Research on the Construction of Ground Subsidence Monitoring System in Bohai Sea Rim Area

I. Content Overview

Ground subsidence is a major environmental and geological problem facing the development and construction of the Bohai Rim area. Ground subsidence causes loss of ground elevation and failure of tidal embankment in coastal areas, which leads to destruction of engineering facilities, intensification of flooding and storm surge disasters, and poses a great threat to the safety of cities in coastal areas and the safety of major engineering and construction zones. According to the needs of the development and construction of the Bohai Rim area, since 1999, Tianjin Geological Survey Center has carried out ground subsidence monitoring research in Tianjin Binhai New Area and Hebei Caofeidian New Area, and summarized a set of relatively mature technical methods for monitoring ground subsidence in coastal economic development areas. At present, the early warning system for ground subsidence has taken shape, and the results have provided an important geological basis for local economic construction.

The ground subsidence early warning system mainly includes monitoring system, simulation forecasting system and real-time release system, in which the reasonableness and perfection of the monitoring system construction is directly related to the effectiveness of the early warning system, which is the fundamental part of the early warning system construction. The main causes of ground subsidence in the Bohai Sea area include regional ground subsidence caused by over-exploitation of groundwater and tectonic subsidence, local ground subsidence caused by large-scale engineering construction, and consolidation subsidence of unconsolidated strata in reclaimed land areas. In addition, oil, natural gas and geothermal exploitation is also one of the causes of ground subsidence that cannot be ignored. Since the causes of ground subsidence in the Bohai Sea area are diverse and the mechanism is complicated, the selection of ground subsidence monitoring technology and methods is carried out in the construction of the ground subsidence monitoring system for different causes and different mechanisms. The monitoring focuses on the combination of deformation monitoring and groundwater dynamic field monitoring, regional monitoring and key area monitoring, traditional method monitoring and new technology and new method monitoring, and the application of some methods is groundbreaking, such as the construction of a group of stratification markers capable of monitoring the deformation of strata within the depth of 1200m in Binhai New Area, Tianjin, which will be able to provide the direct basis of whether geothermal exploitation produces ground subsidence; Hebei Caofeidian New Area is a project construction area under construction formed by land reclamation, the ground surface is under complex engineering and construction conditions, conventional methods can not be realized ground settlement monitoring, the work of the exploratory application of high-resolution INSAR technology on its ground settlement monitoring research, to obtain a good monitoring effect, a breakthrough in the traditional methods of ground settlement monitoring bottleneck.

The general idea of the ground subsidence monitoring system construction: "combining point and surface, regional control, highlighting the key points". Priority is given to the construction of regional monitoring system, in the construction of regional monitoring system, the spatial integrity characteristics of INSAR monitoring, identify the regional distribution characteristics of ground settlement, and make full use of the advantages of high precision of the regional second-class level measurement to identify the rate of ground settlement, the integration of the two monitoring techniques and methods, to complement each other's strengths and weaknesses, and to improve the accuracy of regional monitoring of ground settlement. When conditions permit, the bedrock marker is established as the measurement base point, and the tectonic subsidence is monitored at the same time; on the basis of regional ground subsidence monitoring, the encrypted leveling network construction is selected for the key areas of ground subsidence, and the layered marker groups are established at key locations for high-precision monitoring of deformation of soil layers at different depths, so as to provide a more accurate data basis for the research on the causes and mechanisms of ground subsidence; the monitoring of ground deformation is carried out in the same time for the monitoring of the groundwater level of aquifers and weakly permeable layers. The monitoring of surface deformation is accompanied by the monitoring of groundwater level in aquifer and weak permeable layer, which provides the basis for the research of ground subsidence mechanism and the establishment of coupled prediction model. According to the above monitoring system construction ideas, the ground subsidence monitoring system has been built in Tianjin Binhai New Area and Hebei Caofeidian New Area respectively, and the monitoring effect is good, and significant social benefits have been achieved.

Scope of application and application examples

1. Scope of application

The idea of Bohai Rim ground settlement monitoring system construction is especially suitable for the coastal economic construction starting area and rapid development area, and it has a reference significance for the research of ground settlement monitoring in other areas.

2. Application examples

The idea is applied in the construction and monitoring of ground settlement monitoring system in Tianjin Binhai New Area and Hebei Caofeidian area. The results of ground subsidence monitoring can clarify the types of causes of ground subsidence in Tianjin Binhai New Area and Caofeidian area, thus providing a direct basis for research on prevention and control countermeasures according to local conditions, and laying a solid foundation for the construction of early warning system of ground subsidence in Tianjin Binhai New Area and Caofeidian area.

Three, the promotion of transformation mode

The results of the promotion of transformation in the form of publicity and reporting, technical consultation and on-site services. At present, the ground settlement monitoring in Tianjin Binhai New Area has been incorporated into the Tianjin ground settlement monitoring system, and realized the monitoring data ****sharing with the Tianjin Settlement Control Office, which plays an important role in the control and management of ground settlement in Tianjin Binhai New Area. The research results of Caofeidian ground settlement monitoring have laid a foundation for the study of ground settlement mechanism in reclaimed land area. In the future, the ground subsidence monitoring system in the Bohai Sea area will provide basic data for the local government to formulate countermeasures for the prevention and control of ground subsidence, and provide technical demonstration for the monitoring and management of ground subsidence in the coastal areas of China.

Technical support unit: Tianjin Geological Survey Center of China Geological Survey

Contact person: Ma Zhen

Correspondence address: No. 4, Dazhigu 8th Road, Hedong District, Tianjin

Postal code: 300170

Contact telephone: 022-84112961

Email: tjmazhen @126.com

Email: tjmazhen