Keywords

1 Introduction

Around the world, with manufacturing development strategies put forward by many countries such as Made in China 2025, German Industry 4.0 and American Industrial Internet, intelligent manufacturing has become a common trend and goal of global manufacturing development [1,2,3]. How to realize the mapping and integration of physical world and virtual world is one of the crucial obstacles in the field of intelligent manufacturing at home and abroad. As a key technology to solve the problem of the integration of physical world and virtual world in the process of intelligent manufacturing, digital twin has been widely concerned and studied in recent years, and has been gradually applied in some fields.

The idea of digital twin was first proposed by Professor Michael Grieves [4]. For the concept of virtual digital expression, it was named as “mirror space model” and “information mirror model” at first, and then evolved into the term “digital twin” in 2011. NASA was the first to propose the use of digital twin technology. By building a virtual aircraft model that is the same as the real aircraft, the flight state of the real aircraft can be accurately simulated to assist the pilot to make correct decisions [5, 6]. Since then, the concept of digital twinning has been taken seriously and popularized in the aviation industry.

During the continuous development of the concept of digital twin, Thomas introduced the theoretical research of real-time data acquisition based on digital twin [7]. Wang defined the man-machine cooperation framework system based on digital twin technology, and developed the man-machine co assembly system [8]. Liu and others proposed the research on digital twin modeling methods in their respective fields based on digital twin technology [9]. David studied the use of digital twin technology to enhance the level of disaster management [10]. During the COVID-19 pandemic, the Central South Architectural Design Institute used digital twin technology to plan and design the world-famous Wuhan Raytheon hospital, which help the hospital quickly put into operation.

In terms of digital twin city construction, it is in the early stage of construction and has made a certain contribution to urban decision-making, but many applications are relatively macro. Specifically in the field of civil engineering, a lot of research on digital twin is basically still in the theoretical research stage, most of them only solve local details, and there is a big gap compared with satellite, automobile, aircraft and other fields. Subdivided into the field of geotechnical engineering, the research is still a “new territory”, “no man's land”.

By introducing digital twin technology into the field of geotechnical engineering, we will focus on the construction of geotechnical engineering digital twin model, promote the professional application of geotechnical digital twin, and explore a new geotechnical engineering digital construction path and practice mode. However, there are still a lot of careful work to be carried out, but also need theoretical innovation and technical breakthrough. Therefore, this paper puts forward and defines the digital twin model of geotechnical engineering, describes the connotation of the digital twin model, studies the system structure of the digital twin model of geotechnical engineering, further builds the integrated model of geotechnical engineering, develops the simulation and analysis module of geotechnical engineering digital twin, and preliminarily forms the digital twin model of geotechnical engineering.

2 Definition and Connotation of Digital Twin Model in Geotechnical Engineering

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At present, the research on geotechnical engineering digital twin model is in the conceptual stage, lack of systematic definition and description. Considering the characteristics of geotechnical engineering, based on the concept and evolution process of digital twin, this paper gives the definition of geotechnical engineering digital twin model: use digital technology to describe and express the object characteristics, construction process, and real-time status of geotechnical engineering physical entities, so as to form a multi-scale, interactive and dynamic simulation virtual model (Digital twin body) accurately mapped with the objective geotechnical physical entities (completely corresponding) in the real world, which will be used to simulate and predict the state in the whole life cycle of geotechnical engineering.

Through the definition of geotechnical digital twin model, we can further analyze the connotation of digital twin model: (1) geotechnical engineering digital twin model is a virtual model of the physical entity of geotechnical engineering project in the real world, which can store all kinds of data and information in the whole life cycle of geotechnical engineering project. (2) Considering that the engineering geological body is naturally formed and has certain concealment, the geological information will be updated frequently with the progress of geotechnical engineering projects, so the geotechnical digital twin model needs to be constantly updated and interacted with the physical entities of geotechnical engineering projects. (3) There are multi-scale problems in the process of simulating the physical entity of geotechnical engineering projects. In the process of simulating geotechnical engineering for different purposes (such as visualization, computability, etc.), we need to extract different information from the digital twin model. (4) We can simulate and predict the possible status of geotechnical engineering projects in the specific construction process, and take measures in advance to ensure the progress of the projects.

The digital twin model of geotechnical engineering is formed in the stage of geotechnical engineering investigation and design. The three-dimensional information model constructed based on the actual survey data and design data forms the basis of the digital twin model of geotechnical engineering, which is further applied in the whole life cycle stage of geotechnical engineering projects. Digital twin model is not only the expression of geometric shape of geotechnical engineering model, but also can contain various semantic information of geotechnical engineering object and reflect some mechanical properties of geotechnical engineering object. Through the real-time interaction with the data and information of the construction site, the accuracy of the digital twin model of geotechnical engineering can be continuously improved. By the dynamic display of geotechnical engineering project, the real-time change of state in the life cycle process is simulated, and the possible state of actual geotechnical engineering is predicted.

3 Architecture of Digital Twin Model in Geotechnical Engineering

In order to construct the digital twin model of geotechnical engineering, it is necessary to build the underlying architecture based on the digital twin model to store and express the digital twin model. Then, the multi-source data of geotechnical engineering need to be standardized and systematized. For engineering geological body and engineering structure object, parameterization and digitalization techniques are used to build 3D information model respectively. On the basis of 3D information model and unified data standard, the integration of multiple models is realized. It is necessary to use the IOT technology to map the model to the geotechnical engineering physical entity, so as to ensure the high simulation of the digital twin model and physical entity. Further, in combination with the needs of specific geotechnical engineering projects, we can combine numerical simulation, big data, augmented reality, cloud computing, lightweight and other technologies to carry out model expression, simulation, intelligent prediction and decision-making assistance for digital twin models.

The architecture of digital twin model in geotechnical engineering is described from three aspects: underlying architecture, method system and application requirements (Fig. 1).

Fig. 1.
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Digital twin model architecture

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3.1 Underlying Architecture

In order to realize the top-level design of geotechnical engineering digital twin model theory, it is necessary to further define the internal data structure of the model object, organize the internal spatial data relations of the model object, form a clear hierarchy structure inside the model object, and complete the description of geotechnical engineering digital twin model. The data model for digital twin model of geotechnical engineering should abide by the following principles:

  • Applicability: the model adopts a unified data structure, which can not only describe the data characteristics of geological body and structural body, but also describe the geometric network relationship within the entity.

  • Universality: it can not only build geological body and structure model, but also meet the needs of geotechnical mechanical analysis.

  • Consistency: the data model supports Boolean operation analysis of engineering geological body and engineering structure model, and ensures the geometric topology consistency of the two models at the location of the common contact surface after operation.

  • Compatibility: data structure can be easily converted with other data structures.

3.2 Method System

  • Model construction: develop 3D geological modeling method for engineering geological body. Aiming at the engineering structure, the existing BIM software is used to develop the engineering structure component library and parametric component modeling method.

  • Data fusion: based on the unified data standard, the integration of engineering geological body model and engineering structure model is realized.

  • Simulation analysis: Dynamic loading of construction progress and time information, the simulation method of dynamic construction is established. Combined with mechanical parameters, the information model can be calculated, and the simulation analysis technology for geotechnical engineering digital twin model is formed.

4 Data Integrating and Sharing Mechanism of Digital Twin Model Based on Bim

Considering that IFC (Industry Foundation Classes) are extensible and unified data formats published by buildingSMART International for defining BIM models, so we exchange and share BIM model information and data based on IFC standard. By analyzing the existing IFC Standard Framework system, the IFC Standard expansion mechanism is studied.

According to the geotechnical engineering characteristics, aiming at the engineering structure and engineering geological object, the fusion mechanism of geotechnical information model based on IFC Standard is developed, and the basic data system of geotechnical digital twin model based on IFC Standard is formed.

5 Modeling and Integration of Digital Twin Model in Geotechnical Engineering

According to the borehole information, the interface information of each borehole stratum can be obtained. The DEM method is used to interpolate each formation interface, and the depth of each layer of borehole is used to calculate the formation layer. By intersecting each layer, topological relationship is re-established, and the upper and lower layers are formed. The intersecting strata are intersected to form a 3D geological model.

Based on BIM technology, considering the structural component characteristics of different types of engineering, the structural component families of various types of geotechnical engineering are generated through parametric modeling method. On this basis, the structural component library of geotechnical engineering is formed. Using geotechnical structural components, according to geotechnical engineering construction technology and construction method, the assembly technology of geotechnical structural components is developed, and a set of parameterized modeling method of geotechnical structural components based on BIM technology is established. Based on the above methods, various BIM models of geotechnical engineering constructed are shown in the Fig. 2.

Fig. 2.
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BIM model of geotechnical engineering

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6 Simulation Analysis Technology for Geotechnical Engineering Digital Twin

In order to break through the defect that the information model of geotechnical engineering has not played a full role for a long time, we developed the simulation and analysis module of geotechnical engineering digital twin based on the construction and integration module of geotechnical engineering digital twin model.

Based on the integrated model of geological body and structural body, the grid generation technology of BIM model for numerical calculation is developed, and the implementation method of numerical calculation function is formed. The geological model cutting program for construction process is developed, and the construction dynamic simulation method based on BIM Technology is constructed. From the two aspects of numerical analysis and construction simulation, the application research of geotechnical engineering digital twin model is promoted, and the simulation analysis technology for geotechnical engineering digital twin is established to make the geotechnical engineering digital twin model “both beautiful and useful”.

Based on the digital twin model theory of geotechnical engineering, combined with data standards, modeling methods and simulation analysis, the preliminary construction of digital twin model of geotechnical engineering is shown in Fig. 3.

Fig. 3.
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The preliminary construction of digital twin model of geotechnical engineering

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7 Conclusion

In this paper, digital twin technology is introduced into geotechnical engineering, and we have preliminarily established the geotechnical engineering digital twin model. By describing the definition, connotation and system structure of geotechnical digital twin model, the theoretical basis of geotechnical digital twin model is formed. The basic data system of geotechnical engineering digital twin model based on IFC standard is formed, which promotes the data fusion of information model built on BIM. Supported by BIM technology, we have formed the key modeling technology of digital twin. Driven by mechanical calculation and analysis, the data conversion and information exchange between BIM software and geotechnical engineering general numerical analysis software are realized. In order to realize the synchronization of virtual and real, the dynamic construction simulation of geotechnical excavation and structural application is realized, and the key technology of digital twin modeling and simulation in geotechnical engineering is formed. The research in this paper lays a solid foundation for the preliminary construction of digital twin model in geotechnical engineering, which promotes the popularization of digital twin technology in geotechnical engineering and helps the development of geotechnical engineering informatization and digitization.