| Extensible soil is a kind of highly plastic clay widely distributed in all parts of the world.It has strong water sensitivity,so it has the special properties of swelling in water absorption and shrinking in water loss.When the soil moisture in expansive soil slope changes,it will cause the slope to slip gently and slip shallow.The reason of this harm is that the soil of expansive soil slope has experienced serious dry-wetting cycle.Usually when expansive soil is encountered,other soils are used to replace expansive soil,and expansive soil becomes a waste resource.Generally speaking,the soil properties of expansive soils are not suitable for plant growth.Therefore,expansive soil slope is mostly exposed in nature.When the exposed slope experiences rainfall,the rainwater will directly infiltrate into the soil of the slope,resulting in the increase of moisture content of the soil and the hidden danger of slope instability.In this thesis,the concept of ecological slope protection was introduced into the expansive soil slope protection,and the expansive soil was used as the slope protection base material for ecological improvement.The influence of expansive soil as the slope protection base material on the moisture content in the soil body of expansive soil slope during rainfall was explored.The main work is as follows:(1)Material selection of improved expansive soil.By understanding the relevant materials that constitute the slope protection substrate at present,analyzing the function of the materials and considering the purpose that the improved expansive soil is not suitable for plant growth,cement,vegetation concrete greening additive,ecological fertilizer,humus,plant fiber,plant seed and so on are finally selected as the materials of the improved expansive soil.(2)The expansive soil planting experiment was established.Bermudagrass and Indigofera amblyantha Craib were selected as the research objects to explore the effects of different amounts of cement,vegetation concrete greening additives and the same amount of rotten peanut shell,chicken manure,dry water moss powder and other materials on the growth of bermudagrass and Indigofera amblyantha Craib.The results showed that when the content of cement was 5% and the content of vegetation concrete greening additive was 50% of cement,the germination number and average growth height of the seeds reached the maximum,and the whole substrate had the effect of promoting the growth of plants.At this point,the p H value of the substrate drops to the range of 7.3 to 8.2,and the substrate’s acidity and alkalinity also meet the growth requirements of the plant.(3)The model test of expansive soil slope was established,and the control test of rainfall was carried out through the slope with vegetation and the slope without vegetation with exposed slope with expansive soil modified substrate.Under different intensity of natural rainfall,the soil moisture content of slope with vegetation is lower than that of slope without vegetation.The vegetation on the slope intercepts the rainwater through the foliage stem,reduces the infiltration amount of rainwater in the slope,weakens the impact force of rainwater falling on the slope,reduces the soil loss on the slope,plays the effect of controlling soil erosion,enhances the ability of the slope to resist rainwater erosion,and indirectly ensures the stability of the slope. |
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