【摘要】：GRF（Geo-Reinforement type Foundation）樁基礎(chǔ)是一種新型巖土增強型基礎(chǔ)，它在超大直徑樁周圍分層、輻射狀分布錨桿來改善樁-土相互作用機理。該種樁基礎(chǔ)具有施工工藝簡單、承載力大、沉降小、節(jié)約成本、經(jīng)濟效益和社會效益高等明顯優(yōu)點，特別適用于一樁一柱的大型基礎(chǔ)，具有廣闊的應(yīng)用前景。為了闡明GRF樁基礎(chǔ)在豎直荷載作用下的承載機理，本文利用巖土計算軟件FLAC3D，建立三維非線性模型，考慮樁-土、錨桿-土的接觸效應(yīng)，分析研究了樁側(cè)土體、錨桿及樁端土體變形機制，以及錨桿長度、錨桿數(shù)量、錨桿間距和錨桿排數(shù)對GRF樁基礎(chǔ)承載力和樁土變形特性的影響，取得了如下成果： 1GRF樁基礎(chǔ)具有承載力大、沉降小等特點，這是因為錨桿的存在使得GRF樁基礎(chǔ)表現(xiàn)出與普通等直徑直樁不同的承載特性，錨桿伸入土中，在上部豎直荷載作用下，隨樁體向下位移，受到土體對它的向上的反作用力，構(gòu)成樁體承載力的重要組成部分。 2隨著荷載的增大，錨桿作用發(fā)揮程度增加；錨桿發(fā)揮作用程度越大，GRF樁基礎(chǔ)樁側(cè)土體變形相對于等直徑直樁樁側(cè)土體變形越小，而且錨桿作用的發(fā)揮改變了GRF樁基礎(chǔ)樁側(cè)土體的受力變形特性。錨桿長度范圍內(nèi)的土體變形由原來的剪切變形轉(zhuǎn)化為剪切、壓縮組合變形。 3由于錨桿的存在，，GRF樁基礎(chǔ)樁周土體變形明顯小于等直徑直樁的樁周土體變形，且樁側(cè)土體變形表現(xiàn)出了不同的趨勢。錨桿受到下部土體的反作用力而發(fā)生變形，錨桿的變形隨著荷載的增大而增大，且在相同荷載作用下不同埋置深度錨桿變形也不同。 4計算結(jié)果表明，GRF樁基礎(chǔ)的承載力隨著錨桿長度的增加而增加，增加錨桿數(shù)量可使GRF樁基礎(chǔ)承載力明顯提高，在錨桿總數(shù)不變的情況下增加錨桿的排數(shù)或增大錨桿間距可使GRF樁基礎(chǔ)承載力得到一定程度的提高。
[Abstract]:GRF (Geo-Reinment type Foundation) pile foundation is a new type of geo-soil enhanced foundation, which delaminate around super-diameter piles and radially distributes anchors to improve the pile-soil interaction mechanism. This kind of pile foundation has the advantages of simple construction technology, large bearing capacity, small settlement, saving cost, high economic benefit and social benefit. It is especially suitable for large foundation with one pile and one column, and has broad application prospect. In order to elucidate the bearing mechanism of GRF pile foundation under vertical load, a three-dimensional nonlinear model is established by using the geotechnical calculation software FLAC3D. considering the pile-soil contact effect, the pile-side soil mass is analyzed and studied. The deformation mechanism of anchor and pile end soil, and the influence of length of anchor rod, number of anchors, spacing of anchor rod and number of anchor bars on bearing capacity and deformation characteristics of GRF pile foundation have been obtained as follows: (1) the bearing capacity of GRF pile foundation is large, the bearing capacity of GRF pile foundation is large, and the bearing capacity of GRF pile foundation is large. This is because the existence of anchor rod makes the foundation of GRF pile show different bearing characteristics from that of ordinary straight pile with equal diameter. The anchor rod extends into the soil and displacements with the pile body under the action of vertical load in the upper part. By the soil upward reaction force, constitute an important part of the bearing capacity of the pile. 2 with the increase of load, the role of anchor increased; The larger the acting degree of anchor is, the smaller the deformation of soil around GRF pile foundation is compared with that of equal diameter straight pile side soil, and the effect of anchor rod on the deformation characteristics of pile side soil of GRF pile foundation is changed. The deformation of soil in the range of anchor length is changed from original shear deformation to shear deformation and compression combined deformation. 3 because of the existence of anchor rod, the deformation of soil around the pile of GRF pile foundation is obviously smaller than that of the soil around the pile with equal diameter vertical pile. The deformation of the soil around the pile shows different trends. The anchor rod is deformed by the reaction force of the lower soil, and the deformation of the anchor rod increases with the increase of the load. The calculated results show that the bearing capacity of GRF pile foundation increases with the increase of anchor length, and the bearing capacity of GRF pile foundation can be obviously increased by increasing the number of anchors. The bearing capacity of GRF pile foundation can be improved to a certain extent by increasing the number of anchors or increasing the spacing of anchors when the total number of anchors is constant.
【學(xué)位授予單位】：長江科學(xué)院
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：TU473.1

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