Zhang Xiangyuan

On December 1, 2013, the Tianjin-Qinhuangdao High-Speed Railway "Jin-Qin High-Speed Railway" was officially opened for operation, shouldering the important responsibility of passenger transport between Tianjin and Qinhuangdao. This little dragon running along the Bohai Sea has become the first major link for passenger railway serialization among Northeast China, North China, and East China regions, which is of great significance. However, at the beginning of the railway construction, the project faced serious geological environmental problems. Within Tianjin, due to multiple historical changes between sea and land, thick soft soil layers have been deposited since the late Holocene; secondly, due to extensive groundwater development and utilization, serious ground subsidence phenomena occurred along the route, coupled with other geological disasters, resulting in poor geological environmental conditions along the route. For this reason, geologists used the results of Tianjin urban geological surveys, combined with the query and retrieval, professional map generation, 3D geological structure model construction, and comprehensive evaluation functions provided by the "Tianjin 3D Visualization Urban Geological Information Management and Service System," to conduct 3D "CT scans" of the rock and soil properties at certain depths above and below the line, and conducted geological disaster risk assessment and scientific site selection, surveying, monitoring, treatment, and evaluation for specific geological environments. It can be said that the coupling of geological science and information technology promoted the smooth opening of the Jin-Qin High-Speed Railway. The official operation of this high-speed railway embodies the dedication of geology and information technology workers, and also becomes a microcosm of Tianjin urban geological survey results serving socio-economic construction.

Tianjin 3D Visualization Urban Geological Information Management and Service System

The "Tianjin 3D Visualization Urban Geological Information Management and Service System" is one of the important results of the "Tianjin Urban Geological Survey" project cooperated by the Ministry of Land and Resources and Tianjin City, completed by the Tianjin Institute of Geological Survey in December 2010. Based on comprehensively collecting and organizing geological data from nearly 50 years in Tianjin and the data results from the "Tianjin Urban Geological Survey" project, the project established the Tianjin urban geological database composed of multi-professional, multi-scale, and massive geological basic data according to relevant standards; and adopted both automatic and interactive modeling methods to establish multi-professional 3D geological structure models with attributes for Tianjin, achieving a "comprehensive health check" of underground rock and soil in Tianjin; facing various needs of government management, professional applications, and the general public, with professional analysis results, 3D geological structure models, and various basic geological information as the focus, based on the MapGIS platform, using network technology, database technology, and 3D visualization and virtual reality technology, the project developed a geological information management and service system, built a virtual reality exhibition hall, and constructed the Tianjin urban geological survey data center integrating urban geological data collection, management, sharing, and service, becoming a comprehensive information platform for integrating, displaying, serving, and sharing all geological achievement data in Tianjin City in the future.

Purposeful and Unique

In 2005, Tianjin became one of the six pilot cities for urban geological surveys nationwide, launching the Tianjin urban geological survey project. In the process of special information system construction, targeting Tianjin's urban geological characteristics, the project team closely focused on model modeling accuracy and comprehensive evaluation model construction, explored new paths, extensively solicited opinions from relevant users and experts, conducted in-depth technical mining, and on this basis established a multi-level 3D geological model construction method; combined with various mainstream geoscience evaluation methods, constructed a comprehensive evaluation module, formed a multi-category geoscience professional model library; keeping pace with information technology development, fully applied virtual reality technology to the 3D expression of geoscience information. So, compared to several other pilot cities, what specific innovations does Tianjin have in urban geological information system construction?

First is the adoption of multi-level 3D geological structure modeling methods to establish multi-professional 3D geological structure models. For engineering geological structure models, three levels are divided: engineering geological layers, sedimentary facies, and lithology. In the central urban area, first-level strata modeling is used to directly reflect engineering geological layers. In the Binhai core area, third-level modeling is used for more precise reflection of lithological characteristics. The hydrogeological 3D structure model is divided into four levels from coarse to fine, with 6 aquifer groups and 89 standard layers. Using these models, precise auxiliary decision-making information can be intuitively and realistically provided for engineering site selection and construction, emergency rescue, and other work in Tianjin.

Secondly, the establishment, customization, expansion, and management of comprehensive geological professional evaluation models were completed. Targeting the complex evaluation needs of various users for geological professionals, based on multiple mainstream geoscience evaluation theories and supported by mainstream information technology, a comprehensive evaluation module was constructed. Starting from the establishment and management of evaluation models, user-centered approach simplified the operation process of evaluation models, conveniently and quickly providing users with multi-professional evaluation models and management tools, allowing professional users to customize evaluation models or extract existing analysis and evaluation models from the model library for geoscience evaluation. Based on the hot demands of engineering geology, hydrogeology, agricultural geology, geothermal resources, and geological disasters serving economic and social development, a dynamically updatable comprehensive evaluation model library was constructed, which can then provide comprehensive and differentiated evaluation services for government, society, and professionals in a targeted manner.

The combination of virtual reality technology and geoscience 3D information is a trend in 3D expression of geological achievements. People's previous understanding of underground conditions was achieved through drilling. Now, combined with urban geological survey results, using virtual reality technology, 3D technology, and mathematical methods, understanding underground information has become easy. Using this key technology and urban geological survey results as data support, the project team established a multi-channel geoscience virtual reality exhibition hall for Tianjin. Various users can wear 3D glasses, select areas of interest, and interactively operate the 3D geological structure model through computers, freely roaming, excavating, sectioning, and analyzing in 3D, presenting underground lithological information to users from multiple angles and realistically. Previously professional and dull geological data has now become intuitive, vivid, and easy-to-understand 3D reality in the eyes of users. This "immersive" real experience gives users "wings to fly underground" and realizes the "earth-penetrating abilities of Tu Xing Sun."

The establishment of this exhibition hall provides users with a real, reliable, and accurate geoscience information platform for understanding underground geological information. Since 2010, the exhibition hall has received more than 300 Chinese and foreign guests, and in 2012 was officially approved by relevant Tianjin departments as a Tianjin science education base. With the vigorous development of our institute's science popularization work, the Tianjin 3D geological science exhibition hall will welcome more and more people from all walks of life. We will continue to improve and innovate in terms of professionalism, knowledgeability, science popularization, and interactivity, promoting geoscience popularization, actively promoting the popularization of geological survey results, and improving public geoscience literacy.

Providing Comprehensive Geological Information Services for Various Industries

Since its completion, the system has provided rich geological information services for urban geological planning and engineering site selection, agricultural industrial structure adjustment, geological disaster prevention and control, underground space utilization, and other aspects for government management, planners, and professionals in Tianjin.

Consultant for Urban Planning and Engineering Site Selection

In the expansion and reconstruction project of Tianjin West Station, a high-speed railway hub connecting Northeast, North, and East China, the Tianjin urban geological information management and service system provided services for engineering geological condition parameter calculation and comprehensive evaluation as well as 3D analysis of engineering geological structure. Detailed zoning, stratification, and grading evaluation of shallow strata within 60m in the area was conducted, suitable pile foundation evaluation for engineering construction was performed, and evaluation zoning maps were generated; based on long-term hydrological observation data and borehole groundwater data in the area, underground groundwater level burial conditions were understood, the impact of groundwater on underground engineering construction was comprehensively analyzed, and a groundwater (soil) corrosivity evaluation zoning model for engineering structures in the work area was established. Based on the corrosivity evaluation results, according to existing engineering examples and relevant specifications, groundwater corrosivity to reinforced concrete was evaluated. 3D stratum structure models were established based on borehole data, 3D stratum structure model cutting and foundation pit excavation earthwork volume calculations were performed.

Guardian of Agricultural Geological Environment

How is Tianjin's agricultural geological environment? How many suitable planting areas are there? What crops are suitable for planting? These questions can be answered using the information system. Based on system sampling and testing, comprehensive analysis of Tianjin's agricultural geological environmental characteristics was conducted, and according to the site geological environmental requirements for different crop growth, the comprehensive evaluation function of the information system was used to achieve comprehensive zoning of agricultural geological environment. Tianjin was divided into 16 suitable planting areas for agricultural products, including 1 suitable area for urban vegetables and cash crops, 4 suitable areas for forestry and fruit, 5 suitable areas for vegetables, and 6 suitable areas for grain and cotton. This achievement provides important scientific basis for Tianjin's characteristic and green agricultural product origin planning, vegetable base development, agricultural product safety assurance, and quality improvement.

In addition to often needing to understand underground geological information in engineering construction, surface soil fertility, pollution, and quality issues are also closely related to our lives. For example, how much harmful pollutants are contained in construction land soil is a matter of great concern to everyone. Using urban geological survey results combined with the information system, graphic and textual decision-making information is provided, dynamically drawing plane distribution maps of pollution elements in user-interested areas. This map is provided to planners, enabling them to intuitively understand the distribution of certain elements in construction land and make decisions.

Think Tank for Disaster Prevention and Avoidance

Ground subsidence is Tianjin's main geological disaster. Our geological survey results have also played a key role in preventing and controlling ground subsidence. Through annual ground subsidence monitoring sequence data, the system can perform 3D simulation of ground subsidence monitoring data changing over time, establish a 3D temporal perception model, which intuitively, dynamically, and vividly demonstrates the changes in ground subsidence in the central urban area and Binhai New Area (Tanggu) over time. Due to the adoption of subsidence control measures, the subsidence rate decreased from 80-100mm/a in the 1980s to 10-15mm/a today. Through such visual demonstrations, government subsidence control departments can take corresponding regulatory measures based on the range and severity of subsidence, slowing down the rate of ground subsidence.

In addition, through this system, not only can the cumulative subsidence over many years and recent subsidence rates be understood, but also future urban ground subsidence development trends can be predicted, and ground subsidence risk evaluation can be conducted at any time using the Tianjin urban geological basic database and the system's comprehensive evaluation model.

Good Helper for Underground Space Utilization

With urban development, various underground space projects including subways, municipal pipelines, underground garages, civil air defense facilities, and commercial facilities are becoming increasingly widespread, and the quality of geological conditions is one of the decisive factors determining whether related projects can proceed.

Using the information system with 3D geological data as support, excavation analysis of the land underfoot can be conducted, any 3D structural surface can be arbitrarily sectioned, a 3D foundation pit can be excavated, and even simulated engineering 3D tunnels can be automatically generated based on underground engineering routes. For example, at the beginning of the construction of Tianjin Metro Line 5, this system was used to simulate tunnel cutting, allowing planners to experience the environment in advance, roam through it, understand the lithological conditions of tunnel walls, and analyze the lithology, structure, and spatial conditions of excavated strata in real time, helping users solve geological problems in construction and providing basic support for scientific route selection during the engineering route planning stage, and providing relevant underground geological environmental information in metro company consultation reports.

Evaluator for Land Use and Consolidation

Land ecological suitability analysis involves reasonable planning and rational evaluation of land resources in urban areas, determining the reasonable scale of urban development and suitable industrial spatial layout. Based on comprehensively collecting basic geological, topographic, meteorological, hydrological, land use, urban planning and construction, environmental protection, and ecological environment data in the work area, the system can conduct comprehensive land suitability evaluation calculations, ultimately submitting relevant land use suitability evaluation maps and proposing land functional zoning planning suggestions. During the development and construction of Binhai New Area, this system was used to conduct comprehensive evaluation analysis of land suitability in Binhai New Area, forming consultation reports that received good reviews from relevant departments, providing strong scientific basis for land planning, urban construction, and other aspects.

Differentiated and Refined One-Stop Service is the Future Development Direction

Whether an information system can provide reliable services, the urban geological survey database is the soul. Since the system was built, to ensure data currency and service timeliness, based on various urban geological survey results and with support from Tianjin land and resources authorities, continuous data updates and maintenance have been conducted. Taking borehole data required for engineering construction as an example, so far, hundreds of thousands of borehole data have been entered, and in the future, it will exceed one million data points. The densification of borehole data will inevitably improve the accuracy of 3D models, thereby providing more refined services to users.

Differentiated one-stop service is the direction for system improvement. The information system is highly professional, making it a commonly used tool for geologists, but more importantly, it needs to serve the government and the general public. This social service needs to emphasize simplicity, speed, and comprehensiveness. This requires continuous system maintenance, further analysis and summarization of different user needs, summarizing required functions, developing functions that provide rapid, comprehensive, and effective differentiated services based on different users, achieving "one-stop," graphic and textual, accurate and reliable information services for engineering construction, emergency risk avoidance, underground space utilization, geothermal resource development, and so on.

According to information technology development, timely function expansion is the key to improving system services. While enhancing refinement and one-stop services, timely tracking of system problems and information technology development, fully considering the needs of various users, there are many future directions for effort. For example, during tunnel roaming, one's position can be located at any time; the realism of lithological display can be increased; in 3D model structure display, infinite zooming can be achieved, just like in 2D GIS, achieving slice services and zoom display, publishing 3D information to the Internet, allowing users to analyze based on provided information online, and so on.

Strengthening data compatibility and sharing and exchange is a trend. Currently, relevant departments and units of the China Geological Survey are formulating 3D geological model data exchange standards, standardizing 3D geological system data structures, model standards, and so on. This is a direction for improving the industrialization level of this information system, strengthening data sharing and exchange, and enhancing service capabilities.

Strengthening geological data informatization construction and social service capabilities is a requirement proposed by leaders at all levels on different occasions and a mission bestowed by the times on geologists. Therefore, we geological and information technology professionals will closely focus on Tianjin's socio-economic development construction and land and resources management needs, with support from government management departments, continuously update the urban geological survey results database, combine geoscience knowledge, apply advanced and mainstream GIS and other information technologies, continuously improve and build a more intelligent 3D geological information management and service system, increase the intensity of geological work serving society and economic development, narrow the distance between geological results and application departments and the general public, further expand urban geological service fields, and guard the Bohai Sea coast.

Author Introduction:

Zhang Xiangyuan, Professor-level Senior Engineer, Director of the Geomineral Information Center of Tianjin Institute of Geological Survey (Tianjin General Station for Geological Environment Monitoring). Currently engaged in hydrogeological and environmental geological surveys and research, geological disaster monitoring and early warning, and information system construction and development work.