CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefits of priority to Chinese Patent Application No. CN 2020100034145, entitled “Fire Test System and Method for Tunnel Structure Based on Real-Time Fusion of Numerical and Physical Spaces”, filed with CNIPA on Jan. 2, 2020, the contents of which are incorporated herein by reference in its entirety.

BACKGROUND

Field of Disclosure

The present disclosure relates to the technical field of tunnels and underground construction engineering, and in particular, to a fire test system and method for tunnel structure based on real-time fusion of numerical and physical spaces.

Description of Related Arts

Fire is the major threat affecting the safety operation of tunnels. Due to the closed space environment, tunnel fires are characterized by fast heating speed, long duration, and uneven temperature distribution, which result in a large quantity of heat being transferred to the tunnel lining structure and surrounding strata during the fire, forming an unsteady temperature field with great temperature difference. Thereby, uneven heat stress and deformation are gradually developed and accumulated in the shield segments, which eventually cause the explosive spalling of the concrete, the debonding of the protective layer, and the thermal degradation of exposed steel bars. The bearing capacity and reliability of the tunnel lining structure are thus significantly reduced.

With the development and progress of society, there are more and more tunnel projects characterized by ultra-long distance, large section, large buried depth, high water and earth pressure, and complex geological conditions. These tunnels have complex lining structures and harsh geological conditions, and the mechanical behavior and failure mechanisms of the tunnels under fire are more complex. Therefore, it is important to ensure the fire safety of the large tunnel structures that are subjected to complex water and earth pressure.

At present, the research methods for the thermo-mechanical coupling problems of large complex tunnel structures at high temperature mainly include solely numerical calculation method, full-scale fire test of shield segment and small-scale fire test of full-ring lining structures. In the traditional research on the thermo-mechanical coupling problem of large complex tunnel structures under complex geological conditions, there are some problems and deficiencies, including: (1) the traditional experimental research and methods cannot take the tunnel structure-stratum as a composite system to consider the fire characteristics; (2) the solely numerical simulation has many limitations, i.e., there are large deviations in the simulation of key issues such as the structure-soil contact, and detail construction of the structure; furthermore, due to the lack of background information and accumulation, the numerical simulation method cannot accurately reflect the real stress and deformation characteristics of the structure; (3) scale model test can hardly reflect the real fire response of the underground structures under complex geological conditions.

Therefore, as the tunnel structure is developing rapidly towards “longer, larger and deeper”, the equipment capacity cannot satisfy the growing demand for full-scale tests. There is a huge gap between the available research tools and the needs. Therefore, a new method is needed to solve the above-mentioned problems.

SUMMARY

The present disclosure provides a fire test system and method for tunnel structure based on real-time fusion of numerical and physical spaces. Through the real-time interaction of the numerical and physical spaces and the, the holographic information acquisition of the real high temperature mechanical characteristics of the entire large tunnel structure system (structure and its surrounding stratum environment) and the entire fire process is realized.

The present disclosure provides a fire test system for tunnel structure based on real-time fusion of numerical and physical spaces. The fire test system includes:

a physical test unit, to perform a holographic fire test on a plurality of typical components in a tunnel structure system in a physical space, to obtain holographic characteristic parameter data of the components;

a numerical analysis unit, to establish a full-scale numerical model of the tunnel structure system in a numerical space, to obtain multi-field coupling boundary data of the typical components; and

a fusion control unit, to control and adjust a multi-field coupling boundary of the physical space according to the multi-field coupling boundary data, and to update and adjust an input parameter of the numerical space according to the holographic characteristic parameter data.

In an embodiment, the physical test unit includes a fire thermal environment simulation subsystem, a multi-field coupling boundary loading subsystem, and a holographic data acquisition subsystem.

In an embodiment, the fire thermal environment simulation subsystem includes a furnace, a burner, a temperature control box, an air supply device, and a gas supply device.

In an embodiment, the gas supply device includes a liquefied gas cylinder and a gasification apparatus.

In an embodiment, the holographic characteristic parameters include macroscopical mechanical parameters, multi-field characteristic parameters, and multi-scale image information.

In an embodiment, the holographic characteristic parameters include the temperature in the furnace, the temperature distribution inside the segment, the displacement of the segment, the opening angle of the joint, the moisture content of the segment, the ultrasonic wave velocity of the segment, the infrared thermogram of the segment, the crack propagation, and the bursting exfoliation.

In an embodiment, the multi-field coupling boundary data includes the thermal-mechanical-water-vapor multi-field coupling boundary data.

In an embodiment, the full-scale numerical model of the tunnel structure system includes a tunnel structure model and a tunnel-surrounding water and soil model.

In an embodiment, the typical components include a standard block, a capping block, a joint, and a water stop strip.

In an embodiment, the numerical analysis unit obtains the multi-field coupling boundary data of the typical components through lightweight calculation.

In an embodiment, the physical test unit performs a holographic fire test on the plurality of typical components in the tunnel structure system in the physical space, to obtain the time-dependent holographic characteristic parameter data of the components;

the numerical analysis unit establishes a full-scale numerical model of the tunnel structure system in the numerical space, to obtain the time-dependent multi-field coupling boundary data of the typical components;

the fusion control unit controls and adjusts the multi-field coupling boundary of the physical space according to the obtained multi-field coupling boundary data, and updates and adjusts the input parameters of the numerical space in real time according to the obtained holographic characteristic parameter data.

The present disclosure further provides a fire test method for tunnel structure based on real-time fusion of numerical and physical spaces. The fire test method includes:

obtaining the holographic characteristic parameter data of the components by performing a holographic fire test on a plurality of typical components in the tunnel structure system in the physical space;

obtaining the multi-field coupling boundary data of the typical components by establishing a full-scale numerical model of the tunnel structure system in the numerical space; and

controlling and adjusting the multi-field coupling boundary of the physical space according to the multi-field coupling boundary data, and updating and adjusting the input parameters in the numerical space according to the holographic characteristic parameter data.

In an embodiment, the holographic characteristic parameters include a macroscopical mechanical parameter, a multi-field characteristic parameter, and image information.

In an embodiment, the holographic characteristic parameters include the temperature in the furnace, the temperature distribution inside the segment, the displacement of the segment, the opening angle of the joint, the moisture content of the segment, the ultrasonic wave velocity of the segment, the infrared thermogram of the segment, the crack propagation, and the bursting exfoliation.

In an embodiment, the operation of obtaining the multi-field coupling boundary data of the typical components by establishing the full-scale numerical model of the tunnel structure system in the numerical space includes: obtaining the multi-field coupling boundary data of the typical components through lightweight calculation by establishing a full-scale numerical model of the tunnel structure system in the numerical space.

In an embodiment, the typical components include a standard block, a capping block, a joint, and a water stop strip.

In an embodiment, the multi-field coupling boundary data includes the thermal-mechanical-water-vapor multi-field coupling boundary data.

In an embodiment, the full-scale numerical model of the tunnel structure system includes a tunnel structure model and a tunnel-surrounding water and soil model.

The fire test system and method of the present disclosure break through the limitations of traditional component test and numerical simulation, creatively integrate the physical space and the numerical space, and can fully reflect the real fire response of the large complex tunnel system under the coupling effect of the fire field.

The fire test system and method for tunnel structure based on real-time fusion of numerical and physical spaces according to the present disclosure can reflect the progressive failure mechanism of the tunnel structure as a discontinuous and hyperstatic system including multiple segments, and can reflect the mechanical characteristics, failure modes, and interaction with the stratum at the level of the structural system.

The fire test system and method for tunnel structure based on real-time fusion of numerical and physical spaces according to the present disclosure can provide theoretical foundation and technical support for solving the fire safety problem of subways and river-crossing and sea-crossing tunnel lining structures in complex environments.

