本文選題：石灰處治膨脹土　切入點：物理力學性質(zhì)　出處：《廣西大學》2015年碩士論文　論文類型：學位論文

【摘要】：為研究干濕循環(huán)效應對石灰處治膨脹土強度特性的影響規(guī)律,本文以經(jīng)石灰處治過后的南寧弱膨脹土為研究對象,通過一系列室內(nèi)物理力學性質(zhì)試驗獲取該膨脹土改性前后的物理力學性質(zhì)指標,對三軸試樣進行干濕循環(huán)試驗,最后借助GDS動三軸儀對處治土開展靜力三軸剪切以及振動三軸試驗,主要研究內(nèi)容如下：1.對摻灰比6%的石灰處治膨脹土開展一系列室內(nèi)物理力學土工試驗,試驗結果表明：石灰處治土相比原膨脹土,比重降低,液限降低,塑限升高,塑性指數(shù)明顯降低,最大干密度降低,最優(yōu)含水率升高,由改性前的低液限黏土變性為低液限粉土,土樣由高壓縮性土變成了中低壓縮性土,自由膨脹率、線縮率和脹縮總率等指標相較于處治之前有明顯的降低,抑制了原膨脹土的脹縮性,改性后的膨脹土已屬于非膨脹土范疇,抗剪強度指標也得到顯著提升。2.對完成養(yǎng)護的三軸剪切試樣進行干濕循環(huán)試驗,對干濕循環(huán)的破壞效應進行了分析,認為干濕循環(huán)效應引起土體反復脹縮,導致土體內(nèi)部裂隙的發(fā)育,降低了土顆粒間的連接程度,從而使處治土的結構性遭到破壞,且破壞程度隨干濕循環(huán)的次數(shù)增加而增大。3.對完成0～5次幅度干濕循環(huán)且養(yǎng)護好的試樣分組進行固結不排水三軸試驗,試驗表明干濕循環(huán)對處治土的影響宏觀上表現(xiàn)為抗剪強度的不斷衰減,第1次、第2次干濕循環(huán)后粘聚力衰減幅度較大,第3次循環(huán)后衰減幅度減小并趨于穩(wěn)定,而內(nèi)摩擦角僅在第1次干濕循環(huán)后有較大衰減,總體而言變化幅度相當小,對抗剪強度的影響很小。4.針對處治土的動變形特性,研究了0～5次干濕循環(huán)效應下的骨干曲線(σ～εd曲線)、動彈模量與動應變關系曲線(Ed～εd曲線、1/Ed～εd曲線)、阻尼比與動應變關系曲線(λ～εd曲線)的變化規(guī)律,研究了固結壓力、固結比、動荷載頻率等因素在干濕循環(huán)效應下對處治土骨干曲線、動彈性模量和阻尼比等的影響,得到了不同因素影響下的骨干曲線本構關系模型、動彈性模量衰減模型。根據(jù)等效線性模型(Hardin-Drnevich模型)提出的等效阻尼比公式,計算得到全應變范圍內(nèi)的阻尼比λ,根據(jù)試驗結果確定最大阻尼比λmax；根據(jù)該模型提出的雙曲線型動應力動應變關系,擬合計算得到最大動彈模量Edmax。
[Abstract]:In order to study the effect of dry-wet cycle effect on the strength characteristics of expansive soil treated with lime, the weak expansive soil in Nanning after treated with lime is taken as the research object in this paper. Through a series of indoor physical and mechanical property tests, the physical and mechanical properties of the expansive soil before and after modification were obtained, and the dry and wet cycling tests of triaxial specimens were carried out. Finally, the static triaxial shear and vibration triaxial tests were carried out on the treated soil by GDS dynamic triaxial test. The main research contents are as follows: 1. A series of indoor physical and mechanical geotechnical tests were carried out on the lime treated expansive soil with the ratio of 6% with lime. The test results show that compared with the original expansive soil, lime treated soil has lower specific gravity, lower liquid limit, higher plastic limit, lower plastic index, lower maximum dry density and higher optimum moisture content. From the low liquid limit clay to the low liquid limit silt before modification, the soil sample changed from high compressible soil to medium and low compressible soil. The free expansion ratio, linear shrinkage rate and total expansion rate were obviously decreased compared with those before treatment. The dilatancy and shrinkage of the original expansive soil are restrained, the modified expansive soil has already belonged to the category of non-expansive soil, and the shear strength index has also been significantly improved .2.The dry and wet cycle tests have been carried out on the triaxial shear specimens which have been cured. The failure effect of dry-wet cycle is analyzed. It is considered that the dry-wet cycle results in repeated expansion and contraction of soil mass, which leads to the development of internal cracks in soil, reduces the degree of connection between soil particles, and results in the destruction of soil structure. The degree of failure increases with the increase of dry-wet cycle times. The undrained triaxial tests are carried out on the samples which have completed 0 ~ 5 amplitude dry and wet cycles and have been cured. The experimental results show that the influence of dry and wet cycles on soil treatment shows the continuous attenuation of shear strength. The cohesive force decreases greatly after the first and second dry and wet cycles, and the attenuation amplitude decreases and tends to be stable after the third cycle. However, the angle of internal friction only attenuates after the first dry-wet cycle, and the variation range is quite small, and the influence of shear strength is very small. 4. According to the dynamic deformation characteristics of treated soil, In this paper, the variation law of the key curve (蟽 ~ 蔚 d curve, dynamic modulus of elasticity and dynamic strain curve) and the curve of damping ratio and dynamic strain (位 ~ 蔚 d curve) under the dry and wet cycle of 0 ~ 0 ~ 5 times are studied, and the consolidation pressure and consolidation ratio are also studied. The influence of dynamic load frequency and other factors on soil backbone curve, dynamic elastic modulus and damping ratio under dry-wet cycle effect is studied, and the constitutive relation model of backbone curve under different factors is obtained. According to the equivalent linear model (Hardin-Drnevich model), the equivalent damping ratio formula is presented. The damping ratio 位 in the range of total strain is calculated, and the maximum damping ratio 位 maxis determined according to the experimental results. According to the hyperbolic dynamic stress-strain relation proposed by the model, the maximum dynamic modulus Edmaxis obtained by fitting.
【學位授予單位】：廣西大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU411;TU443

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