Underground space lateral underground excavation extension method and underground structure obtained by same
By constructing an integrated structural system that coordinates and links existing structure, temporary support, permanent support, and waterproofing system, the problems of construction safety and waterproofing connection in underground space expansion were solved, and the structural stability and waterproof sealing were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-05
- Publication Date
- 2026-04-14
AI Technical Summary
The expansion of existing underground spaces presents safety risks due to the difficulty in precisely controlling ground disturbance during construction, which could easily lead to collapse and ground subsidence. Furthermore, the connection between the old and new waterproofing systems is difficult to ensure a tight seal, resulting in significant leakage hazards.
A synergistic structural system is constructed, consisting of existing structure, temporary support, permanent support, and waterproofing system. Through steps such as temporary support, pipe roof grouting reinforcement, and overlapping of waterproofing layers, a continuous waterproof barrier is formed, enhancing structural stability and waterproof sealing.
Effectively control soil displacement, prevent collapse and leakage, ensure construction safety and project quality, and achieve stable expansion and functional upgrade of existing underground space.
Smart Images
Figure CN121854098A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of urban underground space, specifically relating to a method for lateral tunneling and expansion of underground space and the underground structure obtained by the method. Background Technology
[0002] Currently, due to limited technology and other factors, some existing underground spaces suffer from problems such as small scale and limited functionality, only covering local traffic nodes and failing to form a networked traffic management system, thus having little effect on alleviating overall traffic congestion. Against this backdrop, promoting the upgrading and expansion of existing underground spaces to achieve functional upgrades and scale expansion has become an urgent need for high-quality urban development. The cut-and-cover method, due to its significant advantages such as not requiring large-scale demolition of surface buildings and minimal interference with surface traffic and the surrounding environment, has become the preferred technology for underground space expansion. However, this technology faces two core challenges in its application: first, it is difficult to precisely control ground disturbance during construction, easily leading to safety risks such as collapse and ground subsidence, placing extremely high demands on the precision of construction techniques and risk control capabilities; second, there are technical pain points in the connection between new and old structures, as the original waterproofing system of the existing structure is easily damaged and fails during excavation, resulting in difficulty in achieving a tight waterproof connection, prominent leakage risks, and seriously affecting the quality and service life of the project.
[0003] Therefore, developing a waterproof layer overlapping technology that can adapt to the deformation characteristics of existing station external construction and expansion structures and has strong durability has become an urgent need to solve the current engineering pain points. Summary of the Invention
[0004] In order to solve the technical problems existing in the prior art, the present invention provides a method for lateral excavation and expansion of underground space and the underground structure obtained by the method, which constructs an overall structural system that coordinates and links "existing structure, temporary support, permanent support, waterproofing system and reinforcement measures".
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention proposes a method for lateral excavation and expansion of underground space, comprising the following steps: Step 1: Construct temporary support columns on one side of the existing station, and install temporary support longitudinal beams on the upper part of the temporary support columns to connect with the existing structural top slab; reserve holes in the longitudinal direction of the temporary support steel longitudinal beams; Step 2: Construct the pipe roof and connect it to the holes. After the pipe roof is installed, fill the soil pores using grouting. Strengthen the strata; Step 3: Demolish the existing side walls; Step 4: Carry out excavation work in Zone I; after excavating Zone I to the design elevation, carry out initial support construction; Step 5: After the initial support strength of Zone I meets the standard, excavation of Zone II will commence. After the excavation of Zone II is completed, the same standard initial support will be applied. Support; after the initial support is stable, clean the base layer until it is flat and dry, then lay the polymer waterproof membrane and carry out the secondary lining and pouring construction. Step 6: After the secondary lining construction is completed, the pipe roof and initial support in Zone I are precisely cut; after the cutting is completed, the layered back excavation construction is carried out in the corresponding area of the existing structure. Step 7: After the pipe roof and initial support are cut, carry out the waterproof layer overlap construction in the area above the existing structure where soil is excavated. Step 8: Construct permanent structural support columns and longitudinal beams in Zone I. The upper steel bars of the longitudinal beams are anchored directly to the existing structure, and the lower steel bars are anchored directly to the interior of the new structure to make it an integral structure. When the concrete strength reaches the set level, the temporary supports are removed.
[0006] As a further technical solution, in step 3: to reduce the disturbance to the surrounding soil and existing structure caused by the demolition of the sidewall, the soil outside the sidewall to be demolished is first pre-grouted and reinforced. Composite cement grout is used for layered, hole-by-hole grouting to ensure uniform reinforcement. After the grout reaches the design strength, the sidewall is demolished by mechanical cutting and manual chiseling. The settlement and displacement of the structure are monitored in real time, and the demolition speed and sequence are strictly controlled to ensure construction safety.
[0007] As a further technical solution, in step 4: after the existing sidewall is demolished, excavation work is carried out in Zone I. During the excavation process, the thickness and speed of each layer are strictly controlled to avoid over-excavation that could lead to soil instability. At the same time, excavated soil is promptly cleared to reduce the impact of load accumulation on the surrounding strata. After Zone I is excavated to the design elevation, initial support construction is immediately organized to prevent collapse accidents.
[0008] As a further technical solution, the initial support standard for Zone II is the same as that for Zone I.
[0009] As a further technical solution, when cutting the pipe roof and initial support in Zone I, ensure the flatness of the cut.
[0010] As a further technical solution, in step 7, the existing structural waterproof layer pre-reserved section is first thrown into the interior of the structure, and the new... The waterproof layer on the building side is extended to the new space simultaneously. Then, the waterproof layers on both sides are precisely connected on the working surface of Zone I to ensure that the overlap length meets the design requirements and the joints are tight and firm, forming a complete waterproof system and eliminating the risk of leakage.
[0011] As a further technical solution, the grouting reinforcement zone described in step 7 covers part of the existing structure and part of the newly constructed structure.
[0012] As a further technical solution, in step 8, when the concrete strength reaches a set level, the temporary support is then removed.
[0013] As a further technical solution, the excavation depth of Zone II is greater than that of Zone I.
[0014] Secondly, the present invention proposes an underground structure that is expanded using the aforementioned method of lateral tunneling and expansion of underground space.
[0015] This invention addresses the lateral excavation and expansion of existing stations by constructing a synergistic structural system integrating "existing structure - temporary support - permanent support - waterproofing." Each component is clearly defined, functionally complementary, and the construction process is seamlessly connected. Specifically: From a structural composition and function perspective, the core foundation is the existing structure, including both the existing structure itself and its waterproofing layer. The former provides a stable load-bearing foundation for the expansion project, while the latter ensures the original waterproofing performance of the existing space. The main structure of the newly constructed expansion space is located on one side of the existing structure and serves as the core functional carrier for achieving spatial expansion. The two are connected through multiple systems to form a complete structure. The temporary support system consists of temporary support columns and temporary support beams. The temporary support columns are vertically installed at designated locations on the expansion side of the existing station, while the temporary support beams are horizontally erected above the support columns and tightly connected to the top slab of the existing structure. Rectangular holes spaced 60cm apart are reserved on the beams to bear the vertical and horizontal loads in the early stages of construction and to provide operational access for subsequent pipe roof construction.
[0016] As an advanced support component, the pipe roof is constructed with pre-reserved holes in the corresponding longitudinal beams at 60cm intervals, penetrating deep into the soil. After grouting reinforcement, it can effectively restrain soil displacement and prevent collapse during excavation. The permanent support system consists of an initial support structure and a secondary lining structure. The initial support structure is constructed immediately at the bottom of the pipe roof after excavation using the pile method. It can prevent the upper soil or surrounding rock from squeezing into the construction space, creating a safe environment for subsequent operations. The secondary lining structure is poured along its inner side after the initial support has passed acceptance, serving as a permanent protective layer for the extended structure. The waterproofing system includes the existing structure's waterproofing layer, the new structure's waterproofing layer, and the waterproofing overlap layer. The waterproofing layers are laid between the initial support and the secondary lining, with extension sections reserved during construction. Later, the new and old waterproofing layers are connected through the waterproofing overlap layer, forming a seamless waterproof barrier and eliminating the risk of leakage. The support system includes a grouting reinforcement zone and concrete support columns. The grouting reinforcement zone is applied to the soil of the side wall to be demolished and the waterproofing overlap area, which can enhance soil stability, fill gaps at the waterproofing interface, and strengthen the overall structure and waterproofing seal. The concrete support columns are constructed before the temporary supports are removed, replacing the temporary components to bear the vertical load and ensuring the long-term operational structural stability.
[0017] The beneficial effects of this invention are as follows: This invention aims to solve two core technical challenges in the lateral excavation and expansion of existing underground spaces, while simultaneously addressing a series of derivative issues related to structural stability and waterproofing. Firstly, during the expansion of existing underground spaces, the excavation process easily disturbs the surrounding strata, making it difficult to precisely control soil displacement and potentially leading to safety risks such as collapse and ground subsidence. Therefore, temporary supports are first installed for reinforcement to ensure the stability of the existing structure during subsequent construction. These temporary supports include temporary support columns and longitudinal beams. After curing, pipe roofs are constructed, with pre-reserved holes in the longitudinal beams to facilitate the next step of pipe roof construction. After the pipe roofs are completed, grouting reinforcement is performed to form advanced support. Subsequently, the existing sidewall soil on one side of the excavation is reinforced before the sidewall is demolished to create space for the excavation operation. After excavating Zone I, an initial support structure is constructed to prevent soil collapse. Then, Zone II is excavated, and initial support, a new waterproof layer, and a secondary lining structure are constructed sequentially, completing the zoned support and waterproof foundation construction. Trial implementation of the initial support and secondary lining structures effectively increases the stability of the new structure. The purpose of cutting the pipe roof and initial support in Zone I is to provide working space for the overlapping of the waterproof layer. Then, soil is excavated from the existing structure to continue creating conditions for the overlapping of the waterproof layer. The new and old waterproof layers are connected through the waterproof overlap layer to form a continuous waterproof system. Finally, the permanent structure is constructed, and concrete support columns and longitudinal beams are poured. The longitudinal beam reinforcement is bent and anchored into both the existing and new structures, making the overall structure a unified load-bearing unit, thus completing the expansion project. This constructs a synergistic structural system integrating the existing structure, temporary support, permanent support, waterproof system, and reinforcement measures. Attached Figure Description
[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.
[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a cross-sectional view of the temporary support for the installation of this invention; Figure 3 This is a schematic diagram of the pre-reserved pipe roof construction hole in the longitudinal beam of the present invention; Figure 4 This is a schematic diagram of the initial support and secondary lining during forward excavation construction according to the present invention; Figure 5 This is a schematic diagram of the initial support cutting for the pipe roof of the present invention. Figure 6 This is a detailed drawing of the overlapping of the waterproof layer in this invention; Figure 7 This is a schematic diagram of the permanent structure construction of the present invention; The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.
[0020] 1. Soil; 2. Existing structure; 3. Existing station waterproofing layer; 4. Backfill area; 5. Grouting reinforcement area; 6. Concrete longitudinal beam; 7. Waterproofing overlap layer; 8. Concrete support column; 9. Pipe shed; 10. New structure waterproofing layer; 11. New initial support; 12. Secondary lining structure; 13. Temporary support longitudinal beam; 14. Temporary support column; 15. Rectangular opening; 16. Reinforcing steel connecting to the existing structure; 17. Reinforcing steel connecting to the new structure; Detailed Implementation It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0021] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. For ease of description, the words "up," "down," "left," and "right" appearing in this invention only indicate that they are consistent with the up, down, left, and right directions of the accompanying drawings themselves, and do not limit the structure. They are merely for the purpose of facilitating the description of this invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0022] As described in the background section, existing technologies have shortcomings. To address these technical problems, this invention proposes a method for lateral excavation and expansion of underground spaces. This invention aims to solve two core technical challenges in existing lateral excavation and expansion projects of underground spaces, while also overcoming a series of derivative issues related to structural stability and waterproofing. First, during the expansion of existing underground spaces, excavation easily disturbs the surrounding strata, making it difficult to accurately control soil displacement and potentially leading to safety risks such as collapse and ground subsidence. Therefore, temporary supports are first installed for reinforcement to ensure the stability of the existing structure remains unchanged during subsequent construction. The temporary supports include temporary support columns and longitudinal beams. After curing, pipe roofs are constructed, with pre-reserved holes in the corresponding longitudinal beams to facilitate the next step of pipe roof construction. After the pipe roofs are constructed, grouting reinforcement is performed to form advanced support. Subsequently, the existing sidewall soil on one side is reinforced before the sidewall is broken up to create space for the excavation operation. After excavating Zone I, the initial support structure is constructed to prevent soil collapse. Then, Zone II is excavated, and the initial support, the new waterproofing layer, and the secondary lining structure are constructed sequentially, completing the zoned support and waterproofing foundation construction. Trial construction of the initial support and secondary lining structure effectively increases the stability of the new structure. The purpose of cutting the pipe roof and initial support in Zone I is to provide working space for the waterproofing layer overlap. Then, soil is excavated from the existing structure to continue creating conditions for the waterproofing layer overlap. The new and old waterproofing layers are connected through the waterproofing overlap layer to form a continuous waterproofing system. Finally, the permanent structure is constructed, with concrete support columns and longitudinal beams poured. The longitudinal beam reinforcement is bent and anchored into both the existing and new structures, making the overall structure a unified load-bearing unit, ultimately completing the expansion project. This constructs a synergistic structural system integrating the existing structure, temporary support, permanent support, waterproofing system, and reinforcement measures.
[0023] In a typical embodiment of the present invention, such as Figure 1 As shown in the figure, this embodiment provides a method for lateral tunneling and expansion of underground space.
[0024] This invention addresses the lateral tunneling expansion project of an existing station by constructing a synergistic structural system integrating "existing structure - temporary support - permanent support - waterproofing." Each component is clearly defined, functionally complementary, and the construction process is seamlessly connected. Specifically, from a structural composition and function perspective, the core foundation is the existing structure 2, which includes the existing structure and its waterproofing layer 3. The former provides a stable load-bearing foundation for the expansion project, while the latter ensures the original waterproofing performance of the existing space. The main structure 10 of the newly constructed expansion space is located on one side of the existing structure and serves as the core functional carrier for achieving space expansion. The two are connected through multiple systems to form a complete structure.
[0025] like Figure 2 , Figure 3As shown, the temporary support system consists of temporary support columns 14 and temporary support longitudinal beams 13. The temporary support columns 14 are constructed vertically at designated locations on the side of the existing station expansion. The temporary support longitudinal beams 13 are horizontally erected above the support columns and tightly connected to the top slab of the existing structure. Rectangular holes 15 with a spacing of 60cm are reserved on the longitudinal beams, which not only bear the vertical and horizontal loads in the early stage of construction but also provide an operating passage for subsequent pipe roof construction. The pipe roof 9, as an advanced support component, is constructed at a spacing of 60cm corresponding to the reserved holes in the longitudinal beams and penetrates deep into the soil. After grouting reinforcement, it can effectively restrain soil displacement and prevent collapse during excavation.
[0026] Furthermore, the permanent support system consists of an initial support structure 11 and a secondary lining structure 12. The initial support structure 11 is constructed immediately at the bottom of the pipe roof after the excavation using the pile method. It can prevent the upper soil or surrounding rock from squeezing into the construction space, creating a safe environment for subsequent operations. The secondary lining structure 12 is poured along its inner side after the initial support has passed acceptance, serving as the permanent protective layer for the extended structure.
[0027] The waterproofing system includes an existing structural waterproofing layer 3, a newly constructed structural waterproofing layer 10, and a waterproofing overlap layer 7. All waterproofing layers are laid between the initial support structure and the secondary lining structure, and extension sections are reserved during construction. The new and old waterproofing layers are connected through the waterproofing overlap layer 7 to form a seamless waterproofing barrier and eliminate the risk of leakage.
[0028] The support system includes a grouting reinforcement zone 5 and concrete support columns 8. The grouting reinforcement zone 5 is constructed for the soil of the side wall to be demolished and the waterproof overlap area, which can enhance soil stability, fill the gaps at the waterproof interface, and strengthen the overall structure and waterproof sealing. The concrete support columns 8 are constructed before the temporary supports are removed, replacing the temporary components to bear the vertical load and ensuring the long-term operational structural stability.
[0029] The specific construction methods are as follows: Step 1. Install temporary supports like Figure 2 , Figure 3 As shown, temporary support columns 14 are constructed on one side of the existing station. Temporary support longitudinal beams 13 are then constructed on top of the temporary support columns 14, connecting to the existing structural roof slab. Rectangular holes 15 are pre-drilled in the longitudinal direction of the temporary support steel longitudinal beams 13, with a spacing of 60cm between adjacent rectangular holes 15. These pre-drilled rectangular holes 15 facilitate the construction of the pipe roof in the next stage. The pre-drilled holes in the support steel longitudinal beams 13 facilitate the construction of the pipe roof.
[0030] Step 2. Construct the pipe shed To ensure the stability of the existing structure and the restraint effect of the surrounding soil, a pipe roof support system is precisely constructed on the side of the existing structure to be constructed. Each pipe roof (9) must correspond one-to-one with the pre-reserved rectangular holes in the temporary support longitudinal beams, with hole position deviations conforming to specifications. The clear distance between pipe roofs is set at 60mm as designed to ensure continuous and complete support. After the pipe roof (9) is installed, cement grout is injected using a high-pressure grouting process. The grouting pressure and dosage are strictly controlled. The grout fills the soil pores, reinforcing the stratum and improving the soil's bearing capacity and deformation resistance, thus laying a solid safety foundation for subsequent excavation operations. (See [reference needed]). Figure 4 ; Step 3. Demolition of existing side walls To minimize disturbance to the surrounding soil and existing structure caused by the demolition of the sidewall, the soil outside the sidewall was first pre-grouted for reinforcement. Composite cement grout was used for layered, hole-by-hole grouting to ensure uniform reinforcement. After the grout reached its design strength, the sidewall was demolished using a combination of mechanical cutting and manual chiseling. Structural settlement and displacement were monitored in real time, and the demolition speed and sequence were strictly controlled to ensure construction safety. (See also...) Figure 4 ; Step 4. Excavate Zone I and construct initial support. To minimize disturbance to the surrounding soil and existing structure caused by the demolition of the sidewall, the soil outside the sidewall to be demolished was first pre-grouted for reinforcement. Composite cement grout was used for layered, hole-by-hole grouting to ensure uniform reinforcement. After the grout reached its design strength, the sidewall was demolished using a combination of mechanical cutting and manual chiseling, i.e., excavation of Zone I was carried out. During the excavation process, the structural settlement and displacement were monitored in real time, and the demolition speed and sequence were strictly controlled to ensure construction safety. (See also...) Figure 4 In this embodiment, Zone I is the area adjacent to the existing structure, and the excavation depth of this area is much smaller than that of Zone II below. Step 5. Excavate Zone II and construct initial support, waterproofing layer, and secondary lining. After the initial support strength of Zone I meets the standard, excavation of Zone II will proceed using the same process. Upon completion, initial support of the same standard will be installed immediately (see [link to relevant documentation]). Figure 7 The initial support in the newly constructed structure (11) ensures the continuity and coordinated stress distribution of the support. After the support is stable, the base layer is cleaned until it is flat and dry before laying the polymer waterproof membrane (see [reference]). Figure 6 , Figure 7 (7) New structural waterproofing layer, ensuring tight joints and additional layers at internal and external corners; after the waterproofing layer passes inspection, organize the secondary lining pouring construction, see [link to relevant documentation]. Figure 7 The secondary lining structure 12 in the middle; Step 6. Initial support cutting for the pipe roof, and backfilling of the existing structure. After the secondary lining is completed, precise cutting operations are performed on the pipe roof and initial support in Zone I. During the cutting process, the flatness of the cut is strictly controlled to avoid disturbing the surrounding existing structure. After the cutting is completed, layered backfilling is carried out in the corresponding area of the existing structure to create flat and compliant construction conditions for the seamless overlap of the subsequent waterproofing layer; see [link to relevant documentation] for the area to be covered by backfilling. Figure 6 , Figure 7 4. Anti-soil excavation zone in the middle; Step 7. Waterproof layer overlap After the pipe roof and initial support are cut, waterproofing layer overlap construction is carried out in the area above the existing structure where soil has been excavated. First, the pre-reserved section of the waterproofing layer on the existing structure side is inserted into the structure, and simultaneously, an extension section of the waterproofing layer on the new structure side is reserved to extend into the new space. Then, the waterproofing layers on both sides are precisely aligned at the work surface in Zone I, ensuring that the overlap length meets design requirements and the joints are tight and secure, forming a complete waterproofing system. Grouting is then injected into the waterproofing overlap area to fill the interface gaps, simultaneously strengthening the waterproofing seal and the structural integrity of the overlap area, eliminating potential leakage risks. It should be noted that the grouting reinforcement area covers part of the existing structure and part of the new structure.
[0031] Step 8. Construction of permanent structures like Figure 7 As shown, permanent structural support columns and longitudinal beams are constructed in Zone I. See details... Figure 7 The concrete support column 8 and concrete longitudinal beam 6 are permanent structural support columns and beams; the upper reinforcement of the longitudinal beam (corresponding to...) Figure 7 The middle reinforcement bar (16) connecting to the existing structure is anchored directly to the existing structure, and the lower reinforcement bar (17) connecting to the new structure is anchored directly into the new structure to make it a whole structure. When the concrete strength reaches a certain level, the temporary supports are removed.
[0032] In the above construction method, the waterproof layer is left with an extension section. After the secondary lining, part of the pipe roof and the initial support are cut off to increase the excavation overlap space, so as to achieve precise overlap. Then, the overlap part is reinforced by grouting to adapt to dynamic displacement, form a continuous waterproof barrier, and solve the leakage risk.
[0033] The above construction method involves layered, targeted reinforcement design: the first step is to grout the waterproof overlap areas to fill interface gaps, simultaneously strengthening the waterproof sealing and the structural integrity of the overlap areas; the second step is to remove the temporary support columns and beams, and then construct permanent concrete columns and beams on the existing station side to bear the vertical load. Layered reinforcement addresses both the weak points in waterproofing and the structural load-bearing issues, ensuring construction and operational stability.
[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for lateral excavation and expansion of underground space, characterized in that, Includes the following steps: Step 1: Construct temporary support columns on one side of the existing station, and install temporary support longitudinal beams on the upper part of the temporary support columns to connect with the existing structural top slab; reserve holes in the longitudinal direction of the temporary support steel longitudinal beams; Step 2: Construct the pipe roof and connect it to the holes. After the pipe roof is installed, fill the soil pores using grouting. Strengthen the strata; Step 3: Demolish the existing side walls; Step 4: Carry out excavation work in Zone I; after excavating Zone I to the design elevation, carry out initial support construction; Step 5: After the initial support strength of Zone I meets the standard, excavation of Zone II will commence. After the excavation of Zone II is completed, the same standard initial support will be applied. Support; after the initial support is stable, clean the base layer until it is flat and dry, then lay the polymer waterproof membrane and carry out the secondary lining and pouring construction. Step 6: After the secondary lining construction is completed, the pipe roof and initial support in Zone I are precisely cut; after the cutting is completed, the layered back excavation construction is carried out in the corresponding area of the existing structure. Step 7: After the pipe roof and initial support are cut, waterproof layer overlap construction and grouting are carried out in the area above the existing structure where soil is excavated. Step 8: Construct permanent structural support columns and longitudinal beams in Zone I, with the upper steel bars of the longitudinal beams anchored directly to the existing structure and the lower steel bars anchored directly to the interior of the new structure to make it an integral structure.
2. The method for lateral tunneling and expansion of underground space as described in claim 1, characterized in that, In step 3, the soil outside the demolished sidewall is first pre-grouted and reinforced. Composite cement grout is used for layered and hole-by-hole grouting to ensure uniform reinforcement. After the grout reaches the design strength, the sidewall is demolished by mechanical cutting and manual chiseling. The settlement and displacement of the structure are monitored in real time, and the demolition speed and sequence are strictly controlled.
3. The method for lateral excavation and expansion of underground space as described in claim 1, characterized in that, In step 4: after the existing sidewall is demolished, the soil excavation operation of Zone I is carried out; during the excavation process, the thickness of each layer and the speed of advancement are strictly controlled, and the excavated soil is cleared in a timely manner; after Zone I is excavated to the design elevation, the initial support construction is immediately organized to prevent the collapse accident.
4. The method for lateral tunneling and expansion of underground space as described in claim 1, characterized in that, Initial support standards for Zone II The initial support standards are the same as those for Zone I.
5. The method for lateral tunneling and expansion of underground space as described in claim 1, characterized in that, In the initial stage of the pipe shed in Zone I When cutting the support, ensure the cut is smooth.
6. The method for lateral tunneling and expansion of underground space as described in claim 1, characterized in that, In step 7, the existing The pre-reserved section of the structural side waterproofing layer is thrown into the interior of the structure, and the newly built structural side waterproofing layer is simultaneously reserved with an extension section to the newly built space. Then, the waterproofing layers on both sides are precisely connected on the working surface of Zone I to ensure that the overlap length meets the design requirements and the joint is tight and firm, forming a complete waterproofing system.
7. The method for lateral excavation and expansion of underground space as described in claim 1, characterized in that, The grouting reinforcement zone described in step 7 covers part of the existing structure and part of the newly constructed structure.
8. The method for lateral tunneling and expansion of underground space as described in claim 1, characterized in that, In step 8, when the concrete strength reaches the set level, the temporary supports are then removed.
9. The method for lateral excavation and expansion of underground space as described in claim 1, characterized in that, The excavation depth of Zone II is greater than that of Zone I.
10. An underground structure, characterized in that, It utilizes the lateral tunneling method described in any one of claims 1-9 to expand underground space. The construction method is used for expansion.