【摘要】：樁基礎(chǔ)作為一種重要的深基礎(chǔ)形式,具有沉降量小和承載力高的優(yōu)點,目前在大厚度黃土地區(qū)得到非常廣泛的應(yīng)用。工程實踐證明樁的側(cè)摩阻力在不同工況下取值會有很大的差異,為能深入研究樁與土體之間的相互作用,把握側(cè)摩阻力取值的規(guī)律,本文通過現(xiàn)場試驗、縮尺模型試驗和數(shù)值模擬分析相結(jié)合的方法進行研究,對考慮濕陷的大厚度黃土地區(qū)樁基負(fù)摩阻力特性有了更全面和深入的認(rèn)識,主要完成的工作和取得的成果如下： (1)借助實際工程,通過現(xiàn)場大型試驗研究樁基在天然狀態(tài)下及浸水條件下樁頂荷載與樁體沉降的關(guān)系；通過對黃土地區(qū)土體濕陷、沉降特點及不同深度土層的沉降變化特征的研究,分析了樁周土體沉降與樁身荷載傳遞規(guī)律之間的關(guān)系；分析了試樁在預(yù)浸水條件下樁身承載力和正負(fù)摩阻力的變化規(guī)律,并與未進行預(yù)浸水的試樁進行了對比分析,研究了樁身軸力分布和中性點位置變化以及樁身摩阻力的分布規(guī)律。 (2)以相似理論為基礎(chǔ),通過對國內(nèi)外樁基負(fù)摩阻力的試驗方案分析與研究,將原型樁和縮尺模型樁進行相似關(guān)系轉(zhuǎn)化,自主設(shè)計了一套考慮濕陷的樁基負(fù)摩阻力的縮尺模型試驗方案及方法,對大直徑沉管灌注單樁承載力進行縮尺模型試驗研究,并進行了負(fù)摩阻力試驗,得到了樁的中性點位置以及負(fù)摩阻力產(chǎn)生和發(fā)展的規(guī)律。 (3)基于ADINA大型有限元分析軟件對黃土地區(qū)單樁和群樁的負(fù)摩阻力進行了分析。主要研究內(nèi)容包括：有限元模型的建立、浸水計算模型的設(shè)置、樁基P-S關(guān)系分析、樁頂加載工況下樁身軸力分析、浸水工況下樁周土體沉降分析、浸水工況下樁身軸力分析和浸水工況下樁側(cè)負(fù)摩阻力分析。 (4)以西北黃土地區(qū)實際工程為背景,借助數(shù)值分析軟件ADINA,建立了有限元分析模型,計算了樁頂加載及浸水工況下,樁身軸力及負(fù)摩阻力,并對影響樁身軸力及負(fù)摩阻力特性的參數(shù)進行了分析。主要研究了黃土彈性模量、黃土粘聚力、樁頂荷載、樁體剛度和浸水壓力等對樁身軸力及負(fù)摩阻力的影響。
[Abstract]:As an important form of deep foundation, pile foundation has the advantages of small settlement and high bearing capacity, and is widely used in loess regions with large thickness. Engineering practice has proved that the value of side friction of pile will be very different under different working conditions. In order to study the interaction between pile and soil and grasp the law of side friction, this paper passes the field test. The method of scale model test and numerical simulation is used to study the characteristics of negative friction resistance of pile foundation in loess region with large thickness considering collapsibility. The main works and achievements are as follows: (1) with the aid of practical engineering, the relationship between pile top load and pile settlement under natural condition and flooding condition is studied by large-scale field test; The relationship between the settlement of soil around piles and the law of load transfer of piles is analyzed by studying the characteristics of soil subsidence and settlement in loess area and the characteristics of settlement of soil layers at different depths. The variation law of bearing capacity and positive and negative frictional resistance of test pile under pre-immersion condition is analyzed and compared with that of test pile without pre-immersion. The distribution of axial force and neutral point and the distribution of frictional resistance of pile body are studied. (2) based on the similarity theory, the negative friction of pile foundation at home and abroad is analyzed and studied. By transforming the similarity between the prototype pile and the scale model pile, a scale model test scheme and method considering the negative frictional resistance of the collapsing pile foundation are designed, and the bearing capacity of the large diameter sinking pipe cast-in-place single pile is studied by the scale model test. The negative frictional resistance test is carried out, and the neutral position of pile and the rule of the generation and development of negative friction resistance are obtained. (3) the negative friction resistance of single pile and pile group in loess area is analyzed based on ADINA large-scale finite element analysis software. The main research contents include: the establishment of finite element model, the setting of soaking calculation model, the analysis of P-S relation of pile foundation, the analysis of axial force of pile body under pile top loading, and the settlement analysis of soil around pile under flooding condition. The axial force analysis of pile body under flooding condition and the negative friction analysis of pile side under flooding condition. (4) based on the actual engineering in Northwest Loess region, the finite element analysis model is established with the aid of the numerical analysis software ADINA. The axial force and negative frictional resistance of the pile are calculated under the loading and flooding conditions of the pile top, and the parameters affecting the axial force and the negative friction resistance of the pile are analyzed. The effects of elastic modulus of loess, cohesive force of loess, load on pile top, stiffness of pile body and immersion pressure on axial force and negative friction of pile body are studied.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TU473.1;TU444

【參考文獻】

相關(guān)期刊論文 前10條

1 袁燈平,黃宏偉,馬金榮;軟土地基樁側(cè)負(fù)摩阻力三維非線性數(shù)值分析[J];地下空間;2004年04期

2 童建國;朱瑞燕;;固結(jié)軟土中單樁負(fù)摩擦離心機模型試驗研究[J];電力勘測設(shè)計;2006年01期

3 夏力農(nóng);王星華;蔣春平;;樁頂荷載對樁基負(fù)摩阻力特性的影響[J];防災(zāi)減災(zāi)工程學(xué)報;2005年04期

4 何頤華,閔連太;濕陷性黃土地基樁的負(fù)摩擦力問題[J];建筑結(jié)構(gòu)學(xué)報;1982年06期

5 陳福全,龔曉南,馬時冬;樁的負(fù)摩阻力現(xiàn)場試驗及三維有限元分析[J];建筑結(jié)構(gòu)學(xué)報;2000年03期

6 汪鵬程,楊俊杰,朱向榮;用有限元法探討凍結(jié)井井壁上融沉負(fù)摩擦力性狀[J];礦冶工程;2003年05期

7 袁燈平,黃宏偉,馬金榮;軟土地基樁側(cè)表面負(fù)摩阻力解析模型[J];上海交通大學(xué)學(xué)報;2005年05期

8 馬遠剛,童梅;樁側(cè)負(fù)摩阻力有限元模擬[J];水利水電快報;2004年24期

9 陸明生;樁基表面負(fù)摩擦力的試驗研究及經(jīng)驗公式[J];水運工程;1997年05期

10 聶如松,冷伍明;軟土地基橋臺樁基負(fù)摩擦力的試驗研究[J];鐵道建筑;2005年06期

，

本文編號：2189049