Classification of soil types for Hanoi (Vietnam) when studying land subsidence at groundwater extraction

Abstract

The relevance of the discussed issue is caused by the necessity to study land subsidence in Hanoi (Vietnam). Hanoi is one of the largest cities in Asia with the developed industry, infrastructure and high population density. The city is located in the area with complicated natural conditions and active earthquake. A characteristic feature of the geological structure in the city is the presence of soft soils with large thickness and intensive manifestation of dangerous natural and man-made geological processes. One of them is land subsidence caused by intensive groundwater exploitation for water supply. Water consumption in Hanoi is increasing annually. The land subsidence is followed by deformations and damages of engineering structures. The main aim of the study is classification of soil types and establishment of map of soil type distribution for prediction of land subsidence in Hanoi caused by the groundwater extraction. The methods used in the study: collecting and analyzing data on geology, hydrology, soil properties. The results. The paper introduces the properties of quaternary deposits, engineering-geological sections, maps of thickness and distribution of soft soils and a map of stratum subdivision for Hanoi territory. The strata are subdivided into 4 classes, 6 types and 9 kinds. The types that mainly predetermine land subsidence after groundwater drawdown are pointed out. The results can be used to predict other engineering-geological processes due to the changes in natural conditions and human activities in Hanoi.

Keywords

• land subsidence
• soft soils
• strata subdivision
• Hanoi