Study On The Growing Laws And Controlling Measures For Loess Landslide

In order to suiting the mushrooming economic construction in vast loess area in our country, In this dissertation, loess landslide hazards in the loess (plateau) area are systematically studied to solve some questions, such as the categorization of loess landslide, the soil of sliding belt, the forming and movement mechanism, and their prevention and control measures.Based on the pluriennial productive practice and many loess landslide instances and their research productions from domestic and foreign, the loess landslide hazard is studied by the theories and methods, which has borrowed from geology engineering, geology, mechanics, physics, mathematics and economics. After 3 years struggle, some valuable results is obtained by advanced test instruments, optic apparatus and computer. The main new views and methods described as follows:1. A two-type and four-pattern scheme for categorizing loess landslide is presented.2. The distribution and development regularities of loess landslide are systematically summarized.3. The soil of sliding belt is categorized. And their physical, mechanical characteristics and the micro-structure are studied. Use clay soil of sliding belt as an example, the micro-structure change during the shear process is studied. And the mechanism is also analyzed by an example of saturated loess.4. The seasonal freeze-thaw inducing mechanism of loess landslide is studied. The soils temperature distribution on the slope surface and the freezing depth are modeled. And the loess landslide mechanism induced by rainstorm, engineering activity, or earthquake is also put forward.5. The creep stage and movement stage about loess landslide moving is established.6. Slide and casting out, dislocation and squeezing out, fault and stretching out are the movement ways of loess landslide. And the locus equation of loess landslide body is inferred under different movement ways.7. A three-segment model is established for loess landslide and its velocity analysis is carried out. The research conclusions are as follows: with a definite boundary condition, (a) If the angle of surface of rapture steepen by 5 ?, the slide velocity should increase 0.5m/s; (b) If the volume of anti-slide segment shrinks by 10%, the velocity should increase 0.06m/s; (c) The relationship between the soil strength of sliding belt and the slide velocity is linear and there is a threshold limit, e.g. the slide velocity increases linearly with the weakening of the soil strength, and if the cohesive strength is fixed, the velocity should increase 0.4m/s by diminishing the internal friction angle 4.5?,but when the soil of sliding belt lose its strength (idealcondition ) , sliding velocity will be biggest and the influence of soil of sliding belt will be utmost, i.e., the sliding velocity is would not change.8. The mathematic model to predict traveling distance of loess landslide whose surface of rapture is within or along the contact surface between the loess and the bedrock is established.9. Loess landslides induced by cutting are modeled by FLAC and DEM.10. Use three kinds of loess landslides as examples, the whole process of comprehensive control, the engineering mode, and the feasibility and effectiveness of prevention and control measures are demonstrated.11. From the point of economic view, an evaluation mode of economic benefits of the comprehensive control measures for loess landslide is filed out.