Research On Composite Method To Improve Expansive Soil For Ecological Restoration

Based on the theories of slope vegetation restoration, agrology, bionomics and soil mechanics, the vegetation restoration method after lime stabilizing of expressway expansive soil in Guangxi Province is studied by inside experiment, which called composite improvement. The danger of expansive soil to the construction is introduced briefly, the main properties of expansive soil are analyzed, and some commonly used improve method home and overseas are summarized; then the principle of lime-stabilized method is explained especially, also several suggestions to lime-stabilized method are proposed according to its insufficiencies, which are the contents and goal of our research.A series of laboratory experiments are done on representative samples of expressway from Guangxi with the goal of vegetation restoration, the method of ecological restoration to lime-stabilized soil is determined primarily. The same laboratory experiments are done and compared to lime-stabilized soil comprehensively, both advantages and disadvantages of the composite method are evaluated systemicly.The main achievements are as follows:(1) The lime stabilizing principle to expansive soil is explained through the content of clay mineral;(2) The type of Guangxi expansive soil is discerned to be the middling one according to authoritative discriminances home and overseas; 3%,5%,7%,9% are selected to be the four levels of lime ratio, and their effects are discussed individually in order to ascertain the quantitative relations between the ratio and the effects, the optimal mix ratio 5%-7% is gained according to this ultimately;(3) The research is conducted to pH value of lime-stabilized soil, which tells us: the pH value is increased with the lime ratio, but it becomes slowly after reached a peak value 12.4,that is identical with the empirical value, the lime-stabilized soil is defined as alkali soil;(4) Effective additives are found which can reduce the alkalinity of soil remarkably, they are physiological acidic fertilizers, gypsum and physiological...