AU2021103534A4

AU2021103534A4 - A buffer layer structure of surrounding rock deformation control in underground engineering and supporting structure

Info

Publication number: AU2021103534A4
Application number: AU2021103534A
Authority: AU
Inventors: Weizhong Chen; Xianjun Tan; Hongming Tian; Guojun WU; Chaoxuan Zhang
Original assignee: Wuhan Institute of Rock and Soil Mechanics of CAS
Current assignee: Wuhan Institute of Rock and Soil Mechanics of CAS
Priority date: 2021-02-05
Filing date: 2021-06-22
Publication date: 2021-09-09
Anticipated expiration: 2029-06-22
Also published as: CN214303850U

Abstract

The present invention discloses a buffer layer structure of surrounding rock deformation control in underground engineering and supporting structure. The buffer layer structure comprises a buffer absorber arranged along the cross section of a tunnel or roadway, wherein the buffer absorber comprises a tube body, in which the tube body is filled with foam concrete material, both ends of the tube body are blocked by a plug, and the axis of the tube body is arranged along the longitudinal direction of the tunnel or roadway. The present invention perfectly combines the outer thin shell is not damaged under the condition of large deformation and the inorganic porous media of the built-in foamed concrete can be large deformation. It overcomes the shortcoming of cracking and breaking in the process of large deformation of foamed concrete and low strength of thin-walled structure. The combination of the two can maintain the overall integrity of the structure under the condition of constant resistance pressure, perfect to achieve the purpose of buffer layer. DRAWINGS 1 Fig.1 3 4 5 6 Fig.2 1/2 9 10 Fig.3 2/2

Description

DRAWINGS

1

Fig.1

3 4 5 6

Fig.2

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10

Fig.3

2/2

A BUFFER LAYER STRUCTURE OF SURROUNDING ROCK DEFORMATION CONTROL IN UNDERGROUND ENGINEERING AND SUPPORTING STRUCTURE

Field of the Invention

The present invention discloses a buffer layer structure of surrounding rock

deformation control in soft rock large deformation underground engineering and

supporting structure including the buffer layer structure.

Background of the Invention

Information of the Related Art part is merely disclosed to increase the

understanding of the overall background of the present invention, but is not

necessarily regarded as acknowledging or suggesting, in any form, that the

information constitutes the prior art known to a person of ordinary skill in the art.

Large deformation disasters in soft rock underground engineering generally have

the characteristics of large deformation magnitude and long deformation development

time, which will cause serious damage to the project in the construction stage and

long-term service stage. For the prevention and control of surrounding rock

deformation in underground engineering, from the initial strong rigid support to the

present compression support, many supporting technologies have been produced in

this process, among which the buffer layer support has become an important

development direction for the prevention and control of large deformation disasters of

soft rock. At present, scholars have proposed many types of buffer layer materials,

including: telescopic steel frame, pressure anchor, compressible concrete, foam

concrete, ceramsite compressible layer, gravel, rubber, aluminum foam, wood cube,

polyurethane, etc., and developed corresponding buffer support structures based on

the stress and deformation characteristics of each material.

The inventor found that the existing buffer layer materials and buffer support structures have the following major problems:

(1) Many buffer layer materials are expensive, such as rubber, aluminum foam;

(2) The compressibility of buffer layer material or buffer support structure is not

enough, such as: compressible concrete, compressible ceramsite layer, telescopic steel

frame, wooden square, gravel;

(3) Buffer layer material fire resistance, durability and environmental protection

is not guaranteed, such as: wooden square, polyurethane;

(4) Foamed concrete material has the characteristics of high compressibility, low

cost and good durability. The batch use in large section underground engineering is

restricted by two conditions. First, the casting height can not be too high, otherwise it

will defoaming, affecting the construction progress; Second, foamed concrete is prone

to brittle fracture and spalling under the action of load, which not only reduces the

buffer and energy absorption effect, but also easily leads to safety threats such as

falling blocks.

Summary of the Invention

To resolve the technical problem in the prior art, the present invention provides a

buffer layer structure of surrounding rock deformation control in soft rock large

deformation underground engineering and a supporting structure.

In order to realize the above purpose, the present invention is realized through

the following technical scheme:

In the first aspect, the embodiment of the present invention provides a buffer

layer structure suitable for surrounding rock deformation control of soft rock large

deformation underground engineering. It comprises a buffer absorber arranged along

the cross section of a tunnel or roadway, wherein the buffer absorber comprises a tube

body, in which the tube body is filled with foam concrete material, both ends of the

tube body are blocked by a plug, and the axis of the tube body is arranged along the

longitudinal direction of the tunnel or roadway.

In combination with the first aspect, the embodiment of the present invention provides a first possible embodiment of the first aspect, wherein the pipe body is made of thin iron sheet, or is a PVC or a PE.

In combination with the first aspect, the embodiment of the present invention provides a second possible embodiment of the first aspect, wherein the thickness of the tube body is 0.2-2mm and the outer diameter is 50150mm.

In combination with the first aspect, the embodiment of the present invention provides a second possible embodiment of the first aspect. The radial and longitudinal compressive strength of the buffer energy absorber is between 0.5 and 3MPa, and the deformation rate is less than 70% without damage.

In combination with the first aspect, the embodiment of the present invention provides a third possible embodiment of the first aspect, wherein the density range of the foamed concrete material is 250-500 kg/m3 .

In combination with the first aspect, the embodiment of the present invention provides a fourth possible embodiment of the first aspect. Along the radial direction of the tunnel or roadway, two layers of buffer absorber are arranged.

In the second aspect, the embodiment of the present invention also provides a supporting structure with reinforced concrete lining, which is composed of surrounding rock, initial supporting layer, buffer absorber layer and reinforced concrete lining layer from the outer layer to the inner layer along the cross section of the tunnel or roadway.

In the third aspect, the embodiment of the present invention also provides a support structure without reinforced concrete lining, which is composed of surrounding rock, energy absorbing buffer layer and initial support layer from the outer layer to the inner layer along the cross section of the tunnel or roadway.

The beneficial effects of an embodiment of the present invention are as follows:

1. The present invention perfectly combines the outer thin shell is not damaged under the condition of large deformation and the inorganic porous media of the built-in foamed concrete can be large deformation. It overcomes the shortcomings of cracking and breaking of foamed concrete and low strength of thin-walled structure in the process of large deformation. The combination of the two can maintain the overall integrity of the structure under the condition of constant resistance pressure, perfect to achieve the purpose of buffer layer.

2. The buffer energy absorber of the present invention can be prefabricated, with light weight, convenient functional site installation, small construction labor intensity, high efficiency, no pollution and dust generation.

3. The buffer energy absorber is laid between the conventional support structure and the constrained object. Taking the tunnel and roadway as an example, the buffer energy absorber is generally laid longitudinal along the tunnel between the initial support and the secondary lining or between the initial support and the surrounding rock.

Brief Description of the Drawings

The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary examples of the present invention and descriptions thereof are used to explain the present invention, and do not constitute an improper limitation of the present invention.

Fig. 1 is a structural schematic diagram of the buffer energy absorber disclosed by the present invention;

Fig. 2 is the schematic diagram of the supporting structure with reinforced concrete lining disclosed by the present invention;

Fig. 3 is the schematic diagram of the support structure of the unreinforced concrete lining disclosed by the present invention;

In the figures: the space or size between each other is exaggerated to show the positions of each part. The schematic diagram is only used for schematic purposes.

1 pipe body; 2 foamed concrete; 3 concrete layer; 4 steel mesh; 5 steel arch; 6

buffer absorber; 7 waterproof structure; 8 reinforced concrete lining; 9 surrounding

rock; 10 energy absorber layer; 11 initial support.

Detailed Description of Embodiments

It should be pointed out that the following detailed descriptions are all exemplary

and aim to further illustrate the present invention. Unless otherwise specified, all

technological and scientific terms used in the present invention have the same

meanings generally understood by those of ordinary skill in the art of the present

invention.

It should be noted that the terms used herein are merely for describing specific

embodiments, but are not intended to limit exemplary embodiments according to the

present invention. As used herein, unless otherwise clearly stated in the present

invention, the singular form is also intended to include the plural form. In addition, it

should also be understood that when the terms "include" and/or "comprise" are used

in the Description, they indicate features, steps, operations, devices, components,

and/or combinations thereof.

For the convenience of description, if the words "upper", "lower", "left" and

"right" appear in the present invention, it only means that it is consistent with the

upper, lower, left, and right directions of the drawing itself, and does not limit the

structure. It is only for the convenience of describing and simplifying the description

of the present invention, rather than indicating or implying that the device or element

referred to must have a specific orientation, be constructed and operated in a specific

orientation, and therefore cannot be understood as a limitation of the present

invention.

As introduced in the background art, the prior art has shortcomings. In order to

solve the above technical problems, the present invention proposes a buffer layer

structure of surrounding rock deformation control in underground engineering and

supporting structure.

A typical way of embodiment of the present invention, as shown in figure 1, a

buffer layer structure of surrounding rock deformation control in underground

engineering. The buffer layer comprises a plurality of buffer energy absorbers, which

can be arranged one layer, two layers or multiple layers along the cross section of the

tunnel or roadway, and can be set according to the actual needs.

The structure of the buffer absorber is shown in figure 1, which includes an inner

layer and an outer layer. The outer layer is a tube body 1 with both ends open, which

is made of thin iron sheet, or directly made of PVC or PE. The inner part of the tube

body 1 is filled with foam concrete 2. By adjusting the proportion of foam soil and the

material of pipe body, it can adapt to different working conditions such as light weight,

fire prevention, non-toxic, high compressibility, waterproof and corrosion resistance.

Preferably, the diameter of the outer tube body can be made according to the

requirements of the field installation and operation space, and 50mm-150mm can be

selected.

Further, the thickness of the outer wall of the buffer absorber can be made

according to the compression performance required by the working condition, and the

size is generally 0.2mm-5mm, so as to ensure that the shape of the tube can change to

% without damage.

Further, the radial/longitudinal compressive strength of the buffer absorber

should consider the force of the protected object, and the strength is generally

between 0.5Mpa and 3Mpa. The strength can be adjusted by adjusting the density,

diameter and material of the tube body, in which the density is generally 250500

kg/m 3 .

Further, the buffer absorber can be set as a round tube or square tube according

to the field installation operating space, and the length can be adjusted according to

the requirements of the field installation operating space.

Further, the above buffer absorber can be prepared in advance by means of

prefabrication. The preparation method is as follows: The pipe is intercepted as the required length, and the one end is placed upright after blocking the plug. At the same time, foamed concrete with different densities is prepared, filled into the pipe through the feeding pipe, and then blocked with a plug. It is maintained in the standard curing room for 28d, that is, the buffer absorber required for support can be made.

Further, the shape of the tube body can be adjusted to be round, square or layered,

or the structure of the tube body can be adjusted to be solid filling or hollow filling to

adapt to the installation and operation space under different working conditions.

The buffer absorber perfectly combines the characteristics of the large

deformation of the outer thin shell without damage and the large deformation of the

inorganic porous media of the built-in foamed concrete. It overcomes the shortcoming

of cracking and breaking in the process of large deformation of foamed concrete and

low strength of thin-walled structure. The combination of the two can maintain the

overall integrity of the structure under the condition of constant resistance pressure,

perfect to achieve the purpose of buffer layer.

The above mentioned buffer layer structure of surrounding rock deformation

control in underground engineering can be applied to various support structures, such

as the support structure with reinforced concrete lining as shown in figure 2 and the

support structure without reinforced concrete lining as shown in figure 3.

When applied to the supporting structure with reinforced concrete lining, the

specific construction sequence is as follows:

Step 1: Spraying concrete of surrounding rock after underground chamber

excavation;

Step 2: Completing the initial support measures for erecting steel arch frame,

hanging mesh, spray anchor and so on;

Step 3: Hanging a waterproofing board;

Step 4: Locating and installing a single or multi-layer buffer absorbing material;

Step 5: Casting and moulding concrete;

The supporting structure formed by the above construction method is shown in

Figure 2. Along the cross section of the tunnel or roadway, from the outer layer to the

inner layer are shotcrete layer 3, steel mesh 4, steel arch 5, buffer energy absorber 6,

waterproof structure 7, and reinforced concrete lining 8.

When applied to the supporting structure without reinforced concrete lining, the

specific construction sequence is as follows:

Step 1: Spraying concrete of surrounding rock after underground chamber

excavation;

Step 2: If necessary, a waterproofing board can be hung;

Step 3: Locating and installing a single or multi-layer buffer absorbing material;

Step 4: Completing the initial support measures for erecting steel arch frame,

hanging mesh, spray anchor and so on;

It is understood that steel arches can be made of section steel arches or

stretchable U-frames.

The supporting structure formed by the above construction method is shown in

figure 3, along the cross section of tunnel or roadway, and the outer layer to the inner

layer is surrounding rock 9, buffer suction support structure 10, initial support 11.

The above are only the preferred embodiments of the present invention and are

not used to limit the present invention. The present invention may be subject to

various modifications and variations for the technical personnel in the field. Any

modification, equivalent replacement, improvement etc. made within the spirit and

principles of the present invention shall be included in the scope of protection of the

present invention.

Claims

1. A buffer layer structure of surrounding rock deformation control in underground engineering, comprising a buffer absorber arranged along the cross section of a tunnel or roadway; wherein the buffer absorber comprises a tube body filled with foam concrete material at ends blocked by a plug, and the axis of the tube body is arranged along the longitudinal direction of the tunnel or roadway.

2. The buffer layer structure of surrounding rock deformation control in underground engineering according to claim 1, wherein the pipe body is made of thin iron sheet, PVC or PE.

3. The buffer layer structure of surrounding rock deformation control in underground engineering according to claim 1, wherein the thickness of the tube body is 0.2-2mm and the outer diameter is 50-150mm.

4. The buffer layer structure of surrounding rock deformation control in underground engineering according to claim 1, wherein a radial compressive strength and a longitudinal compressive strength of the buffer energy absorber are between 0.5 and 3MPa, and when a deformation rate of the shock absorber is within 70%, the outer wall of the shock absorber is not damaged.

5. The buffer layer structure of surrounding rock deformation control in underground engineering according to claim 1, wherein a density range of the foamed concrete material is 250-500 kg/m3 .

6. The buffer layer structure of surrounding rock deformation control in underground engineering according to claim 1, wherein two layers of buffer absorber are set along the radial direction of the tunnel or roadway.

7. A supporting structure with reinforced concrete lining, the supporting structure comprising the buffer layer structure of surrounding rock deformation control in underground engineering according to any one of claim 1-6.

8. The supporting structure with reinforced concrete lining according to claim 7, comprising surrounding rock, initial supporting layer, buffer absorber layer and reinforced concrete lining layer from outer layer to inner layer along the cross section of tunnel or roadway.

9. A supporting structure with unreinforced concrete lining, the supporting structure

comprising the buffer layer structure of surrounding rock deformation control in

underground engineering according to any one of claim 1-6.

10. The supporting structure with unreinforced concrete lining according to claim 9,

wherein, along the cross section of tunnel or roadway, from outer layer to inner layer

of the supporting structure is the surrounding rock, the energy absorption buffer layer

and the initial support layer successively.