Floating pouring test device and method for reinforced concrete immersed tube tunnel

Abstract

The invention belongs to the technical field of immersed tunnels, and particularly discloses a reinforced concrete immersed tunnel floating state pouring test device and method, and the device comprises a test pool, a pipe joint mooring model, a floating state pouring model and a monitoring instrument. The test pool simulates the actual water area environment, and the pipe joint mooring model is composed of an immersed tunnel model, a wharf model and a mooring rope and simulates the rigidity characteristic and dynamic response of a mooring system; the floating state pouring model comprises a crane, a pouring funnel and a pouring template, the pouring funnel is filled with model mulling sand, and the bottom of the pouring funnel is open and connected with the valve control system so as to adjust the falling speed of the model mulling sand; the monitoring instrument comprises a cable dynamometer and a six-degree-of-freedom monitor and is used for acquiring mooring force and pipe joint motion parameters in real time. The device can accurately simulate the floating pouring process of the immersed tunnel, provides data support for a floating pouring scheme, has remarkable beneficial effects, and can be widely applied to simulation of the floating pouring process of the immersed tunnel and other water floating bodies.

Description

Technical Field

[0001] The present invention relates to the technical field of immersed tube tunnels, and particularly to an experimental device and method for floating-state casting of a reinforced concrete immersed tube tunnel. Background Art

[0002] An immersed tube tunnel is a construction method for building a tunnel underwater. Its construction process usually includes prefabricating tube segments in a dry dock or on a shipyard, then sliding the tube segments into the water to make them float, and towing them to the designed tunnel location and sinking them into a pre-dug underwater trench. During the construction of an immersed tube tunnel, wave and current loads will have an important impact on the construction cost, safety, and service life of the tunnel project. Especially in some projects, due to the navigation condition restrictions in the construction area, the casting of the pipe section needs to be carried out in stages, that is, the first-stage casting is carried out in the dock, and the second-stage casting is carried out after towing to the mooring operation near the construction area. In the second-stage casting, the top plate compartment also needs to be cast multiple times.

[0003] Currently, most of the domestic and foreign research and engineering examples focus on prefabricating and casting the immersed tube in the dock and then towing it to the construction water area for sinking. For example, the immersed tube tunnel of the Hong Kong-Zhuhai-Macao Bridge adopts segmental pipe section prefabrication. By using integral casting, the number of casting times of the pipe section is reduced, the amount of concrete cast at one time is increased, the horizontal construction joint of the concrete is cancelled, and the anti-seepage performance of the pipe section itself is improved. However, there is currently no relevant research on the floating-state casting of reinforced concrete immersed tube pipe sections. Summary of the Invention

[0004] The purpose of the present invention is to provide an experimental device and method for floating-state casting of a reinforced concrete immersed tube tunnel to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above purpose, in one aspect, the present invention proposes an experimental device for floating-state casting of a reinforced concrete immersed tube tunnel, including:

[0006] An experimental water tank for simulating the actual water environment;

[0007] A pipe section mooring model, including an immersed tube tunnel model, a wharf model, and cables. The immersed tube tunnel model and the wharf model are respectively placed in the experimental water tank, and the bottom of the immersed tube tunnel model is connected to the cables to simulate the stiffness characteristics and dynamic response of the actual mooring system;

[0008] A floating-state casting model, including a crane, a casting funnel, and a casting formwork. The casting funnel is filled with model sand inside, and the bottom is open and connected to a valve control system to adjust the falling speed of the model sand;

[0009] Monitoring instruments, including a cable force meter and a six-degree-of-freedom monitor, are installed on the pipe section and the cables for real-time acquisition of mooring forces and pipe section motion parameters.

[0010] Further, a flow and wave generating device is arranged in the test water tank, including a blower, a wave generator and a water pump, for generating set environmental conditions.

[0011] Further, the model mixed sand is composed of sand grains with different particle sizes and densities mixed in proportion, so that its unit weight is consistent with that of the prototype concrete.

[0012] Further, the model mixed sand is obtained by mixing iron sand and quartz sand, and its density is 2.4 g / cm 3 .

[0013] Further, marking points are arranged at the center and corner positions of the immersed tube tunnel model to assist the monitoring instrument in obtaining the movement amount of the pipe section and the corner freeboard value.

[0014] Further, the six-degree-of-freedom monitor adopts a real-time high-speed six-dimensional dynamic tracking system and is equipped with a 2000 Hz high-speed infrared array camera.

[0015] Further, the floating state casting model further includes a casting formwork for being installed into the immersed tube tunnel model.

[0016] On the other hand, the present invention also provides a method for testing the floating state casting of a reinforced concrete immersed tube tunnel. Using the test device for floating state casting of a reinforced concrete immersed tube tunnel described in any one of the above, the method includes the following steps:

[0017] Step S1: Fabricate an immersed tube tunnel model, a wharf model and cables according to parameter design;

[0018] Step S2: Calibrate the input conditions of wind, wave and current;

[0019] Step S3: Install the casting formwork in the immersed tube tunnel model;

[0020] Step S4: Turn on the cable force meter and the six-degree-of-freedom monitor, turn on the input conditions of wind, wave and current, and wait for the input conditions to be stable;

[0021] Step S5: Open the bottom valve of the pouring funnel to make the model mixed sand evenly fall into the casting formwork;

[0022] Step S6: Turn off the input conditions of wind, wave and current, turn off the monitoring instrument, adjust the cable length, and conduct the pouring test in the next stage.

[0023] Further, in the step S2, the calibration of the input conditions of wind, wave and current includes the following steps:

[0024] Add water to the test water tank to the set test water level;

[0025] After the water surface in the test pool stabilizes, turn on the fan, measure the wind speed on the windward side of the pipe section through an anemometer, turn on the wave generator, measure the wave conditions in the river channel through a wave height meter, and turn on the water pump to measure the cross-sectional flow velocity of the river channel through a current meter.

[0026] Furthermore, during the pouring process, the movement amount and the corner freeboard value of the immersed tube tunnel model are monitored in real time, and the cable length and the pouring speed are adjusted according to the monitoring data to ensure the stability of the pipe section.

[0027] Compared with the prior art, the present invention discloses at least the following beneficial effects:

[0028] The present invention provides an experimental device and method for floating pouring of a reinforced concrete immersed tube tunnel. By simulating the wind, wave and flow conditions in a harbor basin, a wharf, an immersed tube tunnel and cables are made according to a ratio, and a crane control system and a high-precision funnel valve are equipped. Pouring is carried out with equal-density mixed sand instead of concrete, which can accurately simulate the floating pouring process. The experiment can obtain the movement displacement, attitude, acceleration, force change of the pipe section at different pouring stages, as well as the force change law of the cable, ensuring the experimental accuracy and providing data support for the floating pouring scheme. The invention can more accurately simulate the floating pouring process of the immersed tube tunnel and other floating bodies on water, and reasonably reflect the movement response of the immersed tube and the mooring force. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0030] Figure 1 It is a schematic plan structure diagram of the physical model of the immersed tube tunnel leaving the dock of the present invention;

[0031] Figure 2 It is a flow chart of the experimental method for the physical model of the immersed tube tunnel leaving the dock of the present invention;

[0032] In the figure: 1. Test pool; 2. Immersed tube tunnel model; 3. Wharf model; 4. Cable; 5. Crane; 6. Pouring funnel; 7. Valve control system; 8. Pouring formwork; 9. Model mixed sand. Detailed Embodiments

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] In the prior art, the casting of immersed tunnels is usually limited to be completed in the dry dock environment, making it difficult to simulate the influence of waves and water flow on the construction process under floating conditions. When staged casting is required in actual projects, there is a lack of effective means to evaluate the stability of the pipe section under dynamic loads, resulting in construction safety risks and precision control problems. Especially in areas with restricted navigation conditions, the hydrodynamic interference during the floating casting stage may cause the displacement of the pipe section to exceed the standard or structural damage, and the existing model test devices cannot accurately reproduce such complex working conditions.

[0035] To solve the above problems, aiming at the insufficient simulation of the floating casting environment, a pool test environment including the combined action of waves and water flow is considered to be constructed; aiming at the simulation requirements of staged construction, an adjustable mooring system is designed to adapt to different casting stages; aiming at the difficulty of dynamic response monitoring, a six-degree-of-freedom motion and cable force synchronous acquisition system is developed. Through the similarity design of the physical model and the construction process, the coupled simulation of environmental loads, construction operations and structural responses is realized.

[0036] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] Refer to Figure 1 As shown, an experimental device for floating casting of a reinforced concrete immersed tunnel according to an embodiment of the present invention includes an experimental pool 1, a pipe section mooring model, a floating casting model and monitoring instruments. The pipe section mooring model includes an immersed tunnel model 2, a wharf model 3 and a cable 4. The floating casting model includes a movable crane 5, a casting funnel 6 with a valve and a casting formwork 8. The monitoring instruments include a cable force meter and a six-degree-of-freedom monitor.

[0038] In the above embodiment, the experimental pool 1 refers to an enclosed water body used to simulate the actual water area environment, and a concrete structure can be used in combination with a wave maker and a water pump system to generate waves and water flow. Its function is to provide a controlled hydrodynamic load environment for the pipe section.

[0039] In the above embodiment, the pipe section mooring model is a constraint system composed of an immersed tunnel model 2, a wharf model 3 and a cable 4. A reinforced concrete structure scaled according to a similarity scale can be used to simulate the prototype pipe section, and the cable 4 is composed of a steel cable and a spring in combination. Its function is to reproduce the stiffness characteristics and dynamic responses of the actual mooring system.

[0040] In the above embodiments, the floating-state casting model is a movable concrete conveying device, which includes a crane 5, a casting funnel 6, a valve control system 7 and a casting module. The casting funnel 6 is filled with model sand 9, and the valve control system 7 is fixedly connected below the casting funnel 6. The crane 5 driven by a servo motor can be used in cooperation with electromagnetic valves to control the casting path and speed. Its function is to accurately simulate the spatial distribution and temporal characteristics of concrete during the construction process.

[0041] In the above embodiments, the monitoring instrument refers to the data acquisition equipment installed on the pipe section and the cable 4. Strain-type cable force sensors and optical motion capture systems can be used to obtain the mooring force and pipe section motion parameters in real time, and evaluate the stability of the casting process. Specifically, in this embodiment, the monitoring instrument includes a cable force meter and a six-degree-of-freedom monitor.

[0042] Specifically, a flow generating and wave generating device is arranged in the test pool 1 to generate set environmental conditions. The immersed tube model is moored to the dock model 3 through a spring-steel cable composite cable 4. During the casting stage, the crane 5 moves along a preset trajectory, and the falling speed of the model sand 9 is adjusted through the valve control system 7 to match the density and flow rate of the prototype concrete characteristics. The six-degree-of-freedom monitor continuously collects the motion data of the pipe section, and the cable force meter records the load changes of the mooring system. The casting formwork 8 is made of lightweight materials such as honeycomb aluminum plates to avoid additional mass interfering with the floating equilibrium of the pipe section.

[0043] In a specific embodiment, the flow generating and wave generating device includes a fan, a wave generator and a water pump. By adjusting the parameters of the fan, wave generator and water pump in the test pool 1, the environmental conditions in the model test are kept dynamically similar to the actual construction conditions.

[0044] In a specific embodiment, an anemometer, a wave height meter and a current meter are used to measure the wind speed, wave height and current speed simulated by the flow generating and wave generating device respectively, and the output power of the equipment is repeatedly adjusted until the set threshold is reached. This step is used to accurately reproduce the hydrodynamic interference environment in the construction area and provide a reliable load input basis for the subsequent casting test.

[0045] In a specific embodiment, the current meter adopts a StreamPro micro acoustic Doppler current profiler. When the StreamPro ADCP is moved from one side of the cross section to the other side, the cross-sectional current speed can be measured.

[0046] In a specific embodiment, the crane 5 is used as a lifting device to tow the casting funnel 6 and control the falling path of the model sand 9. Specifically, an orbital crane 5 with movable wheels installed at the bottom can be adopted, and a drive system with adjustable speed is equipped to achieve fixed-point displacement. This device can simulate the moving casting process of a concrete pump truck in actual construction and ensure the uniform distribution of the model sand 9 in the pipe section cabin.

[0047] In a specific embodiment, the model sand mixture 9 is a substitute material that simulates the physical properties of actual concrete. Specifically, sand grains with different particle sizes and densities can be mixed in proportion to make its bulk density consistent with that of the prototype concrete. For example, iron sand and quartz sand are used for proportioning to obtain the model sand mixture 9 with a density of 2.4 g / cm 3 . The model sand mixture 9 reduces the test cost on the premise of ensuring gravity similarity. At the same time, the falling speed can be adjusted through the valve control system 7 to achieve precise matching of the pouring rate.

[0048] In a specific embodiment, the six-degree-of-freedom monitor uses a real-time high-speed six-dimensional dynamic tracking system (NDI OPTOTRAK Certus), and this system is equipped with a high-speed infrared array camera with 2000 Hz.

[0049] Compared with the prior art, traditional model tests only focus on the static mooring in the towing or sinking stage. Through the combination of the adjustable cable 4 system and the dynamic pouring device, this solution realizes the full-process simulation of the floating-state pouring for the first time. Most existing devices use fixed pouring equipment and cannot reflect the influence of the movement of construction machinery on the stability of the pipe section, while the movable crane 5 system of this application can accurately reproduce the spatial operation characteristics of actual construction.

[0050] Through the above technical solutions, this application can accurately simulate the influence of concrete pouring on the stability of the pipe section under the coupled action of waves and water flow, reveal the evolution law of the mooring system load during the staged construction process, and provide data support for optimizing the construction sequence and mooring plan. The real-time monitoring data can warn of the risk of pipe section overturning, guide the on-site construction to adjust the pouring speed and the tension of the cable 4, and avoid the occurrence of structural damage accidents.

[0051] Referring to Figure 2 as shown, the embodiment of the present invention also provides a method for the floating-state pouring test of a reinforced concrete immersed tunnel, using the reinforced concrete immersed tunnel floating-state pouring test device described in the above embodiment. This test method includes the following steps:

[0052] S1. Fabricate the immersed tunnel model 2, the wharf model 3, and the cable 4 according to the parameter design;

[0053] S2. Calibrate the input conditions of wind, wave, and current;

[0054] S3. Install the pouring formwork 8 in the immersed tunnel model 2;

[0055] S4. Turn on the cable force meter and the six-degree-of-freedom monitor, turn on the input conditions of wind, wave, and current, and wait for the input conditions to be stable;

[0056] S5. Open the valve, and make the model sand mixture 9 uniformly fall into the pouring formwork 8 through the movable crane 5;

[0057] S6. Close the input conditions of wind, wave and current, turn off the monitoring instruments, adjust the length of cable 4, and conduct the next-stage pouring test.

[0058] Specifically, after the actual construction parameters are converted into model parameters through similarity criteria, the immersed tube tunnel model 2 and the wharf model 3 are fabricated proportionally. Cable 4 is arranged in the test pool 1 to connect the pipe section and the wharf, simulating the restraint effect of the mooring system. The wind, wave and current environment is generated by calibrated fans, wave makers and water pumps to form a stable hydrodynamic load field. After the monitoring instruments are started, the crane 5 moves along the preset path to control the model sand 9 to be injected into the formwork through the pouring funnel 6. After each stage of pouring is completed, the length of cable 4 is adjusted according to the monitoring data to conduct the next working condition test. Through staged loading and dynamic control of environmental conditions, the continuous operation characteristics of floating-state pouring construction are fully reproduced.

[0059] Compared with the prior art, traditional model tests mostly adopt static pouring simulation, which cannot reflect the coupling effect of environmental loads and pouring progress in actual construction. Existing methods usually ignore the dynamic adjustment process of the cable 4 system when evaluating the stability of the pipe section and lack the consideration of the concrete flow effect. This solution realizes the full dynamic simulation of the construction process by constructing a multi-factor coupling test environment and synchronously controlling the wind, wave and current loads and the pouring operation. The operation mode of adjusting the length of cable 4 in stages is more in line with the real-time optimization requirements of the mooring system in actual projects.

[0060] Through the above technical solution, this application effectively solves the stability problem of the pipe section caused by environmental interference during the floating-state pouring process. By accurately calibrating the input conditions of wind, wave and current, the hydrodynamic environment characteristics of the construction area are accurately simulated. The dynamic control of the pouring process of the model sand 9 truly reflects the influence of concrete flow on the stress state of the pipe section. The staged test method can systematically evaluate the structural responses under different pouring progress, providing a reliable basis for optimizing the construction technology. The real-time collection and analysis of monitoring data realize the quantitative evaluation of the movement state of the pipe section and the mooring force, significantly improving the prediction accuracy of construction safety.

[0061] This application further proposes that the main body of the immersed tube tunnel model 2 selects an appropriate model scale according to the gravity similarity criterion to fabricate the reinforced concrete immersed tube tunnel model 2 in the non-poured stage. The immersed tube tunnel model 2 and the prototype need to satisfy geometric similarity, static similarity and gravity similarity. The wharf model 3 is fabricated according to the actual wharf structure to simulate the hydrodynamic interference of the wharf on the immersed tube.

[0062] Among them, the gravity similarity criterion means that the mechanical behaviors of the model and the prototype under the action of the gravity field maintain a proportional relationship. Specifically, the model scale can be determined by the principle of equal Froude numbers to ensure that the proportional relationship between the fluid inertial force and the gravity is consistent. The model scale refers to the scaling ratio of the model size to the prototype size. For example, a scale of 1:50 can be used for model scaling, and geometric similarity is achieved by reducing the geometric dimensions in equal proportion. Static similarity means that the equilibrium states of the model and the prototype under the action of hydrostatic pressure maintain a proportional relationship, and the equivalent matching of buoyancy and gravity can be achieved by adjusting the model material density or adding additional counterweights. The reinforced concrete immersed tube tunnel model 2 in the uncast stage refers to the structural state of the tube segment before the second-stage casting. The dynamic change of the structural stiffness during the construction process is reflected by reserving some uncast areas. The wharf model 3 refers to a physical model replicated by scaling the actual wharf structure in equal proportion. Its surface roughness and structural form need to be consistent with the prototype, and it is used to accurately simulate the disturbance effect of the wharf entity on the surrounding flow field.

[0063] Specifically, after determining the model scale based on the Froude similarity criterion, the geometric dimensions of the immersed tube tunnel model 2 are scaled down proportionally, and at the same time, the model material density or additional counterweights are adjusted to meet the static equilibrium conditions. The simulation of the uncast area is achieved by reserving cavities in the model or using low-density filling materials to ensure that the structural stiffness change is consistent with the construction stage. The production of the wharf model 3 needs to restore the underwater pile foundation layout and the shape of the flow baffle of the actual structure to generate a wake flow field similar to the real environment in the test. When wind-wave-current loads are applied in the test pool 1, the hydrodynamic interference between the immersed tube model and the wharf model 3 is achieved through the flow field disturbance of the scale, such as the influence of the eddy current generated behind the wharf pile foundation on the mooring force of the immersed tube.

[0064] Compared with the existing technology, traditional model tests often ignore the influence of the wharf structure on the hydrodynamic characteristics of the immersed tube and only use simplified boundary conditions to simulate the flow field environment. In the existing technology, the model similarity criteria mostly focus on geometric dimension matching and do not systematically consider the comprehensive similarity relationship between gravity and static force, resulting in the test results being unable to reflect the structural response during the actual casting process. This solution realizes the physical simulation of the hydrodynamic coupling effect between the immersed tube and the wharf in the floating casting environment for the first time by establishing a complete multi-dimensional similarity system of gravity-static force-geometry and combining the refined modeling of the wharf structure.

[0065] Through the above technical solutions, this application can accurately reproduce the disturbance effect of the wharf structure on the flow field around the immersed tube in the actual project and effectively solve the problem of the mismatch between the physical characteristics of the test model and the prototype. The dynamic stiffness characteristics of the model in the uncast stage can truly reflect the change of the mechanical behavior of the tube segment structure during the construction process and avoid the interference of the completed casting section on the test data. The test model established based on the multi-dimensional similarity criteria significantly improves the accuracy of the hydrodynamic interaction simulation and provides a reliable physical test basis for evaluating the feasibility of the floating casting process.

[0066] In step S2 of the test method of the present invention, the calibration of the wind-wave-current elements includes the following steps: filling the test pool 1 with water to the set test water level; after the water surface in the test pool 1 is stable, turning on the fan respectively, measuring the wind speed on the windward side of the pipe section through an anemometer, turning on the wave generator, measuring the river wave conditions through a wave height meter, turning on the water pump, and measuring the cross-sectional flow velocity of the river through a moving ship ADCP flow velocity meter; by adjusting the conditions of the fan, wave generator, and water pump respectively, the input conditions required for the test are met.

[0067] Among them, the set test water level refers to the simulated water level corresponding to the prototype water area determined in advance, and specifically, a water level gauge or a liquid level sensor can be used for monitoring, providing the basic water depth condition for subsequent wind-wave-current simulation. Among them, an anemometer refers to an instrument for measuring the gas flow velocity, and specifically, a hot wire type or an ultrasonic type wind speed sensor can be used. By real-time monitoring the wind speed on the windward side of the pipe section, it is ensured that the wind input parameters are consistent with the actual working conditions. Among them, a wave height meter refers to a device for measuring the height of water surface fluctuations, and specifically, a capacitive or resistive sensor can be used. By arranging multiple points, the characteristic parameters of the wave spectrum are obtained to verify whether the wave conditions generated by the wave generator meet the test requirements. Among them, a moving ship ADCP flow velocity meter refers to a device that uses the acoustic Doppler principle to measure the water flow profile, and specifically, a broadband ADCP sensor can be used. By moving along the cross-section to collect the flow velocity distribution data, the three-dimensional reconstruction of the cross-sectional flow velocity field of the river is realized. Among them, adjusting the conditions of the fan, wave generator, and water pump means controlling the output power or operating frequency of the equipment, and specifically, an inverter or a PID controller can be used to adjust the intensity and direction of the wind, waves, and water flow respectively, so that the dynamic combination of multiple environmental elements reaches the test target.

[0068] Specifically, after the test water level is set, the reference environment formed by the stable water surface provides static conditions for the subsequent calibration of elements. After the fan is started, the anemometer collects the wind speed data in real time on the windward side of the pipe section, and through the comparison with the target value, it is fed back to the fan control system to realize the independent calibration of the wind parameters. The waves generated by the wave generator are measured at multiple points through the wave height meter to obtain parameters such as wave height, period, and direction, and the operating parameters of the wave generator are adjusted to make the wave conditions meet the similarity criterion. The water flow driven by the water pump is scanned along the cross-section through the moving ship ADCP to obtain the vertical distribution and transverse gradient of the flow velocity, and the flow rate of the water pump or the angle of the diversion device is adjusted to make the flow velocity field physically similar to the prototype. After the independent calibration of each element is completed, the dynamic balance of the wind-wave-current coupling conditions is realized through linkage control, eliminating the mutual interference between parameters.

[0069] Compared with the prior art, traditional methods usually use fixed parameters to synchronously input wind, wave and current, resulting in difficult precise separation of the coupling between environmental factors. In this solution, through independent calibration of each factor and comprehensive regulation, dedicated measuring equipment is used to calibrate the wind force, wave and current parameters respectively, and then precise simulation of the coupling conditions is achieved through dynamic balance control, solving the problem of test distortion caused by mutual interference of multiple environmental parameters.

[0070] Through the above technical solution, this application realizes independent measurement and precise regulation of the input parameters of wind, wave and current under complex environmental conditions, ensures the physical similarity between the test environment and the actual working conditions, provides reliable environmental input conditions for the model test of the floating state pouring process, and effectively supports the simulation and verification of the subsequent movement response of the pipe section and the pouring process.

[0071] This application further proposes that the cable 4 is composed of a steel cable and a spring, and its force-elongation curve is the same as that of the actual cable 4, and is equipped with a locking buckle mechanism to accurately adjust the length of the cable 4.

[0072] Among them, the steel cable refers to a tensile member formed by stranding multiple metal wires, which can be specifically realized by using stainless steel material, and its cross-sectional diameter is matched according to the scale ratio of the test model to provide the same basic tensile strength as the actual cable 4. Among them, the spring refers to an elastic element with non-linear stiffness characteristics, which can be specifically realized by using a variable pitch helical spring, and its stiffness curve is determined by mechanical parameter calculation to reproduce the non-linear deformation characteristics of the real cable 4 under dynamic loads. Among them, the locking buckle mechanism refers to a mechanical device with length adjustment and fixing functions, which can be specifically realized by using a ratchet locking mechanism, and its tooth pitch accuracy is controlled within the millimeter range to finely adjust the length of the cable 4 in stages during the test and maintain the stability after adjustment.

[0073] Specifically, the steel cable and the spring are connected in series through an end connector to form a composite structure. During the test loading process, the steel cable bears the main tensile load, and the spring absorbs the energy change caused by the dynamic load through its own deformation. The combined characteristics make the force-elongation curve of the model cable 4 completely coincide with the measured data of the prototype cable 4. The locking buckle mechanism is set at the end connection of the cable 4, and the length adjustment is realized by operating the ratchet handle. Each adjustment amount corresponds to the operable adjustment accuracy of the mooring cable 4 in the actual project to ensure the control requirements for the mooring length in different test stages.

[0074] Compared with the prior art, traditional model cables 4 only use a single material to simulate the tensile performance, unable to restore the non-linear elastic characteristics of the real cable 4, and the length adjustment mostly relies on manual knotting or fixture fixing, resulting in problems of low adjustment accuracy and poor operation efficiency. This solution realizes the complete reproduction of mechanical characteristics through the composite structure design, and at the same time uses a mechanical locking mechanism to ensure the quantitative control of length adjustment, significantly improving the simulation accuracy of the mooring system in the model test.

[0075] Through the above technical solutions, the present application realizes the simulation of the true mechanical response of the model cable 4 under dynamic loads, solves the technical bottleneck that the traditional method cannot accurately reproduce the non-linear deformation of the cable 4, and at the same time meets the test requirements of multiple working conditions through a quantifiable length adjustment mechanism, ensuring the reliability of the test data of the dynamic response of the mooring system during the floating casting process of the immersed tube.

[0076] The present application further proposes that the bottom of the crane 5 is equipped with movable wheels to improve the flexibility and coverage of the crane 5, and is equipped with a control system that can move at a specified speed on the wharf to ensure that the pouring funnel 6 it pulls can cover the pouring area.

[0077] Among them, the movable wheels refer to the moving devices installed at the bottom of the crane 5, which can be specifically realized by using universal wheels or track wheels with braking functions, and the crane 5 realizes free displacement in the wharf area through the rolling contact surface, thereby expanding the working range of the crane 5. Among them, the control system refers to the device that controls the moving speed of the crane 5, which can be specifically realized by using a servo motor drive system combined with a preset program, and ensures that the crane 5 maintains a constant speed or variable speed as required during the moving process by setting speed parameters, so as to maintain the stable trajectory of the pouring funnel 6.

[0078] Specifically, the crane 5 realizes translation in the wharf area through the movable wheels installed at the bottom, and the rolling contact surface of the wheels allows the crane 5 to flexibly adjust its position longitudinally or transversely. The control system presets the moving path and speed parameters according to the distribution of the pouring area, drives the crane 5 to move in a specified direction at a constant speed, and pulls the pouring funnel 6 to continuously cover different pouring points. During the moving process, the uniform speed control avoids the fluctuation of the falling speed of the mixed sand caused by the sudden change of acceleration, and the coordinated action of the wheels and the control system enables the pouring area to be completely covered and the mixed sand to be evenly distributed.

[0079] Compared with the prior art, the traditional fixed crane 5 can only perform fixed-point pouring within a limited range, and the lack of speed control of the mobile crane 5 results in uneven distribution of the mixed sand. However, this solution expands the spatial freedom of the crane 5 through movable wheels, combined with a speed-controllable drive system, which not only realizes large-range coverage but also ensures the continuity and uniformity of the pouring process.

[0080] Through the above technical solutions, the present application solves the problems of limited movement of the crane 5 and difficult control of pouring uniformity during the floating casting process, enabling the crane 5 to flexibly adjust its position in a dynamic environment, and at the same time ensuring uniform falling of the mixed sand through speed control, meeting the requirements of floating casting for the movement accuracy and operation continuity of the equipment.

[0081] This application further proposes that the model mixed sand 9 is composed of sands with different densities, and the mixed density is the same as the density of the actual cast concrete; before the experiment, the casting speed of the model mixed sand 9 needs to be calibrated through the valve control system 7, and the falling speed of the mixed sand is the same as the actual casting speed. The valve control system 7 uses an advanced flow control device to adjust the opening size of the valve; the casting formwork 8 is made of a high-strength and low-density material.

[0082] Among them, the model mixed sand 9 being composed of sands with different densities means that the overall density is made the same as the density of the actual concrete by adjusting the proportions of various sands. Specifically, a mixture of quartz sand and barite sand can be used to achieve this, and the density matching is ensured by adjusting the mixing ratio. Among them, the valve control system 7 using an advanced flow control device means that the valve opening is controlled by a mechatronic device. Specifically, a structure in which a stepping motor drives the displacement of the valve plate can be used to achieve this, and the opening size is feedback in real time through a displacement sensor. Among them, the casting formwork 8 being made of a high-strength and low-density material means selecting a material with qualified mechanical properties and a density lower than that of traditional steel. Specifically, a carbon fiber reinforced composite material can be used to achieve this, reducing its own weight while ensuring the stiffness of the formwork.

[0083] Specifically, the precise simulation of the casting process is achieved through the synergistic effect of three technical features: First, the sand mixing ratio is calculated reversely according to the density of the actual concrete, and the model mixed sand 9 with a completely matching density is prepared before the test to eliminate the stress deviation caused by material differences; then, multiple groups of tests are carried out on the falling speed of the mixed sand on a special calibration platform, and the sand falling amount per unit time is made to reach a predetermined value by adjusting the valve opening, forming stable casting speed parameters; finally, a composite material with a high specific strength is used to make the formwork, reducing the influence of the self-weight of the formwork on the floating state of the pipe section to a negligible level while meeting the requirements of casting and forming.

[0084] Compared with the prior art, the traditional test method directly simulates concrete with ordinary sand and gravel, resulting in a material density error exceeding the allowable range; using a manual valve to control the flow rate has defects such as poor adjustment accuracy and large speed fluctuations; using a steel structure formwork causes additional mass to interfere with the test data. This solution realizes the synchronous precise control of the three key parameters of density, flow rate, and structural interference for the first time through triple improvements in material ratio, mechatronic control device, and composite material.

[0085] Through the above technical solutions, this application effectively solves the problems of material density distortion, casting speed deviation, and formwork interference in the model test, enabling key parameters such as the movement response of the pipe section and the force on the cable 4 during the casting process to truly reflect the actual engineering state, providing reliable test data support for the optimization of the floating casting process.

[0086] The present application further proposes a technical solution of setting fiducial points at the central position and corner points of the immersed tube tunnel model 2, and a monitoring instrument is used to monitor the fiducial points to obtain the movement amount of the tube segment and the freeboard value of the corner point.

[0087] Among them, the fiducial point refers to an identifiable mark set at a specific position on the surface of the immersed tube tunnel model 2, which can be specifically realized by using reflective materials, RFID tags or high-contrast coatings. Its function is to provide a spatial positioning reference for the monitoring instrument. The central position fiducial point is used to characterize the overall translational and rotational trends of the tube segment, and the corner point fiducial point is used to capture the change in the freeboard value caused by local deformation. The monitoring instrument refers to a device with the ability to analyze spatial coordinates, which can be specifically realized by using an optical tracking system, a laser scanner or a multi-view vision measurement system. It calculates the six-degree-of-freedom motion parameters of the tube segment and the change in the corner point elevation by collecting the three-dimensional coordinate changes of the fiducial points in real time.

[0088] Specifically, during the floating state casting process, when the immersed tube tunnel model 2 generates complex motions under the action of waves and water currents, the monitoring instrument collects the spatial coordinates of all fiducial points at a fixed frequency. The displacement data of the central position fiducial point is output as the translational parameters of surge, sway, and heave and the rotational parameters of roll, pitch, and yaw of the tube segment after coordinate transformation. The change in the elevation of the corner point fiducial point is compared with the preset reference value to calculate the real-time fluctuation of the freeboard value. By synchronously analyzing the motion correlation between the central position and the corner points, the overall offset and the coupling effect of local deformation of the tube segment under the action of external loads can be identified, providing multi-dimensional motion parameters for evaluating the safety of the casting operation.

[0089] Compared with the prior art, traditional monitoring methods usually only set a single measuring point or rely on inertial measurement units, and cannot simultaneously characterize the dynamic correlation between the overall motion and local deformation of the tube segment. This solution realizes the global analysis of the motion form of the tube segment through the layout of fiducial points distributed in space and the combination of non-contact monitoring instruments. In the prior art, the solutions using water level gauges or single-point displacement sensors are limited by the single measurement dimension and are difficult to reflect the influence of six-degree-of-freedom motion on the casting process. However, this solution can simultaneously obtain comprehensive data of translational, rotational, and freeboard changes through the collaborative work of fiducial points and monitoring instruments.

[0090] Through the above technical solution, the present application can accurately capture the six-degree-of-freedom motion amount and the change in the freeboard value of the corner point of the immersed tube tunnel model 2 under the interference of waves and currents during the floating state casting process, provide data support for optimizing the mooring parameters of the cable 4, effectively avoid the problem of uneven casting caused by motion offset, and improve the accuracy of the construction process simulation. Through the collaborative monitoring of the central and corner point fiducial points, both the overall motion trend of the tube segment can be identified and the influence of local deformation on the construction can be quantified, providing a reliable basis for dynamically adjusting the casting operation parameters.

[0091] The present application further proposes a technical solution of setting fiducial points at the central position and corner points of the immersed tube tunnel model 2, and using monitoring instruments to monitor the fiducial points, so as to monitor the movement amount and the corner freeboard value during the movement of the pipe section.

[0092] Among them, the fiducial point refers to an optical or electromagnetic marker set at a specific position on the surface of the immersed tube tunnel model 2, which can be specifically realized by using a retroreflective prism or a radio frequency identification tag. A spatial positioning reference network is formed by the fiducial points arranged at the center and four corner points of the model. The monitoring instrument refers to a coordinate acquisition system based on the principle of optical tracking or electromagnetic positioning, which can be specifically realized by using an infrared optical tracker or a multi-band electromagnetic locator. By capturing the three-dimensional coordinate changes of the fiducial points in real time, a mathematical model of the movement trajectory of the pipe section is established.

[0093] Specifically, a main fiducial point is set at the geometric center of the top surface of the immersed tube tunnel model 2 to reflect the translational and rotational trends of the overall pipe section; auxiliary fiducial points are set at the edges of the four corners of the model to synchronously capture the displacement changes in the corner area. The monitoring instrument calculates the three linear motion components of surge, sway, and heave, as well as the three angular displacement components of roll, pitch, and yaw by collecting the spatial coordinate data of the fiducial points at high frequency and combining the preset geometric parameters of the pipe section. At the same time, the relative height difference between the corner fiducial point and the water surface of the test pool 1 is calculated in real time to form a dynamic freeboard value monitoring curve, and this value is calibrated by calibrating the water surface reference point.

[0094] In some specific embodiments, the fiducial point is made of a waterproof and highly reflective material to ensure that it can be stably identified by the optical sensor in a wave environment; the monitoring instrument is configured as a multi-camera synchronous acquisition system, and the water surface reflection interference is eliminated by the triangulation algorithm.

[0095] Compared with the prior art, the traditional monitoring method can only obtain some motion parameters through a single inclination sensor, and cannot synchronously obtain the six-degree-of-freedom motion amount and the change of the freeboard value. This solution realizes the comprehensive acquisition of kinematic parameters and hydrostatic parameters by constructing a linkage monitoring mechanism of a spatial positioning network and a water surface reference system, and solves the problem of missing monitoring data caused by the multi-dimensional motion coupling effect in a dynamic wave and current environment.

[0096] Through the above technical solution, the present application can synchronously obtain the six-degree-of-freedom motion trajectory and the dynamic change data of the freeboard height of the immersed tube tunnel model 2 in the floating state pouring test, provide a complete set of kinematic and static datasets for evaluating the stability of the pipe section during the pouring process, and effectively guide the adjustment of the cable 4 system and the optimization of the pouring process.

[0097] The present application further proposes to set fiducial points at the central position and corner points of the immersed tube tunnel model 2, and use monitoring instruments to track the fiducial points to obtain the motion amount and the corner freeboard value during the movement of the pipe section.

[0098] Among them, the central position marking point refers to a positioning mark fixed at the geometric center of the model, which can be specifically implemented using a high-reflectivity material or a radio frequency identification tag, and is used to capture the overall displacement and attitude changes of the pipe section. The corner marking point refers to a monitoring mark set at the top corners of the model structure, which can be specifically implemented using a pressure-sensitive patch or a laser reflection sheet, and is used to detect the local freeboard height fluctuation. The monitoring instrument refers to a tracking system with three-dimensional coordinate measurement capabilities, which can be specifically implemented using an optical motion capture device or a laser scanner. By collecting the spatial coordinate changes of the marking points in real time, the six-degree-of-freedom motion parameters and the corner elevation difference are calculated.

[0099] Specifically, when the model is subjected to external loads, the displacement trajectory of the central marking point is continuously recorded to form a motion trajectory database, which reflects the swaying, surging, and rotational motion states of the pipe section. At the same time, the vertical position changes of the corner marking points are synchronously measured, and the dynamic freeboard value distribution is obtained by calculating the height differences of each corner relative to the still water surface. The monitoring instrument synchronously collects the two types of data at a fixed sampling frequency, and generates a real-time warning signal in combination with the preset freeboard threshold and motion amplitude limit. When it is detected that the corner freeboard value is lower than the safety threshold, the tension adjustment instruction of the cable 4 can be triggered; when it is detected that the roll angle of the pipe section exceeds the design allowable range, a pouring speed adjustment suggestion can be generated.

[0100] Compared with the prior art, traditional monitoring methods mostly use a single-position sensor to measure the overall displacement, unable to distinguish local freeboard changes from the overall motion response, and lacking multi-dimensional data linkage analysis. The buoy-type water level gauge used in the prior art can only measure the average freeboard value and cannot capture the local instability risk caused by corner differences.

[0101] Through the above technical solutions, this application realizes the dual monitoring of the structural motion state and stability during the floating casting process, can accurately identify the center of gravity offset caused by uneven concrete distribution, and timely warns of the risk of corner flooding caused by wave impact, providing a quantitative basis for dynamically adjusting the mooring force distribution of the cable 4 and the pouring operation sequence, and effectively avoiding the overturning of the pipe section or structural damage during the pouring process.

[0102] The reinforced concrete immersed tube tunnel floating state pouring test device and method provided by the embodiments of the present invention have remarkable beneficial effects: By equipping the crane 5 control system and high-precision funnel valves, and using equal-density mixed sand instead of floating state pouring concrete, it can accurately simulate the floating state pouring process of the immersed tube tunnel, including the movement displacement, attitude, acceleration and force change laws of the pipe section at different pouring stages, as well as the force change law of the cable 4, so as to provide reliable data support for the rationality of the pipe section floating state pouring scheme. At the same time, the simulation input conditions of the harbor pool wind-wave-current system, combined with the proportionally made wharf model 3, immersed tube tunnel model 2 and cable 4, can provide a background similar to the actual engineering environment for the test, ensure that the interaction and mechanical relationship between various components during the test are consistent with the actual situation, and ensure the accuracy and reliability of the test. In addition, the present invention can not only accurately simulate the floating state pouring process of the immersed tube tunnel, but also be applicable to the simulation of the floating state pouring process of other types of floating bodies on the water, with wider applicability and representativeness, and can more reasonably reflect the movement response of the immersed tube and the mooring force, providing more valuable reference for related projects. Through accurate simulation and test accuracy guarantee, the present invention can provide detailed and accurate data for the rationality of the pipe section floating state pouring scheme, help engineering and technical personnel better optimize the construction scheme, predict possible problems in advance and take corresponding measures, reduce construction risks, improve construction quality and efficiency, at the same time enhance the safety of the project, reduce potential safety hazards caused by uncertainties and risk factors during the construction process, extend the service life of the project, and provide more reliable infrastructure guarantee for the development of society and economy.

[0103] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention.

[0104] The above embodiments are only described for the preferred mode of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solution of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A floating casting test device for a reinforced concrete immersed tube tunnel, characterized in that Comprising: A test pool (1) for simulating the actual water environment; A pipe joint mooring model, including a submerged tube tunnel model (2), a wharf model (3) and a cable (4). The submerged tube tunnel model (2) and the wharf model (3) are respectively placed in the test pool (1), and the bottom of the submerged tube tunnel model (2) is connected to the cable (4) to simulate the stiffness characteristics and dynamic response of the actual mooring system; A floating state casting model, including a crane (5), a casting funnel (6) and a casting formwork (8). The casting funnel (6) is filled with model sand (9) inside, and the bottom is open and connected to a valve control system (7) to adjust the falling speed of the model sand (9); Monitoring instruments, including a cable force meter and a six-degree-of-freedom monitor, are installed on the pipe joint and the cable (4) for obtaining the mooring force and the pipe joint motion parameters in real time.

2. The reinforced concrete immersed tube tunnel floating state casting test device according to claim 1, characterized in that, A flow generating and wave generating device, including a fan, a wave generator and a water pump, is arranged in the test pool (1) for generating set environmental conditions.

3. The reinforced concrete immersed tube tunnel floating state casting test device according to claim 1, characterized in that, The model sand (9) is composed of sand grains with different particle sizes and densities mixed in proportion to make its unit weight consistent with that of the prototype concrete.

4. The reinforced concrete immersed tube tunnel floating state casting test device according to claim 3, characterized in that, The model sand mixing (9) is obtained by mixing iron sand and quartz sand, and its density is 2.4 g / cm 3 .

5. The test device for floating state casting of reinforced concrete immersed tunnel according to claim 1, characterized in that, Marking points are arranged at the center and corner positions of the submerged tube tunnel model (2) to assist the monitoring instruments in obtaining the pipe joint motion amount and the corner freeboard value.

6. The test device for floating casting of reinforced concrete immersed tunnel according to claim 1, wherein The six-degree-of-freedom monitor adopts a real-time high-speed six-dimensional dynamic tracking system and is equipped with a 2000Hz high-speed infrared array camera.

7. The test device for floating-state casting of a reinforced concrete immersed tunnel according to claim 1, wherein, The floating state casting model further includes a casting formwork (8) for installing into the submerged tube tunnel model (2).

8. A floating state casting test method for a reinforced concrete immersed tube tunnel, which uses the floating state casting test device for a reinforced concrete immersed tube tunnel described in any one of claims 1 to 7, and is characterized in that, Including the following steps: Step S1, fabricating the submerged tube tunnel model (2), the wharf model (3) and the cable (4) according to the parameters design; Step S2, calibrating the input conditions of wind, wave and current; Step S3, installing the casting formwork (8) into the submerged tube tunnel model (2); Step S4, turning on the cable force meter and the six-degree-of-freedom monitor, turning on the input conditions of wind, wave and current, and waiting for the input conditions to be stable; Step S5, opening the bottom valve of the casting funnel (6) to make the model sand (9) uniformly fall into the casting formwork (8); Step S6, closing the input conditions of wind, wave and current, closing the monitoring instruments, adjusting the length of the cable (4), and conducting the next-stage casting test.

9. The method for the floating state casting test of a reinforced concrete immersed tube tunnel according to claim 8, wherein, In the step S2, the calibration of the input conditions of wind, wave and current includes the following steps: Adding water to the test pool (1) to the set test water level; After the water surface in the test pool (1) is stable, turning on the fan, measuring the wind speed on the windward side of the pipe joint through an anemometer, turning on the wave generator, measuring the river wave conditions through a wave height meter, and turning on the water pump, measuring the river cross-section flow velocity through a flow meter.

10. The method for the floating state casting test of a reinforced concrete immersed tube tunnel according to claim 8, characterized in that, During the casting process, the motion amount and the corner freeboard value of the submerged tube tunnel model (2) are monitored in real time, and the length of the cable (4) and the casting speed are adjusted according to the monitoring data to ensure the stability of the pipe joint.

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