Research On The Effect Of The Biotechnical Slope Protection On The Shallow Stability

The biotechnical slope protection is the first way to prevent slope hazards and control soil loss, it also represent the developing direction of slope protection. Based on elastic mechanics, geotechnical engineering, percolation mechanics, and the results of lab and outdoor experiment, this paper studies the hydrologic effect and mechanical effect of the biotechnical slope protection, and their effect on slope stability. Major work and its characteristics are summarized as follows:(1)On the basis of the theory of rainfall infiltration, enhancement of precipitation infiltration by vegetation and its effect were systemically studied. It discloses the mechanism of interaction between enhancement of precipitation infiltration and control soil loss by vegetation, and the result of them is water and soil conservation. The study of the article shows that vegetation doesn't effect on rainfall infiltrating underside the root zone of vegetation cover slope, so there is on effect on deep seated stability of vegetation.(2)By elastic theory, and the load pressure condition of roots being considered after soil root complex shearing, the mechanical model of the additional cohesion of soil root complex provided by roots was established. The additional cohesion depended on the included angles between roots and shear belt, and the tension of roots. The mechanical model of reinforcement action for soil root complex provided by shallow roots of vegetation was confirmed with the results of experiment.(3)The process of infiltration into the vegetation slope due to rainfall and the distribution of pore water pressure were examined through numerical simulation analysis. It shows that herbaceous plant has little effect on pore water pressure. The reinforcement action for rock and soil slope bodies provided by herbaceous vegetation is remarkable, so herbaceous vegetation has no effect on deep seated stability.(4)An extended Mohr-Coulomb failure criterion was used to allow for the shear strength under the change of matric suction, to study the effect on shallow slope stability of the interaction hydrologic effect and mechanical effect. The result indicates that the reinforcement for shallow slope provided by herbaceous vegetation is investigated.From the above work, a systematic theory of the hydrologic effect and mechanical effect of the biotechnical slope protection and their effect was summarized, and the mechanical model of the additional cohesion of soil root complex provided by roots was established. It provides the theory of the application of biotechnical slope protection in slope protection, and it is important for making precise evaluation for expressway biotechnical slope protection.