Research On Mechanical Mechanism Of Excavation And Unloading Landslide

With the development of the western economy, landslides caused by human engineeringactivities appeared a sharp upward trend, and that triggered by excavation is one of the mostimportant way of the engineering loess landslide. Researching the mechanism of thelandslide is the prerequisite and the important basis that preventing the excavation loesslandslide. The main object is Baqiao landslide in this paper, which of the main mechanicalmechanism that cause the landslide will be analysis on the basis of field investigation,laboratory experiments, numerical analysis. Specific studies as the following results:1）Select the loess of the Baqiao landslide that in the scarp as the sampling point.Through a series of basic physical tests, the soil column absorbent test and conventionaltriaxial compression test and reduced triaxial compression test and conventional triaxialcompression test of loading and unloading, we can find that: The water changes in the thesoil column absorbent test have connect with its initial water content.In short time of the soilcolumn experiment, the effect is more obvious to the soil near the water side with the timeincreases, then the water in the soil move to the lower part from the distant part, and thewater content is less than the initial moisture content. The stress-strain curve are strainhardening in triaxial compression test, and it can be divided into three stages. Shall variableof the soil is smaller in conventional triaxial compression test than that in reduced triaxialcompression test, and it have a smaller volume contraction phenomenon. Shedding fromdifferent water content triaxial compression test can be seen, the water plays a crucial role onloess, and the greater the water contains, the lower the soil strength.2）Select a profile of the landslide in the direction of the main slide, we can obtained bynumerical simulation as follow: The original slopes appear the shape of the steady state,when the foot of the slope excavation, it will has a significant change in the main stress andthe shear strain and the x-direction displacement and velocity, the the toe of the landslipappear stress concentration. It was enhanced by the role of the heavy rain, and the slopestability factor changed to less than1, show thar the slope was in the destruction. 3）On the basis of the above analysisand the development of comprehensive landslidethat mechanical causes of the excavation of loess landslide mechanism is mainly: after theexcavation of the slope foot, the stress will redistribute in slope, The shear stressconcentrated in toe of the slope and the tensile stress concentrated in top of the slope. With thecontinued progress of the excavation, the slope limit equilibrium state is reached, with thesudden rainstorm induced, eventually leading to the occurrence of landslides.