本文選題：嵌巖樁 + 極限承載力�。� 參考：《蘭州交通大學(xué)》2017年碩士論文

【摘要】：嵌巖樁基已被廣泛應(yīng)用在高層建筑、橋梁等大型工程中。但由于樁周土體、巖體特性的多樣性和樁土、樁巖相互作用的復(fù)雜性以及試樁試驗耗時耗力、所需費(fèi)用高、所得數(shù)據(jù)存在較大的離散性等問題存在,導(dǎo)致樁基現(xiàn)場原位試驗很難達(dá)到精準(zhǔn)的結(jié)果。故國內(nèi)現(xiàn)行規(guī)范關(guān)于嵌巖樁極限承載力的研究主要利用半理論半經(jīng)驗的公式來計算。依據(jù)這一現(xiàn)狀,對嵌巖樁的極限承載力進(jìn)行更深入、更徹底的研究已顯得十分必要。本文通過收集、整理180根試樁資料,從中選出典型的38根試樁(30根軟巖嵌巖樁和8根硬巖嵌巖樁)作為本文考慮長徑比和嵌巖比等因素來推導(dǎo)嵌巖樁極限承載力修正計算公式的依據(jù)。通過38根試樁的現(xiàn)場原位測試數(shù)據(jù)分析計算與有限元數(shù)值模擬進(jìn)行對比研究,推導(dǎo)出考慮長徑比和嵌巖比對嵌巖樁極限承載力影響的修正計算公式,本文完成的主要內(nèi)容如下:(1)通過認(rèn)真學(xué)習(xí)國內(nèi)外嵌巖樁的試驗研究和文獻(xiàn)資料,歸納總結(jié)嵌巖樁的承載機(jī)理和荷載傳遞特性。對嵌巖樁豎向承載力特性及嵌巖樁樁土側(cè)阻力、樁巖側(cè)阻力以及樁端阻力的發(fā)揮特性進(jìn)行分析,討論了影響嵌巖樁豎向極限承載力的主要因素:嵌巖樁上部樁周土層性質(zhì)、下部樁周巖石層性質(zhì)、樁與樁周土的相對位移、樁與嵌巖段巖層的相對位移、樁與樁端巖石相對位移、樁的長徑比、嵌巖比和樁底清孔情況等。(2)對比目前國內(nèi)使用較為廣泛的三種地基基礎(chǔ)規(guī)范,通過認(rèn)真分析、對比嵌巖樁極限承載力的計算公式,評價了各規(guī)范計算方法的差異性及存在的不足之處。(3)通過對本文收集的試樁進(jìn)行分析匯總,將試樁的嵌巖比、長徑比、土層側(cè)阻力分擔(dān)荷載比、巖層側(cè)阻力分擔(dān)荷載比、樁端阻力分擔(dān)荷載比等經(jīng)過理論分析和數(shù)據(jù)處理。然后應(yīng)用數(shù)理統(tǒng)計學(xué)的曲線擬合法得到軟巖嵌巖樁和硬巖嵌巖樁的土層側(cè)阻系數(shù)、巖層側(cè)阻系數(shù)、端阻系數(shù),并結(jié)合現(xiàn)行公路橋規(guī)對嵌巖樁極限承載力的計算公式,推導(dǎo)出了修正后的嵌巖樁極限承載力的計算公式。(4)針對本文的修正計算公式,將某實際工程案例資料分別代入到現(xiàn)行公路橋規(guī)和經(jīng)驗公式以及本文修正得到的有關(guān)嵌巖樁極限承載力的計算公式中,分別得到相應(yīng)的結(jié)果,并相互對比分析,驗證本文關(guān)于嵌巖樁極限承載力修正計算公式的合理性和可行性。
[Abstract]:Rock-socketed pile foundation has been widely used in high-rise buildings, bridges and other large-scale projects.However, due to the diversity of soil and rock mass characteristics, the complexity of pile-rock interaction, the time-consuming and labor-consuming test of pile test, the high cost and the large dispersion of the obtained data, etc.It is very difficult to achieve accurate results for in-situ test of pile foundation.Therefore, the research on ultimate bearing capacity of rock-socketed piles in current domestic codes is mainly based on the semi-theoretical and semi-empirical formula to calculate the ultimate bearing capacity of rock-socketed piles.According to this situation, it is necessary to study the ultimate bearing capacity of rock-socketed pile.In this paper, 180 test piles are collected and sorted.The typical 38 test piles and 30 soft rock socketed piles and 8 hard rock socketed piles are selected as the basis for deducing the revised formula of ultimate bearing capacity of rock-socketed piles considering the factors such as aspect ratio and rock-socketed ratio.Based on the analysis and calculation of in-situ test data of 38 test piles and the finite element numerical simulation, a modified calculation formula considering the influence of aspect ratio and rock-socketed ratio on ultimate bearing capacity of rock-socketed pile is derived.The main contents of this paper are as follows: (1) by studying the experimental research and literature data of rock-socketed piles at home and abroad, the load-bearing mechanism and load-transfer characteristics of rock-socketed piles are summarized and summarized.The characteristics of vertical bearing capacity of rock-socketed pile and its soil side resistance, pile rock side resistance and pile tip resistance are analyzed. The main factors affecting the vertical ultimate bearing capacity of rock-socketed pile are discussed: the properties of the surrounding soil layer in the upper part of rock-socketed pile.The properties of the rock stratum around the lower pile, the relative displacement of the pile to the surrounding soil, the relative displacement of the rock layer between the pile and the rock-socketed section, the relative displacement of the pile to the rock at the end of the pile, the ratio of length to diameter of the pile,Compared with the three kinds of foundation codes which are widely used in our country at present, through careful analysis, the calculation formula of ultimate bearing capacity of rock-socketed pile is contrasted.This paper evaluates the difference of the calculation methods of various codes and their shortcomings. (3) through the analysis and summary of the test piles collected in this paper, the rock socketed ratio, the aspect diameter ratio, the lateral resistance of the soil layer, the load ratio of the lateral resistance of the rock layer, and the load ratio of the lateral resistance of the rock layer are analyzed and summarized.The load ratio of resistance sharing at the end of the pile is analyzed by theory and data processing.Then the soil lateral resistance coefficient, rock layer lateral resistance coefficient and end resistance coefficient of soft rock socketed pile and hard rock socketed pile are obtained by using the curve fitting method of mathematical statistics, and the calculation formula of ultimate bearing capacity of rock-socketed pile combined with the existing highway and bridge rules is obtained.A modified formula for calculating ultimate bearing capacity of rock-socketed pile is derived.The actual engineering case data are put into the existing highway and bridge rules and empirical formulas respectively, and the calculation formula of ultimate bearing capacity of rock-socketed pile is revised in this paper. The corresponding results are obtained and compared with each other.The rationality and feasibility of the modified formula of ultimate bearing capacity of rock-socketed pile are verified.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：U443.15

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