【摘要】：隨著我國經(jīng)濟(jì)建設(shè)的迅猛發(fā)展，為適應(yīng)經(jīng)濟(jì)發(fā)展的需要，有些工程不得不興建于軟土地基之上。我國軟土分布較為廣泛，以沿海地區(qū)居多。軟土的成因復(fù)雜，含水率高，天然孔隙比大，力學(xué)性質(zhì)較差，具有顯著的流變特性。軟土的流變性會(huì)造成工后沉降隨時(shí)間不斷增長(zhǎng)，導(dǎo)致各種工程發(fā)生損壞或失去使用功能。特別是對(duì)于一些公路，鐵路以及地下工程，軟土流變?cè)斐傻奈：陀葹轱@著。軟土的流變是與工程安全與正常使用息息相關(guān)的重要問題，，也是值得巖土工作者進(jìn)行深入研究的一個(gè)課題。 本文主要研究軟土的蠕變過程，基于兩種取自不同地區(qū)的軟土（天津和蘇州），以室內(nèi)試驗(yàn)為主要方法，結(jié)合土質(zhì)學(xué)，土力學(xué)與工程巖土學(xué)，對(duì)兩種軟土進(jìn)行了一系列基本物理力學(xué)試驗(yàn)，對(duì)比研究了兩種軟土工程特性。開展了一維固結(jié)蠕變?cè)囼?yàn)和直接剪切蠕變?cè)囼?yàn)，對(duì)比研究了兩種軟土的蠕變特性，并且根據(jù)一維固結(jié)蠕變?cè)囼?yàn)結(jié)果建立了兩種軟土蠕變的經(jīng)驗(yàn)?zāi)Ｐ�，根�?jù)直接剪切蠕變?cè)囼?yàn)建立了兩種軟土應(yīng)力應(yīng)變的半經(jīng)驗(yàn)修正理論模型。最后根據(jù)直接剪切試驗(yàn)的結(jié)果，建立了兩種軟土長(zhǎng)期強(qiáng)度的計(jì)算模型。 通過對(duì)兩種不同地區(qū)軟土物理力學(xué)性質(zhì)的測(cè)試發(fā)現(xiàn)，天津軟土與蘇州軟土比較，其軟土的典型性更強(qiáng)，其力學(xué)性質(zhì)更差。兩種軟土的粘滯系數(shù)隨著剪應(yīng)力的增大會(huì)呈現(xiàn)出先增大再減小的趨勢(shì)。針對(duì)兩種軟土不同的力學(xué)性狀，天津軟土其線性粘彈性部分采用標(biāo)準(zhǔn)線性體模型，線性粘塑性部分采用四元件的村山朔朗模型；蘇州軟土其線性粘彈性部分采用5參數(shù)的廣義Kelvin模型，線性粘塑性部分采用V/K—H體模型，非線性粘塑性部分均采用形式為Aln B的經(jīng)驗(yàn)公式來描述，這樣所建立的本構(gòu)模型經(jīng)過初步的驗(yàn)證是合理而適用的。根據(jù)直接剪切蠕變曲線上的拐點(diǎn)來確定長(zhǎng)期強(qiáng)度，可以求得兩種軟土的長(zhǎng)期強(qiáng)度指標(biāo)，天津軟土：c=7.3kPa，φ=6.27°，蘇州軟土：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 擄, Suzhou soft soil: 10. 1 KPA, 蠁 ~ (9.9) 擄.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU447;TU411

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