Support system and support method for construction of coastal facies silt geological crown beam

Abstract

The application discloses a kind of coastal facies silt geology crown beam construction support system and supporting method, it is related to coastal facies silt geology crown beam construction support technical field, technical scheme is, including outer support system, inner support system and hydraulic jack;Outer support system includes two symmetrical outer protective plates arranged in the both sides of crown beam;Inner support system includes several evenly distributed support beams arranged between the top of two outer protective plates and two symmetrical inner protective plates arranged in the both sides of crown beam;Several evenly distributed hydraulic jacks are arranged between outer protective plate and inner protective plate.The beneficial effects of the present application are: through the synergistic effect of outer support system, inner support system and hydraulic jack, a spatial force system is formed.The outer support system effectively resists horizontal soil pressure, the H-shaped steel of the inner support system controls the rebound of the base, and the hydraulic jack dynamically balances the uneven load.

Description

Technical Field

[0001] This invention relates to the field of cap beam construction and support technology in coastal silty geology, and particularly to a support system and method for cap beam construction in coastal silty geology. Background Technology

[0002] When constructing capping beams in coastal silty geological conditions, traditional methods are prone to problems such as soil slippage, formwork deformation, and even collapse due to the soft, water-rich, low-bearing-capacity, and easily flowing geology. Furthermore, the high water content, low bearing capacity, high compressibility, and strong rheological properties of the silt layer make it difficult for traditional support methods to meet stability requirements. Disturbed silty soil is prone to lateral flow, base heave, or piping, leading to deformation or even failure of the support structure, severely impacting construction safety and project progress.

[0003] The existing technology has the following main limitations: 1. Shortcomings of conventional support systems: Sheet pile support is prone to deviation in deep silt, and poor interlocking between piles can lead to leakage problems; cement-soil mixing piles are affected by organic matter in the silt, resulting in poor solidification and difficulty in guaranteeing pile strength; soil nailing wall support often suffers from surface cracking and soil nail pull-out due to the poor self-stabilizing ability of the soil.

[0004] 2. Impact on the water environment: The high groundwater level in coastal areas is subject to periodic fluctuations due to tidal forces, generating dynamic water pressure that further exacerbates the risk of seepage in the foundation pit. The low permeability coefficient of silt means that conventional dewatering measures have limited effectiveness. Long-term pumping can easily lead to ground subsidence in the surrounding area, threatening the safety of nearby buildings.

[0005] 3. Challenges in Deformation Control: The rheological properties of silt cause continuous deformation of the support structure, which traditional rigid supports cannot adapt to; uneven settlement of the cap beam can easily cause stress concentration in the support system, resulting in damage to the connection nodes; uneven settlement or horizontal displacement can cause cracking of the cap beam, thereby affecting the stability of the overall support system.

[0006] 4. Defects in construction techniques: Large machinery and equipment have difficulty operating on soft foundations, which can easily cause foundation disturbance.

[0007] To address the aforementioned issues, there is an urgent need for an efficient, stable, and adaptable method for capping beam construction and support suitable for coastal silty geology, capable of effectively controlling deformation under soft soil conditions and ensuring construction safety during foundation pit excavation and capping beam pouring. Summary of the Invention

[0008] In order to achieve the above-mentioned objectives and address the above-mentioned technical problems, the present invention provides a support system and method for the construction of cap beams in coastal silty geology.

[0009] The technical solution is a support system for the construction of cap beams in coastal silty geology, including an external support system, an internal support system, and hydraulic jacks; The external support system includes two symmetrically arranged external protective plates on both sides of the cap beam; The internal support system includes several evenly distributed support beams disposed between the tops of the two outer protective plates and two symmetrically arranged inner protective plates on both sides of the cap beam. Several evenly distributed hydraulic jacks are arranged between the outer protective plate and the inner protective plate; The outer protective plate includes interconnected outer protective vertical plates, outer protective inclined plates, and outer protective horizontal plates; The inner protective plate is L-shaped, including an inner protective vertical plate and an inner protective horizontal plate; The support beam is made of H-beams.

[0010] The inner walls of the two inner protective plates are matched with the crown beam.

[0011] The two outer protective horizontal plates and the two inner protective plates are located on both sides of the top of the steel pipe pile.

[0012] The hydraulic jacks are installed between the outer protective vertical plate and the inner protective vertical plate, and between the outer protective inclined plate and the inner protective vertical plate; The fixed end of the hydraulic jack is fixedly connected to the outer protective vertical plate and the outer protective inclined plate, respectively, and the telescopic end of the hydraulic jack is fixedly connected to the outer wall of the inner protective vertical plate.

[0013] The outer protective inclined plate is inclined; The supporting beam is horizontally braced between the two outer protective vertical plates; The support beams are of model H400×400×13×21, installed at 3.0m intervals, and provide internal prestress. The hydraulic jack is of the 200t class.

[0014] The outer protective plate is provided with an external support steel pipe diagonal brace on the inner side of the outer wall at the end. The external support steel pipe diagonal brace is made of φ219×10mm steel pipe, which penetrates the silt layer into the stable bearing layer at an inclination angle of 55°±5°. It is arranged at a spacing of 2.5m to form an external anti-slip constraint. The upper end is connected by a flange, and the lower end is provided with an enlarged bearing plate to reduce the foundation stress.

[0015] The support method for the support system of the cap beam construction based on coastal silty geology includes the following steps: S1. Site survey and surveying / setting out Before construction, a supplementary engineering geological survey was conducted, focusing on determining the thickness of the silt layer, its physical and mechanical properties, and the groundwater conditions; a total station was used for surveying and setting out to establish a construction control network. The concrete foundation layer was poured and compacted using a plate vibrator. S2, Support System Installation After the steel pipe pile construction is completed, the area where the capping beam construction is required needs to be excavated, down to below the capping beam construction elevation; An external support system for the cap beam construction support system is set up in the excavation area of ​​the cap beam, and a support beam is erected on the upper part to ensure the stability of the support system; the support beam is hoisted by two truck cranes; the H-shaped steel support beam is prefabricated in the factory and reinforced ribs are welded to the ends; the ends of the inner protective plate are connected to the embedded parts of the cap beam with high-strength bolts. An internal support system is installed on both sides of the steel pipe pile to increase the overall support stability and provide a point of force for the hydraulic jack support; Hydraulic jacks are installed between the external support system of the cap beam excavation area and the internal support system of the cap beam formwork. The hydraulic jacks apply axial loads step by step by lifting the piston rod at a constant speed. The pressure value is fed back in real time through a digital display instrument to ensure that the pressure reaches the set value. S3, Construction of the main structure of the capping beam Reinforcement Engineering The main reinforcement bars are connected by straight threaded sleeves, and the web reinforcement bars are fixed to the main reinforcement bars by welding. Template Engineering Standardized steel formwork is used for assembly, and closed-cell foam sealing strips are pasted at the joints of the formwork. The formwork is reinforced with φ16 tie bolts, and the verticality is checked after the formwork is installed. Concrete pouring The concrete was poured in layers using a truck-mounted pump, and a φ50 immersion vibrator was used for compaction. After pouring, the concrete was immediately covered with geotextile for moisture retention and curing.

[0016] The hydraulic jack applies pressure in stages, including the following phases: Initial preload: Apply 30% of the design axial force and stabilize for 10 minutes; Secondary loading: Increase to 60% of the design axial force and stabilize for 15 minutes; Three loading cycles: Increase to 90% of the design axial force, stabilize for 20 minutes; Final loading: Reach 100% of the design axial force and stabilize for 30 minutes.

[0017] After the concrete strength of the cap beam reaches the design requirements, first release the pressure of the hydraulic jacks, remove the hydraulic jacks, dismantle the inner support system and cap beam formwork outside the cap beam, remove the support beams on the upper part of the outer support system, and finally dismantle the outermost outer support system.

[0018] Before tensioning the anchor bars with the pre-set steel strands in the cap beam, the tensioning slope is ground flat in advance, a 180×310×20 steel pad is placed, and then the anchor is installed for tensioning.

[0019] A φ219×10mm external support steel pipe diagonal brace is installed on the outside of the cap beam. The external support steel pipe diagonal brace penetrates the silt layer into the stable bearing layer at an inclination angle of 55°±5°. The horizontal spacing is 2.5m. The upper end is connected by a flange, and the lower end is equipped with an enlarged bearing plate to reduce the foundation stress.

[0020] The support beams are of model H400×400×13×21 and are set at 3.0m intervals to provide internal prestress; adjustable supports are set at the ends of the supports and fixed to the cap beam formwork brackets.

[0021] The beneficial effects of the technical solution provided by this invention are as follows: This solution addresses the technical challenges of traditional support methods in coastal silty geology, such as large deformation, poor stability, and weak adaptability of the support structure. It provides a support system and method for capping beam construction in coastal silty geology. Through the synergistic action of the external support system, internal support system, and hydraulic jacks, a spatial force-bearing system is formed. The external support system effectively resists horizontal earth pressure, the H-beams of the internal support system control the foundation rebound, and the hydraulic jacks dynamically balance uneven loads. Actual engineering monitoring data shows that this system can effectively control the horizontal displacement of the capping beam within a safe range.

[0022] The successful application of this construction method has pioneered a brand-new construction approach for similar cap beam support construction. By employing external support + hydraulic jacks + internal support, it solves the difficulties in cap beam construction caused by the excessive fluidity of the geological silt soil, providing safe and reliable construction conditions for cap beam construction, reducing large-area earthwork excavation, lowering costs, shortening the construction period, and reducing construction difficulty. It greatly reduces soil and water loss caused by gaps between piles, uses minimal materials to complete a solid and stable construction system, and the tools and materials used for support can be reused multiple times, effectively reducing material waste, reducing project costs, and meeting the requirements of green construction.

[0023] This construction method is applicable to the construction of capping beam support in coastal silty geology, especially for projects with poor geology, high soil fluidity, and complex geological conditions within the excavation area, where large-scale excavation for capping beam support is unsuitable. It fully demonstrates the exemplary role of building technology development based on project entities and has significant potential for widespread application. This support method achieves comprehensive benefits of "safety and controllability, economic rationality, and environmental friendliness" through technological innovation, providing a reliable technical solution for engineering construction under coastal silty geological conditions. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention. Figure 1.

[0025] Figure 2 This is a schematic diagram of the overall structure of an embodiment of the present invention. Figure 2 .

[0026] Figure 3 This is a schematic diagram of the overall structure of an embodiment of the present invention. Figure 3 .

[0027] The attached diagram is labeled as follows: 4. Hydraulic jack; 100. Crown beam; 1. Outer protective plate; 2. Support beam; 3. Inner protective plate; 101. Outer protective vertical plate; 102. Outer protective inclined plate; 103. Outer protective horizontal plate; 301. Inner protective vertical plate; 302. Inner protective horizontal plate; 200. Steel pipe pile. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0030] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] Example 1 See Figures 1 to 3 This invention provides a support system for the construction of cap beams in coastal silty geology, including an external support system, an internal support system, and hydraulic jacks 4; The external support system includes two symmetrically arranged external protective plates 1 on both sides of the cap beam 100; The internal support system includes several evenly distributed support beams 2 set between the tops of the two outer protective plates 1 and two symmetrically arranged inner protective plates 3 on both sides of the cap beam 100; Several evenly distributed hydraulic jacks 4 are arranged between the outer protective plate 1 and the inner protective plate 3; The outer protective plate 1 includes an outer protective vertical plate 101, an outer protective inclined plate 102, and an outer protective horizontal plate 103 that are connected to each other; The inner protective plate 3 is L-shaped, including an inner protective vertical plate 301 and an inner protective horizontal plate 302; Support beam 2 is made of H-beams.

[0033] The inner walls of the two inner protective plates 3 are matched with the crown beam 100.

[0034] The two outer protective horizontal plates 103 and the two inner protective plates 3 are located on both sides of the top of the steel pipe pile 200.

[0035] Hydraulic jacks 4 are installed between the outer protective vertical plate 101 and the inner protective vertical plate 301, and between the outer protective inclined plate 102 and the inner protective vertical plate 301; The fixed end of the hydraulic jack 4 is fixedly connected to the outer protective vertical plate 101 and the outer protective inclined plate 102 respectively, and the telescopic end of the hydraulic jack 4 is fixedly connected to the outer wall of the inner protective vertical plate 301.

[0036] The outer protective inclined plate 102 is inclined; The support beam 2 is horizontally braced between the two outer protective vertical plates 101; Support beam 2 is of model H400×400×13×21, and is set at 3.0m intervals to provide internal prestress; The hydraulic jack 4 is a 200t class jack, which achieves dynamic force system balance.

[0037] An external support steel pipe diagonal brace is installed on the inner side of the outer wall at the end of the outer protective plate 1. The external support steel pipe diagonal brace uses φ219×10mm steel pipe, which penetrates the silt layer into the stable bearing layer at an inclination angle of 55°±5°. It is arranged at a spacing of 2.5m to form an external anti-slip constraint. The upper end is connected by a flange, and the lower end is equipped with an enlarged bearing plate to reduce the foundation stress.

[0038] The support method for the support system of the cap beam construction based on coastal silty geology includes the following steps: S1. Site survey and surveying / setting out Before construction, a supplementary engineering geological survey was conducted, focusing on determining the thickness of the silt layer, its physical and mechanical properties, and the groundwater conditions; a total station was used for surveying and setting out to establish a construction control network. The concrete foundation layer was poured and compacted using a plate vibrator. S2, Support System Installation After the steel pipe pile 200 is completed, the area where the capping beam 100 needs to be excavated should be excavated to below the construction elevation of the capping beam. An external support system for the cap beam construction support system is set up in the 100-meter excavation area of ​​the cap beam, and a support beam 2 is installed on the upper part to support it and ensure the stability of the support system. The support beam 2 is lifted by two truck cranes in coordination. The H-shaped steel support beam is prefabricated in the factory and the end is welded with reinforcing ribs. The end of the inner protective plate 3 is connected to the cap beam embedded parts with high-strength bolts. An internal support system is installed on both sides of the 200 steel pipe pile to increase the overall support stability and provide a support point for the hydraulic jack 4. Hydraulic jacks 4 are installed between the external support system of the cap beam excavation area and the internal support system of the cap beam formwork. The hydraulic jacks 4 apply axial load step by step by lifting the piston rod at a constant speed. The pressure value is fed back in real time through a digital display instrument to ensure that the pressure reaches the set value. S3, Construction of the main structure of the capping beam Reinforcement Engineering The main reinforcement bars are connected by straight threaded sleeves, and the web reinforcement bars are fixed to the main reinforcement bars by welding. Template Engineering Standardized steel formwork is used for assembly, and closed-cell foam sealing strips are pasted at the joints of the formwork. The formwork is reinforced with φ16 tie bolts, and the verticality is checked after the formwork is installed. Concrete pouring The concrete was poured in layers using a truck-mounted pump, and a φ50 immersion vibrator was used for compaction. After pouring, the concrete was immediately covered with geotextile for moisture retention and curing.

[0039] The hydraulic jack applies pressure using a staged loading method, including the following stages: Initial preload: Apply 30% of the design axial force and stabilize for 10 minutes; Secondary loading: Increase to 60% of the design axial force and stabilize for 15 minutes; Three loading cycles: Increase to 90% of the design axial force, stabilize for 20 minutes; Final loading: Reach 100% of the design axial force and stabilize for 30 minutes.

[0040] After the concrete strength of the cap beam reaches the design requirements, first release the pressure of hydraulic jack 4, remove hydraulic jack 4, dismantle the inner support system and cap beam formwork outside the cap beam, remove the support beam 2 on the upper part of the outer support system, and finally dismantle the outermost outer support system.

[0041] Before tensioning the anchor bars with the pre-set steel strands in the cap beam, the tensioning slope is ground flat in advance, a 180×310×20 steel pad is placed, and then the anchor is installed for tensioning.

[0042] A φ219×10mm external support steel pipe diagonal brace is installed on the outside of the cap beam. The external support steel pipe diagonal brace penetrates the silt layer into the stable bearing layer at an inclination angle of 55°±5°. The horizontal spacing is 2.5m. The upper end is connected by a flange, and the lower end is equipped with an enlarged bearing plate to reduce the foundation stress.

[0043] Support beam 2 is of model H400×400×13×21, set at 3.0m intervals, and provides internal prestress; adjustable supports are set at the ends of the support and fixed to the cap beam formwork support.

[0044] The first step in the construction preparation stage is to conduct surveying and setting out: establish a construction control network with an accuracy controlled within ±5mm. And material preparation: steel arrival inspection and concrete mix design.

[0045] During the construction of the capping beam support, after the retaining piles are completed and the steel pipe piles reach the design strength or age requirements, the excavation boundaries for the capping beam and its support are determined by surveying and setting out. An excavator is then used to excavate the capping beam to the bottom, and the excavated soil is removed to the design bottom elevation. Disturbance to the steel pipe piles and sheet piles is minimized during excavation. After the capping beam foundation trench excavation is completed, a 30cm thick C20 plain concrete cushion layer is constructed, with surface flatness controlled within ±10mm, meeting the minimum requirement for pile penetration into the capping beam during construction. An external support system is installed on top of the concrete cushion layer, and an additional support beam 2 is added on top to prevent the capping beam from being obstructed by silty soil flow and to enhance soil stability. An internal support system for the capping beam formwork is installed within the capping beam construction area at the top of the steel pipe piles and sheet piles to provide conditions for the capping beam construction. After the support is completed, hydraulic jacks are used to pressurize and fix the internal and external support systems to ensure the system is solid and stable.

[0046] During the construction of the capping beam, attention should be paid to the lap joint requirements when binding and installing the capping beam reinforcement. A 50% lap joint should be used, with a lap length of 49d, and the pile body should be inside the capping beam reinforcement. The capping beam is constructed in sections, with connecting reinforcement reserved at the joints of each section. The main reinforcement is C25, and the stirrups are A8@200. After the capping beam formwork is installed, before pouring concrete, the anchor cable positions are determined, and A75 rigid PVC pipes are pre-embedded for anchor cable tensioning. After construction is completed, daily jack pressure tests and stability checks of the support system are conducted.

[0047] Example 2 Based on Example 1, this solution forms a support system that works collaboratively through an external support system, an internal support system, and hydraulic jacks. The support method includes the following steps: S1. Site survey and surveying / setting out Prior to construction, a supplementary engineering geological survey was conducted, focusing on determining the thickness of the silt layer, its physical and mechanical properties, and the groundwater conditions. A total station was used for surveying and setting out, establishing a construction control network with horizontal control points spaced no more than 50m apart and vertical control points spaced no more than 30m apart. All control points were closed-loop surveyed, with horizontal position errors controlled within ±5mm and vertical errors within ±3mm.

[0048] Subbase construction Pour a 30cm thick C20 plain concrete subbase and compact it using a plate vibrator. The surface flatness of the subbase should be checked with a 2m straightedge, with a deviation not exceeding 10mm. The subbase should be cured for at least 3 days, and the next process can only proceed after the strength reaches 5MPa.

[0049] S2, Support System Installation 2.1 Construction of External Support System Measurement and positioning: A total station is used for precise positioning, marking the plane position and elevation of each support point, with the error controlled within ±5mm.

[0050] Guide frame installation: Install adjustable guide frames to ensure the verticality of the steel pipes. The rigidity of the guide frames must meet construction requirements, and the deformation should not exceed 2mm.

[0051] Steel pipe driving: Hydraulic vibratory hammers are used for pile driving. In the initial stage, a low setting (frequency 15-20Hz) is used for slow driving. After entering the bearing layer, the frequency is increased to 25-30Hz. Verticality is monitored in real time during pile driving. If the deviation exceeds 1 / 200, it needs to be corrected in time.

[0052] Pile end treatment: After the pile is driven into place, C25 micro-expansion concrete is poured to seal the bottom of the pile end with a thickness of not less than 50cm.

[0053] 2.2 Installation of Internal Support System Support beam fabrication: H-beam support beams are prefabricated in the factory, with 20mm thick reinforcing ribs welded to the ends. All welds must undergo ultrasonic testing, with a quality grade no lower than B.

[0054] On-site assembly: First, install support beam 2, using two truck cranes for coordinated lifting. Once support beam 2 is in place, immediately install temporary fixing devices.

[0055] Node connection: The inner protective plate 3 ends are connected to the pre-embedded parts of the crown beam with high-strength bolts. The bolts are tightened in three stages, and the final torque reaches ±5% of the design value.

[0056] 2.3 Hydraulic Jack Installation Jack arrangement: Two 200t hydraulic jacks are set for each support beam, and the deviation between the center line of the hydraulic jacks and the support axis is no more than 3mm.

[0057] Hydraulic circuit connection: High-pressure hydraulic hoses are used for connection, with the working pressure set at 31.5 MPa. After installation, a pressure test at 1.5 times the working pressure is required, and the pressure should be maintained for 10 minutes without leakage.

[0058] Sensor Installation: Displacement sensors are fixed on a dedicated bracket, with the measurement direction aligned with the support axis. Pressure sensors are installed in the hydraulic system and require zero-point calibration before installation.

[0059] S3, Construction of the main structure of the capping beam 3.1 Reinforcement Engineering The main reinforcement bars are connected using straight threaded sleeves, with a joint grade of Class I and a joint rate of no more than 50% in the same cross-section. The web reinforcement bars are fixed to the main reinforcement bars by welding, with a weld length of no less than 10d. The installation position deviation of the embedded parts is no more than 5mm, and a second check is required after fixing.

[0060] 3.2 Formwork Engineering Standardized steel formwork is used for assembly, with 10mm thick closed-cell foam sealing strips affixed to the joints. The formwork is reinforced with φ16 tie bolts spaced 600mm x 600mm. After installation, the formwork must be checked for verticality, with deviations controlled within 1 / 500.

[0061] 3.3 Concrete Pouring The concrete is poured in layers using a truck-mounted pump, with each layer no thicker than 50cm. Vibration is performed using a φ50 immersion vibrator, with insertion points spaced no more than 40cm apart, and each point vibrating for 20-30 seconds. Immediately after pouring, the concrete is covered with geotextile for moisture retention and curing, which lasts for at least 14 days.

[0062] 3.4 The hydraulic jack applies pressure using a staged loading method. Initial preload: Apply 30% of the design axial force and stabilize for 10 minutes; Secondary loading: Increase to 60% of the design axial force and stabilize for 15 minutes; Three loading cycles: Increase to 90% of the design axial force, stabilize for 20 minutes; Final loading: Reach 100% of the design axial force and stabilize for 30 minutes.

[0063] 3.5 Synchronous Control A PLC control system is used to achieve synchronous lifting of multiple hydraulic jacks, with the synchronization error controlled within ±2mm. During loading, the axial force of the supports is monitored in real time, and the deviation of the axial force between supports does not exceed ±5%.

[0064] 3.6 Displacement Monitoring The displacement of the cap beam was recorded every 5 minutes during loading, and the displacement increment caused by a single loading should not exceed 1 mm. If abnormal displacement was detected, loading was stopped immediately and the cause was analyzed.

[0065] The three-dimensional collaborative support system of external support system, internal support system and hydraulic jacks controls the horizontal displacement of the crown beam within a safe range, reducing the deformation by more than 40% compared with traditional methods; Hydraulic jacks can counteract the rheological deformation of sludge and control the long-term creep rate within the standard range; The PLC control system enables precise displacement control at the millimeter level (±2mm), meeting the deformation control requirements of the super-grade foundation pit.

[0066] Optimizing the support layout reduces steel consumption by 25-30%. For example, in a 10m deep foundation pit, 0.8 tons of steel are saved per linear meter. Parallel construction of vacuum preloading and support shortens the construction period by 15-20 days and improves overall construction efficiency by 40%.

[0067] Two hydraulic jacks are installed on the same longitudinal section. The redundant design of the double jacks ensures that 50% of the design support force is maintained even if a single machine fails. The emergency power supply system ensures continuous support for 8 hours in the event of a power outage.

[0068] This solution has been successfully applied to fluid-plastic silt formations with a water content of 60-80% and a sensitivity of 4-8; it supports a recovery rate of over 95%, and the hydraulic system can be reused more than 50 times; it can be seamlessly integrated with an intelligent monitoring platform and BIM system to support digital construction site development.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A support system for constructing cap beams in coastal silty geology, characterized in that, Including external support system, internal support system and hydraulic jack (4); The external support system includes two symmetrically arranged external protective plates (1) on both sides of the cap beam (100); The internal support system includes several evenly distributed support beams (2) between the tops of the two outer protective plates (1) and two symmetrically arranged inner protective plates (3) on both sides of the cap beam (100). Several evenly distributed hydraulic jacks (4) are arranged between the outer protective plate (1) and the inner protective plate (3); The outer protective plate (1) includes an outer protective vertical plate (101), an outer protective inclined plate (102), and an outer protective horizontal plate (103) that are connected to each other. The inner protective plate (3) is L-shaped and includes an inner protective vertical plate (301) and an inner protective horizontal plate (302). The supporting beam (2) is made of H-beams; The inner walls of the two inner protective plates (3) are matched with the crown beam (100); The two outer protective horizontal plates (103) and the two inner protective plates (3) are located on both sides of the top of the steel pipe pile (200); Hydraulic jacks (4) are provided between the outer protective vertical plate (101) and the inner protective vertical plate (301), and between the outer protective inclined plate (102) and the inner protective vertical plate (301), that is, two hydraulic jacks (4) are provided on the same longitudinal section. The fixed end of the hydraulic jack (4) is fixedly connected to the outer protective vertical plate (101) and the outer protective inclined plate (102) respectively, and the telescopic end of the hydraulic jack (4) is fixedly connected to the outer wall of the inner protective vertical plate (301). The outer protective inclined plate (102) is inclined; The supporting beam (2) is horizontally braced between the two outer protective vertical plates (101); The support beam (2) adopts model H400×400×13×21 and is set at a spacing of 3.0m to provide internal prestress; The hydraulic jack (4) adopts a 200t class to achieve dynamic force system balance.

2. The support system for capping beam construction in coastal silty geology according to claim 1, characterized in that, The outer protective plate (1) is provided with an external support steel pipe diagonal brace on the inner side of the outer wall. The external support steel pipe diagonal brace is made of φ219×10mm steel pipe, which penetrates the silt layer into the stable bearing layer at an inclination angle of 55°±5°. It is arranged at a spacing of 2.5m to form an external anti-slip constraint. The upper end is connected by a flange, and the lower end is provided with an enlarged bearing plate to reduce the foundation stress.

3. A support method for the support system of the cap beam construction in coastal silty geology according to any one of claims 1-2, characterized in that, Includes the following steps: S1. Site survey and surveying / setting out Before construction, a supplementary engineering geological survey was conducted, focusing on determining the thickness of the silt layer, its physical and mechanical properties, and the groundwater conditions; a total station was used for surveying and setting out to establish a construction control network. The concrete foundation layer was poured and compacted using a plate vibrator. S2, Support System Installation After the steel pipe pile (200) construction is completed, the area where the capping beam (100) construction is required is excavated to the level below the capping beam construction elevation; An external support system for the construction support system of the crown beam (100) is set up in the excavation area, and a support beam (2) is set up on the upper part for support; the support beam (2) is hoisted by two truck cranes; the H-shaped steel support beam is prefabricated in the factory and the end is welded with reinforcing ribs; the end of the inner protective plate (3) is connected to the embedded parts of the crown beam with high-strength bolts. An internal support system is set on both sides of the steel pipe pile (200) to provide a support point for the hydraulic jack (4); Hydraulic jacks (4) are installed between the external support system of the cap beam excavation area and the internal support system of the cap beam formwork. The hydraulic jacks (4) apply axial loads step by step. S3, Construction of the main structure of the capping beam Reinforcement Engineering The main reinforcement bars are connected by straight threaded sleeves, and the web reinforcement bars are fixed to the main reinforcement bars by welding. Template Engineering Standardized steel formwork is used for assembly, and closed-cell foam sealing strips are pasted at the joints of the formwork. The formwork is reinforced with φ16 tie bolts, and the verticality is checked after the formwork is installed. Concrete pouring The concrete was poured in layers using a truck-mounted pump, and a φ50 immersion vibrator was used for compaction. After pouring, the concrete was immediately covered with geotextile for moisture retention and curing.

4. The support method for the support system of the cap beam construction in coastal silty geology according to claim 3, characterized in that, The hydraulic jack (4) applies pressure using a staged loading method. Includes the following stages: Initial preload: Apply 30% of the design axial force and stabilize for 10 minutes; Secondary loading: Increase to 60% of the design axial force and stabilize for 15 minutes; Three loading cycles: Increase to 90% of the design axial force, stabilize for 20 minutes; Final loading: Reach 100% of the design axial force and stabilize for 30 minutes.

5. The support method for the support system of the cap beam construction in coastal silty geology according to claim 4, characterized in that, After the concrete strength of the cap beam reaches the design requirements, first release the pressure of the hydraulic jack (4), remove the hydraulic jack (4), dismantle the inner support system and cap beam template outside the cap beam, remove the support beam (2) on the upper part of the outer support system, and finally dismantle the outermost outer support system. Before tensioning the anchor bars with the pre-set steel strands in the cap beam, the tensioning slope is ground flat in advance, a 180×310×20 steel pad is placed, and then the anchor is installed for tensioning.

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