Tunnel lining dismantling expanding excavation construction method

Abstract

The invention discloses a tunnel lining dismantling and expanding excavation construction method, which relates to the technical field of tunnel construction, and comprises the following specific steps: step 1, firstly carrying out one-by-one circumferential cutting on a tunnel lining structure along a tunnel center line by using a cutting process, and then carrying out longitudinal cutting on the basis of the circumferential cutting so as to form a plurality of block-shaped area structures; 2, in the longitudinal cutting process, a temporary supporting structure is additionally arranged on the lining structure to support and reinforce the lining structure; 3, block-shaped area structures formed after the lining structure is subjected to annular cutting and longitudinal cutting are synchronously dismantled one by one; and 4, tunnel expanding excavation is conducted according to different blocky area structures. According to the method, annular cutting is conducted firstly, then longitudinal cutting is conducted, the existing lining structure is dismantled in an annular cutting and partitioning mode, the advantages of a lining arch structure are effectively utilized to form effective supporting on a rock-soil body, and therefore the construction safety is improved.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a method for tunnel lining removal and excavation. Background Technology

[0002] Tunnels are engineering structures buried underground, representing a form of human utilization of underground space. Tunnels can be categorized into traffic tunnels, hydraulic tunnels, municipal tunnels, mining tunnels, and military tunnels.

[0003] As tunnels age, problems such as lining deformation, material deterioration, and severe load-bearing capacity arise, affecting tunnel safety and necessitating replacement of the original lining structure. Furthermore, with rapid societal development, some tunnels can no longer meet current and future traffic demands, requiring in-situ reconstruction and expansion. Both tunnel lining replacement and reconstruction / expansion involve the challenging tasks of demolishing the existing tunnel lining structure and widening the excavation of the new tunnel.

[0004] After tunnel construction, the surrounding rock and structure are in a relatively stable equilibrium state. Removing the lining at this point will unload the stable surrounding rock, leading to a redistribution of ground stress. Stress distribution and deformation are complex processes that affect construction safety. During construction, the surrounding rock is repeatedly disturbed due to numerous procedures, and the support structure experiences variable stress, making it highly susceptible to problems such as surrounding rock instability and cracking of the tunnel lining structure. This poses significant safety risks during tunnel widening and excavation. Therefore, we propose a method for tunnel lining removal and widening construction. Summary of the Invention

[0005] The purpose of this invention is to provide a method for tunnel lining removal and excavation to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for tunnel lining removal and excavation, comprising the following specific steps:

[0007] Step 1: First, the tunnel lining structure is cut circumferentially along the tunnel centerline using a cutting process. Then, based on the circumferential cutting, longitudinal cutting is performed to form multiple block-shaped regional structures.

[0008] Step 2: During the longitudinal cutting process, temporary support structures are added to the lining structure to support and reinforce it.

[0009] Step 3: Simultaneously dismantle the block-shaped structures formed by circumferential and longitudinal cutting of the lining structure.

[0010] Step 4: Expand the tunnel for different blocky area structures.

[0011] Preferably, step 1 specifically includes:

[0012] Step 1.1: Use a hydraulic cutting machine for secondary lining concrete to make circumferential cuts at intervals, thereby dividing a lining unit into multiple segments, and then make longitudinal cuts.

[0013] Step 1.2: After circumferential and longitudinal cutting, different blocky regional structures will be formed, and the blocky regional structures are successively divided into Zone I, Zone II, Zone III, Zone IV and Zone V. Temporary support structures are added to support different blocky regions. Among them, the surrounding rock of different lining sections in Zones III, IV and V is further divided into Type a and Type b.

[0014] Preferably, step 1.2 specifically includes:

[0015] During the construction of Zone I, a hydraulic cutter for the secondary lining concrete was first used to cut the No. 1 joint, then the No. 2 joint, and finally the No. 3 joint. The No. 1 and No. 2 joints were staggered by a distance from the outer edge of the temporary support during construction.

[0016] Preferably, step 1.2 further includes:

[0017] First, a hydraulic cutting machine for secondary lining concrete is used to cut the IVb and IVa lining sections circumferentially. Then, longitudinal sections are cut separately, and support structures are added to the IVa and IVb lining sections.

[0018] Preferably, step 1.2 further includes:

[0019] During construction, a hydraulic cutting machine for secondary lining concrete is first used to cut the lining sections in a circumferential manner according to the type IIIa and type IIIb lining sections, and then the sections are cut longitudinally.

[0020] Preferably, step 4, for the widening excavation of the type V lining section, has the following specific steps:

[0021] Step 4.1.a: After constructing the tunnel pre-support, the original tunnel secondary lining and the lower half of the tunnel section were enlarged and temporary support structures were added. Then, sandbags were used to backfill to the tunnel arch position.

[0022] Step 4.2.a: In sequence, demolish the original tunnel lining structure of the upper step of the left pilot tunnel, the lower step of the left pilot tunnel, the upper step of the middle pilot tunnel, the upper step of the right pilot tunnel, the lower step of the middle pilot tunnel, and the lower step of the right pilot tunnel. After each demolition, excavate and widen the tunnel according to the new tunnel outline, and construct the corresponding initial support and temporary support structures.

[0023] Step 4.3.a: Remove the vertical temporary supports, pour the secondary lining of the invert arch and backfill the invert arch, lay the waterproof membrane, and use a formwork trolley to pour the secondary lining concrete of the arch wall.

[0024] Preferably, step 4, for the widening excavation of the type IV lining section, has the following specific steps:

[0025] Step 4.1.b: Construct tunnel pre-support, then construct the original tunnel secondary lining and add temporary support structure to the lower half of the tunnel section, and then backfill with sandbags to the tunnel arch position.

[0026] Step 4.2.b: In sequence, dismantle the original tunnel lining structure of the upper step of the left guide tunnel, the original tunnel lining structure of the lower step of the left guide tunnel, the original tunnel lining structure and secondary lining steel pipe support of the upper step of the right guide tunnel, the original tunnel lining structure and secondary lining temporary support of the middle step of the right guide tunnel, and the original tunnel lining structure of the lower step of the right guide tunnel. After each dismantling, excavate and widen the tunnel according to the new tunnel outline, and construct the corresponding initial support and temporary support structure. Then repeat the above steps to advance the tunnel.

[0027] Step 4.3.b: Remove temporary supports, pour the secondary lining of the invert arch and backfill the invert arch, lay waterproof membrane, and use a formwork trolley to pour the secondary lining concrete of the arch wall.

[0028] Preferably, step 4, for the widening excavation of the type IIIa lining section, has the following specific steps:

[0029] Step 4.1.c: Remove the original tunnel lining structure of the upper bench, and widen the excavation according to the new tunnel outline, and construct the initial support for the upper bench;

[0030] Step 4.2.c: Remove the original tunnel lining structure on the left side of the lower step, expand the excavation according to the new tunnel outline, and construct the initial support;

[0031] Step 4.3.c: Remove the original tunnel lining structure on the right side of the lower step, expand the excavation according to the new tunnel outline, and construct the initial support.

[0032] Preferably, step 4, for the widening excavation of the type IIIb lining section, has the following specific steps:

[0033] Step 4.1.d: Construct the secondary lining diagonal bracing of the original tunnel, and then backfill with stone ballast to form an operating platform;

[0034] Step 4.2.d: In sequence, dismantle the original tunnel lining structure of the upper step, the temporary diagonal bracing of the secondary lining on the left side of the middle step and the original tunnel lining structure, the temporary diagonal bracing of the secondary lining on the middle step and the original tunnel lining structure on the right side, the original tunnel lining structure on the left side of the lower step and the original tunnel lining structure on the right side of the lower step. After each dismantling, excavate and widen the tunnel according to the new tunnel outline, and construct the corresponding initial support and temporary support structures. Then repeat the above steps to advance the tunnel.

[0035] Preferably, the temporary support structure adopts two forms: I-beams and steel pipe columns, and the tunnel space is backfilled after the temporary support structure is added.

[0036] The technical effects and advantages of this invention are as follows:

[0037] 1. This invention first performs circumferential cutting, then longitudinal cutting. The existing lining structure is dismantled in sections by circumferential cutting, which effectively utilizes the advantages of the arched structure of the lining to provide effective support to the rock and soil. At the same time, temporary support structures are added simultaneously during the dismantling process to support the tunnel lining, thereby improving the safety of construction.

[0038] 2. This invention cuts the tunnel lining piece by piece through circumferential and longitudinal cutting, while simultaneously supporting it, and then backfilling it, thereby maintaining the stability of the tunnel lining structure. Subsequently, it is demolished and gradually excavated, thereby reducing the impact of unloading on the stable surrounding rock, improving construction safety, and reducing disturbance to the surrounding rock by constructing according to the predetermined procedures, thus lowering the probability of surrounding rock instability and cracking and damage to the tunnel lining structure. Attached Figure Description

[0039] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0040] Figure 1 This is a plan view of the lining cutting of the present invention;

[0041] Figure 2 This is a cross-sectional view of the lining cut according to the present invention;

[0042] Figure 3 This is a schematic diagram of the block-shaped region structure of the present invention;

[0043] Figure 4 This is a schematic diagram of step 1 of the specific process of widening the excavation of the V-type lining section in step 4 of the present invention;

[0044] Figure 5 This is a schematic diagram of step 2 of the specific process of widening the excavation of the type V lining section in step 4 of the present invention;

[0045] Figure 6 This is a schematic diagram of step 3 of the specific process of widening the excavation of the type V lining section in step 4 of the present invention;

[0046] Figure 7 This is a schematic diagram of the structure of step 4 of the present invention, which is a specific process for widening the excavation of the type V lining section;

[0047] Figure 8This is a schematic diagram of step 5 of the specific process of widening the excavation of the V-type lining section in step 4 of the present invention;

[0048] Figure 9 This is a schematic diagram of step 6 of the specific process of widening the excavation of the V-type lining section in step 4 of the present invention;

[0049] Figure 10 This is a schematic diagram of step 7 of the specific process of widening the excavation of the V-type lining section in step 4 of the present invention;

[0050] Figure 11 This is a schematic diagram of step 8 of the specific process of widening the excavation of the V-type lining section in step 4 of the present invention. Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] This invention provides, for example Figures 1-11 The tunnel lining removal and widening construction method shown includes the following specific steps:

[0053] Step 1: First, the tunnel lining structure is cut circumferentially along the tunnel centerline using a cutting process. Then, based on the circumferential cutting, longitudinal cutting is performed to form multiple block-shaped regional structures.

[0054] Step 2: During the longitudinal cutting process, temporary support structures are added to the lining structure to support and reinforce it.

[0055] Step 3: Simultaneously dismantle the block-shaped structures formed by circumferential and longitudinal cutting of the lining structure.

[0056] Step 4: Expand the tunnel for different blocky area structures.

[0057] The demolition of existing lining structures and the excavation of new tunnels follow the principles and construction sequence of "short cutting, strong reinforcement, rapid backfilling, slow demolition, rapid closure, and frequent measurement." The demolition of existing lining structures employs ring-shaped cutting in sections, effectively utilizing the advantages of the arched lining structure to provide effective support to the soil and rock mass. The cutting method avoids disturbance to the strata caused by blasting. Combining traditional tunnel construction techniques such as double-sided pilot tunnels, CD (cab), and upper and lower bench methods, a method for tunnel expansion is proposed.

[0058] Furthermore, the temporary support structure employs both I-beams and steel pipe columns, and after adding the temporary support structure, the tunnel space is backfilled; 18-inch I-beams are used. Steel pipes, 28a channel steel, 15mm thick steel plates, supporting hydraulic system, double I20b I-beam crossbeams, etc. The steel pipes were installed in sections, and mobile temporary support frames were fabricated using 18-inch I-beams to assist in the installation. The high-strength expansion bolts connecting the upper and lower sections were completed manually. Each unit of the steel arch frame and temporary support was welded together from I-beams and connecting plates, and the units were connected by bolts. Steel pipes are installed every 5 meters, with two pipes per lining section. A double-panel I20b I-beam crossbeam is installed between the two pipes. After temporary reinforcement is completed, the tunnel space is backfilled to balance the external pressure during demolition and excavation.

[0059] Furthermore, the specific details of step 1 are as follows:

[0060] Step 1.1: Use a hydraulic cutting machine for secondary lining concrete to make circumferential cuts at intervals, thereby dividing a lining unit into multiple segments, and then make longitudinal cuts.

[0061] Step 1.2: After circumferential and longitudinal cutting, different blocky regional structures will be formed, and the blocky regional structures are successively divided into Zone I, Zone II, Zone III, Zone IV and Zone V. Temporary support structures are added to support different blocky regions. Among them, the surrounding rock of different lining sections in Zones III, IV and V is further divided into Type a and Type b.

[0062] Furthermore, the specific content of step 1.2 is as follows: When constructing Zone I, first use a hydraulic cutting machine for secondary lining concrete to cut the No. 1 joint, then cut the No. 2 joint, and finally cut the No. 3 joint. When constructing the No. 1 and No. 2 joints, stagger them by a certain distance from the outer edge of the temporary support.

[0063] First, a hydraulic cutter for the secondary lining concrete is used to cut circumferentially every 0.5m (dividing one lining unit into 10-20 segments). Then, longitudinal cutting is performed in sections. In Zone I, the No. 1 cut is made first, followed by the No. 2 cut, and finally the No. 3 cut. During cutting, care must be taken to ensure a smooth connection between the temporary H-beams and the initial support after widening the excavation; therefore, the No. 1 and No. 2 cuts are staggered by 10cm from the outer edge of the temporary support. When dismantling Zone III, cutting is performed at the No. 4 cut, but the inner reinforcing mesh should not be cut to ensure safety during dismantling.

[0064] Furthermore, step 1.2 also includes the following: First, a hydraulic cutting machine for secondary lining concrete is used to cut the IVb and IVa lining sections circumferentially, and then longitudinal sections are cut in sections. Support structures are added to the IVa and IVb lining sections.

[0065] During construction, a hydraulic cutter for the secondary lining concrete was first used to make circumferential cuts every 0.5m for type IVb lining sections and every 0.8m for type IVa lining sections. Then, longitudinal section cutting was performed. The temporary steel supports for type IVa lining sections were spaced 0.8m apart, and for type IVb lining sections, 0.5m apart. In Zone I, the No. 1 cut was made first, followed by the No. 2 cut, and finally the No. 3 cut. During cutting, care was taken to ensure a smooth connection between the temporary H-beams and the initial support after excavation; therefore, the No. 1 and No. 2 cuts were staggered by 10cm from the outer edge of the temporary supports. In Zone III, cutting was performed at the No. 4 cut, but the inner steel mesh was not cut to ensure safety during demolition. The specific longitudinal cutting positions and quantities could be adjusted during construction to improve demolition efficiency while ensuring safety.

[0066] Furthermore, step 1.2 also includes the following: during construction, a hydraulic cutting machine for secondary lining concrete is first used to cut the lining sections of type IIIa and type IIIb in a circumferential manner, and then the sections are cut longitudinally.

[0067] During construction, a hydraulic cutter for the secondary lining concrete is first used to cut circumferentially every 1.5m for type IIIa lining sections and every 1m for type IIIb lining sections. Then, longitudinal cutting is performed in sections. For type IIIb lining sections in construction zone I, the cutting sequence of the seams at positions 1 or 2 is determined, and the cutting sequence for type IIIa lining sections follows the same procedure. The specific longitudinal cutting positions can be adjusted during construction to improve demolition efficiency while ensuring safety.

[0068] Furthermore, the specific steps for the widening excavation of the type V lining section in step 4 are as follows:

[0069] Step 4.1.a: After constructing the tunnel pre-support, the original tunnel secondary lining and the lower half of the tunnel section were enlarged and temporary support structures were added. Then, sandbags were used to backfill to the tunnel arch position.

[0070] Step 4.2.a: In sequence, demolish the original tunnel lining structure of the upper step of the left pilot tunnel, the lower step of the left pilot tunnel, the upper step of the middle pilot tunnel, the upper step of the right pilot tunnel, the lower step of the middle pilot tunnel, and the lower step of the right pilot tunnel. After each demolition, excavate and widen the tunnel according to the new tunnel outline, and construct the corresponding initial support and temporary support structures.

[0071] Step 4.3.a: Remove the vertical temporary supports, pour the secondary lining of the invert arch and backfill the invert arch, lay the waterproof membrane, and use a formwork trolley to pour the secondary lining concrete of the arch wall.

[0072] Step 4, the specific process for widening the excavation of the type V lining section, is as follows:

[0073] Step 1: (1) Construct tunnel advance support; (2) Construct the original tunnel secondary lining steel pipe support N11 and the temporary support N2, temporary support N10 and temporary support N5 for the lower half section of the excavated tunnel; (3) Use sandbags to backfill to the tunnel arch waist position, requiring the backfill to be compacted.

[0074] Step 2: (1) Remove the original tunnel lining structure of the upper step of the left guide tunnel and excavate and expand it according to the new tunnel outline; (2) Construct the initial support (install steel arch frame, hang steel mesh, spray concrete and install anchor rods) and temporary support (install temporary horizontal brace N7, vertical brace N1, hang steel mesh and spray concrete) of the upper step of the left guide tunnel; (3) Repeat the above steps to advance.

[0075] Step 3: (1) Remove the original tunnel lining structure of the lower step of the left guide tunnel and excavate and expand it according to the new tunnel outline; (2) Construct the initial support (install steel arch frame, hang steel mesh, spray concrete and install anchor rod) and temporary support (install temporary vertical support N3, hang steel mesh and spray concrete) of the lower step of the left guide tunnel; (3) The upper and lower guide tunnels on the left side are staggered by no more than 5m.

[0076] Step 4: (1) Remove the original tunnel lining structure of the upper step of the middle pilot tunnel and expand the excavation according to the new tunnel outline; (2) Construct the initial support (install steel arch frame, hang steel mesh, spray concrete and install anchor rods) and temporary support (install temporary horizontal bracing N8, vertical bracing N4, hang steel mesh and spray concrete) of the upper step of the middle pilot tunnel; (3) The distance between the upper middle pilot tunnel and the upper left pilot tunnel shall not be greater than 15m.

[0077] Step 5: (1) Remove the original tunnel lining structure of the upper step of the right guide tunnel and expand the excavation according to the new tunnel outline; (2) Construct the initial support (install steel arch frame, hang steel mesh, spray concrete and install anchor rod) and temporary support (install temporary cross brace N9, hang steel mesh and spray concrete) of the upper step of the right guide tunnel; (3) The misalignment between the upper right guide tunnel and the upper left guide tunnel shall not exceed 15m.

[0078] Step 6: (1) Remove the original tunnel lining structure of the lower step of the middle pilot tunnel and expand the excavation according to the new tunnel outline; (2) Construct the initial support (install steel arch frame, hang steel mesh, spray concrete and install anchor rods) and temporary support (install temporary vertical bracing N6, hang steel mesh and spray concrete) of the lower step of the middle pilot tunnel; (3) The distance between the lower middle pilot tunnel and the upper middle pilot tunnel shall not be greater than 5m.

[0079] Step 7: (1) Remove the original tunnel lining structure of the lower step of the right guide tunnel and expand the excavation according to the new tunnel outline; (2) Construct the initial support of the lower step of the right guide tunnel (install steel arch frame, hang steel mesh, spray concrete and install anchor rods); (3) The distance between the lower right guide tunnel and the upper right guide tunnel shall not be greater than 5m.

[0080] Step 8: (1) Remove the vertical temporary support, pour the secondary lining of the inverted arch and backfill the inverted arch; (2) Lay the waterproof board and use the formwork trolley to pour the secondary lining concrete of the arch wall.

[0081] Furthermore, the specific steps for the widening excavation of the type IV lining section in step 4 are as follows:

[0082] Step 4.1.b: Construct tunnel pre-support, then construct the original tunnel secondary lining and add temporary support structure to the lower half of the tunnel section, and then backfill with sandbags to the tunnel arch position.

[0083] Step 4.2.b: In sequence, dismantle the original tunnel lining structure of the upper step of the left guide tunnel, the original tunnel lining structure of the lower step of the left guide tunnel, the original tunnel lining structure and secondary lining steel pipe support of the upper step of the right guide tunnel, the original tunnel lining structure and secondary lining temporary support of the middle step of the right guide tunnel, and the original tunnel lining structure of the lower step of the right guide tunnel. After each dismantling, excavate and widen the tunnel according to the new tunnel outline, and construct the corresponding initial support and temporary support structure. Then repeat the above steps to advance the tunnel.

[0084] Step 4.3.b: Remove temporary supports, pour the secondary lining of the invert arch and backfill the invert arch, lay waterproof membrane, and use a formwork trolley to pour the secondary lining concrete of the arch wall.

[0085] Step 4, the specific process for widening the excavation of the Type IV lining section, is as follows:

[0086] Step 1: (1) Construct tunnel advance support; (2) Construct the original tunnel secondary lining steel pipe support N5, secondary lining inclined support N4 and temporary vertical support N2 for the lower half section of the excavated tunnel; (3) Use sandbags to backfill to the tunnel arch waist position, requiring the backfill to be compacted.

[0087] Step 2: (1) Remove the original tunnel lining structure of the upper step of the left guide tunnel and excavate and expand it according to the new tunnel outline; (2) Construct the initial support (install steel arch frame, hang steel mesh, spray concrete and install anchor rod) and temporary support (install temporary support N1, hang steel mesh and spray concrete) of the upper step of the left guide tunnel; (3) Repeat the above steps to advance.

[0088] Step 3: (1) Remove the original tunnel lining structure of the lower step of the left guide tunnel and excavate and expand it according to the new tunnel outline; (2) Construct the initial support (install steel arch frame, hang steel mesh, spray concrete and install anchor rod) and temporary support (install temporary vertical support N3, hang steel mesh and spray concrete) of the lower step of the left guide tunnel; (3) The upper and lower guide tunnels on the left side are staggered by no more than 10m.

[0089] Step 4: (1) Remove the original tunnel lining structure and secondary lining steel pipe support N6 of the upper step of the right guide tunnel, and expand the excavation according to the new tunnel outline; (2) Construct the initial support of the upper step of the right guide tunnel (install steel arch frame, hang steel mesh, spray concrete and install anchor rods); (3) The distance between the upper right guide tunnel and the upper left guide tunnel shall not be greater than 20m.

[0090] Step 5: (1) Remove the original tunnel lining structure and the temporary secondary lining support N4 of the right guide tunnel middle step, and expand the excavation according to the new tunnel outline; (2) Construct the initial support of the right guide tunnel middle step (install steel arch frame, hang steel mesh, spray concrete and install anchor rods); (3) The right middle guide tunnel and the left upper guide tunnel are not more than 20m apart.

[0091] Step 6: (1) Remove the original tunnel lining structure of the lower step of the right guide tunnel and expand the excavation according to the new tunnel outline; (2) Construct the initial support of the lower step of the right guide tunnel (install steel arch frame, hang steel mesh, spray concrete and install anchor rods); (3) The misalignment between the upper right guide tunnel and the lower right guide tunnel shall not exceed 10m.

[0092] Step 7: (1) Remove temporary supports N1, N2 and N3, pour the secondary lining of the invert arch and backfill the invert arch; (2) Lay the waterproof board and pour the secondary lining concrete of the arch wall using a template trolley.

[0093] Furthermore, the specific steps for the widening excavation of the type IIIa lining section in step 4 are as follows:

[0094] Step 4.1.c: Remove the original tunnel lining structure of the upper bench, and widen the excavation according to the new tunnel outline, and construct the initial support for the upper bench;

[0095] Step 4.2.c: Remove the original tunnel lining structure on the left side of the lower step, expand the excavation according to the new tunnel outline, and construct the initial support;

[0096] Step 4.3.c: Remove the original tunnel lining structure on the right side of the lower step, expand the excavation according to the new tunnel outline, and construct the initial support.

[0097] Step 4, the specific process for widening the excavation of the type IIIa lining section, is as follows:

[0098] Step 1: (1) Remove the original tunnel lining structure of the upper step and expand the excavation according to the new tunnel outline; (2) Construct the initial support of the upper step (install anchor bolts, hang steel mesh and spray concrete); (3) Repeat the above steps to advance.

[0099] Step 2: (1) Remove the original tunnel lining structure on the left side of the lower step and expand the excavation according to the new tunnel outline; (2) Construct initial support (install anchor bolts, hang steel mesh and spray concrete); (3) The distance between the upper step and the lower left step shall not be greater than 30m.

[0100] Step 3: (1) Remove the original tunnel lining structure on the right side of the lower step and expand the excavation according to the new tunnel outline; (2) Construct initial support (install anchor bolts, hang steel mesh and spray concrete); (3) The distance between the upper step and the lower right step shall not exceed 30m.

[0101] Furthermore, the specific steps for the widening excavation of the type IIIb lining section in step 4 are as follows:

[0102] Step 4.1.d: Construct the secondary lining diagonal bracing of the original tunnel, and then backfill with stone ballast to form an operating platform;

[0103] Step 4.2.d: In sequence, dismantle the original tunnel lining structure of the upper step, the temporary diagonal bracing of the secondary lining on the left side of the middle step and the original tunnel lining structure, the temporary diagonal bracing of the secondary lining on the middle step and the original tunnel lining structure on the right side, the original tunnel lining structure on the left side of the lower step and the original tunnel lining structure on the right side of the lower step. After each dismantling, excavate and widen the tunnel according to the new tunnel outline, and construct the corresponding initial support and temporary support structures. Then repeat the above steps to advance the tunnel.

[0104] Step 4, the specific process for widening the excavation of the type IIIb lining section, is as follows:

[0105] Step 1: (1) Construct temporary inclined supports N1 and N2 for the secondary lining of the original tunnel; (2) Backfill with stone chips to form an operating platform.

[0106] Step 2: (1) Remove the original tunnel lining structure of the upper step and expand the excavation according to the new tunnel outline; (2) Construct the initial support of the upper step (install steel arch frame, hang steel mesh, spray concrete and install anchor rods); (3) Repeat the above steps to advance.

[0107] Step 3: (1) Remove the temporary diagonal bracing N1 on the left side of the middle step and the original tunnel lining structure, and expand the excavation according to the new tunnel outline; (2) Construct initial support (install steel arch frame, hang steel mesh, spray concrete and install anchor rods); (3) The misalignment between the upper step and the left middle step shall not exceed 30m.

[0108] Step 4: (1) Remove the temporary diagonal bracing N2 of the secondary lining of the middle step and the original tunnel lining structure on the right side, and expand the excavation according to the new tunnel outline; (2) Construct initial support (install steel arch frame, hang steel mesh, spray concrete and install anchor rods); (3) The misalignment between the upper step and the right middle step shall not exceed 30m.

[0109] Step 5: (1) Remove the original tunnel lining structure on the left side of the lower step and expand the excavation according to the new tunnel outline; (2) Construct initial support (install steel arch frame, hang steel mesh, spray concrete and install anchor rods); (3) The distance between the upper step and the lower left step shall not be greater than 30m.

[0110] Step 6: (1) Remove the original tunnel lining structure on the right side of the lower step and expand the excavation according to the new tunnel outline; (2) Construct initial support (install steel arch frame, hang steel mesh, spray concrete and install anchor rods); (3) The distance between the upper step and the lower right step shall not be greater than 30m.

[0111] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for tunnel lining removal and widening excavation, characterized in that, The specific steps include the following: Step 1: First, the tunnel lining structure is cut circumferentially along the tunnel centerline using a cutting process. Then, based on the circumferential cutting, longitudinal cutting is performed to form multiple block-shaped regional structures. Step 2: During the longitudinal cutting process, temporary support structures are added to the lining structure to support and reinforce it. Step 3: Simultaneously dismantle the block-shaped structures formed by circumferential and longitudinal cutting of the lining structure. Step 4: Expand the tunnel for different blocky area structures.

2. The tunnel lining removal and widening construction method according to claim 1, characterized in that, The specific content of step 1 is as follows: Step 1.1: Use a hydraulic cutting machine for secondary lining concrete to make circumferential cuts at intervals, thereby dividing a lining unit into multiple segments, and then make longitudinal cuts. Step 1.2: After circumferential and longitudinal cutting, different blocky regional structures will be formed, and the blocky regional structures are successively divided into Zone I, Zone II, Zone III, Zone IV and Zone V. Temporary support structures are added to support different blocky regions. Among them, the surrounding rock of different lining sections in Zones III, IV and V is further divided into Type a and Type b.

3. The tunnel lining removal and widening construction method according to claim 2, characterized in that, The specific content of step 1.2 is as follows: During the construction of Zone I, a hydraulic cutter for the secondary lining concrete was first used to cut the No. 1 joint, then the No. 2 joint, and finally the No. 3 joint. The No. 1 and No. 2 joints were staggered by a distance from the outer edge of the temporary support during construction.

4. The tunnel lining removal and widening construction method according to claim 3, characterized in that, Step 1.2 further includes the following: First, a hydraulic cutting machine for secondary lining concrete is used to cut the IVb and IVa lining sections circumferentially. Then, longitudinal sections are cut separately, and support structures are added to the IVa and IVb lining sections.

5. The tunnel lining removal and widening construction method according to claim 4, characterized in that, Step 1.2 further includes the following: During construction, a hydraulic cutting machine for secondary lining concrete is first used to cut the lining sections in a circumferential manner according to the type IIIa and type IIIb lining sections, and then the sections are cut longitudinally.

6. The tunnel lining demolition and widening construction method according to claim 5, characterized in that, The specific steps for the widening excavation of the type V lining section in step 4 are as follows: Step 4.1.a: After constructing the tunnel pre-support, the original tunnel secondary lining and the lower half of the tunnel section were enlarged and temporary support structures were added. Then, sandbags were used to backfill to the tunnel arch position. Step 4.2.a: In sequence, demolish the original tunnel lining structure of the upper step of the left pilot tunnel, the lower step of the left pilot tunnel, the upper step of the middle pilot tunnel, the upper step of the right pilot tunnel, the lower step of the middle pilot tunnel, and the lower step of the right pilot tunnel. After each demolition, excavate and widen the tunnel according to the new tunnel outline, and construct the corresponding initial support and temporary support structures. Step 4.3.a: Remove the vertical temporary supports, pour the secondary lining of the invert arch and backfill the invert arch, lay the waterproof membrane, and use a formwork trolley to pour the secondary lining concrete of the arch wall.

7. The tunnel lining demolition and widening construction method according to claim 5, characterized in that, The specific steps for the widening excavation of the type IV lining section in step 4 are as follows: Step 4.1.b: Construct tunnel pre-support, then construct the original tunnel secondary lining and add temporary support structure to the lower half of the tunnel section, and then backfill with sandbags to the tunnel arch position. Step 4.2.b: In sequence, dismantle the original tunnel lining structure of the upper step of the left guide tunnel, the original tunnel lining structure of the lower step of the left guide tunnel, the original tunnel lining structure and secondary lining steel pipe support of the upper step of the right guide tunnel, the original tunnel lining structure and secondary lining temporary support of the middle step of the right guide tunnel, and the original tunnel lining structure of the lower step of the right guide tunnel. After each dismantling, excavate and widen the tunnel according to the new tunnel outline, and construct the corresponding initial support and temporary support structure. Then repeat the above steps to advance the tunnel. Step 4.3.b: Remove temporary supports, pour the secondary lining of the invert arch and backfill the invert arch, lay waterproof membrane, and use a formwork trolley to pour the secondary lining concrete of the arch wall.

8. The tunnel lining removal and widening construction method according to claim 5, characterized in that, The specific steps for the widening excavation of the type IIIa lining section in step 4 are as follows: Step 4.1.c: Remove the original tunnel lining structure of the upper bench, and widen the excavation according to the new tunnel outline, and construct the initial support for the upper bench; Step 4.2.c: Remove the original tunnel lining structure on the left side of the lower step, expand the excavation according to the new tunnel outline, and construct the initial support; Step 4.3.c: Remove the original tunnel lining structure on the right side of the lower step, expand the excavation according to the new tunnel outline, and construct the initial support.

9. The tunnel lining demolition and widening construction method according to claim 5, characterized in that, The specific steps for the excavation of the type IIIb lining section in step 4 are as follows: Step 4.1.d: Construct the secondary lining diagonal bracing of the original tunnel, and then backfill with stone ballast to form an operating platform; Step 4.2.d: In sequence, dismantle the original tunnel lining structure of the upper step, the temporary diagonal bracing of the secondary lining on the left side of the middle step and the original tunnel lining structure, the temporary diagonal bracing of the secondary lining on the middle step and the original tunnel lining structure on the right side, the original tunnel lining structure on the left side of the lower step and the original tunnel lining structure on the right side of the lower step. After each dismantling, excavate and widen the tunnel according to the new tunnel outline, and construct the corresponding initial support and temporary support structures. Then repeat the above steps to advance the tunnel.

10. The tunnel lining demolition and widening construction method according to claim 1, characterized in that, The temporary support structure adopts two forms: I-beams and steel pipe columns. After the temporary support structure is added, the tunnel space is backfilled.

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