Records of Compaction Subsidence of Argillaceous Sediments in the Modern Yellow River Delta

Abstract

The distributary lobe of the modern Yellow River Delta formed after 1855 was 15 m in thickness before it was abandoned, where the compaction subsidence has reached as high as 2.28∼3.87 m in the past 30 years. The compaction ratio of clayey silty sand (25.8%) is 1.7 times greater than that of silty sand (15.2%). It means that the compaction process has basically terminated. On the other hand, the compaction subsidence of underlying sediment is quite limited and shows an insignificant difference. For example, for the underlying sediment of 20∼30 m in thickness, the subsidence varies between 0.2 and 0.28 m. The average compaction ratio of clayey silty sand is 0.91%, while that of silty sand is 1.19%, and the average compaction ratio of all sediment is 1%. There's a negative exponential function relationship between porosity and burial depth of the sediment, and the higher the clay content, the more difficult it is for pore water to drain. The superficial sediments contribute more to the compaction subsidence than the underlying strata.