發(fā)布時間：2018-05-25 03:24

  本文選題：剛性樁復(fù)合地基 + 變剛度調(diào)平��； 參考：《太原理工大學(xué)》2015年碩士論文

【摘要】：高層建筑中地基基礎(chǔ)的設(shè)計是比較復(fù)雜的問題，特別是在土質(zhì)較差的地區(qū)，隨著建筑高度的增大，上部荷載逐漸增加，會引起地基基礎(chǔ)的不均勻沉降，使得基礎(chǔ)和上部結(jié)構(gòu)產(chǎn)生較大的內(nèi)力，這對于基礎(chǔ)的合理設(shè)計提出很大的挑戰(zhàn)。針對以上問題，設(shè)計師提出變剛度剛性樁復(fù)合地基調(diào)平的概念，通過調(diào)整地基或者樁基的豎向支承剛度分布，促使差異沉降減到最小，基礎(chǔ)或者承臺內(nèi)力和上部結(jié)構(gòu)次應(yīng)力顯著降低。同時使地基基礎(chǔ)達到承載力和抗震要求、降低工程造價的綜合效果，目前已在實際工程中逐漸推廣。 本文采用土體-上部結(jié)構(gòu)動力相互作用的方法，基于ABAQUS有限元分析軟件，對變剛度剛性樁復(fù)合地基-基礎(chǔ)筏板-上部結(jié)構(gòu)進行整體有限元動力時程分析，，分析總結(jié)變剛度剛性樁復(fù)合地基抗震性能和上部結(jié)構(gòu)地震動力響應(yīng)的變化規(guī)律，具體內(nèi)容包括以下幾方面： （1）文章對剛性樁復(fù)合地基動力分析的方法進行探討，基于ABAQUS對復(fù)合地基-筏板基礎(chǔ)-上部結(jié)構(gòu)整體有限元模型進行建立，并對建模過程中樁-土-上部結(jié)構(gòu)動力相互作用的關(guān)鍵性問題進行探討。 （2）通過采用分塊Lanczos法對整體模型進行地震模態(tài)計算，得出：隨著復(fù)合地基筏板兩側(cè)豎向支承剛度的減小，體系對應(yīng)的陣型固有頻率減小，固有周期增大。 （3）對變剛度剛性樁復(fù)合地基的調(diào)平原理進行初步分析，在自重荷載作用下，基礎(chǔ)筏板沉降呈現(xiàn)碟形分布特性，表現(xiàn)為中心沉降較大，邊緣沉降較小的特點；經(jīng)過變剛度調(diào)平設(shè)計優(yōu)化，對筏板基礎(chǔ)能夠進行有效的調(diào)平，減小差異沉降，降低內(nèi)力。 （4）采用時程分析法對剛性樁復(fù)合地基變剛度調(diào)平前后樁體的地震動力響應(yīng)進行分析。變剛度調(diào)平前，邊樁的最大彎矩、最大軸力和相對水平位移均大于中間樁；變剛度調(diào)平后，長樁的彎矩和水平位移遠(yuǎn)大于短樁，長樁彎矩有多個峰值，最大彎矩發(fā)生在復(fù)合地基變剛度處，故要加強邊樁和樁身變剛度處的強度設(shè)計。 （5）采用時程分析法對剛性樁復(fù)合地基變剛度調(diào)平前后基礎(chǔ)和上部結(jié)構(gòu)的地震動力響應(yīng)進行分析。在地震水平力作用下，調(diào)平前后筏板基礎(chǔ)的差異沉降和內(nèi)力均增大，二次差異沉降和基礎(chǔ)內(nèi)力隨著筏板兩側(cè)豎向支承剛度的減小而增大；上部結(jié)構(gòu)的地震動力響應(yīng)隨著筏板兩側(cè)豎向支承剛度的減小而增大。同時總結(jié)了變剛度剛性樁復(fù)合地基抗震性能的優(yōu)劣，并對實際工程提出一些有價值的具體建議。
[Abstract]:The design of foundation is a complicated problem in high-rise building, especially in the area of poor soil quality, with the increase of building height, the upper load increases gradually, which will cause the uneven settlement of foundation. It makes the foundation and superstructure produce larger internal force, which poses a great challenge to the reasonable design of foundation. In view of the above problems, designers put forward the concept of variable stiffness rigid pile composite ground tone level. By adjusting the vertical support stiffness distribution of foundation or pile foundation, the differential settlement is reduced to the minimum. The internal force of foundation or cap and the secondary stress of superstructure are significantly reduced. At the same time, the foundation can meet the requirements of bearing capacity and seismic resistance, and reduce the comprehensive effect of engineering cost, which has been gradually popularized in practical engineering. In this paper, the method of soil-superstructure dynamic interaction is used to analyze the dynamic history of variable stiffness rigid pile composite foundation, raft and superstructure based on ABAQUS finite element analysis software. This paper analyzes and summarizes the variation law of seismic behavior and superstructure dynamic response of variable stiffness rigid pile composite foundation, including the following aspects: In this paper, the dynamic analysis method of rigid pile composite foundation is discussed, and the integral finite element model of composite foundation, raft foundation and superstructure is established based on ABAQUS. The key problem of pile-soil-superstructure dynamic interaction in modeling process is discussed. 2) by using block Lanczos method to calculate the seismic modes of the whole model, it is concluded that with the decrease of vertical support stiffness on both sides of the raft, the corresponding natural frequency of the system decreases and the natural period increases. 3) the leveling principle of variable stiffness rigid pile composite foundation is preliminarily analyzed. Under the action of deadweight load, the settlement of foundation raft presents the characteristics of dish shape distribution, which shows that the center settlement is large and the edge settlement is small. Through the optimization of variable stiffness leveling design, the raft foundation can be effectively leveled, the differential settlement can be reduced, and the internal force can be reduced. 4) the seismic dynamic response of pile body before and after variable stiffness leveling of rigid pile composite foundation is analyzed by time history analysis method. Before leveling with variable stiffness, the maximum moment, maximum axial force and relative horizontal displacement of the side pile are greater than those of the intermediate pile, and the bending moment and horizontal displacement of the long pile are much larger than those of the short pile after the variable stiffness leveling, and the bending moment of the long pile has multiple peaks. The maximum bending moment occurs at the variable stiffness of composite foundation, so the strength design of side pile and pile body should be strengthened. 5) the seismic dynamic responses of foundation and superstructure before and after leveling the variable stiffness of rigid pile composite foundation are analyzed by time-history analysis method. Under the action of seismic horizontal force, the differential settlement and internal force of raft foundation increase before and after leveling, and the secondary differential settlement and foundation internal force increase with the decrease of vertical support stiffness on both sides of raft. The seismic dynamic response of superstructure increases with the decrease of vertical support stiffness on both sides of raft. At the same time, the merits and demerits of the composite foundation with variable stiffness and rigid pile are summarized, and some valuable suggestions for practical engineering are put forward.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU470;TU435

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