Press-in type open caisson construction method based on automatic control system

Abstract

The invention discloses a press-in type open caisson construction method based on an automatic control system. The automatic control system comprises a data acquisition module, a data analysis and decision module and an execution control module. The data acquisition module is used for collecting data in the sinking process of the open caisson in real time, the data analysis and decision module analyzes the collected data in real time and generates a control instruction, and the execution control module regulates and controls the pressure sinking equipment and the soil sampling equipment according to the control instruction; the construction method comprises the following steps: constructing a ground anchor pile; isolation pile construction; construction of the open caisson: surveying and setting out, excavating a foundation pit, laying a sand cushion layer, laying a concrete cushion layer, constructing a brick moulding bed, erecting a scaffold, erecting a template, binding reinforcing steel bars and pouring concrete; pressing and sinking the open caisson; according to the method, an automatic control system is adopted, various parameters in the open caisson construction process can be monitored and adjusted in real time, uniform sinking of the open caisson is achieved through accurate control over the parameters, and the construction precision and quality are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of building construction, and in particular relates to a press-in type caisson construction method based on an automatic control system. Background Art

[0002] Among existing caisson construction technologies, common options for circular caisson structures include forward excavation after foundation pit support, reverse excavation of the caisson wall after foundation pit support, conventional caissons, and press-in caissons. Forward excavation after foundation pit support is time-consuming and expensive; reverse excavation of the caisson wall after foundation pit support is not only time-consuming and difficult to construct, but also presents issues such as vertical load-bearing capacity of the caisson wall and joint waterproofing. Conventional caissons, while convenient and fast, can easily deflect in complex environments due to uneven soil extraction, and excavation can cause deformation of the surrounding soil, impacting the safety of surrounding objects.

[0003] Most of the existing patents related to the press-in caisson construction method do not fully consider the complex surrounding environment, and have shortcomings in controlling the disturbance of the surrounding soil, ensuring the safety of surrounding facilities, and improving construction efficiency and automation. Summary of the Invention

[0004] Based on the above technical problems, the present invention aims to provide a push-in caisson construction method based on an automatic control system to solve the problems of large disturbance to the surrounding soil and easy deflection caused by caisson construction when the surrounding environment is complex, as well as the long construction period of traditional construction methods.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A method for constructing a press-in caisson based on an automatic control system, wherein the automatic control system comprises a data acquisition module, a data analysis and decision module, and an execution control module;

[0007] The data acquisition module is used to collect data in real time during the sinking process of the caisson, the data analysis and decision module analyzes the collected data in real time and generates control instructions, and the execution control module regulates the sinking equipment and the soil sampling equipment according to the control instructions;

[0008] The construction method comprises:

[0009] Step S1, ground anchor pile construction: using cast-in-place piles as ground anchor piles;

[0010] Step S2, isolation pile construction;

[0011] Step S3, caisson construction: measurement and layout, foundation pit excavation, laying of sand cushion layer, laying of concrete cushion layer, brick formwork construction, scaffolding erection, and caisson fabrication;

[0012] Step S4, sinking the caisson;

[0013] Specifically, step S4 includes:

[0014] Preparation before sinking: Before sinking, the concrete cushion and brick formwork at the caisson foot are removed, measurement marks are drawn on the walls around the caisson, and a horizontal indicator is set up. The automatic control system monitors the concrete strength in real time and automatically prompts the user to proceed to the next step when the preset requirements are met.

[0015] Installation of the caisson equipment: Steel brackets are welded at intervals on the outer wall of the caisson, and a jack is installed on each steel bracket. The jack is connected to the anchor pile through a steel strand, and the jack is connected to the automatic control system through a hydraulic system;

[0016] Soil excavation and downward pressure: The automatic control system controls the pressure of the jack at the sinking point based on the measured data of the height difference and inclination of the caisson during initial sinking, and corrects the sinking of the caisson. The automatic control system monitors the excavation process and the sinking status of the caisson in real time;

[0017] Step S5, sealing the bottom of the caisson:

[0018] Specifically, in step S5: after the caisson is sunk to the designed elevation, soil is continuously taken from the caisson, and a 3.5-3.9m thick soil plug is retained; after sinking into place, the caisson is continuously observed for a predetermined time, and the bottom is sealed when the sinking amount is less than 10mm.

[0019] In some embodiments, step S4 further includes arranging a mud box, a slurry mixer, a slurry pump and a slurry delivery pipeline to reduce mud drag during the caisson sinking process.

[0020] In some embodiments, in the step of reducing mud drag, the mud density is controlled to be between 1.10 and 1.3.

[0021] In some of the embodiments, in the step of taking soil and pressing down, the principle of sinking the caisson is to press first and then take soil. The jack starts to apply pressure to the caisson. When the jacking force of the jack reaches a predetermined value, soil is taken from the well. The caisson is sunk by drainage, and a crawler crane equipped with a grab bucket is used to dig soil from the center of the caisson to the surrounding areas to make the caisson sink evenly.

[0022] In some embodiments, the data analysis and decision module includes a data processing and analysis module and a control decision and instruction generation module. The data processing and analysis module performs real-time analysis on the collected data, calculates the settlement amount, inclination, stress conditions of each pressure point and pressure changes of the surrounding soil of the caisson; the control decision and instruction generation module compares and analyzes the calculation results of the data processing module with the preset construction parameters and standards to automatically generate control instructions.

[0023] In some embodiments, the data acquisition module includes: structural safety monitoring sensors, construction process monitoring sensors, special process monitoring sensors and environment monitoring sensors.

[0024] In some embodiments, the structural safety monitoring sensors include tilt sensors, settlement sensors, earth pressure sensors, displacement sensors, vibration sensors, and strain sensors;

[0025] The construction process monitoring sensors include laser ranging sensors; temperature and humidity sensors, pressure sensors, flow sensors, density sensors, pH sensors, ultrasonic sensors and infrared temperature sensors;

[0026] The special process monitoring sensors include verticality sensors, torque sensors, acoustic emission sensors, laser scanning sensors and fiber grating sensors;

[0027] The environmental monitoring sensors include pore water pressure gauges, groundwater level gauges, wind speed sensors and

[0028] Video surveillance camera.

[0029] In some of the embodiments, during the caisson construction process, the soil pressure sensors and displacement sensors are buried around and at the bottom of the caisson according to design requirements, and pressure sensors and displacement sensors are installed on the jacks and steel strands.

[0030] In some embodiments, step S3 specifically includes:

[0031] Step S31, surveying and setting out: Before construction, an automatic control system is used to measure and position the caisson, and coordinate control points and temporary leveling points are arranged around the caisson. The automatic control system is used to regularly check and re-measure, gantry piles are set around the caisson, and the center axis of the caisson and the foundation pit outline are marked with lime powder;

[0032] Step S32, excavation of the foundation pit: when the soil is excavated to an elevation of 19 to 21 cm from the pit bottom, artificial slope repair and bottom leveling are performed, a gravel blind ditch and a water collection well are set at the bottom of the caisson foundation pit, and an automatic control system monitors the excavation depth and slope stability in real time;

[0033] Step S33: After the foundation pit excavation passes the acceptance inspection, a medium-coarse sand cushion layer is laid and laid in layers, while sprinkling water and vibrating the sand. Before laying the next two layers, the lower layer is automatically checked to see if it meets the requirements.

[0034] Step S34, laying a concrete cushion layer: laying a concrete cushion layer on the sand cushion layer, under the bottom beam and the blade foot;

[0035] Step S35, brick formwork construction: after the concrete cushion layer on the sand cushion layer reaches a preset strength, the caisson plane position is measured and placed by the automatic control system, and brick formwork construction is carried out;

[0036] Step S36, scaffolding erection: When the first section of the caisson is made, the inner and outer scaffolding are erected directly on the sand cushion layer; during the sinking of the caisson, the inner and outer scaffolding are dismantled. During the process of raising the caisson, the outer scaffolding is still erected on the ground, and the inner scaffolding adopts a cantilever scaffolding.

[0037] Step S37, caisson construction: the caisson is constructed in multiple times.

[0038] In some embodiments, in step S4, the brick formwork is removed when the concrete strength of the caisson reaches 70%, the concrete strength of the caisson reaches 100% of the design strength when the first section sinks, and the concrete strength of the remaining sections is not less than 70% when they sink.

[0039] Compared with the prior art, the present invention has at least one of the following advantages or beneficial effects:

[0040] 1. Automatic Control System: This invention utilizes an automatic control system that monitors and adjusts various parameters during caisson construction, such as caisson inclination, sinking speed, and soil pressure, in real time. By precisely controlling these parameters, the caisson sinks evenly, avoiding caisson deflection caused by localized uneven sinking and improving construction accuracy and quality. Compared to other push-in caisson construction methods, this makes the construction process more intelligent and automated, reducing manual intervention and human error.

[0041] 2. Unique Sinking System: A unique sinking system is created by installing ground anchors, brackets, and through-hole jacks on the caisson's outer wall. This system flexibly adjusts downward pressure at eight different sinking points based on caisson deviation, not only assisting in sinking but also effectively correcting deviation. Compared to existing technologies, this sinking system is more scientifically designed, enabling more precise control of the caisson's sinking direction and speed, significantly improving construction efficiency.

[0042] 3. Earth Pressure Balance and Disturbance Control: This invention utilizes a pre-set soil plug inside the caisson and isolation piles outside the caisson. Combined with an automatic control system, this system precisely controls the earth pressure balance inside and outside the caisson, significantly reducing disturbance to the surrounding soil. Compared to existing technologies, this system is more adaptable to construction scenarios with complex surrounding environments and stringent requirements for controlling foundation settlement and displacement.

[0043] 4. Fast construction speed: By setting ground anchors, brackets and through-type jacks, the downward pressure is used to directly control the uniform sinking of the caisson, making the sinking coefficient proportional to the downward pressure, which greatly improves the construction speed. Taking the swirl pool caisson construction of Baosteel Co., Ltd.'s bar steel plant product structure optimization and transformation project as an example, it took only 120 days from the start of caisson production to the completion of caisson bottom sealing, saving 60 days compared to ordinary caisson construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0045] Figure 1 Flowchart of a push-in caisson construction method based on an automatic control system according to an embodiment of the present invention;

[0046] Figure 2 Schematic diagram of the structure of the pressure sinking equipment in an embodiment of the present invention;

[0047] Figure 3 Schematic cross-sectional view of the caisson sand cushion layer and the concrete cushion layer in an embodiment of the present invention;

[0048] Figure 4 This is a schematic diagram of the first section of caisson construction in an embodiment of the present invention;

[0049] Figure 5 This is a schematic diagram of the prefabrication of the caisson heightening in an embodiment of the present invention;

[0050] Figure 6 A diagram showing the sequence of chiseling out the concrete cushion layer in an embodiment of the present invention;

[0051] Figure 7 Schematic diagram of subsidence excavation in an embodiment of the present invention;

[0052] Figure 8 Schematic diagram of the bottom sealing of the caisson in an embodiment of the present invention;

[0053] Figure numerals: 1. First section of caisson; 2. Sand cushion layer; 3. Water collection well; 4. Brick formwork; 5. Concrete cushion layer; 6. Internal scaffolding; 7. External scaffolding; 8. Formwork; 9. Pump truck; 10. Second section of caisson; 11. Crawler crane; 12. Grab bucket; 13. Cyclone bottom plate; 14. Cyclone table top; 15. Ground anchor pile; 16. Steel corbel; 17. Jack. DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0055] like Figures 1 to 8 As shown, the present invention discloses a pressure-type caisson construction method based on an automatic control system, the automatic control system includes a data acquisition module, a data analysis and decision module and an execution control module; the data acquisition module is used to collect data during the sinking process of the caisson in real time, the data analysis and decision module performs real-time analysis on the collected data and generates control instructions, and the execution control module regulates the pressure-sinking equipment and the soil-taking equipment according to the control instructions.

[0056] Specifically, the steps implemented by the automatic control system include:

[0057] ① Data acquisition: During the caisson construction process, multiple data acquisition modules are installed around the caisson and at key locations of the well body. During the construction process, sensors collect data in real time and transmit the data to the data processing module. Specifically, the data acquisition module may include: structural safety monitoring sensors, construction process monitoring sensors, special process monitoring sensors, and environmental monitoring sensors. Structural safety monitoring sensors include tilt sensors (set at the four corners of the caisson and the middle of each section of the well wall to measure the inclination of the caisson), settlement sensors (set at the bottom of the blade foot and key support points of the well wall to measure real-time settlement), soil pressure sensors (set in the soil below the blade foot and in a ring around the caisson to measure soil pressure changes), displacement sensors (set between the annular base and the caisson and in the surrounding soil to measure soil displacement), vibration sensors (set at the foundation pit slope and scaffolding nodes to measure vibration amplitude) and strain sensors (set at the connection between the ring beam reinforcement and the steel corbel to measure structural strain); Construction process monitoring sensors include laser distance sensors (set at gantry pile benchmarks and wall measuring scales for plane positioning), temperature and humidity sensors (set at sand cushion layer stratification and concrete curing areas for measuring moisture content and temperature), pressure sensors (set at jack oil circuits and grouting pipelines for measuring pressure), flow sensors (set at mud delivery pipelines and drainage pipelines for measuring flow), density sensors (set at mud circulation systems for measuring mud density), pH sensors (set at mud boxes and grouting pipelines for measuring pH), ultrasonic sensors (set at the bottom of foundation pits and water collection wells for measuring water level) and infrared temperature sensors (set at concrete pouring surfaces for measuring concrete density). Special process monitoring sensors include verticality sensors (set at the bottom of foundation pits and water collection wells for measuring water level). These sensors are located on the head of the SMW pile driver and on top of the steel section to measure verticality deviation, a torque sensor (installed on the drive shaft of the three-axis mixing pile to measure mixing torque), an acoustic emission sensor (installed at the interface between the concrete cushion and the blade foot for crack warning), a laser scanning sensor (installed at monitoring points on the caisson's sinking trajectory to measure three-dimensional displacement), and a fiber grating sensor (installed at key structural connections such as ring beam nodes and steel brackets for distributed strain detection). Environmental monitoring sensors include pore water pressure gauges (installed in the surrounding soil to measure pore water pressure), groundwater level gauges (installed in monitoring wells outside the foundation pit to measure water level changes), wind speed sensors (installed on aerial work platforms to measure wind speed), and video surveillance systems (installed at key nodes in each construction area for real-time video monitoring). During caisson construction, these soil pressure sensors and displacement sensors are buried around and at the bottom of the caisson according to design requirements, and pressure sensors and displacement sensors are installed on the jacks and strands.

[0058] ② Data Processing and Decision-Making: This module includes a data processing and analysis module and a control decision-making and instruction generation module. The data processing and analysis module uses professional data analysis software to analyze collected data in real time, calculating parameters such as the caisson's settlement, inclination, the stress conditions at each pressure point, and pressure changes in the surrounding soil. The control decision-making and instruction generation module compares and analyzes the calculation results of the data processing and analysis module with preset construction parameters and standards. If the caisson deviates or the settlement rate is abnormal, the control decision-making module automatically generates control instructions, such as adjusting the jack's downward pressure, changing the soil extraction position and speed, and controlling the grouting volume of the mud drag reduction system. The data analysis and decision-making module uses professional data analysis software to analyze collected data in real time, calculating the caisson's settlement, inclination, the stress conditions at each pressure point, and pressure changes in the surrounding soil.

[0059] ③ Execution and Feedback Adjustment: Upon receiving the control command, the execution control module immediately controls the corresponding equipment to execute the operation. Simultaneously, sensors continuously monitor the construction status and feed new data back to the data processing module, forming a closed-loop control system to ensure that the construction process is always under precise control.

[0060] The above construction methods include:

[0061] Step S1, construction of the anchor pile 15 (i.e., construction of the cast-in-place pile (anchor)):

[0062] like Figure 2 As shown, according to design requirements, cast-in-place pile equipment was used for construction, ensuring that pile length, diameter, and verticality met standards. Construction was carried out along the designed radius, centered around the caisson. After the cast-in-place piles reached full strength, the floating piles were chiseled out to a set distance below the ground, exposing the rebar, and then the reinforced concrete ring beam was cast. During the ring beam casting, an automatic control system precisely positioned the embedded parts required for the installation of the supporting device for the submersion jack 17, ensuring accurate positioning and secure fixation.

[0063] Step S2: Isolation Pile Construction; SMW Method Isolation Pile Construction: The isolation piles are constructed using the SMW method. The specifications and models of the triaxial mixing piles and inserted steel sections are determined according to the design. The steel section pile length exceeds the bottom of the caisson blade foot. During construction, an automatic control system strictly controls parameters such as the cement content, water-cement ratio, sinking and lifting speeds of the triaxial mixing piles to ensure pile quality. The system also monitors the verticality, length, top elevation, and displacement of the steel sections to ensure that the steel sections meet construction requirements. During construction, the sinking speed, lifting speed, and mixing frequency of the mixing piles are strictly controlled to ensure uniform mixing of the cement and soil. Core sampling is regularly conducted to test the strength of the mixing piles to ensure pile quality. Incoming steel sections are quality inspected to ensure compliance with design requirements. During steel section welding, welding specifications are strictly followed to ensure weld quality. Some time after the completion of the mixing pile construction, the steel sections are inserted using specialized equipment. The verticality, length, and top elevation of the steel sections are controlled to ensure compliance with allowable tolerances.

[0064] Step S3, caisson construction: measurement and layout, foundation pit excavation, laying of sand cushion layer 2, laying of concrete cushion layer 5, brick formwork construction, scaffolding erection, caisson production; specifically, as Figures 3-5 The caisson construction includes the following steps:

[0065] ① Surveying and setting out: Before construction, high-precision surveying instruments are used to perform high-precision surveying and positioning based on the coordinates and reference points on the design drawings, utilizing an automated control system. Coordinate control points and temporary leveling points are arranged around the jacking well, outside the construction area, and are regularly inspected and re-measured by the system. Gantry piles are set around the jacking well, and lime powder is used to mark the well's center axis and foundation pit outline, which serve as a basis for caisson construction and sinking positioning.

[0066] ② Foundation pit excavation: A combination of mechanical excavation and manual finishing is used. During excavation and slope excavation, concrete surfacing is used to ensure slope stability and proper drainage. Mechanical excavation with a backhoe is performed to a certain elevation above the pit bottom. Manual sloping and leveling are then performed to avoid disturbing the underlying soil layer. A gravel blind ditch and a water collection well are installed at the bottom of the caisson pit to promptly drain accumulated water, remove loose mud, and maintain a smooth and dry bottom. An automatic control system monitors the excavation depth and slope stability in real time to ensure construction safety.

[0067] ③ Laying Sand Cushion Layer 2: After the foundation pit excavation passes acceptance, lay the medium-coarse sand cushion layer 2 promptly. Lay the sand cushion layer 2 in layers, sprinkling water and compacting it with a vibrating plate. Control the moisture content and dry bulk density of the sand cushion layer 2 to achieve a medium density. Before laying the second layer, the system automatically checks whether the lower layer meets the requirements. During construction, the system controls continuous water pumping, and it is strictly forbidden for the sand cushion layer 2 to be immersed in water.

[0068] ④ Laying Concrete Pad 5: To expand the supporting area of the caisson blade foot, lay a layer of concrete pad 5 on top of the sand pad 2 and below the bottom beam and blade foot, ensuring the pad's flatness and thickness. After the sand pad 2 is laid and passes the dry bulk density test, the concrete pad 5 is leveled using a system and smoothed to serve as the base formwork for the bottom beam and blade foot.

[0069] ⑤ Construction of the Brick Formwork 4: After the concrete cushion layer 5 on the sand cushion layer 2 reaches a certain strength, the automatic control system accurately measures and positions the caisson plane. Construction of the brick formwork 4 begins, ensuring a smooth bevel on the blade foot. A low-grade cement mortar is used for brickwork, ensuring a smooth bevel on the blade foot. The brick formwork 4 is then whitewashed with a mixture of lime and a small amount of cement. To ensure the stability of the brick formwork 4, a template 8 is added to the outside of the brick formwork 4. Tie rods are used for tensioning. Holes for the tie rod screws on the caisson wall template 8 are reserved in the brick formwork 4.

[0070] ⑥ Scaffolding Erection: During the construction of the first section of caisson 1, scaffolding is erected as required, paying attention to the distance between the scaffolding and the shaft wall. The inner and outer scaffolding 6 and 7 are erected directly on the sand cushion 2, with wooden planks placed under the lower ends of the vertical pipes, and the scaffolding separated from the shaft wall. During the caisson sinking process, the inner and outer scaffolding are removed. During the caisson heightening process (for example, after the first section of caisson 1 has been sunk and the second section caisson 10 is being heightened), the outer scaffolding 7 remains on the ground, while the inner scaffolding 6 utilizes pre-embedded components in the shaft wall, adopting a cantilevered scaffolding design. The system monitors the scaffolding's erection parameters and safety in real time and provides early warnings.

[0071] Caisson Fabrication: Caisson construction involves conventional methods for steel reinforcement, formwork 8, and concrete. Caissons are prefabricated in multiple stages, each of which can be poured in one go or in two stages using a pump truck 9. Figure 10 shows the second section of the caisson. The system monitors the concrete pouring process to ensure quality.

[0072] Step S4, sinking the caisson;

[0073] Specifically, such as Figure 2 、 6 As shown in Figures 1 to 8, step S4 specifically includes:

[0074] ① Pre-sinking Preparation: After the caisson concrete reaches the design strength, the blade foot concrete cushion layer 5 and brick formwork are removed symmetrically, starting from the inside and then moving outwards. Broken bricks and other debris are removed from the caisson. Measurement marks are marked on the caisson walls, and a horizontal indicator is set up to monitor the caisson's sinking progress. The blade foot formwork 8 is removed when the concrete strength reaches 70%. The first section of the caisson (1) must reach 100% of the design strength before sinking. The concrete strength of each subsequent section must not fall below 70%. An automatic control system monitors the concrete strength in real time and automatically prompts the user to proceed to the next step when the required strength is met.

[0075] ② Installation of pressure sinking equipment: Figure 2 As shown, eight sinking points are set in the form of an annular concrete pedestal, steel strands, and steel corbels 16 welded to the outer shaft wall. According to the deviation of the caisson, the automatic control system flexibly adjusts the downward pressure of the eight different sinking points, which assists the sinking and correction of the caisson. Steel corbels 16 are installed on the upper part of each section of the shaft wall. The steel corbels 16 are made of a double-piece steel combination. At the same time, reinforced steel plates are set at the junction position and the lower diagonal rod position to enhance the overall rigidity. The jack 17 (the jack 17 is a through-hole jack), steel strands, and hydraulic system are installed, and the system is used to debug the equipment to ensure that each device is firmly connected and that the equipment operates normally. After the installation is completed, the equipment is debugged and the pressure, stroke, synchronization and other parameters of the equipment are checked to ensure that the construction requirements are met.

[0076] ③ Soil extraction and downward pressure: Based on the measured data of the height difference and inclination of the caisson during initial sinking, the automatic control system precisely controls the pressure of the jack 17 at the sinking point to correct the caisson's deviation. Correction can be performed at a single point or multiple points. The principle of caisson sinking is "pressure first, then soil extraction." The jack 17 is activated and begins to slowly apply pressure to the caisson. When the pressure reaches a predetermined value and the caisson cannot be sunk, soil extraction begins. During construction, the steel strand is passed through the through-hole jack 17 and then anchored to the upper end of the jack 17 cylinder using a matching tool anchor plate and tool clip. When downward pressure is required, the jack 17 cylinder extends upward to support the tool anchor plate. Once the steel strand is tightened, the jack 17 applies downward pressure to the steel bracket 16 fixed to the caisson. This pressure is transmitted from the steel bracket 16 to the caisson position, causing the caisson to sink. The caisson can be sunk using a jack 17. Each time the jack 17 is lifted, the system automatically adjusts the working clamps and proceeds with the next sunk operation until the caisson is lowered to the designed elevation. During the earth-excavation process, an automatic control system monitors the caisson's elevation and tilt in real time. Based on the measured data, the pressure of the jacks 17 at each sinking point is adjusted, allowing for single-point or multi-point corrections to ensure even sinking of the caisson. The caisson is sunk using drainage. A crawler crane 11 equipped with a grab bucket 12 can be used to excavate soil from the center of the caisson outwards, forming a pot bottom for even sinking and preventing sudden sinking. The system monitors the excavation process and the caisson's sinking status in real time.

[0077] ④ Mud Drag Reduction: Based on the site conditions, the slurry tank, slurry mixer, grouting pump, and slurry delivery pipeline are arranged using an automatic control system. Slurry is prepared according to strict slurry ratios, controlling parameters such as specific gravity, viscosity, colloid content, and pH. During the grouting process, the injection pressure and sequence are controlled, and slurry is continuously replenished as the caisson sinks to ensure effective drag reduction. After the caisson is lowered, slurry is promptly replaced to ensure the stability of the surrounding soil. Grouting is performed using a grouting pump with a slightly higher pressure at startup. Grouting is performed hole by hole, with continuous replenishment as the caisson sinks to ensure the slurry surface remains above ground level. After the caisson is lowered, grouting is performed using the original grouting pipelines to replace the bentonite slurry. Ordinary Portland cement is used as the cement slurry. The system monitors various mud parameters and the grouting process in real time to ensure effective drag reduction.

[0078] ⑤ Caisson Bottom Sealing: After the caisson is sunk to the measured elevation, soil is continued to be removed from the caisson using a grab bucket 12 or other soil-extraction equipment until it reaches the designed elevation, leaving a certain thickness of soil plug. After the caisson is lowered into position, continuous observation is conducted, and the amount of subsidence is monitored using a total station. If the amount of subsidence is less than the set value, the system determines that the bottom sealing can be carried out. The caisson adopts a dry bottom sealing method, with symmetrical bottom sealing in sections. A thick crushed stone cushion is installed at the bottom of the caisson as a groundwater filtration layer. Cross beams are installed according to the design requirements to divide the bottom of the caisson into four compartments. Each compartment is equipped with a water collection well 3 near the center of the well. A hole is opened in the top plate of the water collection well 3, and a steel pipe is welded to it. A flange joint is formed on the top of the steel pipe. A pit is reserved in the bottom plate of the vortex pool at the joint. After the bottom plate concrete reaches the designed strength, it is sealed with a flange. Micro-expansive concrete is then poured. The cushion layer is poured symmetrically according to the compartments, and attention is paid to vibrating and compacting to ensure the flatness and strength of the cushion layer. During the concrete pouring process, the monitoring of the foundation pit is strengthened, including the observation of the settlement of the cyclone body and the monitoring of the surrounding environment, while ensuring the normal drainage of the water collection well 3 until the pouring of the cyclone bottom plate 13 is completed and reaches the design strength. 14 in the figure is the cyclone table. Each water collection well 3 is equipped with two sewage submersible pumps, one for backup and one for use, with a float control to automatically discharge the accumulated water in the well out of the well in time. At the same time, the system strengthens the monitoring of the foundation pit and the drainage of the pit bottom, including the observation of the settlement of the cyclone body at least once a day, and the monitoring of the surrounding environment of the cyclone pool at least twice a day, until the pouring of the cyclone bottom plate is completed and reaches the design strength. Specific application cases

[0079] Project Example 1: Baosteel Co., Ltd. Bar Steel Plant Product Structure Optimization and Reconstruction Project

[0080] 1. Project Overview: The cyclone pool is located within the construction site of the Baosteel Bar Steel Plant Product Structure Optimization and Renovation Project. It is bordered by Chuwu Road to the north, Chuer Road to the south, the proposed new main rolling bay to the east, and the control room of the newly built No. 2 gas booster station to the west. The cyclone pool utilizes a circular structure with an underground reinforced concrete deep foundation, consisting of an inner and outer cylinder. The ground elevation is -0.5m, the top elevation of the floor plate is -16.00m, and the top elevation of the shaft wall is +0.500m. The outer wall of the cyclone pool is 4m from the column foundation of the new main plant A / 207 line, 8.5m from the high and low voltage distribution room of the newly built No. 2 gas booster station, and 30m from the gas booster station support foundation. The outer cylinder of the cyclone pool is designed as a caisson with a wall thickness of 1m, an outer diameter of 16m, an inner diameter of 14m, a caisson height of 22.5m, a relative elevation of -0.500m to the ground (absolute elevation +4.200m), and a caisson top elevation of +0.500m.

[0081] 2. Construction Process: Following the technical solutions outlined in the aforementioned invention, the following steps were followed: automatic control system, cast-in-place pile anchoring, SMW isolation pile construction, caisson prefabrication, caisson pressure sinking, and caisson bottom sealing. Throughout the construction process, relevant quality control standards and safety measures were strictly adhered to to ensure quality and safety.

[0082] Data collection: Displacement sensors, tilt sensors, soil pressure sensors and other equipment are installed at key locations of the caisson, such as the blade foot, the shaft wall, as well as the foundations of surrounding buildings and soil. These sensors collect real-time data on the caisson's settlement, inclination, displacement changes, as well as soil displacement and building settlement in the surrounding environment.

[0083] Data Analysis and Decision-Making: Collected data is transmitted via wired or wireless channels to the data processing and analysis module. This module uses pre-set algorithms and models to conduct in-depth analysis, calculating parameters such as settlement rate and tilt rate, comparing them to standard values, and issuing warnings if they exceed the standards. The control decision-making and command generation module automatically generates control commands based on the data analysis results. For example, if a caisson tilts, the system calculates the jack pressure adjustment value based on the tilt and generates the corresponding command.

[0084] ③ Execution and feedback adjustment: After receiving control commands, the execution control module accurately operates jacks, earth-moving equipment, grouting equipment, etc. For example, the hydraulic system adjusts the jack pressure, controls the earth-moving position and speed of the earth-moving equipment, and controls the pressure and grouting volume of the grouting equipment according to the commands.

[0085] Ground anchor construction: Eight sets of φ800 bored piles were used as anchor piles, connected by a circular reinforced concrete cap. Piles were constructed along a 9.5m radius, centered around the caisson, with a length of 60m. The anchors were maintained at a distance of 0.5-1.5m (edge-to-edge) from the caisson. After the piles were poured and reached full strength, the floating piles were chiseled out to 0.8m below ground level, exposing the rebar. A reinforced concrete ring beam was then cast. The ring beam was 0.8m deep and 1.6m wide, with a concrete strength grade of C35. During pouring, the embedded components required for the installation of the supporting device for the submersion jack were placed.

[0086] SMW method isolation pile construction:

[0087] North Side: Because the high and low voltage distribution rooms of the No. 2 gas booster station are located on a natural foundation prone to differential settlement, isolation piles were installed on the north side. SMW piles were used, with triaxial mixing piles of φ850@600 mm and inserted with H700x300x13x24 steel sections. The length of the steel piles exceeded the bottom of the caisson blade by 1.5 m.

[0088] South Side: After the pile foundation construction of the south powerhouse is completed, core filling will be carried out, and the pile foundation cap and coupling beam within the affected area will be poured. Isolation piles will be installed adjacent to the pile foundation, also using the SMW method. The triaxial mixing piles and inserted steel specifications are the same as those for the north side.

[0089] Construction Technical Requirements: Triaxial mixing piles utilize PO 42.5 grade ordinary Portland cement at a cement content of 20% (increased to 25% in special areas), a water-cement ratio of 1.5, a wall permeability coefficient of 10-6 to 10-7 cm / s, and a 28-day unconfined compressive strength standard value of no less than 0.8 MPa. During construction, a mixer head with low soil displacement should be used. Parameters should be adjusted through trial pile construction. The sleeve-in-one-hole method should be employed. Either a one-shot-one-mix or two-shot-two-mix process should be selected based on geological conditions. The sinking and lifting speeds should be controlled to ensure uniform cement mixing. Pile strength should be determined through core sampling. The number, location, and test block preparation of cores should be carried out in accordance with regulations. After core sampling, the voids should be filled with grouting. Pile verticality deviation should not exceed 1 / 200, pile position deviation should not exceed 50 mm, and the pile base elevation and diameter deviations should meet requirements. Steel sections should be whole, at least 80% new, and welded according to specifications, with weld quality grade no lower than Grade 2. A single steel section should have no more than two welded joints, avoiding locations subject to significant stress. Adjacent steel section joints should be vertically staggered by at least 1 meter. Inserted steel sections should be anchored into the capping ring beam. Straightness and weld quality should be inspected before insertion. Insertion should be completed within 30 minutes of the completion of pile mixing. If steel sections need to be removed, drag reduction measures should be implemented beforehand. After removal, fill the gaps with grouting, ensuring that all tolerances for steel section insertion meet specified requirements.

[0090] Caisson prefabrication:

[0091] Surveying and setting out: Based on the coordinates on the design drawings and the benchmarks provided by Party A, coordinate control points and temporary leveling points are arranged around the pipe jacking shaft and outside the construction impact area with an accuracy of ±1mm. A measurement verification form is completed and approved by Party A and the supervisor. During construction, it is protected and regularly inspected and re-measured. Gantry piles are set around the pipe jacking shaft, and the shaft center axis and foundation pit outline are marked.

[0092] Excavation of the foundation pit: A combination of mechanical excavation and manual finishing was used. Concrete was used for slope excavation, drainage was ensured, and the excavation elevation was controlled. Manual slopes were cut and the bottom leveled approximately 20 cm from the pit bottom. A 0.3 x 0.3 m gravel blind ditch and a water collection well were installed at the bottom of the foundation pit to remove loose mud and maintain a smooth and dry surface.

[0093] Laying the Sand Cushion: After the foundation pit passes inspection, promptly lay a 1500mm thick medium-coarse sand cushion layer, layered 30cm apart. Use a flat plate to vibrate the sand at a moisture content of 15% to achieve a medium density with a dry bulk density of no less than 1.56t / m³. Before paving, establish a blind ditch at the bottom of the foundation pit for drainage. Pump water continuously during construction to prevent the sand cushion from soaking.

[0094] Laying the concrete cushion layer: On the sand cushion layer, lay a 20cm thick C25 plain concrete cushion layer under the bottom beam and blade foot. The width of the plain concrete cushion layer of the blade foot and bottom beam is 20cm outside the well wall. Ensure that it is level with an error of less than 5mm. Smooth the surface as a bottom formwork.

[0095] Blade foot construction: After the plain concrete cushion layer reaches a certain strength, the plane position of the caisson is accurately measured and placed on the cushion layer. Low-grade cement mortar is used to lay brick formwork to ensure that the inclined surface of the blade foot is smooth. It is painted with lime and a small amount of cement mixture, and a template is added on the outside. M12@450 tie rods are used for tensioning, and the screw holes for the tie rods of the well wall template are reserved.

[0096] Scaffolding: When constructing the first section of the caisson, the inner and outer scaffolding are set on a sand cushion. Wooden boards are placed at the bottom of the vertical pipes, and they are separated from the caisson wall by 30cm. They are removed when the caisson is sunk. When the caisson is raised, the outer scaffolding is set on the ground, and the inner scaffolding is cantilevered and installed through the embedded parts in the caisson wall.

[0097] Caisson production: Steel bars, formwork and concrete are constructed according to conventional methods. The caisson is prefabricated in two steps. The first step is 9m high (cast in one go), and the second step is 13.5m high (cast in two steps).

[0098] Caisson sinking:

[0099] Pre-sinking preparations: Chisel away the plain concrete cushion and brick formwork for the blade foot, working symmetrically from the inside out to the outside. Clean away broken bricks from the well. Mark the dimensions and set a level indicator on the well wall. Remove the blade foot formwork when the concrete strength reaches 70%. The concrete strength of the caisson should reach 100% of its design strength when the first section is sunk. The concrete strength of each subsequent section should be no less than 70% when sinking.

[0100] Installation of the subsidence equipment: A circular concrete cap, steel strands, and welded steel brackets were used on the outer shaft wall. Eight subsidence points were set. A steel bracket made of double-jointed steel sections was installed on the upper portion of each shaft wall. The upper crossbar and diagonal bars were constructed of HM500x300x11x18 steel. Reinforced steel plates were installed at the junction and lower diagonal bars to enhance rigidity. Jacks, steel strands, and the hydraulic system were installed and commissioned.

[0101] Soil extraction and pressure reduction: Based on initial sinking measurement data, jack pressure correction is applied at the sinking point, either single or multiple points. Following the principle of "pressure first, soil extraction later," pressure is applied by the jack. When the jack reaches a predetermined value and the caisson cannot be lowered, soil is extracted from the caisson. Steel strands are threaded through through-hole jacks and anchored to the upper end of the oil cylinder. As the jacks are lifted, the steel brackets exert downward pressure on the caisson, forcing it to sink. The jacks have an effective stroke of 18 cm. After each lift, the working clamps are adjusted, and this process is repeated until the caisson reaches the designed elevation. The caisson is lowered using drainage. A 50-ton crawler crane equipped with a 0.75-meter grab bucket excavates soil from the center of the caisson outward, forming a pot-shaped bottom for even sinking and preventing sudden subsidence.

[0102] Mud Drag Reduction: To address the low sinking coefficient in the later stages of caisson sinking, a thixotropic slurry system is employed to assist sinking. A slurry tank, slurry mixer, grouting pump, and slurry delivery pipeline are deployed. Three grouting pipes are installed every four meters above the variable cross-section, controlled by six 1-inch PPR main pipes. Horizontal grouting pipes are spaced 1500mm apart. The slurry is prepared using a weight ratio of high-quality bentonite, soda ash, and water in a 4:1:1:15 ratio. Adjustments are made to the soil properties, and mud specifications are strictly controlled. Grouting is performed using a grouting pump, controlling the pressure, and injecting slurry hole by hole. As the caisson sinks, the slurry level is maintained approximately 0.3m above the ground. After the caisson is lowered, the bentonite slurry is replaced with grouting from the original grouting pipeline. Ordinary Portland cement is used as the cement slurry, with a water-cement ratio not exceeding 0.45 to ensure adequate fluidity.

[0103] Caisson Bottom Sealing: After the caisson is sunk to the designed elevation, soil is removed from the caisson to a depth of -18.3m (500mm below the top of the cross beam), leaving a 3.7m thick soil plug. After sinking to its full height, continuous observation is conducted for 8 hours. If the sinking amount is less than 10mm, dry sealing is performed, carried out symmetrically in sections. A 300mm thick crushed stone cushion is installed at the bottom of the caisson as a filtration layer. The cross beams divide the caisson into four compartments, each with a 1m×1m×1m water collection well near the center. The caisson walls and roof are constructed of 10mm thick steel plates reinforced with ∠50×5mm angle steel. Filter holes of 20x100 mm are opened in the side panels around the caisson, and a 300mm thick crushed stone bottom is laid. A 1.5m DN150 steel pipe (L) is welded to the top of the water collection well, with a flange connection at the top. A pit is reserved for the swirl pool floor. After the concrete floor reaches the designed strength, it is sealed with a flange and poured with C35 slightly expansive concrete. Each water collection well is equipped with two 60m head submersible sewage pumps, one in standby mode and one in use, controlled by a float. A C15 plain concrete cushion is poured on top of the gravel cushion at the well bottom, symmetrically according to the location of the silo. Foundation pit monitoring and bottom drainage are strengthened until the cyclone basin floor is poured and reaches its design strength.

[0104] 3. Construction effect: By adopting the push-in construction technology with automatic control system, the safety of surrounding buildings is ensured, the settlement of monitored buildings is controlled at the millimeter level, the cost of measures is reduced, the construction period is shortened, and the foundation is laid for the project to be put into production on schedule. The advanced nature of this construction technology has been unanimously recognized by the owner, supervisor and peers.

[0105] (II) Project Example 2: Dazhou Iron and Steel Group Co., Ltd., Sichuan Province Dazhou Iron and Steel Relocation and Upgrading Project

[0106] 1. Project Overview: The cyclone pool is located within the construction site of the Dagang Relocation and Upgrading Project - Rolling Unit - Bar Section. It is adjacent to the secondary office building under construction to the north, the main rolling mill building under construction to the south, the main electrical room of U-Te Steel to the east, and the proposed fan room and chimney to the west. The cyclone pool adopts a circular structure with an underground reinforced concrete deep foundation, consisting of an inner and outer cylinder. The ground elevation is -0.300m, the top elevation of the base plate is -22.200m, and the top elevation of the shaft wall is +0.000m. The outer wall of the cyclone pool is 4m from the column foundation of the new main plant H / 2 line, 40m from the new secondary office building, 16m from the fan room and chimney foundations, and 9m from the main electrical room of U-Te Steel. The outer cylinder of the cyclone pool is designed as a caisson with a wall thickness of 1m, an outer diameter of 19m, an inner diameter of 17m, a caisson height of 24.5m, a relative elevation of -0.500m to the ground (absolute elevation +376.300m), and a caisson top elevation of +0.000m.

[0107] 2. Construction process: As with the Baosteel project, construction was carried out strictly in accordance with the technical solution in the invention content to ensure that each construction link met the requirements.

[0108] 3. Construction Results: This method ensured the safety of surrounding buildings, reduced construction costs, and shortened the construction period. The advanced nature of this construction technology was unanimously recognized by the owner, supervisor, and peers.

[0109] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any other form. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes for application in other fields. However, any simple modification, equivalent change and modification of the above embodiment made according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

[0110] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0111] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0112] The present invention and its embodiments are described above. This description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs structures and embodiments similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A method for constructing a press-in caisson based on an automatic control system, characterized in that: The automatic control system includes a data acquisition module, a data analysis and decision module and an execution control module; The data acquisition module is used to collect data in real time during the sinking process of the caisson, the data analysis and decision module analyzes the collected data in real time and generates control instructions, and the execution control module regulates the sinking equipment and the soil sampling equipment according to the control instructions; The construction method comprises: Step S1, ground anchor pile construction: using cast-in-place piles as ground anchor piles; Step S2, isolation pile construction; Step S3, caisson construction: measurement and layout, foundation pit excavation, laying of sand cushion layer, laying of concrete cushion layer, brick formwork construction, scaffolding erection, and caisson fabrication; Step S4, sinking the caisson: Specifically, step S4 includes: Preparation before sinking: Before sinking, the concrete cushion and brick formwork at the caisson foot are removed, measurement marks are drawn on the walls around the caisson, and a horizontal indicator is set up. The automatic control system monitors the concrete strength in real time and automatically prompts the user to proceed to the next step when the preset requirements are met. Installation of the caisson equipment: Steel brackets are welded at intervals on the outer wall of the caisson, and a jack is installed on each steel bracket. The jack is connected to the anchor pile through a steel strand, and the jack is connected to the automatic control system through a hydraulic system; Soil excavation and downward pressure: The automatic control system controls the pressure of the jack at the sinking point based on the measured data of the height difference and inclination of the caisson during initial sinking, and corrects the sinking of the caisson. The automatic control system monitors the excavation process and the sinking status of the caisson in real time; Step S5, sealing the bottom of the caisson: Specifically, in step S5: after the caisson is sunk to the designed elevation, soil is continuously taken from the caisson, and a soil plug 3.5 to 3.9 meters thick is retained; and after sinking into place, a predetermined time is continuously observed, and the bottom is sealed when the sinking amount is less than 10 mm.

2. The method for constructing a press-in caisson based on an automatic control system according to claim 1, wherein: The step S4 also includes the step of arranging a mud box, a slurry mixer, a slurry pump and a slurry delivery pipeline to reduce mud resistance during the caisson sinking process.

3. The method for constructing a press-in caisson based on an automatic control system according to claim 2, wherein: During the mud drag reduction step, the mud density is controlled between 1.10 and 1.

3.

4. The method for constructing a press-in caisson based on an automatic control system according to claim 2, wherein: In the step of taking soil and pressing down, the principle of sinking the caisson is to press first and then take soil. The jack starts to apply pressure to the caisson. When the jacking force of the jack reaches the predetermined value, soil is taken from the well. The caisson is sunk by drainage, and a crawler crane equipped with a grab bucket is used to dig soil from the center of the caisson to the surrounding areas to make the caisson sink evenly.

5. The method for constructing a press-in caisson based on an automatic control system according to claim 1, wherein: The data analysis and decision-making module includes a data processing and analysis module and a control decision and instruction generation module. The data processing and analysis module performs real-time analysis on the collected data, calculates the settlement amount, inclination, stress conditions of each subsidence point and pressure changes of the surrounding soil of the caisson; the control decision and instruction generation module compares and analyzes the calculation results of the data processing module with the preset construction parameters and standards and automatically generates control instructions.

6. The method for constructing a press-in caisson based on an automatic control system according to claim 1, wherein: The data acquisition module includes: structural safety monitoring sensors, construction process monitoring sensors, special process monitoring sensors and environment monitoring sensors.

7. The method for constructing a press-in caisson based on an automatic control system according to claim 6, wherein: The structural safety monitoring sensors include tilt sensors, settlement sensors, earth pressure sensors, displacement sensors, vibration sensors and strain sensors; The construction process monitoring sensors include laser ranging sensors; temperature and humidity sensors, pressure sensors, flow sensors, density sensors, pH sensors, ultrasonic sensors and infrared temperature sensors; The special process monitoring sensors include verticality sensors, torque sensors, acoustic emission sensors, laser scanning sensors and fiber grating sensors; The environmental monitoring sensors include pore water pressure gauges, groundwater level gauges, wind speed sensors and Video surveillance camera.

8. The method for constructing a press-in caisson based on an automatic control system according to claim 7, wherein: During the caisson construction process, the soil pressure sensors and displacement sensors are buried around and at the bottom of the caisson according to design requirements, and the pressure sensors and displacement sensors are installed on the jacks and steel strands.

9. The method for constructing a press-in caisson based on an automatic control system according to claim 1, wherein: The step S3 specifically includes: Step S31, surveying and setting out: Before construction, an automatic control system is used to measure and position the caisson, and coordinate control points and temporary leveling points are arranged around the caisson. The automatic control system is used to regularly check and re-measure, gantry piles are set around the caisson, and the center axis of the caisson and the foundation pit outline are marked with lime powder; Step S32, excavation of the foundation pit: when the soil is excavated to an elevation of 19 to 21 cm from the pit bottom, artificial slope repair and bottom leveling are performed, a gravel blind ditch and a water collection well are set at the bottom of the caisson foundation pit, and an automatic control system monitors the excavation depth and slope stability in real time; Step S33, laying the sand cushion layer: after the foundation pit excavation is qualified, the medium-coarse sand cushion layer is laid and laid in layers, while sprinkling water and vibrating to compact it. Before laying the next two layers, the lower layer is automatically checked to see if it meets the requirements; Step S34, laying a concrete cushion layer: laying a concrete cushion layer on the sand cushion layer, under the bottom beam and the blade foot; Step S35, brick formwork construction: after the concrete cushion layer on the sand cushion layer reaches a preset strength, the caisson plane position is measured and placed by the automatic control system, and brick formwork construction is carried out; Step S36, scaffolding erection: When the first section of the caisson is being constructed, the inner and outer scaffolding are erected directly on the sand cushion layer; during the sinking of the caisson, the inner and outer scaffolding are dismantled. During the heightening of the caisson, the outer scaffolding is still erected on the ground, and the inner scaffolding adopts a cantilever scaffolding; Step S37, caisson construction: the caisson is constructed in multiple times.

10. The method for constructing a press-in caisson based on an automatic control system according to claim 1, wherein: In step S4, the brick formwork is removed when the concrete strength of the caisson reaches 70%, the concrete strength of the caisson reaches 100% of the design strength when the first section sinks, and the concrete strength of the remaining sections is not less than 70% when they sink.

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