本文選題：裝配結(jié)構(gòu)　切入點：基坑　出處：《中國地質(zhì)大學(xué)(北京)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：裝配式基坑支護結(jié)構(gòu)能夠?qū)崿F(xiàn)方便施工、縮短工期、節(jié)約成本的目的,在盾構(gòu)、頂管等地下工程施工中的豎井支護工程中得到了廣泛應(yīng)用。盾構(gòu)、頂管工程中的豎井?dāng)?shù)量多、工期緊、規(guī)格單一、環(huán)境復(fù)雜、安全要求高,且屬于臨時性工程,在工程完成后需要進行支護結(jié)構(gòu)拆除和基坑回填處理,這正是裝配式支護結(jié)構(gòu)的優(yōu)點。前期研究成果主要集中在單一構(gòu)件或單層拼裝結(jié)構(gòu)的強度和受力特性,但是對于通過環(huán)向和豎向連接構(gòu)件組合而成的圓筒形結(jié)構(gòu)體系的整體受力性能尚缺乏研究。此外,裝配式結(jié)構(gòu)施工中其支護深度滯后于開挖深度一定距離(單次開挖深度),越向下開挖,單次開挖后尚未支護前的臨空面的穩(wěn)定性越差,需要明確給定單次開挖深度下基坑能保持穩(wěn)定的最大開挖深度。采用SAP2000結(jié)構(gòu)有限元程序建立由標(biāo)準(zhǔn)鋼板構(gòu)件、環(huán)向預(yù)緊構(gòu)件和豎向連接構(gòu)件組成的三維結(jié)構(gòu)有限元模型,根據(jù)裝配式支護體系的結(jié)構(gòu)特點,按JGJ130-2011《建筑施工扣件式鋼管腳手架安全技術(shù)規(guī)范》對裝配式支護結(jié)構(gòu)在永久荷載和施工荷載的多種組合工況下的受力和變形進行分析。結(jié)果表明,在不利荷載組合工況下的裝配式支護結(jié)構(gòu)承載力具有足夠安全儲備,能夠滿足規(guī)范要求。基于PLAXIS2D巖土有限元程序構(gòu)建了考慮土-結(jié)構(gòu)-地下水相互作用的基坑數(shù)值模型,模擬裝配式結(jié)構(gòu)支護基坑分層開挖、分層支護的施工過程,重點分析了不同單次開挖深度對基坑最大開挖深度的影響,得到以下結(jié)論:在砂性土和軟土層中,隨著基坑的單次開挖深度的增加,基坑最大開挖深度依次減小。在粘性土層中,由于粘性土的粘聚力、內(nèi)摩擦角以及土體剛度參數(shù)對基坑的最大開挖深度的影響較大,基坑的單次開挖深度對基坑的對大開挖深度影響并不明顯。但在軟土層中,由于單次開挖深度越大,暴露出的臨空面越多,而軟土的剛度較小,易發(fā)生變形,因此臨空面處的土體容易達(dá)到破壞狀態(tài),進而導(dǎo)致軟土層中基坑的最大開挖深度的值相對較小。
[Abstract]:The prefabricated foundation pit supporting structure can realize the purpose of convenient construction, shorten the construction period and save the cost. It has been widely used in the shaft support engineering in the underground engineering such as shield, pipe jacking and so on. There are many vertical wells in shield and pipe jacking engineering. The construction period is tight, the specification is single, the environment is complex, the safety requirement is high, and belongs to the temporary project. After the completion of the project, it is necessary to carry out the demolition of the supporting structure and the treatment of the foundation pit backfill. This is the advantage of the assembled support structure. The previous research results mainly focus on the strength and mechanical characteristics of the single component or monolayer assembly structure. However, there is a lack of research on the overall mechanical behavior of the cylindrical structural system formed by the combination of annular and vertical connection members. In the construction of prefabricated structure, the support depth lags behind the excavation depth (the lower the excavation depth is, the worse the stability of the goaf surface before the excavation is not supported, the lower the excavation depth is, the lower the excavation depth is. It is necessary to make sure that the maximum excavation depth of the foundation pit can be kept stable under the order excavation depth. A three-dimensional structural finite element model consisting of standard steel plate member, circumferential preload member and vertical connection member is established by using SAP2000 structural finite element program. According to the structural characteristics of assembly support system, According to JGJ130-2011, the stress and deformation of assembled support structure under various combined conditions of permanent load and construction load are analyzed. The results show that, The bearing capacity of prefabricated support structure under unfavorable load combination condition has enough safety reserve and can meet the requirements of code. Based on PLAXIS2D geotechnical finite element program, a numerical model of foundation pit considering soil-structure-groundwater interaction is established. This paper simulates the construction process of layered excavation and layered support of prefabricated structure supporting foundation pit. The influence of different single excavation depth on the maximum excavation depth of foundation pit is analyzed, and the following conclusions are obtained: in sandy soil and soft soil, With the increase of single excavation depth of foundation pit, the maximum excavation depth of foundation pit decreases in turn. In the clay soil, the cohesive force, the angle of internal friction and the stiffness parameter of soil have great influence on the maximum excavation depth of foundation pit. The single excavation depth of foundation pit has no obvious effect on the large excavation depth, but in the soft soil, the larger the excavation depth, the more the exposed goaf surface, and the smaller the stiffness of the soft soil is, the more deformation occurs. Therefore, the failure state of soil is easy to reach, which leads to the relatively small value of the maximum excavation depth of foundation pit in soft soil.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU753

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本文編號：1651290