Study On Dynamic Characteristic And Model Of Seismic Observation Hole In Dahuichang Quarry In Beijing

The observation hole in the fault can effectively reflect the changes in the structure of the Earth, is an important way to the observation of earthquake fluid. However, the groundwater level is not only induced by crustal stress, but rainfall, air pressure and other factors. To identify and remove the factors in the fluid of the earthquake is important and difficult.Combined with specific hydrogeology of study area, this paper is based on constructing a tank model on fault, simulating fault dynamic characteristics of groundwater level of observation wells, to reflect the groundwater response to precipitation.Babaoshan fault is one of the controlling fault in Beijing, until now is still active. Dahuichang observation well is located in the central of Baobaoshan Fault. To understand the meteorological, hydrogeological conditions, groundwater dynamics of study area, is play an important role in the identification of influence factor. In this paper, the analysis of hydrogeology, groundwater, rainfall characteristics of the Dahuichang area is to verify that the rainfall is the main factors of seismic changes in underground water level. Based on the weather data of the area, use tank model to simulate ground water level of the earthquake observation hole.According to the structural feature of faults, the rocks can be divided into unconfined and confined zones. The rock of top wall covers the confined zones. And there exists weathered fracture zone at the top of the upper areas, which receive rainfall recharge. Also this area discharges to the unconfined area of fault zone at a quantitative flow. The fault zone receives recharge from groundwater of weathered zones and rainfall, and discharges water at the base-level somewhere. According to the principle of water balance, the relationship of rainfall infiltration and the groundwater level between the fault zone and weathered areas can be determined. After adjusting parameters, linear model with five parameters gives a simulation result of groundwater that changing trend with actual is uniform. This simulation basically describes the dynamic characteristics of groundwater. However, the groundwater level showed no response to the precipitation between few years. So the water level of simulated is largely difference with the reality. We should make further analysis of other influencing factors.Finally, draw the preliminary conclusions. The water level of Dahuichang observation well is significantly influenced by precipitation. In addition to the impact of precipitation, the role of surface water bodies can not be ignored. What's more, this model can not identify the function of structure factors in dynamics of the groundwater level. So The model needs further improvement.