發(fā)布時間：2018-04-18 10:05

  本文選題：長螺旋鉆孔壓灌樁 + 螺紋樁�。� 參考：《廣西大學》2017年碩士論文

【摘要】：基于南寧盆地地層組合模型,本文對長螺旋鉆孔壓灌樁和螺紋樁的適用性進行了研究。為此,試驗小組歷時一年多選擇在兩個相同地層組合中組織了兩類似設計參數(shù)的試驗樁進行了相應的工程試驗。并從兩類樁的承載機理、施工控制、技術特點、工程試驗結果等多方面進行了詳細分析、計算和研究。得出如下結論:(1)長螺旋鉆孔壓灌樁和螺紋樁在工程實踐中均以中小直徑樁出現(xiàn),兩類樁在施工工藝、壓灌混凝土、鋼筋籠植入、現(xiàn)場施工文明度等方面具有相同或相似的特點。但在承載機理、成樁機械、成樁質(zhì)量控制要點、造價方面相差較大。(2)兩類樁成樁設備均存在入巖困難,但長螺旋鉆孔壓灌樁樁機入巖困難不僅不會降低其單樁承載力,反而有助于提高其單樁承載力;而螺紋樁樁機一旦出現(xiàn)入巖(或鉆進)困難,則對其單樁承載力影響較大。(3)通過兩個類似地層組合場地及類似設計參數(shù)的基樁試驗,長螺旋鉆孔壓灌樁通過選擇好的樁端持力層,適當加大混凝土的壓灌力,可以顯著提高單樁承載力。而螺紋樁在螺紋段成孔或成樁過程中,如果不能采用同步技術,則作為單樁承載力主要來源的螺紋段承載力下降較大,該部位的承載力僅有正常成樁時的46%左右。(4)當螺紋樁螺紋段螺牙間土受到擾動后,螺紋樁螺紋段的樁側阻力相當于樁徑為螺紋樁內(nèi)徑的干作業(yè)鉆孔樁的樁側阻力,并通過對試驗結果參數(shù)的分析,對螺紋樁技術規(guī)范的公式參數(shù)進行了修正,提出了螺紋樁單樁承載力下限值計算公式。(5)如果減小螺紋樁的入巖深度,保證螺紋段正常形成,則螺紋樁應用于地基處理具有相對優(yōu)勢。(6)在現(xiàn)階段,兩類樁樁機均存在入巖困難的前提下,在南寧盆地典型組合地層(Ⅰ、Ⅱ級階地)上,長螺旋鉆孔壓灌樁具有比螺紋樁更好的適用性。兩類樁在南寧盆地的高階地(泥巖型)地層組合作為工程樁則適用性均較差。
[Abstract]:Based on the stratigraphic combination model of Nanning Basin, this paper studies the applicability of long spiral bored pile and threaded pile.For this reason, the test group took more than one year to select two test piles with similar design parameters in two same strata assemblages to carry out corresponding engineering tests.The bearing mechanism, construction control, technical characteristics and engineering test results of the two kinds of piles are analyzed, calculated and studied in detail.The conclusions are as follows: (1) the long spiral bored pile and the threaded pile all appear as medium and small diameter piles in engineering practice. The two kinds of piles have the same or similar characteristics in construction technology, pressure pouring concrete, steel cage implantation, field construction civilization and so on.However, there are two kinds of piling equipment, such as bearing mechanism, piling machinery, pile quality control points, and cost difference. There are two kinds of pile-forming equipment, which are difficult to enter rock. However, the difficulty of drilling pile machine with long helical drilling hole does not reduce the bearing capacity of single pile.On the contrary, it helps to improve the bearing capacity of single pile, but once the screw pile machine is difficult to enter rock (or drill), the bearing capacity of single pile will be greatly affected by two similar ground combined sites and similar design parameters.The bearing capacity of single pile can be significantly increased by selecting a good bearing layer at the end of the pile and properly increasing the compressive force of concrete.However, if the synchronous technology is not adopted, the bearing capacity of the thread section, which is the main source of the bearing capacity of single pile, will decrease greatly in the process of forming holes or piles in the thread section.The bearing capacity of this part is only about 46% of that of the normal pile formation.) when the soil between the screw teeth of the threaded pile is disturbed, the pile side resistance of the threaded thread section is equal to the pile side resistance of the drilled drilled pile whose diameter is the inner diameter of the threaded pile.Based on the analysis of the parameters of the test results, the formula parameters of the technical specification for threaded pile are revised, and the formula of the lower limit value of bearing capacity of single pile with threaded pile is put forward. (5) if the penetration depth of the threaded pile is reduced, the normal formation of the threaded section can be ensured.Therefore, the application of threaded pile in foundation treatment has a relative advantage. At the present stage, both kinds of pile machines are difficult to enter rock, and on the typical assemblage strata (鈪，

本文編號：1767895