Bridge abutment pile foundation isolation protection structure near pipeline and construction method

Abstract

The application discloses a kind of abutment pile foundation isolation protection structures and construction methods close to pipeline, belong to foundation engineering foundation pit pipeline protection technical field.Protection structure includes upper suspender, pipeline sheath and multiple vertical suspender, upper suspender is anchored in the soil body of both sides of foundation pit at both ends, pipeline sheath is covered with C-shaped steel buckling structure to underground communication optical cable and is locked by fixing piece, vertical suspender connects upper suspender and pipeline sheath to form suspension system, and the spacing calculation formula of fixing piece and linkage monitoring unit are given.The construction method includes pipeline positioning, layered excavation, sheath installation, suspension assembly, monitoring backfilling and site recovery process, and uses side pressure synchronous balance layered backfilling process to dynamically offset additional bending moment.The application can quantitatively match the mechanical properties of foundation pit construction, effectively resist construction dynamic load and soil side pressure, realize whole-process stress controllable, and ensure the safety of pipeline operation during abutment foundation construction.

Description

Technical Field

[0001] This invention relates to the field of protection technology for underground pipelines in foundation pit construction, specifically to a suspension protection structure and construction method for pipelines in bridge abutment foundation construction near underground gas pipelines. Background Technology

[0002] In bridge abutment foundation construction, typical foundation work includes excavation, slope protection, and layered backfilling. When the construction area is near existing underground gas pipelines and corresponding optical fiber cables, the soil unloading and rebound caused by excavation, lateral slope displacement, and the consolidation settlement and lateral earth pressure of the backfill soil will cause additional deformation and stress to the underground pipelines. As a supporting facility for monitoring and controlling the transmission of signals for the gas pipeline operation, excessive deformation of the optical fiber cable will directly affect the safe management of the gas transmission system. Therefore, reliable protection of nearby underground pipelines throughout the entire foundation construction process is a core technical issue in ensuring the safety of existing underground facilities in the field of foundation engineering. Currently, conventional protection methods in this field mainly fall into two categories: one is to install a rigid protective cover on the outside of the pipeline to resist the squeezing of backfill soil and the collision load of construction machinery; the other is to use simple suspension rods to suspend the pipeline and offset the vertical deformation caused by soil settlement.

[0003] The existing protection schemes mentioned above have significant shortcomings in practical applications of bridge abutment foundation construction. The design parameters of the protection structure are not matched with the mechanical properties of the excavation pit. The spacing of the shell fixing components and the spacing of the hangers are mostly determined by engineering experience, without quantitative calculation of the bending stress of pipelines under the coupling effect of the pit unloading effect and construction dynamic load. This easily leads to excessive bending deformation of the shell and makes it difficult to adapt to foundation construction scenarios with different excavation depths and different soil conditions.

[0004] Therefore, there is an urgent need for a pipeline suspension protection structure and construction method for bridge abutment foundation construction that is compatible with the entire process of bridge abutment foundation excavation and backfilling, has quantitative mechanical design basis, and can dynamically adjust to offset the effects of soil lateral pressure and settlement on adjacent underground gas pipelines. Summary of the Invention

[0005] This invention aims to address the problems of insufficient reliability of underground communication optical cable protection and lack of quantitative design and dynamic control capabilities in the existing technology during bridge abutment foundation construction. It provides a pipeline suspension protection structure and construction method for bridge abutment foundation construction near underground gas pipelines. Through the quantitative design of the suspension protection system and the dynamic control of the backfilling process, pipeline safety protection can be achieved throughout the entire foundation construction cycle.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] On one hand, a suspended protection structure for underground communication optical cables is provided for bridge abutment foundation construction near underground gas pipelines. This structure, located outside the foundation construction pit, includes an upper suspension rod, a pipeline sheath, and multiple vertical suspension rods. The upper suspension rod is arranged axially parallel to the underground communication optical cable, with both ends anchored to the slope soil on both sides of the foundation construction pit. The pipeline sheath includes a C-shaped sheath and multiple sets of fixing components. The C-shaped sheath covers the outside of the underground communication optical cable, with both ends extending and anchored to the slope soil on both sides of the foundation construction pit. The multiple sets of fixing components are spaced apart axially along the underground communication optical cable, locking and securing the joints of the C-shaped sheath. Each vertical suspension rod is arranged radially spaced along the underground communication optical cable, with its upper end fixedly connected to the upper suspension rod and its lower end fixedly connected to the pipeline sheath.

[0008] Furthermore, the C-shaped sheath is formed by interlocking two C-shaped steels with opposite openings to create a closed protective cavity. The underground communication optical cable is housed within the closed protective cavity. A flexible buffer layer is filled between the inner wall of the C-shaped sheath and the outer wall of the underground communication optical cable. The flexible buffer layer is evenly wrapped around the outer wall of the underground communication optical cable. The opening end of the C-shaped steel is provided with a corner structure.

[0009] Furthermore, the maximum axial spacing L between two adjacent sets of the fasteners satisfies the following formula:

[0010] ;

[0011] In the formula: The section modulus of the C-shaped shell is given by [value missing]. ; The flexural modulus of the underground communication optical cable body is given in units of 1. ; The design value of the flexural strength of the C-type shell material, in units of ; The unit weight per unit length is the standard value of the combined self-weight of the pipeline sheath and the underground communication optical cable, in units of... ; The standard value of the equivalent uniformly distributed collision load for bridge abutment foundation construction is given, in units of... ; This is the dynamic load amplification factor for construction, with a value ranging from 1.3 to 1.8.

[0012] Furthermore, the fastener includes a C-clamp and a retaining plate, which are secured by fasteners.

[0013] Furthermore, both ends of the upper suspension rod and the pipeline casing are provided with inverted trapezoidal anchoring sections. After the inverted trapezoidal anchoring sections are buried in the slope soil, they are filled with cement. The vertical suspension rod is an adjustable length tie rod structure.

[0014] Furthermore, the embedment depth of the inverted trapezoidal anchoring section is at least 300 mm.

[0015] Furthermore, it also includes a monitoring unit, which includes a vibrating wire strain sensor installed on the outer wall of the underground gas pipeline, an optical cable stress sensor installed inside the pipeline casing, and a wireless acquisition and early warning terminal.

[0016] On the other hand, a construction method for the pipeline suspension protection structure for bridge abutment foundation construction as described above is also provided, including the following steps:

[0017] S1 pipeline exploration and positioning: Before the foundation construction pit is excavated, the plane position, burial depth and direction of the underground gas pipeline and the underground communication optical cable are determined.

[0018] S2 Foundation Pit Layered Excavation: Determine the slope coefficient according to the soil type, and excavate the foundation construction pit in layers. When the excavation reaches the elevation of the underground communication optical cable, manually remove the soil and expose the underground communication optical cable.

[0019] S3 Pipeline Sheath Installation: Clean the soil adhering to the outer wall of the underground communication optical cable, fasten the C-shaped sheath to cover the outside of the underground communication optical cable, install the fixing parts at intervals along the axial direction and lock them, adjust the axial position of the pipeline sheath so that its two ends are respectively anchored to the slope soil on both sides of the foundation construction pit.

[0020] S4 Suspension System Assembly: The upper suspension rod is installed at the top of the foundation construction pit along the axis parallel to the underground communication optical cable. The two ends of the upper suspension rod are anchored to the slope soil on both sides. Multiple vertical suspension rods are installed, and the upper end of the vertical suspension rod is fixedly connected to the upper suspension rod, and the lower end is fixedly connected to the pipeline casing.

[0021] S5 monitoring deployment: Install the monitoring unit and set the strain early warning threshold, construct the horizontal load isolation structure above the underground gas pipeline, and backfill the foundation construction pit in layers.

[0022] S6 Site Restoration: Construct longitudinal drainage ditches on both sides of the foundation construction pit to complete the construction.

[0023] Furthermore, in step S5, a lateral pressure synchronous balance layered backfilling process is adopted. The earthwork backfilling is carried out symmetrically and synchronously along both sides of the pipeline casing. The thickness of each backfilling layer is no more than 200mm. After each layer of backfilling is completed, the monitoring unit collects the soil lateral pressure data on both sides of the pipeline casing and synchronously fine-tunes the tension of the vertical hanger at the corresponding position to counteract the additional bending moment generated by the lateral pressure.

[0024] Furthermore, the final consolidation settlement is calculated based on the compression modulus of the backfill soil and the thickness of the cover soil, and the preset lifting amount of the pipeline casing is determined.

[0025] Compared with the prior art, the present invention has the following significant advantages:

[0026] 1. The suspension system, which combines the upper suspension rod and the pipeline casing, and the calculation formula for the spacing of the fixing parts based on the bending bearing capacity, can match the mechanical characteristics of the foundation pit construction to realize the quantitative design of protection parameters, effectively resist the dynamic load of construction and the lateral pressure of the soil, and ensure the safety of the optical cable under stress.

[0027] 2. The shell structure adopts C-shaped steel interlocking with flexible buffer, which has both rigid protection and buffer energy absorption effect. With adjustable length vertical hangers, it can be adapted to different settlement conditions, is easy to install, and is suitable for complex construction environment of bridge abutment foundation pit.

[0028] 3. The matching side pressure synchronous balance backfilling process and dual-parameter linkage monitoring system can dynamically offset the additional bending moment during backfilling, realize the controllability of pipeline stress throughout the foundation construction process, and significantly reduce the risk of pipeline damage during construction of nearby gas transmission pipelines. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structural layout of an embodiment of the present invention;

[0030] Figure 2 This is a schematic plan view of the overall structure of an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the upper suspension rod installation structure according to an embodiment of the present invention;

[0032] Figure 4 for Figure 3 A magnified view of part A in the image;

[0033] Figure 5 for Figure 3 A magnified view of part B in the image;

[0034] Figure 6 This is a schematic diagram of the flexible buffer pad structure according to an embodiment of the present invention;

[0035] Figure 7 This is a schematic diagram of a C-shaped steel structure according to an embodiment of the present invention;

[0036] Figure 8 This is a schematic diagram of the installation on the other side of the upper suspension rod according to an embodiment of the present invention;

[0037] Figure 9 for Figure 8 A magnified view of part C.

[0038] Among them, 1. Upper hanging rod; 11. Inverted trapezoidal anchoring section; 2. Pipeline casing; 21. C-shaped casing; 211. C-shaped steel; 212. Corner; 22. Fixing component; 221. C-shaped clamp; 222. Clamping plate; 223. Fastener; 23. Enclosed protective cavity; 24. Flexible buffer pad; 3. Vertical hanging rod; 4. Underground communication optical cable; 5. Foundation construction pit; 51. Slope soil. Detailed Implementation

[0039] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0040] The following is combined Figures 1 to 9 The following describes embodiments of the present invention.

[0041] According to an embodiment of the present invention, a suspended protection structure for pipelines during bridge abutment foundation construction near an underground gas pipeline is provided. The structure is installed outside the underground communication optical cable 4 within the foundation construction pit 5 and includes an upper suspension rod 1, a pipeline sheath 2, and multiple vertical suspension rods 3. The upper suspension rod 1 is installed along an axis parallel to the underground communication optical cable 4, and both ends of the upper suspension rod 1 are anchored within the slope soil 51 on both sides of the foundation construction pit 5. The pipeline sheath 2 includes a C-shaped sheath 21 and multiple sets of fixing members 22. The C-shaped sheath 21 covers the outside of the underground communication optical cable 4, and both ends of the pipeline sheath 2 extend and are anchored within the slope soil 51 on both sides of the foundation construction pit 5. The multiple sets of fixing members 22 are spaced apart along the axial direction of the underground communication optical cable 4 to lock and fix the joints of the C-shaped sheath 21. Each vertical hanger 3 is arranged radially at intervals along the underground communication optical cable 4. The upper end of the vertical hanger 3 is fixedly connected to the upper hanger 1, and the lower end of the vertical hanger 3 is fixedly connected to the pipeline casing 2.

[0042] The upper suspension rod 1 provides the top load-bearing support for the entire suspension protection system, transferring the self-weight of the pipeline casing 2 and the underground communication optical cable 4, as well as external loads, to the slope soil 51 on both sides of the foundation construction pit 5, ensuring the overall stability of the suspension structure. As the upper load-bearing component, the upper suspension rod 1 can be made of hot-rolled ordinary I-beams or round steel, possessing sufficient bending and shear bearing capacity, adaptable to foundation construction pit 5 operation scenarios of different spans, and directly erected within the soil slope 51 without affecting ground construction.

[0043] The pipeline casing 2 provides rigid protection for the underground communication optical cable 4, isolating it from external loads such as soil compression and machinery collisions during construction. Simultaneously, it serves as a load-bearing component for suspension, evenly transferring the load of the underground communication optical cable 4 to the vertical hanger 3. The pipeline casing 2 adopts a segmented prefabricated structure, allowing for rapid on-site assembly and installation without interrupting the operation of the underground communication optical cable 4. It is adaptable to foundation pit 5 sections of varying lengths.

[0044] The vertical hanger 3 is the force transmission component between the upper hanger 1 and the pipeline casing 2, realizing the vertical transmission of suspension force. Specifically, the vertical hanger 3 can be a round steel tie rod with a turnbuckle, and the length can be infinitely adjusted by rotating the turnbuckle. It is convenient to operate and has high adjustment accuracy, which can meet the dynamic fine adjustment needs during construction.

[0045] The underground communication optical cable 4 is the core protected object of this protective structure. It is usually laid in the same trench or adjacent to the underground gas pipeline. Damage to it during the excavation of the foundation pit 5 will directly affect the safety management of the underground gas pipeline. The foundation pit 5 is the excavation work space for the bridge abutment foundation construction. Its excavation process will disrupt the original soil stress balance and have a lateral unloading and settlement effect on the underground pipeline.

[0046] The slope soil 51 serves as the anchoring carrier at both ends of the suspension system, and the pull-out bearing capacity of the undisturbed soil ensures that the anchoring ends do not slip or pull out.

[0047] The C-type casing 21 is the main protective component of the pipeline casing 2. It is made of steel and has high cross-sectional rigidity, which can directly resist external impact and soil pressure. Its open structure makes it easy to fasten and install on site without the need for cable pulling operations, and does not affect the normal operation of the underground communication optical cable 4.

[0048] The fastener 22 is a locking component at the joint of the C-shaped shell 21. Its axial spacing ensures that the C-shaped shell 21 is tightly spliced, preventing the joint from opening and causing the protection to fail after being loaded. At the same time, it restrains the cross-sectional deformation of the C-shaped shell 21 and improves the overall bending resistance.

[0049] In some embodiments, the C-shaped sheath 21 is formed by two C-shaped steels 211 with opposite openings interlocking to form a closed protective cavity 23. The underground communication optical cable 4 is housed in the closed protective cavity 23. A flexible buffer layer 24 is filled between the inner wall of the C-shaped sheath 21 and the outer wall of the underground communication optical cable 4. The flexible buffer layer 24 is evenly wrapped around the outer wall of the underground communication optical cable 4. The end of the C-shaped steel 211 that abuts against the underground communication optical cable 4 is provided with a corner 212.

[0050] C-shaped steel 211 is the standard profile component of C-shaped shell 21. It is made of cold-formed thin-walled steel or ordinary channel steel. A single profile is easy to transport and place on site. Two profiles are interlocked to form a closed section, which greatly improves the bending modulus and torsional performance of the section.

[0051] The enclosed protective cavity 23 provides an independent protective space for the underground communication optical cable 4, isolating it from the intrusion of soil, water and construction debris, while buffering external impact loads and preventing the loads from acting directly on the surface of the underground communication optical cable 4.

[0052] The flexible buffer layer 24 is filled between the C-shaped sheath 21 and the underground communication optical cable 4. Specifically, it can be made of polyethylene foam board or rubber pad. On the one hand, it absorbs the kinetic energy of the collision and reduces the impact acceleration. On the other hand, it fills the gap to prevent the underground communication optical cable 4 from moving and wearing inside the C-shaped sheath 21. At the same time, it isolates the rigid sheath from the optical cable to prevent hard contact damage to the outer sheath of the underground communication optical cable 4.

[0053] The corner 212 is set at the open end of the C-shaped steel 211, changing the original sharp corner to a rounded transition or blunting of the corner, so as to prevent the sharp corner at the end of the C-shaped steel 211 from scratching the outer sheath of the underground communication optical cable 4 during installation or deformation under load, eliminating the risk of scratching rigid components and improving protection safety.

[0054] In some embodiments, the maximum axial distance L between two adjacent sets of fasteners 22 satisfies the following formula:

[0055]

[0056] This formula is derived based on the bending capacity theory of simply supported beams in mechanics of materials, combined with the load characteristics of foundation pit construction. The C-shaped sheath 21 and the underground optical cable 4 between adjacent fasteners 22 are simplified into a simply supported beam model bearing a uniformly distributed load. Using the design value of the bending strength of the C-shaped sheath 21 as a control condition, the maximum allowable span, i.e., the maximum axial spacing of the fasteners 22, is derived. The derivation process simultaneously considers the structural self-weight and construction collision loads, and introduces a dynamic load amplification factor to reflect the dynamic effect of construction impact. It also takes into account the bending contribution of the underground optical cable 4 itself, making the calculation results more consistent with the actual stress state of foundation pit construction and avoiding excessive bending deformation of the C-shaped sheath 21 and bending damage to the underground optical cable 4 due to excessively large spacing between the fasteners 22.

[0057] in, The flexural modulus of the C-shaped shell 21 is a core geometric parameter for measuring the bending capacity of the section. The larger the value, the greater the bending moment that can be withstood under the same strength, and the larger the allowable spacing of the fasteners 22. This parameter can be calculated using the section geometry formula based on the cross-sectional dimensions of the C-shaped steel 211.

[0058] The bending modulus of the cross section of the underground communication optical cable 4 is used. The optical cable itself has a certain bending stiffness and can share the bending moment with the C-shaped sheath 21. Taking this parameter into account can avoid conservative design and optimize the number of fasteners 22 while ensuring safety.

[0059] The design value of the bending strength of the C-type shell 21 material is determined by the grade and thickness of the steel used in the shell. It is a control index of the structural bending bearing capacity, ensuring that the C-type shell 21 does not undergo plastic yield failure under the most unfavorable load.

[0060] The total self-weight per unit length of the pipeline sheath 2 and the underground communication optical cable 4 is the standard value. It is the permanent uniformly distributed load borne by the structure and is obtained by the self-weight of the C-shaped sheath 21 profile, the self-weight of the flexible buffer pad 24, and the self-overlapping of the underground communication optical cable 4.

[0061] The standard value of the equivalent uniformly distributed collision load during bridge abutment foundation construction is the equivalent uniformly distributed value of accidental collisions such as equipment falling and soil collapse during construction, and is determined according to the construction conditions and equipment type.

[0062] This is the dynamic load amplification factor for construction, used to convert static collision loads into dynamic impact effects. The value ranges from 1.3 to 1.8, with a larger value for heavier construction equipment and higher operating height. The lower limit is used for conventional manual excavation and small equipment operation conditions, while the upper limit is used for large machinery operation conditions.

[0063] In the specific engineering design, considering the complex working conditions, dense heavy machinery, and high risk of soil falling and collision in the bridge abutment foundation construction area, C40×20×8×1.5 cold-formed thin-walled C-shaped steel 211 was selected to fabricate the C-shaped protective shell 21. The bending modulus of a single C-shaped steel 211 section is approximately 1.1 cm³, and the bending modulus of the combined section of two interlocking steel sections is... Take 2.2 cm³, convert to The bending modulus of the cross-section of a typical stranded underground communication optical cable. Pick The casing is made of Q235 grade galvanized steel strip, with a design bending strength of [value missing]. Take 205 MPa, that is The standard value of the total unit length self-weight of the pipeline casing 2 and the underground communication optical cable 4. Approximately 28 N / m. Standard value of equivalent uniformly distributed collision load during bridge abutment foundation construction. A dynamic load amplification factor of 42000 N / m is used to fully account for the impact effects of machinery collisions and soil collapses within the foundation pit. Take 1.6.

[0064] Substituting into the formula, the maximum axial spacing between two adjacent sets of fasteners 22 is approximately 0.495m. In engineering applications, 500mm is taken as the design spacing, which not only meets the bending bearing capacity requirements but also reserves sufficient safety margin, adapting to the complex working environment of bridge abutment foundation construction.

[0065] In some embodiments, the fastener 22 includes a C-clamp 221 and a clamping plate 222, which are fixed by fasteners 223.

[0066] C-clamp 221 is the main clamping component of the fastener 22. It is made of bent steel plate that matches the outer contour of C-shaped shell 21. It can wrap around and fasten the two C-shaped steels 211 from the outside, providing radial clamping force.

[0067] The clamping plate 222 is a locking pad on the opening side of the C-type clamp 221. It works with the C-type clamp 221 to form a closed hoop, so that the clamping force is evenly transmitted to both sides of the joint of the C-type protective shell 21.

[0068] The fastener 223 can be a high-strength bolt and nut assembly. By tightening the bolt, the C-type clamp 221 and the card plate 222 are locked together. The installation and disassembly are convenient, the tightening force is controllable, and the joint of the C-type protective shell 21 can be tightly fitted.

[0069] In some embodiments, both ends of the upper hanger 1 and the pipeline casing 2 are provided with inverted trapezoidal anchoring sections 11. After the inverted trapezoidal anchoring sections 11 are buried in the slope soil 51, they are filled with cement. The vertical hanger 3 is a tie rod structure with adjustable length.

[0070] The inverted trapezoidal anchorage section 11 is an end-pull-out resistance structure with an inverted trapezoidal cross-section. The insertion hole is sealed with cement. After insertion into the slope soil 51, it increases the contact area with the soil, enhancing the pull-out bearing capacity and preventing the anchorage end from being pulled out under suspended tension. The inverted trapezoidal wide-head structure utilizes the weight of the upper soil to provide pull-out resistance, offering higher reliability compared to direct-buried anchorages.

[0071] The cement filling can ensure that the soil around the inverted trapezoidal anchoring section 11 is compact, so that the inverted trapezoidal anchoring section 11 is tightly bonded to the soil, giving full play to the tensile strength of the soil, and avoiding the loose soil around the anchoring section that would lead to insufficient tensile strength.

[0072] The adjustable length tie rod structure allows the vertical hanger 3 to adjust the tension and elevation of the pipeline casing 2 according to the construction progress and settlement monitoring data, adapting to soil settlement deformation and avoiding excessive additional tension or sag of the underground communication optical cable 4 due to settlement.

[0073] In some embodiments, the inverted trapezoidal anchoring section 11 is embedded at a depth of at least 300 mm.

[0074] A minimum embedment depth of 300mm ensures that the inverted trapezoidal anchoring section 11 penetrates sufficiently into the slope soil 51, avoiding the loose surface soil and achieving stable pull-out bearing capacity. If the embedment depth is too shallow, the inverted trapezoidal anchoring section 11 will be located in the disturbed surface soil, resulting in insufficient pull-out force and easy pull-out failure; if the embedment depth is too large, it will increase the amount of excavation and increase construction costs.

[0075] In some embodiments, the system further includes a monitoring unit, which includes a vibrating wire strain sensor installed on the outer wall of the underground gas pipeline, an optical cable stress sensor installed inside the pipeline casing 2, and a wireless acquisition and early warning terminal.

[0076] Vibrating wire strain sensors are used to monitor the strain of underground gas pipeline walls in real time, understand the stress changes of underground gas pipelines during construction, detect the risk of pipeline deformation exceeding the standard in a timely manner, and ensure the safe operation of high-pressure gas pipelines.

[0077] The optical cable stress sensor is used to monitor the axial stress of the underground communication optical cable 4 and the stress state inside the pipeline sheath 2, directly reflecting the working effect of the protective structure and providing data basis for the tension adjustment of the vertical hanger 3.

[0078] The wireless acquisition and early warning terminal is responsible for collecting monitoring data from two types of sensors, performing real-time analysis and threshold judgment, and automatically issuing an early warning signal when the stress exceeds the preset early warning value, thereby realizing dynamic monitoring and risk warning throughout the construction process.

[0079] According to an embodiment of the present invention, a construction method for the above-mentioned bridge abutment foundation construction pipeline suspension protection structure is also provided, comprising the following steps:

[0080] S1 Pipeline Exploration and Location: Before excavating foundation pit 5, the planar location, burial depth, and direction of the underground gas pipeline and underground communication optical cable 4 are determined. By using geophysical instruments in combination with manual exploratory pits, the location parameters of the underground gas pipeline and underground communication optical cable 4 are accurately determined, avoiding blind excavation that could damage the pipelines, and providing a precise positioning basis for the subsequent layout of protective structures.

[0081] S2 Foundation Pit Layered Excavation: The slope coefficient is determined according to the soil type. The foundation construction pit 5 is excavated in layers. When the excavation reaches the elevation near the underground communication optical cable 4, manual cleaning is used to expose the underground communication optical cable 4. The layered excavation of the foundation pit follows the principle of top-down and layered unloading in foundation engineering construction. When mechanical excavation reaches the elevation near the underground communication optical cable 4, manual cleaning is used. This allows for precise control of the excavation depth and avoids accidental contact with the underground communication optical cable 4 by mechanical excavation. At the same time, the layered slope ensures the stability of the slope of the foundation construction pit 5 and prevents collapse.

[0082] S3 Pipeline Sheath Installation: Clean the soil adhering to the outer wall of the underground communication optical cable 4, fasten the C-shaped sheath 21 to cover the outside of the underground communication optical cable 4, install and lock the fixing pieces 22 at intervals along the axial direction, adjust the axial position of the pipeline sheath 2 so that both ends are anchored in the slope soil 51 on both sides of the foundation construction pit 5. First clean the surface of the underground communication optical cable 4 to ensure that the C-shaped sheath 21 fits tightly, and then fasten and lock it with the fixing pieces 22 to form a complete protective body. Anchor both ends into the slope soil 51 to achieve end fixation and provide a supporting foundation for subsequent suspension.

[0083] S4 Suspension System Assembly: An upper suspension rod 1 is installed at the top of the foundation pit 5, parallel to the axis of the underground communication optical cable 4. Both ends of the upper suspension rod 1 are anchored within the soil of the side slopes 51. Multiple vertical suspension rods 3 are then installed, with their upper ends fixedly connected to the upper suspension rod 1 and their lower ends fixedly connected to the pipeline casing 2. The upper suspension rod 1 is first fixed to form the top support point. Then, the pipeline casing 2 is connected via the vertical suspension rods 3, forming a complete suspension load-bearing system that transfers the load of the pipeline casing 2 and the underground communication optical cable 4 to the soil on both sides of the foundation pit 5.

[0084] S5 Monitoring Deployment: Install monitoring units and set strain early warning thresholds. Construct a horizontal load-bearing isolation structure above the underground gas pipeline, and backfill the foundation pit in layers. The monitoring deployment enables visualized risk management, pre-sets safety thresholds, and, in conjunction with the load-bearing isolation structure, further reduces the impact of construction loads on the underground gas pipeline. Layered backfilling controls the soil loading rate to avoid rapid loading that could lead to a sudden increase in pipeline deformation.

[0085] S6 Site Restoration: Construct longitudinal drainage ditches on both sides of foundation construction pit 5, and complete the construction. The site restoration will improve the drainage system to prevent surface water from seeping into the foundation construction pit 5, softening the soil and causing settlement, and ensuring the long-term stability of the site and pipelines after construction.

[0086] In some embodiments, step S5 adopts a lateral pressure synchronous balance layered backfilling process. The earthwork backfilling is carried out symmetrically and synchronously along both sides of the pipeline casing 2. The thickness of each backfilling layer is no more than 200mm. After each layer of backfilling is completed, the soil lateral pressure data on both sides of the pipeline casing 2 is collected by the monitoring unit, and the tension of the vertical hanger 3 at the corresponding position is adjusted synchronously to counteract the additional bending moment generated by the lateral pressure.

[0087] The lateral pressure synchronous balance layered backfilling process controls the soil pressure difference on both sides of the pipeline casing 2 through symmetrical backfilling, avoiding lateral bending of the pipeline casing 2 caused by lateral thrust generated by unilateral backfilling, which would then lead to torsion and bending of the underground communication optical cable 4. The 200mm thickness limit for each layer controls the amount of load applied at one time, facilitating stress monitoring and adjustment. After each layer of backfilling, the tension of the vertical hanger 3 is finely adjusted based on data from the monitoring unit, which can offset the additional bending moment generated by lateral pressure in real time, keeping the underground communication optical cable 4 in a state of axial tension at all times, avoiding damage to the optical cable from additional bending stress, and achieving dynamic stress balance during the backfilling process.

[0088] In some embodiments, the final consolidation settlement is calculated based on the compression modulus of the backfill soil and the thickness of the cover soil, and the preset lifting amount of the pipeline casing 2 is determined.

[0089] Backfill soil will undergo consolidation settlement under its own weight and the load from above. If the pipeline casing 2 is not pre-raised, the settlement will lead to an increase in the sag of the underground communication optical cable 4 and an increase in additional stress. By calculating the final settlement using soil mechanics consolidation theory, the pipeline casing 2 can be pre-raised by the corresponding value during installation. This ensures that the elevation of the underground communication optical cable 4 is consistent with the initial design elevation after settlement, avoiding the adverse stress caused by settlement and ensuring the long-term stability of the pipeline.

[0090] During actual construction, a pipeline detector combined with manual excavation is first used to determine the accurate location and burial depth of the underground gas pipeline and the underground communication optical cable 4, and the excavation boundary line of the foundation construction pit 5 is marked. The foundation construction pit 5 is excavated in layers according to the soil slope. When the distance from the underground communication optical cable 4 is 300mm above, mechanical operation is stopped, and manual cleaning with a flat-headed shovel is used to avoid damaging the outer sheath of the underground communication optical cable 4. After the underground communication optical cable 4 is fully exposed, the surface loose soil is cleaned, a flexible buffer layer 24 is wrapped around it, and two C-shaped steels 211 are interlocked from the top and bottom to cover the underground communication optical cable 4. C-shaped clamps 221 and clamping plates 222 are installed at the calculated intervals, and the fasteners 223 are tightened to lock it. The two ends of the pipeline sheath 2 are inserted into the soil 51 on both sides of the slope, and cement is backfilled and compacted to form an inverted trapezoidal anchoring section 11. A hanging rod 1 is erected at the top of the foundation pit 5, with inverted trapezoidal anchoring sections 11 at both ends. Vertical hanging rods 3 are installed at the designed intervals. The turnbuckles are adjusted to bring the pipeline casing 2 to the preset elevation, ensuring the underground communication optical cable 4 is in a straight and stressed state. Subsequently, vibrating wire strain sensors are attached to the outer wall of the underground gas pipeline, and optical cable stress sensors are installed inside the pipeline casing 2. Wireless acquisition and early warning terminals are connected, and early warning thresholds are set. Backfilling is carried out symmetrically along both sides of the pipeline casing 2, with each layer thickness controlled within 200mm. After compaction, the monitoring data from the monitoring unit is read, and the tension of the corresponding vertical hanging rods 3 is finely adjusted to counteract the lateral pressure bending moment. Backfilling is carried out layer by layer to the design elevation. Finally, drainage ditches are constructed on both sides of the foundation pit 5, the construction site is cleaned, and all protective construction is completed.

[0091] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A bridge abutment pile foundation isolation and protection structure adjacent to a pipeline, installed outside the underground communication optical cable within the foundation construction pit, characterized in that, This includes the upper hanger, pipeline casing, and multiple vertical hangers; The upper suspension rod is laid out along the axis parallel to the underground communication optical cable, and the two ends of the upper suspension rod are respectively anchored to the slope soil on both sides of the foundation construction pit; The pipeline casing includes a C-shaped casing and multiple sets of fasteners. The C-shaped casing covers the outside of the underground communication optical cable. Both ends of the pipeline casing extend and are anchored to the slope soil on both sides of the foundation construction pit. The multiple sets of fasteners are spaced apart along the axial direction of the underground communication optical cable to lock and fix the joints of the C-shaped casing. The vertical suspension rods are arranged radially at intervals along the underground communication optical cable. The upper end of each vertical suspension rod is fixedly connected to the upper suspension rod, and the lower end of each vertical suspension rod is fixedly connected to the pipeline casing.

2. The bridge abutment pile foundation isolation and protection structure near a pipeline according to claim 1, characterized in that, The C-shaped sheath is formed by interlocking two C-shaped steels with opposite openings to create a closed protective cavity. The underground communication optical cable is housed within the closed protective cavity. A flexible buffer layer is filled between the inner wall of the C-shaped sheath and the outer wall of the underground communication optical cable. The flexible buffer layer is evenly wrapped around the outer wall of the underground communication optical cable. The opening end of the C-shaped steel is provided with a corner structure.

3. The bridge abutment pile foundation isolation and protection structure near a pipeline according to claim 1, characterized in that, The maximum axial spacing L between two adjacent sets of the fasteners satisfies the following formula: ； In the formula: The section bending modulus of the C-shaped shell; The flexural modulus of the underground communication optical cable body; This is the design value for the flexural strength of the C-shaped shell material; The standard value of the total self-weight per unit length of the pipeline sheath and the underground communication optical cable; The standard value of the equivalent uniformly distributed collision load for bridge abutment foundation construction; This is the dynamic load amplification factor for construction, with a value ranging from 1.3 to 1.

8.

4. The bridge abutment pile foundation isolation and protection structure near a pipeline according to claim 1, characterized in that, The fastener includes a C-clamp and a retaining plate, which are secured by fasteners.

5. The bridge abutment pile foundation isolation and protection structure near a pipeline according to claim 1, characterized in that, Both ends of the upper suspension rod and the pipeline casing are provided with inverted trapezoidal anchoring sections. After the inverted trapezoidal anchoring sections are buried in the slope soil, they are filled with cement. The vertical suspension rod is an adjustable length tie rod structure.

6. The bridge abutment pile foundation isolation and protection structure near a pipeline according to claim 5, characterized in that, The inverted trapezoidal anchoring section is buried at a depth of at least 300 mm.

7. The bridge abutment pile foundation isolation and protection structure near a pipeline according to claim 1, characterized in that, It also includes a monitoring unit, which includes a vibrating wire strain sensor installed on the outer wall of the underground gas pipeline, an optical cable stress sensor installed inside the pipeline casing, and a wireless acquisition and early warning terminal.

8. A construction method for a bridge abutment pile foundation isolation and protection structure adjacent to a pipeline as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1 pipeline exploration and positioning: Before the foundation construction pit is excavated, the plane position, burial depth and direction of the underground gas pipeline and the underground communication optical cable are determined; S2 Foundation Pit Layered Excavation: Determine the slope coefficient according to the soil type, and excavate the foundation construction pit in layers. When the excavation reaches the elevation of the underground communication optical cable, manually remove the soil and expose the underground communication optical cable. S3 pipeline casing installation: Clean the soil adhering to the outer wall of the underground communication optical cable, fasten the C-shaped casing to cover the outside of the underground communication optical cable, install the fixing parts at intervals along the axial direction and lock them, adjust the axial position of the pipeline casing so that its two ends are respectively anchored to the slope soil on both sides of the foundation construction pit; S4 Suspension System Assembly: The upper suspension rod is installed at the top of the foundation construction pit along the axis parallel to the underground communication optical cable. The two ends of the upper suspension rod are anchored to the slope soil on both sides. Multiple vertical suspension rods are installed, and the upper end of the vertical suspension rod is fixedly connected to the upper suspension rod, and the lower end is fixedly connected to the pipeline casing. S5 monitoring deployment: Install the monitoring unit and set the strain early warning threshold, construct a horizontal load isolation structure above the underground gas pipeline, and backfill the foundation construction pit in layers; S6 Site Restoration: Construct longitudinal drainage ditches on both sides of the foundation construction pit to complete the construction.

9. The construction method of a bridge abutment pile foundation isolation and protection structure adjacent to a pipeline according to claim 8, characterized in that, In step S5, a lateral pressure synchronous balance layered backfilling process is adopted. The earthwork backfilling is carried out symmetrically and synchronously along both sides of the pipeline shell. The thickness of each backfilling layer is no more than 200mm. After each layer of backfilling is completed, the soil lateral pressure data on both sides of the pipeline shell is collected through the monitoring unit, and the tension of the vertical hanger at the corresponding position is adjusted synchronously to counteract the additional bending moment generated by the lateral pressure.

10. The construction method of the bridge abutment pile foundation isolation and protection structure near a pipeline according to claim 9, characterized in that, The final consolidation settlement is calculated based on the compression modulus of the backfill soil and the thickness of the cover soil, and the preset lifting amount of the pipeline casing is determined.

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