Tunnel undercrossing shallow buried section deformation control device and method

Abstract

The invention discloses a deformation control device and method for a tunnel undercrossing shallow buried section, and relates to the technical field of tunnel construction.The deformation control device comprises a tunnel and further comprises an advance support structure, the advance support structure is arranged in a rock-soil body on the periphery of the arch portion and the side wall of the tunnel, and a water interception and seepage prevention structure is arranged between the advance support structure and the tunnel; the guiding pressure-bearing structure is arranged on the radial inner side of the water interception and seepage prevention structure and surrounds the upper half section of the tunnel, the self-control structure is arranged on the guiding pressure-bearing structure, the guiding pressure-bearing structure comprises two fixing piles, the two fixing piles are symmetrically arranged in stable stratums on the two sides of the design center line of the tunnel, and the two ends of the pressure-bearing ring are fixedly connected with the two fixing piles correspondingly; through cooperation of multiple structures, advanced reinforcement of surrounding rock, effective blocking of underground water, guiding and positioning of the tunnel and dynamic regulation and control of deformation are achieved, and therefore the problems that in the traditional technology, the deformation control effect is poor, the construction efficiency is low, and safety is insufficient are solved, and smooth construction of the tunnel penetrating through the shallow buried section downwards is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, specifically to a deformation control device and method for tunnels passing under shallow buried sections. Background Technology

[0002] In tunnel construction, shallow-buried sections are high-risk areas due to their thin overburden, high degree of weathering of surrounding rock, loose soil particles, and frequent groundwater seepage. Current technologies for tunneling under shallow-buried sections often employ simple grouting reinforcement or basic support structures for deformation control. Traditional grouting methods rely heavily on the experience of construction workers to set parameters, leading to uneven reinforcement effects and limited improvement in the self-stabilizing capacity of the surrounding rock in some areas. This results in issues such as arch extrusion and rockfall after excavation, failing to address the root cause of surrounding rock deformation. Furthermore, for shallow-buried sections rich in groundwater, current technologies often neglect the importance of water interception and seepage prevention, or rely on only single seepage prevention measures, which are insufficient to effectively block groundwater seepage. This results in the soil remaining in a saturated and softened state for extended periods, further reducing the strength of the surrounding rock and exacerbating tunnel deformation. Summary of the Invention

[0003] The purpose of this invention is to provide a deformation control device and method for tunnels passing under shallow buried sections. Through the coordinated operation of multiple structures, it can achieve advanced reinforcement of surrounding rock, effective isolation of groundwater, tunnel guidance and positioning, and dynamic regulation of deformation, thereby solving the problems of poor deformation control, low construction efficiency, and insufficient safety in traditional technologies, and ensuring the smooth progress of tunnel construction under shallow buried sections.

[0004] The above-mentioned optimized structure of the present invention is achieved through the following technical solution: a deformation control device for a tunnel passing under a shallow buried section, including a tunnel and an advanced support structure, wherein the advanced support structure is provided in the rock and soil mass surrounding the tunnel arch and sidewalls to pre-reinforce the surrounding rock and enhance the self-stabilizing ability of the surrounding rock. A water-cutting and seepage-prevention structure is provided between the advanced support structure and the tunnel to block groundwater seepage and prevent soil saturation and softening. A guiding pressure-bearing structure is located radially inside the water-cutting and seepage-proof structure and surrounds the upper half of the tunnel section to guide and position the outline of the tunnel, while bearing the surrounding rock pressure and limiting the deformation of the tunnel. A self-control structure is provided on the guide bearing structure to achieve adaptive control of deformation; The guiding pressure-bearing structure includes two fixed piles, which are symmetrically arranged in stable strata on both sides of the tunnel design centerline; The pressure-bearing ring is an arched structure. Both ends of the pressure-bearing ring are fixedly connected to the two fixed piles respectively. The top of the arch abuts against the water-cutting and seepage-proof structure. The interior of the arch is the excavation space of the tunnel, which is used to distribute and transfer the upper load to the fixed piles.

[0005] In some embodiments, the advanced support structure includes multiple outer reinforcing rods, which are symmetrically arranged on both sides of the tunnel. Multiple inner reinforcing rods are provided between multiple outer reinforcing rods, and the multiple outer reinforcing rods and multiple inner reinforcing rods are connected to the surrounding rock outside the tunnel.

[0006] In some embodiments, the water-cutting and seepage-prevention structure includes a water-cutting curtain, which is disposed between the advanced support structure and the tunnel to form a continuous water-stopping body; An impermeable layer is laid in close contact with the surface of the tunnel excavation outline. A drainage component is provided on the outside of the impermeable layer and is connected to the surface drainage system.

[0007] In some embodiments, the cutoff wall is formed by high-pressure jet grouting piles or cement-soil mixing piles; the seepage prevention layer is made of HDPE geomembrane composite waterproof board; the drainage component includes perforated corrugated pipes arranged circumferentially and longitudinally, which are wrapped with geotextile.

[0008] In some embodiments, the self-control structure includes a drive element disposed on the ground; A prestressed anchor cable, one end of which is connected to the output end of the drive component, and the other end is fixedly connected to the top of the pressure ring; A protective sleeve is embedded in the water-cutting and seepage-proof structure and is provided with the prestressed anchor cable through it; Multiple settlement monitoring points are set at equal intervals along the top contour of the pressure ring and are all electrically connected to the drive component to monitor the settlement of the surrounding rock and the deformation of the pressure ring in real time.

[0009] In some embodiments, the pressure-bearing ring includes multiple arc-shaped plates, which are connected end to end to form a semi-circular structure; A first insert plate is disposed on one side of the arc-shaped plate; The first slot is located at the bottom of the first insert plate; The second insert plate is located on the other side of the arc-shaped plate and is inserted into the first slot. The second slot is located on the top of the second insert plate and is inserted into and engaged with the first insert plate.

[0010] A method for controlling deformation of a tunnel passing under a shallow buried section includes the following steps: S1. Construction Preparation: Clear surface debris from the tunnel construction area, level the construction site, set up construction equipment and monitoring instruments, determine the tunnel mileage, elevation and grouting hole location, and complete the construction layout. S2. Advanced support construction: Along the outer edge of the tunnel excavation outline, the aforementioned advanced support structure is constructed to pre-reinforce the loose surrounding rock in the shallow buried section; S3. Construction of water-cutting and seepage-prevention structure: Above the tunnel arch, a water-cutting curtain is constructed inside the advanced support structure, and an anti-seepage layer and drainage components are laid on the excavation outline. S4. Construction of the guiding pressure-bearing structure: Fixed piles are constructed on both sides of the centerline of the tunnel, and then pressure-bearing rings are installed between the fixed piles to form a stable arched support system; S5. Installation and commissioning of the self-control structure: The self-control structure is installed on the pressure ring and then debugged. S6. Tunnel Excavation and Support: Under the protection of the pressure ring, the tunnel body is excavated, and the initial support and secondary lining of the tunnel are carried out simultaneously.

[0011] In some embodiments, in step S3, after installing the pressure ring, the adaptive control structure is installed simultaneously, the prestressed anchor cable is connected between the drive component and the pressure ring, and multiple settlement monitoring points are set up.

[0012] In some embodiments, during the entire tunnel construction and operation, deformation and stress data of the bearing ring are collected in real time through multiple settlement monitoring points; when the data exceeds the warning value, the drive components are automatically or manually controlled to dynamically compensate the support state of the bearing ring by adjusting the tension of the prestressed anchor cables, so as to control the deformation of the tunnel structure.

[0013] In some embodiments, in step S2, the drill holes corresponding to the outer and inner reinforcing rods are arranged in a 1.5m×1.5m quincunx pattern, and the corresponding grout is injected into them respectively. The grouting sequence is to inject the outer side first, and then push the grouting inward in sequence. The inner reinforcing rod is grouted with a 0.8:1 to 1:1 cement single-liquid grout; the outer reinforcing rod is grouted with a cement-water glass double-liquid grout, with water glass having a glass strength of 35-40 glass and a modulus of 2.4.

[0014] The above-described technical solutions in the embodiments of the present invention have at least the following technical effects or advantages: (1) The present invention pre-reinforces the surrounding rock by means of staggered reinforcing rods, thereby improving the self-stabilizing ability of the surrounding rock; the water interception and seepage prevention structure blocks the groundwater seepage through multiple defenses to prevent the soil from becoming saturated and softened; the guiding structure realizes the guiding positioning of tunnel construction and disperses the pressure of the surrounding rock; the self-control structure realizes real-time monitoring and dynamic control of deformation, actively restricts the development of deformation, and the four-fold protection ensures that the deformation is controlled within the design allowable range, effectively avoiding problems such as arch extrusion, rockfall, and excessive surface settlement, improving the deformation control and construction safety of the tunnel during the excavation process, thereby solving the problem of poor deformation control effect of single structure in traditional technology, and ensuring the stability of the surrounding rock and tunnel structure.

[0015] (2) The pressure ring of the present invention adopts a modular structure, which can be quickly assembled and disassembled by the insertion of the insert plate and the slot, making it convenient for construction and installation; the self-control structure can realize automated regulation, reduce manual intervention, reduce the labor intensity of construction personnel, and improve the timeliness and accuracy of deformation regulation. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a cross-sectional schematic diagram of the present invention inside a tunnel; Figure 2 This is an exploded view of the two arc-shaped plates of the present invention; Figure 3 This is a schematic diagram of the arc-shaped plate of the present invention; Figure 4 This is a flowchart of the deformation control method for tunnels passing under shallow buried sections according to the present invention.

[0018] In the diagram: 1. Tunnel; 2. Advanced support structure; 21. Outer reinforcing rod; 22. Inner reinforcing rod; 3. Water interception and seepage prevention structure; 31. Water interception curtain; 32. Seepage prevention layer; 33. Drainage component; 4. Guide pressure bearing structure; 41. Fixed pile; 42. Pressure bearing ring; 421. Arc plate; 422. First insert plate; 423. First slot; 424. Second insert plate; 425. Second slot; 5. Self-control structure; 51. Driving component; 52. Prestressed anchor cable; 53. Protective sleeve. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element 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.

[0021] Furthermore, 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] refer to Figure 1-3A deformation control device for a tunnel passing under a shallow buried section includes a tunnel 1, an advanced support structure 2, a water-cutting and seepage-prevention structure 3, a guiding pressure-bearing structure 4, and a self-control structure 5. These structures cooperate to form a complete deformation control system. The tunnel 1 is an underground tunnel structure to be excavated or already excavated, with a cross-sectional shape that is circular, horseshoe-shaped, or rectangular, depending on the actual engineering requirements. The tunnel 1 may include initial support and secondary lining. The initial support is laid out close to the excavation outline of the tunnel 1, using a combination of shotcrete, steel arches, and anchor bolts to withstand the surrounding rock pressure during the initial excavation of the tunnel 1 and limit surrounding rock deformation. The secondary lining is located inside the initial support and is constructed using cast-in-place concrete. It is used to withstand long-term surrounding rock pressure and overlying loads, improving the durability and stability of the tunnel structure. A waterproof layer is provided between the initial support and the secondary lining to further enhance the seepage prevention performance inside the tunnel and prevent groundwater from seeping into the tunnel 1. The advanced support structure 2 is located in the rock and soil surrounding the arch and sidewalls of tunnel 1. It can pre-reinforce the surrounding rock of tunnel 1, improve its self-stabilizing capacity, and provide safety assurance for tunnel excavation. The water interception and seepage prevention structure 3 is located between the advanced support structure 2 and tunnel 1, arranged around the excavation outline of tunnel 1, forming an integrated system of water interception, seepage prevention, and drainage. It is used to block groundwater seepage, prevent soil saturation and softening, protect the advanced support structure 2 and the tunnel 1 support structure, and improve structural durability. The guiding pressure bearing structure 4 is located radially inside the water interception and seepage prevention structure 3 and surrounds the upper half of the tunnel 1 section. It is located between the seepage prevention layer 32 and the initial tunnel support. It is used to guide and position the outline of tunnel 1, prevent over-excavation and under-excavation during tunnel excavation, bear the surrounding rock pressure, limit the deformation of tunnel 1, and evenly distribute the overlying load and surrounding rock pressure to the stable strata, avoiding local stress concentration in the support structure. During tunnel excavation, the deformation of the surrounding rock is a dynamic process. Traditional passive support structures cannot adjust the stress in real time according to the deformation. To further improve the timeliness and effectiveness of deformation control, this device also includes a self-control structure 5. The self-control structure 5 is set on the guide pressure-bearing structure 4 and works in conjunction with the guide pressure-bearing structure 4 and the water interception and seepage prevention structure 3. It is used to monitor the settlement of the surrounding rock and the deformation of the pressure ring 42 in real time, and dynamically adjust the support force of the pressure ring 42 according to the monitoring data, so as to realize the adaptive control of deformation and improve the accuracy and timeliness of deformation control.

[0024] The guiding pressure-bearing structure 4 includes two fixed piles 41 and a pressure-bearing ring 42. The two fixed piles 41 are symmetrically arranged in the stable strata on both sides of the design centerline of tunnel 1, located at the bottom of both sides of tunnel 1. The fixed piles 41 are embedded in the stable strata to a depth of not less than 8m to ensure that the fixed piles 41 have sufficient bearing capacity and stability to withstand the load transmitted by the pressure-bearing ring 42. The fixed piles 41 are equipped with a steel cage, which can be made of HRB400 grade steel bars. The top of the steel cage extends to the top of the fixed piles 41. The fixed piles 41 can be cast with C35 concrete to ensure the strength and durability of the fixed piles 41. The pressure-bearing ring 42 is an arched structure that matches the outline of the upper half of the tunnel 1. The radius of the arch top is consistent with the tunnel excavation radius. Both ends of the pressure-bearing ring 42 are fixedly connected to the connecting seats 43 on the two fixed piles 41. The top of its arch abuts against the seepage-proof layer 32 of the water-cutting and seepage-proof structure 3. The interior of its arch is the excavation space of the tunnel 1, which is used to distribute and transfer the weight of the overlying soil and the pressure of the surrounding rock to the fixed piles 41, and then to the stable strata, thus limiting the deformation of the tunnel arch.

[0025] In some embodiments, to facilitate the construction, installation, and subsequent maintenance of the pressure ring 42, the pressure ring 42 adopts an assembled structure, specifically including multiple arc-shaped plates 421, a first insert plate 422, a first slot 423, a second insert plate 424, and a second slot 425. The multiple arc-shaped plates 421 are connected end-to-end to form a semi-circular structure, i.e., the main body of the pressure ring 42. The number of arc-shaped plates 421 can be determined according to the span of the pressure ring 42. The arc-shaped plates 421 can be made of Q355B steel plate, and the curvature of the arc-shaped plates 421 is consistent with the curvature of the upper half-section of the tunnel, ensuring a tight fit between the pressure ring 42 and the tunnel profile. Reinforcing ribs can be provided inside the arc-shaped plates 421, evenly distributed radially along the arc-shaped plates 421 to enhance the rigidity and load-bearing capacity of the arc-shaped plates 421 and prevent bending deformation. The first insert plate 422 is located on one side of the arc-shaped plate 421 and is vertically fixed to the arc-shaped plate 421. It is made of the same steel plate as the arc-shaped plate 421. The first slot 423 is located at the bottom of the first insert plate 422 and is a rectangular slot with a width matching the thickness of the second insert plate 424. The second insert plate 424 is located on the other side of the arc-shaped plate 421 and is vertically fixed to the arc-shaped plate 421. It is made of the same steel plate as the arc-shaped plate 421, and its width is the same as the width of the arc-shaped plate 421. The second insert plate 424 is inserted into the first slot 423. The second slot 425 is located at the top of the second insert plate 424 and is a rectangular slot with a width matching the thickness of the first insert plate 422. The inner wall of the slot has anti-slip textures and is inserted into the first insert plate 422. When two adjacent arc-shaped plates 421 are connected, the first insert plate 422 is inserted into the second slot 425, and the second insert plate 424 is inserted into the first slot 423, forming a bidirectional insertion structure, which can be fixed by bolts to ensure the stability and sealing of the connection.

[0026] In some embodiments, the advanced support structure 2 includes multiple outer reinforcing rods 21 and multiple inner reinforcing rods 22. The multiple outer reinforcing rods 21 are symmetrically arranged on both sides of the tunnel 1, and the multiple inner reinforcing rods 22 are arranged between the multiple outer reinforcing rods 21, uniformly distributed in an arc shape along the outer side of the excavation outline of the tunnel 1. Both the outer reinforcing rods 21 and the inner reinforcing rods 22 are arranged in a 1.5m × 1.5m staggered pattern. Both the outer reinforcing rods 21 and the inner reinforcing rods 22 can be sleeved. The valve pipe has an outer reinforcing rod 21, which is formed by injecting a cement-water glass double-liquid grout and solidifying it. The water glass has a glass density of 35 and a modulus of 2.4. The initial grouting pressure is 0.3 MPa and the final pressure is 2.5 MPa. The inner reinforcing rod 22 is formed by injecting a 0.9:1 cement single-liquid grout and solidifying it. The initial grouting pressure is 0.3 MPa and the final pressure is 2.0 MPa. Through the penetration and solidification of the grout, it is tightly connected to the surrounding rock outside the tunnel 1, thus forming an integral whole with the surrounding rock and improving the self-stabilizing ability of the surrounding rock.

[0027] In some embodiments, the outer reinforcing rod 21 and the inner reinforcing rod 22 are arranged at an angle of 30°-60° with the tunnel excavation outline. The arrangement angle of the outer reinforcing rod 21 is greater than that of the inner reinforcing rod 22, ensuring that the outer reinforcing rod 21 and the inner reinforcing rod 22 can penetrate into stable strata, thereby achieving comprehensive and uniform reinforcement of the surrounding rock of the tunnel 1 arch and sidewall, forming a reinforcement ring, and improving the self-stabilizing ability of the surrounding rock.

[0028] In some embodiments, the water-cutting and seepage-proof structure 3 includes a water-cutting curtain 31, a seepage-proof layer 32, and a drainage component 33. The water-cutting curtain 31 is located between the advanced support structure 2 and the seepage-proof layer 32, forming a continuous water-stop body around the excavation outline of the tunnel 1. The water-cutting curtain 31 is formed by high-pressure jet grouting piles or cement-soil mixing piles to ensure that the water-cutting curtain 31 has good water-cutting performance and can effectively block the seepage of groundwater from the advanced support structure 2 to the seepage-proof layer 32.

[0029] The impermeable layer 32 is laid closely to the surface of the tunnel 1 excavation outline, inside the cutoff curtain 31, and is used to further block groundwater infiltration and prevent groundwater from entering the tunnel excavation space. The impermeable layer 32 can be made of HDPE geomembrane composite waterproof board. The density of HDPE geomembrane is 0.94-0.96 g / cm³. The surface of the waterproof board can be provided with anti-slip particles to increase the friction with the initial tunnel support and prevent the waterproof board from sliding. The impermeable layer 32 can be laid by hot welding. During the laying process, it is ensured that the waterproof board is undamaged and wrinkle-free. The drainage component 33 is located on the outside of the impermeable layer 32, between the cutoff curtain 31 and the impermeable layer 32, and is evenly distributed along the tunnel axis and circumferentially. It is connected to the surface drainage system to discharge the small amount of groundwater that seeps through the cutoff curtain 31 in time and prevent groundwater from accumulating in the gaps. The drainage component 33 includes circumferential and longitudinal drainage components. The circumferential drainage component uses perforated corrugated pipes with multiple drainage holes arranged in a quincunx pattern on the sidewalls. The circumferential drainage component is laid along the tunnel circumference with a spacing of 2-3 meters. The longitudinal drainage component also uses perforated corrugated pipes and is laid along the tunnel axis. The longitudinal and circumferential drainage components are interconnected to form a drainage network. The drainage component 33 is wrapped with geotextile, specifically non-woven geotextile, to prevent soil particles from entering the corrugated pipes and clogging the drainage holes, thus ensuring the drainage efficiency of the drainage component 33.

[0030] In some embodiments, the self-control structure 5 includes a drive component 51, prestressed anchor cables 52, a protective sleeve 53, and settlement monitoring points. The drive component 51 is located on the ground and is a power output component. The drive component 51 can be a cluster of intelligent tensioning jacks with servo motors and force / displacement dual feedback, which can realize synchronous and asynchronous high-precision tensioning of multiple prestressed anchor cables 52. One end of the prestressed anchor cable 52 is connected to the output shaft of the drive component 51, and the other end is fixedly connected to the top of the pressure ring 42 through an anchor, for applying prestress and adjusting the stress state of the pressure ring 42. Steel strands can be used, and the protective sleeve 53 can be made of Φ50mm PVC pipe. The protective sleeve 53 is embedded in the water-cutting and seepage-preventing structure 3 and is permeated with prestressed anchor cables 52 to protect the prestressed anchor cables 52 from being worn by grout or soil in the water-cutting and seepage-preventing structure 3, and to prevent groundwater corrosion of the prestressed anchor cables 52. Multiple settlement monitoring points are set at equal intervals along the top contour of the pressure ring 42. The settlement monitoring points 55 can be fiber optic grating settlement sensors, which can monitor the settlement and deformation of the pressure ring 42 in real time, and at the same time monitor the settlement of the surrounding rock. The settlement monitoring points are fixedly connected to the top of the pressure ring 42 with bolts, and the sensor probes face the surrounding rock and are in close contact with the water-cutting and seepage-preventing structure 3 to ensure the accuracy of the monitoring data. Multiple settlement monitoring points are electrically connected to the drive unit 51 to monitor the settlement of the surrounding rock and the deformation of the pressure ring 42 in real time. When the monitored value exceeds the preset range, the drive unit 51 automatically drives the prestressed anchor cable 52 to tighten, adjust the stress state of the pressure ring 42, and balance part of the surrounding rock pressure through the tension of the prestressed anchor cable 52, thereby limiting the settlement of the surrounding rock and the deformation of the pressure ring 42, and ensuring that the deformation is controlled within the design allowable range.

[0031] The self-control structure 5 not only adjusts the stress on the bearing ring 42, but also actively improves the stress state of the surrounding soil through the tension of the prestressed anchor cable 52, forming an active and passive composite reinforcement zone with the advanced grouting reinforcement zone, further enhancing the self-stabilizing ability of the surrounding rock.

[0032] like Figure 4 As shown, the present invention also provides a deformation control method for tunnels passing under shallow buried sections, implemented based on the aforementioned deformation control device for tunnels passing under shallow buried sections, to ensure deformation control effectiveness, specifically including the following steps: S1. Construction Preparation Clear surface debris from the construction area of ​​Tunnel 1, level the construction site to provide conditions for the placement of construction equipment; arrange the drilling rigs, grouting machines, concrete pouring equipment, and monitoring instruments required for construction, ensuring that the equipment is in good working order and meets construction requirements; determine the mileage, elevation, and grouting hole locations of Tunnel 1 using professional surveying instruments, complete the construction layout, and ensure that the construction positions of each structure meet the design requirements; at the same time, conduct technical briefings and safety training for construction personnel, clarify the construction process and technical requirements, and ensure construction safety and quality.

[0033] S2, Advanced Support Construction Along the outer perimeter of the tunnel 1 excavation outline, boreholes corresponding to the outer reinforcing rods 21 and inner reinforcing rods 22 are arranged in a 1.5m × 1.5m quincunx pattern. This quincunx arrangement ensures uniform reinforcement and enhances the overall self-stabilizing capacity of the surrounding rock. Drilling is performed using a drilling rig. During drilling, the borehole positions are strictly followed, and the vertical axis of the drilling rig is precisely controlled to ensure accurate orientation of the borehole pipe and grouting hole. The borehole deviation rate is controlled within 0.5% to 1% to avoid poor reinforcement due to borehole offset. The borehole diameter is controlled within 91 to 110 mm to match the diameter of the reinforcing rods. After drilling, a sleeve valve pipe can be inserted into the borehole, and the sleeve valve pipe corresponding to the outer reinforcing rod 21 is inserted into the borehole. Injecting a cement-water glass dual-liquid grout (water glass 35-40 glass density, modulus 2.4) allows for faster setting and rapid formation of a water-cutting curtain 31, blocking groundwater seepage and meeting the dual requirements of advanced support and water interception. Injecting a 0.9:1 cement single-liquid grout into the sleeve valve pipe corresponding to the inner reinforcing rod 22, which features rapid setting and high strength, quickly enhances the strength of the surrounding rock. The grouting sequence involves first injecting the two outer rows of outer reinforcing rods 21, then proceeding inwards sequentially. This sequence forms a water-cutting barrier, reducing the impact of groundwater on grout setting during subsequent grouting and ensuring effective grouting.

[0034] To further ensure the grouting effect, the grouting parameters need to be further adjusted and optimized through on-site grouting tests. Before grouting, water pressure tests should be conducted at selected points to measure parameters such as the unit water absorption of the rock strata, the porosity of the surrounding rock, the permeability coefficient, and the water inflow, providing a scientific basis for determining the grout mix ratio and diffusion radius. Specifically, the initial grouting pressure at the 21 outer reinforcement rods is 0.2~0.5MPa, and the final pressure is 2~3MPa. After the grouting pressure of a single hole reaches the final pressure, it should be maintained for more than 10 minutes to ensure that the grout fully penetrates into the pores of the surrounding rock. When all grouting holes in the entire section meet the single-hole termination conditions and the grout flow rate is less than 20~30L / min and the water absorption rate checked by water pressure is less than 1L / min, the grouting is considered complete, and the surrounding rock reinforcement effect meets the design requirements.

[0035] After the pre-support construction is completed, quality inspection is carried out by methods such as core drilling and sonic testing to test the strength and integrity of the reinforced rock mass. The compressive strength of the reinforced rock mass shall not be less than 1.5 MPa and the sonic velocity shall not be less than 1500 m / s. At the same time, the grouting fullness shall be tested, and the grouting fullness shall not be less than 90%. If the test fails, additional grouting treatment shall be carried out until the design requirements are met.

[0036] S3, Water-cutting and seepage-proof structure 3 construction Above the arch of Tunnel 1, a water-cutting curtain 31 is constructed inside the advanced support structure 2. The water-cutting curtain 31 is formed by high-pressure jet grouting piles or cement-soil mixing piles with a pile diameter of 600-800mm and a pile spacing of 400-600mm. The piles are interlocked with an interlocking length of not less than 100mm. The thickness of the water-cutting curtain 31 is 0.8-1.2m, and its height is consistent with the excavation height of Tunnel 1. The length is laid out along the tunnel axis, with each section being 10-15m long. The sections are connected by overlapping joints with an overlap length of not less than 1m.

[0037] After the cutoff wall 31 has cured to more than 50% of its design strength, drainage components 33 are installed inside the cutoff wall 31. These drainage components 33 include circumferential and longitudinal drainage components, all made of perforated corrugated pipes wrapped with geotextile. The circumferential drainage components are installed along the tunnel circumference at intervals of 2-3 meters, while the longitudinal drainage components are installed along the tunnel axis, with 2-3 components on each side of the tunnel. The longitudinal and circumferential drainage components are interconnected to form a drainage network. During the installation of the drainage components 33, it is ensured that the corrugated pipes are undamaged, the drainage holes are unblocked, the geotextile is tightly wrapped, and the drainage components 33 are tightly fitted and firmly fixed to the cutoff wall 31 to prevent slippage.

[0038] After the drainage component 33 is installed, an anti-seepage layer 32 is laid on the excavation outline of Tunnel 1. The anti-seepage layer 32 is made of HDPE geomembrane composite waterproof board. During the laying process, it is connected by hot welding. The laying sequence is from the tunnel arch to both sides to ensure that the waterproof board is tightly attached to the excavation outline without damage or wrinkles. After the laying is completed, the weld is tested by air inflation. The inflation pressure is 0.2-0.3MPa and maintained for 30 minutes. If there is no air leakage, it is considered qualified. If there is air leakage, it needs to be re-welded until it is qualified.

[0039] After the construction of the water-cutting and seepage-prevention structure 3 is completed, its water-cutting and seepage-prevention performance will be tested by water injection or pumping tests to determine the permeability coefficient of the water-cutting curtain 31. The permeability coefficient should not exceed 1×10⁻⁶. -6 The flow rate is measured in cm / s, and the waterproof performance of the seepage prevention layer 32 is tested to ensure that there is no leakage. The drainage efficiency of the drainage component 33 meets the design requirements. If the test fails, rectification is required until the design requirements are met.

[0040] S4, Construction of Guide Pressure Bearing Structure 4 Fixed piles 41 were constructed on both sides of the centerline of Tunnel 1. During the construction process, drilling rigs were first used to drill holes with a diameter consistent with the pile diameter. After the drilling depth reached the design requirements, debris in the holes was cleaned and a reinforcing cage was placed in. After the reinforcing cage was installed, C35 concrete was poured. During the pouring process, vibrators were used to compact the concrete to prevent defects such as honeycomb and pitting. After the pouring was completed, curing was carried out to ensure that the strength of the fixed piles 41 met the design requirements.

[0041] Based on the excavation outline dimensions of Tunnel 1, multiple arc-shaped plates 421 are fabricated. After the arc-shaped plates 421 are fabricated, a first insert plate 422 and a second insert plate 424 are welded to both sides, and a first slot 423 and a second slot 425 are fabricated to ensure a tight fit. A crane is used to hoist the arc-shaped plates 421 to the construction position, and they are spliced ​​sequentially from the arch top to both sides. When connecting two adjacent arc-shaped plates 421, the first insert plate 422 is inserted into the second slot 425, and the second insert plate 424 is inserted into the first slot 423, forming a bidirectional insertion structure. Then, the first insert plate 422 and the second insert plate 424 are fixedly connected using connecting bolts to ensure a secure connection. After the bearing ring 42 is spliced, its two ends are fixedly connected to the fixed pile 41 using high-strength bolts to ensure a secure connection between the bearing ring 42 and the fixed pile 41.

[0042] S5, Self-control Structure 5 Installation and Commissioning After the construction of the water-cutting and seepage-proof structure 3 is completed, a protective sleeve 53 is simultaneously embedded between the water-cutting curtain 31 and the seepage-proof layer 32, and the protective sleeve 53 protrudes from the ground to ensure that the protective sleeve 53 penetrates the water-cutting and seepage-proof structure 3 and that its axis is perpendicular to the tangent direction of the top of the pressure ring 42. After installation, water-swellable rubber is used to fill the gap between the protective sleeve 53 and the water-cutting and seepage-proof structure 3 to ensure a tight seal and prevent groundwater leakage.

[0043] After the guide pressure-bearing structure 4 passes the quality inspection, the drive component 51 is installed on the ground. The drive component 51 can be fixed by a fixed bracket, which is made of Q355B grade steel plate.

[0044] One end of the prestressed anchor cable 52 is fixed to the output end of the drive component 51 using a clamp-type anchor. The other end of the prestressed anchor cable 52 is passed through the protective sleeve 53 and extended to the top of the pressure ring 42. It is then fixedly connected to the anchor plate at the top of the pressure ring 42 using a clamp-type anchor. The anchor plate is firmly welded to the pressure ring 42 to ensure that the prestressed anchor cable 52 does not slip or loosen after tensioning.

[0045] Settlement monitoring points are installed at equal intervals along the top contour of the pressure ring 42. These points can be fixed to the top of the pressure ring 42 with bolts. The sensor probes should face the surrounding rock and be in close contact with the seepage prevention layer 32 of the water-cutting and seepage-prevention structure 3 to ensure the accuracy of the monitoring data. After installation, the sensor probes should be cleaned to prevent debris from obstructing the monitoring results. The settlement monitoring points can be electrically connected to an external controller, which in turn is electrically connected to the drive unit 51. The controller analyzes and processes the data fed back from the settlement monitoring points, thereby controlling the corresponding actions of the drive unit 51.

[0046] Debug the self-control structure 5 to ensure that all components are working properly. During the debugging process, simulate the deformation of the surrounding rock and check the working status of the drive component 51, the prestressed anchor cable 52 and the settlement monitoring point to ensure that all components work together properly and can realize real-time monitoring and dynamic control of deformation.

[0047] S6, Tunnel 1 Excavation and Support: Under the protection of the pressure ring 42, the tunnel body is excavated, and the initial support and secondary lining of the tunnel are carried out simultaneously.

[0048] After the self-control structure 5 has been successfully commissioned, tunnel 1 excavation will commence. The excavation method will be the bench method, selected based on the tunnel cross-section shape and geological conditions. During excavation, the tunnel excavation outline will be strictly followed, and the guiding and positioning function of the guide bearing structure 4 will be used to prevent over-excavation or under-excavation.

[0049] After tunnel excavation, initial support construction begins immediately. First, the tunnel excavation outline is cleared, loose rock and soil are removed, and then the first layer of shotcrete is applied. Following shotcreting, a steel arch frame is installed. The steel arch frame uses I16-I20 I-beams, and is fixedly connected to the bearing ring 42 using connecting plates made of Q355B grade steel to ensure coordinated stress distribution between the steel arch frame and the guide bearing structure 4. After the steel arch frame is installed, anchor bolts are installed using HRB400 grade steel bars. One end of the anchor bolt is inserted into the surrounding rock, and the other end is fixedly connected to the steel arch frame. Then, a second layer of shotcrete is applied to encase the steel arch frame and anchor bolts. Curing is then carried out after shotcreting.

[0050] During tunnel excavation and initial support construction, the self-control structure 5 monitors the surrounding rock settlement, bearing ring 42 deformation, and initial support stress in real time, collecting monitoring data every 10-30 minutes and transmitting it to the controller for analysis and processing. When the monitoring data is less than the warning value, the current construction speed and support parameters are maintained; when the monitoring data is close to the warning value, the excavation speed is reduced to 0.3-0.5 m / d, the spacing of the steel arch frames is adjusted to 0.8-1.0 m, and the drive component 51 is activated to appropriately increase the tension of the prestressed anchor cable 52 and apply support force in advance; when the monitoring data exceeds the warning value, the excavation operation is immediately stopped, emergency reinforcement measures are initiated, the tension of the prestressed anchor cable 52 is increased to the design maximum value, and temporary supports are added. Construction can only continue after the monitoring data recovers to below the warning value.

[0051] After the initial support and curing reaches more than 80% of the design strength, and the deformation of the surrounding rock of the tunnel tends to stabilize and the settlement rate is less than 0.5 mm / d for 7 consecutive days, the secondary lining construction is carried out.

[0052] The secondary lining construction uses integral steel formwork, with formwork dimensions matching the tunnel cross-section shape. A steel support system ensures the formwork is firmly installed and has sufficient rigidity, preventing deformation and displacement during construction. After installation, the formwork axis, elevation, and flatness are checked. Once approved, an isolation layer is laid between the formwork and the waterproof layer to prevent adhesion between the formwork and the secondary lining.

[0053] The secondary lining uses C35 cast-in-place concrete, poured symmetrically from the tunnel bottom to the arch crown, with a pouring speed controlled at 2-3 m³ / h to avoid defects such as segregation, honeycombing, and pitting. During pouring, a vibrator is used to compact the concrete in layers until the surface no longer settles, no more air bubbles appear, and cement slurry rises to the surface, avoiding over-vibration or under-vibration. Grouting is supplemented at the arch crown using a grouting pipe to ensure the arch crown concrete is fully poured and free of voids.

[0054] After the secondary lining concrete is poured, it should be cured promptly, using either water spraying or film covering. During curing, the temperature difference between the concrete surface and the ambient temperature should be controlled to be no more than 25°C to prevent cracking. When the concrete strength reaches more than 70% of the design strength, sealant is filled into the protective sleeve 53, and the sleeve is continuously raised to allow the sealant to solidify, forming a seal at the corresponding opening of the protective sleeve 53 in the cutoff curtain 31. Then, concrete is filled into the protective sleeve 53, and the sleeve is continuously raised to ensure that the solidified concrete, prestressed anchor cable 52, cutoff curtain 31, outer reinforcing rod 21, and inner reinforcing rod 22 form a unified whole, thus achieving a seal at that point. The formwork can only be removed when the concrete strength reaches more than 70% of the design strength. The formwork removal sequence is from the arch top to both sides and from top to bottom. During the removal process, avoid collisions with the secondary lining structure to prevent structural damage. After demolding, the surface of the secondary lining is repaired to remove burrs and laitance, ensuring a flat and smooth surface.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A deformation control device for a tunnel underpassing a shallow buried section, comprising a tunnel (1), characterized in that: It also includes an advanced support structure (2), which is installed in the rock and soil mass surrounding the arch and sidewall of the tunnel (1) to pre-reinforce the surrounding rock of the tunnel (1) and enhance the self-stabilizing ability of the surrounding rock; Water-cutting and seepage-proof structure (3), the water-cutting and seepage-proof structure (3) is set between the advanced support structure (2) and the tunnel (1) to block groundwater seepage and prevent soil saturation and softening; The guiding pressure bearing structure (4) is located on the radial inner side of the water interception and seepage prevention structure (3) and surrounds the upper half section of the tunnel (1) to guide and position the outline of the tunnel (1), while bearing the surrounding rock pressure and restricting the deformation of the tunnel (1). The self-control structure (5) is provided on the guide bearing structure (4) to realize adaptive control of deformation; The guiding pressure-bearing structure (4) includes two fixed piles (41), which are symmetrically arranged in the stable strata on both sides of the design centerline of the tunnel (1); The pressure ring (42) is an arched structure. Both ends of the pressure ring (42) are fixedly connected to the two fixed piles (41). The top of its arch abuts against the water-cutting and seepage-proof structure (3). The interior of its arch is the excavation space of the tunnel (1), which is used to distribute the upper load to the fixed piles (41).

2. A deformation control device for tunneling under a shallow buried section according to claim 1, characterized in that: The advanced support structure (2) includes multiple outer reinforcing rods (21), which are symmetrically arranged on both sides of the tunnel (1); Multiple inner reinforcing rods (22) are arranged between multiple outer reinforcing rods (21), and the multiple outer reinforcing rods (21) and the multiple inner reinforcing rods (22) are connected to the surrounding rock outside the tunnel (1).

3. The deformation control device for tunneling under shallow buried section according to claim 1, characterized in that: The water-cutting and seepage-proof structure (3) includes a water-cutting curtain (31), which is located between the advanced support structure (2) and the tunnel (1) to form a continuous water-stopping body; An impermeable layer (32) is laid in close contact with the excavation profile surface of the tunnel (1); Drainage component (33) is provided on the outside of the impermeable layer (32) and is connected to the surface drainage system.

4. A deformation control device for tunneling under a shallow buried section according to claim 3, characterized in that: The cutoff curtain (31) is formed by high-pressure jet grouting piles or cement-soil mixing piles; the seepage prevention layer (32) is made of HDPE geomembrane composite waterproof board; the drainage component (33) includes perforated corrugated pipes arranged in the circumferential and longitudinal directions, which are wrapped with geotextile.

5. A deformation control device for tunneling under a shallow buried section according to claim 1, characterized in that: The self-control structure (5) includes a drive unit (51), which is located on the ground; Prestressed anchor cable (52), one end of which is connected to the output end of the drive member (51), and the other end is fixedly connected to the top of the pressure ring (42); The protective sleeve (53) is embedded in the water-cutting and seepage-proof structure (3) and is provided with the prestressed anchor cable (52) through it. Multiple settlement monitoring points are set at equal intervals along the top contour of the pressure ring (42) and are all electrically connected to the drive component (51) to monitor the settlement deformation of the surrounding rock in real time.

6. The deformation control device for tunnels passing under shallow buried sections according to claim 1, characterized in that: The pressure-bearing ring (42) includes multiple arc-shaped plates (421), which are connected end to end to form a semi-circular structure; The first insert plate (422) is disposed on one side of the arc-shaped plate (421); The first slot (423) is located at the bottom of the first insert plate (422); The second insert plate (424) is located on the other side of the arc plate (421) and is inserted into the first slot (423); The second slot (425) is located on the top of the second insert plate (424) and is inserted into the first insert plate (422).

7. A method for controlling deformation of a tunnel passing under a shallow buried section, implemented based on the deformation control device for tunnels passing under shallow buried sections according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Construction Preparation: Clear debris from the surface of the tunnel (1) construction area, level the construction site, set up construction equipment and monitoring instruments, determine the mileage, elevation and grouting hole location of the tunnel (1), and complete the construction layout. S2. Advanced support construction: Along the outer perimeter of the tunnel (1) excavation outline, construct the aforementioned advanced support structure (2) to pre-reinforce the loose surrounding rock in the shallow buried section; S3, Construction of water-cutting and seepage-proof structure (3): Above the arch of the tunnel (1), a water-cutting curtain (31) is constructed inside the advanced support structure (2), and an anti-seepage layer (32) and drainage components (33) are laid on the excavation outline. S4, Construction of the guiding pressure-bearing structure (4): Fixed piles (41) are constructed on both sides of the centerline of the tunnel (1), and then pressure rings (42) are installed between the fixed piles (41) to form a stable arch support system; S5. Installation and debugging of the self-control structure (5): The self-control structure (5) is installed on the pressure ring (42) and then debugged. S6, Tunnel (1) Excavation and Support: Under the protection of the pressure ring (42), the tunnel body is excavated, and the initial support and secondary lining of the tunnel are carried out simultaneously.

8. The deformation control method for tunnels passing under shallow buried sections according to claim 7, characterized in that: In S3, after installing the pressure ring (42), the adaptive control structure (5) is installed simultaneously, the prestressed anchor cable (52) is connected between the drive component (51) and the pressure ring (42), and multiple settlement monitoring points are set up.

9. The deformation control method for tunnels passing under shallow buried sections according to claim 8, characterized in that: During the entire tunnel construction and operation, deformation and stress data of the bearing ring (42) are collected in real time through multiple settlement monitoring points. When the data exceeds the warning value, the drive component (51) is automatically or manually controlled to dynamically compensate the support state of the bearing ring (42) by adjusting the tension of the prestressed anchor cable (52) in order to control the deformation of the tunnel structure.

10. A method for controlling deformation of a tunnel passing under a shallow buried section according to claim 7, characterized in that: In S2, the outer reinforcing rod (21) and the inner reinforcing rod (22) are arranged in a 1.5m×1.5m quincunx pattern with corresponding drill holes, and the corresponding grout is injected respectively. The grouting sequence is to inject the outer side first, and then inject the grout inward in sequence.

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