發(fā)布時間：2018-09-07 09:54

【摘要】：樁基礎(chǔ)是應(yīng)用最廣泛的基礎(chǔ)形式之一,其種類和形式多樣,主要功能為承受上部荷載并將豎向荷載傳遞至深層地基,因此極限豎向承載力的研究是樁基礎(chǔ)設(shè)計計算最為核心的內(nèi)容之一。目前,現(xiàn)行各規(guī)范均認為基樁側(cè)摩阻力與樁端阻力是相互獨立、互不聯(lián)系的兩個部分,即基樁極限承載力為側(cè)阻力與端阻力之和。然而從一些現(xiàn)場試驗資料及室內(nèi)模型試驗可發(fā)現(xiàn):樁側(cè)摩阻力與樁端阻力并非完全獨立,二者在樁基加載過程中存在某種程度的相互作用,且這種相互作用將使側(cè)阻值明顯增強,進而對基樁豎向承載力計算有較大影響。因此本文試圖對側(cè)阻增強效應(yīng)開展室內(nèi)模擬實驗,借助基樁靜載試驗觀測側(cè)阻增強效應(yīng)對基樁側(cè)摩阻力的影響,并探究樁徑對這一效應(yīng)的作用規(guī)律,在此基礎(chǔ)上引進極限分析法,模擬樁基承載過程中樁端阻力與樁側(cè)阻力的相互作用,提出可考慮基樁側(cè)阻增強效應(yīng)的極限樁基礎(chǔ)豎向承載力計算公式,對優(yōu)化基樁設(shè)計、進一步挖掘樁基承載潛能起到一定借鑒作用。本文首先根據(jù)室內(nèi)模型試驗,在基樁加載過程中對基樁端部一定范圍內(nèi)側(cè)阻變化規(guī)律進行監(jiān)測,驗證側(cè)阻增強效應(yīng)的存在,并基于不同樁徑的對比試驗,探討了樁徑對基樁側(cè)阻增強效應(yīng)的影響,結(jié)果表明隨樁徑增大,側(cè)阻增強效應(yīng)越明顯。然后在室內(nèi)模擬實驗研究的基礎(chǔ)上,考慮基樁底部樁土的相對位移量、樁土接觸面的性質(zhì)、樁端持力層的強度、樁端阻的發(fā)揮程度、土體復(fù)雜性等因素的影響,對基樁側(cè)阻增強效應(yīng)及過程進行模擬,并基于-深基礎(chǔ)破壞模式,引進極限分析上限法,推算出考慮側(cè)阻增強效應(yīng)的基樁豎向承載力公式,并對基樁豎向承載力的各影響因素進行敏感性分析,探求其各因素對側(cè)阻增強效應(yīng)的影響規(guī)律。最后引用現(xiàn)場基樁靜載實例數(shù)據(jù),基于本文改進的基樁豎向極限承載力公式,求得基樁豎向極限承載力值,并與傳統(tǒng)方法進行對比,驗證了本文公式的合理性。
[Abstract]:Pile foundation is one of the most widely used foundation forms. Its main function is to bear the upper load and transfer the vertical load to the deep foundation. Therefore, the study of ultimate vertical bearing capacity is one of the most important contents in the design and calculation of pile foundation. The ultimate bearing capacity of pile is the sum of lateral resistance and end resistance. However, some field test data and laboratory model tests show that the pile side friction and end resistance are not completely independent, and there is a certain degree of interaction between the two in the process of pile loading, and this interaction. Therefore, this paper attempts to carry out laboratory simulation experiments on the effect of lateral resistance enhancement, to observe the effect of lateral resistance enhancement on the side friction of foundation piles by means of static load test of foundation piles, and to explore the law of the effect of pile diameter on this effect, and on this basis, to introduce the limit score. Analytical method is used to simulate the interaction between pile tip resistance and pile side resistance in the process of pile bearing, and a formula for calculating the ultimate vertical bearing capacity of pile foundation considering the enhancement effect of pile side resistance is proposed, which can be used for reference in optimizing pile design and further excavating the bearing potential of pile foundation. In the course of construction, the variation law of side resistance at the end of pile is monitored to verify the existence of side resistance enhancement effect. Based on the comparative test of different pile diameters, the influence of pile diameters on the side resistance enhancement effect is discussed. The results show that the side resistance enhancement effect becomes more obvious with the increase of pile diameters. The relative displacement of pile and soil at the bottom of pile, the nature of pile-soil interface, the strength of bearing layer at the end of pile, the exertion degree of pile resistance, and the complexity of soil are the factors that influence the lateral resistance enhancement. Based on the failure mode of deep foundation, the upper limit method of limit analysis is introduced to calculate the pile considering the lateral resistance enhancement effect. The formulas of vertical bearing capacity are given, and the sensitivity of each influencing factor of vertical bearing capacity of foundation pile is analyzed, and the influence law of each influencing factor on lateral resistance enhancement effect is explored. The rationality of the formula is verified by comparison.
【學位授予單位】：湖南大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU473.1

【引證文獻】

相關(guān)碩士學位論文 前1條

1 郭潔;黃土地區(qū)CFG樁復(fù)合地基的極限承載性狀研究[D];西安科技大學;2017年

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本文編號：2227916