A loess tunnel construction method and two working surface structures in single-foot construction

Abstract

A loess tunnel construction method and two working surface structures in single-footage construction, first, determine the excavation surface contour line, drive a steel pipe with grouting holes along the excavation surface contour line, and then grouting; excavate water injection holes on the heading face; after water injection, quickly excavate along the full section of the inner circle; after excavation, spray a concrete layer, set a waterproof layer, and apply secondary lining, at this time, the current footage construction is completed; repeat the above steps to carry out the next footage construction; the present invention injects water into the area to be excavated through the water injection hole, which can reduce the loess strength and construct a water stop layer composed of a steel pipe-grouting body. During the construction process, on the one hand, it can prevent the water injected through the water injection hole from entering the surrounding rock, reduce the surrounding rock strength, and achieve the purpose of softening only the area to be excavated; on the other hand, it plays a protective role, which is conducive to rapid excavation of the full section; the present invention has the characteristics of high efficiency, safety and strong controllability.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel construction, and in particular relates to a loess tunnel construction method and two working surface structures in single-footage construction. Background Art

[0002] With the implementation of my country's western development strategy, transportation infrastructure has developed rapidly. Loess strata are widely distributed in the western region. As the transportation network continues to improve, more and more tunnels need to be built in loess strata. At present, loess tunnel construction is mostly carried out with reference to soft rock tunnel construction methods, often using step method, reserved core soil circular excavation method, CD method and CRD method. Although these methods can ensure the normal construction of loess tunnels, these methods do not take into account the particularity of loess, resulting in low construction efficiency; loess has obvious water-immersion and collapsible properties. If this characteristic can be fully considered during construction, the construction efficiency can be greatly improved. Summary of the invention

[0003] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a loess tunnel construction method and two working surface structures in single-foot construction, which can fully utilize the characteristic of loess being soaked and collapsed, and control its soaking and collapsing range through isolation structures and support structures to improve construction efficiency, and has the characteristics of high efficiency, safety and strong controllability.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A loess tunnel construction method comprises the following steps:

[0006] Step 1: Determine the contour line of the excavation surface; determine the length of a footage to be 5m to 15m, and carry out the construction of the current footage;

[0007] Step 2: Along the contour line of the excavation surface, a circle of steel pipes 1 with grouting holes 7 are driven into the loess surrounding rock at an external insertion angle of 1° to 5°, and the steel pipes 1 are closely attached to each other to form a steel pipe ring layer 6;

[0008] Step 3: Grouting is performed through the steel pipe 1 into the surrounding rock by means of grouting equipment, and a water stop layer 9 is formed by the steel pipe ring layer 6 and the grouting body 8;

[0009] Step 4: excavate 3 to 5 water injection holes 2 on the tunnel face; at this time, the first stage of construction is completed, and the second stage of construction is carried out; in the second stage of construction, water is first injected into the water injection holes 2 to soften the loess;

[0010] Step 5: Use a cantilever tunneling machine to excavate the contour surface along the inner wall of the water stop layer 9;

[0011] Step 6: After the excavation section is formed, a concrete layer 3 is sprayed on the inner circle of the steel pipe ring layer 6, and a waterproof layer 4 is set on the inner circle of the concrete layer through a waterproof board;

[0012] Step 7: After the waterproof layer 4 is set, a secondary lining 5 is applied to the inner wall of the waterproof layer 4, and tunnel ancillary facilities are applied;

[0013] Step 8: When one construction footage is completed, repeat steps 2 to 7 to carry out the next construction footage until the tunnel is broken through.

[0014] The length of the water injection hole 2 is 1.5 to 2.5 meters shorter than the length of the steel pipe 1; the portion of the steel pipe 1 that is longer than the water injection hole serves as the overlap length between the current footage and the next footage.

[0015] The thickness of the concrete layer 3 is 3-7 cm.

[0016] The steel pipe 1 has a length of 8 to 12 meters, a diameter of 3 to 5 cm, and a wall thickness of 0.5 to 0.8 cm.

[0017] A row of grouting holes 7 are respectively arranged on two opposite sides of the steel pipe 1 , the diameter of the grouting holes 7 is 1 to 3 cm, and the intervals between the grouting holes 7 are 5 to 10 cm.

[0018] A working surface structure for completing a single-stage construction in loess tunnel construction comprises a water-stop layer 9, wherein a plurality of water injection holes 2 are arranged in the soil inside the water-stop layer 9.

[0019] The water stop layer 9 includes a steel pipe ring layer 6 and a grouting body 8; the steel pipe ring layer 6 is formed by steel pipes 1 tightly attached to each other.

[0020] The steel pipe 1 is driven into the loess surrounding rock at an external insertion angle of 1° to 5°.

[0021] The steel pipe 1 has a length of 8 to 12 meters, a diameter of 3 to 5 cm, and a wall thickness of 0.5 to 0.8 cm.

[0022] A row of grouting holes 7 is respectively provided on two opposite sides of the steel pipe 1 .

[0023] The diameter of the grouting holes 7 is 1 to 3 cm, and the intervals between the grouting holes 7 are 5 to 10 cm.

[0024] A working surface structure at the end of a two-stage construction with a single footage in loess tunnel construction comprises a water stop layer 9, an inner circle of the water stop layer 9 is provided with a concrete layer 3, a waterproof layer 4 is applied on the inner side of the concrete layer 3, and a secondary lining 5 is applied on the inner side of the waterproof layer 4.

[0025] The water stop layer 9 includes a steel pipe ring layer 6 and a grouting body 8; the steel pipe ring layer 6 is formed by the steel pipes 1 tightly attached to each other.

[0026] The steel pipe 1 is driven into the loess surrounding rock at an external insertion angle of 1° to 5°.

[0027] The steel pipe 1 has a length of 8 to 12 meters, a diameter of 3 to 5 cm, and a wall thickness of 0.5 to 0.8 cm.

[0028] A row of grouting holes 7 is respectively provided on two opposite sides of the steel pipe 1 .

[0029] The diameter of the grouting holes 7 is 1 to 3 cm, and the intervals between the grouting holes 7 are 5 to 10 cm.

[0030] The thickness of the concrete layer 3 is 3-7 cm.

[0031] The beneficial effects of the present invention are as follows: injecting water into the area to be excavated through the water injection hole 2 can reduce the strength of loess; during the construction process, a steel pipe ring layer 6 and a grouting body 8 are used to form a water-stop layer 9, which can prevent the water in the water injection hole 2 from entering the surrounding rock and reduce the strength of the surrounding rock, thereby achieving the purpose of softening only the area to be excavated. In addition, the water-stop layer 9 can also be used as the main supporting structure; the application of the concrete layer 3 does not need to play a supporting role, but only needs to play a leveling role, which can improve construction efficiency and save investment; the protective role played by the water-stop layer 9 is conducive to rapid excavation of the entire section; the use of rapid excavation of the entire section can reduce construction disturbances; the application of the secondary lining 5 can form a support ring in time to ensure safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the working surface structure at the end of a single-footage one-stage construction in the loess tunnel construction of the present invention.

[0033] Figure 2 It is the working surface structure at the end of the two-stage construction of a single advance in the loess tunnel construction of the present invention.

[0034] Figure 3 It is a side sectional structural diagram of the working surface after the completion of the second stage of single-footage construction.

[0035] Figure 4 It is a schematic structural diagram of the steel pipe 1.

[0036] In the figure: 1. Steel pipe; 2. Water injection hole; 3. Concrete layer; 4. Waterproof layer; 5. Secondary lining; 6. Steel pipe ring layer; 7. Grouting hole; 8. Grouting body; 9. Waterstop layer. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0038] See also Figure 1 and Figure 2 , a loess tunnel construction method, comprising the following steps:

[0039] Step 1: Determine the contour line of the excavation surface; determine the length of a footage to be 8m, and carry out the construction of the current footage;

[0040] Step 2: Along the contour line of the excavation surface, a circle of steel pipes 1 with grouting holes 7 are driven into the loess surrounding rock at an external insertion angle of 2°, and the steel pipes 1 are closely attached to each other to form a steel pipe circle layer 6;

[0041] Step 3: Grouting is performed through the steel pipe 1 into the surrounding rock by means of grouting equipment, and a water stop layer 9 is formed by the steel pipe ring layer 6 and the grouting body 8;

[0042] Step 4: excavate three water injection holes 2 on the tunnel face; at this time, the first stage of construction is completed, and the second stage of construction is carried out; in the second stage of construction, water is first injected into the water injection holes 2 to soften the loess;

[0043] Step 5: Use a cantilever tunneling machine to excavate the contour surface along the inner wall of the water stop layer 9;

[0044] Step 6: After the excavation section is formed, a concrete layer 3 is sprayed on the inner circle of the steel pipe ring layer 6, and a waterproof layer 4 is set on the inner circle of the concrete layer through a waterproof board;

[0045] Step 7: After the waterproof layer 4 is set, the secondary lining 5 is applied as a whole, and the tunnel ancillary facilities are applied;

[0046] Step 8: When one construction footage is completed, repeat steps 2 to 7 to carry out the next construction footage until the tunnel is broken through.

[0047] See also Figure 1 and Figure 2 The length of the water injection hole 2 is 8m. In actual use, the length of the water injection hole 2 is 2m shorter than the length of the steel pipe 1. This 2m is used as the overlap length of the next footage.

[0048] See also Figure 2 , the thickness of the concrete layer 3 is 5 cm.

[0049] See also Figure 4 The steel pipe 1 has a length of 10 m, a diameter of 3 cm and a wall thickness of 0.6 cm.

[0050] A row of grouting holes 7 are respectively arranged on two opposite sides of the steel pipe 1 , the diameter of the grouting holes 7 is 2 cm, and the intervals between the grouting holes 7 are 7.5 cm.

[0051] A cantilever tunneling machine is used to quickly excavate the entire profile surface along the inner wall of the steel pipe 1 .

[0052] See also Figure 1A working surface structure at the end of a single-stage construction in loess tunnel construction comprises a water-stop layer 9, wherein a plurality of water injection holes 2 are arranged in the soil inside the water-stop layer 9.

[0053] The water stop layer 9 includes a steel pipe ring layer 6 and a grouting body 8 .

[0054] See also Figure 1 and Figure 2 The length of the water injection hole 2 is 8m. In actual use, the length of the water injection hole 2 is 2m shorter than the length of the steel pipe 1. This 2m is used as the overlap length of the next footage.

[0055] See also Figure 3 The steel pipe ring layer 6 is formed by steel pipes 1 tightly attached to each other; the steel pipe 1 is driven into the loess surrounding rock at an external insertion angle of 2°.

[0056] See also Figure 4 The steel pipe 1 has a length of 10 m, a diameter of 3 cm and a wall thickness of 0.6 cm.

[0057] See also Figure 4 A row of grouting holes 7 are respectively provided on two opposite sides of the steel pipe 1; the diameter of the grouting holes 7 is 2 cm, and the interval between the grouting holes 7 is 7.5 cm.

[0058] A working surface structure at the end of a two-stage construction with a single footage in loess tunnel construction comprises a water stop layer 9, an inner circle of the water stop layer 9 is provided with a concrete layer 3, a waterproof layer 4 is applied on the inner side of the concrete layer 3, and a secondary lining 5 is applied on the inner side of the waterproof layer 4.

[0059] See also Figure 1 and Figure 2 The water stop layer 9 includes a steel pipe ring layer 6 and a grouting body 8; the steel pipe ring layer 6 is formed by the steel pipes 1 tightly attached to each other.

[0060] See also Figure 1 and Figure 2 The length of the water injection hole 2 is 8m. In actual use, the length of the water injection hole 2 is 2m shorter than the length of the steel pipe 1. This 2m is used as the overlap length of the next footage.

[0061] See also Figure 2 , the thickness of the concrete layer 3 is 5 cm.

[0062] See also Figure 3 The steel pipe 1 is driven into the loess surrounding rock at an external insertion angle of 2°.

[0063] See also Figure 4 The steel pipe 1 has a length of 10 m, a diameter of 3 cm and a wall thickness of 0.6 cm.

[0064] See also Figure 4A row of grouting holes 7 are respectively provided on two opposite sides of the steel pipe 1; the diameter of the grouting holes 7 is 2 cm, and the interval between the grouting holes 7 is 7.5 cm.

[0065] The working principle of the present invention is: inject water into the area to be excavated through the water injection hole 2 to soften the soil in the area to be excavated and reduce the soil strength; set up a steel pipe-grouting body water-stop layer to prevent the water in the water injection hole 2 from entering the surrounding rock and reducing the strength of the surrounding rock; use full-section rapid excavation to reduce construction disturbance; and apply secondary lining 5 to form a support ring to ensure safety.

Claims

1. A loess tunnel construction method, characterized in that: The following steps are involved: Step 1: Determine the contour line of the excavation surface; determine the length of a footage to be 5m~15m, and carry out the construction of the current footage; Step 2: Along the contour line of the excavation surface, a circle of steel pipes (1) with grouting holes (7) are driven into the loess surrounding rock at an external insertion angle of 1° to 5°, and the steel pipes (1) are closely attached to each other to form a steel pipe circle layer (6); Step 3: Grouting is performed through the steel pipe (1) into the surrounding rock using grouting equipment, and a water stop layer (9) is formed by the steel pipe ring layer (6) and the grouting body (8); Step 4: 3 to 5 water injection holes (2) are excavated on the tunnel face; the length of the water injection hole (2) is 1.5 to 2.5 meters shorter than the length of the steel pipe (1); the length of the steel pipe (1) that is longer than the water injection hole (2) is used as the overlap length between the current footage and the next footage; at this point, the first stage of construction is completed, and the second stage of construction is carried out; in the second stage of construction, water is firstly injected into the water injection hole (2) to soften the loess; Step 5: using a cantilever tunneling machine to excavate the contour surface along the inner wall of the water stop layer (9); Step 6: After the excavation section is formed, a concrete layer (3) is sprayed on the inner circle of the steel pipe ring layer (6), and a waterproof layer (4) is provided on the inner circle of the concrete layer through a waterproof board; Step 7: After the waterproof layer (4) is set, the secondary lining (5) is applied as a whole, and the tunnel ancillary facilities are constructed; Step 8: When one construction footage is completed, repeat steps 2 to 7 to carry out the next construction footage until the tunnel is broken through.

2. A loess tunnel construction method according to claim 1, characterized in that: The steel pipe (1) has a length of 8 to 12 meters, a diameter of 3 to 5 cm, and a wall thickness of 0.5 to 0.8 cm.

3. A loess tunnel construction method according to claim 1 or 2, characterized in that: A row of grouting holes (7) are respectively provided on two opposite sides of the steel pipe (1); the diameter of the grouting holes (7) is 1 to 3 cm, and the intervals between the grouting holes (7) are 5 to 10 cm.

4. A loess tunnel construction method according to claim 1, characterized in that: The thickness of the concrete layer (3) is 3-7 cm.

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