Influence Of Groundwater Development Law On Land Subsidence In Panyu

Under the background of promoting the development of the Guangdong,Hong Kong,and Macao Greater Bay Area and the “The Belt and Road”,Panyu will usher in more development opportunities.Panyu will expand its scale of construction.The number of engineering construction projects will increase.In the process of urban construction,groundwater is a disaster factor for many geological disasters.In addition,the hydrogeological information of Panyu District is very old.Therefore,the investigation of groundwater development law in Panyu District and the analysis of the impact of changes in groundwater level on land subsidence disasters are of significance to the planning and construction of Panyu and it is also an urgent need for the prevention and control of urban geological disasters.In this paper,during the investigation of groundwater development law in Panyu District,meteorological and hydrological data,DEM data,and geological reports of Panyu District were collected and tests such as water sample collection,hydrogeological tests,and gas detection were conducted.After investigation and analysis,groundwater types in Panyu District can be classified into loose rock pore water and bedrock fracture pore water.Except that the groundwater in the deep part of the alluvial plain is salt water,the remaining groundwater is fresh water.Except for part of the Quaternary sand layer adjacent to the Pearl River,the water yield property is moderate,and the water yield property of the remaining groundwater aquifers are poor.The source of groundwater recharge in the platform area is atmospheric precipitation,which is drained by the descending spring and supplies the alluvial plain aquifer laterally.The sources of shallow groundwater recharge in alluvial plains are mainly atmospheric precipitation,which is mainly excreted by transpiration.The groundwater in the deep part of the alluvial plain belongs to sealed-type groundwater,with no external recharge,and the runoff is weak.The excretion route is artificial bolting.The corrosive rating of groundwater for concrete structures in Panyu is slightly weak.In the long-term immersed groundwater environment,the corrosiveness of the groundwater to the reinforced concrete in the reinforced concrete is in the order of micro-weakness,and in the dry-wet alternating environment,the corrosiveness grade is in the micro-to-moderate range.Based on the investigation of the development law of groundwater in Panyu District,Hualong Town and Shilou Town in Panyu are selected as the research objects,and the effects of different types of groundwater level changes on land subsidence are analyzed.After analysis,groundwater changes caused by engineering precipitation will aggravate the ground settlement in the study area.The change of groundwater level caused by rainfall and tide has no obvious effect on the land subsidence and development of the study area.In view of the land subsidence caused by the engineering precipitation,the land subsidence value of the research field under different depth reduction conditions was calculated and analyzed.It is found that in the engineering precipitation,the controlling factor of land subsidence is the thickness of soft soil.The study area is divided by the thickness of soft soil and the land subsidence under different depths is calculated for each area.According to calculations,when the depth of the water depth drops to 6.5m in the soft soil thickness range of 10 to 15 m,the amount of ground subsidence reaches the critical value.When the water depth drops to 4m in the soft soil thickness area of 15~20m,the land subsidence amount reaches the critical value.In areas where the thickness of soft soil is more than 20 m,when the water depth drops to 3m,the amount of ground subsidence reaches the critical value.According to the calculation results,the area with soft soil thickness of 0-10 m is the low-prone area of land subsidence caused by engineering precipitation.The soft soil thickness of 10~20m is the medium-prone area where geological disasters are caused by precipitation,and the critical depth of water level drop is 4m.The area with a soft soil thickness of 20 m or more is a high-prone area where geological disasters are caused by precipitation.The critical value for water depth drop is 3m.