本文關(guān)鍵詞： 云南紅土 干濕循環(huán) 水分遷移特性 含水率-干密度-溫度影響 裂縫發(fā)展特性 微結(jié)構(gòu)特性 裂縫發(fā)展機(jī)理　出處：《昆明理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：本文以極端氣候?qū)υ颇霞t土的影響為研究背景,以云南紅土為研究對(duì)象,提出了“干濕循環(huán)下云南紅土的裂縫發(fā)展研究”的課題�？紤]初始含水率、初始干密度、試驗(yàn)溫度和干濕循環(huán)次數(shù)等因素的影響,通過(guò)垂直土柱遷移試驗(yàn)、干濕循環(huán)試驗(yàn)和微結(jié)構(gòu)試驗(yàn)結(jié)合圖像處理方法,研究不同影響因素下干濕循環(huán)紅土的水分遷移特性、裂縫發(fā)展特性、微結(jié)構(gòu)特性及裂縫發(fā)展機(jī)理。該研究成果對(duì)于有效防治云南紅土地區(qū)的裂縫問(wèn)題具有重要的參考價(jià)值。干濕循環(huán)下紅土中的水分遷移特性表明:增濕條件下,紅土中的水分遷入量隨初始干密度和初始含水率的增大而減小;脫濕條件下,紅土中的水分遷出量隨初始干密度的增大而減小,隨初始含水率的增大保持不變;干濕循環(huán)條件下,紅土中表層含水率降低、內(nèi)部含水率升高,干密度減小。干濕循環(huán)下含水率對(duì)紅土裂縫發(fā)展的影響表明:增濕過(guò)程中,紅土樣產(chǎn)生裂縫,初始含水率越高的紅土樣越早產(chǎn)生裂縫;脫濕過(guò)程中,初始含水率越大的紅土樣裂縫越顯著;裂縫數(shù)量、長(zhǎng)度和面積與初始含水率正相關(guān);裂縫寬度存在峰值,隨初始含水率的增加先增大后減小。干濕循環(huán)下干密度對(duì)紅土裂縫發(fā)展的影響表明:增濕過(guò)程中,紅土樣產(chǎn)生裂縫,初始干密度越高的紅土樣越早產(chǎn)生裂縫;脫濕過(guò)程中,初始干密度越大的紅土樣裂縫越顯著;干濕循環(huán)中,裂縫數(shù)量、長(zhǎng)度和面積隨初始干密度的增大而增大,隨初始干密度的增大裂縫寬度先增大后減小;初始干密度越大的紅土樣膨脹穩(wěn)定時(shí)間越長(zhǎng)。干濕循環(huán)下溫度對(duì)紅土裂縫發(fā)展的影響表明:溫度越高的紅土樣產(chǎn)生裂縫的循環(huán)次數(shù)越少;試驗(yàn)溫度低時(shí)無(wú)裂縫產(chǎn)生,隨試驗(yàn)溫度的升高紅土樣在增濕中產(chǎn)生裂縫,溫度進(jìn)一步升高時(shí),紅土樣在脫濕中開裂;裂縫數(shù)量、長(zhǎng)度和面積與溫度正相關(guān),裂縫均寬在增濕中與溫度正相關(guān),脫濕中先增大后減小;在干濕循環(huán)中裂縫特征參數(shù)波動(dòng)上升。干濕循環(huán)下紅土的微結(jié)構(gòu)特性表明:干濕循環(huán)前紅土樣顆粒連接方式為片架結(jié)構(gòu)與片堆結(jié)構(gòu)同時(shí)存在,干濕循環(huán)后紅土樣的顆粒連接方式由片架結(jié)構(gòu)向片堆結(jié)構(gòu)轉(zhuǎn)變;隨初始含水率、初始干密度和溫度的升高土顆粒的片架結(jié)構(gòu)減少,片堆結(jié)構(gòu)增加;干濕循環(huán)后紅土樣的孔隙比增大、顆粒數(shù)增加、圓形度降低,分維數(shù)和定向度的變化與初始干密度和初始含水率有關(guān)。干濕循環(huán)下紅土裂縫的發(fā)展機(jī)理:干濕循環(huán)對(duì)紅土裂縫的作用機(jī)理可以從雙電層理論、土壤膠體理論、膨脹力、水分子動(dòng)能四個(gè)作用來(lái)解釋,其綜合作用導(dǎo)致了紅土樣的開裂現(xiàn)象;含水率升高、干密度增大和溫度上升放大了干濕循環(huán)對(duì)紅土的劣化作用,使裂縫發(fā)展周期縮短;根據(jù)裂縫的發(fā)展過(guò)程,可以將裂縫發(fā)展分為裂縫孕育期、裂縫產(chǎn)生和擴(kuò)展期、裂縫穩(wěn)定期3個(gè)階段。
[Abstract]:The impact of extreme weather on Yunnan clay as the research background, taking Yunnan clay as the research object, put forward the "research" the development of cracks of Yunnan red clay under cyclic wetting drying problem. Considering the initial water content, initial dry density, the influence factors of test temperature and wetting cycles, the vertical soil column migration test, image processing method combining the dry wet cycle test and microstructure test, effects of different factors on the migration characteristics under cyclic wetting and drying red water, the characteristics and development of cracks, micro structure characteristics and development mechanism of crack. The crack problem of the research results for the effective prevention and treatment of red soil in Yunnan region has an important reference value. The result showed that water migration characteristics of wet dry cycles in laterite the wet conditions, the water in the clay migration with initial dry density and initial water content decreased; desorption conditions, soil moisture in red The migration quantity density increases with the decrease of the initial dry, with initial water content increased unchanged; cyclic wet dry conditions, surface water reducing rate in laterite, the internal moisture content increased, dry density decreases. Under cyclic wetting drying effect of moisture content on the clay crack development showed that the humidification process of cracks in clay. The higher the initial moisture content of the clay samples early cracks; dehydration process, initial moisture content of clay samples larger cracks significantly; fracture number, length and area and initial water content are positively correlated; the crack width has a peak value, the first increase with the initial water content and then decreases. Under the cycle of dry and wet dry effect of density on clay crack development showed that the humidification process of cracks in clay samples, initial dry density and higher clay like the earlier cracks; during the drying process, the initial dry density is large crack like laterite is significant; dry wet cycle In the fracture number, length and area density increases with the increase of the initial dry density, the crack width increases first and then decreases with initial dry; the initial dry density is large laterite. The longer the steady expansion of samples showed that the effect of temperature on clay under cyclic wetting drying crack development cycles: the higher the temperature of the clay samples cracks less; no cracks test at low temperature, cracks in the wet clay samples with elevated temperature, temperature rises further, like in laterite dewetting cracking; crack number, length and area was positively correlated with temperature, cracks are wide in humidity and temperature are related, dehydration in the first increases and then decreases; in the dry wet cycle in the crack characteristic parameters of wave rise. Results show that the micro structure characteristics of clay under cyclic wetting drying: wet and dry cycle before clay like particles connection structure frame and sheet pile structure exist at the same time, dry After the red wet cycle like particles connection from the frame structure to stack structure transition; with the initial water content, reduce the rack structure of the initial dry soil increased particle density and temperature, stack structure increased; after dry wet cycles like laterite void ratio increases, the increase in the number of particles, the round of changes with the fractal dimension and the orientation of the initial dry density and initial water content. The development mechanism of clay crack under cyclic wetting drying mechanism of dry wet circulation on the clay cracks from the double layer theory, soil colloid theory, expansion force, water molecular kinetic energy four to explain the role, the comprehensive effect leads to the cracking phenomenon of laterite the sample; the increase of water content, dry density increase and temperature rise amplifies the deterioration effect of dry wet circulation on the clay, the crack development cycle shortened; according to the development process of the cracks, cracks can be divided into the incubation period of crack development, crack The formation and expansion period of the seams, the 3 stages of the fracture stabilization period.

【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU43

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