本文關(guān)鍵詞： 軟土深基坑 咬合樁圍護(hù)結(jié)構(gòu) 基坑變形 現(xiàn)場(chǎng)監(jiān)測(cè) FLAC數(shù)值模擬　出處：《成都理工大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：目前,地鐵建設(shè)特別是地鐵車站建設(shè)絕大多數(shù)都選擇基坑開挖并結(jié)合支護(hù)體系的方法。地鐵基坑深度較深,且多處于城市建筑和管線密集地帶,因此對(duì)其設(shè)計(jì)、施工的安全可靠性提出更嚴(yán)格要求。深基坑在施工狀態(tài)下風(fēng)險(xiǎn)較大,需要通過施加支護(hù)措施確�；邮┕さ陌踩�。隨著基坑技術(shù)越來越成熟,在不同地質(zhì)條件下,深基坑的支護(hù)方式也隨之越來越多樣化。咬合樁基坑圍護(hù)結(jié)構(gòu)結(jié)合了地下連續(xù)墻和普通鉆孔樁各自的優(yōu)勢(shì),具有較強(qiáng)的適用價(jià)值,但國(guó)內(nèi)對(duì)于咬合樁方面的研究尚且不足,需要大量的試驗(yàn)和工程應(yīng)用對(duì)其適用性進(jìn)行研究,本文通過研究軟土深基坑咬合樁圍護(hù)結(jié)構(gòu)在施工階段的受力及變形特性,為以后同類型的基坑工程提供參考。本文闡述了軟土深基坑咬合樁圍護(hù)結(jié)構(gòu)的變形理論,并結(jié)合南京新莊地鐵車站深基坑的現(xiàn)場(chǎng)監(jiān)控?cái)?shù)據(jù)以及對(duì)該基坑的有限元分析結(jié)果進(jìn)行了如下分析:(1)對(duì)軟土深基坑的受力性能和變形機(jī)理進(jìn)行了理論分析,對(duì)咬合樁的受力機(jī)理和設(shè)計(jì)方法進(jìn)行研究,對(duì)軟土深基坑的變形影響因素進(jìn)行了分析;(2)分析了新莊站基坑監(jiān)測(cè)方案,并對(duì)咬合樁圍護(hù)結(jié)構(gòu)水平變形、支撐軸力和周邊地表沉降的監(jiān)測(cè)數(shù)據(jù)進(jìn)行整理,得出咬合樁圍護(hù)結(jié)構(gòu)體系在軟土地層施工階段的變形量和變形規(guī)律與土層中淤泥質(zhì)層的關(guān)系,淤泥質(zhì)層較厚的區(qū)域樁體變形相對(duì)較大,圍護(hù)樁處于淤泥質(zhì)層的部分可能樁體變形速率大,甚至出現(xiàn)部分隆起。因?yàn)橛倌噘|(zhì)軟土的蠕變性,基坑封底后圍護(hù)體仍然會(huì)有持續(xù)較大變形,而淤泥質(zhì)層較薄或不含淤泥質(zhì)層的區(qū)域圍護(hù)結(jié)構(gòu)變形較小,且基坑封底后變形速率快速收斂;(3)利用有限差分析軟件FLAC3D對(duì)基坑開挖過程中咬合樁體的受力和變形、支撐軸力及周邊地表沉降進(jìn)行數(shù)值模擬分析,并將模擬所得結(jié)果與現(xiàn)場(chǎng)監(jiān)測(cè)數(shù)據(jù)作對(duì)比分析得出數(shù)值模擬結(jié)果與監(jiān)測(cè)數(shù)據(jù)基本相符,證明數(shù)值模擬軟件研究軟土基坑咬合樁圍護(hù)結(jié)構(gòu)的變形特性具有準(zhǔn)確性和適用性,通過最大主應(yīng)力圖找到基坑圍護(hù)結(jié)構(gòu)安全最不利的位置,并且發(fā)現(xiàn)在咬合樁圍護(hù)結(jié)構(gòu)中,鋼筋混凝土樁(葷樁)承擔(dān)了大部分的抵抗土壓力的作用;(4)通過數(shù)值模擬分析不同巖土體物理力學(xué)參數(shù)和設(shè)計(jì)參數(shù)對(duì)于軟土深基坑咬合樁圍護(hù)結(jié)構(gòu)性能的影響,并且就這些參數(shù)對(duì)圍護(hù)結(jié)構(gòu)變形的影響程度進(jìn)行了分析,結(jié)果表明土體彈性模量、內(nèi)摩擦角以及素混凝土樁混凝土強(qiáng)度等級(jí)變化對(duì)基坑圍護(hù)結(jié)構(gòu)變形及周邊土體沉降影響較大,粘聚力、樁長(zhǎng)及咬合量的影響則相對(duì)較小,為該基坑設(shè)計(jì)、施工提出優(yōu)化方案,為之后同類型的深基坑設(shè)計(jì)和施工提供參考意見。
[Abstract]:At present, most subway construction, especially subway station construction, choose the method of foundation pit excavation and combined with supporting system. The subway foundation pit is deep in depth, and most of it is located in urban buildings and pipeline dense ground zone, so it is designed. The safety and reliability of the construction is more strictly required. The deep foundation pit is riskier in the construction state, so it is necessary to apply supporting measures to ensure the safety of the foundation pit construction. As the foundation pit technology becomes more and more mature, under different geological conditions, The retaining methods of deep foundation pit are more and more diversified. The retaining structure of bite pile foundation pit combines the advantages of underground continuous wall and common bored pile, and has strong applicable value, but the research on bite pile in China is still insufficient. A large number of tests and engineering applications are needed to study its applicability. In this paper, the stress and deformation characteristics of the retaining structure of occluded pile in soft soil deep foundation pit during the construction stage are studied. In this paper, the deformation theory of entrainment pile retaining structure of deep foundation pit in soft soil is expounded. Combined with the field monitoring data of the deep foundation pit of Nanjing Xinzhuang subway station and the result of finite element analysis of the foundation pit, this paper makes a theoretical analysis on the mechanical behavior and deformation mechanism of the deep foundation pit in soft soil. The stress mechanism and design method of the occlusal pile are studied. The influencing factors of the deformation of the soft soil deep foundation pit are analyzed. (2) the monitoring scheme of the foundation pit of Xinzhuang station is analyzed, and the horizontal deformation of the retaining structure of the occlusal pile is analyzed. The monitoring data of supporting axial force and surrounding surface settlement are sorted out, and the relationship between the deformation amount and deformation law and the silt layer in the soil layer during the construction phase of the masonry retaining structure system of the occlusal pile is obtained. The pile deformation in the area with thicker silt layer is relatively large, and the pile deformation rate may be high or even some uplift may occur when the retaining pile is located in the silt layer, because of the creep property of the silt soft soil, After the foundation pit is sealed, there will still be large deformation of the retaining body, while the deformation of the surrounding structure in the area without silt layer is smaller than that in the silt layer. And the deformation rate of foundation pit is convergent rapidly after foundation pit sealing. The finite difference analysis software FLAC3D is used to simulate the force and deformation of the entrainment pile during excavation, the supporting axial force and the surface settlement around the foundation pit. By comparing the simulation results with the monitoring data, the numerical simulation results are in good agreement with the monitoring data, which proves that the numerical simulation software is accurate and applicable to study the deformation characteristics of the retaining structure of the entrainment pile in soft soil foundation pit. Through the maximum principal stress diagram to find out the most unfavorable position of the foundation pit enclosure structure, and found that in the occluded pile enclosure structure, Reinforced concrete pile (pile) bears most of the function of resisting earth pressure. Through numerical simulation, the influence of physical and mechanical parameters and design parameters of different rock and soil mass on the performance of retaining structure of occluded pile in deep foundation pit of soft soil is analyzed. The influence of these parameters on the deformation of retaining structure is analyzed. The results show that the elastic modulus of soil, the angle of internal friction and the change of concrete strength grade of plain concrete pile have great influence on the deformation of foundation pit retaining structure and the settlement of surrounding soil. The influence of cohesion, pile length and bite amount is relatively small. The optimization scheme for the design and construction of the foundation pit is put forward, and the reference for the design and construction of the same type of deep foundation pit is provided.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TU753

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