Safety Early Warning System for Subway Tunnel Shield Construction and Its Application Method

Abstract

This invention discloses a safety early warning system for subway tunnel shield construction and its usage method. The system includes a shield machine data acquisition terminal, a settlement acquisition terminal, a groundwater level acquisition terminal, a gas concentration acquisition terminal, a gateway, a system server, and a remote mobile terminal. The shield machine data acquisition terminal collects real-time shield machine status data; the settlement acquisition terminal collects real-time settlement data of the ground surface, pipelines, and buildings; the groundwater level acquisition terminal collects real-time groundwater level data; and the gas concentration acquisition terminal collects real-time underground gas and oxygen concentration data. The system server, based on risk assessment rules, takes measures to adjust the shield machine cutters, reinforce the tunnel, implement drainage, grouting, and ventilation, and transmits these measures to the on-site construction manager via the gateway and remote mobile terminal. The advantage of this invention is that it provides safety monitoring of the shield construction process from multiple dimensions, achieving lean management of the shield machine status, geological structure assessment, and construction environment during shield construction.

Description

Technical Field

[0001] This invention relates to the field of shield tunneling technology, and in particular to a safety early warning system for shield tunneling in subway tunnels and its application method. Background Technology

[0002] In recent years, my country's urban rail transit engineering has developed rapidly, especially in major central cities, where the scale of operation and construction has grown rapidly. By the end of 2023, the total length of urban rail transit lines under construction in China reached 6,350.55 kilometers, and the total length of 308 operating lines reached 11,232.65 kilometers, ranking first in the world in terms of overall scale. However, due to the large scale of construction and operation, there are more and more cases of construction crossing or adjacent to existing lines, and the situation is becoming increasingly complex. Problems such as different types of new and old building complexes, complex geological environments, numerous underground pipelines, high construction risks, and difficulties in deformation control are becoming increasingly prominent. How to implement a real-time intelligent safety monitoring system in subway tunnel construction has become a key issue for the safety of subway shield tunneling construction.

[0003] With the development of science and technology, tunnel boring machine (TBM) construction has also seen the emergence of automated monitoring methods based on artificial intelligence technology. For example, Chinese patent CN117935507A discloses a real-time early warning system and method for TBM construction. This system uses Ethernet-connected devices to monitor the data status of sensors inside the TBM to prevent overload. It also uses ground-penetrating radar and rock detectors to detect geological structures and prevent geological disasters, and monitors soil deformation to prevent environmental risks. However, how to effectively utilize the TBM's working status data to predict geological changes during tunneling, adjust the cutterhead to reduce mechanical damage, monitor risk factors such as TBM tunneling, geological settlement, groundwater level, and gas concentration, introduce risk assessment levels, and provide real-time risk control measures to TBM construction site managers are urgent technical problems that need to be solved. Summary of the Invention

[0004] In view of this, the present invention proposes a safety early warning system for subway tunnel shield construction and its usage method, in order to solve the problem of lean management of shield safety in existing shield construction, including real-time monitoring of shield machine excavation, settlement, groundwater level, gas and oxygen concentration, risk assessment, and real-time implementation of corresponding control measures.

[0005] The technical solution of the present invention is implemented as follows: On the one hand, the present invention provides a safety early warning system for subway tunnel shield construction, which includes a shield machine data acquisition terminal, a settlement acquisition terminal, a groundwater level acquisition terminal, a gas concentration acquisition terminal, a gateway, a system server, and a remote mobile terminal.

[0006] The shield machine data acquisition terminal is installed in the shield machine PLC control system and connected to the gateway LoRa network. As a Modbus master station, it reads the real-time total thrust, cutterhead torque, tunneling speed, penetration depth and average earth pressure of the shield machine during construction and sends them to the gateway.

[0007] The settlement acquisition terminal is installed on the ground surface, pipelines and buildings, and connected to the gateway LoRa network to collect settlement data of the ground surface, pipelines and buildings in real time and send it to the gateway.

[0008] The groundwater level acquisition terminal is installed on the top of the water level hole buried in the soil above the shield tunnel and is connected to the gateway LoRa network to collect groundwater level height data in real time and send it to the gateway.

[0009] The gas concentration acquisition terminal is installed inside the shield tunnel and connected to the gateway LoRa network. It is used to collect real-time data on methane and oxygen concentrations in the tunnel and send it to the gateway.

[0010] The gateway is installed at the tunnel entrance and is used for switching between LoRa and 5G protocols.

[0011] The system server is connected to the gateway 5G network and is used to receive data from the tunnel boring machine data acquisition terminal, settlement acquisition terminal, groundwater level acquisition terminal and gas concentration acquisition terminal sent by the gateway. It determines the risk level according to the risk assessment rules and introduces risk control measures, which are then sent to the remote mobile terminal through the gateway.

[0012] The remote mobile terminal displays the risk level and risk control measures to the on-site construction manager, guiding the on-site construction.

[0013] Preferably, the tunnel boring machine data acquisition terminal includes a TTL to 485 module, an MCU controller, and a LoRa module;

[0014] The TTL to 485 module is connected to the TTL serial port of the MCU controller. It is used to convert the Modbus master station command sent by the MCU controller from TTL serial port signal to 485 signal and send it to the PLC slave station. The PLC data received from the PLC slave station is converted from 485 signal to TTL serial port signal and sent to the MCU controller.

[0015] The MCU controller is connected to the LoRa module via a TTL serial port and is used to transmit data read by the MCU controller as a Modbus master through the LoRa module.

[0016] The 4G / 5G module is electrically connected to the MCU controller and is used to receive 4G / 5G signals and send the signals to the MCU controller.

[0017] The MCU controller is electrically connected to the LoRa module and is used by the MCU controller to send signals through the LoRa module.

[0018] Preferably, the settlement acquisition terminal includes a hydrostatic level, an MCU controller, and a LoRa module;

[0019] The hydrostatic level is connected to the AD port of the MCU controller, and is used to receive the hydrostatic level signal and send the signal to the MCU controller via the AD port in the form of 0-10V or 4-20mA;

[0020] The MCU controller is connected to the LoRa module's TTL serial port and is used to transmit the sedimentation data read by the MCU controller through the LoRa module.

[0021] Preferably, the groundwater level acquisition terminal includes a water level depth probe, an MCU controller, and a LoRa module;

[0022] The water level depth probe is connected to the AD port of the MCU controller to receive the water level depth probe signal and send the signal to the MCU controller via the AD port in the form of 0-10V or 4-20mA.

[0023] The MCU controller is connected to the LoRa module via a TTL serial port and is used to transmit the groundwater level depth data read by the MCU controller through the LoRa module.

[0024] Preferably, the gas concentration acquisition terminal includes a gas concentration probe, an oxygen concentration probe, an MCU controller, and a LoRa module;

[0025] The gas concentration probe is connected to the AD port of the MCU controller to receive the gas concentration probe signal and send the signal to the MCU controller via the AD port in the form of 0-10V or 4-20mA.

[0026] The oxygen concentration probe is connected to the AD port of the MCU controller to receive the oxygen concentration probe signal and send the signal to the MCU controller via the AD port in the form of 0-10V or 4-20mA.

[0027] The MCU controller is connected to the LoRa module via a TTL serial port and is used to transmit the gas concentration and oxygen concentration data read by the MCU controller through the LoRa module.

[0028] Preferably, the gateway includes a 4G / 5G module, an MCU controller, and a LoRa module;

[0029] The 4G / 5G module is connected to the USB port of the MCU controller for exchanging information between the 4G / 5G data signal and the MCU controller data signal.

[0030] The MCU controller is connected to the LoRa module's TTL serial port for exchanging information between the MCU controller's data signals and the LoRa data signals.

[0031] Preferably, the remote mobile terminal includes a tablet computer and a LoRa module;

[0032] The tablet computer is connected to the LoRa module's TTL serial port to receive LoRa module signals and display them on the tablet computer.

[0033] On the other hand, the present invention provides a method for using a safety early warning system for subway tunnel shield construction; including the following steps:

[0034] S1. The shield machine data acquisition terminal collects the real-time total thrust, cutterhead torque, cutterhead speed, tunneling speed, penetration depth and average earth pressure of the shield machine during construction and sends them to the system server via the gateway;

[0035] S2. The system server calculates the tunneling energy in real time according to the tunneling energy formula, inputs the geological identification model to identify the geological structure in front of the tunnel boring machine, determines the tunneling risk level according to different geological structures, and adjusts the corresponding cutters using the empirical formula for the number of cutters to prevent mechanical damage to the tunnel boring machine.

[0036] S3. The settlement acquisition terminal collects real-time settlement data of the ground surface, pipelines and buildings during the tunnel boring machine construction and sends it to the system server via the gateway;

[0037] S4. The system server determines the settlement risk level and sends recommendations for tunnel reinforcement measures based on the risk level to prevent ground collapse or damage to underground facilities;

[0038] S5. The groundwater level acquisition terminal collects real-time groundwater level data during tunnel boring machine construction and sends it to the system server via the gateway;

[0039] S6. The system server determines the risk level of the groundwater level and sends suggestions for drainage or grouting measures based on the risk level to prevent groundwater leakage or sudden water inrush accidents.

[0040] S7. The gas concentration acquisition terminal collects real-time gas concentration data in the tunnel during shield tunneling and sends it to the system server via the gateway.

[0041] S8. The system server determines the gas concentration risk level and sends ventilation measures based on the risk level to prevent deflagration accidents;

[0042] S9. The system server determines the risk level of oxygen concentration and sends ventilation measures according to the risk level to prevent suffocation accidents;

[0043] S10. The remote mobile terminal receiving system server displays the risk status to the on-site construction manager through the gateway, and guides on-site safe construction.

[0044] The subway tunnel shield construction safety early warning system and its usage method of the present invention have the following advantages over the prior art:

[0045] (1) A shield machine data acquisition terminal was designed to realize the real-time acquisition of shield machine status data. The geological identification model was used to analyze the geological structure in front of the shield machine in real time and determine the tunneling risk level.

[0046] (2) An empirical formula for the number of cutterhead tools was constructed, and the number of different tools was adjusted according to the tunneling risk level to prevent mechanical damage to the tunnel boring machine.

[0047] (3) Settlement acquisition terminal, groundwater level acquisition terminal and gas concentration acquisition terminal were designed, and risk levels of settlement, groundwater level, gas concentration and oxygen concentration were delineated. Corresponding control measures were introduced according to the risk levels, realizing lean management of shield tunneling construction safety. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a structural diagram of the subway tunnel shield construction safety early warning system of the present invention;

[0050] Figure 2 This is a structural diagram of the tunnel boring machine data acquisition terminal of the present invention;

[0051] Figure 3 This is a structural diagram of the sedimentation acquisition terminal of the present invention;

[0052] Figure 4 This is a structural diagram of the groundwater level acquisition terminal of the present invention;

[0053] Figure 5 This is a structural diagram of the gas concentration acquisition terminal of the present invention;

[0054] Figure 6 This is a diagram of the gateway structure of the present invention;

[0055] Figure 7 This is a structural diagram of the remote mobile terminal of the present invention;

[0056] Figure 8This is a flowchart illustrating the usage method of the subway tunnel shield construction safety early warning system of the present invention. Detailed Implementation

[0057] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0058] Example 1

[0059] like Figure 1-7 As shown, the subway tunnel shield construction safety early warning system of the present invention includes a shield machine data acquisition terminal, a settlement acquisition terminal, a groundwater level acquisition terminal, a gas concentration acquisition terminal, a gateway, a system server, and a remote mobile terminal.

[0060] The shield machine data acquisition terminal is installed in the shield machine PLC control system and connected to the gateway LoRa network. As a Modbus master station, it reads the real-time total thrust, cutterhead torque, tunneling speed, penetration depth and average earth pressure of the shield machine during construction and sends them to the gateway.

[0061] The settlement acquisition terminal is installed on the ground surface, pipelines and buildings, and connected to the gateway LoRa network to collect settlement data of the ground surface, pipelines and buildings in real time and send it to the gateway.

[0062] The groundwater level acquisition terminal is installed on the top of the water level hole buried in the soil above the shield tunnel and is connected to the gateway LoRa network to collect groundwater level height data in real time and send it to the gateway.

[0063] The gas concentration acquisition terminal is installed inside the shield tunnel and connected to the gateway LoRa network. It is used to collect real-time data on methane and oxygen concentrations in the tunnel and send them to the gateway.

[0064] The gateway is installed at the tunnel entrance and is used for switching between LoRa and 5G protocols.

[0065] The system server is connected to the gateway 5G network and is used to receive data from the tunnel boring machine data acquisition terminal, settlement acquisition terminal, groundwater level acquisition terminal and gas concentration acquisition terminal sent by the gateway. It determines the risk level according to the risk assessment rules and introduces risk control measures, which are then sent to the remote mobile terminal through the gateway.

[0066] The remote mobile terminal displays the risk level and risk control measures to the on-site construction manager, guiding the on-site construction.

[0067] This system utilizes shield machine data acquisition terminals, settlement acquisition terminals, groundwater level acquisition terminals, gas concentration acquisition terminals, gateways, system servers, and remote mobile terminals to implement a safety early warning system for subway tunnel shield construction. This system monitors the shield construction process from multiple dimensions, including shield machine excavation, settlement, groundwater level, gas concentration, and oxygen concentration. It determines the risk level and sends corresponding control measures to the construction site, achieving lean management of shield machine status, geological structure assessment, and the construction environment during shield construction. Through design, simulation, and verification, a modular product is formed, enabling rapid portability between different platforms and accelerating the product development process.

[0068] The shield machine data acquisition terminal includes a TTL to 485 converter, an MCU controller, and a LoRa module.

[0069] The TTL to 485 module is connected to the TTL serial port of the MCU controller. It is used to convert the Modbus master station command sent by the MCU controller from TTL serial port signal to 485 signal and send it to the PLC slave station. The PLC data received from the PLC slave station is converted from 485 signal to TTL serial port signal and sent to the MCU controller.

[0070] The MCU controller is connected to the LoRa module via a TTL serial port and is used to transmit data read by the MCU controller as a Modbus master through the LoRa module.

[0071] The settlement acquisition terminal includes a hydrostatic level, an MCU controller, and a LoRa module;

[0072] The hydrostatic level is connected to the AD port of the MCU controller, and is used to receive the hydrostatic level signal and send the signal to the MCU controller via the AD port in the form of 0-10V or 4-20mA;

[0073] The MCU controller is connected to the LoRa module's TTL serial port and is used to transmit the sedimentation data read by the MCU controller through the LoRa module.

[0074] The groundwater level acquisition terminal includes a water level depth probe, an MCU controller, and a LoRa module;

[0075] The water level depth probe is connected to the AD port of the MCU controller to receive the water level depth probe signal and send the signal to the MCU controller via the AD port in the form of 0-10V or 4-20mA.

[0076] The MCU controller is connected to the LoRa module via a TTL serial port and is used to transmit the groundwater level depth data read by the MCU controller through the LoRa module.

[0077] The gas concentration acquisition terminal includes a gas concentration probe, an oxygen concentration probe, an MCU controller, and a LoRa module;

[0078] The gas concentration probe is connected to the AD port of the MCU controller to receive the gas concentration probe signal and send the signal to the MCU controller via the AD port in the form of 0-10V or 4-20mA.

[0079] The oxygen concentration probe is connected to the AD port of the MCU controller to receive the oxygen concentration probe signal and send the signal to the MCU controller via the AD port in the form of 0-10V or 4-20mA.

[0080] The MCU controller is connected to the LoRa module's TTL serial port and is used to transmit the gas concentration data read by the MCU controller through the LoRa module.

[0081] The gateway includes a 4G / 5G module, an MCU controller, and a LoRa module;

[0082] The 4G / 5G module is connected to the USB port of the MCU controller for exchanging information between the 4G / 5G data signal and the MCU controller data signal.

[0083] The MCU controller is connected to the LoRa module's TTL serial port for exchanging information between the MCU controller's data signals and the LoRa data signals.

[0084] The remote mobile terminal includes a tablet computer and a LoRa module;

[0085] The tablet computer is connected to the LoRa module's TTL serial port to receive LoRa module signals and display them on the tablet computer.

[0086] The 4G / 5G module is implemented using Fibocom FG132, the LoRa module is implemented using Chengdu Ebitech E22-230T33S, and the MCU controller is STMicroelectronics STM32F407. The code was compiled using C language in Keil uVision 5 software.

[0087] The subway tunnel shield construction safety early warning system in this embodiment utilizes shield machine data acquisition terminals, settlement acquisition terminals, groundwater level acquisition terminals, gas concentration acquisition terminals, gateways, system servers, and remote mobile terminals to realize a subway tunnel shield construction safety early warning system. This system monitors the shield construction process from multiple dimensions, including shield machine excavation, settlement, groundwater level, and gas concentration, determines the risk level, and sends corresponding control measures to the construction site. This achieves lean management of shield machine status, geological structure assessment, and construction environment during shield construction. Through design, simulation, and verification, a modular product is formed, which can be quickly ported between different platforms, accelerating the product development process.

[0088] Example 2

[0089] This document provides a method for using a safety early warning system for subway tunnel shield construction, which employs the subway tunnel shield construction safety early warning system as described in Example 1, and includes the following steps:

[0090] S1. The shield machine data acquisition terminal collects the real-time total thrust, cutterhead torque, cutterhead speed, tunneling speed, penetration depth and average earth pressure of the shield machine during construction and sends them to the system server via the gateway;

[0091] S2. The system server calculates the tunneling energy in real time according to the tunneling energy formula, inputs the geological identification model to identify the geological structure in front of the tunnel boring machine, determines the tunneling risk level according to different geological structures, and adjusts the corresponding cutters using the empirical formula for the number of cutters to prevent mechanical damage to the tunnel boring machine.

[0092] S3. The settlement acquisition terminal collects real-time settlement data of the ground surface, pipelines and buildings during the tunnel boring machine construction and sends it to the system server via the gateway;

[0093] S4. The system server determines the settlement risk level and sends recommendations for tunnel reinforcement measures based on the risk level to prevent ground collapse or damage to underground facilities;

[0094] S5. The groundwater level acquisition terminal collects real-time groundwater level data during tunnel boring machine construction and sends it to the system server via the gateway;

[0095] S6. The system server determines the risk level of the groundwater level and sends suggestions for drainage or grouting measures based on the risk level to prevent groundwater leakage or sudden water inrush accidents.

[0096] S7. The gas concentration acquisition terminal collects real-time gas concentration data in the tunnel during shield tunneling and sends it to the system server via the gateway.

[0097] S8. The system server determines the gas concentration risk level and sends ventilation measures based on the risk level to prevent deflagration accidents;

[0098] S9. The system server determines the risk level of oxygen concentration and sends ventilation measures according to the risk level to prevent suffocation accidents;

[0099] S10. The remote mobile terminal receiving system server displays the risk status to the on-site construction manager through the gateway, and guides on-site safe construction.

[0100] Wherein, the tunneling specific energy formula is: Where SE represents tunneling specific energy, in kJ / m³. 3 F represents total thrust in N, v represents tunneling speed in mm / min, T represents cutterhead torque in kN·m, w represents cutterhead rotation speed in r / min, and R0 represents cutterhead excavation radius in m.

[0101] The geological identification model includes either the KNN algorithm model or the EWM-KNN algorithm model;

[0102] The geological structure includes one of the following: hard rock, relatively hard rock, soft rock, and isolated rock;

[0103] The tunneling risk level is determined based on the geological structure type; hard rock is classified as high risk, and moderately hard rock is classified as...

[0104] Integer operation, N0 represents the number of cutters (unit: piece), N1 represents the number of hobs (unit: piece), N represents the total number of cutters (unit: piece), SE represents the current tunneling specific energy (unit: kJ / m). 3 SE′ represents the average tunneling specific energy corresponding to hard rock, relatively hard rock, soft rock, and boulder geological structures, in kJ / m. 3 β represents an empirical coefficient, a dimensionless quantity, with values ​​ranging from [0, 30). Generally, β is 0 for hard rocks, (0, 10) for relatively hard rocks, (10, 20) for soft rocks, and (20, 30) for boulders.

[0105] The settlement risk level is determined by the ratio of the actual settlement height to the standard settlement height. When the ratio is less than 30%, it is considered low risk; when it is between 30% and 60%, it is considered medium risk; and when it is above 30%, it is considered high risk.

[0106] The risk level of groundwater level is determined by the ratio of the actual drop in water level to the theoretical standard drop in water level. When the ratio is less than 20%, it is considered low risk; when it is between 20% and 60%, it is considered medium risk; and when it is above 20%, it is considered high risk.

[0107] The gas concentration risk level is determined by the actual gas concentration. When the gas concentration is less than 0.1%, it is considered low risk; 0.1% to 0.2% is considered medium risk; and the rest are considered high risk.

[0108] The risk level of the oxygen concentration is determined by the actual oxygen concentration. When the oxygen concentration is between 20% and 23.5%, it is considered low risk, and the rest is considered high risk.

[0109] The KNN algorithm model and the EWM-KNN algorithm were compiled using Python 3.9 software.

[0110] like Figure 8 As shown, the shield machine data acquisition terminal collects shield machine status data in real time, the settlement acquisition terminal collects settlement data of the ground surface, pipelines and buildings in real time, the groundwater level acquisition terminal collects groundwater level data in real time, and the gas concentration acquisition terminal collects underground gas concentration data in real time. After these data are sent to the system server via the gateway, the system server takes measures to adjust the shield machine cutters, tunnel reinforcement, drainage, grouting and ventilation according to the risk assessment rules. The data is then transmitted to the on-site construction manager through the gateway and remote mobile terminal to guide the on-site construction.

[0111] The method of using the subway tunnel shield construction safety early warning system in this embodiment adopts a modular design approach. It uses shield machine data acquisition terminals, settlement acquisition terminals, groundwater level acquisition terminals, gas concentration acquisition terminals, gateways, system servers, and remote mobile terminals to realize the subway tunnel shield construction safety early warning system. The system monitors the shield construction process from multiple dimensions such as shield machine excavation, settlement, groundwater level, gas concentration, and oxygen concentration, determines the risk level, and sends corresponding control measures to the construction site, realizing lean management of shield machine status, geological structure determination, and construction environment during shield construction.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for using a safety early warning system for subway tunnel shield construction, characterized in that: Includes the following steps: S1. The shield machine data acquisition terminal collects the real-time total thrust, cutterhead torque, cutterhead speed, tunneling speed, penetration depth and average earth pressure of the shield machine during construction and sends them to the system server via the gateway; S2. The system server calculates the tunneling energy in real time according to the tunneling energy formula, inputs the geological identification model to identify the geological structure in front of the tunnel boring machine, determines the tunneling risk level according to different geological structures, and adjusts the corresponding cutters using the empirical formula for the number of cutters to prevent mechanical damage to the tunnel boring machine. S3. The settlement acquisition terminal collects real-time settlement data of the ground surface, pipelines and buildings during the tunnel boring machine construction and sends it to the system server via the gateway; S4. The system server determines the settlement risk level and sends recommendations for tunnel reinforcement measures based on the risk level to prevent ground collapse or damage to underground facilities; S5. The groundwater level acquisition terminal collects real-time groundwater level data during tunnel boring machine construction and sends it to the system server via the gateway; S6. The system server determines the risk level of the groundwater level and sends suggestions for drainage or grouting measures based on the risk level to prevent groundwater leakage or sudden water inrush accidents. S7. The gas concentration acquisition terminal collects real-time data on methane and oxygen concentrations in the tunnel during shield tunneling and sends it to the system server via the gateway. S8. The system server determines the gas concentration risk level and sends ventilation measures based on the risk level to prevent deflagration accidents; S9. The system server determines the oxygen concentration risk level and sends ventilation measures accordingly. Prevent suffocation accidents; S10. The remote mobile terminal receiving system server displays the risk status to the on-site construction manager via the gateway, guiding safe construction on site; The tunneling specific energy formula is: Where SE represents tunneling specific energy, in kJ / m³. 3 F represents total thrust in N, v represents tunneling speed in mm / min, T represents cutterhead torque in kN·m, w represents cutterhead rotation speed in r / min, and R0 represents cutterhead excavation radius in m. The geological identification model includes either the KNN algorithm model or the EWM-KNN algorithm model; The geological structure includes one of the following: hard rock, relatively hard rock, soft rock, and isolated rock; The tunneling risk level is determined based on the geological structure type: hard rock is considered high risk, relatively hard rock is considered medium risk, and soft rock and boulders are considered low risk. The empirical formula for the number of cutting tools is: N0≥0 and N0≤N, where [] denotes the floor function, N0 represents the number of cutters (unit: piece), N1 represents the number of hobbing cutters (unit: piece), N represents the total number of cutters (unit: piece), and SE represents the current tunneling specific energy (unit: kJ / m). 3 SE′ represents the average tunneling specific energy corresponding to hard rock, relatively hard rock, soft rock, and boulder geological structures, in kJ / m. 3 β represents an empirical coefficient, a dimensionless quantity, with values ​​ranging from [0, 30). Generally, β is 0 for hard rocks, (0, 10) for relatively hard rocks, (10, 20) for soft rocks, and (20, 30) for boulders.

2. The method of using the subway tunnel shield construction safety early warning system as described in claim 1, characterized in that: The settlement risk level is determined by the ratio of the actual settlement height to the standard settlement height. When the ratio is less than 30%, it is considered low risk; when it is between 30% and 60%, it is considered medium risk; and when it is above 30%, it is considered high risk. The risk level of groundwater level is determined by the ratio of the actual drop in water level to the theoretical standard drop in water level. When the ratio is less than 20%, it is considered low risk; when it is between 20% and 60%, it is considered medium risk; and when it is above 20%, it is considered high risk. The risk level of the gas concentration is determined by the actual gas concentration. When the gas concentration is less than 0.1%, it is considered low risk; 0.1% to 0.2% is considered medium risk; and the rest is considered high risk. The risk level of the oxygen concentration is determined by the actual oxygen concentration. When the oxygen concentration is between 20% and 23.5%, it is considered low risk, and the rest is considered high risk.

3. The method of using the subway tunnel shield construction safety early warning system according to claim 1 involves a subway tunnel shield construction safety early warning system, comprising a shield machine data acquisition terminal, a settlement acquisition terminal, a groundwater level acquisition terminal, a gas concentration acquisition terminal, a gateway, a system server, and a remote mobile terminal; characterized in that: The shield machine data acquisition terminal is installed in the shield machine PLC control system and connected to the gateway LoRa network. As a Modbus master station, it reads the real-time total thrust, cutterhead torque, tunneling speed, penetration depth and average earth pressure of the shield machine during construction and sends them to the gateway. The settlement acquisition terminal is installed on the ground surface, pipelines and buildings, and connected to the gateway LoRa network to collect settlement data of the ground surface, pipelines and buildings in real time and send it to the gateway. The groundwater level acquisition terminal is installed on the top of the water level hole buried in the soil above the shield tunnel and is connected to the gateway LoRa network to collect groundwater level height data in real time and send it to the gateway. The gas concentration acquisition terminal is installed inside the shield tunnel and connected to the gateway LoRa network. It is used to collect real-time data on methane and oxygen concentrations in the tunnel and send them to the gateway. The gateway is installed at the tunnel entrance and is used for switching between LoRa and 5G protocols. The system server is connected to the gateway 5G network and is used to receive data from the tunnel boring machine data acquisition terminal, settlement acquisition terminal, groundwater level acquisition terminal and gas concentration acquisition terminal sent by the gateway. It determines the risk level according to the risk assessment rules and introduces risk control measures, which are then sent to the remote mobile terminal through the gateway. The remote mobile terminal displays the risk level and risk control measures to the on-site construction manager, guiding the on-site construction.

4. The subway tunnel shield construction safety early warning system as described in claim 3, characterized in that: The tunnel boring machine data acquisition terminal includes a TTL to 485 module, an MCU controller, and a LoRa module; The TTL to 485 module is connected to the TTL serial port of the MCU controller. It is used to convert the Modbus master station command sent by the MCU controller from TTL serial port signal to 485 signal and send it to the PLC slave station. The PLC data received from the PLC slave station is converted from 485 signal to TTL serial port signal and sent to the MCU controller. The MCU controller is connected to the LoRa module via a TTL serial port and is used to transmit data read by the MCU controller as a Modbus master through the LoRa module.

5. The subway tunnel shield construction safety early warning system as described in claim 3, characterized in that: The settlement acquisition terminal includes a hydrostatic level, an MCU controller, and a LoRa module; The hydrostatic level is connected to the AD port of the MCU controller, and is used to receive the hydrostatic level signal and send the signal to the MCU controller via the AD port in the form of 0-10V or 4-20mA; The MCU controller is connected to the LoRa module's TTL serial port and is used to transmit the sedimentation data read by the MCU controller through the LoRa module.

6. The subway tunnel shield construction safety early warning system as described in claim 3, characterized in that: The groundwater level acquisition terminal includes a water level depth probe, an MCU controller, and a LoRa module; The water level depth probe is connected to the AD port of the MCU controller to receive the water level depth probe signal and send the signal to the MCU controller via the AD port in the form of 0-10V or 4-20mA. The MCU controller is connected to the LoRa module via a TTL serial port and is used to transmit the groundwater level depth data read by the MCU controller through the LoRa module.

7. The subway tunnel shield construction safety early warning system as described in claim 3, characterized in that: The gas concentration acquisition terminal includes a gas concentration probe, an oxygen concentration probe, an MCU controller, and a LoRa module; The gas concentration probe is connected to the AD port of the MCU controller to receive the gas concentration probe signal and send the signal to the MCU controller via the AD port in the form of 0-10V or 4-20mA. The oxygen concentration probe is connected to the AD port of the MCU controller to receive the oxygen concentration probe signal and send the signal to the MCU controller via the AD port in the form of 0-10V or 4-20mA. The MCU controller is connected to the LoRa module via a TTL serial port and is used to transmit the gas concentration and oxygen concentration data read by the MCU controller through the LoRa module.

8. The subway tunnel shield construction safety early warning system as described in claim 3, characterized in that: The gateway includes a 4G / 5G module, an MCU controller, and a LoRa module; The 4G / 5G module is connected to the USB port of the MCU controller for exchanging information between the 4G / 5G data signal and the MCU controller data signal. The MCU controller is connected to the LoRa module's TTL serial port for exchanging information between the MCU controller's data signals and the LoRa data signals.

9. The subway tunnel shield construction safety early warning system as described in claim 3, characterized in that: The remote mobile terminal includes a tablet computer and a LoRa module; The tablet computer is connected to the LoRa module's TTL serial port to receive LoRa module signals and display them on the tablet computer.

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