A method for excavating a non-saturated loess tunnel

Abstract

The application discloses a kind of non-saturated loess tunnel excavation methods, comprising the following steps: step S1: whether loess surrounding rock needs to carry out water injection construction;Step S2: if no water injection construction is needed, then jump to step S6, if water injection construction is needed, then carry out next step;Step S3: by pre-lining device is carried out in advance excavation to working face, and water injection passage is excavated in working face;Step S4: precast steel lining is installed in the water injection passage of working face in advance excavation;Step S5: water is passed to precast steel lining;Step S6: excavation is carried out using excavation machinery;Step S7: the process of step S1-S6 is recycled until tunnel excavation is completed.The application guarantees cavern stability, greatly reduces extrusion deformation and convergence phenomenon, water is injected to non-saturated loess working face before excavation, which makes it saturated and softens, facilitates mechanical excavation, can save construction period, improves efficiency;Workers work under the protection of lining set, with high efficiency, good safety, can reduce manpower loss.

Description

Technical Field

[0001] This invention relates to the field of loess tunnel construction technology, specifically to a method for excavating unsaturated loess tunnels. Background Technology

[0002] To meet the demands of transportation infrastructure construction, the number of loess tunnels is increasing. Unsaturated loess tunnels are the most common type. Loess in an unsaturated state has a strength higher than that of general soil but lower than that of rock. Therefore, drilling and blasting methods for unsaturated loess often result in excessive blasting vibrations and collapses. Mechanical excavation, on the other hand, is extremely slow due to the high strength of the soil and causes significant wear and tear on the excavating machinery, greatly slowing down the construction progress and extending the construction period. Both the machinery and labor costs are too high. Currently, there is no good excavation method for saturated loess tunnels. Summary of the Invention

[0003] The purpose of this invention is to provide a method for excavating unsaturated loess tunnels that is highly efficient, safe, reduces manpower and equipment wear and tear, and lowers construction costs.

[0004] This invention is achieved through the following technical solution: a method for excavating unsaturated loess tunnels, comprising the following steps: Step S1: Before construction, determine whether the loess surrounding rock at the working face needs water injection. Step S2: If water injection is not required, proceed to step S6; if water injection is required, proceed to the next step. Step S3: The working face is pre-excavated using a pre-lining device to create a water injection channel. Step S4: Construct a precast steel lining capable of water injection and install it into the water injection channel excavated ahead of the working face; Step S5: Water is introduced into the precast steel lining so that water is injected into the working face. At the same time, the strength of the working face is monitored. Water injection is stopped when the softening degree of the loess surrounding rock at the working face meets the excavation conditions. Step S6: Excavation is carried out using excavation machinery; Step S7: Repeat steps S1 to S6 until the tunnel excavation is completed.

[0005] To better implement the method of the present invention, further, in step S6, after the excavation of the tunnel face with the precast steel lining is completed, a temporary inverted arch is constructed at the bottom of the precast steel lining. The temporary inverted arch and the precast steel lining form a closed lining ring, completing the initial support lining of the tunnel.

[0006] To better implement the method of the present invention, further, in step S1, based on the tunnel advanced geological forecast combined with the strength and moisture content of the loess surrounding rock at the front excavation face, a judgment is made as to whether water injection construction is required for the loess surrounding rock at the tunnel face. If the moisture content of the loess surrounding rock is high or the strength is low, water injection construction is not required; if the moisture content of the loess surrounding rock is low or the strength is high, water injection construction is required.

[0007] To better implement the method of the present invention, the prefabricated steel lining in step S4 is further composed of several hollow arc-shaped steel plates spliced ​​together. One end of the arc-shaped steel plate is provided with a water inlet pipe communicating with the inner cavity of the arc-shaped steel plate, and the other end is provided with a water outlet pipe communicating with the inner cavity of the arc-shaped steel plate. Several immersion holes communicating with the inner cavity of the arc-shaped steel plate are also arranged at the lower part of the arc-shaped steel plate.

[0008] To better implement the method of the present invention, the pre-lining device in step S3 further includes a trolley, the front of which is provided with a tunnel-shaped frame track, a telescopic cutting arm and a lining support mechanism that can move along the frame track are installed at the front of the frame track, the telescopic cutting arm is equipped with a cutter head, the lining support mechanism is provided with a lining installation mechanism that can install prefabricated steel lining, a telescopic frame is provided in the middle of the trolley, a fixed frame is provided on the upper part of the telescopic frame, and a steel lining storage mechanism is fixedly installed on the side of the fixed frame facing the frame track. The steel lining storage mechanism is located above the lining installation mechanism to provide prefabricated steel lining.

[0009] To better implement the method of the present invention, the cutter head further includes a cutter holder, the edge of which is provided with a driveable chain, and the chain is provided with cutter teeth.

[0010] To better implement the method of the present invention, the lining installation mechanism further includes a transport platform, a transmission track is installed on the upper part of the transport platform, limit plates are provided on both sides of the transport platform, and a jacking mechanism is also provided at one end of the transport platform located below the steel lining storage mechanism.

[0011] To better implement the method of the present invention, the steel lining storage mechanism further includes a steel lining storage bin, the upper part of which is provided with a connecting mechanism that is detachably connected to the lining installation mechanism, the lower part of which is open, and an arrangement track is provided at the lower opening. When the steel lining storage bin is fixedly connected to the lining installation mechanism through the connecting mechanism, the arrangement track is located above the lining installation mechanism.

[0012] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The construction method provided by the present invention, due to the pre-set advanced steel lining initial support, better ensures the stability of the tunnel and greatly reduces extrusion deformation and convergence phenomenon; (2) According to the condition of the loess surrounding rock where the tunnel face is located, the present invention injects water into the unsaturated loess tunnel face before excavation to make it saturated and softened, which facilitates mechanical excavation, saves construction time and improves efficiency. (3) The present invention greatly reduces the surface settlement of shallow-buried deep tunnels by utilizing the bearing capacity and structural rigidity of the prefabricated steel initial support. (4) The excavation method provided by the present invention allows on-site workers to operate under the protection of the pre-set initial support lining, which ensures high safety. (5) The present invention has high efficiency and good safety in excavation and lining by using construction machinery, and can greatly reduce manpower consumption. Attached Figure Description

[0013] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a three-dimensional structural diagram of the prefabricated steel lining in this invention; Figure 3 This is a front view of the prefabricated steel lining in this invention; Figure 4 This is a front view of the pre-lining device in this invention; Figure 5 This is a left view of the pre-lining device in this invention; Figure 6 This is a schematic diagram of the planar structure of the cutterhead device of the pre-lining device in this invention; Figure 7 This is a top view of the lining installation mechanism of the pre-lining device in this invention. Figure 8 This is a cross-sectional schematic diagram of the steel lining storage mechanism of the pre-lining device in this invention.

[0014] in: 1—Frame rail, 2—Telescopic cutting arm, 3—Cutter head, 31—Cutter holder, 32—Cutter teeth, 33—Chain, 4—Liner support mechanism, 5—Liner installation mechanism, 51—Transportation platform, 52—Transportation rail, 53—Pushing mechanism, 54—Limiting plate, 6—Steel lining storage mechanism, 61—Steel lining storage bin, 62—Layout rail, 63—Connecting mechanism, 7—Trolley, 8—Fixed frame, 9—Telescopic frame, 10—Precast steel lining, 101—Arc-shaped steel plate, 102—Water inlet pipe, 103—Water outlet pipe, 104—Immersion hole. Detailed Implementation

[0015] To make the objectives, process conditions, and advantages of the present invention clearer, the present invention will be further described in detail with reference to the following embodiments. However, the embodiments of the present invention are not limited thereto. Various substitutions and modifications can be made based on common technical knowledge and conventional means in the art without departing from the above-described technical concept of the present invention, and all such substitutions and modifications should be included within the scope of the present invention. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0016] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0017] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0018] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Example 1:

[0019] This embodiment provides a method for excavating tunnels in unsaturated loess, with the specific process as follows: Figure 1 As shown, it includes the following steps: Step S1: Before construction, determine whether the loess surrounding rock at the working face needs water injection. Step S2: If water injection is not required, proceed to step S6; if water injection is required, proceed to the next step. Step S3: The working face is pre-excavated using a pre-lining device to create a water injection channel. Step S4: Construct a precast steel lining 10 capable of water injection and install it into the water injection channel excavated ahead of the working face; Step S5: Water is circulated into the precast steel lining 10 so that water is injected into the working face. At the same time, the strength of the working face is monitored. Water injection is stopped when the softening degree of the loess surrounding rock at the working face meets the excavation conditions. Step S6: Excavation is carried out using excavation machinery; Step S7: Repeat steps S1 to S6 until the tunnel excavation is completed. Example 2:

[0020] This embodiment, based on the above embodiment, further specifies that in step S6, after the excavation of the tunnel face with the precast steel lining is completed, a temporary invert arch is constructed at the bottom of the precast steel lining. The temporary invert arch and the precast steel lining form a closed lining ring, completing the initial support lining of the tunnel. Because the water content and strength of the loess surrounding rock at the tunnel face increase after water injection, the construction of a temporary invert arch at the bottom of the precast steel lining to form a closed lining ring with it completes the initial support lining of the tunnel. This ensures the support strength of the tunnel, allowing on-site workers to operate under the protection of the lining, thus improving safety. The other parts of this embodiment are the same as those in the above embodiment and will not be repeated. Example 3:

[0021] This embodiment, based on the above embodiment, further specifies that in step S1, a determination is made as to whether water injection is required for the loess surrounding rock at the tunnel face, based on the tunnel's advanced geological forecast combined with the strength and moisture content of the loess surrounding rock at the front excavation face. If the loess surrounding rock has high moisture content or low strength, water injection is not required; if the loess surrounding rock has low moisture content or high strength, water injection is required. The other parts of this embodiment are the same as those in the above embodiment and will not be repeated. Example 4:

[0022] This embodiment, based on the above embodiments, further defines the structure of the precast steel lining 10, such as... Figure 2 , Figure 3As shown, the precast steel lining 10 in step S4 is composed of several hollow arc-shaped steel plates 101 spliced ​​together. One end of the arc-shaped steel plate 101 is provided with a water inlet pipe 102 communicating with the inner cavity of the arc-shaped steel plate 101, and the other end is provided with a water outlet pipe 103 communicating with the inner cavity of the arc-shaped steel plate 101. Several immersion holes 104 communicating with the inner cavity of the arc-shaped steel plate 101 are also arranged at the lower part of the arc-shaped steel plate 101. For unsaturated loess requiring water injection, after the precast steel lining 10 is constructed, a water pump is connected to the inlet pipe 102 of the precast steel lining 10. Using an arc-shaped steel plate 101 as the conduit, water is transmitted through the outlet pipe 103 to adjacent arc-shaped steel plates 101. Several immersion holes 104, connected to the inner cavity of the arc-shaped steel plates 101, are also arranged at the bottom of the arc-shaped steel plates 101 to inject water into the working face, softening the unsaturated loess. Simultaneously, the strength of the working face is monitored. Water injection is stopped when the loess softening meets the excavation conditions, and excavation of the working face commences. Other parts of this embodiment are the same as those in the above embodiment and will not be repeated. Example 5:

[0023] This embodiment further defines the structure of the pre-lining device based on the above embodiments, such as... Figure 4 , Figure 5 As shown, the pre-lining device in step S3 includes a trolley 7. A tunnel-shaped frame track 1 is provided at the front of the trolley 7. A telescopic cutting arm 2 and a lining support mechanism 4 that can move along the frame track 1 are installed at the front of the frame track 1. A cutter head 3 is mounted on the telescopic cutting arm 2. A lining installation mechanism 5 that can install precast steel lining 10 is provided inside the lining support mechanism 4. A telescopic frame 9 is provided in the middle of the trolley 7. A fixed frame 8 is provided on the upper part of the telescopic frame 9. A steel lining storage mechanism 6 is fixedly installed on the side of the fixed frame 8 facing the frame track 1. The steel lining storage mechanism 6 is located above the lining installation mechanism 5 and is used to provide precast steel lining 10. The telescopic cutting arm 2 can move on the frame track 1 to advance the excavation of water injection channels on the tunnel face contour. The lining support mechanism 4, in conjunction with the lining installation mechanism 5, installs the precast steel lining 10 into the excavated water injection channels. The telescopic frame 9 provides the power for the steel lining storage mechanism 6 to move up and down through the fixed frame 8, so that the steel lining storage mechanism 6 provides the precast steel lining 10 to the lining installation mechanism 5. The other parts of this embodiment are the same as those in the above embodiment and will not be described again. Example 6:

[0024] This embodiment further defines the structure of the cutter head 3 based on the above embodiments, such as... Figure 6As shown, the cutterhead 3 includes a cutter holder 31, and a driveable chain 33 is provided on the edge of the cutter holder 31. Cutting teeth 32 are provided on the chain 33. The cutterhead 3 has a structure similar to a chainsaw, specifically designed for the advanced excavation of water injection channels. Its cutting teeth 32 are relatively separated, and driven by the chain 33, it can perform advanced excavation of water injection channels in high-strength, high-moisture loess surrounding rock at the working face under the support of the cutter holder 31. Other parts of this embodiment are the same as those in the above embodiments and will not be described again. Example 7:

[0025] This embodiment further defines the structure of the lining installation mechanism 5 based on the above embodiments, such as... Figure 7 As shown, the lining installation mechanism 5 includes a transport platform 51, with a transmission rail 52 mounted on its upper part. Limiting plates 54 are provided on both sides of the transport platform 51, and a jacking mechanism 53 is also provided at the lower end of the transport platform 51 located in the steel lining storage mechanism 6. The transport platform 51 carries the precast steel lining 10, and the transmission rail 52 transports the precast steel lining 10 to the pre-excavated water injection channel. The limiting plates 54 ensure that the precast steel lining 10 entering the transport platform 51 maintains a consistent direction. The jacking mechanism 53 pushes the precast steel lining 10 stored in the steel lining storage mechanism 6 onto the transport platform 51. Other parts of this embodiment are the same as those in the above embodiment and will not be described again. Example 8:

[0026] This embodiment, based on the above embodiments, further defines the structure of the steel-lined storage mechanism 6, such as... Figure 8 As shown, the steel lining storage mechanism 6 includes a steel lining storage bin 61. The upper part of the steel lining storage bin 61 is provided with a connecting mechanism 63 that is detachably connected to the lining installation mechanism 5. The lower part of the steel lining storage bin 61 is open, and a layout track 62 is provided at the lower opening. When the steel lining storage bin 61 is fixedly connected to the lining installation mechanism 5 via the connecting mechanism 63, the layout track 62 is located above the lining installation mechanism 5. The steel lining storage bin 61 is used to store prefabricated steel linings 10 arranged in the same direction. One prefabricated steel lining 10 is transferred at a time through the layout track 62 via the lower opening. The prefabricated steel lining 10 output from the layout track 62 is pushed into the transport platform 51 by the jacking mechanism 53. Before each delivery of precast steel lining 10 to the lining installation mechanism 5, it needs to be fixedly connected to the lining installation mechanism 5 via the connecting mechanism 63, so that the steel lining storage mechanism 6 moves along the frame track 1 with the lining installation mechanism 5. At this time, the telescopic frame 9 coordinates the height of the steel lining storage mechanism 6, and the trolley 7 coordinates the horizontal position of the steel lining storage mechanism 6. The other parts of this embodiment are the same as those in the above embodiment, and will not be described again.

[0027] It is understood that the working principle and process of the pre-lining device structure according to an embodiment of the present invention, such as the telescopic cutting arm 2 and the jacking mechanism 53, are existing technologies and are well known to those skilled in the art, and will not be described in detail here.

[0028] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for excavating tunnels in unsaturated loess, characterized in that, Includes the following steps: Step S1: Before construction, determine whether the loess surrounding rock at the working face needs water injection. Step S2: If water injection is not required, proceed to step S6; if water injection is required, proceed to the next step. Step S3: The working face is pre-excavated using a pre-lining device to create a water injection channel. Step S4: Construct a precast steel lining (10) capable of water injection and install it into the water injection channel excavated ahead of the working face; the precast steel lining (10) in step S4 is composed of several hollow arc-shaped steel plates (101) spliced ​​together. One end of the arc-shaped steel plate (101) is provided with a water inlet pipe (102) communicating with the inner cavity of the arc-shaped steel plate (101), and the other end is provided with a water outlet pipe (103) communicating with the inner cavity of the arc-shaped steel plate (101). Several immersion holes (104) communicating with the inner cavity of the arc-shaped steel plate (101) are also arranged at the lower part of the arc-shaped steel plate (101). Step S5: Water is circulated into the precast steel lining (10) so that the precast steel lining (10) injects water into the working face. At the same time, the strength of the working face is monitored. Water injection is stopped when the softening degree of the loess surrounding rock where the working face is located meets the excavation conditions. Step S6: Excavation is carried out using excavation machinery; Step S7: Repeat steps S1 to S6 until the tunnel excavation is completed.

2. The method for excavating unsaturated loess tunnels according to claim 1, characterized in that, In step S6, after the excavation of the tunnel face with the precast steel lining is completed, a temporary invert arch is constructed at the bottom of the precast steel lining. The temporary invert arch and the precast steel lining form a closed lining ring, completing the initial support lining of the tunnel.

3. A method for excavating unsaturated loess tunnels according to claim 1 or 2, characterized in that, In step S1, based on the tunnel's advanced geological forecast and the strength and moisture content of the loess surrounding rock at the front excavation face, a judgment is made as to whether water injection construction is required for the loess surrounding rock at the tunnel face. If the loess surrounding rock has high moisture content or low strength, water injection construction is not required. If the loess surrounding rock has low moisture content or high strength, water injection construction is required.

4. A method for excavating unsaturated loess tunnels according to claim 1 or 2, characterized in that, The pre-lining device in step S3 includes a trolley (7), a tunnel-shaped frame track (1) is provided at the front of the trolley (7), a telescopic cutting arm (2) and a lining support mechanism (4) are installed at the front of the frame track (1) and can move along the frame track (1), a cutter head (3) is mounted on the telescopic cutting arm (2), a lining installation mechanism (5) is provided in the lining support mechanism (4) and can install prefabricated steel lining (10), a telescopic frame (9) is provided in the middle of the trolley (7), a fixed frame (8) is provided on the upper part of the telescopic frame (9), a steel lining storage mechanism (6) is fixedly installed on the side of the fixed frame (8) facing the frame track (1), the steel lining storage mechanism (6) is located on the upper part of the lining installation mechanism (5) and is used to provide prefabricated steel lining (10).

5. The method for excavating unsaturated loess tunnels according to claim 4, characterized in that, The cutter head (3) includes a cutter holder (31), and the edge of the cutter holder (31) is provided with a driveable chain (33), and the chain (33) is provided with cutter teeth (32).

6. The method for excavating unsaturated loess tunnels according to claim 4, characterized in that, The lining installation mechanism (5) includes a transport platform (51), a transmission track (52) is installed on the upper part of the transport platform (51), limit plates (54) are provided on both sides of the transport platform (51), and a jacking mechanism (53) is also provided at one end of the transport platform (51) located below the steel lining storage mechanism (6).

7. The method for excavating unsaturated loess tunnels according to claim 4, characterized in that, The steel lining storage mechanism (6) includes a steel lining storage bin (61). The upper part of the steel lining storage bin (61) is provided with a connecting mechanism (63) that can be detachably connected to the lining installation mechanism (5). The lower part of the steel lining storage bin (61) is open, and a layout track (62) is provided at the lower opening. When the steel lining storage bin (61) is fixedly connected to the lining installation mechanism (5) through the connecting mechanism (63), the layout track (62) is located above the lining installation mechanism (5).

Images