1. Overview of contents
With the support and funding of the National Natural Science Foundation of China, the Ministry of Land and Resources, the China Geological Survey and local governments, the research group of ground fissures and ground subsidence in Chang 'an University has formed a set of results including ground fissures investigation contents, investigation methods and technical requirements, ground fissures monitoring contents, monitoring methods and technical requirements, ground fissures evaluation contents, evaluation methods and index system.
1. A set of systematic ground fissure investigation methods has been formed.
According to the ground fissures with different genetic types and characteristics, different investigation contents and working methods, as well as the accuracy requirements of ground fissure investigation with different scales are put forward.
2. A complete set of ground fissure site investigation methods has been formed
1) According to the exposure of ground fissures and different exploration marker layers, the ground fissure site types (Class I, Class II and Class 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. Using multiple coverage reflection method to detect the collected data, picking up the information of first break reflection wave, and using CT imaging technology, the velocity field of shallow stratum is inversed (Figure 1). The developed CT imaging information processing technology can effectively identify shallow ground fissures and solve the technical problem of locating and detecting shallow ground fissures at 5m.
fig. 1 CT imaging can effectively identify the information interpretation profile of shallow fractures
3. The research methods of genetic models and mechanisms of different types of ground fissures are put forward
The coupled genetic theory of ground fissures includes structural control fissures (figs. 2 to 3), stress guiding fissures (fig. 4) and pumping expansion fissures (figs. 5 to 7).
4. The methods, contents and technical standards of ground fissures monitoring are put forward, and the high-precision GPS monitoring, InSAR monitoring and their fusion monitoring technologies and the precise processing method of GPS monitoring data studied by monitoring equipment
(Figure 8) are developed, which realizes the ability of monitoring the deformation characteristics of ground fissures with vertical accuracy higher than 3 mm; InSAR technology, small baseline (SBAS) technology, artificial corner reflector (CR) technology, InSAR processing of new satellites and multi-satellite platforms, and In-SAR monitoring post-processing method are carried out to monitor ground fissures in different regions, achieving the monitoring accuracy of "millimeter" order; The fusion technology of GPS and CR-InSAR based on the mobile artificial corner reflector at the GPS monitoring point and the correction model and method of InSAR error through the fusion of CR and GPS have realized the high-precision monitoring of ground fissures in the order of 1 ~ 2 mm. 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 shows the model of deep structural fracture in Xi' an
fig. 3 shows the model of ground fissures derived from Chang' an fault in Lintong
fig. 4 shows the relationship between ground fissures and regional tectonic stress in Weihe basin
5. The index system of ground fissures evaluation is established, and the comprehensive classification scheme and comprehensive evaluation method of ground fissures are put forward.
The evaluation content of ground fissures includes ground fissure genesis determination, activity evaluation, trend prediction, disaster-causing 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, etc. Evaluation methods include genetic algorithm (GA), artificial neural network (ANN), grey clustering analysis, fuzzy comprehensive evaluation, analytic hierarchy process, geographic information system (GIS) 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, tension type, tension-shear type and compression-shear type; According to the degree of opening, it can be divided into closed, split, open, wide, very wide and extremely wide types; According to the degree of activity, it is divided into strong activity, strong activity, medium activity and weak activity; Divided into main cracks, branch cracks and secondary cracks according to the primary and secondary relationship; According to the formation reasons, it can be divided into structural type (fault creep and earthquake cracks), non-structural type (collapse, subsidence, expansion and contraction and landslide cracks, etc.) and composite type (settlement and structural coupling).
fig. 5 relationship between ground fissure and ground subsidence center
fig. 6 differential settlement compression crack expansion mode of clay layer
fig. 7 horizontal displacement crack expansion mode of aquifer
fig. 8 high-precision HPGPSADJ software and GPS post-processing software
fig. 9 ground fissure three-dimensional deformation measuring instrument
II. Application scope and application examples
Ground fissure investigation and monitoring technology and methods can be applied to geological disaster investigation and urban construction planning. This technical method has been successfully applied to the investigation and monitoring of ground fissures in Fenwei Basin, North China Plain, Northeast China and East China (Figures 1 and 11), and has been applied in major projects such as Xi 'an subway (Figure 12), Datong-Xi 'an high-speed railway (Figure 13), Beijing Future Science and Technology City (Figure 14) and urban construction planning in Xi 'an, which has made contributions to disaster reduction and prevention in major cities and major projects, and has been used in more than 2 projects.
figure 1 monitoring of ground fissures in Xi' an area of Weihe basin
figure 11 monitoring of ground fissures in Qingxu area of Taiyuan basin
figure 12 risk assessment of ground fissures along Xi' an metro line 4
figure 13 survey results of ground fissures along Datong-Xi' an high-speed railway
figure 14 survey and evaluation results of ground fissures in State Grid Smart Grid Research Institute of Beijing Future Science and Technology City
III, Promotion and transformation mode
This achievement has won 3 first prizes of provincial and ministerial level science and technology, published 247 core journal papers, including 41 papers included in SCI and 12 papers included in EI, published 3 academic monographs, won 8 national patents and 3 software copyrights, which has had a significant academic impact at home and abroad; At the Third National Academic Conference on Geotechnical and Engineering, the National Engineering Geology Conference from 29 to 212, The 3rd National Symposium on Land Subsidence Prevention and Control and "Prevention of Geo-hazards in Western China and the Fifth International Symptom on Mitigation of Geo-hazards in area around Japan S" Ea "and other international academic conferences, which were widely recognized by domestic and foreign peers, especially Professor Carlos Delgado, President of the International Association of Engineering Geology and Environment (IAEG), spoke highly of this achievement.
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
Contact: Yang Hongbin Lu Quanzhong
Address: Science and Technology Department of Chang 'an University, middle section of South Second Ring Road, Xi 'an City, Shaanxi Province
Postal code: 7164
Tel: 29-8234276, 1849518981
Email: yhb1997@chd.edu.cn.