發(fā)布時(shí)間：2018-03-22 18:20

  本文選題：軟土　切入點(diǎn)：單樁　出處：《太原理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：群樁基礎(chǔ)作為深基坑土體加固的主要方式之一在工程中日漸增多。但是目前對于群樁基礎(chǔ)的研究存在薄弱環(huán)節(jié),單樁與群樁之間的關(guān)聯(lián)性分析還存在著許多盲目性,例如對于樁基礎(chǔ)的研究不能僅僅考慮沉降方面,對于基樁的軸力、樁端阻力等方面都值得我們進(jìn)行透徹的探討。僅僅由單樁基礎(chǔ)承載力估算的群樁基礎(chǔ)承載力運(yùn)用在樁基礎(chǔ)設(shè)計(jì)中是不可靠的。同時(shí),在正常使用過程中承載能力的不準(zhǔn)確性也會(huì)造成群樁基礎(chǔ)出現(xiàn)大量問題。在運(yùn)用Midas/GTS數(shù)值模擬軟件進(jìn)行模擬過程中,提出了運(yùn)用修正莫爾—庫倫本構(gòu)模型能夠更好的模擬軟土地層,避免了對樁基礎(chǔ)模擬出現(xiàn)的偏差,提高了數(shù)值模擬結(jié)果的準(zhǔn)確性。以Midas/GTS數(shù)值模擬為主要試驗(yàn)手段,《建筑樁基技術(shù)規(guī)范》JGJ94-2008為試驗(yàn)依據(jù),對單樁基礎(chǔ)進(jìn)行模擬試驗(yàn),討論了單樁基礎(chǔ)處于軟質(zhì)地基土中,在受荷載狀態(tài)下的承載力性狀。揭示了樁身軸力隨著樁體埋深的增加而減小,樁身側(cè)摩阻力承擔(dān)荷載百分比要大于樁端阻力。采用規(guī)范中單樁豎向極限承載力經(jīng)驗(yàn)參數(shù)法對模擬的單樁試驗(yàn)結(jié)果進(jìn)行驗(yàn)證,證實(shí)試驗(yàn)?zāi)Ｐ偷臏?zhǔn)確可靠。采用數(shù)值模擬的方法對樁間距為2.5d、樁長為15m的9根方格樁處于軟土地基時(shí)的模型進(jìn)行分析,討論了群樁基礎(chǔ)基樁中中心樁、邊樁和角樁之間的差別,揭示了在同一承臺(tái)下中心樁的沉降量最大,邊樁次之,角樁最小。對于樁體軸力的分析,則呈現(xiàn)出角樁大于邊樁大于中心樁的特征現(xiàn)象。樁身側(cè)摩阻力承擔(dān)荷載百分比方面中心樁承擔(dān)最多,邊樁次之,角樁最小,樁端阻力的承擔(dān)荷載百分比反之。對于9根方格群樁下基樁樁間距的不同進(jìn)行數(shù)值模擬試驗(yàn)分析,分別對群樁的沉降量、樁身軸力以及樁端阻力進(jìn)行討論,表現(xiàn)出當(dāng)樁間距為3倍的基樁直徑時(shí)群樁基礎(chǔ)的承載能力為最優(yōu)。針對基樁長度不同采用數(shù)值模擬的手段進(jìn)行群樁基礎(chǔ)承載力的對比討論,從基樁的沉降量、樁身軸力以及樁端阻力方面分析出隨著樁長的增加群樁基礎(chǔ)承載力具有增加的趨勢,但是樁長過長不會(huì)對群樁基礎(chǔ)產(chǎn)生較大的有利效果。選定影響群樁基礎(chǔ)承載力的主要因素為基樁樁間距和基樁長度,將單樁基礎(chǔ)與群樁基礎(chǔ)的承載力進(jìn)行對比并探究之間的關(guān)系。在此基礎(chǔ)上提出了單樁基礎(chǔ)與群樁基礎(chǔ)之間承載能力的關(guān)聯(lián)性公式,為實(shí)際工程中估算群樁基礎(chǔ)承載力提供了科學(xué)依據(jù)。
[Abstract]:Pile group foundation, as one of the main methods of soil reinforcement in deep foundation pit, is increasing day by day in engineering. However, the research on pile group foundation is weak at present, and the correlation analysis between single pile and pile group still has a lot of blindness. For example, the study of pile foundation should not only consider settlement, but also the axial force of foundation pile. The pile end resistance and so on are all worth our thorough discussion. It is not reliable to use the bearing capacity of group pile foundation which is estimated by single pile foundation bearing capacity in pile foundation design, at the same time, The inaccuracy of bearing capacity in normal use will also cause a lot of problems in pile group foundation. In the process of simulation using Midas/GTS numerical simulation software, It is proposed that the modified Mohr-Coulomb constitutive model can better simulate the soft soil layer and avoid the deviation of the pile foundation simulation. The accuracy of the numerical simulation results is improved. With Midas/GTS numerical simulation as the main test means and JGJ94-2008 as the test basis, the single pile foundation is simulated, and the single pile foundation is in the soft foundation. It is revealed that the axial force of the pile decreases with the increase of the buried depth of the pile. The bearing load percentage of lateral friction of pile is larger than that of pile tip. The empirical parameter method of vertical ultimate bearing capacity of single pile in the code is used to verify the simulated results of single pile test. It is proved that the test model is accurate and reliable. The numerical simulation method is used to analyze the model of 9 lattice piles with a distance of 2.5 days and a pile length of 15 m in soft soil foundation. The difference among the central pile, side pile and corner pile in pile foundation of group pile foundation is discussed. It is revealed that the settlement of the central pile under the same cap is the largest, the side pile is the second, the angle pile is the least. It shows that the angular pile is larger than the edge pile than the central pile, and the center pile bears the most load percentage, the edge pile takes the second place, and the angle pile is the smallest. The bearing load percentage of pile tip resistance is vice versa. Numerical simulation tests are carried out on the different spacing of foundation pile under 9 square pile groups. The settlement of pile group, the axial force of pile body and the resistance of pile end are discussed, respectively. It is shown that the bearing capacity of pile group foundation is optimal when the pile spacing is 3 times the diameter of foundation pile. The bearing capacity of pile group foundation is discussed by numerical simulation according to the difference of pile length, and the settlement of pile group is discussed according to the settlement of foundation pile. According to the axial force of pile body and the resistance of pile tip, the bearing capacity of pile group foundation increases with the increase of pile length. But the pile length is too long will not have a great beneficial effect on the pile group foundation. The main factors that affect the bearing capacity of the pile group foundation are the pile spacing and the pile length. The bearing capacity of single pile foundation and group pile foundation is compared and the relationship between the bearing capacity of single pile foundation and group pile foundation is discussed, and the correlation formula of bearing capacity between single pile foundation and pile group foundation is put forward. It provides a scientific basis for estimating the bearing capacity of pile group foundation in practical engineering.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU473.1

【參考文獻(xiàn)】

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本文編號(hào)：1649826