【摘要】：短樁承臺(tái)式基礎(chǔ)是一種上部為開(kāi)挖式基礎(chǔ)、下部為短樁并且考慮共同受力的新型基礎(chǔ)型式。在樁基設(shè)計(jì)的過(guò)程中,通過(guò)考慮承臺(tái)下地基土反力,應(yīng)用短樁優(yōu)化樁基設(shè)計(jì),從而使得樁基極限承載力有很大提升。該新型基礎(chǔ)型式在某些特定地質(zhì)復(fù)雜地區(qū)有著重要的實(shí)用價(jià)值,通過(guò)該種型式的樁基優(yōu)化,使得樁基基礎(chǔ)既符合安全性又符合經(jīng)濟(jì)性的要求。論文通過(guò)資料調(diào)研、對(duì)比、總結(jié)的方式界定了短樁的定義,并通過(guò)FLAC3D數(shù)值模擬軟件模擬了不同樁長(zhǎng)(L=2m,3m,4m,4.5m,5m,5.5m,6m,7m,8m,9m,10m,11m)的單樁豎向承載力,當(dāng)樁長(zhǎng)L4m時(shí),其承載力較低;當(dāng)樁長(zhǎng)為4m～6m時(shí),較L4m時(shí)其承載力上升幅度較大,大概提高35%左右。而當(dāng)樁長(zhǎng)L6m時(shí),其承載力并沒(méi)有顯著提升。綜上,本文界定了所討論的短樁為長(zhǎng)度為4m≤L≤6m,且長(zhǎng)徑比6L/D20的樁。系統(tǒng)分析了短樁與土共同作用的受力狀態(tài),研究了承臺(tái)與地基土共同作用機(jī)理,通過(guò)FLAC3D數(shù)值模擬進(jìn)行短樁承臺(tái)式基礎(chǔ)群樁模擬實(shí)驗(yàn),模擬了短樁不同樁長(zhǎng)(L=4m、5m、6m),不同樁距(Sa=2d、3d、4d、6d)的短樁群樁承臺(tái)土反力的變化。得出承臺(tái)土反力與樁距成正比,當(dāng)樁距Sa=4d～6d時(shí),承臺(tái)土能充分發(fā)揮作用,承臺(tái)土反力基本不受樁長(zhǎng)影響。承臺(tái)反力的數(shù)值最大處在邊柱內(nèi)側(cè)附近,其次為承臺(tái)角點(diǎn),再次為承臺(tái)邊緣處,群樁內(nèi)部最小。為研究不同土層組合對(duì)短樁承臺(tái)式基礎(chǔ)的影響研究,進(jìn)行在不同土層組合條件下短樁承臺(tái)群樁模擬實(shí)驗(yàn)。測(cè)試包括不同承臺(tái)下土變化(粘土、砂土、圓礫土)、不同樁端土變化(粘土、砂土、圓礫土),分析土層變化對(duì)承臺(tái)分擔(dān)荷載比例及短樁承臺(tái)式基礎(chǔ)沉降量的影響,及二者之間的聯(lián)系。實(shí)驗(yàn)得出,粘土層承臺(tái)分擔(dān)荷載比最大且沉降量最小。通過(guò)對(duì)不同土層組合Q-s曲線及承臺(tái)分擔(dān)荷載比曲線的分析比較,發(fā)現(xiàn)沉降量較小的土層組合承臺(tái)分擔(dān)荷載比較大�；谝陨涎芯砍晒�,本文認(rèn)為短樁承臺(tái)式基礎(chǔ)應(yīng)為淺基礎(chǔ)的優(yōu)化型式,根據(jù)整體承載能力和沉降量雙重控制標(biāo)準(zhǔn)的設(shè)計(jì)原則,整體設(shè)計(jì)思路為:從天然地基設(shè)計(jì)出發(fā),在滿足地基承載力的條件下,為了減少沉降而設(shè)置一定數(shù)量的短樁�；诖搜芯抗餐饔迷O(shè)計(jì)方法及關(guān)鍵數(shù)據(jù)取值,完成短樁-承臺(tái)-土共同作用設(shè)計(jì)流程。使用短樁-承臺(tái)-土共同作用設(shè)計(jì)方法對(duì)實(shí)際工程進(jìn)行重新設(shè)計(jì),并通過(guò)數(shù)值模擬軟件予以驗(yàn)證。最后根據(jù)以上研究理論及短樁-承臺(tái)-土共同作用設(shè)計(jì)方法,使用VB6.0編程軟件完成"短樁承臺(tái)式基礎(chǔ)"設(shè)計(jì)程序的編制,使得該基礎(chǔ)型式的設(shè)計(jì)工程簡(jiǎn)單高效,提高在實(shí)際工程中的應(yīng)用效率。
[Abstract]:Short pile cap foundation is a new type of foundation which is excavated in the upper part and short pile in the lower part. In the process of pile foundation design, the pile foundation design is optimized by considering the reaction force of foundation soil under the pile cap, so that the ultimate bearing capacity of pile foundation can be greatly improved. This new type of foundation has important practical value in some special geological complex areas. Through the optimization of this type of pile foundation, the pile foundation not only meets the requirements of safety but also meets the requirements of economy. In this paper, the definition of short pile is defined by means of data investigation, comparison and summary, and the vertical bearing capacity of single pile with different pile lengths (L ~ (2) m ~ (3) ~ (3) m ~ (4) ~ (4.5) m ~ (5) ~ (5) m ~ (6) ~ (6) m ~ (?) ~ (8) m ~ (9) ~ (10) m ~ (11 m) is simulated by FLAC3D numerical simulation software. When the length of pile is L ~ (4) m, its bearing capacity is lower. Compared with L _ 4 m, the bearing capacity increases by about 35%. However, when the pile length is L6 m, the bearing capacity does not increase significantly. In summary, this paper defines the discussed short pile as a pile whose length is 4m 鈮，

本文編號(hào)：2274453