Trenchless Repair System for Drainage Pipelines in Cold Regions – Integrated Freeze-Thaw and Vibration Testing Device

Abstract

This application provides an integrated freeze-thaw and vibration testing device for trenchless repair systems of drainage pipelines in cold regions, comprising: an insulated shell, a six-degree-of-freedom vibration platform, a low-temperature environment control unit, a multi-field loading unit, a quick-change specimen slot, a distributed monitoring system, an integrated control and acquisition center, and a sealed interface module. The insulated shell forms a sealed insulated cavity, and the low-temperature environment control unit and the six-degree-of-freedom vibration platform are housed within this cavity. Both the low-temperature control unit and the six-degree-of-freedom vibration platform are connected to the integrated control and acquisition center. This device can efficiently, reliably, and with low energy consumption acquire multi-field response data of trenchless repair systems for drainage pipelines in cold regions under freeze-thaw and seismic coupling, providing scientific and precise experimental support for repair material design, interface durability assessment, and seismic performance improvement. It has significant engineering application value and economic benefits.

Description

Technical Field

[0001] This application relates to the field of drainage pipeline repair technology, and more specifically, to a comprehensive freeze-thaw and vibration testing device for trenchless repair of drainage pipelines in cold regions – soil integration. Background Technology

[0002] Due to the coupled effects of natural freeze-thaw cycles and seismic activity, municipal drainage pipelines in cold regions often suffer from defects such as joint cracking, structural instability, leakage, and lining delamination. Trenchless repair techniques for aging pipelines (such as CIPP, inverted lining, and spiral winding) have been widely used in engineering projects both domestically and internationally. However, systematic research is still lacking on the adhesion degradation between the repair layer and the original pipeline in frigid environments, freeze-thaw fatigue resistance, and ground vibration response.

[0003] Current experimental studies mostly employ a "two-step method" or a "split device"—first completing freeze-thaw cycles in a low-temperature chamber, then transferring the specimen to a vibration table for dynamic loading. This approach has the following significant drawbacks:

[0004] 1. Poor operating condition coupling The temperature gradient and micro-cracks formed during freeze-thaw cycles are easily disturbed during handling and reinstallation, making it difficult to accurately maintain the post-freeze-thaw interface damage state. Furthermore, the inability to apply ground vibration synchronously causes the "freeze-thaw-vibration" coupling mechanism to deviate from reality.

[0005] 2. Simplified loading boundary conditions Most shaking table tests only consider the pipe body itself, while ignoring the confining pressure of the undisturbed soil and the groundwater pressure, which results in the failure to reflect the structure-soil interaction effect.

[0006] Internal water pressure, earth pressure and longitudinal constraints are often simulated as constant static loads, lacking linkage control that changes in real time with temperature and vibration.

[0007] 3. Low specimen replacement efficiency Traditional freezing chambers or vibration table fixtures are poorly adaptable to specimens of different diameters and repair methods, and are time-consuming to disassemble and assemble, affecting test turnover and parameter comparison.

[0008] 4. Limitations in monitoring methods The lack of a high-precision, distributed multi-field (temperature, strain, displacement, interfacial bond stress) synchronous acquisition system makes it impossible to capture the entire process of interface debonding under freeze-thaw crack propagation and ground vibration.

[0009] The results rely heavily on a small amount of data from strain gauges or displacement gauges, resulting in insufficient spatial resolution and making it difficult to reveal the mechanisms of local failure.

[0010] 5. Insufficient integration of low-temperature vibration devices Existing low-temperature vibration equipment typically only covers single-degree-of-freedom or small-amplitude loading, making it impossible to simulate the three-dimensional dynamic characteristics of drainage pipes under seismic loading. Furthermore, the temperature control system and vibration control system operate independently, and mutual interference from temperature fluctuations and vibration noise is difficult to eliminate, affecting data accuracy.

[0011] 6. Insufficient degrees of freedom Most vibration tables used are unidirectional or simple six-degree-of-freedom vibration tables, which are difficult to simulate actual three-dimensional ground vibration and difficult to capture interfacial adhesion. Failure process - high rate of missed detection due to localized damage 7. Insufficient monitoring dimensions and accuracy: relying solely on point strain gauges and accelerometers. Difficulty in capturing the entire process of interfacial bonding failure - high rate of missed detection due to localized damage 8. Low system integration, large footprint, and high energy consumption: The temperature control system and vibration system operate separately, causing mutual interference. The temperature control accuracy is ±3℃ or higher, and the equipment operates with high noise amplitude and high data noise. 9. High safety and maintenance risks: Frequent hoisting, easy damage to connecting wires, risk of specimen falling during hoisting, and personnel injury - High failure rate due to repeated plugging and unplugging of sensor circuits. Therefore, there is an urgent need for a comprehensive testing device that can simultaneously load low-temperature freeze-thaw cycles and multi-degree-of-freedom seismic vibrations under laboratory conditions, while also considering actual working conditions such as soil confining pressure and internal water pressure, in order to accurately evaluate the seismic performance and interfacial bonding durability of trenchless repair systems for drainage pipelines in cold regions, and provide reliable experimental support for repair scheme design and life prediction. Summary of the Invention

[0012] In view of this, this application provides a comprehensive freeze-thaw and vibration testing device for trenchless repair of drainage pipelines in cold regions, in order to overcome the above-mentioned defects in the prior art.

[0013] To achieve the above objectives, the technical solution adopted in this application is as follows: A comprehensive freeze-thaw and vibration testing device for trenchless repair of drainage pipelines in cold regions, comprising: an insulated shell, a six-degree-of-freedom vibration platform, a low-temperature environment control unit, a multi-field loading unit, a quick-change specimen slot, a distributed monitoring system, a comprehensive control and acquisition center, and a sealed interface module; the insulated shell forms a sealed insulated cavity, and the low-temperature environment control unit and the six-degree-of-freedom vibration platform are housed within the sealed insulated cavity; both the low-temperature control unit and the six-degree-of-freedom vibration platform are connected to the comprehensive control and acquisition center; the distributed monitoring system is integrated into the PXI-e chassis of the comprehensive control and acquisition center via the sealed interface module; the insulated shell adopts a double-layer Q235 steel plate and vacuum insulation layer structure, and the inner surface is sprayed with an epoxy moisture-proof coating; the six-degree-of-freedom vibration platform adopts an electro-hydraulic servo parallel mechanism and is fixed to the bottom plate of the insulated shell through a heat insulation and vibration damping layer.

[0014] Furthermore, the low-temperature environment control unit includes a liquid nitrogen spray assembly, a temperature-controlled zoned heating film, and a forced convection fan. The atomizing nozzles of the liquid nitrogen spray assembly are arranged in an array on the top and sides of the insulation shell. The temperature-controlled zoned heating film is attached to the inner wall of the insulation shell to achieve programmed temperature control from -40 ℃ to +20 ℃. The forced convection fan is used to ensure temperature uniformity.

[0015] Furthermore, the multi-field loading unit includes an earth pressure loading module, an internal water pressure loading module, and an axial loading module. The earth pressure loading module consists of 12 servo-driven push actuators evenly distributed circumferentially, with a self-aligning cryogenic sealing sleeve installed at the piston rod penetration point of each servo-driven push actuator. The internal water pressure loading module consists of a flexible water bladder and a CNC constant pressure pump, enabling continuously adjustable internal water pressure loading from 0 to 200 kPa. The axial loading module is a top-mounted bidirectional cylinder capable of applying an axial load of ±100 kN, with a self-aligning cryogenic sealing sleeve also installed at the piston rod penetration point of the top-mounted bidirectional cylinder.

[0016] Furthermore, the quick-change specimen slot is composed of two semi-annular high-strength aluminum alloy frames and radial wedge locking components; The slot bottom plate is equipped with a positioning tenon, which cooperates with the T-slot of the vibration table to ensure repeatability positioning accuracy ≤0.3 mm.

[0017] Furthermore, the distributed monitoring system includes a fiber Bragg grating network, a MEMS accelerometer array, a displacement sensing chain, and a temperature-humidity probe. The fiber Bragg grating network is spirally arranged along the interface between the repair layer and the original tube. The MEMS accelerometer array has a range of ±5 g and a sampling rate of 1 kHz. The displacement sensing chain is composed of several circumferentially arranged fiber optic displacement gauges with a range of 25 mm. The temperature-humidity probe includes multiple synchronously collected data points.

[0018] Furthermore, the integrated control and acquisition center includes a PXI-e host and an FPGA; the sealed interface module adopts a quick-connect cryogenic sealing connector, which integrates four channels: electro-optical-hydraulic-gas. Furthermore, the integrated testing device also includes a heat insulation and vibration damping layer, which is composed of a composite silicone aerogel board and cavity vibration isolation rubber, so that vibration energy is not transmitted to the heat insulation shell and thermal bridging is avoided.

[0019] Furthermore, the servo actuator through-wall seal uses a four-lip PTFE-FKM combination ring, the bottom of the insulation shell is equipped with a dual-way overpressure valve and a liquid nitrogen leak detector, and the top cover has mechanical-electrical double interlocking and a pneumatic lifting mechanism.

[0020] Compared with the prior art, the beneficial effects of this application are: 1. Freeze-thaw and seismic synchronous coupling to realistically reproduce service conditions. The low-temperature environment control unit and the six-degree-of-freedom vibration platform are placed in a sealed, insulated cavity. The temperature-vibration triggering error is ≤ 10 ms, and the temperature rise of the specimen during the entire loading process is < 1 ℃.

[0021] The test results show that the attenuation law of interfacial bonding strength and the error of on-site monitoring have converged from ±15% of the traditional device to ±5%, which significantly improves the reliability of the parameters.

[0022] 2. Real-time closed-loop loading at multiple boundary levels improves the accuracy of seismic performance evaluation. Earth pressure, internal water pressure, and axial load can all be linked in real time according to the seismic spectrum, and the loading error is controlled within ±2 kPa / ±1 kN.

[0023] Compared with the fixed boundary test, the captured peak circumferential strain of the pipeline increased by 30% to 40%, fully revealing the soil-pipe-water coupling effect.

[0024] 3. A six-degree-of-freedom vibration platform that fully reproduces three-dimensional seismic motion. Peak accelerations in the X, Y, and Z directions can be superimposed simultaneously, with a programmable frequency of 0.5–50 Hz. Compared to uniaxial vibration, the maximum shear strain amplification factor of the specimen is increased by 1.6 times, avoiding underestimation of the safety margin.

[0025] 4. Quick-change specimen slots significantly improve testing efficiency. The disassembly and assembly time has been reduced from the traditional 1.5 hours to 5 minutes; ≥10 sets of parameter comparison tests can be completed per day, and the turnover efficiency has been improved by more than 15 times, significantly saving manpower and liquid nitrogen consumption.

[0026] 5. Distributed multi-field monitoring, capturing the entire process of destruction with high spatial-temporal resolution. Fiber Bragg grating + MEMS array with 1 kHz synchronous sampling and spatial resolution <10 mm enables real-time imaging of freeze-thaw crack propagation and bonding failure.

[0027] Compared to point strain gauges, the error in determining the initiation of interface debonding is reduced from 0.8 s to 0.1 s, providing high-precision data for mechanism analysis and numerical model verification.

[0028] 6. Integrated temperature and vibration control with thermal insulation and vibration reduction design reduces energy consumption and noise. Vacuum insulation layer and composite vibration isolation rubber block cold bridges, reduce liquid nitrogen usage by 35%, and reduce noise by 8 dB; temperature uniformity is improved from ±3 ℃ to ±0.5 ℃.

[0029] 7. No hoisting required and modular interface significantly improves test safety and reliability. Eliminating the need for handling entire containers and frequent plugging and unplugging avoids the risk of falling from heights; sensor failure rate decreases by 60%, significantly reducing maintenance costs. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the overall structure of the integrated freeze-thaw and vibration test device for trenchless repair of drainage pipelines in cold regions, as described in this application.

[0032] Figure 2 This is a longitudinal cross-sectional schematic diagram of the integrated freeze-thaw and vibration test device for trenchless repair of drainage pipelines in cold regions, as described in this application.

[0033] Figure 3 This is a block diagram illustrating the temperature control and vibration coordinated control principle of the integrated freeze-thaw and vibration testing device for trenchless repair of drainage pipelines in cold regions, as described in this application.

[0034] Figure 4 This is a flowchart of the multi-field loading process for the integrated freeze-thaw and vibration testing device for trenchless repair of drainage pipelines in cold regions, as described in this application.

[0035] Figure 5 This is a timing diagram of the sensing and data acquisition of the integrated freeze-thaw and vibration test device for trenchless repair of drainage pipelines in cold regions, as described in this application.

[0036] Figure 6 is a partially enlarged structural diagram of the quick-change specimen slot of the integrated freeze-thaw-vibration test device for trenchless repair of drainage pipelines in cold regions in this application.

[0037] Figure 7 is a partial cross-sectional view (left) and top view (right) of the positioning tenon and the T-slot of the vibration table of the integrated freeze-thaw-vibration test device for trenchless repair of drainage pipelines in cold regions in this application.

[0038] The attached diagram includes: thermal insulation shell-1, top cover-10, six-degree-of-freedom vibration platform-2, low-temperature environment control unit-3, multi-field loading unit-4, quick-change specimen slot-5, distributed monitoring system-6, integrated control and acquisition center-7; sealing interface module-8, thermal insulation and shock absorption layer-9, positioning tenon-10, vibration table T-slot-11, nitrogen spray assembly-31, temperature-controlled zoned electric heating film-32, forced convection air-33, earth pressure loading module-41, internal water pressure loading module-42 and axial loading module-43, two-half-ring high-strength aluminum alloy frame-51, radial wedge locking component-52, fiber optic grating network-61, MEMS accelerometer array-62, displacement sensing chain-63, temperature-humidity probe-64, PXI-e host-71 and FPGA-72. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0040] like Figure 1 and Figure 2 As shown, the integrated freeze-thaw and vibration testing device for trenchless repair of drainage pipelines in cold regions includes: an insulated shell 1, a six-degree-of-freedom vibration platform 2, a low-temperature environment control unit 3, a multi-field loading unit 4, a quick-change specimen slot 5, a distributed monitoring system 6, an integrated control and acquisition center 7, and a sealed interface module 8. The insulated shell forms a sealed insulated cavity, and the low-temperature environment control unit and the six-degree-of-freedom vibration platform are housed within this cavity. Both the low-temperature control unit 3 and the six-degree-of-freedom vibration platform 2 are connected to the integrated control and acquisition center 7. The distributed monitoring system 6 is integrated into the PXI-e chassis of the integrated control and acquisition center 7 via the sealed interface module 8. The insulated shell 1 uses a double-layer Q235 steel plate and vacuum insulation layer structure, with an epoxy moisture-proof coating sprayed on the inner surface. The six-degree-of-freedom vibration platform 2 uses an electro-hydraulic servo parallel mechanism and is fixed to the base plate of the insulated shell 1 through a heat-insulating and vibration-damping layer.

[0041] Specifically, the external dimensions of the heat-insulating shell 1 can be 2.6 m × 2.0 m × 2.2 m; the top cover 10 is equipped with a pneumatic lifting mechanism, which can complete the opening / closing within 60 seconds.

[0042] By adopting an integrated insulated shell and a shared closed-loop control system, the temperature control accuracy is improved to ±0.5 ℃, while reducing system energy consumption and vibration-temperature cross-noise. This solves the technical problems of dispersed temperature control and vibration systems, high energy consumption, and mutual interference in existing technologies.

[0043] The six-degree-of-freedom vibration platform 2 has a platform size of 1.2 m × 1.2 m and a load capacity of 10 kN. It adopts an electro-hydraulic servo parallel mechanism, with a maximum displacement of ±50 mm in the X / Y / Z directions, a rotation angle of ±6°, a frequency of 0.5-50 Hz, and can superimpose three-dimensional time history waves. It is fixed to the bottom plate of the thermal insulation shell 1 through a heat insulation and vibration damping layer 9 to avoid cold bridging.

[0044] See Figure 3 Temperature control-vibration coordination: Both the low-temperature control unit 3 and the vibration platform 2 are scheduled by the integrated control and acquisition center 7; when the temperature reaches the set value, the system automatically triggers the vibration waveform loading, and the timing error between the two is ≤10 ms.

[0045] This application integrates a six-degree-of-freedom micro-vibration platform, supporting 0–50 Hz frequency sweep and superimposed triaxial acceleration, meeting the amplitude-frequency compatibility and programmable control requirements for three-dimensional excitation of seismic motion in cold regions. It solves the technical problems of insufficient degrees of freedom and simulation accuracy in existing vibration tables.

[0046] Furthermore, the low-temperature environment control unit 3 includes a liquid nitrogen spray assembly 31, a temperature-controlled zoned electric heating film 32, and a forced convection fan 33. The atomizing nozzles of the liquid nitrogen spray assembly 31 are arranged in an array on the top and sides of the insulation shell 1. The temperature-controlled zoned electric heating film 32 is attached to the inner wall of the insulation shell 1 to achieve programmed temperature rise and fall from -40 ℃ to +20 ℃. The forced convection fan 33 is used to ensure temperature uniformity.

[0047] Furthermore, the multi-field loading unit includes an earth pressure loading module, an internal water pressure loading module, and an axial loading module. The earth pressure loading module consists of 12 servo-driven push actuators evenly distributed circumferentially, with a self-aligning cryogenic sealing sleeve installed at the piston rod penetration point of each servo-driven push actuator. The internal water pressure loading module consists of a flexible water bladder and a CNC constant pressure pump, enabling continuously adjustable internal water pressure loading from 0 to 200 kPa. The axial loading module is a top-mounted bidirectional cylinder capable of applying an axial load of ±100 kN, with a self-aligning cryogenic sealing sleeve also installed at the piston rod penetration point of the top-mounted bidirectional cylinder.

[0048] The term "self-aligning" is a functional term in mechanical structures, referring to the fact that the "low-temperature sealing sleeve" has a certain self-aligning capability at the piston rod through-wall. When the piston rod and the axis of the through-wall hole are slightly misaligned or tilted due to vibration, assembly errors, or low-temperature shrinkage, the structure's floating / spherical fit can automatically compensate for the misalignment, thereby allowing the sealing lip to maintain a more uniform contact pressure on the piston rod and reducing the risk of uneven wear and leakage.

[0049] See Figure 3 Multi-field loading closed loop: Earth pressure, internal water pressure and axial load are fed back in real time by pressure sensors and displacement encoders. The control center synchronously adjusts the opening of the servo valve according to the preset working condition curve to achieve multi-field coupling.

[0050] The maximum static pressure of the earth pressure loading module 41 is 300 kPa.

[0051] This application provides a solution that integrates a low-temperature environment control unit and a multi-degree-of-freedom vibration loading unit into the same sealed test chamber, so that the specimen can be directly subjected to vibration loading under controlled temperature conditions throughout the process, avoiding temperature rise and microcrack disturbance, and truly reproducing the freeze-thaw-earthquake coupling effect.

[0052] Meanwhile, by designing a multi-channel servo loading module, confining pressure, internal pressure, and longitudinal loads can be applied accurately and dynamically in low-temperature environments, enabling the reproduction of multi-field coupled boundary conditions between the pipeline, soil, and water pressure. This solves the technical problem of the lack of real-time controllable earth pressure, internal water pressure, and axial constraint loading boundary conditions in existing technologies.

[0053] Furthermore, this application completely eliminates the specimen hoisting process through a fixed test chamber and modular sensing interfaces, reducing personnel risks and improving the reliability and lifespan of sensors and circuitry. It also addresses the safety and maintenance risks associated with frequent hoisting and repeated plugging and unplugging of circuitry.

[0054] Further, see Figure 6 and Figure 7 The quick-change specimen slot 5 is composed of two half-ring high-strength aluminum alloy frames 51 and radial wedge locking parts 52; the bottom plate of the slot 5 is equipped with a positioning tenon 10, which cooperates with the T-slot 11 of the vibration table to ensure repeatability positioning accuracy ≤0.3 mm.

[0055] The quick-change specimen slot 5 is compatible with Φ300-Φ800 mm repair-original pipe-soil combination specimens, and can be loaded and unloaded within 5 minutes.

[0056] This application employs a universal combination slot that allows for quick locking and releasing, enabling the replacement of specimens of different diameters and repair methods within 5 minutes, ensuring boundary consistency and significantly improving test turnaround time. It solves the technical problems of slow specimen assembly and disassembly and low parameter comparison efficiency in existing technologies.

[0057] Furthermore, the distributed monitoring system 6 includes a fiber optic grating network 61, a MEMS accelerometer array 62, a displacement sensing chain 63, and a temperature-humidity probe 64. The fiber optic grating network 61 is spirally arranged along the interface between the repair layer and the original tube. The MEMS accelerometer array 62 has a range of ±5 g and a sampling rate of 1 kHz. The displacement sensing chain 63 is composed of several circumferentially arranged fiber optic displacement gauges with a range of 25 mm. The temperature-humidity probe 64 includes multiple synchronously collected data points.

[0058] Specifically, the fiber optic grating network 61 has a resolution of 1 με; the displacement sensing chain 63 is composed of 8 circumferentially arranged fiber optic displacement gauges with a range of 25 mm; and the temperature-humidity probe 64 includes 20 synchronously collected data points.

[0059] See Figure 3 Data acquisition: The optical / electrical signals of the distributed monitoring system 6 are fed into the PXI-e chassis via the sealed interface module 8. The FPGA is responsible for high-speed caching and preliminary filtering, and the CPU performs real-time visualization.

[0060] This application introduces a distributed fiber strain, MEMS acceleration and interface displacement collaborative measurement system to achieve high spatial resolution synchronous acquisition and online analysis of temperature-strain-potential multi-field information, solving the technical problems of limited measurement dimensions and difficulty in capturing the entire process of interface adhesion degradation in the prior art.

[0061] Furthermore, the integrated control and acquisition center 7 includes a PXI-e host 71 and an FPGA 72; the sealed interface module adopts a quick-connect cryogenic sealed connector, which integrates four channels: electrical, optical, liquid, and gas.

[0062] The integrated control and acquisition center 7 adopts a PXI-e host + FPGA coprocessor to realize closed-loop control of temperature, vibration, and each loading channel; and the update frequency can be set to 1 kHz, the data bus rate is 10 Gbps; it supports online FFT and real-time imaging of crack evolution maps.

[0063] Furthermore, the integrated testing device also includes a heat insulation and vibration damping layer, which is composed of a composite silicone aerogel board and cavity vibration isolation rubber, so that vibration energy is not transmitted to the heat insulation shell and thermal bridging is avoided.

[0064] Furthermore, the servo actuator's through-wall seal uses a four-lip PTFE-FKM combination ring, which can withstand -50 ℃ and 20MPa pressure; the bottom of the insulation shell is equipped with a dual-way overpressure valve and a liquid nitrogen leak detector, and the top cover has mechanical-electrical double interlocking and a pneumatic lifting mechanism.

[0065] Workflow (see Figures 4 and 5) 1. Specimen Installation Open the top cover → Place the slot on the table → Insert the assembled specimen → Lock the wedge → Connect the sensing optical cable.

[0066] 2. Precooling and freeze-thaw cycles The system cools down to the target low temperature T1T_1T1 → holds at t1t_1t1 → heats up to T2T_2T2 → holds at t2t_2t2; the number of cycles is automatically recorded.

[0067] 3. Coupled vibration - multi-field loading The vibration platform is triggered according to the preset earthquake waveform, and the servo loading module applies synchronous confining pressure / internal pressure / axial force at the same time.

[0068] 4. Data Synchronous Acquisition The timing sequence shown in Figure 5 is as follows: five signals—temperature, pressure, strain, acceleration, and displacement—are synchronously sampled at 1 kHz, and corresponding loading commands are written into the metadata of the same frame to achieve multi-field coupling recording of the entire process.

[0069] 5. Specimen replacement Remove the wedge block → disassemble the slot → insert the next set of specimens → repeat steps 2-4.

[0070] It should be noted that the soil filling for the test specimens in this application uses controllable frozen soil with particle size distribution and a compaction degree of 95%; after filling, it is degassed under vacuum to prevent freezing. The control software is based on LabVIEW and has built-in vibration-temperature control interlock logic and abnormal over-limit emergency stop protection. The bottom of the insulation shell 1 is equipped with a dual-way overpressure valve and a liquid nitrogen leak detector, and the top cover has mechanical and electrical double interlocks to ensure safety.

[0071] This application enables high-precision and rapid testing of trenchless repair systems for drainage pipelines in cold regions under low-temperature, freeze-thaw, vibration, and multi-field boundary coupling conditions. It can also efficiently, reliably, and with low energy consumption acquire full-process data of the multi-field response of trenchless repair systems for drainage pipelines in cold regions under freeze-thaw and seismic coupling. This provides scientific and precise experimental support for repair material design, interface durability assessment, and seismic performance improvement, and has significant engineering promotion value and economic benefits.

[0072] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A comprehensive freeze-thaw and vibration testing device for trenchless repair of drainage pipelines in cold regions, characterized in that... include: The system comprises an insulated shell, a six-degree-of-freedom vibration platform, a low-temperature environment control unit, a multi-field loading unit, a quick-change specimen slot, a distributed monitoring system, an integrated control and acquisition center, and a sealed interface module. The insulated shell forms a sealed insulated cavity, within which the low-temperature environment control unit and the six-degree-of-freedom vibration platform are housed. Both the low-temperature control unit and the six-degree-of-freedom vibration platform are connected to the integrated control and acquisition center. The distributed monitoring system is integrated into the PXI-e chassis of the integrated control and acquisition center via the sealed interface module. The insulated shell uses a double-layer Q235 steel plate and a vacuum insulation layer structure, with an epoxy moisture-proof coating sprayed on the inner surface. The six-degree-of-freedom vibration platform employs an electro-hydraulic servo parallel mechanism and is fixed to the base plate of the insulated shell via a heat-insulating and vibration-damping layer.

2. The integrated freeze-thaw and vibration testing device for trenchless repair of drainage pipelines in cold regions as described in claim 1, characterized in that, The low-temperature environment control unit includes a liquid nitrogen spray assembly, a temperature-controlled zoned electric heating film, and a forced convection fan. The atomizing nozzles of the liquid nitrogen spray assembly are arranged in an array on the top and sides of the insulation shell. The temperature-controlled zoned electric heating film is attached to the inner wall of the insulation shell to achieve programmed temperature rise and fall from -40 ℃ to +20 ℃. The forced convection fan is used to ensure temperature uniformity.

3. The integrated freeze-thaw and vibration testing device for trenchless repair of drainage pipelines in cold regions as described in claim 1 or 2, characterized in that... The multi-field loading unit includes an earth pressure loading module, an internal water pressure loading module, and an axial loading module. The earth pressure loading module consists of 12 servo-driven push actuators evenly distributed circumferentially, with a self-aligning cryogenic sealing sleeve installed at the piston rod penetration point of each servo-driven push actuator. The internal water pressure loading module consists of a flexible water bladder and a CNC constant pressure pump, enabling continuously adjustable internal water pressure loading from 0 to 200 kPa. The axial loading module is a top-mounted bidirectional cylinder capable of applying an axial load of ±100 kN, and the piston rod penetration point of the top-mounted bidirectional cylinder is also equipped with a self-aligning cryogenic sealing sleeve.

4. The integrated freeze-thaw and vibration testing device for trenchless repair of drainage pipelines in cold regions as described in claim 3, characterized in that, The quick-change specimen slot is composed of two semi-annular high-strength aluminum alloy frames and radial wedge locking components. The card slot base plate is equipped with a positioning tenon, which cooperates with the T-slot of the vibration table to ensure repeatability positioning accuracy ≤0.3mm.

5. The integrated freeze-thaw and vibration testing device for trenchless repair of drainage pipelines in cold regions as described in claim 1, characterized in that... The distributed monitoring system includes a fiber Bragg grating network, a MEMS accelerometer array, a displacement sensing chain, and a temperature-humidity probe. The fiber Bragg grating network is spirally arranged along the interface between the repair layer and the original tube. The MEMS accelerometer array has a range of ±5 g and a sampling rate of 1 kHz. The displacement sensing chain is composed of several circumferentially arranged fiber optic displacement gauges with a range of 25 mm. The temperature-humidity probe includes multiple synchronously collected data points.

6. The integrated freeze-thaw and vibration testing device for trenchless repair of drainage pipelines in cold regions as described in claim 1, characterized in that, The integrated control and acquisition center includes a PXI-e host and an FPGA; the sealed interface module adopts a quick-connect cryogenic sealed connector, which integrates four channels: electrical, optical, liquid, and gas.

7. The integrated freeze-thaw and vibration testing device for trenchless repair of drainage pipelines in cold regions as described in claim 1, characterized in that, The comprehensive testing device also includes a heat insulation and vibration damping layer, which is composed of a composite silicone aerogel board and cavity vibration isolation rubber, so that vibration energy is not transmitted to the heat insulation shell and thermal bridging is avoided.

8. The integrated freeze-thaw and vibration testing device for trenchless repair of drainage pipelines in cold regions as described in claim 1, characterized in that, The servo actuator through-wall seal uses a four-lip PTFE-FKM combination ring. The bottom of the insulation shell is equipped with a dual-way overpressure valve and a liquid nitrogen leak detector. The top cover has mechanical-electrical double interlocking and a pneumatic lifting mechanism.

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