本文選題：大直徑樁 + 靜載試驗��； 參考：《昆明理工大學》2010年碩士論文

【摘要】：隨著我國基本建設(shè)事業(yè)的迅速發(fā)展,樁基礎(chǔ)在高層建筑、重型廠房、橋梁、港口碼頭、海上采油平臺以及核電站等工程中應(yīng)用廣泛。樁基礎(chǔ)朝著大直徑高承載力的方向發(fā)展,大直徑樁的檢測也越來越重要。 本文依托沈陽新世界會展中心一期試樁檢測工程,該樁樁徑0.85m、樁長52.0m、長徑比為56～62屬大直徑長樁。由于此前本地區(qū)未有類似的工程,施工及檢測經(jīng)驗缺乏,需通過試驗結(jié)果來驗證設(shè)計,以保證工程質(zhì)量。 本文采用目前最直接、最可靠的檢測方法--基樁靜載試驗法進行承載力測定,得出的Q-s曲線為緩變型,且該工程中樁的長度變化并沒有引起樁的Q-s曲線發(fā)生太大的波動,表明增加樁長對于承載力的提高不明顯,還不利于沉降控制。若要改進設(shè)計需綜合考慮樁長、樁徑,選擇合適的長徑比�？蛇m當縮短樁長至44m,改變長徑比以便發(fā)揮端阻作用、降低成本。并針對該地區(qū)的地層結(jié)構(gòu)近似地將該地區(qū)的砂土地基視為同一介質(zhì)的地基。通過回歸分析得出了Y=A+B×X公式和A=C+D×L；B=C+D×L公式,能有效描述該地區(qū)類似土層介質(zhì)條件下樁身軸力與深度變化關(guān)系,對本地區(qū)或類似的工程有一定的借鑒作用。 針對成樁過程中可能出現(xiàn)斷樁、離析等情況的缺陷樁。經(jīng)過與其他完整性檢測方法的對比,選擇了適合于本工程樁身的完整性檢測的方法—低應(yīng)變反射波‘法。該法具有快速、經(jīng)濟、可大面積普查等特點。由于現(xiàn)場的檢測條件復(fù)雜,影響因素較多,難以得到非常標準的完整檢測波形,本文采用了通過聯(lián)系地質(zhì)情況分析實測波形的方法對其樁身完整性類別作出了判斷,綜合判別為Ⅰ類樁。 因現(xiàn)場試驗用樁均為工作用樁,不可以也不可能進行破壞性試驗,因而本文運用FLAC 3D(三維快速拉格朗日法)對樁進行了破壞性模擬分析,采用結(jié)合地質(zhì)報告提供的力學參數(shù)以模擬結(jié)果與樁承載試驗結(jié)果基本一致為原則,并將模擬結(jié)果與實測數(shù)據(jù)進行比對,對參數(shù)不斷調(diào)整,最終確定了與實際相近的模擬參數(shù)。以此進行樁極限承載數(shù)值模擬,得到了樁的極限承載力,并提出了后壓漿及擴大頭的優(yōu)化設(shè)計方案,同時對該方案進行數(shù)值模擬,所得結(jié)果表明可以縮短樁長、減小鋼筋用量、節(jié)省了工程費用。并為本地區(qū)類似樁基工程的設(shè)計和施工提供了一定的參考依據(jù)。
[Abstract]:With the rapid development of capital construction in China, pile foundation is widely used in high-rise building, heavy plant, bridge, port wharf, offshore oil recovery platform and nuclear power plant. The pile foundation is developing towards the direction of large diameter and high bearing capacity, and the detection of large diameter pile is becoming more and more important. This paper relies on the first phase test pile test project of Shenyang New World Convention and Exhibition Center. The pile diameter is 0.85 m, pile length is 52.0 m, and the ratio of length to diameter is 560.62 belong to large diameter long pile. Due to the lack of construction and testing experience in this area, the design should be verified by test results to ensure the quality of the project. In this paper, the most direct and reliable testing method, the static load test method of foundation pile, is used to measure the bearing capacity. The Q-s curve obtained is of a slowly modified type, and the change of pile length in the project does not cause too much fluctuation of the Q-s curve of the pile. It shows that the increase of pile length is not obvious for the increase of bearing capacity and is not conducive to settlement control. In order to improve the design, it is necessary to consider the pile length and diameter and choose the appropriate ratio of length to diameter. The length of the pile can be shortened to 44m and the aspect ratio can be changed in order to play the role of end resistance and reduce the cost. According to the stratigraphic structure of this area, the sand foundation in this area is regarded as the foundation of the same medium. By regression analysis, the formulas of Ya A B 脳 X and A C D 脳 L are obtained, which can effectively describe the relationship between the axial force and the depth of the pile under the condition of similar soil layer in this area, and can be used for reference in this area or similar projects. The defect pile may appear in the process of pile formation, such as broken pile, segregation and so on. By comparing with other integrity detection methods, the method of low strain reflected wave is selected for the integrity detection of pile body in this project. The method has the characteristics of fast, economical and large area census. Because of the complex testing conditions and many influencing factors on the spot, it is difficult to obtain a very standard complete detection waveform. In this paper, the integrity of pile body is judged by the method of analyzing the measured waveform by connecting with the geological conditions. Comprehensive discrimination is classified as class I pile. Because all the piles used in field test are working piles, it is not possible and impossible to carry out destructive tests. In this paper, FLAC 3D (three dimensional fast Lagrangian method) is used to simulate and analyze the damage of piles. The mechanical parameters provided by the geological report are taken as the principle that the simulation results are basically consistent with the pile bearing test results, and the simulation results are compared with the measured data, the parameters are adjusted continuously, and the simulation parameters close to the actual ones are finally determined. The ultimate bearing capacity of pile is obtained by numerical simulation, and the optimum design scheme of post-grouting and enlarged head is put forward. The results show that the length of pile can be shortened and the amount of steel bar can be reduced. The cost of the project was saved. It also provides some reference for the design and construction of similar pile foundation engineering in this area.
【學位授予單位】：昆明理工大學
【學位級別】：碩士
【學位授予年份】：2010
【分類號】：TU473.16

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