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

【摘要】：為研究干濕循環(huán)效應(yīng)對(duì)石灰處治膨脹土強(qiáng)度特性的影響規(guī)律,本文以經(jīng)石灰處治過(guò)后的南寧弱膨脹土為研究對(duì)象,通過(guò)一系列室內(nèi)物理力學(xué)性質(zhì)試驗(yàn)獲取該膨脹土改性前后的物理力學(xué)性質(zhì)指標(biāo),對(duì)三軸試樣進(jìn)行干濕循環(huán)試驗(yàn),最后借助GDS動(dòng)三軸儀對(duì)處治土開(kāi)展靜力三軸剪切以及振動(dòng)三軸試驗(yàn),主要研究?jī)?nèi)容如下：1.對(duì)摻灰比6%的石灰處治膨脹土開(kāi)展一系列室內(nèi)物理力學(xué)土工試驗(yàn),試驗(yàn)結(jié)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(xiàn)縮率和脹縮總率等指標(biāo)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(qiáng)度指標(biāo)也得到顯著提升。2.對(duì)完成養(yǎng)護(hù)的三軸剪切試樣進(jìn)行干濕循環(huán)試驗(yàn),對(duì)干濕循環(huán)的破壞效應(yīng)進(jìn)行了分析,認(rèn)為干濕循環(huán)效應(yīng)引起土體反復(fù)脹縮,導(dǎo)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(jié)構(gòu)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(duì)完成0～5次幅度干濕循環(huán)且養(yǎng)護(hù)好的試樣分組進(jìn)行固結(jié)不排水三軸試驗(yàn),試驗(yàn)表明干濕循環(huán)對(duì)處治土的影響宏觀上表現(xiàn)為抗剪強(qiáng)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(dāng)小,對(duì)抗剪強(qiáng)度的影響很小。4.針對(duì)處治土的動(dòng)變形特性,研究了0～5次干濕循環(huán)效應(yīng)下的骨干曲線(xiàn)(σ～εd曲線(xiàn))、動(dòng)彈模量與動(dòng)應(yīng)變關(guān)系曲線(xiàn)(Ed～εd曲線(xiàn)、1/Ed～εd曲線(xiàn))、阻尼比與動(dòng)應(yīng)變關(guān)系曲線(xiàn)(λ～εd曲線(xiàn))的變化規(guī)律,研究了固結(jié)壓力、固結(jié)比、動(dòng)荷載頻率等因素在干濕循環(huán)效應(yīng)下對(duì)處治土骨干曲線(xiàn)、動(dòng)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(xiàn)本構(gòu)關(guān)系模型、動(dòng)彈性模量衰減模型。根據(jù)等效線(xiàn)性模型(Hardin-Drnevich模型)提出的等效阻尼比公式,計(jì)算得到全應(yīng)變范圍內(nèi)的阻尼比λ,根據(jù)試驗(yàn)結(jié)果確定最大阻尼比λmax；根據(jù)該模型提出的雙曲線(xiàn)型動(dòng)應(yīng)力動(dòng)應(yīng)變關(guān)系,擬合計(jì)算得到最大動(dòng)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(xué)位授予單位】：廣西大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TU411;TU443

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