1. Content Overview
Ground fissure geological disasters have brought serious harm to engineering construction, social economy and sustainable development in my country and other countries around the world. Its disaster prevention and reduction is a global problem . With the support of the National Natural Science Foundation of China, the Ministry of Land and Resources, the China Geological Survey and local governments, Chang'an University undertook the National Natural Science Foundation of China's key projects "Genesis Mechanism of Ground Fissures and Continental Dynamics in the Fenwei Basin" and Land and Resources Survey There are more than ten scientific research projects including the project "Research on the Monitoring and Prevention of Ground Subsidence of Ground Fissures in the Fenwei Area" and the Xi'an Metro Science and Technology Special Project "Research on the Harm of Ground Fissures to Subway Engineering in Xi'an and Preventive and Control Measures". These projects take urban ground fissures as the research object. Combined with my country's current large-scale urban rail transit, high-speed railway and other major engineering construction, they carry out systematic and in-depth research on the major key scientific and technological issues that may be caused by ground fissures. In terms of comprehensive prevention and control technology of ground fissures, A number of original research results have been achieved:
1) Proposed technical methods for the prevention and control of ground fissure disasters in buildings (structures). The safe avoidance distance (Table 1), fortification width and safe thickness of the overlying soil layer for buildings with different foundation forms in ground fissure sites are proposed. The results have been incorporated into industry regulations, avoiding a large number of engineering construction disasters and saving a lot of construction work. The land use provides a model for ground fissure disaster reduction in international cities.
Table 1 Minimum avoidance distance of buildings at ground fissure sites Unit: m
2) Proposed key technologies for subway engineering to adapt to large deformation of ground fissures, successfully solving the problem of urban rail transit construction in my country Technical difficulties in preventing and controlling ground fissures in China. In view of the harm caused by ground fissures to subway tunnels, four tunnel structure forms were innovatively proposed to adapt to the deformation of ground fissures, such as segmented deformation joints, flexible joint connections, partially enlarged sections, and closed waterproof structures (Figures 1 to 3) and Structural fortification parameters, and through large-scale physical model tests and numerical simulations under various working conditions (Figure 4, Figure 5), the suitability and safety of the proposed structural measures have been verified, and have been applied to Xi'an subway engineering design and Under construction.
Figure 1 Structural measure plan for tunnel section joints
Figure 2 Waterproof structure plan
1—Structure; 2—Rubber board; 3—Polystyrene Rigid plastic foam; 4-rivets to ensure reliable fixation of rubber and lining;
5-2~3mm U-shaped thin steel plate; 6-high-density PE board; 7-Ω-type waterstop and supporting devices; 8 —Preset grouting holes
Figure 3 Large-scale model test of segmented tunnels
Figure 4 Large-scale physical model test
Figure 5 Under different working conditions Finite element numerical simulation
3) Proposed ground fissure disaster prevention technologies for high-speed railways, highways and underground pipeline projects. Through large-scale physical model tests and numerical simulation analysis (Figure 6 to Figure 9), it is found that the failure mode of the roadbed is bending torsion shear failure; the failure mode of the bridge is falling beam, dislocation and rigid torsion shear failure mode; the failure mode of the underground pipeline is end The failure mode is the upturned cantilever beam and the reverse bending elastic foundation beam failure mode. Proposed crack-resistant design plans for roads, bridges, and underground pipelines.
Figure 6 Subgrade deformation caused by ground cracks and treatment measures
Figure 7 Simulation of bridge deformation caused by ground cracks
Figure 8 Ground cracks and pipeline model test
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Figure 9 The intersection plan of Xi'an's underground pipe network and ground fissures
4) A comprehensive disaster reduction technology method for urban ground fissures has been formed. Among them, the optimized groundwater exploitation plan launched has effectively slowed down the activities of ground fissures in inland basins in loess areas of my country, and achieved rational development and utilization of groundwater based on the prevention and control of ground fissures (Figures 10 to 13).
Figure 10 Ground fissure subsidence disaster control model in Xi'an area
Figure 11 Water-soil coupled three-dimensional seepage simulation in Xi'an area
Figure 12 Groundwater extraction restriction plan after implementation Fracture activity rate slowdown curve
Figure 13 Groundwater recharge makes the tilted Big Wild Goose Pagoda straightened and reset
Figure 14 Ground fissure and subsidence information management system in Xi'an
5) An early warning information management system for ground fissure and ground subsidence disasters in Xi’an was established (Figure 14). It provides information services and decision-making basis for Xi'an's urban construction planning and ground fissure disaster prevention and control, and also provides a technical demonstration for ground fissure disaster early warning information management in other cities in my country.
This result not only covers the latest theories and methods in the field of ground fissure and land subsidence research at home and abroad, but also combines new problems that arise in major engineering practices and absorbs recent advances in modern geology, engineering geology, New methods and technologies in the fields of geotechnical engineering, geophysics, and remote sensing mapping science have proposed a series of new theories and methods for preventing and controlling ground fissures and land subsidence disasters (Figure 15).
Figure 15 Developed Instruments and Equipment
2. Application Scope and Application Examples
The project results have been widely used in national geological disaster investigation and evaluation, geological disaster monitoring In the construction of early warning projects, urban disaster prevention and reduction, and major engineering projects such as high-speed railways, highways, long-distance pipelines, and urban pipe networks, national ground fissure disaster reduction technology demonstrations have been formed, and my country's ground fissure research has been advanced to the international forefront.
1. Application in national geological disaster early warning and prevention and control
This result has been applied to ground fissure and ground subsidence in Beijing, Harbin, Hebei, Shanxi, Shaanxi, Shanghai, Suzhou, Wuxi and Changzhou, etc. In the investigation, detection, monitoring and prevention work, it has effectively guided the monitoring and prevention of ground fissures and ground subsidence in these areas, and improved the technical level of the industry.
2. Application in urban subway construction
This result has been applied in the design and construction of Xi'an Metro Lines 1 to 3, providing guidance for the safe operation of Metro Line 2. Technical support, and will continue to provide important technical support for the construction of the remaining 12 subways in Xi'an.
3. Application in high-speed railway and highway construction
The results have been used in the survey and design of many expressways in Shaanxi and Xi'an, the Daxi Passenger Dedicated Line and other high-speed railways, providing The route selection and design of the expressway and railway provided important technical support and ensured the safe operation of the highway project through the ground fissure zone.
4. Application in large-scale water diversion projects
This result has been applied in the survey, design and construction of the Heihe Water Diversion Project in Xi'an City, solving the problem of ground fissure disaster reduction technology in the water pipeline network difficult problems, providing technical support for Xi’an’s water safety.
5. Application in long-distance pipeline engineering
The results have been applied by Changqing Science and Technology Engineering Co., Ltd. (Design Institute) to the Jingxian Oil Pipeline and the West-East Gas Pipeline, etc. During the survey and design of the project, the problem of reducing the risk of ground fissures in oil (gas) pipelines was successfully solved.
6. Application in urban construction
This result has been promoted and applied to ground fissure disaster prevention and reduction in many cities such as Xi'an, Beijing, and Datong, saving construction land and mitigation projects The potential economic benefits generated by disaster losses are huge, and it has been identified as an international urban ground fissure disaster reduction technology demonstration by the International Association of Engineering Geology.
This achievement has been widely used in teaching, scientific research and production practice in China, and has significant social and economic benefits. This achievement successfully solved a series of major technical problems in preventing and controlling ground fissure disasters in Xi'an subway tunnels. It was applied to Xi'an's Heihe water diversion pipeline project to save 150 million yuan of investment, and was applied to the Changqing Oilfield infrastructure construction to save 180 million yuan of investment. Since ground fissures and ground subsidence disasters are serious in my country, this achievement will continue to play an important role in the prevention, control and monitoring of ground fissures and ground subsidence disasters in my country, and has very broad application prospects.
3. Promotion and transformation methods
1) The results have been presented at the 3rd National Geotechnical and Engineering Academic Conference, the 2009-2011 National Engineering Geology Conference, and the 3rd National Ground Engineering Geology Conference. Exchanges were held at academic seminars on subsidence prevention and control as well as prevention of Geo-Hazards in Western China and The Fifth International Symposium on Mitigation of Geo hazards in Area around Japan Sea (Figure 16), and were widely recognized by domestic and foreign peers.
Figure 16 Domestic and foreign academic exchanges
2) The project has trained 67 doctors and masters, and trained more than 350 geological disaster monitoring and prevention technicians, forming a nationwide talent training for ground fissure prevention and control. main base.
3) The project has won 1 second prize of the National Science and Technology Progress Award, 3 first prizes of provincial and ministerial science and technology awards, and published 247 papers in core journals, including 41 papers included in SCI and 102 papers included in EI. Articles, 3 academic monographs published, 8 national patents, and 3 software copyrights were obtained. It has had a significant academic impact at home and abroad, and has promoted my country's ground fissure research to the international forefront.
Technical support unit: Chang'an University
Contact person: Yang Hongbin
Correspondence address: Science and Technology Department, Chang'an University, middle section of South Second Ring Road, Xi'an
Postal code: 710054
Contact number: 029-82334276
E-mail: yhb1997@chd.edu.cn