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江阴南部地区在构造上呈现“两隆一凹”的格局,南、北边缘为基岩隆起带,中心为第四系松散沉积平原,受基底起伏及古河道的控制,土层厚度、岩性、结构及水文地质特征差异较大。由于长期超量开采第Ⅱ承压水,不仅形成了区域水位降落漏斗,也形成了地面沉降漏斗,最大水位漏斗中心水位埋深约75m,沉降漏斗中心最大沉降量达1 300mm以上。并在长泾、河塘、祝塘等地由于差异沉降形成三处地裂缝,这些裂缝具有相似的发育特征,即在主裂缝处形成陡坎,陡坎高约10~30cm,主裂缝的NW侧则相对下错并形成宽约20~60m的凹陷带,带中发育有规模较小的次级裂缝。基底隆起及其所控制的第四系松散层厚度及结构差异是地裂缝发育的空间乃至时间特征的基础,是控制因素;深层地下水的长期超量开采所导致的地层压缩或固结是地裂缝形成的主导因素,地裂缝正是基岩隆起带地层差异压缩所形成的差异地面沉降的结果。据估算,其发育深度可达基岩隆起的最浅处,并实际上已发展成为小断层。
The southern part of Jiangyin is structurally characterized by a pattern of “two lumps and one depression”. The south and north edges are bedrock uplifts and the center is Quaternary unconsolidated sedimentary plain. It is controlled by the basement undulation and the ancient channel, the thickness of the soil layer, the rock Sexual, structural and hydrogeological features vary widely. Due to the long-term overexploitation of No.2 confined water, not only the regional water level dropping funnel but also the ground subsidence funnel was formed. The water level at the center of the maximum water level funnel was about 75m, and the maximum settlement at the center of the settling funnel reached 1,300mm. In Changjing, Hetang and Zhutang, there are three ground fissures due to differential subsidence. These fissures have similar developmental features, ie, a steep ridge is formed at the main crack with a height of about 10-30 cm. The NW of the main crack The side is relatively under the wrong and the formation of about 20 ~ 60m wide depression zone, the development of a smaller secondary cracks in the belt. The basement uplift and the controlled thickness and structure of the Quaternary loose layer are the basis for the spatial and even temporal characteristics of ground fissure development and are the controlling factors. The formation compression or consolidation caused by the long-term over-exploitation of deep groundwater is the result of ground fissure The leading factor of formation is that the ground fissure is the result of the differential land subsidence formed by the differential compression of bedrock uplift belt. It has been estimated that its depth of development reaches the shallowest point of bedrock uplift and has actually evolved into a small fault.