关键词: 古河道, 地面沉降, 地下水, 工程地质条件, 水文地质条件

Abstract: The influential factors of ground surface subsidence in Donggugang, Hebei Plain, are examined systematically through engineering geological, hydrogeological and environmental geological explorations via technical approaches such as geophysical prospecting, drilling, and leveling, together with follow-up surveys on the status and harm of land subsidence. The results are concluded as follows: (1) Located in the Quaternary change belt of ancient stream channels, the study area is of weak compressive strength and large collapsibility with loose materials. The ancient stream channel and flood plain are prone to dislocated ruptures due to the effects of the saturated dead weight of sand layer, the infiltration of groundwater, and the difference of pore water pressure. (2) The external factor, and also, the driving force, of ground subsidence in the study area is the decline of shallow groundwater level; sedimentary difference is the internal factor which provides the material basis for uneven settlement; secondary factors include deep groundwater changes, geological tectonic activity, and artificial backfilling ponds, pools and etc. The research findings would offer theoretical basis for the study and prevention of ground subsidence in the Hebei plain.

Key words: ancient stream channel, ground surface subsidence, groundwater, engineering geological condition, hydrogeological condition