CENTRIFUGAL SIMULATION EXPERIMENT FOR A LOESS CUTTING-SLOPE AT YANGYA, YAN'AN CITY, NW CHINA

Artificial excavation is one of the main inducing factors of the landslide formation in loess area. It causes unloading rebound and stress redistribution within the scope of slopes. The process of slope stress rebalancing is followed by slope deformation, which even causes damage. The landslide happened at Baota Zaoyuan town in Yan'an city is a typical induced loess slope excavation. This paper chooses the Yangya landslide as the geological prototype. It uses the type of TLJ-500geotechnical centrifuge for the condition of excavation slope foot test to simulate the deformation and failure process. It studies the characteristics of the displacement of slope deformation before and after the excavation of the slope foot, slope soil pressure response and mechanism of slope deformation and destruction through analysis of the model monitoring data at monitoring points. Results show that partial collapse happens after the slope toe excavation near the international airport face. The slope displacement, shear stress concentration belt and tensile fracture increase progressively from the front part to the inner part of the slope. After excavation, the slope internal zone can produce obvious stress relaxation. The closer to the excavation face the more obvious effect of unloading. Excavation influences a majority of the front and middle parts of the main slope. So there is less or even no effect at the back slope, which means that slope deformation failure mechanism is the typical-steps-back type.