottom, with three operators manipulating three robotic arms according to the designed hole positions displayed on the screen. After drilling to the designed depth, high-pressure water is used to flush debris from the hole. After the slot holes and footing holes in the middle and lower part of the tunnel face are completed, the charging rod is promptly inserted to the bottom of the hole to prevent vibration and collapse of the hole, which may result in the charging not reaching the bottom and affecting the slotting effect.

[0012] S2: As the construction progresses, the excavated inverted arch area has been filled to form an excavated inverted arch filling body 13. A slope 21 is provided in the portion of the excavated inverted arch filling body 13 close to the lower step surface 12 of the tunnel face. The slope 21 is gradually inclined downward toward the lower step surface 12. By providing the slope 21, it is convenient for a large drill bit used for drilling the bottom hole 22 and the pre-splitting blasting hole 23 to enter the hole and prevent blockage.

[0013] Using a three-arm drilling rig, several downward-sloping holes 22 are drilled on slope 21. Different drilling depths and angles are set based on the hole's offset from the tunnel, ensuring the bottoms of the holes are aligned on the same cross-section. A 30cm thick floor is left unexcavated at the bottom of the holes 22 to prevent overexcavation caused by drilling and blasting errors, as well as erosion and softening of the tunnel floor caused by water seepage.

[0014] S3: Pre-splitting blasting holes 23 are drilled in an arc-shaped triangular area. These holes are spaced at intervals of varying lengths and reach the tunnel bottom. The purpose of these holes is to pre-crush the surrounding rock, facilitating subsequent mechanical excavation and reducing the workload associated with underexcavation. The charge in these holes is adjusted based on the rock quality.

[0015] S4: Complete the charging and connection of the blasting hole, bottom hole 22 and pre-splitting blasting hole 23, then evacuate the three-arm drilling rig and carry out synchronous blasting.

[0016] S5: After blasting, the preliminarily excavated inverted arch is backfilled when the slag is discharged. The excavator is used to appropriately compact the inverted arch. After the preliminarily supported arch is completed, a slope 21 is left at the bottom of the micro-step before the next cycle excavation to facilitate the entry of the large machine drill bit into the hole and prevent blockage.

[0017] S6: Before the initial support of the invert arch is constructed, use an excavator to excavate the invert arch and remove the slag. After the slag is removed, check the cross-section blasting situation and use a breaker hammer to clear the under-excavated parts. If there are large unbroken hard rocks, carry out additional blasting.

[0018] like Figure 1 、 2 As shown in Figures 3 and 4, the bottom of each bottom hole 22 is a preset height higher than the preset curved bottom surface of the inverted arch to be excavated, while the bottom of each pre-splitting blasting hole 23 is located on the preset curved bottom surface of the inverted arch to be excavated. Both the bottom hole 22 and the pre-splitting blasting hole 23 are blastholes. The bottom of each bottom hole 22 is a preset height higher than the preset curved bottom surface of the inverted arch to be excavated. This allows a preset height of the floor plate to be reserved for the inverted arch, preventing over-excavation of the tunnel floor caused by drilling and blasting errors and erosion and softening of the tunnel floor by water seepage. The bottom of each pre-splitting blasting hole 23 is located on the preset curved bottom surface of the inverted arch to be excavated, reaching a depth that reaches the tunnel bottom. This allows for pre-crushing of the surrounding rock in this portion of the inverted arch, facilitating subsequent mechanical excavation and reducing the workload of subsequent under-excavation.

[0019] In some embodiments, the preset height is 30 cm, thereby reserving a 30 cm thick base plate for the inverted arch. Of course, the preset height can be adjusted according to actual construction requirements, and this embodiment does not make any specific limitation.

[0020] In some embodiments, the bottoms of the respective bottom holes 22 are optionally located on the same section of the tunnel. This allows accurate control of the blasting range of the respective bottom holes 22, i.e., the horizontal blasting length of the respective bottom holes 22 in the tunneling direction to be consistent.

[0021] Since the bottom surface of the inverted arch needs to be excavated in an arc shape, the bottom holes 22 need to be set with different drilling depths and angles according to the offset of the tunnel in which they are located, so that the bottoms of the bottom holes 22 are all located on the same section of the tunnel.

[0022] In other embodiments, optionally, the opening positions of the bottom holes 22 on the lower step surface 12 are located on the same horizontal line and are arranged at intervals to facilitate the control of the excavation angle and excavation depth of the bottom holes 22.

[0023] In this embodiment, for example, the opening position of the bottom eye 22 on the lower step surface 12 is flush with the top surface of the excavated inverted arch filling body 13, that is, the bottom eye 22 is drilled obliquely downward at the horizon position of the arch foot, so as to control the blasting area of the bottom eye 22 to be the inverted arch area to be excavated.

[0024] In some embodiments, the opening positions of the pre-splitting blasting holes 23 on the lower step surface 12 are located on the same horizontal line and are spaced apart. Optionally, the opening positions of the pre-splitting blasting holes 23 on the lower step surface 12 are symmetrically arranged about the mid-perpendicular line of the tunnel face. The spaced and symmetrical arrangement of the pre-splitting blasting holes 23 allows for uniform blasting of the surrounding rock in the invert area to be excavated, facilitating subsequent mechanical excavation of the invert.

[0025] In this embodiment, pre-splitting blasting holes 23 may optionally be provided in two rows. The bottoms of the pre-splitting blasting holes 23 in the same row are located on the same cross-section of the tunnel, and the cross-sections of the bottoms of the pre-splitting blasting holes 23 in different rows are spaced apart in the tunnel's extension direction. Providing two rows of pre-splitting blasting holes 23 allows for uniform and effective pre-crushing of the surrounding rock, facilitating subsequent mechanical excavation and reducing the workload associated with underexcavation.

[0026] In some embodiments, the bottom hole 22 can optionally be positioned higher on the lower step surface 12 than the pre-splitting blasting hole 23. Thus, the bottom hole 22 and the pre-splitting blasting hole 23 can be located at different locations within the invert to be excavated, achieving efficient blasting. The distance between the tunnel cross-section where the bottom of the pre-splitting blasting hole 23 lies and the lower step surface 12 is smaller than the distance between the tunnel cross-section where the bottom of the bottom hole 22 lies and the lower step surface 12. This means that the bottom hole 22 is used for blasting the entire section of the invert to be excavated, while the pre-splitting blasting hole 23 is primarily used for pre-crushing the surrounding rock within the entire section of the invert to be excavated.

[0027] The beneficial effects of this embodiment are as follows: by setting bottom holes and pre-splitting blasting holes at the position of the invert to be excavated, full-section excavation of the invert can be achieved by blasting the invert together with the tunnel face, reducing the subsequent secondary manual drilling and blasting construction of the invert, optimizing the blasting process, and saving construction time; at the same time, the vibration effect of the subsequent blasting of the invert on the completed primary support is weakened, and the deformation of the primary support is reduced; further, it can also avoid the damage of the invert trestle, side wall waterproofing board and other machinery and entities caused by flying rocks during the blasting of the invert, thereby reducing the difficulty of cleaning; in addition, the pre-splitting holes can pre-crush the corresponding part of the surrounding rock, which is convenient for subsequent mechanical excavation and loading, and reduces the workload of processing the subsequent under-excavation.

Claims

1. A method for synchronous excavation of a micro-step inverted arch bottom plate, applied to tunnel construction, wherein the tunnel face includes an upper step surface and a lower step surface, characterized in that The construction method comprises the following steps: S1: using a three-arm drilling rig to drill blasting holes on the tunnel face and perform hole cleaning operations; S2: creating a slope in the area near the bottom of the lower step surface of the excavated inverted arch filling body, and using the three-arm drilling rig to drill a plurality of downwardly inclined bottom holes at the position of the slope, with each bottom hole having a different drilling depth and angle, and the bottom of each bottom hole being located on the same vertical section; the bottom of each bottom hole being higher than the preset arc-shaped arch bottom surface of the inverted arch to be excavated; S3: drilling a plurality of downwardly inclined pre-splitting blasting holes at the slope position; the bottom of each of the pre-splitting blasting holes is located on the preset arc-shaped arch bottom surface of the inverted arch to be excavated; S4: respectively charging and connecting the blasting hole, the bottom hole and the pre-splitting blasting hole, then evacuating the three-arm drilling rig and performing synchronous blasting; S5: After blasting, the inverted arch that has been initially excavated will be backfilled when the slag is discharged, and the excavator will be used to appropriately compact it; S6: Before the initial support of the invert arch is constructed, an excavator is used to excavate and remove slag from the invert arch. After the slag is removed, the blasting condition of the cross section is checked, and a breaker hammer is used to clear the under-excavated parts.

2. The synchronous excavation construction method for a micro-step inverted arch bottom plate according to claim 1 is characterized in that The bottom of each of the bottom holes is higher than the preset arc-shaped arch bottom surface of the inverted arch to be excavated, which means that a bottom plate with a thickness of 30 cm is reserved below the bottom of the bottom hole and is not excavated, and the bottom plate is located on the preset arc-shaped arch bottom surface of the inverted arch to be excavated.

3. The synchronous excavation construction method for a micro-step inverted arch bottom plate according to claim 1 is characterized in that The opening positions of the bottom eyes on the lower step surface are located on the same horizontal line and are arranged at intervals; the opening positions of the bottom eyes on the lower step surface are higher than the opening positions of the pre-splitting blasting holes on the lower step surface; the opening positions of the bottom eyes on the lower step surface are flush with the top surface of the excavated invert arch filling body.

4. The synchronous excavation construction method for a micro-step inverted arch bottom plate according to claim 1 is characterized in that The opening positions of the pre-splitting blasting holes on the lower step surface are located on the same horizontal line and are arranged at intervals; the opening positions of the pre-splitting blasting holes on the lower step surface are symmetrically arranged with respect to the perpendicular midline of the tunnel face.

5. The synchronous excavation construction method for a micro-step inverted arch bottom plate according to claim 4 is characterized in that The pre-splitting blasting holes include two rows, the bottoms of the pre-splitting blasting holes in the same row are located on the same section of the tunnel, and the sections where the bottoms of the pre-splitting blasting holes in different rows are located are spaced apart in the extending direction of the tunnel.

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