生物酶改良膨胀土物理力学特性试验研究

发布时间：2018-08-02 11:51

【摘要】：膨胀土是一种特殊的粘性土,具有遇水膨胀、失水收缩的工程特征,对各类工程具有非常大的危害。因而在膨胀土地区修建公路,常常需要对膨胀土进行改良,现有研究大多数以在膨胀土中掺石灰、粉煤灰、水泥、风化砂、HEC固化剂、HTAB和STW型土壤稳定剂等为主,但是存在施工问题、污染环境、成本过高、操作困难等缺点。本文依托湖南省交通厅科技项目“极端气候下膨胀土路基水毁灾害影响预测研究”(编号:19801-8025)、2015年湖南省研究生科研创新项目(CX2015B308)和中南林业科技大学研究生科技创新基金(项目编号:CX2015B31)“生物酶改良膨胀土物理力学特性试验研究”,研究了生物酶掺量与膨胀土基本物理特性指标之间的变化规律,探讨了生物酶掺量与改良膨胀土应力——应变曲线以及强度特性之间的变化规律,得出了生物酶掺量与改良膨胀土压缩特性之间的变化规律。研究成果为利用生物酶改良膨胀土的物理性质、胀缩性质、强度性质提供科学依据,为今后膨胀土的处治提供一种高效、环保、经济、操作性强的新型技术。本文的主要研究内容与成果如下:1.通过生物酶改良膨胀土的基本物理特性试验,研究了生物酶改良膨胀土的液限、塑限、最佳含水率、最大干密度、膨胀土判别指标与生物酶掺量之间的变化规律,并与石灰改良膨胀土的液限、塑限、最佳含水率、最大干密度、膨胀土判别指标进行对比,得到了生物酶改良膨胀土物理特性优于石灰改良膨胀土的物理特性的结论。2.通过直接剪切试验、室内三轴压缩试验,研究了生物酶改良膨胀土的强度特性以及应力——应变之间关系,探讨了生物酶掺量对改良膨胀土剪切强度影响的变化规律,同时与石灰、水泥改良膨胀土进行对比,得出掺生物酶可以显著提高膨胀土的强度指标的结论。3.通过对常规三轴压缩试验数据进行处理,基于邓肯—张模型理论,分析了生物酶掺量对膨胀土体切线变形模量的影响规律,得出生物酶改良膨胀土体切线变形模量的最佳掺量。4.通过一维固结试验,探究固结压力对生物酶改良膨胀土体压缩特性的影响,得出不同掺量的生物酶改良膨胀土体孔隙比、压缩系数、单位沉降量与荷载变化规律,并与石灰、水泥改良膨胀土体孔隙比、压缩系数、单位沉降量与荷载变化规律进行对比。5.通过生物酶改良膨胀土的自由膨胀率试验、无荷膨胀率试验以及有荷膨胀率试验,研究了不同掺量的生物酶改良膨胀土膨胀特性的变化规律,同时与石灰、水泥改良膨胀土的自由膨胀率、无荷膨胀率以及有荷膨胀率进行对比,得出生物酶改良膨胀土膨胀特性优于掺石灰、水泥改良膨胀土的结论。
[Abstract]:Expansive soil is a kind of special clay soil, which has the engineering characteristics of water expansion and water loss shrinkage, which is very harmful to all kinds of projects. Therefore, it is often necessary to improve the expansive soil in the construction of highway in the expansive soil area. Most of the existing researches mainly include lime, fly ash, cement, weathered sand HEC curing agent, STW type soil stabilizer and so on. However, there are construction problems, environmental pollution, high cost, difficult operation and other shortcomings. This paper relies on the science and technology project of Hunan Provincial Communications Department, "Research on predicting the impact of Water damage disaster on expansive soil roadbed under extreme Climate" (No.: 19801-8025), the Graduate Scientific Research Innovation Project of Hunan Province (CX2015B308) in 2015 and the Scientific and technological Innovation of Graduate students of Central South University of Forestry Science and Technology The Foundation (Project No.: CX2015B31), "Experimental study on physical and Mechanical Properties of Enzymatic Enzymatic modified expansive soil," The variation law between the amount of biological enzyme and the basic physical properties of expansive soil is studied. The relationship between the content of biological enzyme and the stress-strain curve and the strength characteristic of the expansive soil is discussed. The relationship between the amount of enzyme and the compressibility of the improved expansive soil was obtained. The research results provide a scientific basis for improving the physical properties, dilatation properties and strength properties of expansive soils by using biological enzymes, and provide a new technology with high efficiency, environmental protection, economy and strong operability for the treatment of expansive soils in the future. The main contents and results of this paper are as follows: 1. Based on the experiment of the basic physical properties of the expansive soil modified by biological enzyme, the variation law of liquid limit, plastic limit, optimum moisture content, maximum dry density, discriminant index of expansive soil and the amount of biological enzyme were studied. Compared with the liquid limit, plastic limit, optimum moisture content, maximum dry density and the discriminant index of expansive soil, the conclusion that the physical properties of modified expansive soil with biological enzyme is better than that of lime modified expansive soil is obtained. Through direct shear test and triaxial compression test in laboratory, the strength characteristics and stress-strain relationship of modified expansive soil with biological enzyme were studied, and the variation law of the effect of enzyme content on the shear strength of improved expansive soil was discussed. At the same time, compared with lime and cement modified expansive soil, it is concluded that the strength index of expansive soil can be significantly improved by adding biological enzyme. By processing the data of conventional triaxial compression test and based on Duncan Chang model theory, the effect of enzyme content on tangent deformation modulus of expansive soil is analyzed, and the optimum content of biological enzyme to improve tangent deformation modulus of expansive soil is obtained. Through the one-dimensional consolidation test, the effect of consolidation pressure on the compression characteristics of expanded soil improved by biological enzyme was investigated. The porosity ratio, compression coefficient, unit settlement and load change of expanded soil were improved with different amount of biological enzyme, and the change law of unit settlement and load were obtained. The porosity ratio, compression coefficient, unit settlement of the expansive soil improved by cement are compared with the load variation law. 5. Through the experiments of free expansion rate, no charge expansion rate and load expansion rate of modified expansive soil with biological enzyme, the change law of expansion characteristics of the expansive soil modified by biological enzyme with different amounts was studied, and the change of the expansion characteristics of the expansive soil with different amount of enzyme was studied, at the same time, Compared with the free expansion rate, the no charge expansion rate and the load expansion rate of the cement modified expansive soil, it is concluded that the expansion characteristics of the biological enzyme modified expansive soil are better than that of the lime modified expansive soil and the cement modified expansive soil.
【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU443

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