纤维泡沫颗粒轻质土力学性质试验研究

发布时间：2019-02-25 08:32

【摘要】：泡沫颗粒轻质土是指由轻质材料EPS(Expanded Polystyrene)泡沫颗粒、固化剂和原料土等混合而成的一种轻质填土材料。该材料与一般土体相比具有密度小、直立性好、耐久、经济、环保等优点,具有广泛的应用前景。为改善轻质土性能,添加纤维,形成纤维泡沫颗粒轻质混合土(下文简称轻质土)。本文通过密度试验、无侧限抗压强度实验、直剪实验等室内力学实验,研究轻质土的密度特性、变形特性和强度特性等,为工程应用提供参考,具体研究内容如下:(1)通过密度试验得到不同配比轻质土的密度特性。EPS颗粒掺入比和EPS颗粒粒径是影响密度的主要因素,随着EPS颗粒掺入比和粒径增大,轻质土密度减小,水泥掺量和纤维长度对轻质土密度影响不明显。(2)不同配比轻质土的变形特性。通过无侧限抗压强度试验和直剪试验,分析了不同配比轻质土的应力应变规律和剪应力剪位移变化规律;对无侧限抗压强度应力应变曲线进行拟合,研究了无侧限抗压变形模量的变化规律,得到变形模量与抗压强度的关系。(3)无侧限抗压强度中,随着EPS颗粒掺入比和粒径增大,无侧限抗压强度减小;随着水泥掺量增大,无侧限抗压强度增大;随纤维长度增加,无侧限抗压强度呈现逐渐增大的趋势,轻质土的整体性增强。(4)直剪试验中,随着EPS掺入比和粒径增大,轻质土抗剪强度减小,粘聚力减小;随着水泥掺量增大,轻质土抗剪强度增大,粘聚力增大;纤维长度从9mm增加到12mm,抗剪强度增幅达到40%,说明纤维长度达12mm时能够显著提高轻质土抗剪强度。(5)轻质土无侧限压缩破坏形态:EPS粒径为0.5~1mm的轻质土形成约45°裂缝且呈脆性破坏,EPS粒径为2~3mm的轻质土形成大于45°裂缝,EPS粒径为3~5mm的轻质土出现鼓胀破坏。直剪破坏形态:试样破坏的剪切面较明显,EPS颗粒粒径较小的剪切面比较平整,而粒径较大的剪切面相对松散;纤维的添加,试样裂而不断,土体整体性提高。
[Abstract]:Foamed granular lightweight soil is a lightweight filling material composed of EPS (Expanded Polystyrene) foam particles, curing agent and raw soil. Compared with general soil, this material has the advantages of low density, good standing, durability, economy, environmental protection, and so on, so it has a wide application prospect. In order to improve the properties of lightweight soil, fiber was added to form fiber foam particle lightweight mixed soil (hereinafter referred to as lightweight soil). In this paper, the density, deformation and strength characteristics of light soil are studied by means of density test, unconfined compressive strength test, direct shear test and so on, which provide reference for engineering application. The specific research contents are as follows: (1) the density characteristics of lightweight soils with different ratios are obtained by density test. The EPS particle ratio and EPS particle size are the main factors affecting the density, and with the increase of EPS particle incorporation ratio and particle size, The density of light soil is decreased, and the influence of cement content and fiber length on the density of light soil is not obvious. (2) the deformation characteristics of light soil with different ratio. Through the unconfined compressive strength test and the direct shear test, the stress-strain law and shear stress shear displacement change law of light soil with different proportions are analyzed. By fitting the stress-strain curve of unconfined compressive strength, the variation of deformation modulus of unconfined compressive strength is studied, and the relationship between deformation modulus and compressive strength is obtained. (3) in unconfined compressive strength, The unconfined compressive strength decreases with the increase of the ratio and particle size of EPS particles. With the increase of cement content, the unconfined compressive strength increases. With the increase of fiber length, the unconfined compressive strength increases gradually, and the integrity of lightweight soil increases. (4) in the direct shear test, the shear strength and cohesion decrease with the increase of EPS ratio and particle size. With the increase of cement content, the shear strength and cohesion of lightweight soil increase. The length of the fiber increased from 9mm to 12 mm, and the shear strength increased by 40 mm. The results show that the shear strength of light soil can be improved significantly when the fiber length reaches to 12mm. (5) the unconfined compression failure mode of light soil: the light soil with EPS diameter of 0.5~1mm forms about 45 掳crack and presents brittle failure. The light soil with EPS diameter of 2~3mm formed more than 45 掳crack, and the light soil with EPS diameter of 3~5mm appeared bulging failure. Direct shear failure pattern: the shear surface of specimen is obvious, the shear plane with smaller EPS particle size is flat, and the shear plane with larger particle size is relatively loose; with the addition of fiber, the specimen is cracked and the whole soil is improved.
【学位授予单位】：湖北工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU41

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