本文關(guān)鍵詞：大直徑旋挖鉆孔灌注樁載荷試驗及承載性能仿真分析　出處：《長安大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 大直徑旋挖樁 靜載荷試驗 極限預(yù)測 灰色理論 數(shù)值模擬

【摘要】：樁基礎(chǔ)現(xiàn)已發(fā)展成為公路橋梁建設(shè)中廣泛采用的基礎(chǔ)形式,其造價較高通常占橋梁下部結(jié)構(gòu)的1/3以上,因此樁基礎(chǔ)在保證安全耐用的同時也要經(jīng)濟(jì)合理。通過現(xiàn)場靜載試驗手段研究單樁極限承載特性進(jìn)而為樁基設(shè)計參數(shù)優(yōu)化提供參考是最常用且直觀的方法,然而對于大直徑灌注樁,載荷試驗往往難以得到其極限承載特性,根據(jù)不完全試驗數(shù)據(jù)對其承載特性進(jìn)行研究有重要的工程意義。本文依托黃延高速擴(kuò)能工程開展大直徑樁軸向載荷試驗,運用修正的灰色理論模型和有限元軟件結(jié)合試驗結(jié)果對該地區(qū)大直徑旋挖樁極限承載特性展開預(yù)測和分析,主要研究工作如下:(1)參照試驗地工區(qū)工程樁設(shè)計標(biāo)準(zhǔn),在弱濕陷性黃土地基中進(jìn)行豎向靜載試驗,采集室內(nèi)外試驗數(shù)據(jù)并初步分析,總結(jié)該地區(qū)大直徑旋挖樁承載性狀;(2)結(jié)合以往載荷試驗數(shù)據(jù),通過MATLAB實現(xiàn)GM(1,1)預(yù)測模型計算,與常用Q-s曲線預(yù)測方法對比各自預(yù)測精度并分析相對誤差和預(yù)測原理,選用精度最高的修正GM(1,1)預(yù)測模型對本次試驗結(jié)果進(jìn)行預(yù)測。(3)根據(jù)試驗實測數(shù)據(jù),運用ABAQUS建立三維仿真計算模型并考慮載荷試驗中錨樁上拔作用對試樁影響;對比仿真計算結(jié)果與現(xiàn)場試驗數(shù)據(jù),驗證仿真計算模型較為合理。(4)研究靜載試驗中錨樁設(shè)置方式對試樁極限承載力判定的影響,根據(jù)不同的錨樁布置方案分別建立仿真模型研究對試驗結(jié)果影響程度最小的錨樁布設(shè)方式。(5)對影響單樁極限承載力的樁周土體參數(shù)如:變形模量、粘聚力及樁周土體內(nèi)摩擦角及樁體參數(shù)如:樁長、樁徑、樁身彈模進(jìn)行仿真分析,為提高樁基極限承載力的工程手段如:樁端、樁側(cè)后壓漿等工藝提出適用范圍;對比數(shù)值分析結(jié)果,對“合理樁長”和“尺寸效應(yīng)”進(jìn)行了驗證。
[Abstract]:Pile foundation has developed into a widely used foundation form in highway and bridge construction. Its high cost usually accounts for more than 1/3 of the bridge substructure. Therefore, the pile foundation should be economical and reasonable while ensuring safety and durability. It is the most common and intuitive method to study the ultimate bearing characteristics of single pile by static load test in situ and to provide reference for the optimization of design parameters of pile foundation. However, for large diameter cast-in-place piles, it is difficult to obtain their ultimate bearing characteristics by load test. Based on the incomplete test data, it is of great engineering significance to study its bearing characteristics. The axial load test of large diameter pile is carried out based on the Huangyan high-speed capacity expansion project. Using the modified grey theory model and the finite element software combined with the test results, the ultimate bearing characteristics of the large diameter rotary excavated pile in this area are predicted and analyzed. The main research work is as follows: (1) the vertical static load test is carried out in the weak collapsible loess foundation with reference to the design standard of engineering piles in the test site, and the indoor and outdoor test data are collected and analyzed preliminarily. The bearing capacity of large diameter rotary excavated piles in this area is summarized. (2) based on the previous load test data, the calculation of GM-1 / 1) prediction model is realized by MATLAB. Compared with the Q-s curve prediction methods, the relative error and the prediction principle are analyzed. The modified GM(1 with the highest precision is selected. 1) forecasting model is used to predict the test results. (3) according to the measured data of the test, the three-dimensional simulation model is established by using ABAQUS and the influence of uplift action of anchor pile on the test pile is considered in the load test. Comparing the simulation results with the field test data, verify that the simulation calculation model is more reasonable. 4) study the influence of anchoring pile setting mode on the ultimate bearing capacity of test pile in static load test. According to different layout schemes of anchor pile, simulation models were established to study the influence of anchor pile layout mode on the ultimate bearing capacity of single pile, such as deformation modulus. The cohesive force, the internal friction angle of soil around the pile and the parameters of pile body such as pile length, pile diameter and elastic modulus of pile body are simulated and analyzed, so as to improve the ultimate bearing capacity of pile foundation by engineering means such as: pile end. The application range of the technology such as post-grouting on the side of pile is put forward. Compared with the results of numerical analysis, the reasonable pile length and size effect are verified.
【學(xué)位授予單位】：長安大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U443.15

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