两种改性水泥土的制备与力学性能研究

发布时间：2018-03-28 10:33

本文选题：水泥土　切入点：二次纤维　出处：《中国矿业大学》2015年硕士论文

【摘要】：近年来,随着我国经济建设迅速发展,基础设施建设的规模越来越大。很多工程不得不在软土地基上进行建设,由于软土物理力学性质较差,因此需对软土地基进行人工加固。水泥土用于处理软土地基取得了良好的效果,且由于其经济、环保和易于施工,现已广泛应用于房建、水利和交通等各类工程领域。然而也因早期强度低、后期变形大和韧性差等缺点而受到限制。本文本着发展“绿色”建材的宗旨,结合水泥土及其他水泥基材料的改性措施,利用二次纤维和微生物对水泥土的力学性能进行改善。首先通过两种改性水泥土的无侧限抗压强度试验,对应力-应变曲线、强度、模量及韧性进行了研究,分析了二次纤维或微生物和龄期对水泥土力学性能的影响。其次,通过微观结构试验,如扫描电子显微镜试验和压汞实验,分析二次纤维或微生物改善水泥土力学性能的机理。再次,利用分离式霍普金森压杆试验装置进行两种改性水泥土的冲击压缩试验,并对比分析两种改性水泥土的静态、动态力学性能。然后,在损伤力学理论基础上,为两种改性水泥土选择合适的损伤变量,并通过循环加-卸载试验揭示了两种改性水泥土的损伤演化规律。最后,根据微生物增强水泥土的室内试验结果,分别对复合地基的承载力特征值和加固区沉降量进行计算。室内试验结果表明:二次纤维可以有效增大水泥土的韧性;水泥土的强度、弹性模量和韧性随着菌液浓度的增大而增大。与无侧限抗压强度试验结果相比,在冲击荷载下,两种改性水泥土的强度和弹性模量增大,韧性减小。微生物增强水泥土在复合地基中的应用设计表明:随着菌液浓度的增大,复合地基承载力特征值增大、加固区沉降量减小。
[Abstract]:In recent years, with the rapid development of economic construction in China, the scale of infrastructure construction is becoming larger and larger. Many projects have to be built on soft soil foundation, because of the poor physical and mechanical properties of soft soil. Therefore, it is necessary to strengthen the soft ground manually. The cement soil is used to treat the soft foundation with good results, and because of its economy, environmental protection and easy construction, it has been widely used in housing construction. Water conservancy and transportation are all kinds of engineering fields. However, they are also limited by the shortcomings of low early strength, large deformation and poor toughness in the later stage. This paper, in line with the purpose of developing "green" building materials, combines the modification measures of cement, soil and other cement-based materials. The mechanical properties of cement-soil were improved by secondary fiber and microorganism. Firstly, the stress-strain curve, strength, modulus and toughness of two kinds of modified cement-soil were studied by unconfined compressive strength test. The influence of secondary fiber or microorganism and age on the mechanical properties of cement soil was analyzed. Secondly, the microstructure test, such as scanning electron microscope (SEM) and mercury injection test, was used to analyze the effect of secondary fiber or microorganism and age on the mechanical properties of cement soil. The mechanism of improving the mechanical properties of cement soil by secondary fiber or microorganism is analyzed. Thirdly, the impact compression test of two kinds of modified cement soil is carried out by using separate Hopkinson pressure bar test device, and the static state of two kinds of modified cement soil is compared and analyzed. Dynamic mechanical properties. Then, on the basis of damage mechanics theory, the appropriate damage variables are selected for two kinds of modified cement-soil, and the damage evolution laws of two kinds of modified cement-soil are revealed by cyclic load-unloading test. According to the laboratory test results of microorganism reinforced cement soil, the bearing capacity characteristic value of composite foundation and the settlement of strengthened area are calculated respectively. The results of laboratory test show that the secondary fiber can effectively increase the toughness of cement soil, the strength of cement soil, the strength of cement soil, the strength of cement soil, the strength of cement soil and the strength of cement soil. The elastic modulus and toughness increase with the increase of the bacterial solution concentration. Compared with the unconfined compressive strength test results, the strength and elastic modulus of the two modified cement soils increase under impact load. The application design of microorganism reinforced cement soil in composite foundation shows that with the increase of bacterial concentration, the characteristic value of bearing capacity of composite foundation increases and the settlement of strengthened area decreases.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU43

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