本文關(guān)鍵詞：大厚度自重濕陷性黃土場(chǎng)地樁基負(fù)摩阻力試驗(yàn)研究　出處：《蘭州理工大學(xué)》2013年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 濕陷性黃土 樁基浸水試驗(yàn) 預(yù)浸水作用 負(fù)摩阻力 分層沉降

【摘要】：在我國(guó)西北地區(qū),存在著大面積的自重濕陷性黃土,如何避免由于黃土濕陷性產(chǎn)生的負(fù)摩阻力給樁基工程帶來(lái)的巨大危害,已經(jīng)成為人們關(guān)注的重點(diǎn)問(wèn)題。然而現(xiàn)有的許多理論研究,尤其是樁—土相互作用理論研究的不完整性己不能完全滿足日益發(fā)展的工程建設(shè)的需要。因此對(duì)樁基進(jìn)行現(xiàn)場(chǎng)原位試驗(yàn)依然是研究其屬性的行之有效的根本方法,對(duì)完善其設(shè)計(jì)理論,指導(dǎo)工程實(shí)踐都有著十分重要的意義。 本文結(jié)合中國(guó)移動(dòng)集團(tuán)甘肅定西分公司綜合樓項(xiàng)目,在大厚度自重濕陷性黃土場(chǎng)地上進(jìn)行了長(zhǎng)時(shí)間的樁基浸水載荷試驗(yàn),設(shè)置試驗(yàn)樁三根,試驗(yàn)樁直徑800mm,樁長(zhǎng)分別為26m、29m、31.5m,注水試坑深度2m。其中試樁-1和試樁-2進(jìn)行承載力和負(fù)摩阻力測(cè)試,試樁-3只進(jìn)行承載力測(cè)試,并在試樁-1和試樁-2樁身埋設(shè)了大量的鋼筋應(yīng)變計(jì)和混凝土應(yīng)變計(jì),并在樁周45度對(duì)角線埋設(shè)了兩組分層沉降計(jì)用以觀測(cè)土體沉降情況。試驗(yàn)對(duì)不同深度下、不同范圍內(nèi)的樁側(cè)負(fù)摩阻力的變化特征以及土體的沉降過(guò)程進(jìn)行了分析�，F(xiàn)將實(shí)驗(yàn)結(jié)果及分析總結(jié)如下： (1)在本文所指出的特殊浸水條件下,樁側(cè)正、負(fù)摩阻力的變化以及土體沉降變化均呈現(xiàn)出多峰值狀態(tài),即沿樁身長(zhǎng)度向下,正、負(fù)摩阻力的分布出現(xiàn)交錯(cuò)分布狀態(tài),即不再是由一個(gè)中性點(diǎn)將正負(fù)摩阻力分開(kāi),而是出現(xiàn)了多個(gè)中性點(diǎn)；樁周土體沉降量亦沿樁身出現(xiàn)多個(gè)峰值,并且其變化趨勢(shì)直接影響樁側(cè)正、負(fù)摩阻力沿樁身交替變化的走勢(shì)；黃土的實(shí)際濕陷情況是分段發(fā)生濕陷的,而不是如傳統(tǒng)觀點(diǎn)所述在單一中性點(diǎn)以上突然出現(xiàn)整段濕陷。 (2)當(dāng)考慮預(yù)浸水作用時(shí),即兩樁在相互影響作用下得出了以下結(jié)論： 單樁豎向承載力試驗(yàn)得出的試樁-2承載力較試樁-1有明顯的降低,降低幅度大約為20%左右；試樁-2在預(yù)浸水后再加載,其正摩阻力呈現(xiàn)出隨荷載增大而增大的現(xiàn)象,而負(fù)摩阻力則是隨樁頂荷載的增大而增大。樁端阻力由于預(yù)浸水的作用,使得試樁-2相較試樁-1基本未發(fā)揮,維持在10kN左右,可忽略不計(jì)；對(duì)于預(yù)浸水之后加載,再進(jìn)行大面積浸水試驗(yàn)后,試樁-2相較于試樁-1,樁側(cè)阻力沿樁身的正負(fù)分布區(qū)段呈相反的狀態(tài)；試樁-2在6.5m和約9.7m兩個(gè)位置處呈現(xiàn)出隨時(shí)間增長(zhǎng),中性點(diǎn)位置反而上升的規(guī)律。
[Abstract]:In Northwest China, there is a large area of self weight collapsible loess, how to avoid because of the huge damage of negative friction resistance of loess collapsibility has brought to pile foundation engineering, has become the focus of attention. However, many of the existing theories, especially the theory of the interaction of soil pile is not complete has not fully meet the growing needs of engineering construction. Therefore on the pile in-situ test is still fundamentally effective method to investigate its properties, to improve the design theory, there are ten important guiding significance in engineering practice.
According to China Mobile group Gansu Dingxi branch building, the pile foundation water load test for long time in thick loess soil, set the test pile three, pile diameter 800mm, pile length were 26m, 29m, 31.5m, 2M. and flooding test pit depth pile test -1 and test -2 pile bearing capacity and negative friction test, only -3 pile bearing capacity test, and the test of pile and -1 pile -2 pile buried large reinforced concrete strain gauge and strain gauge, and in a pile of 45 degree diagonal buried two groups of layered settlement meter for settlement observation. Test of different depth, the settlement process variation of pile side friction in different areas and soil are analyzed. The experimental results and analysis are summarized as follows:
(1) special submergerence pointed out in this paper, the pile side is changed, the negative friction and soil settlement variation showed multi peak state, namely downward along the pile length is, the distribution of negative friction resistance of staggered distribution, that is no longer separated by a neutral point and negative friction resistance but, there is more than one neutral point; pile of soil along the pile settlement also had many peaks, and their trends directly affect the pile side friction along the trend of positive and negative pile alternating loess collapsibility; actual situation is segmented has collapsibility, but not as the traditional view of the in a single neutral point above the whole collapse suddenly appeared.
(2) when the effect of pre immersion is considered, the following conclusions are drawn under the interaction of two piles.
Test the test result of pile -2 pile bearing capacity is -1 significantly reduced the single pile vertical bearing, reduce the amplitude is about 20%; pile -2 in pre immersion after loading, the positive friction presents with the load increases with the increase of the phenomenon, while the negative friction is increased with the top of the pile the load increases. The pile tip resistance due to pre soaking effect, the test pile -2 pile -1 compared to did not play, maintained at about 10kN is negligible; for pre immersion after loading, then a large area of water immersion test, test pile -2 compared with -1 pile, pile side resistance along the pile of positive and negative the distribution section showed the opposite state; pile -2 in 6.5m and 9.7M at two locations showed increased over time, but the rise of the neutral point position.

【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：TU473.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 黃澤珍;軟土地基上大面積堆載下橋梁樁基負(fù)摩阻力分析[J];公路交通技術(shù);2004年03期

2 高國(guó)瑞;黃土顯微結(jié)構(gòu)分類與濕陷性[J];中國(guó)科學(xué);1980年12期

3 楊運(yùn)來(lái);黃土濕陷機(jī)理的研究[J];中國(guó)科學(xué)(B輯 化學(xué) 生物學(xué) 農(nóng)學(xué) 醫(yī)學(xué) 地學(xué));1988年07期

4 謝耀峰,王云球;碼頭樁基負(fù)摩擦力的模型試驗(yàn)研究[J];建筑結(jié)構(gòu);2004年12期

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

6 閆兵;陳穎輝;楊坤華;;荷載傳遞函數(shù)在樁基分析中的應(yīng)用[J];山西建筑;2007年02期

7 陸明生;樁基表面負(fù)摩擦力的試驗(yàn)研究及經(jīng)驗(yàn)公式[J];水運(yùn)工程;1997年05期

8 楊明宇;有效應(yīng)力法計(jì)算樁基負(fù)摩阻力[J];土工基礎(chǔ);2004年06期

9 吳一偉，費(fèi)涵昌，林僑興，，張遠(yuǎn)芳;砂土液化對(duì)樁基工程的影響[J];同濟(jì)大學(xué)學(xué)報(bào)(自然科學(xué)版);1995年03期

10 關(guān)慶華;李振作;張立英;;濕陷性黃土地區(qū)單樁豎向承載力靜載荷浸水試驗(yàn)[J];西北水電;2010年05期

相關(guān)博士學(xué)位論文 前1條

1 張曉健;現(xiàn)澆混凝土薄壁管樁負(fù)摩阻力特性試驗(yàn)研究與分析[D];河海大學(xué);2006年

相關(guān)碩士學(xué)位論文 前3條

1 周萬(wàn)歡;堆載固結(jié)過(guò)程中單樁負(fù)摩擦力性狀研究[D];浙江大學(xué);2005年

2 李祖仁;自重濕陷性黃土場(chǎng)地樁基浸水荷載試驗(yàn)研究[D];長(zhǎng)安大學(xué);2009年

3 唐國(guó)藝;關(guān)中地區(qū)某自重濕陷性黃土場(chǎng)地樁基負(fù)摩阻力試驗(yàn)研究[D];長(zhǎng)安大學(xué);2007年

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