本文選題：CFG樁 + 復合地基�。� 參考：《中國地質大學(北京)》2015年碩士論文

【摘要】：作為現(xiàn)代高層建筑軟土地基處理的主要手段,CFG樁復合地基以其優(yōu)越的地基加固性能在我國得到了廣泛的應用。同時,我國作為地震高發(fā)的國家,城市的高速發(fā)展深受地震自然災害的制約。因此,對CFG樁復合地基抗震性能的深入研究具有深遠的意義。本文通過對CFG樁復合地基的承載機理及破壞機理的分析,利用LS-DYNA有限元動力學分析軟件,對CFG樁復合地基抗震性能的動力學特性進行了數(shù)值分析研究,同時,進一步研究了CFG樁復合地基設計參數(shù)對CFG樁復合地基抗震性能的影響。本文通過對CFG樁復合地基抗震性能的分析研究,獲得主要成果如下:1)在地震荷載作用下,CFG樁復合地基破壞的判別主要是通過CFG樁復合地基樁體的位移、應力進行判斷。當樁體截面拉應力在樁體截面抗拉強度范圍內,樁頂水平位移在水平位移容許值范圍內時,樁體不會產生破壞,復合地基處于安全狀態(tài)。2)本文建立了地震荷載作用下CFG樁復合地基動力學數(shù)值模型。對地震作用下CFG樁復合地基不同位置樁體及樁間土的水平及豎向加速度、位移、應力進行了對比分析,得到了樁體水平及豎向加速度、位移的變化規(guī)律,同時,得到了樁體及樁間土水平及豎向應力變化規(guī)律:(1)在地震荷載作用下,CFG樁復合地基樁體的水平加速度由樁頂至底部隨深度的增加先減小后增大;(2)水平位移呈現(xiàn)隨深度的增加不斷減小的規(guī)律;(3)水平應力隨深度的增加先增大后減小,同時,邊樁較中心樁的水平應力更大;(4)邊樁產生的豎向加速度比中心樁豎向加速度大;(5)邊樁豎向位移遠大于中心樁的豎向位移;(6)樁體豎向應力隨深度的增加先增大后減小。3)將不同的設計參數(shù)(樁徑、樁長、樁間距)作為變量參數(shù),通過對比分析,得到了各設計參數(shù)對CFG樁復合地基抗震性能的影響:(1)增大樁體直徑可以減小產生的加速度、變形及樁體的水平應力,提高復合地基的抗震性能。但是,這會增大樁體的豎向應力易導致樁體的破壞;(2)增加樁體長度可以減小復合地基受地震波作用所產生的加速度、變形及樁體豎向應力,提高復合地基的抗震性能。但是,這會增大樁體的水平應力導致樁體的破壞;(3)增大樁間距對樁體及樁間土地震作用下所產生的加速度及位移影響很小,同時其應力呈減小的趨勢。
[Abstract]:CFG pile composite foundation, as the main means of soft soil foundation treatment in modern high-rise buildings, has been widely used in China because of its excellent foundation strengthening performance. At the same time, as a country with high incidence of earthquakes, the rapid development of cities is restricted by earthquake natural disasters. Therefore, it is of great significance to study the seismic behavior of CFG pile composite foundation. Based on the analysis of bearing mechanism and failure mechanism of CFG pile composite foundation, the dynamic characteristics of seismic behavior of CFG pile composite foundation are studied numerically by using LS-DYNA finite element dynamic analysis software. The influence of the design parameters of CFG pile composite foundation on the seismic behavior of CFG pile composite foundation is further studied. Based on the analysis of the seismic behavior of the CFG pile composite foundation, the main results are as follows: 1) the main result of judging the damage of the CFG pile composite foundation under the earthquake load is mainly through the displacement and stress of the pile body of the CFG pile composite foundation. When the tensile stress of the pile section is in the range of tensile strength of the pile section and the horizontal displacement of the top of the pile is within the allowable range of the horizontal displacement, the pile body will not be destroyed. In this paper, the dynamic numerical model of CFG pile composite foundation under earthquake load is established. The horizontal and vertical acceleration, displacement and stress of pile and soil in different positions of CFG pile composite foundation under seismic action are compared and analyzed, and the variation law of horizontal and vertical acceleration and displacement of pile body are obtained, at the same time, The rule of horizontal and vertical stress variation of pile and soil between piles is obtained. (1) the horizontal acceleration of CFG pile composite foundation under earthquake load decreases first with the increase of pile depth and then increases with depth.) the horizontal displacement of CFG pile composite foundation decreases with depth and then increases with depth. The horizontal stress increases first and then decreases with the increase of depth. At the same time, Vertical displacement of side pile is much greater than that of central pile.) Vertical stress of side pile increases first and then decreases with the increase of depth. (5) Vertical displacement of side pile is much greater than that of center pile (4) the vertical acceleration of edge pile is greater than that of center pile (5) the vertical displacement of side pile is much greater than that of center pile (4) the vertical stress of side pile increases first and then decreases with the increase of depth. Small. 3) will be different design parameters (pile diameter, By comparing and analyzing the influence of design parameters on seismic behavior of CFG pile composite foundation, the influence of different design parameters on seismic behavior of CFG pile composite foundation is obtained. The increase of pile diameter can reduce the acceleration, deformation and horizontal stress of pile body. Improve the seismic performance of composite foundation. However, this will increase the vertical stress of the pile and lead to the failure of the pile. Increasing the length of the pile can reduce the acceleration, deformation and vertical stress of the composite foundation caused by seismic waves, and improve the seismic performance of the composite foundation. However, this will increase the horizontal stress of the pile and lead to the failure of the pile. (3) increasing the spacing of the pile has little effect on the acceleration and displacement of the pile and the soil between the piles, and its stress tends to decrease.
【學位授予單位】：中國地質大學(北京)
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU470;TU435

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