本文選題：深基坑工程 + 斜拋撐��； 參考：《哈爾濱工業(yè)大學》2015年碩士論文

【摘要】：緊鄰既有建筑物地下室的深基坑工程越來越多,傳統(tǒng)的樁錨支護體系在深基坑施工空間上受到限制,而斜拋撐支護體系由于布置靈活,可以不受用地紅線、基坑周圍建(構)筑物的影響限制。另外,與整體內支撐結構相比,斜拋撐支護體系方便土方開挖,可以加快施工進度,縮短施工工期,并且造價低,可以節(jié)省大量的費用,具有明顯的經(jīng)濟效益。本文利用大型通用有限元軟件ABAQUS,針對支撐樁加承臺的斜拋撐支護體系,采用數(shù)值模擬的方法,對該斜拋撐支護體系在深大基坑中的應用進行研究。本文首先驗證了ABAQUS對深基坑建立數(shù)值模型的方法、步驟和手段是合理的,然后利用ABAQUS對支撐樁加承臺的斜拋撐在工程實例中的應用建立了數(shù)值模型,將數(shù)值模擬得到的支護樁向基坑內的水平位移和基坑外地表土體沉降分別與工程實測數(shù)據(jù)做對比,結果表明各個工況下的支護樁向基坑內的水平位移和坑外地表土體沉降與工程實測數(shù)據(jù)的曲線趨勢相近或一致。表明了該工程實例數(shù)值模擬的方法和結果是可行的,驗證了ABAQUS有限元軟件對支撐樁加承臺的斜拋撐支護基坑建立的數(shù)值模型方法和步驟是合理的。針對支撐樁加承臺的斜拋撐支護體系在第2章工程實際中的應用,本文利用ABAQUS有限元軟件重點分析了斜拋撐及承臺下兩個支撐樁的受力特點。并將斜拋撐與水平對撐作用下基坑變形進行對比,結果表明支撐樁加承臺的斜拋撐支護體系對抑制基坑底部土體隆起具有顯著的作用,但這種抑制基坑底部土體隆起的范圍是一定的(約為基坑底部距支護樁的水平距離23 m),超出了這一范圍,支撐樁加承臺的斜拋撐支護體系抑制基坑底部土體的隆起效果不明顯。結果還顯示,雖然斜拋撐支護體系作用下的支護樁向基坑內的水平位移和坑外地表土體沉降均大于水平對撐作用下相對應的值,但在斜拋撐支護體系的作用下,支護樁向基坑內的水平位移和坑外地表土體沉降均在基坑安全等級要求的警戒值和控制值內,該斜拋撐支護體系能夠保證基坑的安全。最后本文利用ABAQUS有限元軟件驗證了現(xiàn)行設計斜拋撐方法的合理性。本文利用ABAQUS有限元軟件進一步對該斜拋撐支護體系的幾何參數(shù)進行研究,主要進行了斜拋撐在承臺上不同支撐點位置、承臺下兩個支撐樁之間不同間距、斜拋撐與承臺和支護樁的不同連接(剛接和鉸接)形式、承臺下支撐樁的不同樁徑及在不同土體參數(shù)影響下的數(shù)值模擬。通過對比分析在斜拋撐支護體系的不同幾何參數(shù)影響下,坑外地表土體沉降、支護樁向基坑內的水平位移和坑內底部土體隆起及支護樁、承臺下支撐樁的受力特點,得出一些結論,為類似基坑工程項目的設計和施工提供有益的參考借鑒。
[Abstract]:There are more and more deep foundation pit projects close to the basement of existing buildings. The traditional pile-anchor support system is restricted in the construction space of deep foundation pit, while the inclined throwing bracing support system is not subject to the red line of land because of its flexible arrangement. The influence of construction around foundation pit is limited. In addition, compared with the whole internal support structure, the oblique brace support system is convenient for earthwork excavation, can speed up the construction progress, shorten the construction period, and the cost is low, which can save a lot of expenses and have obvious economic benefits. Based on Abaqus, a large scale finite element software, the application of this support system in deep and large foundation pit is studied by numerical simulation. In this paper, the method of establishing numerical model of deep foundation pit by Abaqus is verified, the steps and means are reasonable, and then the numerical model is established by using Abaqus for the application of inclined throwing brace of braced pile and pile cap in engineering example. The horizontal displacement of the supporting pile to the foundation pit and the settlement of the surface soil of the foundation pit obtained by numerical simulation are compared with the measured data of the project respectively. The results show that the horizontal displacement of the supporting pile and the settlement of the surface soil in the pit are similar or consistent with the measured data. It is shown that the numerical simulation method and results of the engineering example are feasible, and the numerical model method and steps of Abaqus finite element software for the foundation pit supported by supporting pile and pile cap are proved to be reasonable. In view of the application of inclined support system of supporting pile with pile cap in chapter 2 engineering practice, the stress characteristics of inclined throwing brace and two supporting piles under pile cap are analyzed in this paper by using Abaqus finite element software. The deformation of foundation pit under the action of oblique brace and horizontal bracing is compared. The results show that the supporting system of inclined throwing bracing with pile and pile cap plays a significant role in restraining the uplift of soil at the bottom of foundation pit. However, the range of restraining the soil uplift at the bottom of the foundation pit is certain (about 23 m / m) from the bottom of the foundation pit to the supporting pile, which is beyond this range, and the effect of the slanting supporting system with supporting pile and pile cap on restraining the uplift of the soil at the bottom of the foundation pit is not obvious. The results also show that, although the horizontal displacement of the supporting pile to the foundation pit and the settlement of the surface soil in the pit under the action of the inclined support system are larger than the corresponding values under the action of the horizontal bracing, but under the action of the slanting brace support system, The horizontal displacement of the supporting pile to the foundation pit and the settlement of the surface soil outside the pit are within the warning value and the control value required by the safety grade of the foundation pit, and the inclined support system can ensure the safety of the foundation pit. Finally, the rationality of the current design of skew support method is verified by Abaqus finite element software. In this paper, the geometric parameters of the inclined brace support system are further studied by using Abaqus finite element software. Different connections (rigid and hinged) of inclined brace with pile cap and supporting pile, numerical simulation of different pile diameter under pile cap and under different soil parameters. Under the influence of different geometric parameters of inclined support system, the settlement of surface soil, the horizontal displacement of supporting pile to foundation pit, the uplift of soil and supporting pile at the bottom of the pit, and the bearing characteristics of supporting pile under pile cap are analyzed. Some conclusions are obtained to provide useful reference for the design and construction of similar foundation pit projects.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU473

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