【摘要】：本文根據(jù)凍土區(qū)輸電線路桿塔基礎(chǔ)的設(shè)計(jì)原則和五道梁地區(qū)的凍土特性，選擇了兩種桿塔基礎(chǔ)——錐柱基礎(chǔ)和預(yù)制管樁基礎(chǔ)進(jìn)行現(xiàn)場(chǎng)真型試驗(yàn)。試驗(yàn)分為凍結(jié)期和融化期兩個(gè)部分，每個(gè)時(shí)期分上拔和水平、下壓和水平兩種工況進(jìn)行。通過(guò)對(duì)樁基礎(chǔ)的位移、內(nèi)力、土側(cè)壓力的觀測(cè)，得到Q～s曲線圖和分級(jí)荷載下不同斷面的軸力圖。經(jīng)過(guò)研究分析，發(fā)現(xiàn)錐柱基礎(chǔ)的承載性能良好，基礎(chǔ)選型及設(shè)計(jì)合理，可用作青�！鞑刂绷鬏旊娋�路工程的線路基礎(chǔ)。而管樁基礎(chǔ)截面規(guī)則，側(cè)壁光滑，抗拔性能較差，不能用作上拔荷載較大的輸電線路基礎(chǔ)。通過(guò)試驗(yàn)和理論計(jì)算，推導(dǎo)出了適合在風(fēng)荷載較大的多年凍土地區(qū)使用的樁基礎(chǔ)極限承載力公式。 由于凍士參數(shù)不易從實(shí)驗(yàn)中獲取，為了采用有限元模型計(jì)算，本文運(yùn)用BP神經(jīng)網(wǎng)絡(luò)進(jìn)行參數(shù)反演，得出摩爾庫(kù)侖本構(gòu)模型的凍土力學(xué)參數(shù)值。據(jù)此建立了錐柱基礎(chǔ)在凍土中的三維有限元模型，得到了錐柱基礎(chǔ)在凍土中的豎向和水平位移云圖，并與真型試驗(yàn)得出的結(jié)論做對(duì)比，驗(yàn)證了模型的準(zhǔn)確性和適用性。根據(jù)有限元模型分析得出：融土深度為2m時(shí)，對(duì)錐柱基礎(chǔ)的下壓極限承載力和豎向位移影響較小，，但對(duì)錐柱基礎(chǔ)的上拔極限承載力和上拔位移影響較大。
[Abstract]:According to the design principle of transmission line tower foundation in frozen soil area and the frozen soil characteristics of Wudaoliang area, two kinds of tower foundation, cone-column foundation and prefabricated pipe-pile foundation, are selected for field test. The experiment is divided into two parts: freezing period and thawing period, each period is divided into two working conditions: up-drawing and horizontal, down-pressure and horizontal. Based on the observation of displacement, internal force and lateral pressure of pile foundation, the QS curves and axial diagrams of different sections under graded loads are obtained. Through the research and analysis, it is found that the cone column foundation has good bearing capacity, reasonable selection and design of the foundation, and can be used as the line foundation of Qinghai-Tibet HVDC transmission line engineering. The section of pipe pile foundation is regular, the side wall is smooth, and the pull-out resistance is poor, so it can not be used as the transmission line foundation with higher uplift load. Through experiment and theoretical calculation, the formula of ultimate bearing capacity of pile foundation is derived, which is suitable to be used in permafrost area with large wind load. In order to use the finite element model to calculate the parameters of frozen soil, BP neural network is used to inverse the parameters, and the mechanical parameters of frozen soil of Mohr-Coulomb constitutive model are obtained. Based on this, a three-dimensional finite element model of cone-column foundation in permafrost is established, and the vertical and horizontal displacement cloud images of cone-column foundation in frozen soil are obtained. The accuracy and applicability of the model are verified by comparing with the conclusion of true test. According to the analysis of finite element model, it is found that when the depth of melted soil is 2m, the influence on the ultimate bearing capacity and vertical displacement of cone column foundation is small, but it has great influence on the ultimate bearing capacity and uplift displacement of cone column foundation.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類(lèi)號(hào)】：TU445;TU473.1

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