| As the ceaseless development of socioeconomy, continuous infrastructure construction has been implemented in all parts of the country to satisfy the human’s own survival and continuously increasing demand in superior life. Some of the constructions have made the various destruction to original ecological environment. Especially the construction of railway and highway, the exploitation and utilization of mineral resources, the building of water conservancy works and other large-scale infrastructure construction, which are not only disturbing the initial vegetation and making the vegetation cover reduce, but also destroying the structure and stabilization of original soil. All of these projects could promote landslide, debris flow and other natural disasters to product. While the environment problems and security problems could not be neglected, it seeks that the human and the nature could reach the real harmony.Although the soil itself has a certain compressive strength and shear strength, the tensile strength is very low. After some materials are added in the soil, which can not only strengthen the shear and compressive strength of soil, also can enhance the tensile strength of soil. Although the plant slope protection technology is widely applied in slope protection and engineering projects in recent years, but which is only limited to much practical application with the lack of oretical support. The research on the method of soil reinforcement and slope protection by plants is still at the exploratory stage. To provide a reasonably and completely theoretical basis for plant slope protection, taking the homogeneous soil slope as an example, choosing loess and the root of pine and locust as the study objects, this article studies on soil-reinforcement mechanism of forest roots. Making the soil strength decrease gradually with the finite element shear strength reduction method until the slope of undisturbed reaching the critical damage to the edge, calculating the sliding surface and the factor of safety by the finite element software ANSYS, and through the continuous simulation after forest root reinforcement anchoring, obtain the optimal rule of plantingSetting the loess slope of 15 degrees,30 degrees,45 degrees three kinds of conditions, choosing the ideal elastic-plastic constitutive model as the constitutive model of soil, assuming the deformation between roots and soil for root soil deformation coordination, because of the research of the paper slope is two-dimensional plane, according to the characteristics of different DP criteria, selecting DP4 criteria as the slope of the soil yield criterion. The heterogeneous soil slope stability before planting and after planting is proceed with calculation and analysis by strength reduction finite element and finite element analysis software ANSYS. Based on the guarantee of the steadiness of the slop, using the technology of plant slope protection, making a number of best practices regarding tree planting, and draw some conclusions, the results of the research were as follows:1.This paper presents the basic principles of plant roots to different bars and anchor-acting role and the role of soil mechanics theory slope. The theory and advantages of the application of finite element shear strength reduction method to the plant slope protection in projects of slope stability analysis, and combining the method with plant slope protection put forward the new theory basis for plant slope protection method.2. The stability of solid earth slope protection with forest root system is analyzed by ANSYS software. Then founding the ideal elastic-plastic constitutive model and the rule of DP4 is in the calculation accuracy range.3. With the increasing slope of loess, the minimum safety factor of soil stability decreases, reducing the stability of the slope, the probability of the occurrence of landslides is also growing.4.The calculation about the stability of forest root system shows that with the successive increase of the depth of the tree root, the slope stability is increasing by studying on the two kinds of woods about pinus tabulaeformis and robinia. Compared with other position planting the tree in slope angle is more conducive to improve slope stability.5. For slope stability contribution only from the foot before the two trees are more obvious with slope gradient of 25°, the best tree of robinia pseudoacacia and pinus tabulaeformis distance were 3.5m and 3m; The three trees of robinia pseudoacacia and the four trees of pinus tabulaeformis for slope stability contribution are obvious with slope gradient of 35°, the best distance of robinia pseudoacacia and pinus tabulaeformis were 3m and 2.5m; The four trees of robinia pseudoacacia and the five trees of pinus tabulaeformis for slope stability contribution are obvious with slope gradient of 45°, the best distance of robinia pseudoacacia and pinus tabulaeformis were 2.5m and 2m. |
