Ground fissure geological disasters have brought serious harm to engineering construction, social economy and sustainable development in China and other countries in the world, and its disaster prevention and mitigation is a worldwide problem. With the support of the National Natural Science Foundation, Ministry of Land and Resources, China Geological Survey and local governments, Chang 'an University has undertaken more than ten scientific research projects, such as the key project of the National Natural Science Foundation "Formation Mechanism of Ground Fissures and Continental Dynamics in Wei Fen Basin". The land and resources survey project "Study on monitoring and prevention of ground fissures in Wei Fen" and the Xi subway science and technology project "Study on the harm of Xi ground fissures to subway engineering and prevention measures". Taking urban ground fissures as the research object, these projects, combined with major projects such as large-scale urban rail transit and high-speed railway in China, have carried out systematic and in-depth research on major key scientific and technological problems that may be caused by ground fissures, and achieved a number of original research results in the comprehensive prevention and control technology of ground fissures:
1) puts forward the technical methods to prevent the ground fissure disaster of buildings (structures). The safe avoidance distance (table 1), fortification width and safe thickness of overlying soil layer of buildings with different foundation forms in ground fissure site are put forward. All the achievements have entered the industry regulations, which have avoided a large number of engineering construction disasters and saved a lot of construction land, and provided a demonstration for the disaster reduction of ground fissures in international cities.
Table 1 Minimum Avoidance Distance of Buildings in Ground Fissure Site Unit: m
2) Put forward the key technology of subway engineering to adapt to the large deformation of ground fissures, and successfully solve the technical problem of ground fissures prevention in the construction of urban rail transit in China. Aiming at the hazards of ground fissures to subway tunnels, four tunnel structural forms (Figure 1 ~ Figure 3) and structural fortification parameters adapted to ground fissures are innovatively proposed, including structural sectional deformation joints, flexible joint connection, local enlarged section and closed waterproof structure. The applicability and safety of the proposed structural measures are verified by large-scale physical model tests and numerical simulations (Figures 4 and 5) under various working conditions, and have been applied to the design and safety of Xi 'an subway project.
Figure 1 Structural Measures for Slotting Tunnel Section
Fig. 2 Schematic diagram of waterproof structure
1- structure; 2- rubber plate; 3- polystyrene rigid foam; 4-rivets ensure the reliable fixation of rubber and lining;
5-2 ~ 3mmu steel plate; 6- high density PE board; 7 Ω type water stop and its supporting devices; 8— Pre-set grouting holes
Fig. 3 Large-scale model test of segmented slotted tunnel
Figure 4 Large-scale physical model test
Fig. 5 Finite element numerical simulation under different working conditions
3) The prevention technology of ground cracks in high-speed railway, expressway and underground pipeline engineering is put forward. Through large-scale physical model test and numerical simulation analysis (Figure 6 to Figure 9), it is found that the failure modes of subgrade are bending, torsion and shear failure; The failure modes of the bridge are falling beam, dislocation and rigid torsion-shear failure modes; The failure modes of underground pipelines include cantilever beam failure mode with upturned end and elastic foundation beam failure mode with reverse bending. The anti-crack design scheme of roads, bridges and underground pipelines is put forward.
Fig. 6 subgrade deformation caused by ground fissures and its treatment measures
Fig. 7 Simulation of Bridge Deformation Caused by Ground Fissures
Fig. 8 Ground fissure and pipeline model test
Figure 9 Xi 'an Underground Pipe Network and Ground Fissure Intersection Plan.
4) The comprehensive disaster reduction technology of urban ground fissures has been formed. Among them, the optimized groundwater exploitation scheme has effectively slowed down the activities of ground fissures in inland basins in loess areas of China, and realized the rational development and utilization of groundwater based on ground fissure prevention (Figure 10 ~ Figure 13).
Figure 10 Xi 'an Ground Fissure Disaster Control Model
Figure 1 1 Xi 'an Three-dimensional Seepage Simulation of Water-soil Coupling
Fig. 12 curve of ground fissure activity rate slowing down after implementing groundwater exploitation restriction scheme.
Figure 13 Groundwater recharge resets the tilted Big Wild Goose Pagoda.
Figure 14 Xi area ground fissures and land subsidence information management system
5) An early warning information management system for ground subsidence disaster of ground fissures in Xi 'an is established (Figure 14). It provides information service and decision-making basis for urban construction planning and ground fissure disaster prevention in Xi, and also provides technical demonstration for ground fissure disaster early warning information management in other cities in China.
This achievement not only covers the latest theories and methods in the research field of ground fissures and land subsidence at home and abroad, but also absorbs the new methods and technologies in the fields of modern geology, engineering geology, geotechnical engineering, geophysics and remote sensing mapping science in recent years, and puts forward a series of new theories and methods for the prevention and control of ground fissures and land subsidence disasters (Figure 15).
Figure 15 Instrument and Equipment Development
Second, the scope of application and application examples
The results of the project have been widely used in national geological disaster investigation and evaluation, geological disaster monitoring and early warning projects, urban disaster prevention and mitigation, high-speed railways, expressways, long-distance pipelines, urban pipe networks and other major projects, forming a national demonstration of ground fissure mitigation technology, pushing China's ground fissure research to the international frontier level.
Application of 1. in national geological disaster early warning and prevention
This achievement has been applied to the investigation, detection, monitoring and prevention of ground fissure land subsidence in Beijing, Harbin, Hebei, Shanxi, Shaanxi, Shanghai, Suzhou, Wuxi and Changzhou, which effectively guides the monitoring and prevention of ground fissure land subsidence in these areas and improves the technical level of the industry.
2. Application in urban subway construction.
This achievement has been applied to the design and construction of Xi subway 1 ~ 3 line, providing technical support for the safe operation of Metro Line 2, and will continue to provide important technical support for the construction of Xi rest 12 subway.
3. Application in high-speed railway and highway construction.
This achievement has been applied to the survey and design of several expressways, Daxi Passenger Dedicated Line and other high-speed railways in Shaanxi and xi 'an, which provides important technical support for the route selection design of these expressways and railways and ensures the safe operation of highway projects crossing ground fissures.
4. Application in large-scale water diversion project
This achievement has been applied to the investigation, design and construction of Heihe River diversion project in Xi 'an, which solves the technical problem of ground fissure disaster reduction in water distribution network and provides technical guarantee for water safety in Xi 'an.
5. Application in long-distance pipeline engineering
This achievement has been applied by Changqing Science and Technology Engineering Co., Ltd. (design institute) in the survey and design of Jingxian oil pipeline and West-East gas pipeline, and successfully solved the problem of ground fissure disaster reduction of oil (gas) pipeline.
6. Application in urban construction
This achievement has been applied to the prevention and mitigation of ground fissures in Xi 'an, Beijing, Dalian and other cities, saving construction land and reducing the loss of engineering disasters, resulting in a huge potential economic benefits, which has been identified by the International Association of Engineering Geology as a technical demonstration of ground fissures mitigation in international cities.
At present, this achievement has been widely used in China's teaching, scientific research and production practice, with remarkable social and economic benefits. This achievement has successfully solved a series of major technical problems in the prevention and control of ground fissures in Xi 'an subway tunnel, and saved investment of 654.38+0.5 billion yuan when applied to Xi 'an Heihe water diversion pipeline project, and 654.38+0.8 billion yuan when applied to infrastructure construction in Changqing Oilfield. Due to the serious disasters of ground fissures and land subsidence in China, this achievement will continue to play an important role in the prevention and monitoring of ground fissures and land subsidence in China, and it has a very broad application prospect.
Third, promote the transformation mode.
1) This achievement has been exchanged at the 3rd National Academic Conference on Geotechnical Engineering, the National Engineering Geology Conference from 2009 to 20/1,the 3rd National Symposium on Land Subsidence Prevention and Geological Disaster Prevention in Western China, and the 5th International Symposium on Geological Disaster Mitigation around Japan's Sea Area (Figure 16), and it has been shared by colleagues at home and abroad.
Figure 16 Academic Exchange at Home and Abroad
2) The project has trained 67 doctors and masters, trained more than 350 technicians for monitoring and preventing geological disasters, and formed the main base for training ground fissure prevention talents in China.
3) The project won the second prize of national science and technology progress 1 item, 3 first prizes of provincial and ministerial level science and technology, and published 247 core journal papers, including 4 papers in SCI, 2 papers in EI, 3 academic monographs, 8 national patents and 3 software copyrights, which had a great academic impact at home and abroad.
Technical support unit: Chang 'an University
Contact: Yang Hongbin
Mailing address: Science and Technology Department of Chang 'an University in the middle section of the Second Ring Road in the south of Xi 'an.
Postal code: 7 10054
Tel: 029-82334276
Email: YHB 1997@chd.edu.cn