本文關鍵詞： 水泥土 無側限抗壓強度 應力-應變關系 影響因素　出處：《西北農林科技大學》2015年碩士論文　論文類型：學位論文

【摘要】：隨著西北大開發(fā)的深入,在我國西北地區(qū)修建了大量的道路工程和水利工程。黃土是西北地區(qū)主要的建筑材料之一,然而由于黃土具有濕陷性、非飽和性、震陷性等特性,黃土的強度往往不能滿足實際建筑工程的需要,例如地基沉降和路基承載力問題。為了滿足工程要求,實際工程中一般摻入水泥、石灰等,對黃土進行改良。水泥土是以土為主要骨料,以硅酸鹽水泥為膠凝材料,以外加劑為改善其工程性能的補充添加物,以水為反應媒介所組成的混合物,經過拌和、振搗和養(yǎng)護而形成的具有特殊工程特性的堅硬材料。它具有抗壓強度高,抗凍、抗?jié)B、抗蝕和抗沖刷、耐久性能好等優(yōu)點,被廣泛用于路面基層、邊坡加固、防滲里襯、地基穩(wěn)定和夯土建筑的墻體材料中。本文依據前人的成果,以陜西延安安塞玉泉寺水庫筑壩土料為加固對象,以無側限抗壓強度試驗為試驗方法,研究了水泥摻量、干密度、含水率、養(yǎng)護齡期和養(yǎng)護方式對水泥土無側限抗壓強度和應力-應變關系的影響,得出了以下結論。(1)隨著水泥摻量的增加,水泥土的最大干密度和最優(yōu)含水率都有很小幅度增加,而且水泥土的無側限抗壓強度呈線性增長。在同樣水泥摻量的條件下,隨著干密度的增加,水泥土無側限抗壓強度呈線性增長;隨著含水率的增加,水泥土無側限抗壓強度呈二次函數形式衰減;隨著養(yǎng)護齡期的增長,水泥土無側限抗壓強度呈冪函數形式增長。(2)水泥土應力-應變關系曲線都可分為壓密階段、彈性階段、塑性強化階段和應力衰減階段4個階段;水泥摻量和養(yǎng)護齡期的增加能夠減小水泥土的彈塑性變形;干密度和含水率的增加能夠增加水泥土的彈塑性變形。(3)采用不同組合鹽溶液(Na2SiO3、NaOH和Na2SO4)浸泡養(yǎng)護水泥土,通過改變3種溶質的組合方式,研究出對水泥土無側限抗壓強度增強最顯著的溶液組合。通過對正交試驗結果的極差分析和方差分析,確定了鹽溶液最優(yōu)組合為(Na2SiO3)3(NaOH)1(Na2SO4)2,也可稱為312溶液。(4)無論齡期如何變化,無側限抗壓強度由高到低的排序均為:312溶液浸泡養(yǎng)護→飽和石灰水浸泡養(yǎng)護→標準養(yǎng)護。312溶液浸泡養(yǎng)護和飽和石灰水浸泡養(yǎng)護水泥土試樣的強度隨著齡期的增加會趨于平緩。(5)標準養(yǎng)護下隨著養(yǎng)護齡期的增加水泥土彈塑性變形減小,脆性越來越明顯;312溶液浸泡養(yǎng)護可以增加水泥土彈塑性變形并提高其塑性,但會隨著齡期的增加其提高幅度會趨于平緩;飽和石灰水浸泡養(yǎng)護不能增加水泥土的彈塑性變形,但能維持水泥土的塑性保持不變。
[Abstract]:With the development of Northwest China, a large number of road projects and water conservancy projects have been built in Northwest China. Loess is one of the main building materials in Northwest China. However, loess has the characteristics of collapsibility, unsaturated property, earthquake subsidence and so on. The strength of loess often can not meet the needs of actual construction projects, such as foundation settlement and subgrade bearing capacity. The cement soil is a mixture composed of soil as main aggregate, Portland cement as cementitious material, admixture as supplementary additive to improve its engineering performance, and water as reaction medium. A hard material with special engineering characteristics formed by vibration and maintenance. It has the advantages of high compressive strength, anti-freezing, impermeability, corrosion and erosion resistance, good durability, etc., and is widely used in pavement base, slope reinforcement, impermeable lining, etc. In the wall material of foundation stabilization and rammed earth building, based on the achievements of predecessors, this paper takes the earth material of Ansai Yuquan Reservoir in Yan'an, Shaanxi Province as the reinforcement object, takes the unconfined compressive strength test as the test method, studies the content of cement and the dry density. The influence of moisture content, curing age and curing mode on the unconfined compressive strength and stress-strain relationship of cement-soil is obtained. The following conclusion is drawn: (1) with the increase of cement content, The maximum dry density and optimum moisture content of cement-soil increased slightly, and the unconfined compressive strength of cement-soil increased linearly. The unconfined compressive strength of cement-soil increases linearly; with the increase of moisture content, the compressive strength of cement-soil decreases in the form of quadratic function; with the increase of curing age, the unconfined compressive strength of cement-soil decreases in the form of quadratic function. The stress-strain relationship curves of cement-soil can be divided into four stages: compaction stage, elastic stage, plastic strengthening stage and stress attenuation stage. The increase of cement content and curing age can reduce the elastoplastic deformation of cement-soil, and the increase of dry density and moisture content can increase the elastic-plastic deformation of cement-soil. By changing the combination of three solutes, the solution combination, which can enhance the compressive strength of cement-soil without lateral limit, is studied, and the results of orthogonal test are analyzed by means of range analysis and variance analysis. The optimum combination of salt solution was determined as Na2SiO3O3NNaOHN1Na2SO4Ni2, also called 312 solution. 4) No matter how the age changed, the order of unconfined compressive strength from high to low was that of soaking and curing in solution of: 312. 鈫扴aturated Limestone soaking maintenance. 鈫扵he strength of the cement soil sample treated with standard curing. 312 solution immersion and saturated lime water immersion curing will tend to be gentle with the increase of age.) under standard curing condition, the elastoplastic deformation of cement soil will decrease with the increase of curing age. Embrittlement is becoming more and more obvious. Soaking and curing in solution can increase the elastoplastic deformation and plasticity of cement-soil, but with the increase of age, the increase will tend to be gentle, and saturated lime water soaking and curing can not increase the elastic-plastic deformation of cement-soil. But it can keep the plasticity of cement soil unchanged.
【學位授予單位】：西北農林科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU43

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