With the support and funding of the National Natural Science Foundation, the Ministry of Land and Resources, the China Geological Survey and the local government, the research group on ground fissures and land subsidence of Chang 'an University has formed a set of achievements including the contents, methods and technical requirements of ground fissures investigation, monitoring contents, monitoring methods and technical requirements, ground fissures evaluation contents, evaluation methods and index system.
1. formed a set of systematic ground fissure investigation methods.
According to the characteristics of different types of ground fissures, different investigation contents and working methods are put forward, as well as the accuracy requirements of ground fissures investigation at different scales.
2. A complete set of ground fissure site investigation method has been formed.
1) According to the exposure of ground fissures and different exploration marker layers, the types of ground fissure sites (Ⅰ, Ⅱ and Ⅲ) are divided, and the specific exploration means and technical requirements of different ground fissure sites are put forward.
2) Fine detection and high-precision interpretation technology of ground fissures have been developed. The collected data are detected by multiple coverage reflection method, and the information of first break reflection wave is picked up. The shallow velocity field is retrieved by using ct imaging technology (Figure 1). The developed CT imaging information processing technology can effectively identify shallow ground fissures and solve the technical problem of locating and detecting 50m shallow ground fissures.
Figure 1 CT imaging can effectively identify the shallow fracture information interpretation profile.
3. The genetic models and mechanism research methods of different types of ground fissures are put forward.
Including structural crack control (Figure 2 to Figure 3), stress-induced crack (Figure 4) and pumping crack propagation (Figure 5 to Figure 7).
4. The methods, contents and technical standards of ground fissure monitoring are put forward, and high-precision GPS monitoring, InSAR monitoring and their fusion monitoring technologies and monitoring equipment are developed.
The fine processing method of GPS monitoring data (Figure 8) realizes the monitoring ability of ground subsidence and ground fissure deformation characteristics with vertical accuracy higher than 3 mm; Carry out InSAR technology, small baseline (SBAS) technology, artificial corner reflector (CR) technology, InSAR processing for new satellites and multi-satellite platforms, and post-processing methods for monitoring ground fissures in different regions to achieve the monitoring accuracy of "millimeter" order; Based on the fusion technology of GPS and CR-InSAR, and the InSAR error correction model and method of CR-GPS fusion, the high-precision monitoring of ground fissures in the order of 1 ~ 2mm is realized. Three-dimensional real-time dynamic monitoring instruments for ground fissures are developed, including artificial corner reflector based on GPS movement and three-dimensional deformation measuring instrument for ground fissures (Figure 9).
Fig. 2 model of deep structural pregnancy and fracture in Xi' an area
Fig. 3 Ground fissure model of Lintong Chang 'an fault.
Fig. 4 Relationship between ground fissures and regional tectonic stress in Weihe Basin
5. The evaluation index system of ground fissures is established, and the comprehensive classification scheme and comprehensive evaluation method of ground fissures are put forward.
The evaluation content of ground fissures includes the cause determination, activity evaluation, trend prediction, disaster mechanism analysis and risk evaluation. The evaluation indexes include sedimentary facies and thickness of loose strata, aquifer distribution, stratum structure, topography, physical and mechanical properties of rock and soil, historical disaster degree of ground fissures, buried depth of groundwater level, groundwater exploitation intensity and other human engineering activities. Evaluation methods include genetic algorithm, artificial neural network, grey cluster analysis, fuzzy comprehensive evaluation, analytic hierarchy process, geographic information system and so on. Ground fissures are divided into giant, extra-large, large, medium and small according to their scale; According to mechanical properties, it can be divided into shear type, tensile type, tension-shear type and compression-shear type; According to the openness, it can be divided into closed type, split type, open type, wide type, extremely wide type and extremely wide type; According to the degree of activity, it is divided into strong activity, strong activity, medium activity and weak activity; According to the primary and secondary relationship, it is divided into main cracks, branch cracks and secondary cracks; According to the formation reasons, it can be divided into structural type (fault creep and earthquake cracks) and non-structural type (collapse, subsidence, expansion and contraction and landslide cracks, etc.). ) and composite (settlement and structural coupling).
Fig. 5 Relationship between ground fissure and ground subsidence center
Fig. 6 differential settlement compression crack propagation mode of clay layer
Fig. 7 Horizontal displacement crack propagation mode of aquifer
Fig. 8 high-precision HPGPSADJ software and GPS post-processing software
Fig. 9 3D deformation measuring instrument for ground fissures
Second, the scope of application and application examples
The technical methods of ground fissure investigation and monitoring can be applied to the investigation and design of geological disasters, urban construction planning, industrial and civil buildings, highways, railways, lifelines and other different stages. This technical method has been successfully applied to the investigation and monitoring of ground fissures in Wei Fen Basin, North China Plain, Northeast China and East China (figure 10, figure1), Xi 'an subway (figure 12), Da 'an high-speed railway (figure 13) and Beijing Future Science and Technology.
Figure 10 monitoring of ground fissures in Xi area of Weihe basin
Figure 1 1 monitoring map of ground fissures in Qingxu, Taiyuan Basin
Figure 12 Xi Risk Assessment of Ground Fissures along Metro Line 4
Figure 13 Investigation Results of Ground Fissures along Da 'an-Xi 'an High-speed Railway
Figure 14 Investigation and Evaluation Results of Ground Fissure Site of State Grid Smart Grid Research Institute of Beijing Future Science and Technology City
Third, promote the transformation mode.
This achievement won 3 first prizes of provincial and ministerial level science and technology, published 247 core journal papers, including 4 SCI papers1paper, 2 EI papers 102, published 3 academic monographs, obtained 8 national patents and 3 software copyrights, which had a great academic impact at home and abroad. At the third national academic conference on geotechnical engineering, the national conference on engineering geology from 2009 to 20 12, the third national symposium on land subsidence prevention and geological disaster prevention in western China, and the fifth international symposium on geological disaster reduction in East Asia, it has been widely recognized by colleagues at home and abroad, especially by Professor Carlos Delgado, president of the International Association of Engineering Geology and Environment (IAEG).
This achievement can be further popularized and applied through publicity and reporting, conference exchange, personnel training, technical consultation and on-site service.
Technical support unit: Chang 'an University
Contacts: Yang Hongbin, Lu Quanzhong
Mailing address: Science and Technology Department of Chang 'an University in the middle section of South Second Ring Road, Xi 'an, Shaanxi Province.
Postal code: 7 10064
Tel: 029-82334276,18049518981.
E-mail: DCDGX 14@chd.edu.cn YHB 1997@chd.edu.cn