Abstract:

Numerous factors are attributed to the rapid development of subsidence in the plain area of Beijing. The existence of cohesive soils in this area provides the material foundation for subsidence, and therefore, this study focuses on the consolidation characteristics of cohesive soils with depth less than 100 m under different loading condition such as progressive loading, progressive unloading, and repeated loading and unloading in a typical subsidence area in Baxianzhuang within the Changping District of Beijing. According to the test results, the deformation of cohesive soils under progressive loading from 25 kPa to 1,600 kPa is greater than that of silt, which is 2.822 mm and 1.000 mm, respectively. The rebound of cohesive soils under progressive unloading from 400 kPa to 50 kPa is also greater than that of silt, which is 0.277 mm and 0.121 mm, respectively; and under repeated loading and unloading condition, silty clay and silt attain a state of consolidation faster than clay; the creep-time effect is sorted as clay>silty clay>silt. It is therefore recommended that a full consideration should be given to the effects of soil characteristics in subsidence areas when compiling land subsidence disaster prevention and control plans.

Key words: land subsidence, cohesive soil, consolidation test, compression characteristic