A tunnel shield excavation construction method

Abstract

The present invention discloses a tunnel shield excavation construction method, which relates to the technical field of tunnel construction. The method comprises the following steps: step S1: driving a plurality of vacuum flower pipes in the rock and soil to be excavated on the tunnel face, the vacuum flower pipes being connected to a vacuum pump to form a negative pressure vacuum system; step S2: spraying a quick-setting sealing cementitious material on the tunnel face; step S3: vacuuming and consolidating the rock and soil to be excavated; step S4: excavating the edge of the tunnel excavation section to form a trench; step S5: arranging steel supports in the arch trench, setting micropiles at the arch foot position to support the steel supports, spraying fiber concrete, and forming a primary lining support system; step S6: after the support system is completed, the remaining core soil of the tunnel face is excavated, a waterproof coating is sprayed on the surface of the primary lining, and a secondary lining support is applied to prepare for the next cycle. The method fully utilizes the soil arch effect of the surrounding rock and soil, the steel supports, and the sprayed concrete system to form a shield, thereby improving the stability of the tunnel surrounding rock and soil and increasing the efficiency of mechanical construction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel construction, in particular to a tunnel shield tunneling construction method. BACKGROUND

[0002] Tunnels can make vehicles directly cross mountains or rivers, avoiding the waste of time and distance caused by detours. With the increasing improvement of public and railway networks and urban subway construction planning, a large number of underground tunnels are built. In the construction process of underground tunnels, the main construction methods at present include shield method, TBM method, drill and blast method, etc.

[0003] The shield method and the TBM method are both round full-face tunneling, and the adaptability of the working environment is different. The TBM is a hard rock tunneling machine, and the shield is a soft soil tunneling machine. When the properties of surrounding rock change greatly, it will bring great difficulties to construction. The risks and difficulties in the construction of high ground stress and large deformation soft rock are extremely great. At the same time, the tunnel construction is often in the shape of a horseshoe or a rectangle section, and the circular section often causes a large excavation surface and high energy consumption.

[0004] The drill and blast method is suitable for a wide range of strata, but the construction speed is slow, the construction conditions are poor, and the surrounding environment is greatly disturbed. The stability of the surrounding structures and facilities is often affected during construction. The drill and blast method often uses grouting, anchor rods, pipe roof and other technologies for reinforcement. The technical principle is to increase the stability of the surrounding rock soil by changing external factors, without fully utilizing the self characteristics of the rock and soil such as soil arching effect. In addition, there are deficiencies such as poor reinforcement effect, long construction period and poor economy due to the uncontrollable grouting range and quality, and the inability of anchor rods and pipe roofs to fully reinforce the surrounding rock soil. Moreover, the overall carbon emission is high.

[0005] Therefore, how to provide a tunnel shield tunneling method suitable for various soil layers is a problem that needs to be solved in the current tunnel construction.

[0006] The present application provides a tunnel shield tunneling method suitable for any soil layer. This method can overcome the deformation of soft rock, prevent the occurrence of rock burst phenomenon of surrounding rock, save energy, ensure safety and speed, and overcome the limitations of geological conditions with small and flexible construction equipment, fast construction speed and low cost. SUMMARY

[0007] (I) Technical problems solved

[0008] In view of the deficiencies of the prior art, the present application provides a tunnel shield tunneling construction method to solve at least one technical problem proposed in the background art.

[0009] (II) Technical solutions

[0010] To achieve the above-mentioned purposes, the technical scheme adopted by the present application is: a tunnel shield tunneling construction method, the steps of the tunnel shield tunneling construction method comprising:

[0011] Step S1: A plurality of drainage pipes and vacuum flower pipes are arranged in the rock-soil mass to be excavated at the tunnel face, and the vacuum flower pipes are connected with a vacuum pump to form a negative pressure vacuum system;

[0012] Step S2: A rapid-setting sealing cementitious material is sprayed at the tunnel face;

[0013] Step S3: The rock-soil mass to be excavated is subjected to vacuum consolidation reinforcement;

[0014] Step S4: The tunnel edge is excavated to form an arched groove;

[0015] Step S5: A steel support is arranged in the arched groove, and a micro pile is arranged at the arch foot to support the steel support to form a support system;

[0016] Step S6: After the support system is completed, the remaining soil is excavated, and a permanent support is applied to prepare for the next cycle.

[0017] Preferably, the drainage pipes are located at the lower part of the tunnel face.

[0018] Preferably, the vacuum flower pipes include horizontal vacuum pipes and inclined vacuum pipes, wherein the horizontal vacuum pipes are arranged at the middle part of the tunnel face, and the inclined vacuum pipes are arranged at the edge of the tunnel face.

[0019] Preferably, the horizontal vacuum pipes are arranged in a quincunx or square form at the tunnel face, the diameter of the horizontal vacuum pipes is 2-10 cm, the distance between the horizontal vacuum pipes is 0.5-2.0 m, and the depth of the arrangement is 3-5 times the length of a single excavation.

[0020] Preferably, the inclined vacuum pipes are inclined outwardly from the tunnel, and the angle of the inclined arrangement is 5-30°.

[0021] Preferably, the rapid-setting sealing cementitious material sprayed in Step S2 is a mixture of 30%-50% cement, 40%-50% medium-coarse sand, 3%-8% calcium aluminate, 1%-2% sodium carbonate, and 0.2%-1% sodium chlorate, and any one or several of chlorinated emulsion, acrylic emulsion, and polyurethane emulsion are mixed to form a base material. During construction, the base material is mixed with the same weight of emulsion and a suitable amount of water to form a mixture, which is then sprayed and constructed on the tunnel face.

[0022] Preferably, during the vacuum consolidation reinforcement of the rock-soil mass to be excavated in Step S3, the vacuum degree is -20 to -80 kPa, and the vacuum duration can be 2-24 h.

[0023] Preferably, the arched groove formed by excavation in Step S4 has a width of 1-2 m and a depth of a single excavation length.

[0024] Preferably, the steel support in step S5 is an I-beam or H-beam, which has a shape consistent with the inner contour of the tunnel, and the micro piles at the arch foot are inserted into the precast piles to form a ductile core pile after being cast in situ.

[0025] Preferably, the step S6 is a waterproof coating spraying construction on the primary lining surface, wherein the modified coating is formed by any one or a mixture of several of chlorinated emulsion, acrylic emulsion and polyurethane emulsion, and 1% to 10% of KH560 silane coupling agent.

[0026] (Three) beneficial effects

[0027] The present application provides a tunnel shield tunneling construction method, which has the following beneficial effects compared with the prior art:

[0028] The soil arching effect of the surrounding rock is fully utilized, and the soil arching effect and the steel support system form a shield, thereby greatly improving the stability of the tunnel surrounding rock, enabling full-face excavation, and having the advantages of low comprehensive energy consumption, safety and reliability.

[0029] The pore pressure in the water-rich soft layer can be reduced by the drainage pipe and vacuum flower pipe. According to the effective stress principle and shear strength theory, the effective stress of the soil will increase, and the important index of the surrounding rock soil, the effective shear strength, will also increase. The mechanical properties of the surrounding rock soil are fully utilized. In addition, since the transmission range of vacuum in the soil is large, the above reinforcement effect is applied to the entire surrounding rock soil, and the traditional grouting, pipe shed and anchor rod can only reinforce part of the soil, so the reinforcement effect of the present application is better.

[0030] Compared with the grouting method, the present application does not use a large amount of grouting, and the use of cement-based cementitious materials with high carbon emission is less. Compared with the pipe shed and anchor rod reinforcement, the present application reduces the use of steel materials, and the drainage pipe and vacuum pipe can be reused, which has significant low-carbon environmental protection. BRIEF DESCRIPTION OF DRAWINGS

[0031] The present application will be further described below in conjunction with the drawings and examples:

[0032] Figure 1 It is a front view of the horizontal and inclined vacuum pipes and drainage pipes;

[0033] Figure 2 It is a front view of the excavated arch-shaped groove;

[0034] Figure 3 It is a front view of the steel support and micro pile;

[0035] Figure 4 It is a front view of the full-face excavation;

[0036] Figure 5Side view of horizontal, inclined vacuum tube and drain pipe arrangement;

[0037] Figure 6 Side view of steel support and micro pile;

[0038] Figure 7 Side view of full-face excavation;

[0039] Figure 8 Whole schematic diagram of tunnel shield tunneling construction;

[0040] Among them, 1 is an inclined vacuum tube; 2 is a horizontal vacuum tube; 3 is a drain pipe; 4 is an arched groove body; 5 is a steel support; 6 is a micro flexible core pile; and 7 is a tunnel permanent support. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application is described clearly and completely. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0042] In order to better understand the above technical scheme, the above technical scheme will be described in detail below in combination with the drawings in the specification and specific embodiments:

[0043] As shown in the drawings of the specification, Figures 1-8 The embodiments of the present application provide a tunnel shield tunneling construction method,

[0044] Step S1: In the tunnel face of soft soil, soft rock and other strata, a plurality of drain pipes 3 and vacuum flower tubes are punched into the rock-soil body to be excavated, and the vacuum flower tubes are connected with a vacuum pump to form a negative pressure vacuum system. Specifically, a larger diameter drainage hole is punched at the lower part of the face, and the drain pipe 3 is placed in the drainage hole, which can effectively reduce the pore pressure in the water-rich stratum and improve the effective stress of the soil body, thereby improving the strength of the soil body; the vacuum flower tube is divided into an inclined vacuum tube 1 and a horizontal vacuum tube 2, wherein the horizontal vacuum tube 2 is arranged in the middle of the face, and the inclined vacuum tube 1 is arranged at the edge of the face, which can reinforce a part of the rock-soil body outside the tunnel contour; the side wall of the vacuum tube is provided with holes for applying vacuum to the surrounding rock-soil body. The horizontal vacuum tube 2 can be arranged in the form of a plum blossom, a square, etc. at the face, the diameter of the vacuum tube can be 2-10 cm, the tube spacing is 0.5-2.0 m, and the punching depth each time is 3-5 times the single excavation length. The inclined vacuum tube 1 is inclined to the outside of the tunnel, and the angle of the inclined punching is 5-30°, and other parameters can be the same as those of the horizontal vacuum tube 2. The inclined vacuum tube 1 and the horizontal vacuum tube 2 can adopt two forms of front closed and rear punched hole and all punched holes.

[0045] Step S2: Spray the quick-setting sealing cementitious material on the working face to make the soil to be excavated in a closed state. The cementitious material base is mixed with 30-50% cement, 40-50% medium-coarse sand, 3-8% calcium aluminate, 1-2% sodium carbonate and 0.2-1% sodium chlorate for 5-10 minutes to form the base, and any one or several of chlorinated emulsion, acrylic emulsion and polyurethane emulsion is mixed with the base and the same weight of emulsion to spray on the working face. The functions of quick setting, water stopping and air impermeability are realized in the wet or water state. After the cementitious material hardens, the soil to be excavated is kept in an air impermeable state.

[0046] Further, the quick-setting sealing cementitious material is sprayed on the working face to make the soil to be excavated in a closed state, and a pre-vacuum test is conducted after sealing to detect the sealing property. If the sealing property is not good, the sealing material is sprayed repeatedly.

[0047] Step S3: The soil to be excavated is vacuum consolidated to increase the effective stress and strength of the soil to be excavated to the limit value of excavation. The vacuum degree during the vacuum process can be -20 to -80 kPa, and the vacuum duration can be 2-24 hours, which needs to be determined according to the engineering characteristics of the soil. Specifically, after the effective stress and strength of the soil to be excavated are increased to the limit value of excavation, the next step is performed.

[0048] Step S4: Excavate the tunnel edge to form an annular arch groove 4. The groove is excavated, and the width of the arch groove is 1-2 m, and the depth is the single excavation distance, which can be 0.5-4 m. Specifically, in the implementation process, the tunnel annular edge can be excavated by using a shield shell excavation construction device to form the arch groove 4.

[0049] Step S5: Steel support 5 is arranged in the arch groove 4 to support the surrounding rock, and micro-tough core pile 6 is set at the arch foot position of soft rock or soft soil to support the steel support 5, and 10-20 cm thick fiber concrete is sprayed to form an initial lining support system with the steel support. The micro-tough core pile 6 has a pile diameter of 300-400 mm and a pile length of 3-4 m, and C20-C40 plain concrete is poured and then pressed into a prefabricated pipe pile (pipe pile diameter 250-350 mm).

[0050] Step S6: After the shield shell support is completed, the remaining soil can be excavated, and a modified moisture-resistant waterproof coating formed by mixing any one or several of chlorinated emulsion, acrylic emulsion and polyurethane emulsion and then dropping 1-10% KH560 silane coupling agent is sprayed on the surface of the support shell as a waterproof layer of the permanent support 7 of the tunnel. Prepare for the next cycle. Specifically, one cycle is to repeat steps S1-S5 until the tunnel excavation is completed.

[0051] A tunneling method that utilizes or creates the arch effect of the surrounding rock, excavates and supports in an orderly manner to achieve shield stabilization, and is used for continuous excavation and rapid construction. It fully utilizes the arch effect of the surrounding rock mass itself or creates the arch effect, and at the same time forms a shield stabilization structure with the superimposed support system, thereby greatly improving the stability of the tunnel surrounding rock and soil. It can quickly excavate the entire section and is a tunneling technology with low comprehensive energy consumption, high safety and reliability, and is suitable for various geological conditions.

[0052] The tunnel shield excavation construction method provided in the above embodiment fully utilizes the soil arch effect of the surrounding rock and soil itself, and uses the soil arch effect and the support structure to form a superimposed shield, which has the advantages of greatly improving the stability of the tunnel surrounding rock and soil, allowing full-section excavation, low comprehensive energy consumption, safety and reliability.

[0053] Furthermore, in soft rock or soft soil surrounding rock, the pore pressure in the water-rich weak layer can be reduced through the drainage pipe 3 and the vacuum flower pipe. According to the effective stress principle and shear strength theory, the effective stress of the soil will increase, and the effective shear strength, an important indicator for controlling the surrounding rock soil, will also increase accordingly, making full use of the mechanical properties of the surrounding rock soil itself. In addition, since the vacuum transmission range within the soil is relatively large, the above-mentioned reinforcement effect acts on the entire surrounding rock soil, while traditional grouting, pipe shed, anchor rod and other technologies can only reinforce part of the soil. Therefore, the reinforcement effect of this technology is better.

[0054] After the surrounding rock mass of soft rock or soft soil is strengthened, a soil arch effect can be formed above and in front of the tunnel face. The soil arch above can reduce the pressure acting on the tunnel and significantly reduce tunnel settlement; while the soil arch in front can reduce the pressure acting on the tunnel face and significantly reduce the horizontal earth pressure. As a result, the external force on the surrounding rock and soil is smaller, which is more conducive to its stability and the deformation of the tunnel is controllable and small.

[0055] The excavated arch trench reduces the amount of excavation required without support, speeding up construction. It also provides space for the steel supports 5 and the micro-tough core piles 6. Placing the micro-tough core piles 6 at the arch foot of the steel supports 5 effectively reduces uneven settlement and stability of the support system.

[0056] The soil arching effect and the support system (formed by the steel supports 5 and the micro-tough core piles 6) form a shield, which jointly increases the stability of the surrounding rock and soil, thereby reducing construction costs.

[0057] The tunnel face is sprayed with sealing cementitious waterproof material to keep the soil to be excavated on the front side of the tunnel face in a sealed state, thereby ensuring the vacuum effect.

[0058] Due to the existence of soil arch effect, the horizontal soil pressure on the tunnel face is relatively small, so full-section excavation can be adopted, which improves construction efficiency.

[0059] Compared with the grouting method, the embodiment of the application does not have large amount of grouting, and cement-based cementitious materials with high carbon emission are less used; compared with the pipe shed and anchor rod reinforcement, the embodiment of the application reduces the use of steel materials, and the drain pipe and the vacuum pipe can be reused, and has remarkable low-carbon environmental protection.

[0060] It should be noted that in this paper, the term "including", "containing" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or equipment.

[0061] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A tunnel shield excavation construction method, characterized in that: The tunnel shield excavation construction method comprises the following steps: Step S1: a plurality of drainage pipes (3) and vacuum pipes are installed on the tunnel face in the rock and soil to be excavated, and the vacuum pipes are connected to a vacuum pump to form a negative pressure vacuum system; The vacuum flower pipe comprises a horizontal vacuum pipe (2) and an oblique vacuum pipe (1), wherein the horizontal vacuum pipe (2) is arranged in the middle of the tunnel face, and the oblique vacuum pipe (1) is arranged at the edge of the tunnel face; the horizontal vacuum pipe (2) is arranged in a plum blossom or square form on the tunnel face, the diameter of the horizontal vacuum pipe (2) is 2 to 10 cm, the pipe spacing of the horizontal vacuum pipe (2) is 0.5 to 2.0 m, and the driving depth is 3 to 5 times the single excavation length; The inclined vacuum tube (1) is inclined in a manner of spreading outward from the tunnel, and the angle of the inclined installation is 5 to 30 degrees; Step S2: spraying a quick-setting sealing cementitious material on the tunnel face to seal the rock and soil to be excavated; Step S3: vacuum consolidation and reinforcement are performed on the rock and soil to be excavated, so that the effective stress and strength of the rock and soil to be excavated are increased to the excavation limit; Step S4: excavating the edge of the tunnel excavation section to form an arched trench (4); Step S5: Arrange the steel support (5) in the arch groove (4), and drive micro-tough core piles (6) at the arch foot position to support the steel support (5), and spray 10-20 cm thick fiber concrete to form a primary lining support system with the steel support; Step S6: After the primary lining support system is completed, the remaining core soil of the tunnel face is excavated, and a waterproof coating is sprayed on the surface of the primary lining support system to apply permanent support (7) and prepare for the next cycle; In the step S3, during the vacuum consolidation and reinforcement process of the excavated rock and soil, the vacuum degree of the vacuum is -20 to -80 kPa, and the vacuum time is 2 to 24 hours.

2. The tunnel shield excavation construction method according to claim 1, characterized in that: The drainage pipe (3) is located at the lower part of the tunnel face.

3. The tunnel shield excavation construction method according to claim 1, characterized in that: The quick-setting sealing cementitious material sprayed in step S2 is a base material formed by mixing and stirring components in weight of 30% to 50% cement, 40% to 50% medium-coarse sand, 3% to 8% calcium aluminate, 1% to 2% sodium carbonate and 0.2% to 1% sodium chlorate. During construction, any one or more of chloroform emulsion, acrylic emulsion and polyurethane emulsion are mixed, and the base material is mixed with the same weight of emulsion with water and stirred, and then sprayed on the face of the tunnel for construction.

4. The tunnel shield excavation construction method according to claim 1, characterized in that: The arched trench (4) formed by excavation in step S4 has a width of 1 to 2 m and a depth equal to the length of a single excavation.

5. The tunnel shield excavation construction method according to claim 1, characterized in that: In step S5, the steel support (5) is an I-steel or H-steel, and its shape is consistent with the inner contour of the tunnel. The micro tough core pile (6) at the arch foot position is a prefabricated pile or a cast-in-place pile.

6. The tunnel shield excavation construction method according to claim 1, characterized in that: In step S6, a waterproof coating is sprayed on the surface of the primary lining support system, wherein the waterproof coating is a modified coating formed by mixing any one or more of chloroprene emulsion, acrylic emulsion, and polyurethane emulsion and adding 1% to 10% of KH560 silane coupling agent.

Images