發(fā)布時(shí)間：2018-05-08 06:47

  本文選題：干濕循環(huán) + 云南紅土��； 參考：《昆明理工大學(xué)》2017年碩士論文

【摘要】：本文針對(duì)云南地區(qū)紅土愈發(fā)嚴(yán)重的干濕循環(huán)問(wèn)題,以云南紅土為研究對(duì)象,以干濕循環(huán)為控制條件,以不同影響因素下紅土的宏微觀特性為基礎(chǔ),結(jié)合理論分析,研究干濕循環(huán)條件下飽和紅土的剪切特性、非飽和紅土的土-水特性及土-水作用機(jī)理,對(duì)于有效解決紅土地區(qū)日益嚴(yán)重的災(zāi)害問(wèn)題具有重要意義。飽和紅土的三軸剪切試驗(yàn)表明:隨干濕循環(huán)次數(shù)和干濕循環(huán)幅度增加,飽和紅土的應(yīng)變軟化現(xiàn)象增強(qiáng),剪切峰值及其剪切破壞應(yīng)變、黏聚力和內(nèi)摩擦角、電導(dǎo)率都減小,初始變形模量、孔壓峰值增大,微結(jié)構(gòu)受損程度加深:結(jié)構(gòu)變松散,紅土顆粒破碎,孔隙變分散。隨初始干密度增大,飽和紅土的剪切峰值、初始變形模量、黏聚力和內(nèi)摩擦角、電導(dǎo)率都增大,剪切破壞應(yīng)變、孔壓峰值減小,微結(jié)構(gòu)受損程度減輕:結(jié)構(gòu)變緊密,孔隙明顯變小、變少。初始干密度對(duì)飽和紅土剪切特性的影響最明顯,干濕循環(huán)次數(shù)次之,干濕循環(huán)幅度的影響最小。隨排水條件UU、CU、CD依次變化,飽和紅土的應(yīng)變軟化現(xiàn)象越顯著,剪切峰值、剪切破壞應(yīng)變、初始變形模量、電導(dǎo)率都增大,黏聚力大小為:cuuccu≈ccd≈0,內(nèi)摩擦角大小為:φcdφcuφuu≈0,有效黏聚力大小為:c'uuc'cu≈c'cd≈0,有效內(nèi)摩擦角大小為:φ'cd≈φ'cuφ'uu≈0,孔壓峰值大小為:uf,uuuf,cuuf,cd=0,微結(jié)構(gòu)受損程度減輕:整體結(jié)構(gòu)變密實(shí),孔隙減少。非飽和紅土的土-水特性試驗(yàn)表明:隨初始干密度增大,紅土的進(jìn)氣值增高,脫水及吸水斜率、殘余含氣量減小,殘余含水量、電導(dǎo)率增大,微結(jié)構(gòu)呈現(xiàn)出結(jié)構(gòu)更密實(shí)、孔隙減少的特征。隨初始含水率增大,紅土的進(jìn)氣值降低,脫水斜率、電導(dǎo)率增加,微結(jié)構(gòu)表面形態(tài)從粒狀向板狀轉(zhuǎn)變,紅土顆粒輪廓及孔隙邊緣越模糊。隨預(yù)固結(jié)壓力增大,紅土的進(jìn)氣值增高,脫水斜率減小,殘余含水量、電導(dǎo)率增加,微結(jié)構(gòu)受損程度減輕:結(jié)構(gòu)越密實(shí),微觀界面越平整,紅土顆粒排列越規(guī)則且輪廓越模糊。隨粒徑增加,飽和后紅土的含水率增加,進(jìn)氣值降低,脫水及吸水斜率、殘余含氣量增加,殘余含水量減小,電導(dǎo)率先增加后減小,微結(jié)構(gòu)受損程度加深:微觀界面越起伏不平,顆粒排列越不規(guī)則,孔隙越大且不均勻。干濕循環(huán)過(guò)程中存在滯后現(xiàn)象,粒徑比干密度的影響更明顯。初始干密度、預(yù)固結(jié)壓力、粒徑(d=0.5mm除外)不同時(shí)可統(tǒng)一采用冪函數(shù)作為云南紅土的土-水特性擬合模型,初始含水率不同時(shí)采用線性函數(shù)。干濕循環(huán)下飽和紅土與水的作用:包括脫濕過(guò)程中水的逃逸作用、紅土顆粒的吸附作用、紅土體的硬化作用及收縮作用和吸濕過(guò)程中水的楔入作用、潤(rùn)滑作用、軟化作用及紅土體的膨脹作用,干濕循環(huán)過(guò)程中上述作用不斷加深加劇,嚴(yán)重?fù)p傷了紅土體的微結(jié)構(gòu),紅土導(dǎo)電能力也不斷改變,最終改變了飽和紅土的剪切特性。干濕循環(huán)下非飽和紅土與水的作用除了與上述作用有關(guān)以外,還與毛細(xì)作用、氣相的流動(dòng)作用和擴(kuò)散作用關(guān)系緊密,最終體現(xiàn)在基質(zhì)吸力與含水率的變化關(guān)系中。
[Abstract]:This paper aims at the dry and wet circulation of red soil in Yunnan area. Taking Yunnan red soil as the research object, taking the dry and wet cycle as the control condition, based on the macro and micro characteristics of the red soil under different influence factors, the shear characteristics of the saturated laterite under dry and wet conditions, the soil water characteristics of unsaturated laterite and soil water are studied. The three axis shear test of saturated red soil shows that the strain softening phenomenon of saturated red soil increases with the increase of dry and wet cycle times and the amplitude of dry and wet cycle, the peak shear peak and the shear breaking strain, cohesive force and internal friction angle, and the conductivity decrease. When the initial deformation modulus, the peak value of pore pressure increases, the damage degree of the microstructure is deepened: the structure becomes loose, the red soil particles are broken and the pores are dispersed. With the increase of the initial dry density, the peak shear peak, the initial deformation modulus, the cohesive force and the internal friction angle, the conductivity all increase, the shear failure strain, the pore pressure peak decrease, and the damage degree of microstructures is reduced. The effect of the initial dry density on the shear characteristics of saturated laterite is the most obvious. The dry and wet cycle times are the most obvious, the dry and wet cycle is the least. The UU, CU and CD changes with the drainage conditions, the more significant the strain softening phenomenon of the saturated laterite, the shear peak value, the shear failure strain, the initial deformation modulus, the conductivity. The cohesion size is increased, the cohesive force size is: cuuccu CCD 0, the internal friction angle is: Phi CD Phi Cu UU 0, the effective cohesive force size is 0, the effective internal friction angle is 0, the effective internal friction angle is: [Phi]'cu phi'uu 0, the size of the pore pressure peak is: UF, uuuf, the pore decreases. Soil water characteristics test showed that with the increase of initial dry density, the intake value of the red soil increased, the dehydration and water absorption slope, the residual gas content decreased, the residual water content, the conductivity increased, the microstructure showed more dense structure, and the porosity decreased. With the increase of initial water content, the intake value of the red soil decreased, the slope of dehydration, the electrical conductivity increased, microjunction. With the increase of pre consolidation pressure, the intake value of the red soil increases, the slope of the dehydration decreases, the residual water and the electrical conductivity increase, and the damage degree of the microstructures decreases with the increase of preconsolidation pressure. The more dense the structure is, the more smooth the microstructure is, the more regular the arrangement of the laterite particles and the blur the contour. The water content of the red soil increased, the water content of the red soil increased, the intake value decreased, the dehydration and water absorption slope, the residual moisture content increased, the residual water content decreased, the electrical conductivity increased first and then decreased, and the damage degree of the microstructures was deepened: the more irregular the micro interface was, the more irregular the particle arrangement, the larger the pore and the unevenness. There was a lag in the dry and wet cycle. The effect of particle size is more obvious than dry density. Initial dry density, preconsolidation pressure, particle size (except d=0.5mm) can not simultaneously use power function as a fitting model of soil water characteristics of Yunnan red soil. The initial water content does not use linear function at the same time. The effect of saturated red soil and water under dry and wet cycle, including the escape effect of water during dehumidification process The adsorption of red soil particles, the hardening of the red soil and the wedge action of the red soil, the wedge action of the water, the lubrication, the softening and the swelling of the red soil during the process of moisture absorption, the effects of the red soil in the dry and wet cycle aggravated, and the microstructure of the red soil was seriously damaged, and the conductivity of the red soil was constantly changed, and finally the satiety was changed. The effect of unsaturated laterite and water under dry and wet cycle is closely related to capillary action, gas flow and diffusion, which is finally reflected in the change of matrix suction and water content in the action of unsaturated laterite and water under dry and wet cycle.

【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)】：TU446

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本文編號(hào)：1860377