Study On The Mechanicals Of Loess Landslide Based On Breakage Mechanics

The Loess Plateau is an important area for human activities. There are a lot of different formations,different sizes, different shapes, different scales, different periods and different mechanical properties ofjoints, cracks, etc, in Loess, which are on behalf of breakage characteristics of loess. Not only it breakedthe wholeness soil mass, but also became it a fast track for water. At the same time,water sensitivitydamages the loess and loess landslide caused by the water and the breakages.It is comprehensively reviewed the engineering classifications of Loess landslide. Then a new type ofloess landslide is proposed. The slip surface of the new type of landslide is situated among the siltyclaydeposited in the ancient Lake in Wuqi conty. The clay content of the siltyclay is more than that of theoverlying loess. But the sand content of the siltyclay is more than that of red clay. All of these propertiesbring to better water aquitard and apt to slide. What is more to the point, the layer of the deposited siltyclaycontrols most large loess landslides in Wuqi area.By grading analysis of the loess sample, it is revealed that silty contents are dominated. But thecontents of the sand grains are similar to the clay contents. Combining with borehole data and geotechnicaltests, it is analyzed of variation of physical properties of the loess layer with depth.Combining Field survey with in-situ testing and laboratory direct shear test, ring shear test, themacroscopic characteristics of shearing loess are analyzed, such as surface scratches. On the other hand,micro-characteristics of shearing loess are analyzed by making use of electron microscopy scanning. Thetest results indicate the residual shear strength of shear strength is lower than the nature one. And thesaturated shear strength shear strength value is much lower than natural demonstration of water a largeinfluence on the strength of loess. Among different depths, different shear behaviors of loess with differentwater content are attributed.Based on the breakage mechanics, advanced by Shen Zhujiang, comparing binary medium model forloess, structural soil shear strength and shear strength of unsaturated loess, the loess shear strength can berepresented as three parts: the cohesion strength of the bonded blocks, the friction strength of the bondedblocks, and friction strength of weakened bands. The bonded blocks are damaged from the edge to theinner. Finally they are broken to be weakened bands, and the weakened bands are extended to be somebreakage surfaces. Adjustment of stress and strain illustrates the characteristics of loess shearing damage. The concept of breakage loess is advanced. Furthermore, a shearing geological model of breakage loess isestablished. Therefore two types of shear breakage mechanism of loess landslide, part-weakening ofshearing strength and part-concentrating of shearing stress, are advanced to analyze shearing failure ofLoess slope. At last, they are simulated by FLAC.As a conclusion, breakage characteristics and water sensitivity of loess are interaction and mutualpromotion. They may be the main factors to cause loess landslide.