Research and Engineering Application of Soft Soil Unloading and Deformation Model

Abstract

Soft soil is a multiphase medium composed of solid soil particles, pore water, pore gas and combined water film adsorbed on the surface of particle group and colloid between particles. It is widely distributed in coastal, middle and lower reaches of rivers and delta of lakes. Its physical and mechanical properties and engineering characteristics are complex and regional differences are obvious. With the rapid development of social economy and urbanization, it will inevitably lead to serious problems such as urban land tension, traffic congestion and environmental pollution. These coastal cities are the leaders of China’s economic development. After more than 30 years of rapid economic development, the construction scale of these cities in China is also expanding, and the supply and demand of construction land is becoming increasingly tight. The contradiction between supply and demand is more prominent. With the scarcity of land resources and the rapid development of economy, a large number of construction projects in Qianhai area have been started, among which the construction of subway is also on a large scale. The shortage of land resources and the increase of land development make the high density and high strength building development along the subway line. The development of these building properties is bound to appear a large number of complex deep foundation pit projects, and the excavation of deep and complex foundation pit near the side of subway tunnel is a common form of excavation. In practical construction projects, due to the influence of external factors such as complex construction site conditions and urgent time requirements, people often pursue the progress of foundation pit excavation too much in actual construction, ignoring the research and application of mechanical properties of soft soil foundation, which leads to the safety accidents of subway tunnel structure from time to time. This is closely related to the mechanical properties of soft soil with high moisture content, high compressibility and low bearing capacity. Therefore, deep and large foundation pit engineering in soft soil area is prone to heavy engineering safety problems such as underground continuous wall and other retaining structures. Therefore, the further study of the unloading deformation model of soft soil, the physical and mechanical properties and engineering characteristics of soft soil has a positive and important economic value and social role in engineering in the future.