A method for constructing tunnels by cutting and excavating.

Abstract

This application discloses a method for constructing a mined tunnel, relating to the field of tunnel engineering technology. It solves the problems of shield tunneling, which can only use circular cross-sections and has high construction costs, and drill-and-blast method, which has high safety risks and poor lining quality. The main steps of this mined tunnel construction method are: using multiple circular cutterheads continuously distributed along the tunnel outline to excavate the surrounding strata, forming a ring-shaped advance excavation outline; the multiple circular cutterheads are arranged alternately along the tunnel outline, with adjacent circular cutterheads staggered in the tunnel excavation direction; a support shield is installed within the ring-shaped advance excavation outline; the support shield advances with the circular cutterheads, serving as cyclic advance support for the tunnel; under the protection of the support shield, the central strata are excavated and loaded out of the tunnel; and tunnel support is erected. This mined tunnel construction method is applicable to the construction of tunnels in municipal and railway projects.

Description

Technical Field

[0001] The embodiments of this application relate to, but are not limited to, the field of tunnel engineering, and in particular to a method for constructing a cut-and-cover tunnel. Background Technology

[0002] With the continuous advancement of urbanization in my country, large-span shallow-buried tunnels are becoming increasingly common, including more and more cases of tunnels passing under railways, roads, subway stations and other structures. This has led to increasingly higher requirements for settlement control during tunnel construction. Tunnel construction needs to solve construction challenges such as large spans, cut-and-cover excavation, and small-scale construction settlement. Common related technologies include drill-and-blast tunnel construction and shield tunnel construction.

[0003] The general process of drill-and-blast tunnel construction is as follows: blast holes are drilled at the tunnel face, explosives are loaded, and blasting takes place at the face. Each blast depth varies depending on geological conditions. After ventilation, dust suppression, and smoke removal, initial support construction includes shotcreting, steel frame erection, and anchor bolt installation. Subsequently, waterproofing membranes are laid, and secondary lining and internal structures are poured to complete the tunnel. The lining structure of a drill-and-blast tunnel generally consists of initial support and secondary lining. Initial support includes shotcreting, anchor bolts, and steel frames, while secondary lining is typically cast-in-place concrete. When geological conditions are poor, to suppress ground deformation and improve construction safety, advanced support is required before excavation at the tunnel face, including pre-support pipe roofs (larger diameter steel pipes), pre-support small-diameter steel pipes (smaller diameter steel pipes), and pre-support anchor bolts. This advanced support is generally placed within a certain range above the tunnel, such as within a 140-degree range.

[0004] The main process of shield tunneling is as follows: the cutterhead rotates and cuts the strata, and the excavated soil is discharged through a slurry shield (slurry shield) or an earth pressure shield (earth pressure shield). Precast tunnel segments are assembled inside the shield tail. While the shield is cutting through the strata, the tunnel segments are pushed out to the shield tail. Grouting is simultaneously injected between the excavation profile and the lining. Finally, the internal tunnel structure is poured to complete the tunnel. Shield tunnel lining typically uses only a single layer of precast concrete tunnel segments, and the gap between the lining and the excavation profile is filled by simultaneous grouting.

[0005] Of the above construction methods, the shield tunneling method can only use a circular cross-section and has a high project cost, while the drill and blast method has a high safety risk and poor lining quality. Summary of the Invention

[0006] The tunnel construction method provided in this application is applicable to tunnels with various cross-sections, and has high support reliability and low tunneling safety risk.

[0007] This application provides a method for constructing a cut-and-cover tunnel, which mainly includes the following steps: using multiple circular cutterheads continuously distributed along the tunnel outline to excavate the surrounding strata to form an annular advance excavation outline; the multiple circular cutterheads are arranged alternately along the tunnel outline, and adjacent circular cutterheads are staggered in the tunnel excavation direction; a support shield is provided within the annular advance excavation outline; the support shield advances with the circular cutterheads to serve as the cyclic advance support for the tunnel; under the protection of the support shield, the central strata are excavated and loaded out of the tunnel; and tunnel support is erected.

[0008] The tunnel construction method provided in this application employs multiple circular cutterheads continuously distributed along the tunnel outline, each rotating to excavate the surrounding strata and create multiple circular excavation outlines continuously distributed along the tunnel outline. These circular excavation outlines are connected to form a ring-shaped excavation outline. Since the circular cutterheads excavate the surrounding strata, this ring-shaped excavation outline advances ahead of the central strata. Because the ring-shaped advanced excavation outline is formed by combining multiple continuously distributed circular excavation outlines, the tunnel outline is not limited by the outline of the tunneling machinery, i.e., the circular cutterhead. This construction method can excavate tunnels with circular cross-sections, and can also excavate... For tunnels with non-circular cross-sections, such as elliptical or square tunnels, excavation is carried out according to the tunnel contour based on construction requirements, avoiding over-excavation and wasting energy. Simultaneously, the excavation contour excavated by a single circular cutterhead is relatively small compared to the entire tunnel contour area, resulting in less disturbance to the strata during excavation and simpler support, facilitating the construction of shallow-overburden tunnels. Furthermore, multiple circular cutterheads are arranged alternately along the tunnel contour, with adjacent circular cutterheads staggered along the tunnel excavation direction. This avoids interference between adjacent circular cutterheads and forms an overlapping, interlocking circular cutterhead layout, ensuring no blind spots during excavation. This method is applicable to various geological formations, including bedrock and mixed strata, and is not limited by geological conditions, thus having broad applicability. Furthermore, a support shield is installed within the annular pre-excavation outline. The support shield advances with the circular cutterhead, providing temporary support to ensure tunnel excavation safety. The support shield also serves as a cyclical pre-support for the tunnel, advancing with the circular cutterhead, effectively making it reusable—both environmentally friendly and economical. Since multiple circular cutterheads excavate the peripheral strata, the central strata are left unexcavated. These central strata are then gradually loaded and transported out of the tunnel using simple crushing and mechanical transportation methods, and tunnel supports are then erected. This method ensures the stability of the tunnel structure, avoids mechanical excavation in the middle strata, reduces excavation energy consumption, and saves energy. At the same time, since the circular cutterhead advances the support shield simultaneously during excavation, the support shield is used as temporary support when excavating the middle strata, eliminating the need for additional temporary support and improving construction efficiency. Compared with shield tunneling or drill-and-blast methods in related technologies, the construction method of this application is applicable to various cross-sectional profiles, can excavate tunnels with various cross-sectional shapes, has wide applicability, and allows for the recycling of the support shield, making it environmentally friendly. It also ensures high excavation safety, low energy consumption during excavation of the middle strata, and high excavation efficiency.

[0009] In one possible implementation of this application, the circular cutterhead excavation face corresponding to the upper section of the tunnel advances ahead of the circular cutterhead excavation face corresponding to the lower section of the tunnel, and the length of the support shield corresponding to the upper section of the tunnel is greater than the length of the support shield corresponding to the lower section of the tunnel. The multiple circular cutterheads are arranged in a configuration where the upper part advances the lower part, creating an inclined surface at the excavation face. The lower soil layer provides some support for the upper construction equipment, thereby improving construction safety. Simultaneously, the support shield also exhibits a layout where the upper part advances the lower part, and the lower part advances the middle strata, creating an inclined surface at the excavation face. The lower soil layer provides some support for the upper construction equipment, further enhancing the safety of the construction process.

[0010] In one possible implementation of this application, in the step of using multiple circular cutterheads continuously distributed along the tunnel outline to excavate the surrounding strata, multiple circular cutterheads with the same diameter are used for excavation.

[0011] In one possible implementation of this application, in the step of using multiple circular cutterheads continuously distributed along the tunnel outline to excavate the surrounding strata, multiple circular cutterheads of different diameters are used for excavation. When the middle strata are cut laterally or to facilitate cutter replacement, a larger diameter circular cutterhead is used for excavation in the corresponding local area, while a smaller diameter circular cutterhead is used for excavation in the remaining parts.

[0012] In one possible implementation of this application, the support shields corresponding to the upper section of the tunnel and the support shields corresponding to the lower section of the tunnel have the same length, and multiple circular cutterheads are staggered front to back to form two excavation faces that are staggered front to back.

[0013] In one possible implementation of this application, during the step of advancing the support shield, the outline dimensions of the support shield and the circular cutterhead are consistent on the side closest to each other, and the outline dimension of the support shield gradually decreases along the direction away from the circular cutterhead. That is, along the tunnel excavation direction, the outline dimension of the support shield gradually increases, which is equivalent to a wedge-shaped structure. The support shield experiences less resistance during advancement, and the advancement is more stable.

[0014] In one possible implementation of this application, in the step of advancing the support shield, the support shield includes an arch-ribbed shield and an annular shield, which are arranged sequentially along the direction away from the circular cutterhead.

[0015] In one possible implementation of this application, the arch-rib shield includes two arch plates whose contours fit the annular advance excavation contour, and multiple ribs are provided between the two arch plates. The multiple ribs divide the arch-rib shield into multiple box-shaped structures, and the multiple box-shaped structures are provided in a one-to-one correspondence with multiple circular cutterheads.

[0016] In one possible implementation of this application, the annular shield's cross-sectional profile is set according to the tunnel profile, and the annular shield is located within the annular advance excavation profile and contacts the outer profile of the annular advance excavation profile. The annular shield temporarily supports the tunnel during loading and transportation in the middle strata to ensure safe loading and transportation in the middle strata.

[0017] In one possible implementation of this application, before the tunnel support erection step, segment lining or shotcrete support lining is selected as the tunnel support based on the engineering geological conditions. This ensures the stability of the support while reducing project costs.

[0018] In one possible implementation of this application, when segment lining is used as tunnel support, the construction method of segment lining includes: advancing the support shield to leave segment lining, and gradually filling the gap between segment lining and tunnel outline.

[0019] The tunnel construction method provided in this application involves advancing a support shield to leave segment lining, changing the support from shield to segment lining. During this process, the tunnel wall remains supported at all times, thus ensuring construction safety. As the support shield advances, it gradually fills the gap between the segment lining and the tunnel outline, making the support more reliable. This method is mainly used when the geological strata of the tunnel wall are unstable and insufficient to guarantee that there will be no support collapse after the support shield advances.

[0020] In one possible implementation of this application, the segment lining profile is set according to the tunnel profile.

[0021] In one possible implementation of this application, when using shotcrete support lining as tunnel support, the construction method of shotcrete support lining includes: spraying concrete after the support shield body is advanced, erecting anchor bolts, and pouring concrete lining.

[0022] In one possible implementation of this application, when excavating and loading the middle stratum out of the tunnel, the excavation sequence proceeds from the upper to the lower part of the middle stratum to form a middle stratum with a safe slope. The sloping middle stratum acts as a soil plug along the tunnel excavation direction, supporting the stratum in the excavation direction to prevent deformation and playing a certain stabilizing role.

[0023] In one possible implementation of this application, the step of loading and transporting the central strata out of the tunnel includes: crushing the rock strata in the central strata; and loading and transporting the soil and the crushed rock strata out of the tunnel.

[0024] In one possible implementation of this application, before the step of using multiple circular cutterheads continuously distributed along the tunnel outline to rotate and excavate the surrounding strata, preparatory work is also included. The preparatory work mainly includes the following steps: excavating a working shaft; placing the construction equipment into the tunnel through the working shaft; and assembling the construction equipment inside the tunnel. Attached Figure Description

[0025] Figure 1 A flowchart of a method for constructing a cut-and-cover tunnel provided in an embodiment of this application;

[0026] Figure 2 This is a schematic diagram of the geological structure;

[0027] Figure 3 When using segment lining Figure 2 Sectional view of section AA;

[0028] Figure 4 When using anchor-sprayed lining Figure 2 Sectional view of section AA;

[0029] Figure 5 A schematic diagram showing the staggered arrangement of circular cutter heads;

[0030] Figure 6 This is a schematic diagram of the outline of the ring-shaped advance excavation.

[0031] Figure 7 A flowchart illustrating the preparation process for the tunnel excavation method provided in this application embodiment;

[0032] Figure 8 Schematic diagrams showing the construction process using circular cutterheads of different diameters;

[0033] Figure 9 for Figure 3 Sectional view of section BB;

[0034] Figure 10 for Figure 3 Sectional view of section C-C;

[0035] Figure 11 This is a schematic diagram showing the dimensions of the ring-shaped shield.

[0036] Figure 12 A flowchart illustrating the excavation of the middle strata in the tunnel construction method provided in this application embodiment.

[0037] Figure label:

[0038] 1-Geological structure; 11-Surrounding strata; 12-Central strata; 13-Annular advance excavation outline; 2-Construction equipment; 21-Circular cutterhead; 211-Upper cutterhead; 212-Lower cutterhead; 22-Support shield; 221-Arch-rib shield; 2211-Arch plate; 2212-Rib plate; 222-Annular shield; 23-Tunnel support; 231-Segment lining; 232-Anchor-sprayed support lining; 3-Upper advance distance; 4-Lower advance distance. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the specific technical solutions of this application will be further described in detail below with reference to the accompanying drawings of the embodiments of this application. The following embodiments are used to illustrate this application, but are not intended to limit the scope of this application.

[0040] In the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more.

[0041] Furthermore, in the embodiments of this application, directional terms such as "upper," "lower," "left," and "right" are defined relative to the positions in which the components are schematically placed in the accompanying drawings. It should be understood that these directional terms are relative concepts, used for relative description and clarification, and can change accordingly depending on the position of the components in the accompanying drawings.

[0042] In the embodiments of this application, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium.

[0043] In embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0044] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0045] This application provides a method for constructing a tunnel by cut-and-cover method, which can be applied to the construction of tunnels by cut-and-cover method, especially shallow-buried tunnels such as municipal tunnels, railway tunnels, and subway stations.

[0046] Reference Figure 1 The method for constructing a cut-and-cover tunnel in this application mainly includes the following steps:

[0047] S1: Reference Figure 2 , Figure 3 and Figure 4 Multiple circular cutterheads 21, continuously distributed along the tunnel outline, are used to rotate and excavate the surrounding strata 11, forming a ring-shaped advance excavation outline 13, as shown in the reference. Figure 5 Multiple circular cutterheads 21 are arranged alternately along the tunnel outline, and adjacent circular cutterheads 21 are staggered in front and behind along the tunnel excavation direction. A support shield 22 is provided in the annular advance excavation outline 13. The support shield 22 advances with the circular cutterheads 21 to serve as the cyclic advance support of the tunnel.

[0048] S2: Under the protection of the support shield 22, excavate the middle stratum 12 and load and transport it out of the tunnel, and erect the tunnel support 23.

[0049] Among them, reference Figure 2 The geological structure 1 to be excavated can be divided into two parts: the peripheral stratum 11 and the central stratum 12. The central stratum 12 is inside the peripheral stratum 11. In step S1, the circular cutterhead 21 excavates in the peripheral stratum 11, leaving the central stratum 12, and the support shield 22 advances closely following the circular cutterhead 21 as it excavates.

[0050] Multiple circular cutterheads 21, continuously distributed along the tunnel outline, are used to excavate the surrounding strata 11, creating multiple circular excavation outlines continuously distributed along the tunnel outline. (Refer to...) Figure 2 and Figure 6 Multiple circular excavation profiles are connected to form an annular excavation profile. Since the circular cutterhead 21 excavates the surrounding strata 11, this annular excavation profile precedes the excavation profile of the central strata 12. Because this annular leading excavation profile 13 is formed by combining multiple continuously distributed circular excavation profiles, the tunnel profile is not limited by the profile of the tunneling machinery, i.e., the circular cutterhead 21. The construction method of this application can excavate tunnels with circular cross-sections as well as tunnels with non-circular cross-sections, such as elliptical cross-section tunnels and square tunnels. (Refer to...) Figure 2 and Figure 6 In one embodiment of this application, multiple excavation faces are connected to form an elliptical annular advance excavation profile 13, that is, the cross-section of the excavated tunnel is elliptical. Excavation is carried out according to the tunnel profile based on construction requirements to avoid over-excavation and waste of energy.

[0051] Meanwhile, the excavation profile excavated by a single circular cutterhead 21 is relatively small compared to the overall tunnel profile area, resulting in less disturbance to the strata during excavation and simpler support, facilitating the construction of shallow overburden tunnels. Furthermore, multiple circular cutterheads 21 are arranged alternately along the tunnel profile, with adjacent circular cutterheads 21 staggered along the tunnel excavation direction. This avoids interference between adjacent circular cutterheads 21 and creates an overlapping, interlocking layout, eliminating blind spots during excavation. It is applicable to composite strata, bedrock strata, and other geological formations, and the construction method of this application is not limited by geological conditions, exhibiting wide applicability. The multiple circular cutterheads 21 can be divided into multiple groups for group control during excavation, or all circular cutterheads 21 can be connected as a whole for unified advancement during construction.

[0052] In addition, a support shield 22 is set within the annular advance excavation outline 13. During the excavation of the circular cutterhead 21, the support shield 22 is advanced closely behind. The support shield 22 plays a temporary support role to ensure the safety of tunnel excavation operations. Moreover, the support shield 22 serves as a cyclic advance support for the tunnel, advancing with the circular cutterhead 21, which is equivalent to repeated use, making it both green and economical.

[0053] Reference Figure 3 and Figure 4 Since the multiple circular cutterheads 21 excavate the surrounding strata 11, the central strata 12 located in the middle is left behind. Then, the central strata 12 is gradually loaded and transported out of the tunnel using simple crushing and mechanical transportation methods. Tunnel support 23 is then erected to ensure the stability of the tunnel structure, avoiding mechanical excavation of the central strata 12, reducing excavation energy consumption, and saving energy. At the same time, since the circular cutterheads 21 advance the support shield 22 at the same time as excavation, the support shield 22 is used as a temporary support when excavating the central strata 12, eliminating the need for additional temporary support and improving construction efficiency.

[0054] Compared with shield tunneling or drill-and-blast methods in related technologies, the construction method of this application is applicable to various strata and can excavate tunnels with various cross-sectional shapes, which has wide applicability. Furthermore, the support shield 22 is recyclable, which is green and environmentally friendly. The tunneling process is safe and secure, and the energy consumption for excavating the middle stratum 12 is low, with high tunneling efficiency.

[0055] Since the tunnel excavation direction is relatively horizontal, a relatively vertical working shaft needs to be excavated before tunnel excavation to assemble the construction equipment 2 extending along the tunnel excavation direction within the working shaft. Therefore, referring to... Figure 7 In one embodiment of this application, prior to the step of using multiple circular cutterheads 21 continuously distributed along the tunnel contour to rotate and excavate the surrounding strata 11, the method further includes:

[0056] S0: Preparations.

[0057] Preparation work S0 mainly includes the following steps:

[0058] S01: Excavation of the working shaft;

[0059] S02: Lower construction equipment 2 into the tunnel from the working shaft;

[0060] S03: Assemble construction equipment 2 inside the tunnel.

[0061] It should be noted that in step S1, the excavation progress of the multiple circular cutterheads 21 is not the same. For example, in one embodiment of this application, the multiple circular cutterheads 21 are staggered to form two excavation faces that are staggered. That is, the multiple circular cutterheads 21 are divided into two groups, and the two groups of circular cutterheads 21 are distributed at intervals. Along the tunnel excavation direction, one group of circular cutterheads 21 is in front, and the other group of circular cutterheads 21 is slightly behind. That is, during construction, the multiple circular cutterheads 21 are staggered along the tunnel excavation direction. Correspondingly, the length of the support shield 22 corresponding to the upper section of the tunnel and the support shield 22 corresponding to the lower section of the tunnel are the same.

[0062] To improve the stability of the excavated tunnel and ensure construction safety, refer to Figure 3 and Figure 4 In one embodiment of this application, the excavation face of the circular cutterhead 21 corresponding to the upper section of the tunnel is ahead of the excavation face of the circular cutterhead 21 corresponding to the lower section of the tunnel. The multiple circular cutterheads 21 are in a state where the upper part is ahead of the lower part, so that the excavation face forms an inclined surface. The soil layer below can provide certain support for the construction equipment above, thereby improving the safety of construction.

[0063] Based on this, in order to improve construction safety, refer to Figure 3 and Figure 4 In one embodiment of this application, the length of the support shield 22 corresponding to the upper section of the tunnel is greater than the length of the support shield 22 corresponding to the lower section of the tunnel. The support shield 22 has an overall layout where the upper part of the support shield 22 leads the lower part, and the lower part of the support shield 22 leads the middle stratum 12. This creates an inclined surface at the excavation face, and the lower soil layer can provide some support for the upper construction equipment 2, making the construction process safer. The specific leading distance can be determined according to the actual construction conditions, referring to... Figure 3 and Figure 4 Different advance distances are set according to different strata, with the upper advance distance 3 being greater than the lower advance distance 4.

[0064] Furthermore, in step S1, the circular cutterhead 21 can have various circular outline dimensions, such as circular cutterheads 21 with diameters of 70cm or 80cm. It should be noted that in the step where multiple circular cutterheads 21 continuously distributed along the tunnel outline each rotate to excavate the surrounding strata 11, the circular outline dimensions of the circular cutterheads 21 can be the same or different. (Refer to...) Figure 2 In one embodiment of this application, multiple small-sized circular cutterheads 21 with the same diameter are used to excavate and form an annular advance excavation profile 13, as shown in the reference. Figure 6 In another embodiment of this application, multiple large-sized circular cutterheads 21 with the same diameter are used to excavate and form an annular advance excavation profile 13. The size of the circular cutterheads 21 can be selected mainly based on the strength of the support shield 22, the soil removal method of the middle stratum 12, etc.

[0065] To save on project costs, the circular cutterhead 21 used during construction can be selected in different sizes according to requirements, as shown in the reference. Figure 8 In one embodiment of this application, in step S1, multiple circular cutterheads 21 continuously distributed along the tunnel outline are used to excavate the surrounding strata. Multiple circular cutterheads 21 of different diameters are used to form an annular advance excavation outline 13. Specifically, this includes three larger diameter circular cutterheads 21 and multiple smaller diameter circular cutterheads 21, with the three larger diameter circular cutterheads 21 evenly distributed among the multiple smaller diameter circular cutterheads 21. When the middle strata 12 is cut laterally or to facilitate cutter replacement, the larger diameter circular cutterheads 21 are used for excavation in the corresponding local area, while the smaller diameter circular cutterheads 21 are used for excavation in the remaining parts. This reduces the equipment cost of the circular cutterheads 21 and saves on engineering expenses.

[0066] In step S1, the support shield 22 needs to advance synchronously with the circular cutterhead 21. To facilitate the advancement of the support shield 22, in one embodiment of this application, the outline dimensions of the support shield 22 and the circular cutterhead 21 on the side closest to each other are the same, so as to avoid the tunnel wall forming resistance on the front end face of the support shield 22. At this time, the dimensions of the support shield 22 along its own extension direction can be the same or different. In order to facilitate the advancement of the support shield 22, the outline dimension of the support shield 22 gradually decreases along the direction away from the circular cutterhead 21, that is, along the tunnel excavation direction, the outline dimension of the support shield 22 gradually increases, which is equivalent to a wedge structure. The support shield 22 experiences less resistance when advancing, and the advancement is more stable.

[0067] In step S1, the support shield 22 serves a supporting and protective function. As the central stratum 12 is excavated, the stress and requirements inside the support shield 22 differ depending on whether the central stratum 12 section is present or not. Therefore, various types of support shields 22 need to be installed according to local conditions. (Refer to...) Figure 3 and Figure 4 In one embodiment of this application, the support shield 22 includes an arch-rib shield 221 and an annular shield 222. The arch-rib shield 221 is installed in the tunnel section with the central stratum 12, which can effectively support the annular advanced excavation profile 13 with the help of the central stratum 12. The annular shield 222 is installed in the tunnel section without the central stratum 12, and supports the tunnel profile when the central stratum 12 is excavated.

[0068] The arch-ribbed shield 221 can have various structures, and any structure that can support the annular advance excavation profile 13 is within the protection scope of this application. Considering the structural strength and engineering cost of the arch-ribbed shield 221, refer to... Figure 9 In one embodiment of this application, the arch-rib shield 221 includes two arch plates 2211 whose contours fit the annular advance excavation contour 13. Multiple ribs 2212 are provided between the two arch plates 2211. The ribs 2212 can provide good support, thereby increasing the strength of the arch-rib shield 221 and ensuring construction safety. The multiple ribs 2212 divide the arch-rib shield 221 into multiple box-shaped structures. The multiple box-shaped structures are arranged one-to-one with multiple circular cutterheads 21 to correspond to the annular advance excavation contour 13.

[0069] Based on this, when excavating the central stratum 12, it is also necessary to support the tunnel outline to prevent the central stratum 12 from collapsing and to ensure construction safety, referring to... Figure 3 and Figure 4 In one embodiment of this application, the annular shield 222 is installed in the tunnel section without the central stratum 12, and supports the tunnel outline during the excavation of the central stratum 12.

[0070] The outline of the annular shield can take various forms, such as resembling the annular pre-excavation outline 13, or resembling the tunnel outline, etc., as shown in the reference. Figure 10 and Figure 11 In one embodiment of this application, the cross-sectional profile of the annular shield 222 is set according to the tunnel profile, and the annular shield 222 is located within the annular advanced excavation profile 13. The annular shield 222, which is made according to the tunnel profile, ensures safe loading and transportation of the middle stratum 12 and facilitates the advancement and connection of the annular shield 222.

[0071] The annular shield 222 can take various forms. Any structure that can support the tunnel during the excavation of the central stratum 12 and can advance along the tunnel excavation direction is within the protection scope of this application. (Refer to...) Figure 10 and Figure 11In one embodiment of this application, the annular shield 222 is a ring-shaped structure set along the tunnel outline. This structure can be integrally formed or segmented and spliced. The annular shield 222 is a solid structure, and its thickness is less than that of the arch-rib shield 221. It should be noted that the annular shield 222 is in contact with the outer outline of the annular advance excavation outline 13. That is, the annular shield 222 should be set as far away from the central stratum 12 as possible so that tunnel support 23 can be set inside it later.

[0072] To ensure the structural strength of the support shield 22, both the arch-rib shield 221 and the ring shield 222 are made of steel.

[0073] After the support shield 22 advances with the circular cutterhead 21, a central stratum 12 is left behind. This central stratum 12 needs to be removed from the tunnel for subsequent tunnel construction. To improve construction safety, refer to... Figure 3 and Figure 4 In one embodiment of this application, in step S2 of excavating the middle stratum 12 and loading it out of the tunnel, the excavation sequence proceeds from the upper part to the lower part of the middle stratum 12 to form a middle stratum 12 with a safe slope. The safe slope is a slope range calculated based on the construction site conditions. Generally, the smaller the slope, the higher the safety. The middle stratum 12 with a slope provides support to the stratum in front, equivalent to the soil plug in the drill-and-blast method. It can ensure the safety of the supporting face in front, suppress the deformation of the stratum in the excavation direction, and play a certain supporting role, thereby further ensuring the safety of construction.

[0074] To facilitate the loading and removal of the central stratum 12, refer to Figure 12 In one embodiment of this application, the step of loading and transporting the middle stratum 12 out of the tunnel includes:

[0075] S21: The rock strata in the central stratum 12 are broken up;

[0076] S22: Load and transport the soil and broken rock strata out of the tunnel.

[0077] After the rock strata were broken into smaller pieces, they were easier to load and took up less space during transport. At the same time, more debris could be transported out, improving the transport efficiency of the central stratum 12.

[0078] Based on this, due to different engineering geological conditions, the corresponding tunnel support requirements 23 are not the same. Considering the reliability of the support and the project cost, before the tunnel support erection step S2, the following are included:

[0079] S23: Select either segment lining 231 or shotcrete support lining 232 as tunnel support 23 based on engineering geological conditions. Specifically, when the strata of the tunnel wall are unstable and insufficient to ensure that the tunnel collapses due to lack of support after the annular shield 222 is advanced, segment lining 231 is selected as tunnel support 23 to ensure construction safety. In addition, when the strata are relatively stable and the strata around the unsupported tunnel can stabilize itself, shotcrete support lining 232 can be selected as tunnel support 23 to ensure tunnel stability and reduce construction costs.

[0080] When segment lining 231 is selected as tunnel support 23, refer to Figure 12 The construction methods for installing segment lining 231 mainly include:

[0081] S24: Advance the annular shield 222 to leave the segment lining 231 and gradually fill the gap between the tunnel outline and the segment lining 231.

[0082] It should be noted that before advancing the annular shield 222, the segment lining 231 needs to be assembled inside the annular shield 222. After the segment lining 231 is assembled and can play a supporting role, the annular shield 222 is advanced, and the support changes from the annular shield 222 to the segment lining 231. During this process, the tunnel wall remains supported at all times, thus ensuring the safety of construction. As the annular shield 222 advances, it gradually fills the gap between the tunnel outline and the segment lining 231, making the connection between the tunnel wall and the segment lining 231 tighter and the stress more balanced. This reduces the disturbance of the tunnel wall rock strata caused by the advancement of the annular shield 222, and also ensures that there are no gaps between the segment lining 231 and the tunnel wall, making the support more reliable. It should be noted that, in order to facilitate the connection between the annular shield 222 and the segment lining 231, the combined cross section of the two should be within the annular advance excavation outline 13 and as smooth as possible to facilitate structural stress and improve the reliability of the support.

[0083] It should be noted that the construction method of this application can be applied to tunnel profiles of various shapes. Therefore, the profile of the segment lining 231 should also be set according to the tunnel profile so that the segment lining 231 and the tunnel being constructed can be well adapted.

[0084] When anchor-sprayed lining 232 is selected as tunnel support 23, refer to Figure 12 In one embodiment of this application, the construction method of the anchor-sprayed lining 232 includes:

[0085] S25: After the support shield 222 is advanced, shotcrete is applied, anchor bolts are installed, and concrete lining is poured. The concrete and anchor bolt support scheme provides good support for the tunnel, and because the scheme is simple and easy to implement, it saves on tunnel construction costs.

[0086] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made based on the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method of tunneling, characterized by, The method comprises the following steps: The step of excavating the peripheral stratum by rotating a plurality of circular cutters continuously distributed along the tunnel contour comprises excavating the peripheral stratum by rotating a plurality of circular cutters with consistent diameters. The step of excavating the peripheral stratum by rotating a plurality of circular cutters continuously distributed along the tunnel contour comprises excavating the peripheral stratum by rotating a plurality of circular cutters with different diameters.

2. The tunneling method according to claim 1, wherein In the step of advancing the supporting shield, the contour size of the side of the supporting shield close to the circular cutter is consistent with the contour size of the circular cutter, and the contour size of the supporting shield gradually decreases in the direction away from the circular cutter.

3. The tunneling method according to claim 1, wherein In the step of advancing the supporting shield, the supporting shield comprises an arch-rib type shield and a ring type shield, and the arch-rib type shield and the ring type shield are sequentially arranged in the direction away from the circular cutter.

4. The tunneling method according to claim 1, wherein The arch-rib type shield comprises two arch plates with contours matching the annular advanced excavation contour, and a plurality of rib plates are arranged between the two arch plates, the plurality of rib plates separate the arch-rib type shield into a plurality of box type structures, and the plurality of box type structures are arranged one-to-one corresponding to the plurality of circular cutters.

5. The tunneling method according to claim 4, wherein The cross-sectional contour of the ring type shield is arranged according to the tunnel contour, and the ring type shield is located in the annular advanced excavation contour and in contact with the outer contour of the annular advanced excavation contour.

6. The tunneling method according to claim 5, wherein Before the step of erecting the tunnel support, the pipe segment lining or the anchor shotcrete support lining is selected as the tunnel support according to the engineering geological conditions.

7. The tunneling method according to claim 5, wherein When the pipe segment lining is used as the tunnel support, the construction method of the pipe segment lining comprises: advancing the supporting shield to leave the pipe segment lining and gradually filling the gap between the pipe segment lining and the tunnel contour.

8. The tunneling method according to claim 1, wherein The contour of the pipe segment lining is arranged according to the tunnel contour.

9. The tunneling method according to claim 8, wherein When the anchor shotcrete support lining is used as the tunnel support, the construction method of the anchor shotcrete support lining comprises: spraying concrete, erecting anchor rods and pouring concrete lining after the supporting shield is advanced.

10. The tunneling method according to claim 8 or 9, wherein When the middle stratum is excavated and loaded out of the tunnel, the excavation is sequentially performed from the upper part to the lower part of the middle stratum to form the middle stratum with a safe slope.

11. The tunneling method according to claim 8, wherein The step of loading the middle stratum out of the tunnel comprises:

12. The tunneling method according to claim 1, wherein crushing the rock stratum in the middle stratum; 13. The tunneling method according to claim 1, wherein loading the soil and the crushed rock stratum out of the tunnel. ​ ​ 14. The method of claim 1, wherein, Before the step of excavating the peripheral ground by rotating the plurality of circular cutters, there are preparatory steps, which mainly include the following steps: Excavating a work shaft; Putting the construction equipment into the tunnel from the work shaft; Assembling the construction equipment in the tunnel.

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