本文關(guān)鍵詞：樁土界面特征對(duì)非擠土樁承載性狀的影響分析　出處：《鄭州大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 界面本構(gòu)模型 非擠土樁 修正荷載傳遞法 相對(duì)粗糙度 接觸面厚度樁側(cè)摩阻力

【摘要】：在高層建筑、橋梁、市政和港口等深基礎(chǔ)工程中，常用的、最為經(jīng)濟(jì)的樁型之一是非擠土樁，如鉆孔灌注樁。對(duì)于其他條件相同但成孔方式不同的鉆孔灌注樁，其承載能力往往差異較大。其根本原因在于因鉆孔方式不同導(dǎo)致樁土界面的接觸特征相差較大。樁土界面特征，本文是指樁土接觸界面的相對(duì)剛度、相對(duì)粗糙度、樁土接觸面附近土的變形特征、樁周接觸面附近土體剪切受荷后剪切帶的形成、發(fā)展及表現(xiàn)出的剪脹、剪縮特性，以及樁徑和土的初始應(yīng)力水平等。 本文主要針對(duì)砂土的剪切變形特征，尤其是處于臨界狀態(tài)時(shí)所表現(xiàn)出的剪脹或剪縮特性，在以往學(xué)者對(duì)土-結(jié)構(gòu)面接觸特性試驗(yàn)和本構(gòu)模型研究的基礎(chǔ)上，歸納、計(jì)算（應(yīng)用所編制的計(jì)算程序）和分析了土-結(jié)構(gòu)面接觸特性對(duì)剪切變形的影響規(guī)律，并與其他文獻(xiàn)的計(jì)算結(jié)果進(jìn)行比較，驗(yàn)證了數(shù)值方法的正確性。該接觸面剪切模型是一種薄層臨界狀態(tài)模型，薄層厚度即為剪切帶寬度。然后將該接觸面模型應(yīng)用到非擠土樁中。在對(duì)傳統(tǒng)的樁基承載計(jì)算的傳遞函數(shù)法進(jìn)行修正的基礎(chǔ)上，運(yùn)用所編制的樁基修正的傳遞函數(shù)法計(jì)算程序，分析了考慮樁土界面接觸特性對(duì)單樁承載性狀的影響，，揭示側(cè)摩阻力的發(fā)揮與樁土相對(duì)位移的關(guān)系。使得樁基的承載和沉降計(jì)算能夠考慮更多的實(shí)際因素，分析更接近于實(shí)際情況，從而使樁基承載性狀的研究更趨于合理。 主要研究成果如下： （1）本文采用的界面剪切模型雖然模型參數(shù)較多，但能夠很好地描述土-結(jié)構(gòu)界面的剪切特性，且能夠較好地用于樁基承載性能的研究。 （2）采用CNL和CNS兩種數(shù)值試驗(yàn)，分析影響土-結(jié)構(gòu)界面剪切特性的相關(guān)參數(shù)，得到：砂土的初始孔隙比越小、圍壓越小、接觸面厚度越薄、法向剛度越小，剪切時(shí)的剪脹性越明顯、剪縮性越弱、達(dá)到相變狀態(tài)需要的體應(yīng)變也越��；對(duì)于密砂而言，接觸面越相對(duì)粗糙，峰值剪應(yīng)力強(qiáng)度越大，應(yīng)變軟化現(xiàn)象越明顯，而對(duì)于相對(duì)光滑接觸面，砂土呈現(xiàn)的剪縮特性較強(qiáng)，其應(yīng)變軟化現(xiàn)象不明顯。 （3）樁土接觸面越相對(duì)粗糙、樁周土體越密實(shí)，單樁的豎向承載力越大，樁的側(cè)摩阻力沿深度分布所呈現(xiàn)的非線性越明顯且峰值越大，同時(shí)樁側(cè)摩阻力的發(fā)揮需要更大的樁土相對(duì)位移。 （4）樁周土體因接觸面相對(duì)粗糙度的不同，剪切時(shí)出現(xiàn)剪縮或先剪縮后剪脹現(xiàn)象，應(yīng)力應(yīng)變關(guān)系呈現(xiàn)出軟化或硬化特性。
[Abstract]:In high-rise buildings, bridges, ports and other municipal and commonly used in deep foundation engineering, pile type, one of the most economical non compaction pile, bored pile. As for the other conditions are the same but different hole bored pile, the bearing capacity is often quite different. The main reason for drilling different ways lead to the contact characteristics between the pile and the soil is larger. The characteristics of pile-soil interface, this paper refers to the soil pile interface relative stiffness, relative roughness, deformation characteristics of pile soil contact surface of the soil near the pile near the contact surface, week of shear loading after the formation of shear bands, and showed the development of shear dilatancy, shear contraction, and the diameter of the pile and the soil initial stress level.
In this paper, the sand shear deformation characteristics, especially in the critical state exhibit dilatancy or shear contraction, in previous studies on soil structure contact based characteristic test and constitutive model research, induction, calculation (program application compiled) and analysis of the soil structure surface contact characteristics influence of shear deformation, and the calculation results were compared with other literatures, to verify the correctness of the numerical method. The shear model is a thin layer of critical state model, the thickness of the thin is the width of the shear band. Then the contact model is applied to non compaction pile in pile foundation. The traditional calculation of load transfer function method is modified on the basis of using pile foundation compiled by modified method of transfer function calculation program, considering the contact characteristics of pile-soil interface effect on bearing capacity of single pile, revealing the side The relationship between frictional resistance and relative displacement of pile and soil makes the calculation and calculation of pile foundation bearing more practical factors. The analysis is more close to the actual situation, so that the study of pile bearing behavior is more reasonable.
The main research results are as follows:
(1) the interface shear model adopted in this paper has many model parameters, but it can well describe the shear properties of soil structure interface, and it can be applied to the research of pile foundation bearing capacity better.
(2) using CNL and CNS two kinds of numerical experiments, analysis the influence of the soil structure interface shear properties of the relevant parameters, are: the initial pore sand ratio is smaller, the smaller the pressure, the contact surface of the thin thickness, normal stiffness decreases, shear dilatancy and shear shrinkage is more obvious. The weaker to body strain phase transition also takes less; for dense sand, the contact surface is relatively rough, the peak shear stress intensity, strain softening phenomenon is more obvious, while the relatively smooth surface, strong sand presents shear contraction, the strain softening phenomenon is not obvious.
(3) the more rough the pile soil contact surface is, the more dense the soil around the pile is, and the larger the vertical bearing capacity of a single pile is. The larger the pile side friction is, the larger the larger the peak value is. The bigger the pile side friction is, the greater the relative displacement of pile and soil will be.
(4) due to the different roughness of the contact surface, shear stress or shear dilatation first appeared in the soil around the pile, and the relationship between stress and strain showed softening or hardening characteristics.

【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU473.1

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