【摘要】：硫酸鹽漬土作為一種特殊土,廣泛分布于世界各地區(qū),我國硫酸鹽漬土主要分布于西北地區(qū)。寧夏地處西北內(nèi)陸干旱-半干旱地區(qū),區(qū)域內(nèi)氣候干燥、蒸發(fā)強烈、溫差巨大,從而形成了特有的內(nèi)陸寒旱區(qū)鹽漬土,其中,硫酸與亞硫酸鹽饋土的分布較多。硫酸鹽漬土具有鹽脹、溶陷及腐蝕等特性,工程建設(shè)中這些特性的危害比濕陷性黃土還大。隨著西部大開發(fā)戰(zhàn)略及“一帶一路”的深入實施,在寧夏地區(qū)進行的水利、公路、鐵路及房建等工程會不斷增多,這必將遇到硫酸鹽漬土問題。因此,對硫酸鹽漬土工程特性的分析研究顯得特別的迫切與必要。本文選取寧夏吳忠市紅寺堡地區(qū)的硫酸鹽漬土作為試驗用的原料土,以室內(nèi)人工制備的硫酸鹽o,土為研究對象,就壓實度、含鹽量、含水率、溫度變化對硫酸鹽漬土強度、鹽脹、壓縮以及氯化鈣、粉煤灰改良硫酸鹽o,土鹽脹特性進行了試驗研究。通過研究得到以下結(jié)論:(1)壓實度與含水率在一定范圍內(nèi)對粘聚力有增強作用,但超過某個臨界值會降低粘聚力,含鹽量與凍融循環(huán)次數(shù)對粘聚力具有減小作用。各因素對粘聚力的影響較大,內(nèi)摩擦角受上述各因素的影響較小。(2)對于硫酸鹽o,土的鹽脹率,含鹽量影響顯著,其他因素影響不顯著,含鹽量對鹽脹率具有增大作用;對于壓縮系數(shù),含鹽量影響極顯著,凍融次數(shù)影響顯著,其他因素影響不顯著,含鹽量與凍融次數(shù)增加都會增大壓縮系數(shù)。(3)單側(cè)降溫條件下,硫酸鹽漬土的起脹溫度隨含鹽量增加而增大。隨溫度降低,鹽凍脹過程表現(xiàn)為四個階段:35～5℃之間屬于純鹽脹階段,5～5℃之間屬于調(diào)整階段,-5-10℃之間屬于鹽凍脹階段,-10～-25℃之間屬于穩(wěn)定階段。(4)通過常溫下改良硫酸鹽o,土鹽脹的試驗,得到粉煤灰的最優(yōu)摻量為20%,Cacl2的最優(yōu)摻量宜為2%,Cacl2對鹽脹的抑制效果較為明顯。本文通過對寧夏地區(qū)硫酸鹽o,土工程特性的室內(nèi)試驗研究,為硫酸鹽o,土地區(qū)的工程建設(shè)提供參考與技術(shù)支持。
[Abstract]:As a special soil, sulphate soil is widely distributed in all parts of the world, and sulphate soil is mainly distributed in northwest of China. Ningxia is located in the arid and semi-arid region of northwest China. Its climate is dry, evaporation is strong, and the temperature difference is huge, thus forming the special saline soil in the inland cold and arid region, among which, the distribution of sulfuric acid and sulfite fed soil is more. Sulfate saline soil has the characteristics of salt expansion, dissolution and corrosion, which are more harmful than collapsible loess in engineering construction. With the implementation of the strategy of western development and Belt and Road, the number of water conservancy, highway, railway and house construction projects in Ningxia will increase, which will inevitably meet the problem of sulphate saline soil. Therefore, it is urgent and necessary to analyze and study the engineering characteristics of sulphate saline soil. In this paper, sulphate soil in Hongsibao area, Wuzhong City, Ningxia was selected as the raw material soil for the experiment. The sulphate soil prepared in laboratory was taken as the research object. The strength of sulphate soil was affected by the change of compaction degree, salt content, moisture content and temperature. The characteristics of salt swelling, compression, calcium chloride and fly ash modified sulfate and soil salt swelling were studied. The conclusions are as follows: (1) compaction and water content can enhance the cohesion in a certain range, but beyond a certain critical value, the cohesion will be reduced, and the salinity and the number of freeze-thaw cycles will decrease the cohesion. Each factor has a great influence on the cohesion, but the angle of internal friction is less affected by the above factors. (2) for sulfate, the salt expansion rate of soil, the salt content has a significant effect, but the other factors have no significant effect, the salt content has an increasing effect on the salt expansion rate; For the compression coefficient, the effect of salt content is very significant, freezing and thawing times are significant, other factors are not significant, the increase of salt content and freeze-thaw times will increase the compression coefficient. (3) under the condition of unilateral cooling, The swelling temperature of sulphate saline soil increases with the increase of salt content. As the temperature decreases, The process of salt frost heaving shows four stages: 35 鈩，

本文編號：2265626