| Because of its unique geological features and climate characteristics, the Pisha sandstone region is called as“the maximum of soil and water loss”. Base on the objective of exploring slope erosion rules and reinforcement effect of EN-1 solidified agent to improve scour stability of slope in the region, combining the research methods of natural slope scouring test, laboratory soil engineering test and artificial simulation slope scouring test, taking the study on influencing factors of slope scour stability as the premise, analyzed the influence of EN-1 on engineering mechanical characteristics and simulated slope resistance to scour of Pisha sandstone weathered soil, elected the appropriate EN-1 content, curing age, compaction degree and soil water content of solidified slope in the region. Got the following progress:1. Current scour and slope gredient are the main factors that influence on scour stability of Pisha sandstone natural slope. Runoff intensity, sediment yield intensity and runoff sediment concentration increased with the increase of scour flow. Runoff intensity, sediment yield intensity and runoff sediment concentration of gray yellow Pisha sandstone first increased, then decreased with the increase of slope gredient, and the critical slope was 25°. Runoff producing and sediment yield indexes of gray white and red brown Pisha sandstone increased with the increase of slope gredient. Flow velocity increased with the increase of scour flow and slope gredient. The movement patterns of slope runoff were laminar flow under the scour flows and slope gredients in this experiment. The flow regimes were subcritical flow when scour flows and slope gredients were smaller, conversely, were supercritical flow. Runoff drag coefficient(f) of grey yellow and red brown Pisha sandstone decreased with the increase of scour flow, f of grey white Pisha sandstone increased with the increase of Scour flow. f of grey yellow Pisha sandstone presented the tendency that first increase, then decrease with the increase of slop gradient, f of grey white and red brown Pisha sandstone increased with the increase of slop gradient. Runoff shear stress, runoff power and runoff kinetic energy theory could explain the runoff sediment process of Pisha sandstone natural slope to varying degrees. Runoff drag coefficient, hydraulic radius, runoff power and runoff kinetic energy had bigger contribution to sediment yield of Pisha sandstone natural slope. 2. Vegetation coverage could obviously increase scour stability of Pisha sandstone natural slope. The size order of runoff intensity of Pisha sandstone natural slope were as follows: bare land>Chinese pine>grass land>korshinsk peashrub>seabuckthon. The size order of sediment yield intensity and runoff sediment concentration were as follows: bare land>grass land>korshinsk peashrub>Chinese pine>seabuckthon. Relative to grass land, korshinsk peashrub and Chinese pine, runoff and sediment reduction effect of Pisha sandstone natural slope of seabuckthorn coverage were biggest.3. EN-1 content, curing age, compaction degree and soil water content are the main factors that affect the characteristics of compaction, shear strength and impermeability of solidified soil. EN-1 had less influence on soil optimum moisture content of Pisha sandstone weathered soil, but could effectively improve the maximum dry density. The shear strength and impermeability of Pisha sandstone plain and solidified soil increased with the increase of compaction degree, the shear strength decreased with the increase of water content. The shear strength and impermeability improved significantly with the increase of EN-1 content and curing age.4. Current scour, slope gredient and compaction degree are the main factors that influence on scour stability of Pisha sandstone simulated slope. Runoff intensity increased with the increase of scour flow and compaction degree, slope gredient had no significant effect on runoff intensity. Sediment yield intensity and runoff sediment concentration increased with the increase of Scour flow, decreased with the increase of compaction degree, first increased, then decreased with the increase of slope gredient, the critical slope of yellow green and grey yellow Pisha sandstone were 60°and 50°. Flow velocity increased with the increase of scour flow, slope gradient and compaction degree. The movement patterns of slope runoff were turbulent flow when scouring proceeded to the later period at bigger scour flows and smaller compaction degrees. The movement patterns of slope runoff were all laminar flow at other treatments. The flow regimes were subcritical flow when scouring proceeded to the later period at smaller compaction degrees. The flow regimes were all supercritical flow at other treatments. f increased with the increase of Scour flow, decreased with the increase of compaction degree. f of Yellow green Pisha sandstone had tendency that first increase, then decrease with the increase of the slope gredient, and f of gray yellow Pisha sandstone had just the opposite trends with the slope gredient. Runoff shear stress, runoff power and runoff kinetic energy theory could explain the runoff sediment process of Pisha sandstone simulated slope at different scour fiow, slope gredient and compaction degree to varying degrees. 5. EN-1 content, curing age and compaction degree are the main factors that influence on scour stability of Pisha sandstone solidified slope. Runoff intensity increased with the increase of compaction degree, EN-1 content and curing age had no significant effect on Runoff intensity. Sediment yield intensity and runoff sediment concentration decreased with the increase of curing age and compaction degree, sediment yield indexes of yellow green Pisha sandstone first decreased, then increased with the increase of EN-1 content, and got minimum at 0.2% EN-1 content; sediment yield indexes of grey yellow Pisha sandstone decreased with the increase of EN-1 content. Flow velocity increased after adding EN-1, increased with the increase of compaction degree. Curing age had no significant effect on flow velocity. The flow regimes of Pisha sandstone solidified slop were all laminar flow and supercritical flow under the EN-1 content, curing age and compaction degree in this experiment. f decreased with the increase of curing age and compaction degree. f of yellow green Pisha sandstone first decrease, then increase with the increase of EN-1 content, f of grey yellow Pisha sandstone first increase, then decrease with the increase of EN-1 content. f had a positive correlation with sediment discharge rate. Runoff shear stress and runoff power theory could explain the erosion sediment yield process of Pisha sandstone solidified slope to varying degrees.6. Comprehensive consideration on EN-1 affection on shear strength, impermeability and scourresistance of Pisha sandstone weathered soil, in order to improve the ability of soil resistance runoff scour of slope in Pisha sandstone region, reduce the harm of soil and water losses in the region. Suggest optimum EN-1 content is 0.2%, curing age is at least 15 d above, controlling compaction degree above 95%, water content slightly less than optimum moisture content at project practice of EN-1 solidifying and protecting slope technology in the region. |
PDF Full Text Request