两种软土非线性蠕变特性与长期强度试验研究
发布时间：2018-09-10 20:28
【摘要】：随着我国经济建设的迅猛发展，为适应经济发展的需要，有些工程不得不兴建于软土地基之上。我国软土分布较为广泛，以沿海地区居多。软土的成因复杂，含水率高，天然孔隙比大，力学性质较差，具有显著的流变特性。软土的流变性会造成工后沉降随时间不断增长，导致各种工程发生损坏或失去使用功能。特别是对于一些公路，铁路以及地下工程，软土流变造成的危害就尤为显著。软土的流变是与工程安全与正常使用息息相关的重要问题，，也是值得岩土工作者进行深入研究的一个课题。 本文主要研究软土的蠕变过程，基于两种取自不同地区的软土（天津和苏州），以室内试验为主要方法，结合土质学，土力学与工程岩土学，对两种软土进行了一系列基本物理力学试验，对比研究了两种软土工程特性。开展了一维固结蠕变试验和直接剪切蠕变试验，对比研究了两种软土的蠕变特性，并且根据一维固结蠕变试验结果建立了两种软土蠕变的经验模型，根据直接剪切蠕变试验建立了两种软土应力应变的半经验修正理论模型。最后根据直接剪切试验的结果，建立了两种软土长期强度的计算模型。 通过对两种不同地区软土物理力学性质的测试发现，天津软土与苏州软土比较，其软土的典型性更强，其力学性质更差。两种软土的粘滞系数随着剪应力的增大会呈现出先增大再减小的趋势。针对两种软土不同的力学性状，天津软土其线性粘弹性部分采用标准线性体模型，线性粘塑性部分采用四元件的村山朔朗模型；苏州软土其线性粘弹性部分采用5参数的广义Kelvin模型，线性粘塑性部分采用V/K—H体模型，非线性粘塑性部分均采用形式为Aln B的经验公式来描述，这样所建立的本构模型经过初步的验证是合理而适用的。根据直接剪切蠕变曲线上的拐点来确定长期强度，可以求得两种软土的长期强度指标，天津软土：c=7.3kPa，φ=6.27°，苏州软土：c=10.1kPa，φ=9.9°。
[Abstract]:With the rapid development of economic construction in China, some projects have to be built on soft soil foundation to meet the needs of economic development. Soft soil is widely distributed in China, mostly in coastal areas. The soft soil has complex origin, high moisture content, large natural void ratio and poor mechanical properties, and has remarkable rheological properties. The rheological behavior of soft soil will cause post-construction settlement to increase with time, resulting in damage or loss of function of various projects. Especially for some highways, railways and underground projects, the damage caused by soft soil rheology is particularly significant. The rheology of soft soil is an important problem closely related to engineering safety and normal use. It is also a subject worthy of further study by geotechnical workers. In this paper, the creep process of soft soil is studied. Based on two kinds of soft soil from different areas (Tianjin and Suzhou), the main methods of laboratory test are combined with soil geology, soil mechanics and engineering geotechnology. A series of basic physical and mechanical tests were carried out on two kinds of soft soil, and the engineering characteristics of two kinds of soft soil were compared and studied. One-dimensional consolidation creep test and direct shear creep test are carried out. The creep characteristics of two kinds of soft soil are compared and studied. Based on the results of one-dimensional consolidation creep test, two kinds of creep experience models of soft soil are established. Based on the direct shear creep test, two semi-empirical modified models of stress and strain of soft soil are established. Finally, based on the results of direct shear test, two kinds of long-term strength calculation models of soft soil are established. By testing the physical and mechanical properties of soft soil in two different areas, it is found that compared with Suzhou soft soil, Tianjin soft soil has stronger typicality and worse mechanical properties. The viscosity coefficient of the two soft soils increases first and then decreases with the increase of shear stress. According to the different mechanical properties of two kinds of soft soil, the linear viscoelastic part of Tianjin soft soil is based on standard linear body model, and the linear viscoplastic part of Tianjin soft soil is based on a four-element Murayama model. The linear viscoelastic part of Suzhou soft soil is described by the generalized Kelvin model with five parameters, the linear viscoplastic part with the V/K-H body model, and the nonlinear viscoplastic part with the empirical formula in the form of Aln B. The constitutive model is reasonable and applicable after preliminary verification. According to the inflexion point on the direct shear creep curve, the long-term strength of two kinds of soft soil can be determined. Two kinds of long-term strength indexes can be obtained: Tianjin soft soil: 7. 3 KPA, 蠁 6. 27 掳, Suzhou soft soil: 10. 1 KPA, 蠁 ~ (9.9) 掳.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU447;TU411
本文编号：2235525
[Abstract]:With the rapid development of economic construction in China, some projects have to be built on soft soil foundation to meet the needs of economic development. Soft soil is widely distributed in China, mostly in coastal areas. The soft soil has complex origin, high moisture content, large natural void ratio and poor mechanical properties, and has remarkable rheological properties. The rheological behavior of soft soil will cause post-construction settlement to increase with time, resulting in damage or loss of function of various projects. Especially for some highways, railways and underground projects, the damage caused by soft soil rheology is particularly significant. The rheology of soft soil is an important problem closely related to engineering safety and normal use. It is also a subject worthy of further study by geotechnical workers. In this paper, the creep process of soft soil is studied. Based on two kinds of soft soil from different areas (Tianjin and Suzhou), the main methods of laboratory test are combined with soil geology, soil mechanics and engineering geotechnology. A series of basic physical and mechanical tests were carried out on two kinds of soft soil, and the engineering characteristics of two kinds of soft soil were compared and studied. One-dimensional consolidation creep test and direct shear creep test are carried out. The creep characteristics of two kinds of soft soil are compared and studied. Based on the results of one-dimensional consolidation creep test, two kinds of creep experience models of soft soil are established. Based on the direct shear creep test, two semi-empirical modified models of stress and strain of soft soil are established. Finally, based on the results of direct shear test, two kinds of long-term strength calculation models of soft soil are established. By testing the physical and mechanical properties of soft soil in two different areas, it is found that compared with Suzhou soft soil, Tianjin soft soil has stronger typicality and worse mechanical properties. The viscosity coefficient of the two soft soils increases first and then decreases with the increase of shear stress. According to the different mechanical properties of two kinds of soft soil, the linear viscoelastic part of Tianjin soft soil is based on standard linear body model, and the linear viscoplastic part of Tianjin soft soil is based on a four-element Murayama model. The linear viscoelastic part of Suzhou soft soil is described by the generalized Kelvin model with five parameters, the linear viscoplastic part with the V/K-H body model, and the nonlinear viscoplastic part with the empirical formula in the form of Aln B. The constitutive model is reasonable and applicable after preliminary verification. According to the inflexion point on the direct shear creep curve, the long-term strength of two kinds of soft soil can be determined. Two kinds of long-term strength indexes can be obtained: Tianjin soft soil: 7. 3 KPA, 蠁 6. 27 掳, Suzhou soft soil: 10. 1 KPA, 蠁 ~ (9.9) 掳.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU447;TU411
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