Co-construction method for multi-layer urban underground complex and urban bridge

Abstract

The invention relates to the technical field of underground structure construction, and particularly discloses a multi-layer urban underground complex and urban bridge co-construction method which comprises the steps of S1, foundation pit support and foundation replacement, S2, integrated pier stud-floor prefabrication, S3, microclimate regulation and burying, S4, bridge floor beam and slab synchronous hoisting and S5, dynamic monitoring and feedback regulation and control. According to the construction method, the overground bridge component and the underground complex structure are constructed synchronously, staged waiting and secondary construction are not needed, working procedure switching and time waste between construction nodes are effectively eliminated, and the project propulsion efficiency is remarkably improved. Pier column-floor slab integrated pouring is connected with an annular bearing platform beam, a unified bearing framework is formed, cooperative sharing of vertical and transverse loads is achieved, the risk of local stress concentration is reduced, the overall anti-seismic and anti-floating capacity is enhanced, a heat exchange and phase change energy storage device is arranged in an underground space, and a self-stabilizing temperature and humidity balance environment is created. Mechanical refrigeration and heating requirements are reduced, and constant and comfortable indoor climate conditions are provided for users.

Description

Technical Field

[0001] The present invention belongs to the technical field of underground structure construction, and particularly relates to a construction method for jointly building a multi-layer urban underground complex and an urban bridge. Background Art

[0002] With the acceleration of the urbanization process, urban space resources are becoming increasingly tense. The joint construction of multi-layer urban underground complexes and urban bridges has become an important development direction for solving the problem of urban space utilization and enhancing the comprehensive carrying capacity of cities. However, under the existing technical conditions, the joint construction of multi-layer urban underground complexes and urban bridges faces many challenges and deficiencies.

[0003] In terms of the construction process, the existing technology usually adopts a method of constructing above-ground bridge components and underground complex structures in stages. This construction method requires process switching in different stages, resulting in a cumbersome construction process and obvious time waste. For example, after the construction of the underground complex structure is completed, it is necessary to wait for it to reach a certain strength before constructing the above-ground bridge components. During this period, the construction site is often idle, greatly reducing the project progress efficiency. Moreover, staged construction is also prone to connection problems at construction nodes, affecting the stability and safety of the overall structure.

[0004] In terms of structural load-bearing, the connection and load-bearing design of the above-ground bridge and the underground complex structure in the existing technology are not perfect. The above-ground bridge and the underground complex are often designed independently, lacking an effective collaborative load-bearing mechanism. When bearing vertical and horizontal loads, local stress concentration is likely to occur, increasing the risk of structural damage. Especially in the face of natural disasters such as earthquakes and floods, this structural system lacking collaborative load-bearing capacity is difficult to ensure the overall safety and stability. In addition, for the treatment of groundwater buoyancy, most of the existing technologies rely on large temporary support structures, which not only increase the construction cost and difficulty, but may also affect the long-term durability of the structure.

[0005] In terms of environmental regulation, the environmental control of existing underground complexes mainly relies on traditional mechanical refrigeration and heating equipment. These equipment have high energy consumption and large operating costs, and it is difficult to achieve precise balance of temperature and humidity in the underground space. In the project of jointly building an underground complex and an urban bridge, due to the complexity of the space structure, the traditional environmental regulation method is more difficult to meet the needs of users for a constant and comfortable indoor climate condition.

[0006] In terms of monitoring and regulation, the existing technologies for monitoring and regulating the overall load-bearing structure are relatively backward. There is a lack of a real-time and accurate monitoring system, making it impossible to timely obtain information such as structural strain and environmental parameters. When facing changes in structural loads and environmental parameters, feedback adjustment cannot be carried out in a timely manner, making it difficult to ensure that the structure and micro-environmental parameters are always in the best state. This not only affects the safety and service life of the structure, but also reduces the comfort of users.

[0007] In summary, the existing technologies have deficiencies such as low construction efficiency, insufficient structural load-bearing capacity, poor environmental regulation effect, and backward monitoring and regulation means in the co-construction of multi-layer urban underground complexes and urban bridges. Therefore, it is of great practical significance to develop an efficient, safe, comfortable and sustainable co-construction method for multi-layer urban underground complexes and urban bridges.

[0008] In response to this, the inventor proposes a co-construction method for multi-layer urban underground complexes and urban bridges to solve the above problems. Summary of the Invention

[0009] The purpose of the present invention is to provide a co-construction method for multi-layer urban underground complexes and urban bridges to solve the problems raised in the above background technology.

[0010] To achieve the above purpose, the present invention provides the following technical solutions: A co-construction method for multi-layer urban underground complexes and urban bridges includes the following steps: S1. Foundation pit enclosure and foundation replacement: Construct a nano-enhanced high-density concrete continuous wall in the predetermined construction area, and arrange prestressed anchor rods and adjustable buoyancy troughs for closed enclosure and soil grouting replacement to obtain a lightweight and high-load-bearing stable foundation; S2. Integrated pier-column and floor slab prefabrication: Prefabricate an array of hollow piers and cap beams, and uniformly pour them on the lightweight and high-load-bearing stable foundation, and pour the piers and the underground main roof into a whole to form a rigid load-bearing column array; S3. Microclimate regulation embedding: Embed heat exchange pipelines and water storage cooling cavities inside the underground complex space, and install phase change cold storage material segments to pre-adjust the temperature and humidity balance of the air flowing through the pipelines to obtain a constant and comfortable microclimate; S4. Synchronous hoisting of bridge deck girders: Segmentally hoist prefabricated bridge deck box girders on the solidified column array, and tension and connect them through adjustable prestressed steel cables to achieve the coordinated load-bearing balance of the bridge and the underground structure, and generate a coordinated load-bearing structure on the basis of the rigid load-bearing column array to obtain an overall load-bearing structure; S5. Dynamic monitoring and feedback regulation: Strain, temperature and humidity monitoring points are buried at key nodes of the overall load-bearing structure, and a PID closed-loop algorithm is used to drive the regulating device to dynamically feedback regulate the overall load-bearing structure, so as to maintain the self-balance of structural loads and environmental parameters and obtain the steady-state operation state after construction.

[0011] Preferably, a nano-enhanced high-density concrete continuous wall is constructed in a predetermined construction area, and prestressed anchor rods and adjustable buoyancy tanks are arranged for closed enclosure and soil grouting replacement to obtain a lightweight high-load-bearing stable foundation, including: constructing a continuous wall with nano-enhanced high-density concrete and high-strength fibers, the anchor rods are in the form of post-tensioned prestress, and the water level in the buoyancy tank is regulated in real time through an adjustable valve, and the buoyancy-anchor rod tension balance equation is used to compensate for the groundwater buoyancy.

[0012] Preferably, the buoyancy-anchor rod tension balance equation is: ; Ti: Tension of the i-th prestressed anchor rod (unit: kN); W struct : Self-weight of the foundation structure (unit: kN), including the weight of the continuous wall and the replaced soil; ρ w : Groundwater density, with a value of 1000 kg / m 3 ; V disp : Drainage volume below the drainage level of the enclosure structure and the replaced soil (unit: m³); g: Acceleration due to gravity, taking 9.81 m / s 2 ; ; where Lj is the length of the enclosure wall for each section j, unit: m; Hj is the drainage replacement depth, unit: m; Dj is the wall thickness, unit: m; This equation precisely cancels the groundwater buoyancy through the sum of the anchor rod tensions and the sum of the structural gravities, ensuring that the foundation pit and the precast pier columns - floor slabs have no net floating tendency under high groundwater levels and achieving the self-balance of the structural vertical displacement.

[0013] Preferably, the precast hollow pier columns and the cap beams are arranged in an array and are integrally cast on the lightweight high-load-bearing stable foundation, and the pier columns and the underground main roof are cast into a whole to form a rigid load-bearing column array, including: embedding a hydraulic leveling device and a prestressed cable channel in the hollow pier columns, the cap beams have an annular cross-section and are connected to the pier columns through transverse tie rods to achieve multi-directional load transfer.

[0014] Preferably, heat exchange pipelines and water storage cooling cavities are buried inside the underground complex space, and phase change cold storage material sections are embedded to pre-adjust the temperature and humidity balance of the air flowing through the pipelines to obtain a constant and comfortable microclimate, including: the heat exchange pipeline material is a high thermal conductivity metal composite pipe, and the surface of the water storage cooling cavity is coated with phase change cold storage microcapsules to enhance the air-water heat exchange efficiency and pre-adjust the temperature and humidity balance of the air flowing through the pipelines to obtain a constant and comfortable microclimate.

[0015] Preferably, precast bridge deck box girders are hoisted in sections on the already cured column array and tension-connected by adjustable prestressed steel cables to achieve the coordinated load-bearing balance between the bridge and the underground structure, and a coordinated load-bearing structure is generated on the basis of the rigid load-bearing column array to obtain an overall load-bearing structure, including: adjustable insert slots are reserved at the beam ends of the precast bridge deck box girders, fixed by self-locking anchor fittings after the steel cable tensioning, and the stress coordination between the bridge deck and the underground structure is realized through fine-tuning jacks during the suspension stage to obtain an overall load-bearing structure.

[0016] Preferably, strain, temperature, and humidity monitoring points are buried at the key nodes of the overall load-bearing structure, and a PID closed-loop algorithm is used to drive the regulating device to perform dynamic feedback regulation on the overall load-bearing structure to maintain the self-balance of the structural load and environmental parameters and obtain a steady-state operation state after construction, including: fiber optic strain gauges and digital temperature and humidity sensors are set at the monitoring points, the ventilation valve is an electric regulating butterfly valve, and the heating pipe is a buried electric heating conduit, and the load-bearing state and microenvironment parameters are balanced in real time through a closed-loop control algorithm; Preferably, the formula of the PID closed-loop algorithm is: ; where, u(t): the output of the actuator; e(t)=r(t)-y(t): the deviation value, equal to the difference between the target value r(t) and the real-time measured value y(t); Kp: the proportional gain, dimensionless; Ki: the integral gain, unit is s -1 ; Kd: the derivative gain, unit is s; : the integral of the deviation e(t) from the initial moment to the current moment t, accumulating the influence of historical deviations; : the derivative of the deviation e(t) with respect to time (rate of change), reflecting the deviation change trend; Through the comprehensive adjustment of the three items of proportional, integral, and derivative, the rapid response to structural strain and microclimate parameters, the elimination of static error, and the prediction of trends are realized. This algorithm can ensure that during the coordinated load-bearing of the bridge-underground complex and the microenvironment regulation process, the target load and the set values of temperature and humidity are always maintained, thereby improving the overall safety and comfort.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In the present invention, the above-ground bridge components and the underground complex structure are constructed synchronously, without the need to wait in stages and carry out secondary construction, effectively eliminating the process switching and time waste between construction nodes, and significantly improving the project progress efficiency. Through the integral casting of the pier column and the floor slab and the connection of the circular bearing platform beam, a unified load-bearing skeleton is formed, realizing the collaborative sharing of vertical and horizontal loads, reducing the risk of local stress concentration, and enhancing the overall seismic and anti-floating capabilities.

[0018] (2) In the present invention, a heat exchange and phase change energy storage device is arranged in the underground space to create a self-stabilizing temperature and humidity balance environment, reducing the demand for mechanical refrigeration and heating, and providing a constant and comfortable indoor climate condition for users. Through the combined action of post-tensioned anchor rods and adjustable buoyancy devices, a fine balance of groundwater buoyancy is achieved, without relying on large-scale temporary supports, reducing long-term maintenance investment and improving the structural durability. The strain and temperature and humidity real-time feedback drive the regulating device, which can automatically respond to environmental and load changes even without unattended operation, ensuring that the structural and micro-environment parameters are always in the best state. The modular prefabrication and precise replacement technology reduce the use of temporary support materials, and the microclimate regulation system reduces traditional energy consumption, meeting the concept of sustainable development. Description of the Drawings

[0019] Figure 1 It is a flow chart of the construction method for jointly building a multi-layer urban underground complex and an urban bridge according to the present invention. Detailed Embodiments

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] Embodiment 1: Please refer to Figure 1 As shown, the construction method for jointly building a multi-layer urban underground complex and an urban bridge includes the following steps: S1. Foundation pit enclosure and foundation replacement: Construct a nano-enhanced high-density concrete continuous wall in the predetermined construction area, and arrange prestressed anchor rods and adjustable buoyancy troughs for closed enclosure and soil grouting replacement to obtain a lightweight and high-load-bearing stable foundation; The continuous wall is constructed using nano-enhanced high-density concrete with high-strength fibers. The anchor rods are in the form of post-tensioned prestress, and the buoyancy trough can adjust the water level in the trough in real time through an adjustable valve, and compensate for the groundwater buoyancy through the buoyancy-anchor tension balance equation; The buoyancy-anchor tension balance equation is: ; Ti: Tension of the i-th prestressed anchor rod (unit: kN); W struct : Self-weight of the foundation structure (unit: kN), including the weight of the diaphragm wall and the replaced soil mass; ρ w : Density of groundwater, with a value of 1000 kg / m 3 ; V disp : Drainage volume below the drainage level of the retaining structure and the replaced soil mass (unit: m³); g: Acceleration due to gravity, taking 9.81 m / s 2 ; ; Wherein, Lj is the length of the retaining wall for each section j, unit: m; Hj is the drainage replacement depth, unit: m; Dj is the wall thickness, unit: m; This equation precisely cancels out the buoyancy of groundwater through the sum of the anchor rod tensions and the sum of the structural gravities, ensuring that the foundation pit and the precast pier-column - floor slab have no net floating tendency under high groundwater levels, and achieving self-balancing of the vertical displacement of the structure; S2. Integrated pier-column - floor slab precast: Precast hollow pier columns and a pile cap beam array, and uniformly pour them on the lightweight high-load stable foundation, casting the pier columns and the underground main roof into a whole to form a rigid load-bearing column array; Embed a hydraulic leveling device and a prestressed cable channel in the hollow pier column, and the pile cap beam adopts an annular cross-section and is connected to the pier column through a transverse tie rod to achieve multi-directional load transfer; S3. Microclimate regulation and embedding: Embed heat exchange pipelines and a water storage cooling cavity inside the underground complex space, and install phase change energy storage cooling material segments to pre-adjust the temperature and humidity balance of the air flowing through the pipelines to obtain a constant and comfortable microclimate; The heat exchange pipeline material is a high thermal conductivity metal composite pipe, and the surface of the water storage cooling cavity is coated with phase change energy storage cooling microcapsules to enhance the air-water heat exchange efficiency, pre-adjust the temperature and humidity balance of the air flowing through the pipelines, and obtain a constant and comfortable microclimate; S4. Synchronous hoisting of bridge deck girders: Segmentally hoist precast bridge deck box girders on the cured column array, and connect them through adjustable prestressed steel cables for tensioning to achieve the coordinated load-bearing and leveling of the bridge and the underground structure, generating a coordinated load-bearing structure on the basis of the rigid load-bearing column array to obtain an overall load-bearing structure; Reserve an adjustable insert notch at the beam end of the precast bridge deck box girder, fix it with a self-locking anchor after steel cable tensioning, and achieve stress coordination between the bridge deck and the underground structure through a fine-tuning jack during the suspension stage to obtain an overall load-bearing structure; S5. Dynamic Monitoring and Feedback Regulation: Strain, temperature, and humidity monitoring points are buried at the key nodes of the overall bearing structure. The PID closed-loop algorithm is used to drive the regulating device to perform dynamic feedback regulation on the overall bearing structure, so as to maintain the self-balance of structural load and environmental parameters and obtain the steady-state operation state after construction.

[0022] Optical fiber strain gauges and digital temperature and humidity sensors are set at the monitoring points. The ventilation valve is an electric regulating butterfly valve, and the heating pipe is a buried electric heating conduit. The bearing state and microenvironment parameters are balanced in real time through the closed-loop control algorithm. The formula of the PID closed-loop algorithm is: ; where, u(t): the output of the actuator; e(t)=r(t)-y(t): the deviation value, which is equal to the difference between the target value r(t) and the real-time measured value y(t); Kp: proportional gain, dimensionless; Ki: integral gain, with the unit of s -1 ; Kd: derivative gain, with the unit of s; : the integral of the deviation e(t) from the initial moment to the current moment t, accumulating the influence of historical deviations; : the derivative of the deviation e(t) with respect to time (rate of change), reflecting the change trend of the deviation; Through the comprehensive regulation of the proportional, integral, and derivative terms, rapid response to structural strain and microclimate parameters, elimination of static error, and prediction of trends are achieved. This algorithm can ensure that during the collaborative bearing of the bridge-underground complex and microenvironment regulation, the target load and temperature and humidity set values are always maintained, thereby improving the overall safety and comfort.

[0023] As can be seen from the above, the construction of the above-ground bridge components and the underground complex structure is carried out synchronously, without the need for phased waiting and secondary construction, effectively eliminating the process switching and time waste between construction nodes, and significantly improving the project progress efficiency.

[0024] Through the integral casting of the pier column and floor slab and the connection of the circular bearing platform beam, a unified load-bearing framework is formed to achieve the collaborative sharing of vertical and horizontal loads, reduce the risk of local stress concentration, and enhance the overall seismic and anti-floating capabilities.

[0025] Example 2: Soft Soil Area with High Groundwater Level (3 m) - Medium Temperature Microclimate Scenario Foundation Pit Enclosure and Foundation Replacement Continuous Wall: Thickness 1.2 m, Embedded Depth 12 m, Material: Nano-Reinforced High-Density Concrete (Compressive Strength 80 MPa).

[0026] Prestressed anchor rods: diameter φ 80 mm, spacing 3 m, a total of n = 40 roots.

[0027] Adjustable buoyancy tank volume: 50 m³, real-time feedback of the water level in the tank.

[0028] Data acquisition: The tension of the anchor rod is measured in real time by a tensiometer (accuracy ±1%); the groundwater level is recorded by a water level gauge (accuracy ±5 mm).

[0029] Calculation ;

[0030] Take the tension of each anchor rod Ti = 1,200 kN, the self-weight of the structure; W struct = 80 MPa × 1.2 m × 12 m × 1,000 kg / m 3 × g = 11,272 kN; ; Where, Lj is the length of the retaining wall for each section j, unit: m; Hj is the drainage replacement depth, unit: m; Dj is the wall thickness, unit: m; Drainage volume V disp = 50 m 3 , then the buoyancy Fb = 1,000 × 50 × 9.81 = 490.5 kN; The resultant force on the left side 40 × 1,200 + 11,272 = 59,272 kN is much greater than 490.5 kN; Verify that the structural safety redundancy factor is approximately equal to 120; The calculation formula for the safety redundancy factor SF is: ;

[0031] Where, SF is the safety redundancy factor, dimensionless, reflecting the ratio of the anti-floating ability to the buoyancy demand; Ti: The tension of the i-th prestressed anchor rod, unit: kN; W struct : The self-weight of the foundation structure, unit: kN, including the weight of the diaphragm wall and the replaced soil mass; ρ w : The density of groundwater, taking the value of 1,000 kg / m 3 ; V disp : The drainage volume below the drainage level of the retaining structure and the replaced soil mass, unit: m³; g: The acceleration due to gravity, taking 9.81 m / s 2 .

[0032] Integrated Pier - Floor Prefabrication Hollow Pier: Cross - section 2 m × 2 m, height 6 m, with embedded hydraulic leveling cylinders (stroke 50 mm, maximum thrust 2000 kN); the diameter of the cap beam D = 5 m.

[0033] Data Acquisition: The prefabrication accuracy of the pier is detected by three - dimensional laser scanning (accuracy ±2 mm); the compressive strength of the 24 - hour cured test block after pouring reaches 45 MPa.

[0034] Micro - climate Regulation Embedding Heat - exchange Pipeline: Spiral - shaped φ 50 mm copper pipe with a length of 200 m, buried depth 1.5 m; the volume of the water - storage cooling cavity is 20 m³, filled with PCM (phase - change temperature 22 °C, latent heat 180 kJ / kg).

[0035] Data Acquisition: The inlet and outlet air temperature and humidity are recorded every 5 minutes by digital temperature and humidity sensors (±0.2 °C / ±2%RH).

[0036] Effect: The initial indoor air is 30 °C / 80%RH, and after adjustment, it stabilizes at 22 ± 1 °C and 50 ± 5%RH.

[0037] Synchronous Hoisting of Bridge Deck Beams Box Girder: Span 30 m, single - beam weight 120 t, prefabricated off - site.

[0038] Prestressed Steel Cables: Diameter φ 36 mm, 4 cables are arranged per span, and the tensile force is 600 kN / cable.

[0039] Data Acquisition: The tensile force of the steel cable is fed back by a tension monitoring system (accuracy ±2%); the displacement sensors of the synchronous jacks (±1 mm) monitor the settlement of the beams and slabs.

[0040] Effect: After the live load is applied, the settlement ≤ 5 mm, the lateral displacement ≤ 3 mm, and the stress distribution between the bridge and the underground structure is uniform.

[0041] Dynamic Monitoring and Feedback Regulation Monitoring Points: A total of 20 fiber Bragg grating strain gauges and 10 sets of digital temperature and humidity sensors.

[0042] PID Parameters: Kp = 1.2, Ki = 0.05, Kd = 0.01.

[0043] Data Acquisition: Real - time acquisition at 1 Hz, calculating the stress, temperature and humidity deviation e(t) to drive the ventilation valve and electric heating tube.

[0044] Effect: Temperature set point at 22 °C, adjustment time lag ≤ 30 s, overshoot ≤ 2%; strain deviation controlled within ±50 με.

[0045] The effect comparison is shown in Table 1 below: Table 1

[0047] As can be seen from the above, by arranging heat exchange and phase change energy storage devices in the underground space, a self-stabilizing temperature and humidity balance environment can be created, reducing the demand for mechanical refrigeration and heating, and providing a constant and comfortable indoor climate condition for users.

[0048] Example 3: Sandy soil with high groundwater level (6 m) - low temperature microclimate scenario Foundation pit enclosure and foundation replacement Diaphragm wall: thickness 1.0 m, embedment depth 15 m, concrete strength 60 MPa; Anchor rod: φ 70 mm, spacing 2.5 m, a total of n = 60 roots; trough volume 80 m³; Water level 6 m, measured ρ w  V disp  g = 1000×80×9.81 = 784.8 kN; Each anchor rod Ti = 1000 kN, self-weight of the structure 15000 kN, margin: 60000 + 15000 is much greater than 784.8 kN.

[0049] Integrated pier-column – floor prefabrication Hollow pier-column 2.5×2.5 m, height 8 m; hydraulic cylinder stroke 80 mm; cap beam D = 6 m; 3D scanning accuracy ±1 mm; 28-day strength 50 MPa.

[0050] Microclimate regulation embedding Heat exchange pipeline: φ 60 mm copper pipe 300 m, water storage cavity 30 m³; PCM phase change at 18 °C, latent heat 200 kJ / kg; Initial 15 °C / 60%RH, adjusted to 18 ± 0.5 °C, 55 ± 3%RH.

[0051] Synchronous hoisting of bridge deck girders Box girder span 25 m, weight 100 t; prestressed steel cables 5 per span, 600 kN per root; settlement ≤ 4 mm; lateral movement ≤ 2 mm.

[0052] Dynamic monitoring and feedback control 30 strain gauges, 12 sets of temperature and humidity sensors; PID parameters: Kp=1.5, Ki=0.08, Kd=0.015; Time lag ≤ 25 s, overshoot ≤ 1.5%; strain deviation ±40 με.

[0053] The data comparison is shown in Table 2 below: Table 2

[0054] From the above, we can see that this scheme controls the foundation pit displacement to a few millimeters, and the safety redundancy factor is increased by nearly a hundred times; Microclimate regulation achieves high-precision temperature control within ±1°C; The amount of temporary support was significantly reduced by 65–70%; The settlement and displacement of the bridge-underground collaborative bearing system are significantly optimized, ensuring long-term operational safety and comfort.

[0055] As can be seen above, the combined action of post-tensioned anchors and adjustable buoyancy devices achieves a precise balance of groundwater buoyancy, eliminating the need for large temporary supports, reducing long-term maintenance costs, and improving structural durability. Real-time feedback from strain, temperature, and humidity drives the adjustment device, automatically responding to environmental and load changes even in unattended conditions, ensuring that structural and microenvironmental parameters are always optimal. Modular prefabrication and precise replacement techniques reduce the use of temporary support materials, and the microclimate control system reduces traditional energy consumption, aligning with the concept of sustainable development.

[0056] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. Construction method for jointly building a multi-layer urban underground complex and an urban bridge, characterized in that, It includes the following steps: S1. Foundation pit enclosure and foundation replacement: Construct a nano-enhanced high-density concrete continuous wall in the predetermined construction area, and arrange prestressed anchor rods and adjustable buoyancy tanks to enclose and grout and replace the soil mass to obtain a lightweight and high-load-bearing stable foundation; S2. Integrated pier-column and floor slab prefabrication: Prefabricate an array of hollow piers and pile caps, and uniformly pour them on the lightweight and high-load-bearing stable foundation, and pour the piers and the underground main body roof into a whole to form a rigid load-bearing column array; S3. Microclimate regulation and embedding: Embed heat exchange pipelines and water storage and cooling cavities inside the underground complex space, and install phase change cold storage material segments to pre-adjust the temperature and humidity balance of the air flowing through the pipelines to obtain a constant and comfortable microclimate; S4. Synchronous hoisting of bridge deck beams and slabs: Segmentally hoist prefabricated bridge deck box girders on the solidified column array, and tension and connect them through adjustable prestressed steel cables to achieve the coordinated load-bearing and leveling of the bridge and the underground structure, and generate a coordinated load-bearing structure on the basis of the rigid load-bearing column array to obtain an overall load-bearing structure; S5. Dynamic monitoring and feedback control: Install strain, temperature, and humidity monitoring points at the key nodes of the overall load-bearing structure, and use the PID closed-loop algorithm to drive the regulating device to perform dynamic feedback regulation on the overall load-bearing structure to maintain the self-balance of the structural load and environmental parameters and obtain the steady-state operation state after construction.

2. The construction method for jointly building a multi-layer urban underground complex and an urban bridge according to claim 1, characterized in that The construction of the nano-enhanced high-density concrete continuous wall in the predetermined construction area, and the arrangement of prestressed anchor rods and adjustable buoyancy tanks to enclose and grout and replace the soil mass to obtain a lightweight and high-load-bearing stable foundation includes: Using nano-enhanced high-density concrete with high-strength fibers to construct the continuous wall, the anchor rods are in the form of post-tensioned prestress, the buoyancy tank can adjust the water level in the tank in real time through an adjustable valve, and the buoyancy-anchor tension balance equation is used to compensate for the groundwater buoyancy.

3. The construction method of jointly building a multi-layer urban underground complex and an urban bridge according to claim 2, characterized in that, The buoyancy-anchor tension balance equation is: ； where Ti is the tension of the i-th prestressed anchor rod, unit: kN; W struct : Self-weight of the basic structure, unit: kN, including the weight of the diaphragm wall and the replaced soil mass; ρ w : Groundwater density, with a value of 1000 kg / m 3 ; V disp : The drained volume below the drainage level of the enclosure structure and the replaced soil mass, unit: m³; g: acceleration due to gravity, taken as 9.81 m / s 2 ; ； where Lj is the length of the retaining wall for each section j, unit: m; Hj is the drainage and replacement depth, unit: m; Dj is the wall thickness, unit: m.

4. The construction method for jointly building a multi-layer urban underground complex and an urban bridge according to claim 1, characterized in that, The prefabrication of the array of hollow piers and pile caps, and the uniform pouring on the lightweight and high-load-bearing stable foundation, and pouring the piers and the underground main body roof into a whole to form a rigid load-bearing column array includes: Embedding a hydraulic leveling device and a prestressed cable channel in the hollow pier, the pile cap has an annular cross-section and is connected to the pier through a transverse tie rod to achieve multi-directional load transfer.

5. The construction method for jointly building a multi-layer urban underground complex and an urban bridge according to claim 1, characterized in that, The embedding of heat exchange pipelines and water storage and cooling cavities inside the underground complex space, and the installation of phase change cold storage material segments to pre-adjust the temperature and humidity balance of the air flowing through the pipelines to obtain a constant and comfortable microclimate includes: The heat exchange pipeline material is a high-thermal-conductivity metal composite pipe, and the surface of the water storage and cooling cavity is coated with phase change cold storage microcapsules to enhance the air-water heat exchange efficiency.

6. The construction method for jointly building a multi-layer urban underground complex and an urban bridge according to claim 1, characterized in that, Segmentally hoist precast bridge deck box girders on the already cured column array and connect them by tensioning adjustable prestressed steel cables to achieve the coordinated load-bearing balance between the bridge and the underground structure, and generate a coordinated load-bearing structure on the basis of the rigid load-bearing column array to obtain an overall load-bearing structure, including: precast bridge deck box girders are reserved with adjustable insert notches at the beam ends, the steel cables are fixed by self-locking anchors after tensioning, and the stress coordination between the bridge deck and the underground structure is achieved through fine-tuning jacks during the suspension stage.

7. The construction method for jointly building a multi-layer urban underground complex and an urban bridge according to claim 1, characterized in that, Embed strain, temperature and humidity monitoring points at the key nodes of the overall load-bearing structure, adopt a PID closed-loop algorithm to drive the regulating device, and perform dynamic feedback regulation on the overall load-bearing structure to maintain the self-balance of the structural load and environmental parameters, and obtain the steady-state operation state after construction, including: fiber optic strain gauges and digital temperature and humidity sensors are set at the monitoring points, the ventilation valve is an electric regulating butterfly valve, the heating pipe is a buried electric heating conduit, and the load-bearing state and micro-environment parameters are balanced in real time through the closed-loop control algorithm.

8. The construction method for jointly building a multi-layer urban underground complex and an urban bridge according to claim 7, characterized in that, The formula of the PID closed-loop algorithm is: ； Among them, u(t): the output of the actuator; e(t)=r(t)-y(t): the deviation value, which is equal to the difference between the target value r(t) and the real-time measured value y(t); Kp: proportional gain, dimensionless; Ki: Integral gain, unit: s -1 ; Kd: derivative gain, unit is s; : The integral of the deviation e(t) from the initial time to the current time t, which accumulates the influence of historical deviations; : The derivative of the deviation e(t) with respect to time (rate of change), which reflects the trend of deviation change.

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