Chamber overexcavation support construction method

Abstract

The invention provides a chamber overexcavation support construction method. The construction method comprises the steps that the steel arch is built along the rock wall of the chamber; according to the geological conditions of the chamber and the over-excavation area above the steel arch, the arrangement position of a filling component is determined; measuring a radial distance at the position where the filling member is disposed; selecting an air bag and glass fiber cloth; coating epoxy resin on the surface of the glass fiber cloth; winding multiple layers of glass fiber cloth on the surface of the airbag; placing an air bag in the gap; the air bag is inflated to expand to drive the multiple layers of glass fiber cloth wound on the surface to slide between layers; when the glass fiber cloth is tightly attached to the surrounding rock, inflation is stopped, and air pressure in the air bag is maintained; after being cured, the epoxy resin and the glass fiber cloth form a closed annular filling component; and the air bag and the filling component are separated and taken out, and the filling component is reserved in the gap to form over-excavation area local support. The problems that due to chamber over-excavation, surrounding rock above a steel arch is suspended, and a supporting structure and the surrounding rock cannot form effective contact supporting are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel engineering support, and particularly relates to a chamber overbreak support construction method. BACKGROUND

[0002] The drill-and-blast method has been widely used in tunnel excavation due to its mature technology, relatively low cost, and the ability to form chambers of different shapes and sizes. However, in actual construction practice, it is found that there is a significant engineering contradiction between the drilling speed and the precision of the blast forming: if the drilling efficiency is pursued unilaterally, the precision of the blast forming will be greatly reduced, resulting in serious overbreak of the chamber cross-section profile. Statistics show that when the overbreak exceeds 15% of the designed cross-sectional area, a 20-50 cm gap will be formed between the steel arch and the surrounding rock, making it impossible for the support structure to form effective contact and support with the surrounding rock. In the prior art, the overbreak phenomenon is usually handled by backfilling concrete in the gap above the steel arch.

[0003] For example, a concrete filling device for roadway steel support disclosed in the existing patent publication CN111502702A has an air bag above the steel arch for closing the gap between the steel arch and the surrounding rock. A plurality of grouting holes are provided on the air bag, and concrete is injected into the grouting area through the grouting holes. After the concrete is set, the air bag is deflated and removed, and the concrete filling in the gap between the steel arch and the surrounding rock is completed. This method can ensure that the overbreak gap between the steel arch and the surrounding rock is effectively filled with concrete, solving the problem of the support structure failing to form effective contact and support with the surrounding rock. However, the concrete grouting operation has a long construction period, requires a large amount of materials for support, and the filled concrete is prone to cracking and chipping during the chamber support period.

[0004] For example, a roadway support structure and method disclosed in the existing patent publication CN109578012A uses a steel arch and an air bag arranged along the surface of the surrounding rock for surrounding rock support. The air bag can fill the gap between the steel arch and the surrounding rock after inflation. Although this method effectively fills the chamber overbreak gap with the inflated air bag, the air bag has a large deformation and low stiffness, and cannot withstand a large amount of surrounding rock pressure, so it cannot constrain the deformation of the surrounding rock, which can lead to support failure. In addition, the air bag directly contacts the overbreak area of the surrounding rock after inflation, and the rock mass can rub against the surface of the air bag, causing the local thickness of the air bag to thin, resulting in uneven air pressure, reduced air tightness, and support failure. SUMMARY

[0005] The present application aims to provide a chamber overbreak support construction method suitable for rapid temporary support of the chamber overbreak area.

[0006] The technical solution of the present application is a chamber overbreak support construction method, comprising: Step one, install steel arch along the rock wall of the chamber, the steel arch is installed along the chamber longitudinal interval multiple; Step two, according to the chamber geological conditions and the overbreak area above the steel arch, determine the setting position of the filling member; measure the radial distance of the gap between the surrounding rock and the steel arch at the setting position of the filling member; Step three, according to the radial distance measured in step two, select the air bag and glass fiber cloth; apply the mixed epoxy resin on the surface of the glass fiber cloth; Step four, wrap multiple layers of glass fiber cloth coated with epoxy resin on the outer surface of the air bag; Step five, place the air bag of step four in the gap between the surrounding rock and the steel arch of the overbreak area at the corresponding position; Step six, inflate the air bag to make it expand, and drive the interlayer slip of the multiple layers of glass fiber cloth wrapped on its surface; when the glass fiber cloth is in close contact with the surrounding rock, stop inflating the air bag and maintain the air pressure in the air bag; Step seven, maintain the air pressure in the air bag for a period of time, so that the epoxy resin solidifies to form a closed ring-shaped resin-based glass fiber filling member together with the glass fiber cloth; Step eight, release the gas in the air bag to separate the air bag from the filling member, take out the air bag, and the filling member remains in the gap between the steel arch and the surrounding rock of the overbreak area to form a local support for the overbreak area.

[0007] In the above scheme, the resin-based glass fiber member with higher toughness than the air bag is used to fill the overbreak gap, which can avoid problems such as local wear of the air bag, uneven air pressure, and support failure, and the air bag can be quickly (about 0.5 hours) recycled and reused, which is more suitable for quick temporary support of the overbreak area of the chamber.

[0008] Preferably, when the air bag is selected, its diameter before expansion is less than the radial distance of the gap between the surrounding rock and the steel arch of the overbreak area, so that the air bag can be placed in the gap after winding the glass fiber cloth.

[0009] Preferably, the expanded air bag makes the glass fiber cloth wrapped on its surface closely contact with the irregular surface of the surrounding rock of the overbreak area.

[0010] Preferably, in step six, the air pressure in the air bag is maintained for 10-20 minutes.

[0011] Preferably, in step three, the length of the glass fiber cloth is at least six times the measured radial distance, and the width of the glass fiber cloth is greater than the width of the steel arch and less than the length of the air bag.

[0012] Preferably, the epoxy resin is an A / B component resin, which can interlayer slip with the glass fiber cloth before curing; the curing time of the epoxy resin is 20-40 minutes. Preferably, the glass fiber cloth can absorb epoxy resin, and after the epoxy resin is cured, the glass fiber cloth forms a filling member capable of bearing the surrounding rock pressure and resisting the deformation of the surrounding rock.

[0013] Preferably, in step four, a rubber band is used to temporarily fix the glass fiber cloth wrapped outside the air bag.

[0014] Preferably, in step five, the air bag is connected to an air compressor through a hose; and in step six, the air compressor is started to inflate the air bag.

[0015] Preferably, the chamber overbreak support construction method further comprises step nine, repeating the above steps two to eight in other overbreak areas above the steel arch, until the support of the chamber overbreak free area is completed.

[0016] Compared with the related art, the present application has the following advantages: First, the present application effectively transmits the surrounding rock pressure to the steel arch through the filling member, solving the problem that the surrounding rock above the steel arch is suspended due to the chamber overbreak, and the support structure cannot form effective contact and support with the surrounding rock; Second, the resin-based glass fiber support structure used in the present application has high strength, good rigidity, easy-to-ensure construction quality, short resin curing time, and high construction operation efficiency, which can effectively realize rapid and effective support of the chamber overbreak area at local positions and accurate points; Third, the present application uses epoxy resin to coat the glass fiber cloth, and then winds the glass fiber cloth around the surface of the air bag. In the process of inflation and expansion of the air bag, the glass fiber cloth wound on the surface of the air bag is stretched and expanded, interlayer sliding occurs, and the internal gas pressure is maintained for a period of time, which provides support for the glass fiber cloth wound on the surface of the air bag. After the epoxy resin is cured to form an irregular cylindrical resin-based glass fiber filling member, the gas in the air bag can be released, and the air bag can be reused. The air bag has a short service life and high reusability, which can quickly and efficiently complete the support construction in a short time, effectively reducing the support cost; Fourth, the resin-based glass fiber filling member in the present application belongs to a filling member that can be quickly constructed. In the initial stage of chamber excavation, the stress release and deformation of the surrounding rock are large, and the support of the chamber overbreak area can be quickly completed. During the support period, the member can bear a large surrounding rock pressure and resist the deformation of the surrounding rock, which maximizes the self-supporting capacity of the chamber surrounding rock, improves the support quality, and ensures the stability of the support system; Fifth, unlike the prior art in which the air bag directly contacts and supports the surrounding rock, the present application uses a resin-based glass fiber member with higher toughness than the air bag to fill the overbreak gap, avoiding problems such as local wear of the air bag, uneven air pressure, and support failure. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A schematic diagram of setting up a steel arch in a chamber; Figure 2 A schematic diagram of cutting a glass fiber cloth; Figure 3 A schematic diagram of applying epoxy resin on the surface of the glass fiber cloth; Figure 4 A schematic diagram of winding the glass fiber cloth on the surface of the air bag; Figure 5 A schematic diagram of installing the filling member; Figure 6 A schematic diagram of making the glass fiber cloth on the surface of the inflated air bag interlayer slip; Figure 7 A schematic diagram of the overall support after construction; Figure 8 A flow chart of the chamber overbreak support construction method provided by the present application.

[0018] In the drawings: 1, steel arch; 2, surrounding rock; 3, air bag; 4, glass fiber cloth; 5, rubber band; 6, epoxy resin; 7, hose; 8, air compressor; 9, filling member. DETAILED DESCRIPTION

[0019] The present application will be described in detail below with reference to the drawings and in conjunction with embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. For the convenience of description, if the words "up", "down", "left", "right" appear in the following text, they only mean consistent with the up, down, left and right directions of the drawings themselves, and do not limit the structure.

[0020] As shown in Figure 8 , the chamber overbreak support construction method provided by the present embodiment includes the following steps: S1, as shown in Figure 1 , a plurality of steel arches 1 are set up along the longitudinal direction of the chamber, and the steel arches 1 are adjusted to be as close as possible to the rock wall of the surrounding rock 2.

[0021] S2, the setting position of the filling member 9 (i.e. the position that needs to be supported) is determined according to the geological conditions of the chamber and the size of the overbreak area above the steel arch 1. The radial distance of the gap between the surrounding rock 2 and the steel arch 1 at the position that needs to be supported is measured.

[0022] S3, select the air bag 3 and the glass fiber cloth 4 according to the measured radial distance. The air bag 3 is made of rubber material, which has good inflation function, surface deformation performance and gas sealing performance, can meet the diameter expansion several times after filling high pressure gas, can ensure that the glass fiber cloth 4 wrapped on the surface of the air bag after inflation can be closely attached to the surface of the irregular over-excavation area of the surrounding rock, and can maintain the internal gas pressure after stopping the internal inflation. The diameter of the air bag 3 before inflation is smaller than the radial distance of the gap between the over-excavation area surrounding rock 2 and the steel arch 1, so that it can be put into the gap after winding the glass fiber cloth 4.

[0023] The glass fiber cloth 4 is rectangular, and the length is at least six times the measured radial distance of the gap. The width of the glass fiber cloth 4 is greater than the width of the steel arch 1 and less than the length of the air bag 3. The length of the glass fiber cloth 4 is determined by the geological conditions of the over-excavation area above the steel arch 1 and the radial distance of the over-excavation area. The length of the glass fiber cloth 4 needs to ensure that after the air bag 3 inflates, although the multiple layers of glass fiber cloth 4 wrapped on the surface of the air bag 3 have interlayer slip, the glass fiber cloth 4 can still form a closed ring after the air bag 3 inflates. If the regional geological conditions are poor, the number of layers of the glass fiber cloth 4 can be increased to adjust the winding to ensure that the formed filling member has better supporting effect.

[0024] According to the radial distance, the length of the glass fiber cloth 4 is calculated and cut (as shown in Figure 2 The A / B component epoxy resin is mixed in a ratio of 1:2 and stirred uniformly, and the stirred epoxy resin 6 is applied to the surface of the glass fiber cloth 4 (as shown in Figure 3 The application amount is 250-400g / m2.

[0025] The A / B component ratio of the epoxy resin 6 needs to have a certain curing time, which can not be cured during the inflation process of the air bag 3, so that the glass fiber cloth 4 can slip between the layers with the inflated air bag 3. But when the glass fiber cloth is closely attached to the surface of the surrounding rock, the epoxy resin 6 can quickly cure after stopping the inflation of the air bag. The curing time is about half an hour.

[0026] The glass fiber cloth 4 can better absorb the applied epoxy resin 6, and after the epoxy resin 6 is cured, it can form a circular or elliptical resin-based glass fiber filling member 9 with high strength and good stiffness, which can withstand greater surrounding rock pressure and has better resistance to surrounding rock 2 deformation.

[0027] S4, as shown in Figure 4As shown, multiple layers of fiberglass cloth 4 coated with epoxy resin 6 are wrapped around the outer surface of the airbag 3 and temporarily secured with rubber cable ties 5, which are elastically expandable and contractible. During wrapping, the short sides of the rectangular fiberglass cloth 4 are laid out along the length of the airbag 3, and the long sides of the rectangular fiberglass cloth 4 are wrapped around the side of the airbag 3. The ends of the fiberglass cloth 4 are adhered to the previous layer of fiberglass cloth 4. A PE film with low moisture permeability can be wrapped around the airbag 3 as a release liner before the fiberglass cloth 4 is wrapped around it, making it easier for the airbag 3 to detach from the fiberglass cloth 4.

[0028] S5, such as Figure 5 As shown, the airbag 3 from step S4 is placed in the gap between the steel arch frame 1 and the surrounding rock 2 in the corresponding over-excavation area, with the length direction of the airbag 3 aligned with the longitudinal direction of the chamber and perpendicular to the vertical plane formed by the steel arch frame 1. The airbag 3 is then connected to the air compressor 8 via a hose 7.

[0029] S6, turn on the air compressor 8 to inflate the airbag 3, causing it to expand slowly. The slowly expanding airbag 3 causes the multiple layers of fiberglass cloth 4 wrapped around its surface to stretch and expand slowly, resulting in interlayer slippage. The beginning and end ends of the fiberglass cloth 4 are displaced by a certain distance due to this interlayer slippage (e.g., ...). Figure 6 (As shown).

[0030] As the airbag 3 inflates, the multi-layered fiberglass cloth 4 slowly expands and stretches, causing interlayer slippage. The beginning and end of the fiberglass cloth 4 are displaced by a certain distance due to this interlayer slippage. Although the interlayer slippage of the fiberglass cloth 4 slightly reduces the number of winding layers, the length of the long strip of fiberglass cloth is at least six times the measured radial distance. This length ensures that the beginning and end of the fiberglass cloth 4 still overlap after the interlayer slippage, forming a closed ring-shaped filling component 9.

[0031] Once the fiberglass cloth 4 is tightly attached to the surrounding rock 2, stop inflating the airbag 3 and maintain the internal air pressure of the airbag 3 for a period of time.

[0032] S7, maintain the internal air pressure of the airbag 3 for a period of time (e.g., 15 minutes), and after the epoxy resin 6 has cured, it will form the filling component 9 together with the fiberglass cloth 4 (e.g., Figure 7 (As shown).

[0033] S8, release the gas inside the airbag 3 to shrink it. The shrunken airbag 3 detaches from the filling component 9. Remove the airbag 3 for reuse. Leave the filling component 9 in the gap between the steel arch frame 1 and the surrounding rock 2 in the over-excavated area to form local support for the over-excavated area.

[0034] S9, repeat steps two through eight above the steel arch frame 1 in other over-excavated areas until the support of the over-excavated exposed area of ​​the chamber is completed (e.g., Figure 7The application is illustrated in the accompanying drawings).

[0035] The above merely illustrates the embodiments of the present application, and is not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process conversion, or direct or indirect application in other related technical fields, which is made according to the content of the present application specification and drawings, is also included in the patent protection scope of the present application.

Claims

1. A method for supporting construction of a chamber overbreak, characterized in that, The application relates to a method for constructing a support structure in a chamber. Step one, steel arches (1) are erected along the chamber wall, and a plurality of steel arches (1) are installed along the chamber longitudinal direction at intervals; Step two, the setting position of the filling component is determined according to the chamber geological conditions and the over-excavation region above the steel arch (1); the radial distance of the gap between the surrounding rock (2) and the steel arch (1) at the filling component setting position is measured; Step three, the air bag (3) and the glass fiber cloth (4) are selected according to the radial distance measured in step two; the surface of the glass fiber cloth (4) is coated with the stirred epoxy resin (6); Step four, the surface of the air bag (3) is wrapped with the glass fiber cloth (4) coated with the epoxy resin (6); Step five, the air bag (3) in step four is placed in the gap between the surrounding rock (2) and the steel arch (1) in the over-excavation region at the corresponding position; Step six, the air bag (3) is inflated to expand the air bag (3), and the multiple layers of glass fiber cloth (4) wrapped on the surface of the air bag (3) are caused to slide between layers; when the glass fiber cloth (4) is tightly attached to the surrounding rock (2), the air bag (3) is stopped from being inflated, and the air pressure in the air bag (3) is maintained; Step seven, the air pressure in the air bag (3) is maintained for a period of time, so that the epoxy resin is solidified to form a closed annular resin-based glass fiber filling component (9) together with the glass fiber cloth (4); Step eight, the air in the air bag (3) is discharged to separate the air bag (3) from the filling component (9), the air bag (3) is taken out, and the filling component (9) is left in the gap between the steel arch (1) and the surrounding rock (2) in the over-excavation region to form a local support in the over-excavation region.

2. The method according to claim 1, wherein When the air bag (3) is selected, the diameter of the air bag (3) before expansion is smaller than the radial distance of the gap between the surrounding rock (2) and the steel arch (1) in the over-excavation region, so that the air bag (3) can be placed in the gap after the glass fiber cloth (4) is wrapped.

3. The method according to claim 1, wherein The expanded air bag (3) causes the glass fiber cloth (4) wrapped on the surface of the air bag (3) to be tightly attached to the irregular surface of the surrounding rock (2) in the over-excavation region.

4. The method according to claim 1, wherein In step six, the air pressure in the air bag (3) is maintained for 10-20 min.

5. The method according to claim 1, wherein In step three, the length of the glass fiber cloth (4) is at least six times the measured radial distance, the width of the glass fiber cloth (4) is greater than the width of the steel arch (1) and smaller than the length of the air bag (3).

6. The method according to claim 1, wherein The epoxy resin (6) is an A / B component resin, which can slide between layers together with the glass fiber cloth (4) before solidification; the solidification time of the epoxy resin (6) is 20-40 min.

7. The method according to claim 1, wherein The glass fiber cloth (4) can absorb the epoxy resin (6), and after the epoxy resin (6) is solidified, the glass fiber cloth (4) forms a filling component (9) capable of bearing the pressure of the surrounding rock (2) and resisting the deformation of the surrounding rock (2).

8. The method according to claim 1, wherein, In step four, the glass fiber cloth (4) wrapped on the surface of the air bag (3) is temporarily fixed by using a rubber band (5).

9. The method according to claim 1, wherein, In step five, the air bag (3) is connected with an air compressor (8) through a hose (7); in step six, the air compressor (8) is started to inflate the air bag (3).

10. The method according to any one of claims 1-9, wherein, Step nine, the above steps two to eight are repeated in other over-excavation regions above the steel arch (1) until the support in the over-excavation region of the chamber is completed.

Images