An ultra-deep buried large-section rectangular pipe and a design and construction method thereof

Abstract

The application relates to an ultra-deeply-buried large-section rectangular top pipe and a design and construction method thereof. The design method comprises the following steps: clearly defining the geological and hydrological features and engineering constraints under the conditions of ultra-deep burial, high water pressure and soft stratum; constructing a multi-target optimization model by dynamically defining core parameters including the side wall height, the inner arc surface radius of a transition circular arc and / or the inner arc surface radius of an arch top large circular arc, screening the global optimal section parameter by adopting a parameter combination enumeration method and three-dimensional mechanical simulation, and determining the ring width and the wedge amount to form a complete section parameter system; based on the section parameter and the working condition requirement, planning a pipe joint block scheme, designing a composite structure of a longitudinal joint and a ring joint, reserving a gap for injecting modified epoxy paste, screening core materials, classifying and setting grouting holes and hoisting holes, and constructing a multi-channel waterproof system relying on the core materials to adapt to the ultra-deeply-buried high water pressure working condition. The design parameters of the top pipe are determined based on the above design method, and then the top pipe is obtained by implementing the corresponding construction method.

Description

Technical Field

[0001] This invention relates to the field of underground engineering pipe jacking construction technology, and in particular to an ultra-deep buried large-section rectangular pipe jacking method and its design and construction method. Background Technology

[0002] With the accelerating pace of urbanization and the deepening development and utilization of underground space, large-scale underground projects such as subway tunnels and underground utility tunnels are rapidly developing towards larger cross-sections, longer distances, and higher water pressure. Rectangular pipe jacking technology, as an important construction method for underground engineering, is gradually becoming the preferred solution for constructing ultra-deep (overburden depth ≥ 10m) and large-section (outer contour dimensions 12.0m × 8.7m) underground structures under complex geological conditions due to its advantages such as high space utilization, good construction efficiency, and superior forming quality. This technology uses jacking equipment to gradually advance prefabricated pipe sections to form a continuous underground structure, and is particularly suitable for subway tunnels and underground utility tunnels in water-rich, soft strata (such as silty clay and silty sand strata).

[0003] For example, CN120402109A discloses a prestressed non-circular shield tunnel structure and its construction method, belonging to the field of pipe jacking tunnel structure technology. This shield structure includes pipe sections, a central partition wall, and a prestressing system. Each pipe section comprises a first pipe section and a second pipe section with identical structural forms; the prestressing system is divided into a circumferential prestressing system and a longitudinal prestressing system. During construction, the first and second pipe section sections are assembled into a pipe section using a central rotation and longitudinal joint positioning rods, and a circumferential prestressing system is applied. Then, multiple pipe sections are assembled into a continuous pipe section using a staggered joint assembly method and mortise and tenon joints on the circumferential joint surface, and a longitudinal prestressing system is applied. Finally, a central partition wall is installed in the middle of the pipe section to form the shield structure.

[0004] However, with the expansion of project scale and the increasing complexity of geological conditions, existing rectangular pipe jacking technology faces numerous technical bottlenecks under ultra-deep burial, high water pressure, and soft strata conditions: In ultra-deep burial conditions (e.g., overburden depth of 11.2~22.5m), the pipe section structure must withstand enormous water and soil pressure, and traditional design methods are insufficient to meet structural strength requirements, manifesting as excessive pipe section deflection (exceeding the specification limit of 1 / 400L), insufficient bending resistance, and stress concentration at joints; in high water pressure environments (maximum pressurized head of 32m), leakage is prone to occur at pipe section joints, and existing sealing technologies suffer from insufficient compression of rubber gaskets, unstable grouting material performance, and simplistic joint construction; during long-distance jacking (maximum 252m), the jacking thrust... As the jacking distance increases significantly (up to a maximum of 114029.4 kN), pipe section damage is easily caused. Furthermore, the attitude control of the jacking pipe is difficult in soft strata, and the axial deviation is difficult to meet the accuracy requirements (±50 mm). There is a contradiction between controlling the excavation area of ​​large-section jacking pipes and structural lightweighting, making it difficult to optimize cross-sectional parameters and reduce material usage without affecting structural safety. In addition, the control of disturbance to the surrounding environment during construction (including surface settlement, groundwater protection, and protection of existing structures) also faces severe challenges. In particular, when ultra-deep buried large-section jacking pipes pass sideways or under existing sensitive buildings and structures, the excavation unloading and grouting pressure can easily cause additional internal forces or even uneven settlement of adjacent bridges and their pile foundations, which urgently needs to be addressed.

[0005] Furthermore, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the applicant studied a large number of documents and patents when making this invention, but due to space limitations, not all details and contents were listed in detail. However, this does not mean that the present invention does not possess the features of these prior art. On the contrary, the present invention already possesses all the features of the prior art, and the applicant reserves the right to add relevant prior art to the background art. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the present invention provides an ultra-deep buried large-section rectangular jacking pipe and its design and construction method, so as to solve at least some of the above-mentioned technical problems.

[0007] In a first aspect, the present invention discloses a design method for ultra-deep buried large-section rectangular jacking pipe, which includes: S1. Clarify the geological and hydrological characteristics and engineering constraints under conditions of ultra-deep burial, high water pressure, and weak strata; S2. By dynamically defining core parameters including sidewall height, radius of the inner arc surface of the transition arc and / or radius of the inner arc surface of the arch crown, a multi-objective optimization model is constructed. The parameter combination enumeration method and three-dimensional mechanical simulation are used to screen the globally optimal section parameters and determine the ring width and wedge amount to form a complete section parameter system. S3. Based on the cross-sectional parameters and working conditions, plan the pipe section segmentation scheme, design the composite structure of longitudinal joints and circumferential joints, and reserve gaps for injection of modified epoxy grout. S4. Select core materials, classify and set grouting holes and hoisting holes, and build a multi-layer waterproof system based on core materials to adapt to ultra-deep buried high water pressure conditions.

[0008] According to a preferred embodiment, in step S2, the optimization objectives of the multi-objective optimization model include structural safety objectives, economic objectives, stress balance objectives, and construction adaptation objectives. Among them, the structural safety objective is to ensure that the maximum deflection of the pipe section structure under ultra-deep burial conditions does not exceed a preset deformation threshold; the economic objective is to control the excavation area of ​​the pipe jacking to not exceed a preset area threshold; the stress balance objective is to ensure that the bending moment values ​​at the top, bottom, and corners of the pipe section are less than the threshold and are evenly distributed; and the construction adaptation objective is to ensure that the weight and size of the pipe section corresponding to the optimized cross-sectional parameters match the carrying capacity of the transportation path and the tonnage of the hoisting equipment.

[0009] According to a preferred embodiment, in step S2, the optimization solution and verification are performed by using three-dimensional mechanical simulation software to perform standardized performance verification on feasible cross-section combinations, and then the final optimal cross-section parameters are determined by using a method of local extreme value screening combined with global optimal verification. The standardized performance verification is based on typical load combinations under ultra-deep burial conditions.

[0010] According to a preferred embodiment, in step S2, the ring width and wedge amount are comprehensively determined by combining the prefabrication and transportation capacity of the pipe section, the bearing capacity of the hoisting equipment, and the planar alignment characteristics of the jacking section. The ring width and wedge amount, together with the sidewall height, the inner arc radius of the transition arc, and the inner arc radius of the arch crown, constitute a complete cross-sectional parameter optimization framework.

[0011] According to a preferred embodiment, in step S3, the composite structure of the longitudinal joint includes an F-type socket structure, a tongue and groove anti-shear structure, and a high-strength bolt anti-bending structure. The F-type socket structure is formed by the tenon and groove at the end of the pipe section segment. The tongue and groove anti-shear structure is arranged on the inner and outer sides of the F-type socket structure. The high-strength bolt anti-bending structure is evenly arranged along the longitudinal joint.

[0012] According to a preferred embodiment, in step S3, the composite structure of the circumferential joint includes a CT bolt connection and a tenon structure. The CT bolt connection uses a ring connector as the core load-bearing component, and the tenon structure is designed in conjunction with the tongue and groove tenon structure of the longitudinal joint.

[0013] According to a preferred embodiment, in step S4, the core materials selected include main structural materials, joint load-bearing materials, and sealing and waterproofing materials. The main structural materials are high-performance concrete, the joint load-bearing materials include high-strength bolts and pre-embedded steel sleeves, and the sealing and waterproofing materials include waterproof sealing gaskets (including EPDM rubber sealing gaskets and water-swellable rubber sheets) and wedge-shaped rubber rings (the material of which can be neoprene rubber).

[0014] According to a preferred embodiment, in step S4, the multi-layer waterproofing system includes structural self-waterproofing, joint main sealing, gap grouting waterproofing, and emergency waterproofing. The structural self-waterproofing relies on the density of the main structural material. The joint main sealing uses a sealing waterproofing material. The gap grouting waterproofing fills the joints and the gaps between the tongue and groove with modified epoxy grout. The emergency waterproofing is achieved by configuring a quick-setting dual-liquid grout through the reserved grouting holes on the inner side.

[0015] This invention's design method, through the synergistic effect of systematic technical features, achieves comprehensive optimization of structural safety, construction feasibility, and long-term service performance of ultra-deep buried large-section rectangular pipe jacking under complex geological conditions. First, S1 clarifies the geological and hydrological characteristics and engineering constraints of ultra-deep burial, high water pressure, and soft strata, providing a precise basis for subsequent design and ensuring the scheme is suitable for stringent conditions such as overburden depth ≥10m and confined water head ≥20m. Based on this, S2 dynamically defines core parameters such as sidewall height, the radius of the inner arc of the transition arc, and the radius of the inner arc of the arch crown, constructing a multi-objective optimization model encompassing structural safety, economy, stress balance, and construction adaptability. This model combines parameter combination enumeration with three-dimensional mechanical simulation to screen for the globally optimal cross-sectional parameters. Among these objectives, structural safety is achieved by controlling the maximum deflection of the pipe section to not exceed a preset deformation threshold (e.g., L / 400) to avoid cracking risks; economic efficiency is achieved by limiting the excavation area to not exceed a threshold to reduce ground disturbance and material usage; stress balance is achieved by evenly distributing bending moments at the top, bottom, and corners of the pipe section to prevent local sections from exceeding the ultimate bearing capacity of concrete; and construction compatibility is achieved by matching the weight of the pipe section with the capacity of the hoisting equipment to avoid transportation and well-drilling risks. Furthermore, three-dimensional mechanical simulation software performs standardized performance calculations based on typical load combinations (water and soil pressure, jacking force, etc.), and determines cross-sectional parameters through local extreme value screening and global optimal verification to ensure the universality of the optimization results under different working conditions. The determination of the ring width and wedge amount, combined with the prefabrication and transportation capacity of the pipe section, hoisting conditions, and alignment characteristics, forms a complete cross-sectional parameter optimization framework. This ensures that the 1.5m wide pipe section is compatible with the load-bearing requirements of the hoisting equipment, and also compensates for the error in the broken line fitting through the design of the wedge amount in the curved section, improving the axial accuracy. In the joint construction design, the longitudinal joint adopts an F-type socket structure to achieve rapid positioning and adaptation to small angles. The tongue and groove shear-resistant structure transmits shear force through mechanical interlocking, preventing the bolts from bearing excessive shear failure alone. The 10.9 grade high-strength bolt bending-resistant structure forms an integral force system through pre-tightening force, effectively transmitting negative bending moment. The circumferential joint uses CT bolt connection and tenon structure in synergy. The CT bolts, with 360° uniform force distribution, improve shear force transmission efficiency. The tenon structure restricts radial displacement and, together with the filling grouting holes and tenon groove grouting holes, injects modified epoxy grout to eliminate stress concentration, jointly enhancing the integrity and waterproof performance of the joint. The selection of core materials and the construction of a multi-layered waterproofing system further enhance structural reliability: high-performance concrete (C50 / P10-P12) provides density and impermeability, 10.9 grade high-strength bolts and Q355 pre-embedded steel sleeves ensure the force transmission of joints, waterproof sealing gaskets and wedge-shaped rubber rings form water-facing protection, while modified epoxy grout filling gaps and quick-setting dual-liquid grout emergency waterproofing construct a four-fold closed-loop system of structural self-waterproofing, joint sealing, gap grouting and emergency protection.The integrated application of the above features enables the pipe jacking structure to achieve deflection control, stress balance, reliable joint transmission, and multiple waterproof protection under ultra-deep buried high water pressure conditions. At the same time, it takes into account the efficiency of construction transportation and assembly, and solves the technical bottlenecks in traditional design such as parameter dependence on single working conditions, insufficient shear and bending resistance of joints, and single failure of waterproof system. It provides scientific and precise design method support for ultra-deep buried large-section underground engineering under complex geological conditions.

[0016] Secondly, this invention discloses an ultra-deep buried large-section rectangular jacking pipe, which is designed using the aforementioned design method to determine the design parameters.

[0017] The ultra-deep buried large-section rectangular pipe jacking structure designed in this invention employs design parameters determined by the aforementioned design method, enabling the pipe section structure to possess excellent structural safety and waterproofing performance under ultra-deep buried high water pressure conditions. Through optimized design of cross-sectional geometric parameters, the deflection of the pipe section structure is ensured to be controlled within a reasonable range under ultra-deep buried conditions, preventing cracking due to excessive deflection. The composite structural design of longitudinal and circumferential joints ensures reliable shear force transmission and deformation adaptability at the joints, preventing structural damage due to joint failure. The construction of a multi-layered waterproofing system achieves the synergistic effect of structural self-waterproofing, joint sealing, and gap grouting, ensuring no leakage under high water pressure. This pipe jacking structure, while meeting structural safety requirements, also considers construction feasibility and long-term service performance, making it suitable for ultra-deep buried large-section underground engineering projects under complex geological conditions.

[0018] Thirdly, this invention discloses a construction method for the aforementioned ultra-deep buried large-section rectangular pipe jacking, which includes one or more of the following steps: Based on geological and hydrological characteristics and surrounding environmental constraints, a water-stop curtain combined with high-pressure reinforcement technology was used to treat the end soil, and a dewatering system was constructed simultaneously to control the groundwater level below the design safety threshold, which is suitable for construction needs in high-risk strata. Based on the optimized cross-sectional parameters, the excavation dimensions of the pipe jacking machine and the reference of the starting bracket are calibrated. The bracket is raised according to the pre-set slope to prevent posture deviation and to adapt to the cross-sectional stress and construction safety design requirements. According to the design block plan, the pipe sections are hoisted and positioned first through the F-type socket structure during docking, and then the longitudinal / circumferential composite joint is assembled by tightening high-strength bolts. The joint gap is reserved for filling grout to ensure that the block collaborative stress design is implemented. The single-ring jacking length is controlled according to the designed ring width. Parallel assembly is adopted for straight sections, and the inter-ring gap is adjusted according to the designed wedge amount for curved sections. During tunneling, the excavation face pressure is dynamically adjusted based on the deformation control target to adapt to the cross-section line and structural safety design. The design incorporates a multi-layered waterproofing system. Before the pipe sections are assembled, sealing components are laid. After assembly, modified epoxy grout is injected through filling grouting holes and tenon grouting holes to form a closed-loop protection system that combines structural self-waterproofing, joint sealing, and gap grouting, making it suitable for high water pressure waterproofing designs. When crossing sensitive areas, monitoring is intensified according to the design deformation control threshold, controllable parameters are adjusted synchronously, and grouting behind the wall is strengthened to compensate for stratum deformation and adapt to the surrounding environmental protection design constraints. During the receiving phase, the receiving base and anti-collision device are installed according to the design alignment. After calibrating the position of the tunnel portal, the pipe jacking machine is advanced with low disturbance. The tunnel portal is sealed and the equipment is separated to ensure that the pipe section axis meets the design requirements. After the jacking is completed, the wall grout replacement, joint caulking of pipe sections and sealing of reserved holes are carried out to complete the subsequent reinforcement and waterproofing finishing, so as to achieve the goals of long-term structural stability and waterproofing reliability in the design method.

[0019] The ultra-deep buried large-section rectangular pipe jacking construction method adopted in this invention effectively controls the groundwater level by treating the end soil with a water-stop curtain combined with high-pressure reinforcement technology and simultaneously constructing a dewatering system, thus providing a safe environment for construction in high-risk strata. The excavation dimensions of the pipe jacking machine and the starting support reference are calibrated according to the optimized cross-sectional parameters, and the support is raised according to the pre-designed slope to effectively prevent deviations in the pipe jacking posture. Pipe sections are hoisted according to the designed segmented scheme and positioned first using a socket-type structure, then high-strength bolts are tightened to complete the composite joint assembly, ensuring coordinated stress distribution among the segments. The single-ring jacking length is controlled according to the designed ring width; parallel assembly is used for straight sections, and the inter-ring spacing is adjusted according to the designed wedge shape for curved sections. During the tunneling process, the excavation face pressure is dynamically adjusted based on deformation control targets to achieve axial accuracy control. A multi-layered waterproofing system is implemented, with sealing components laid before pipe section assembly and modified epoxy grout injected through filling and tenon grouting holes after assembly to form a closed-loop protection. When crossing sensitive areas, monitoring is intensified and controllable parameters are adjusted synchronously, strengthening backfill grouting to compensate for ground deformation and ensure environmental safety. During the receiving phase, receiving bases and anti-collision devices are installed according to the designed alignment, and the pipe jacking machine is advanced with low disturbance to ensure the pipe section axis meets design requirements. After jacking is completed, backfill grout replacement, joint caulking of pipe sections, and sealing of reserved holes are carried out to complete subsequent reinforcement and waterproofing. This construction method effectively achieves the design intent, ensuring safe, efficient, and reliable construction of ultra-deep buried large-section rectangular pipe jacking under complex geological conditions. Attached Figure Description

[0020] Figure 1 This is a flowchart of the design method of a preferred embodiment of the present invention; Figure 2 This is a schematic diagram of the geometric parameters of the cross-section of the jacking pipe section; Figure 3 This is a schematic diagram of the cross-sectional dimensions of the jacking pipe section after the example cross-sectional optimization design; Figure 4 This is a diagram of the internal forces and bending moments of the pipe jacking section of Line 18 under design conditions. Figure 5 This is a diagram of the axial force within the pipe section of Line 18 under design conditions. Figure 6 This is the shear force diagram of the pipe jacking section of Line 18 under the design conditions; Figure 7 This is a diagram of the internal forces and bending moments of the pipe jacking section of Line 15 under design conditions; Figure 8 This is a diagram of the axial force within the pipe jacking section of Line 15 under design conditions. Figure 9 This is the shear force diagram of the pipe jacking section of Line 15 under the design conditions; Figure 10 This is a schematic diagram of the staggered joints of the upper and lower sections of the jacking pipe segment; Figure 11 This is a schematic diagram of the longitudinal joint of the jacking pipe section; Figure 12 This is a schematic diagram of the circumferential joint of the jacking pipe section; Figure 13 This is a schematic diagram of the grouting pipe arrangement for the jacking pipe section; Figure 14 This is a schematic diagram of the wedge-shaped rubber ring and waterproof sealing gasket of the jacking pipe joint. Detailed Implementation

[0021] The following is a detailed explanation with reference to the accompanying drawings.

[0022] Example 1 like Figure 1 As shown, this invention discloses a design method for ultra-deep buried large-section rectangular jacking pipes, which includes one or more of the following steps: S1. Clarify the geological and hydrological characteristics and engineering constraints under conditions of ultra-deep burial, high water pressure, and weak strata; S2. By dynamically defining core parameters including sidewall height, radius of the inner arc surface of the transition arc and / or radius of the inner arc surface of the arch crown, a multi-objective optimization model is constructed. The parameter combination enumeration method and three-dimensional mechanical simulation are used to screen the globally optimal section parameters and determine the ring width and wedge amount to form a complete section parameter system. S3. Based on the cross-sectional parameters and working conditions, plan the pipe section segmentation scheme, design the composite structure of longitudinal joints and circumferential joints, and reserve gaps for injection of modified epoxy grout. S4. Select core materials, classify and set grouting holes and hoisting holes, and build a multi-layer waterproof system based on core materials to adapt to ultra-deep buried high water pressure conditions.

[0023] Preferably, step S1 can clarify the geological and hydrological environment, spatial functional boundaries and surrounding environmental limitations of the project through standardized processes, providing accurate basis for subsequent design stages, ensuring that the scheme is suitable for ultra-deep burial (soil cover ≥10m), high water pressure (confined water head ≥20m), and soft strata (including silty clay, sandy silt, etc.), and avoiding design disconnect due to insufficient identification of working conditions.

[0024] Preferably, layered investigation can clarify the distribution of soil layers and key physical and mechanical parameters (natural unit weight, compression modulus, foundation bearing capacity, permeability coefficient, etc.) to distinguish the occurrence layers, head characteristics, and integrity of the impermeable layer of shallow phreatic water and deep confined water, thereby assessing the risk of confined water inrush. Simultaneously, adverse geological processes (such as shallow methane and liquefied soil) can be identified, and prevention and control requirements can be determined based on the measured methane pressure (e.g., <0.05MPa indicates minimal impact) and the distribution range of liquefied soil (whether it involves the pipe jacking crossing area). For example, in the pipe jacking project of Hangzhou Metro Lines 18 and 15, the distribution of silty clay, gravel, and other soil layers was clarified through investigation, and the height of the confined water head (32m for Line 18 and 30m for Line 15) and the impact range of shallow methane and slightly liquefied soil were determined, providing a geological basis for subsequent design.

[0025] Preferably, from a spatial clearance perspective, the internal contour dimensions (width, height) and planar alignment (straight or curved, with a specific curve radius required to avoid the protected cultural relic) of the pipe jacking can be determined in conjunction with the engineering function (such as subway parking lines or utility tunnels) to ensure compatibility with equipment development and the clearance requirements of multiple lines. From a surrounding environment perspective, the horizontal / vertical distance between the pipe jacking and existing buildings (basements, protected cultural relic buildings, pipelines) can be clearly defined, and structural deformation control thresholds can be set (such as differential settlement ≤5mm in the turnout area and overall settlement ≤15mm). For example, the pipe jacking for Line 18 needs to avoid the protected cultural relic of Huajiachi, so a curved alignment is set and the pipe jacking shaft is moved westward. At the same time, due to its proximity to the basement of Kaijing Apartment (4m away), deformation is strictly controlled. The pipe jacking for Line 15, which has no special clearance constraints, adopts a straight layout.

[0026] Preferably, step S2 can determine the optimal cross-sectional parameters that are suitable for ultra-deep burial (cover depth ≥ 10m), high water pressure (confined water head ≥ 20m), and soft strata (including silty clay, sandy silt, silty sand, etc.) by defining core parameters, constructing a multi-objective optimization model, and verifying the solution. This achieves an organic unity of structural deformation control, excavation area optimization, stress state balance, and construction condition adaptation, avoiding the problem of parameter selection relying on a single project condition and poor adaptability in traditional experience-based design. It ensures that the design method can be universally applied to large-section rectangular pipe jacking projects with different functional requirements (such as subway parking lines and underground pipe corridors) and different geological conditions, providing scientific and accurate basic parameter support for subsequent pipe section structure design, waterproof system construction, and construction technology formulation.

[0027] Preferably, when dynamically defining core design variables, geometric parameters that play a decisive role in structural performance, space utilization, and construction feasibility can be selected as optimization objects based on the structural stress characteristics and engineering functional requirements of rectangular pipe jacking. Furthermore, the value range of each parameter can be dynamically adjusted according to the actual engineering conditions (such as inner contour limits, soil bearing capacity, and construction equipment capacity), rather than being fixed to a specific value. Figure 2 As shown, considering the engineering characteristics of ultra-deep buried large-section rectangular pipe jacking, the core design variables can be determined as the sidewall height H, the radius of the inner arc surface of the transition arc R2, and the radius of the inner arc surface of the large arc surface of the arch R1. Among them, the sidewall height directly affects the vertical shear resistance and internal space height of the structure, and must take into account the structure's resistance to vertical water and soil pressure and the internal functional requirements of the project (such as the need to meet the height of train carriages and the passage space for maintenance personnel in subway parking lines). Its value range can be set, for example, from 2.2m to 3.65m. The specific value can be deduced from the inner contour height limit and adjusted in conjunction with the vertical deflection calculation results of the structure. The radius of the inner arc surface of the transition arc mainly affects the stress concentration at the corner of the pipe section. If the radius is too small, it is easy to cause stress peaks at the corner, leading to cracks. If the radius is too large, it will cause stress peaks at the corner. This would encroach on the effective internal space. Its general value range can be set, for example, to 0m~2m. The optimal value can be determined by calculating the corner bending moment to ensure that the corner stress is within the safe bearing capacity of the concrete material. The radius of the inner arc surface of the arch top is directly determined by the inner contour width limit of the project. It can be determined by reverse calculation based on the minimum width required for the internal function (such as the subway parking line needing to meet the train passage width, and the additional space required for the installation of the switch machine). For example, when the project needs to meet the single crossover limit requirement, and the installation range of the switch machine and the crossover layout require the inner contour width of the jacking pipe to reach 10400mm, the radius of the inner arc surface of the arch top needs to be designed according to this width limit to ensure that the internal space fully covers the functional requirements, while avoiding unnecessary increase in the excavation area due to an excessively large radius.

[0028] Furthermore, when constructing a multi-objective optimization model, a multi-dimensional optimization objective system covering structural safety, economy, and construction feasibility can be established around the core design requirements of ultra-deep buried large-section rectangular jacking pipes. The constraint thresholds for each objective can be universally set based on industry standards, material properties, and construction equipment capabilities. Specifically, the optimization objectives can include the following four categories: The first category is deformation control objectives, ensuring that the maximum deflection of the pipe section structure under ultra-deep burial conditions is ≤1 / 400 times the structural span (i.e., ≤1 / 400L, where L is the maximum span of the jacking pipe cross-section). This threshold can be determined according to the requirements for tunnel structural deformation in the "Shield Tunnel Engineering Design Standard," effectively preventing structural cracking due to excessive deflection. The second category is economic objectives, controlling the jacking excavation area to <90m². 2The first category is to reduce the scope of ground disturbance by reducing the excavation volume, while also reducing the amount of materials such as concrete and steel bars, thereby reducing the project cost. The second category is to achieve stress balance, which can ensure that the bending moment values ​​at the top, bottom and corners of the pipe section are relatively small and evenly distributed, avoiding local sections from exceeding the ultimate bending capacity of concrete due to excessive bending moment. The bending moment at the top needs to be controlled within the ultimate bending capacity of concrete (e.g., the bending moment control value for C50 concrete is ≤2516kN·m), and the bending moment at the corners needs to avoid excessive negative bending moment that could cause tensile cracking at the corners. The third category is to achieve construction compatibility, which can ensure that the weight and size of the pipe section corresponding to the optimized cross-sectional parameters match the carrying capacity of the transportation path and the tonnage of the hoisting equipment, avoiding difficulties in transportation and lowering into the well due to excessive weight or size of the pipe section. In terms of optimization methods, the "parameter combination enumeration method" can be used to construct the solution model. For example, for three core variables, a total of 12,000 different cross-sectional parameter combinations can be generated, including the side wall height (30 sets), the radius of the inner arc surface of the transition arc (10 sets), and the radius of the inner arc surface of the arch top large arc (10 sets). Then, combined with the actual constraints of the project (such as the maximum excavation size of the pipe jacking machine and the limitation of the width of the transport vehicles on the construction site), obviously infeasible combinations (such as combinations where the excavation size exceeds the construction capacity of the pipe jacking machine) are filtered out, and feasible combinations are retained for subsequent performance verification. Figure 3 This is a schematic diagram of the cross-sectional dimensions of the jacking pipe section after the example cross-sectional optimization design.

[0029] Finally, optimization and verification are implemented. Standardized performance calculations are performed on all feasible cross-section combinations using 3D mechanical simulation software (such as ANSYS). The final optimal cross-section is then determined using a method combining local extreme value screening and global optimal verification. This ensures that the verification process does not rely on the single load conditions of a specific project, but rather on a generalized calculation based on typical load combinations (soil and water pressure, pipe section self-weight, and jacking force) under ultra-deep burial conditions. The specific steps are as follows: First, for each feasible cross-section combination, a 3D mechanical model is established, and load parameters (soil and water pressure is calculated based on the overburden depth, and jacking force is estimated based on the jacking length and ground friction) are substituted to calculate the maximum deflection, top bending moment, bottom bending moment, corner bending moment, and excavation area of ​​the cross-section. Second, within each sidewall height range, the combination of the inner radius of the transition arc and the inner radius of the arch crown's great arc that meets deformation control and economic objectives is selected to form a local optimal solution (e.g., when the sidewall height is 3.0m, the combination with the minimum deflection and excavation area <90m² is selected). 2 The first step is to compare the stress balance and construction adaptability of all local optimal solutions, and prioritize the combination with more uniform bending moment distribution at the top, bottom and corners and better suitability of pipe section weight for hoisting equipment to determine the global optimal section parameters. The second step is to verify the global optimal section by adjusting the load parameters (such as adding seismic action and differential settlement load) to test the stability of the section performance and ensure that the design requirements can be met under different working conditions.

[0030] Taking the pipe jacking project of the parking line at Huajiachi Station on Hangzhou Metro Line 18 as an example, Figures 4-6 These are the internal force bending moment diagram, internal force axial force diagram, and internal force shear force diagram of the No. 18 pipe jacking section under the design conditions. The optimization process of its cross-sectional parameters follows the above procedure: First, according to the single-crossing clearance requirements, the radius of the inner arc surface of the arch crown must meet the requirement of an inner contour width of 10400mm. Then, 12000 cross-sectional combinations are generated within the range of 2.2m~3.65m (30 groups) for sidewall height and 0m~2m (10 groups) for the inner arc surface radius of the transition arc. The performance index of each combination under 11m overburden pressure (soil and water pressure) is calculated using ANSYS software, and the sections with an excavation area <90m² are selected. 2 The combination of deflection ≤ 1 / 400L (here L = 11.2m, deflection ≤ 28mm) was considered; then, the bending moment distribution of these combinations was compared, and the globally optimal cross-sectional parameters were finally determined to be: sidewall height 3.0m, transition arc inner arc radius 1.5m, and arch crown great arc inner arc radius determined according to the clearance, corresponding to an excavation area of ​​89.8m². 2 The deflection is 18mm (≤28mm), the top bending moment is 1910kN·m, and the corner bending moment is -1498kN·m, all of which meet all optimization objectives. Furthermore, the Hangzhou Metro Line 15 pipe jacking project is a straight section, and the inner contour clearance requirements are relatively simple. Figures 7-9 These are the internal force bending moment diagram, internal force axial force diagram, and internal force shear force diagram for the No. 15 pipe jacking section under the design conditions. After optimization according to the same general process, the sidewall height is determined to be 2.8m, the radius of the inner arc surface of the transition arc is 1.2m, and the radius of the inner arc surface of the great arc of the arch is determined according to the straight-line limit. The excavation area is 88.5m². 2 The deflection is 16mm, which also meets the design requirements. This optimization process ensures that the optimal cross-sectional parameters can be obtained for ultra-deep buried large-section rectangular jacking pipes under different working conditions, while guaranteeing the universality of the design method and the protection range.

[0031] Preferably, in step S2, the ring width and wedge shape can be determined by combining the prefabrication and transportation capacity of the pipe section, the bearing capacity of the hoisting equipment, and the planar alignment characteristics of the jacking section. The rationality of its design directly affects the pipe section assembly efficiency, structural integrity, and axial accuracy. Together with the side wall height, the radius of the inner arc surface of the transition arc, and the radius of the inner arc surface of the arch, it constitutes a complete cross-sectional parameter optimization framework, ensuring that the ultra-deep buried large cross-section rectangular jacking pipe meets the structural stress requirements while adapting to the entire construction process.

[0032] Furthermore, the determination of the ring width can be based on the results of case studies, combined with a comprehensive assessment of single-section weight control, construction site transportation route load-bearing limitations, and rated lifting capacity of hoisting equipment. Research on similar engineering cases (such as the Tongxiang Wuzhen Avenue pipe jacking, the Hangzhou Sijiqing Station turnaround line pipe jacking, and the Jiaxing Nanhu municipal pipe jacking) shows that a width of 1.5m is the mainstream choice for existing large-section rectangular pipe jacking. This width allows for strong mold versatility and high production efficiency during the prefabrication of pipe sections. During transportation, the requirements for the load capacity of transport vehicles (suitable for vehicles with a load capacity of ≥100t) and the load-bearing capacity of roads and bridges are relatively low. When lowering pipe sections into the well, they can be hoisted by a conventional gantry crane (rated lifting capacity ≥60t), and the risks are controllable. If a width of 2.0m is used, although the number of assembly rings can be reduced, it will lead to a significant increase in the weight of a single pipe section (e.g., a single pipe section weighs up to 70t, and a single ring weighs up to 140t), exceeding the load-bearing limit of most construction site transportation routes (especially when transporting urban roads and bridges, it is easy to cause road damage or bridge overloading risks). In addition, the load-bearing capacity requirements of the hoisting foundation are greatly increased when lowering pipe sections into the well, the operation time is extended, and the construction risks are significantly increased. Meanwhile, the ring width needs to be compatible with the pipe segmentation scheme to ensure that the weight of a single pipe segment does not exceed 80% of the rated lifting capacity of the hoisting equipment. For example, when using a 1.5m width with a 2-segment scheme, the volume of a single pipe segment is approximately 19.39m³. 3 Based on the natural unit weight of C50 concrete of 25kN / m³ 3 Calculations show that a single pipe section weighs approximately 48.5 tons, which is suitable for gantry cranes with a rated lifting capacity of ≥60 tons, thus meeting construction safety requirements.

[0033] Furthermore, the design of the wedge amount can depend on the planar alignment of the jacking section, used to adjust the assembly gap between pipe segment rings to ensure that the axis meets the design requirements. For jacking sections with a straight planar alignment, no wedge amount is needed between pipe segment rings; pipe segments can be assembled in parallel, and the straightness of the axis is ensured through the connection structure of the circumferential joint. For jacking sections with a curved planar alignment, since the pipe segment rings need to form a broken line fitting curve along the curve radius during assembly, a wedge amount needs to be set between the pipe segment rings to compensate for the gap between the broken line and the curve, avoiding misalignment between rings or axis deviation. The specific value of the wedge amount can first be calculated according to the theoretical value specified in the "Shield Tunnel Engineering Design Standard," and then appropriately adjusted by comprehensively considering factors such as construction errors (e.g., assembly accuracy, pipe segment manufacturing errors) and stratum deformation (e.g., axis offset caused by slight settlement in soft strata).

[0034] Taking the pipe jacking projects of Hangzhou Metro Lines 15 and 18 as examples, the horizontal alignment of the pipe jacking section of Line 15 is straight, so the ring width of the pipe section is 1.5m, and no wedge is set. The weight of a single pipe section is 48.5t, which is suitable for the hoisting capacity of the on-site gantry crane. After the pipe section is assembled, the deviation of the straightness of the axis is controlled within ±5mm. The horizontal curve radius of the pipe jacking section of Line 18 is about 8335m. The ring width of the pipe section is also 1.5m. According to the specifications, the theoretical wedge amount is 2.1mm. Taking into account the construction error and the stratum deformation factors, the final wedge amount is determined to be 3mm. Through this wedge adjustment, the axis of the pipe section after the curved section is assembled meets the requirement of 8335m curve radius, and the misalignment between rings is ≤1mm, which meets the axis accuracy control requirements under ultra-deep burial conditions.

[0035] Preferably, step S3 can be based on the cross-sectional parameters (such as excavation area, sidewall height, and bending moment distribution range) determined in the previous steps and the engineering requirements (ultra-deep buried soil and water pressure, high water pressure waterproofing, and soft stratum deformation adaptation). Through the rational planning of the block scheme and the innovative structural design of the longitudinal and circumferential joints, a structural system with block collaborative force transmission, reliable joint transmission, and controllable overall deformation is constructed. This solves the technical defects of traditional rectangular pipe jacking structures, such as the disconnection of block force, insufficient shear and bending resistance of joints, and weak adaptability to stratum deformation. It ensures that the pipe section can effectively resist the positive bending moment at the top, the negative bending moment at the corner, and the inter-ring shear force during long-term service. At the same time, it meets the construction feasibility of pipe section prefabrication, transportation, hoisting, and assembly, providing key guarantees for the structural safety of ultra-deep buried large-section rectangular pipe jacking.

[0036] Preferably, a detailed plan for the segmentation of the pipe section can be developed first. The design principles revolve around adapting to construction conditions, avoiding stress concentration, and ensuring structural integrity. The number of segments, the weight of a single segment, and the location of the segments can be determined by comprehensively considering the load-bearing limitations of the transportation routes at the construction site, the rated lifting capacity of the hoisting equipment, and the stress distribution characteristics of each section of the pipe section. From a construction adaptability perspective, the segmentation must ensure that the weight and dimensions of a single segment can pass through roads, bridges, and underground passages at the construction site, and meet the safe lifting requirements of the hoisting equipment—typically, a two-segmentation scheme is adopted (e.g., ...). Figure 10 As shown, it can be divided into combinations of A1 and A2 or B1 and B2, where 2H is the staggered joint height and H is the structural position relative to the center of the structure. Under special conditions, it can be expanded to 3-4 blocks depending on site conditions. The weight of a single pipe section must be controlled within 80% of the rated lifting capacity of the hoisting equipment to avoid road damage during transportation or equipment overload during hoisting due to excessive weight of a single section. For example, the pipe jacking projects of Hangzhou Metro Lines 18 and 15 both adopted a 2-block segmentation scheme, with a pipe section width of 1.5m and a single pipe section volume of 38.78m³. 3 Based on the natural unit weight of C50 concrete of 25kN / m³ 3Calculations show that a single ring pipe section weighs approximately 96.94 tons, which is suitable for the lifting capacity of the on-site gantry crane (rated lifting capacity ≥ 120 tons) and also meets the passage requirements of transport vehicles (load capacity ≥ 100 tons) within the construction site. From the perspective of structural stress rationality, the segment locations avoid high-stress areas with large bending moments, such as the top and corners of the pipe section. The segment joints are set in sections with lower stress, such as the middle of the side wall of the pipe section, to reduce the weakening of the overall structural stress by the joints. Three-dimensional mechanical simulation analysis shows that the top of the pipe section bears the maximum positive bending moment (e.g., the bending moment at the top of the No. 18 jacking pipe is 1910 kN·m), and the corner bears the maximum negative bending moment (e.g., the bending moment at the corner of the No. 18 pipe section is -1498 kN·m). If the segment joints are set in these areas, stress concentration at the joints is likely to occur, leading to pipe section cracking. However, the bending moment value in the middle of the side wall of the pipe section is only 1 / 5 to 1 / 3 of the bending moment at the top (e.g., the bending moment in the middle of the side wall of the No. 18 pipe section is about 420 kN·m). Setting the segment joints here can effectively transfer internal forces through the rigid connection structure at the joints, ensuring the integrity of the structure. The specific joint location was determined by analyzing the relationship between the staggered joint height H and the internal forces and deflection of the pipe section through single-factor multi-objective calculation, and a reasonable staggered joint height H was selected. In addition, space must be reserved at the joints of the sections for the installation of subsequent connections and waterproof structures to ensure that the force transfer and waterproof sealing can be achieved through the joint structure after the sections are assembled, so as to avoid functional loss due to the disconnect between the section design and the joint design.

[0037] Furthermore, the longitudinal joint can be designed. As a crucial component for force transfer and deformation coordination between adjacent sections within the pipe segment ring, the longitudinal joint's design must simultaneously meet four core requirements: shear resistance, bending resistance, adaptability to ground deformation, and auxiliary waterproofing. Traditional rectangular jacking pipe longitudinal joints often employ a "single bolt connection" or "simple tenon joint" structure, which suffers from insufficient shear resistance, low bending moment transfer efficiency, and inability to adapt to minor ground deformations. Figure 11As shown, this invention utilizes a composite structural form combining an "F-type socket joint, a tenon-and-groove shear structure, and a (10.9 grade) high-strength bolt bending structure" to create a multi-dimensional force transmission and deformation adaptation system, significantly improving the overall performance of the longitudinal joint. The F-type socket joint consists of a tenon and a groove at the end of each pipe section. The length of the tenon and the depth of the groove are both controlled between 150mm and 200mm. The core function of this structure is to achieve rapid positioning during pipe section assembly, ensuring precise docking of adjacent sections. Simultaneously, its socket joint design can adapt to the small rotation angles (≤0.5°) of the pipe section caused by ground deformation under ultra-deep burial conditions, avoiding excessive joint opening (>6mm) caused by excessive rotation angles in traditional flat-mouth joints. Furthermore, the contact surface of the F-type socket joint can adopt a stepped design to extend the infiltration path of groundwater, providing auxiliary protection for subsequent waterproofing structures. The tongue-and-groove shear-resistant structure is set on the inner and outer sides of the F-type socket structure. The tenon height is controlled at 70mm~80mm, and the mortise depth is 5mm greater than the tenon height, leaving a 5mm gap for injecting modified epoxy grout after the pipe section is assembled. This tongue-and-groove structure breaks through the traditional joint's single mode of relying solely on bolts for shear resistance. It directly transmits longitudinal shear force through the mechanical interlocking of the tenon and mortise. Mechanical calculations have verified that the shear bearing capacity of a single set of tongue-and-groove tenons can reach 300kN~400kN. Combined with multiple sets of tongue-and-groove tenons between adjacent sections (8~10 sets per ring longitudinal joint), it can effectively bear most of the longitudinal shear force of the pipe section (e.g., the longitudinal shear force design value of 600kN for the No. 18 line jacking pipe), avoiding shear failure of bolts due to excessive shear force alone. Meanwhile, the reserved 5mm gap, after being filled with modified epoxy grout, can eliminate installation errors and gaps between the tenon and mortise, avoid local stress concentration during the stress process, further improve the crack resistance of the joint, and the high bonding strength of the modified epoxy grout can help enhance the overall integrity of the joint. The (10.9 grade) high-strength bolt bending structure is evenly arranged along the longitudinal joint. The bolt specification can be M30, and the bolt length can be determined according to the pipe section thickness (e.g., when the pipe section thickness is 800mm, the bolt length is 180mm). 2-3 sets of bolts are set per linear meter of longitudinal joint, and the bolt preload is controlled at about 260kN. The preload makes the adjacent sections fit tightly together, forming an overall stress system to transfer the longitudinal bending moment. The bolt selection is tailored to the high bending moment requirements of ultra-deep buried conditions. A grade 10.9 high-strength bolt with a yield strength ≥1080MPa and tensile strength ≥1200MPa is chosen. Its load-bearing capacity is increased by approximately 70% compared to traditional grade 8.8 bolts (yield strength ≥640MPa), effectively transferring negative bending moments at pipe corners (such as the bending moment of -1841kN·m at the corner of the No. 15 jacking pipe), preventing bolt breakage due to insufficient strength. Simultaneously, a waterproof sealing gasket is installed at the bolt head to prevent groundwater from seeping into the pipe through the bolt hole, achieving a dual function of load-bearing and waterproofing.

[0038] Furthermore, the structural design of the circumferential joint can then be implemented. The circumferential joint is used to realize shear force transfer, deformation coordination, and sealing protection between adjacent pipe sections. Traditional circumferential joints mostly adopt "tip-and-groove" or "flat-mouth" structures, which have problems such as uneven shear force transfer, poor sealing performance, and weak adaptability to differential settlement of strata. Figure 12 As shown, this invention constructs a circumferential joint system with reliable shear force transmission, strong deformation adaptability, and excellent waterproof performance through a composite form of "CT bolt connection combined with tenon structure" and a reserved gap grouting process. The CT bolt connection uses a ring-shaped connector as the core load-bearing component. The material of the CT bolt is the same as that of the high-strength bolts in the longitudinal joint (grade 10.9 high-strength steel), with a bolt diameter of 30mm. Each ring-shaped joint has 8-12 sets of CT bolts, and the bolt preload is controlled at approximately 260kN. The ring structure of this CT bolt can achieve 360° uniform force distribution. Compared with traditional single straight bolts, its shear resistance is improved by about 30%, and it can simultaneously transmit radial shear force and axial tensile force. Three-dimensional mechanical simulation verification shows that the total shear bearing capacity of each ring of CT bolts can reach 1032kN, fully meeting the shear force transmission requirements between rings under ultra-deep burial conditions (such as the design control value of 1032kN for the shear force between rings in the No. 18 line jacking pipe). Furthermore, the mounting holes for the CT bolts are positioned using pre-embedded steel sleeves to ensure bolt installation accuracy and prevent uneven stress due to installation deviations. The tenon structure and the mortise-and-tenon structure of the longitudinal joint are designed in tandem, with the tenon height and mortise depth consistent with the longitudinal joint (tenon height 70mm~80mm, mortise depth 75mm~85mm), and a 5mm gap is reserved for injecting modified epoxy grout. This tenon structure restricts the radial displacement and rotation of adjacent pipe rings, preventing excessive misalignment between pipe rings due to differential settlement in the strata (design control for misalignment ≤1mm). Simultaneously, its mechanical interlocking effect assists the CT bolts in transferring some of the inter-ring shear force, further optimizing the stress distribution of the joint. The modified epoxy grout filling process with the reserved gap allows the tenon structure to form an integral stress interface, eliminating stress concentration caused by the gap between the tenon and mortise. At the same time, the strong bond between the grouting material and the pipe section concrete enhances the integrity and waterproof performance of the circumferential joint. In addition, the circumferential joint is also equipped with a DN30 grouting hole and an exhaust pipe. The grouting hole is used for the application of modified epoxy grout, and the exhaust pipe is used to remove air during the grouting process to ensure the compactness of the grout and avoid the joint from becoming weak or failing to waterproof due to residual air bubbles.

[0039] Taking the Hangzhou Metro Line 18 pipe jacking project as an example, the detailed design parameters of its pipe section structure system are as follows: The pipe section adopts a two-piece segmentation scheme, with the segmentation position set in the middle of the side wall. The weight of a single pipe section is 48.5t, which is suitable for on-site hoisting equipment; the longitudinal joint adopts the design of "F-type socket structure, mortise and tenon joint (tenon height 75mm) combined with 10.9 grade M30 high-strength bolts (bolt preload controlled at about 260kN)", with 8 sets of high-strength bolts set in each ring, leaving a 5mm gap for injection of modified epoxy grout; the circumferential joint adopts "8 sets of CT bolts (preload 355kN) combined with tenon structure (tenon height 75mm)". The design includes a 5mm gap for grouting. ANSYS mechanical simulation verified that under an 11m overburden pressure, the structural system exhibits a top bending moment of 1910kN·m and a corner bending moment of -1498kN·m, with a longitudinal joint shear force transmission efficiency exceeding 95% and a circumferential joint misalignment ≤0.8mm, fully meeting design requirements. The Hangzhou Metro Line 15 pipe jacking project utilizes the same structural system. Under a specific geological condition with a 22m overburden pressure, this system exhibits a top bending moment of 2516kN·m and a corner bending moment of -1841kN·m, with stable inter-ring shear force transmission, further demonstrating the effectiveness and adaptability of the pipe section structural system design.

[0040] Preferably, step S4 can construct a closed-loop waterproofing system by screening the core materials of the main structure, joint stress and sealing waterproofing, and combining the material characteristics, so as to solve the problems of material and working conditions being disconnected and waterproofing failing in traditional engineering, and adapt to ultra-deep burial, high water pressure and soft strata conditions.

[0041] Preferably, in terms of material selection for pipe section components, the core materials and performance indicators can be determined based on the preceding structural system (segmentation, joint construction) and stress characteristics (top and bottom bending moments, inter-ring shear force). For example, the main structure can use C50 high-performance concrete, and the impermeability grade can be dynamically set according to the confined water head (P10 for water head ≤25m, P12 for >25m) to meet the top and bottom bending moments (e.g., the top bending moment of Line 15 is 2516kN·m) and impermeability requirements. The reinforcing steel is selected from HRB400E grade, and Φ22~25mm steel is used in high stress areas (top and corners) and Φ16~18mm steel is used in low stress areas according to "differentiated reinforcement". In the joint load-bearing materials, both longitudinal and circumferential bolts are 10.9 grade high-strength bolts (M30 specification), which are suitable for the shear force between rings (design control value 1032kN) and the transfer of bending moment at the joint. The pre-embedded steel sleeve is made of Q355 grade steel. The sealing and waterproofing materials include waterproof gaskets and wedge-shaped rubber rings. The waterproof gaskets may further include EPDM rubber gaskets (ultimate water pressure resistance ≥2.0MPa) and water-swellable rubber sheets. The wedge-shaped rubber rings may be made of neoprene rubber. Modified epoxy grout is used for gap grouting to ensure sealing and filling effects.

[0042] Preferably, such as Figure 13 As shown, the grouting holes are categorized by function and can all be made of Q235 steel to avoid damage to the hole walls during grouting. Specifically, drag-reducing grouting holes can use DN25mm steel pipes for injecting thixotropic mud to reduce drag; filling grouting holes and tenon / groove grouting holes (longitudinal and circumferential joints) can use φ15mm steel pipes for injecting modified epoxy grout to fill the joints and tenon / groove gaps; replacement grouting holes can use DN50mm steel pipes with tension joints for replacing grout behind the wall and reinforcing the stratum; φ15mm vent holes can also be used to expel grouting air and prevent air bubble residue. The grouting holes are arranged according to the principle of "uniform circumferential distribution," with 8-12 groups per ring to accommodate multiple waterproofing and drag-reduction requirements. The hoisting holes can be made of Q235 or Q355 steel pre-embedded sleeves with an inner diameter that matches the hoisting bolts. The hole positions should avoid high stress areas such as the top and corners of the pipe section, and be selected in the middle of the side wall near the center of gravity. Two sets can be set for each pipe section. After hoisting, C50 micro-expansion concrete can be used to seal the holes to prevent water seepage.

[0043] Furthermore, such as Figure 11 and Figure 14 As shown, based on the above materials, a multi-layered waterproofing system can be constructed: the first layer is structural self-waterproofing, relying on the density of C50 concrete (P10 / P12) to block groundwater infiltration; the second layer is the main joint seal, composed of a waterproof sealing gasket (of which, the EPDM rubber sealing gasket has a pre-set groove and a compression rate ≥20%) and a wedge-shaped rubber ring made of neoprene rubber, forming a water-facing surface protection; the third layer is gap grouting waterproofing, which fills the 5mm reserved gap of the joint tenon and mortise with modified epoxy grout to eliminate voids and enhance the overall integrity; the fourth layer is emergency waterproofing, with grouting holes reserved on the inner side and configured with quick-setting dual-liquid grout to deal with sudden leakage.

[0044] Taking Hangzhou Metro Lines 18 and 15 as examples: Line 18 uses C50 (P10) concrete, 10.9 grade M30 bolts, and waterproof sealing gaskets including EPDM rubber gaskets, achieving zero leakage at a water head of 32m; Line 15 uses C50 (P12) concrete, achieving waterproofing at a water head of 30m, verifying the effectiveness of the solution. Grouting holes are made of Q235 steel, with drag-reducing holes of DN25mm and tenon holes of φ15mm; lifting holes use Q355 steel sleeves, ensuring no leakage after sealing, meeting the requirements for ultra-deep burial conditions.

[0045] Example 2 This embodiment is a further improvement on embodiment 1, and repeated content will not be described again.

[0046] This invention discloses an ultra-deep buried large-section rectangular jacking pipe, which can be designed using the design method described in Example 1 to determine the design parameters.

[0047] This invention also discloses a construction method for ultra-deep buried large-section rectangular pipe jacking as described above, which may include one or more of the following steps: S101. Based on geological and hydrological characteristics (such as ultra-deep burial and high water pressure) and surrounding environmental constraints, a water-stop curtain combined with high-pressure reinforcement technology is used to treat the end soil. The groundwater level is controlled below the design safety threshold by the simultaneous construction of a dewatering system, which is suitable for construction needs in high-risk strata. S102. Based on the optimized cross-sectional parameters (such as side wall height, transition arc radius, etc.), calibrate the excavation dimensions of the pipe jacking machine and the starting bracket benchmark, raise the bracket according to the pre-set slope to prevent posture deviation, and adapt to the cross-sectional stress and construction safety design requirements. S103. Hoist the pipe sections according to the design block scheme. When connecting, prioritize positioning through the F-type socket structure, and then tighten the high-strength bolts to complete the longitudinal / circumferential composite joint assembly. Leave the joint gap for filling grout to ensure the implementation of the block collaborative force design. S104. Control the single ring jacking length according to the designed ring width. Parallel assembly is adopted for straight sections. The gap between rings is adjusted according to the designed wedge amount for curved sections. During tunneling, the excavation face pressure is dynamically adjusted based on deformation control targets (such as deflection and settlement) to adapt to the cross-section line and structural safety design. S105. A multi-layered waterproofing system is designed around the pipe section. Before the pipe section is assembled, sealing components are laid. After assembly, modified epoxy grout is injected through the filling grouting holes and the tenon groove grouting holes to form a closed-loop protection that combines structural self-waterproofing, joint sealing and gap grouting, which is suitable for high water pressure waterproofing design. S106. When crossing sensitive areas (such as buildings and pipelines), increase the monitoring intensity according to the design deformation control threshold, and adjust the controllable parameters (such as advancing speed and grouting volume) simultaneously to strengthen the grouting behind the wall to compensate for the stratum deformation and adapt to the surrounding environmental protection design constraints. S107. During the receiving phase, install the receiving base and anti-collision device according to the design alignment. After calibrating the position of the tunnel portal, advance the pipe jacking machine with low disturbance, complete the tunnel portal sealing and equipment separation, and ensure that the pipe section axis meets the design requirements. S108. After the jacking is completed, carry out grout replacement behind the wall, caulking of pipe joints and sealing of reserved holes, and complete the subsequent reinforcement and waterproofing finishing, so as to achieve the goals of long-term structural stability and waterproofing reliability in the design method.

[0048] Furthermore, the following is an example of the construction process for ultra-deep buried large-section rectangular pipe jacking: Based on the geological and hydrological characteristics of design method S1 (ultra-deep buried soil ≥10m, high water pressure ≥20m), the end TRD water-stop curtain combined with RJP high-pressure jet grouting pile reinforcement was carried out, and the pressure reduction well was constructed simultaneously to lower the water level to 1m below the tunnel bottom, which is suitable for high water pressure risk prevention and control design. Based on the optimal cross-sectional parameters determined by design method S2 (such as 3.0m for the side wall of Line 18 and 1.5m for the transition arc), the excavation dimensions of the pipe jacking machine (12020mm×8720mm) are calibrated. When installing the starting bracket, it is raised by 10~20mm according to the design cross-sectional slope to prevent the head from falling, and to adapt to the cross-sectional optimization results. For the two-piece segmented scheme (middle joint of side wall) of design method S3, a special lifting tool is used to lift a single 48.5t pipe section, and the segments are connected according to the design position. The tongue and groove of the F-type socket longitudinal joint are installed simultaneously, and a 5mm gap is reserved for injection of modified epoxy grout. Following the design method S3 for the composite joint construction, during assembly, the longitudinal joint is first positioned by the F-type socket, and then the 10.9 grade M30 high-strength bolts are tightened according to the design torque. The circumferential joint is equipped with 10~12 sets of CT bolts (preload 355kN) to ensure that the joint stress is adapted to the design requirements. Before the tunnel portal is removed, the engineering constraints of design method S1 (avoiding the cultural relic body) are checked, and the position of the tunnel portal in the curved section (R=8335m of Line 18) is verified. After removal, the extension guide rail anti-collision head is installed to adapt to the planar alignment design. During normal tunneling, the excavation face is controlled based on the deformation control target (deflection ≤ 1 / 400L) of design method S2 and the earth pressure value (0.1~0.18MPa for line 18) calibrated by ANSYS simulation. Simultaneously, the jacking length of each ring is controlled according to the design ring width of 1.5m. The inter-ring assembly gap is adjusted according to the wedge amount of 3mm in the curved section. For the multi-layer waterproofing system of design method S4, waterproof sealing gaskets (compression rate ≥20%) are pasted before the pipe sections are lowered into the well. After assembly, modified epoxy grout is injected through φ15mm tenon groove grouting holes to fill the joint gaps, which is suitable for high water pressure waterproofing design. When passing through buildings (such as Kaijing Apartment on Line 18), the settlement and tilt of the buildings are monitored more frequently according to the deformation threshold (differential settlement ≤ 5mm) of design method S1. The advancing speed is adjusted to 10mm / min. At the same time, thixotropic mud is added through DN25mm drag-reducing grouting holes to control the disturbance to the pile foundations and foundations of adjacent buildings, so as to adapt to the design constraints of the protection of existing structures in sensitive areas. During the receiving phase, in accordance with the wedge requirements of design method S2, the straight section (line 15) is assembled and connected in parallel, and the curved section is calibrated with a 3mm wedge to ensure that the misalignment between rings is ≤1mm and matches the cross-sectional profile design. After the jacking is completed, in accordance with the emergency waterproofing requirements of design method S4, a two-component grout is injected through the reserved grouting hole to replace the thixotropic mud. The joints of the pipe sections are sealed with polysulfide sealant, and the lifting holes (C50 micro-expansion concrete) are plugged to complete the closed loop of the waterproofing system.

[0049] It should be noted that the specific embodiments described above are exemplary. Those skilled in the art can devise various solutions inspired by the disclosure of this invention, and these solutions all fall within the scope of this invention and its protection. Those skilled in the art should understand that this specification and its accompanying drawings are illustrative and not intended to limit the scope of the claims. The scope of protection of this invention is defined by the claims and their equivalents. This specification contains multiple inventive concepts; terms such as "preferredly," "according to a preferred embodiment," or "optionally" indicate that the corresponding paragraph discloses an independent concept. The applicant reserves the right to file divisional applications based on each inventive concept.

Claims

1. A design method for ultra-deep buried large-section rectangular jacking pipe, characterized in that, It includes: S1. Clarify the geological and hydrological characteristics and engineering constraints under conditions of ultra-deep burial, high water pressure, and weak strata; S2. By dynamically defining core parameters including sidewall height, radius of the inner arc surface of the transition arc and / or radius of the inner arc surface of the arch crown, a multi-objective optimization model is constructed. The parameter combination enumeration method and three-dimensional mechanical simulation are used to screen the globally optimal section parameters and determine the ring width and wedge amount to form a complete section parameter system. S3. Based on the cross-sectional parameters and working conditions, plan the pipe section segmentation scheme, design the composite structure of longitudinal joints and circumferential joints, and reserve gaps for injection of modified epoxy grout. S4. Select core materials, classify and set grouting holes and hoisting holes, and build a multi-layer waterproof system based on core materials to adapt to ultra-deep buried high water pressure conditions.

2. The design method according to claim 1, characterized in that, In step S2, the optimization objectives of the multi-objective optimization model include structural safety, economic efficiency, stress balance, and construction adaptation. The structural safety objective is to ensure that the maximum deflection of the pipe section structure under ultra-deep burial conditions does not exceed the preset deformation threshold. The economic objective is to control the excavation area of ​​the pipe jacking to not exceed the preset area threshold. The stress balance objective is to ensure that the bending moment values ​​at the top, bottom, and corners of the pipe section are less than the threshold and are evenly distributed. The construction adaptation objective is to ensure that the weight and size of the pipe section corresponding to the optimized cross-sectional parameters match the carrying capacity of the transportation path and the tonnage of the hoisting equipment.

3. The design method according to claim 1 or 2, characterized in that, In step S2, the optimization solution and verification are performed by using three-dimensional mechanical simulation software to perform standardized performance verification on feasible cross-section combinations. Then, the final optimal cross-section parameters are determined by using a method of local extreme value screening combined with global optimal verification. The standardized performance verification is based on typical load combinations under ultra-deep burial conditions.

4. The design method according to any one of claims 1 to 3, characterized in that, In step S2, the ring width and wedge shape are determined by combining the prefabrication and transportation capacity of the pipe section, the bearing capacity of the hoisting equipment, and the planar alignment characteristics of the jacking section. The ring width and wedge shape, together with the sidewall height, the inner arc radius of the transition arc, and the inner arc radius of the arch crown, constitute a complete cross-sectional parameter optimization framework.

5. The design method according to any one of claims 1 to 4, characterized in that, In step S3, the composite structure of the longitudinal joint includes an F-type socket structure, a tongue and groove anti-shear structure, and a high-strength bolt anti-bending structure. The F-type socket structure is formed by the tenon and groove at the end of the pipe section. The tongue and groove anti-shear structure is set on the inner and outer sides of the F-type socket structure. The high-strength bolt anti-bending structure is evenly arranged along the longitudinal joint.

6. The design method according to any one of claims 1 to 5, characterized in that, In step S3, the composite structure of the circumferential joint includes a CT bolt connection and a tenon structure. The CT bolt connection uses a ring connector as the core load-bearing component, and the tenon structure is designed in conjunction with the tongue and groove tenon structure of the longitudinal joint.

7. The design method according to any one of claims 1 to 6, characterized in that, In step S4, the core materials selected include main structural materials, joint load-bearing materials, and sealing and waterproofing materials. The main structural material is high-performance concrete, the joint load-bearing materials include high-strength bolts and pre-embedded steel sleeves, and the sealing and waterproofing materials include waterproof sealing gaskets and wedge-shaped rubber rings.

8. The design method according to any one of claims 1 to 7, characterized in that, In step S4, the multi-layer waterproofing system includes structural self-waterproofing, joint main sealing, gap grouting waterproofing, and emergency waterproofing. The structural self-waterproofing relies on the density of the main structural material. The joint main sealing uses the sealing waterproofing material. The gap grouting waterproofing fills the joints and the gaps between the tongue and groove with modified epoxy grout. The emergency waterproofing is achieved by configuring a quick-setting dual-liquid grout through the reserved grouting holes on the inside.

9. A type of ultra-deep buried large-section rectangular jacking pipe, characterized in that, It employs the design method described in any one of claims 1 to 8 to determine the design parameters.

10. A construction method for ultra-deep buried large-section rectangular pipe jacking as described in claim 9, characterized in that, It includes one or more of the following steps: Based on geological and hydrological characteristics and surrounding environmental constraints, a water-stop curtain combined with high-pressure reinforcement technology was used to treat the end soil, and a dewatering system was constructed simultaneously to control the groundwater level below the design safety threshold, which is suitable for construction needs in high-risk strata. Based on the optimized cross-sectional parameters, the excavation dimensions of the pipe jacking machine and the reference of the starting bracket are calibrated. The bracket is raised according to the pre-set slope to prevent posture deviation and to adapt to the cross-sectional stress and construction safety design requirements. According to the design block plan, the pipe sections are hoisted and positioned first through the F-type socket structure during docking, and then the longitudinal / circumferential composite joint is assembled by tightening high-strength bolts. The joint gap is reserved for filling grout to ensure that the block collaborative stress design is implemented. The single-ring jacking length is controlled according to the designed ring width. Parallel assembly is adopted for straight sections, and the inter-ring gap is adjusted according to the designed wedge amount for curved sections. During tunneling, the excavation face pressure is dynamically adjusted based on the deformation control target to adapt to the cross-section line and structural safety design. The design incorporates a multi-layered waterproofing system. Before the pipe sections are assembled, sealing components are laid. After assembly, modified epoxy grout is injected through filling grouting holes and tenon grouting holes to form a closed-loop protection system that combines structural self-waterproofing, joint sealing, and gap grouting, making it suitable for high water pressure waterproofing designs. When crossing sensitive areas, monitoring is intensified according to the design deformation control threshold, controllable parameters are adjusted synchronously, and grouting behind the wall is strengthened to compensate for stratum deformation and adapt to the surrounding environmental protection design constraints. During the receiving phase, the receiving base and anti-collision device are installed according to the design alignment. After calibrating the position of the tunnel portal, the pipe jacking machine is advanced with low disturbance. The tunnel portal is sealed and the equipment is separated to ensure that the pipe section axis meets the design requirements. After the jacking is completed, the wall grout replacement, joint caulking of pipe sections and sealing of reserved holes are carried out to complete the subsequent reinforcement and waterproofing finishing, so as to achieve the goals of long-term structural stability and waterproofing reliability in the design method.

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