Study On Erosion And Soil Stabilizer Properties For Highway Subgrade Slope

Subgrade slope surface erosion is defined as a phenomenon which rain runoff destroys subgrade slope surface, and washes away soil on the surface of slope. It is the most common problem in the field of highway. However, it is studied insufficiently. And only a few research work is reported in the literature. In this paper the author tries to perform a comprehensive and systematical study on the erosion influence factors, erosion commencing conditions, scouring force of runoff and evaluation methods for slope erosion stability of highway subgrade slope. Based on large amount of tests, the author also tries to develop researches on properties of soil stabilizing materials for subgrade slope. The main results are summarized in what follows:(1) A classification method for subgrade slope erosion is established according to the following four factors: a) the shape feature of the scouring trace and the scouring phases, b) the moving style and feature of the slope soil, c) different protection measurements on slope surface, and d) amount of the scouring soil.(2) Erosion influence factors on highway subgrade slope are analysed and studied systematically. The determination methods of erosion critical gradient are discussed carefully. Theoretical formulation of rain permeation on slope is set up. A train of ideas based on stabilizing the soil properties is purposed to improve the erosion stability on subgrade slope.(3) The force features of soil on slope surface during scouring process are summarized. A theoretical formulation of incipient motion drag force is developed for the uniform, non-clayed soil subgrade slope; and the non-uniform, non-clayed soil subgrade slope; as well as the clay soil subgrade slope. At the same time, the erosion commencing conditions of subgrade slope, and the energy exchange and balance of erosion process on raindrop spattering and runoff scouring are studied. Also, formulations of the runoff sediment-carrying capability on slope bed load and suspended load are derived. Theoretical discussions for the occurrence and development of erosion on highway subgrade slope are given.(4) A fuzzy evaluation method is purposed and established to assess the slope erosion stability. The evaluation indexes of erosion stability are discussed deeply. The numerical methods of these evaluation indexes are set up. The determination method and selecting program are founded. The author uses this method to...