Construction structure of water-rich loess stratum tunnel underground excavation method

Abstract

The utility model discloses a construction structure of a water-rich loess stratum tunnel underground excavation method, which relates to the technical field of tunnel engineering and comprises a pipe shed structure, a primary support, a secondary lining, an advanced small guide pipe, a full-length bonding type mortar anchor rod, a grouting pipe and a temporary drainage pipe. The pipe shed structure is located at a tunnel opening, a steel pipe in the pipe shed structure extends into a soil body, a primary support and a secondary lining are sequentially arranged on the inner side of the tunnel, and advanced small guide pipes are arranged on a tunnel face and surrounding rock of the tunnel. A plurality of full-length bonding type mortar anchor rods, grouting pipes and temporary drainage pipes are arranged on the arch portion of the tunnel. The tunnel excavation device is suitable for water-rich loess stratum tunnel excavation, and the accurate condition of complex surrounding rock within the pipe shed range is known in advance through pipe shed construction; the stability of soft and broken rock stratums is effectively improved through advanced small guide pipe grouting; the stability and the long-term use effect of the tunnel are guaranteed through secondary lining; the construction progress and cost control are effectively guaranteed, and the safety coefficient of construction is greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of tunnel engineering, in particular to a construction structure for the mined - tunneling method in a water - rich loess stratum. Background Technique

[0002] As an indispensable structure in the urban drainage system, the drainage tunnel may pass through various soil layers during its construction process. As is well known, the loess structure is relatively complex and highly water - sensitive. During the construction of mined - tunneling in water - rich loess areas, the distribution of the loess aquifer in multiple strata varies greatly. Coupled with rainfall, irrigation infiltration recharge, and the existence of groundwater, the soil layer around the tunnel is prone to softening, resulting in a reduction in strength, which will seriously threaten the safety of tunnel construction and operation.

[0003] Therefore, providing a construction structure for the mined - tunneling method in a water - rich loess stratum, by adopting the methods of pipe - shed reinforcement and advanced small - duct grouting support, to improve the support effect and structural strength, ensure the safety of tunnel construction process and operation, and ensure that the tunnel maintains a long - term stable state, has important engineering significance. Content of the Utility Model

[0004] The purpose of the utility model is to provide a construction structure for the mined - tunneling method in a water - rich loess stratum, and solve the problems of poor support effect and low structural strength existing in the existing construction structure.

[0005] To solve the above - mentioned technical problems, the utility model adopts the following technical solutions:

[0006] A construction structure for the mined - tunneling method in a water - rich loess stratum of the utility model includes a pipe - shed structure, primary support, secondary lining, advanced small - ducts, fully - grouted mortar bolts, grouting pipes, and temporary drain pipes.

[0007] The pipe - shed structure is located at the tunnel entrance, the steel pipes in the pipe - shed structure extend into the soil mass, the primary support and the secondary lining are sequentially arranged on the inner side of the tunnel, and the advanced small - ducts are arranged on the tunnel face and surrounding rock; a plurality of fully - grouted mortar bolts, grouting pipes, and temporary drain pipes are arranged on the arch of the tunnel, and the fully - grouted mortar bolts, grouting pipes, and temporary drain pipes are distributed radially.

[0008] Preferably, the pipe - shed structure includes a support body and steel pipes; the steel pipes are arranged outside the tunnel excavation contour, one end of the steel pipes penetrates into the stable stratum, and the other end is arranged on the support body.

[0009] Preferably, the steel pipe is a multi - joint connection structure, and the length of a single section of the steel pipe is 2m or 3m; the steel pipe is made of hot - rolled seamless steel pipe; the number of the steel pipes is eighteen, the circumferential spacing of the steel pipes is 40cm, and the two - section steel pipes are butt - jointed by threaded steel pipes, and the joints on adjacent steel pipes are staggered by 1m.

[0010] Preferably, the initial support includes a concrete layer, I - beams and locking foot bolts; the I - beams are arranged at equal intervals in the excavation direction of the tunnel, adjacent I - beams are connected by tie rods and covered with a steel mesh, the concrete layer is sprayed on the steel mesh, the concrete layer is divided into upper and lower parts, and the lower sides of the upper part of the concrete layer are connected to the tunnel sidewall through the locking foot bolts.

[0011] Preferably, a plurality of the advanced small pipes are arranged on the heading face at a ring spacing of 0.4m, a longitudinal spacing of 1.5m, and an outward - pitching angle of 24° to 26°, and the output ends of the advanced small pipes are located in the surrounding soil.

[0012] Preferably, the grouting pipes are arranged in a plum - blossom pattern at a ring spacing of 2m and a longitudinal spacing of 2m on the top of the tunnel, and the output ends of the grouting pipes are located outside the initial support.

[0013] Preferably, a waterproof layer is provided between the initial support and the secondary lining.

[0014] Preferably, a protective layer is further provided above the bottom of the secondary lining.

[0015] Compared with the prior art, the beneficial technical effects of the present utility model are as follows:

[0016] The present utility model provides a construction structure that adopts pipe - shed reinforcement and advanced small - pipe grouting support, and is applicable to the excavation of tunnels in water - rich loess strata in grade - V and grade - IV surrounding rock sections where the surrounding rock is extremely broken; through pipe - shed construction, the accurate situation of the complex surrounding rock within the pipe - shed range can be understood in advance; through advanced small - pipe grouting, the stability of soft and broken rock strata can be effectively improved; through the secondary lining, the stability and long - term use effect of the tunnel can be ensured; it can not only effectively ensure the construction progress and cost control, but also greatly improve the construction safety factor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The following further explains the present utility model with reference to the attached drawings.

[0018] Figure 1 It is a schematic diagram of the construction structure of the present utility model for the cut - and - cover method of tunnels in water - rich loess strata;

[0019] Figure 2 It is a longitudinal sectional view of the construction structure of the present utility model for the cut - and - cover method of tunnels in water - rich loess strata.

[0020] Description of reference numerals in the drawings: 1. Pipe shed structure; 2. Initial support; 3. Secondary lining; 4. Advance small duct; 5. Fully grouted mortar bolt; 6. Grouting pipe; 7. Temporary drain pipe; 8. Protective layer; 100. Tunnel

[0021] 101. Steel pipe; 201. Concrete layer; 202. I-beam; 203. Foot-locking bolt Specific implementation mode

[0022] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present utility model clearer and more understandable, the present utility model will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0023] As Figure 1-2 shown, a construction structure for the mined tunneling method in a water-rich loess stratum includes a pipe shed structure 1, an initial support 2, a secondary lining 3, an advance small duct 4, a fully grouted mortar bolt 5, a grouting pipe 6 and a temporary drain pipe 7;

[0024] The pipe shed structure 1 is located at the entrance of the tunnel 100, the steel pipe 101 in the pipe shed structure 1 extends into the soil mass, the initial support 2 and the secondary lining 3 are sequentially arranged inside the tunnel 100, and the advance small duct 4 is arranged on the heading face and surrounding rock of the tunnel 100; a plurality of the fully grouted mortar bolts 5, the grouting pipe 6 and the temporary drain pipe 7 are arranged on the arch part of the tunnel 100, and the fully grouted mortar bolts 5, the grouting pipe 6 and the temporary drain pipe 7 are distributed radially; the ground load on the top of the mined tunnel 100 shall not exceed 20 kPa. The construction party shall reasonably plan the construction site layout and reasonably arrange the waste soil stacking and heavy-load transportation channels to ensure construction safety.

[0025] Specifically, the pipe shed structure 1 includes a support body and a steel pipe 101; the steel pipe 101 is arranged outside the tunnel excavation contour, one end of the steel pipe 101 extends into the stable stratum, and the other end is arranged on the support body; the pipe shed structure 1 forms a structure similar to a simply supported beam by arranging the steel pipe 101 outside the tunnel excavation contour, with one end extending into the stable stratum and the other end supported on the support body, which can effectively transfer and disperse the stress from the surrounding rock and avoid instability caused by local stress concentration.

[0026] Specifically, the steel pipe 101 is a multi-section connection structure, and the length of each single section of the steel pipe 101 is 2m or 3m; the steel pipe 101 is made of hot-rolled seamless steel pipe; the number of the steel pipes 101 is eighteen, the circumferential spacing of the steel pipes 101 is 40cm, and the two sections of the steel pipes 101 are butt-jointed by threaded steel pipes, and the joints on the adjacent steel pipes 101 are staggered by 1m; in order to ensure that the drill pipe joints have sufficient strength, stiffness and toughness, the threaded steel pipes are made of the same material as the drill pipe, and internal screw threads are processed at both ends, and the wall thickness of the threaded steel pipe ≥ 10mm.

[0027] Specifically, the initial support 2 includes a concrete layer 201, an I-beam 202 and a foot-locking bolt 203; the I-beams 202 are arranged at equal intervals in the excavation direction of the tunnel 100, and the adjacent I-beams 202 are connected by connecting rods and covered with a steel mesh, and the concrete layer 201 is sprayed on the steel mesh. The concrete layer 201 is divided into upper and lower parts, and the two sides below the upper part of the concrete layer 201 are connected to the side wall of the tunnel 100 through the foot-locking bolts 203; when excavating the tunnel 100, the bench cut method is used for excavation, and the tunnel section is divided into upper bench, core soil and lower bench and other parts. First, the upper bench is excavated and supported in time, then the core soil is excavated, and finally the lower bench is excavated and the support is completed; the excavation of the tunnel 100 should preferably be carried out by mechanical and manual cooperation, and the cyclic advance of each excavation part is the same as the spacing of one frame of steel structure; the initial support 2 closely follows to achieve "excavate and support simultaneously, and close into a ring as early as possible".

[0028] Specifically, a plurality of the advanced small pipes 4 are arranged on the heading face at a circumferential spacing of 0.4m, a longitudinal spacing of 1.5m, and an external insertion angle of 24° to 26°, and the output ends of the advanced small pipes 4 are located in the surrounding soil; before excavation, small steel pipes are driven obliquely upward or into the surrounding rock near the heading face of the advanced small pipes 4 for grouting to ensure the stability of the heading face; the tunnel 100 is reinforced by injecting single-fluid cement slurry and admixtures are incorporated; in the construction, for the sections with serious water seepage or water gushing, cement-sodium silicate double-fluid grouting is used for waterproofing; the grouting pressure is 0.5 - 1.0 Mpa;

[0029] Specifically, the grouting pipes 6 are arranged in a plum blossom shape at a circumferential spacing of 2m and a longitudinal spacing of 2m on the top of the tunnel 100, and the output ends of the grouting pipes 6 are located outside the initial support 2.

[0030] Specifically, a waterproof layer is provided between the initial support 2 and the secondary lining 3.

[0031] Specifically, a protective layer 8 is further provided above the bottom of the secondary lining 3.

[0032] The construction process of the present utility model is as follows:

[0033] Pipe shed construction: When installing the pipe shed, first install the steel pipe with perforations at odd-numbered holes for advanced support. After grouting is completed, install the steel pipes at even-numbered holes to check the grouting quality. During drilling, the boom of the jumbo must be firmly pressed against the heading face to prevent excessive vibration from affecting the drilling accuracy. The construction accuracy requirements of the pipe shed are extremely high. The hole positions should be marked by measuring and setting out. After the drilling rig is in place, the coordinates of the front and rear ends of the drill pipe should be measured, and each hole should be numbered.

[0034] Excavation of soil and initial support: Excavation and support of the upper bench: After the advanced support of the arch is completed, the upper bench circular pilot drift can be excavated. The length of the reserved core soil should be 3 - 5m, and the width should be 1 / 3 - 1 / 2 of the tunnel excavation width.

[0035] Excavation and support of the lower bench: The excavation of the core soil and the lower bench should be carried out after the support of the upper bench is completed and the sprayed concrete strength reaches 70% of the design strength.

[0036] Excavation and support of the floor: The floor is excavated by machinery and trimmed manually. The excavation must be carried out in one full-section excavation and closed in a ring. The one-time excavation length of the floor shall not be greater than 6m.

[0037] Grouting support with advanced small pipe 4: At the predetermined position, wind the hemp rope with clay into a spindle-shaped plug no less than the drilling diameter, insert the advanced small pipe 4 into the hole, and then use the jumbo to push the pipe into the hole, 5 - 10cm away from the bottom of the hole, so that the hemp rope plug is fully pressed against the hole wall. Then fill the clay in the remaining part between the hemp rope and the hole mouth to ensure tightness and prevent slurry leakage. Before grouting, carefully check and repair the machinery and equipment, and conduct a trial run with clean water. If problems are found, they should be promptly eliminated and repaired to ensure that they are in good working condition. After the grouting is completed, in order to prevent pipeline blockage, the hole connection at the hole mouth should be removed as soon as possible, and the pipeline should be flushed with the clean water pump to avoid the remaining slurry in the pipeline from coagulating and blocking the pipeline. Thoroughly clean all the machinery and equipment, put them away and withdraw them outside the tunnel, and regularly check and maintain them to ensure that they are in a good state of no air leakage and no blockage for use in the next section of grouting.

[0038] Secondary lining: The whole lining jumbo is used for construction. The formwork for pouring the secondary lining 3 adopts a fully hydraulic track self-propelled whole lining jumbo. The concrete is pumped into the formwork. A grouting pipe 6 and an exhaust pipe are reserved at the crown of each ring to ensure the close contact between the concrete at the crown and the surrounding rock. The concrete is vibrated by an attached vibrator, supplemented by an inserted vibrator. In the section of reinforced concrete lining, the steel bars are cut and processed outside the tunnel, bent into shape, and then tied or assembled and welded inside the tunnel. The steel bar tying is constructed using a multi-functional working platform frame, which together with the initial support 2 forms a composite lining to achieve the purposes of strengthening the support, optimizing the route drainage system, beautifying the appearance, and facilitating the installation of equipment.

[0039] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0040] The above-described embodiments are only descriptions of the preferred modes of the present utility model and do not limit the scope of the present utility model. Without departing from the design spirit of the present utility model, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present utility model shall fall within the protection scope determined by the claims of the present utility model.

Claims

1. A construction structure for the tunneling method in water-rich loess strata by means of blind excavation, characterized in that: It includes a pipe shed structure (1), primary support (2), secondary lining (3), advanced small pipes (4), fully grouted mortar bolts (5), grouting pipes (6) and temporary drain pipes (7); The pipe shed structure (1) is located at the entrance of the tunnel (100). The steel pipes (101) in the pipe shed structure (1) extend into the soil mass. The primary support (2) and the secondary lining (3) are successively arranged inside the tunnel (100). The advanced small pipes (4) are arranged on the heading face and surrounding rock of the tunnel (100). A plurality of the fully grouted mortar bolts (5), the grouting pipes (6) and the temporary drain pipes (7) are arranged on the arch of the tunnel (100), and the fully grouted mortar bolts (5), the grouting pipes (6) and the temporary drain pipes (7) are distributed radially.

2. The construction structure of the tunneling method for water-rich loess strata according to claim 1, characterized in that: The pipe shed structure (1) includes a support body and steel pipes (101); the steel pipes (101) are arranged outside the tunnel excavation contour. One end of the steel pipes (101) extends into the stable stratum, and the other end is arranged on the support body.

3. The construction structure of the tunneling method in water-rich loess stratum according to claim 2, characterized in that: The steel pipes (101) are of a multi-section connection structure. The length of each single section of the steel pipes (101) is 2 m or 3 m; the steel pipes (101) are made of hot-rolled seamless steel pipes; the number of the steel pipes (101) is eighteen, the circumferential spacing of the steel pipes (101) is 40 cm, and the joints between two sections of the steel pipes (101) are connected by threaded steel pipes, and the joints on adjacent steel pipes (101) are staggered by 1 m.

4. The construction structure of the tunneling method in water-rich loess stratum according to claim 1, characterized in that: The primary support (2) includes a concrete layer (201), I-beams (202) and foot-locking bolts (203); the I-beams (202) are arranged at equal intervals in the excavation direction of the tunnel (100). Adjacent I-beams (202) are connected by tie rods and covered with a steel mesh. The concrete layer (201) is sprayed on the steel mesh. The concrete layer (201) is divided into upper and lower parts, and the two sides below the upper part of the concrete layer (201) are connected to the side wall of the tunnel (100) through the foot-locking bolts (203).

5. The construction structure of the tunneling method for water-rich loess strata according to claim 1, characterized in that: A plurality of the advanced small pipes (4) are arranged on the heading face at a circumferential spacing of 0.4 m, a longitudinal spacing of 1.5 m, and an external insertion angle of 24° to 26°, and the output ends of the advanced small pipes (4) are located in the surrounding soil mass.

6. The construction structure of the tunneling method in the water-rich loess stratum according to claim 1, wherein: The grouting pipes (6) are arranged in a plum blossom shape on the top of the tunnel (100) at a circumferential spacing of 2 m and a longitudinal spacing of 2 m, and the output ends of the grouting pipes (6) are located outside the primary support (2).

7. The construction structure of the tunneling method for water-rich loess strata according to claim 1, characterized in that: A waterproof layer is arranged between the primary support (2) and the secondary lining (3).

8. The construction structure of the tunneling method for water-rich loess strata according to claim 1, characterized in that: A protective layer (8) is also arranged above the bottom of the secondary lining (3).

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