The stability analysis and evaluation is the base of the landslide prevention, at the same time have improvement guidance to the landslide prediction. Divided the Chinese landslide stability analysis of research history into three stages:①experience analysis and evaluation stage;②half experience and semi theoretical analysis and evaluation stage;③theoretical development and the deeping stage. Described the research situation,trend and existing problems of the slide stability analysis and evaluation,get a clear conclusion,put forward my own understanding.

Paleosol is an important factor affecting the stability of loess slope, and its mechanical properties, deformation and failure mechanism are still under in-depth exploration and research. Here based on the GDS Lab System, using equivalent sine wave progressively loading mode of strain controlling, in order to reveal the dynamic strength characteristics of Paleosol under the vibration effect. The result show that:① there is an obvious phenomenon of stress relaxation during the cyclic loading test on Paleosol; Paleosol is high-consolidated clay, when the given confining pressure less than the natural confining pressure, the degree of stress relaxation increased at first and then decreased,to the contrary first decreased and then increased.② under the 50kPa、80kPa、100kPa confining pressure, the dynamic failure stress of Paleosol is 0.176kN、0.2302kN、0.2555kN,the dynamic failure stress increases linearly with the increase of confining pressure. The correlation coefficient is 0.9009 and the linear regression equation is бd=0.001б3+0.0958.③ On the basis of Molar Coulomb failure criterion, We obtained the index of dynamic strength of Paleosol, which was C=25.63kPa and φ=14º, by Molar Circle. In comparison with the static strength, the internal friction angle and cohesion decreases significantly, show that the Paleosol have obvious characteristic of brittle.

In the landslide disaster control and high slope strengthening engineering, anti-slide pile is one of trusted engineering measures, but cognition in aspect of forced state on the anti-slide pile, the pile-soil mechanism etc, which should be strengthened. Therefore, monitoring objects with three cantilever anti-slide pile entities in the loess high slope somewhere, burying monitoring instruments such as earth pressure cells and steel bar meter, for as long as 18 months of monitoring. Through analysis of monitoring results, can draw the following conclusion:①The soil pressure distribution form before the anti-slide piles is parabola-shape as a whole, whatever above the slip surface or under the slip surface the soil pressure distribution form behind the anti-slide piles is almost triangle as a whole;②The anti-slide piles construction are completed, pile-soil interaction force and reinforced by stress reaches stability in about 16 months;③A maximum soil pressure before the anti-slide piles on the ground, the soil pressure behind the anti-slide piles near the potential sliding surface;④Before the anti-slide piles and behind the anti-slide piles, reinforced by stress from pile cap to pile bottom respectively is "compressive stress and tensile stress" and "compressive stress, tensile stress and compressive stress, tensile and compressive stress of zero before pile is tensile stress value maximize after pile.

China covers an area of 9.6 million square kilometers, of which mountains and hills account for 65 percent[1]. As a result, a large number of economic construction need to be done in the mountain. However, because of its special nature and geological conditions, different types of landslide hazard phenomenon often occurred in the construction which seriously restricted the rapid development of the regional economy. Therefore, the author takes Lanzhou city, Gansu province which is the typical mountain town as an example to analysis of the types, characteristics, causes and prevention measures of the landslide hazards in the cities and towns construction, which can be for reference by similar areas.

Through the detailed investigation of Hejiacao landslide in Zhen'an county, this paper analysed the developing features and forming factors of the trench landslides, Meanwhile, it preliminarily discusses the mechanism of deformation and failures for the trench landslide. The investigation shows that: 1The trench landslide is special in shape, mainly in pushing type with low angle, and has characters of slow creep speed and long time. It mainly takes place in populated regions with serious damage; 2The trench landslide is controlled by many factors, such as trench terrain, poor lithology, hydrologic condition and human activities; 3The trench landslide experiences three phases: Deposition-crack, pushing-creep and final destruction in the process of forming and movement.