本文選題：全風(fēng)化膨脹巖　切入點：SEM　出處：《西南交通大學(xué)》2017年碩士論文

【摘要】：尖山營特大橋位于南北向川黔經(jīng)向構(gòu)造體系內(nèi)的一條緊密狀向斜構(gòu)造——昌明向斜——近核部地區(qū),隨當(dāng)?shù)卦�、雨季的氣候變化而異常升降。本文以此為研究背�?研究尖山營地區(qū)地表裸露的全風(fēng)化灰白色泥頁巖在荷載作用下的膨脹特性。本文選取初始含水率、干密度、初始加壓荷載值三個主要因素,分析研究區(qū)巖土體膨脹率、膨脹力在以上三個因素作用下的變化規(guī)律,建立膨脹力與初始含水率、干密度、初始加壓荷載間的關(guān)系。本文主要研究成果入下:通過微觀組構(gòu)分析,得到全風(fēng)化膨脹巖的鏡下主要呈片狀結(jié)構(gòu),礦物成分主要為伊利石,含量為90.4%,其次是石英,含量為9.6%。通過室內(nèi)基本土工試驗,得到全風(fēng)化擾動膨脹巖的無荷載膨脹率試驗,當(dāng)試樣的干密度較大時,土體的膨脹變形可明顯劃分為:初始緩慢膨脹、加速膨脹、后期穩(wěn)定膨脹階段三個階段;當(dāng)干密度較小時,初始緩慢膨脹階段與加速膨脹階段會合二為一。同時,干密度越大,試樣達到膨脹穩(wěn)定階段需要的時間越長。無論在任何含水率狀態(tài)下,試樣的變形量隨干密度的增大而顯著增大。初始含水率對無荷載狀態(tài)的一維膨脹速率的影響較干密度大。干密度對無荷載膨脹率大小的影響較含水率大。土體平衡膨脹力與干密度之間滿足指數(shù)關(guān)系,膨脹應(yīng)變與豎向應(yīng)力呈logistic函數(shù)關(guān)系。經(jīng)過7個判別指標(biāo)的評判結(jié)果,得出尖山營特大橋地表出露的全風(fēng)化膨脹巖屬于強膨脹巖。同時,自由膨脹率是對膨脹巖的分類與判別最為準(zhǔn)確與高效的一個指標(biāo)。結(jié)合針對全風(fēng)化膨脹巖的室內(nèi)宏、微觀試驗結(jié)果,經(jīng)過理論分析得出:全風(fēng)化膨脹巖的脹縮機理以擴散雙電層理論為主,晶格擴張理論為輔;原狀膨脹巖的膨脹機理考慮主要以晶格擴張為主。
[Abstract]:The Jianshanying Bridge is located in a tight syncline-Changming syncline-near-core area in the south- north Sichuan-Guizhou meridional structural system, which rises and falls abnormally with the local climate change in the early and rainy seasons.In this paper, the expansion characteristics of fully weathered gray-white shale exposed on the surface of Jianshanying area under load are studied.In this paper, three main factors of initial moisture content, dry density and initial compressive load are selected to analyze the variation law of expansion rate and expansion force of rock and soil in the study area, and to establish the expansion force, initial moisture content and dry density.The relationship between initial compressive loads.The main results of this paper are as follows: through microscopic fabric analysis, it is found that the weathered expansive rock is mainly flake structure under microscope, the mineral composition is mainly Illite, the content is 90.4 and the next is quartz, the content is 9.6.Through the basic geotechnical test in laboratory, the load-free expansion test of the total weathered disturbed expansive rock is obtained. When the dry density of the sample is high, the swelling deformation of the soil can be obviously divided into: initial slow expansion, accelerated expansion,When the dry density is small, the initial slow expansion stage and the accelerated expansion stage will be combined.At the same time, the larger the dry density, the longer it takes for the specimen to reach the stage of expansion and stability.Under any moisture content, the deformation of the specimen increases significantly with the increase of dry density.The effect of initial moisture content on the one dimensional expansion rate is greater than that of dry density.The effect of dry density on load-free expansion ratio is greater than that of moisture content.The relationship between the equilibrium expansion force and the dry density of the soil is exponential, and the expansion strain and the vertical stress are related to the logistic function.Based on the results of seven discriminant indexes, it is concluded that the fully weathered expansive rocks exposed on the surface of Jianshanying Bridge belong to strong expansive rocks.At the same time, the free expansion rate is the most accurate and efficient index for classification and discrimination of expansive rock.Based on the results of laboratory macro and micro tests, it is concluded that the expansion and shrinkage mechanism of fully weathered expansive rock is mainly based on diffusion double layer theory, supplemented by lattice expansion theory.The expansion mechanism of undisturbed expansive rocks is mainly considered by lattice expansion.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：U442.2

【參考文獻】

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本文編號：1729841