生物洞穴影响的黄河口粉质土优势流及其效应研究

Study on preferential flow and effect on silt by simulative burrows in Yellow River Estuary

生物扰动对沉积物性质的改变已越来越受国际地圈生物圈计划的关心。通过高密度电阻率法和示踪剂相结合的方法,监测了室内模拟黄河口生物洞穴影响非饱和粉土的渗流。从入渗的电剖面特征分析,发现渗流主要发生在生物洞穴形成的大孔隙通道中,而周围基质中的渗流很弱,即黄河口粉土的生物洞穴中存在优势流。优势流在细粒土的垂直迁移中有重要作用,同时也改变了大孔隙周围土体的基本性质,如密度、含水量、强度、颗粒组成以及电导率等。优势通道在入渗过程中可增加周围土体的含水量,但在排水的过程中也可增加周围土体的排水能力,具有增水和排水的双重效应。

The properties of sediments changed by bio-disturb have been concerned by International Geo-sphere and Biosphere Plan （IGBP）. The high density resistivity integrates with a tracer to measure the process of infiltration on the silt in the Yellow River Estuary with the simulative burrows in the laboratory. Based on the analysis of the profile and section characteristics of apparent resistivity, it is found that the infiltration mainly is in the large pore channel produced by burrows and is weak in the surrounding matrix. That is the preferential flow exists in the silt in the Yellow River Estuary with burrows. The preferential flow plays an important role in the vertical transportation of the fine grain. Meanwhile, it also changes the basic properties of the soil around the burrows, such as density, water content, strength, grain size and electrical conductivity, etc. The channel of the preferential flow not only can increase the water content of the surrounding matrix during the process of infiltration, but also can increase the drainage capacity of surrounding matrix during the process of drainage. It means that the burrows have the dual effects of increase water and decrease water for the surrounding matrix.