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  本文選題：復合土釘墻　切入點：變形　出處：《西南交通大學》2017年碩士論文

【摘要】：土釘+預應力錨索+攪拌樁復合基坑支護結構在工程中得到了廣泛應用,但是現階段關于該結構工作特性的研究成果還較少,導致理論明顯滯后于工程實踐。針對這一現狀,本文結合工程實例,采用 Midas/GTS(Geotechnical and Tunnel Analysis System)有限元分析程序對該類型復合土釘支護結構的工作性狀進行了詳細分析,得到的研究成果及結論如下:1.通過對基坑變形的監(jiān)測數據與Midas/GTS有限元程序計算結果比較分析,結果表明,該有限元程序能較好地模擬基坑的工作性狀。2.加入攪拌樁后,支護結構的受力變形性狀發(fā)生了明顯變化,復合結構的變形形態(tài)與樁錨式支護結構相似,其側向變形呈中間大、上下兩端較小的變化規(guī)律,且最大值約在0.75倍開挖深度處,土釘的軸力呈沿長度方向遞減的變化趨勢。3.按照軸力的不同分布形態(tài),可以將土釘分為軸力遞增型、弓形及軸力遞減型三種。軸力遞增型土釘主要分布在基坑的上部,其軸力沿土釘長度方向遞增;軸力呈弓形的土釘主要分布在基坑的中部,其軸力為中間最大,兩端較小;軸力遞減型土釘主要分布在基坑的下部,其軸力在土釘與攪拌樁接觸的部位最大,往后逐漸減小。4.施加預應力能有效控制基坑的側向變形,且預應力施加在基坑的側向變形最大值對應的部位時,對變形的限制效果最好。5.在基坑的穩(wěn)定性計算中,其穩(wěn)定性系數取基坑強度折減計算不收斂對應的強度折減系數存在不合理之處,取基坑強度折減系數與側向變形關系曲線中拐點對應的折減系數作為基坑的穩(wěn)定性系數更為合理。6.影響支護結構穩(wěn)定性的因素包括土釘的長度、坑底超挖深度、攪拌樁的直徑及嵌固深度等,其中,基坑下部土釘的長度是影響基坑穩(wěn)定性的關鍵因素。
[Abstract]:Soil nailing prestressed anchor cable mixing pile composite foundation pit support structure has been widely used in engineering, but at present, there are few research results on the working characteristics of the structure, which leads to the theory obviously lagging behind the engineering practice. In this paper, the working behavior of this type of composite soil nailing support structure is analyzed in detail by using Midas/GTS(Geotechnical and Tunnel Analysis system finite element analysis program combined with an engineering example. The research results and conclusions are as follows: 1.Through comparing the monitoring data of foundation pit deformation with the results of Midas/GTS finite element program, the results show that the finite element program can simulate the working behavior of foundation pit. The deformation behavior of the supporting structure has changed obviously. The deformation pattern of the composite structure is similar to that of the pile-anchor support structure. The lateral deformation of the composite structure is large in the middle, the upper and lower ends are smaller, and the maximum value is about 0.75 times of the excavation depth. The axial force of soil nailing tends to decrease in the direction of length. According to the different distribution form of axial force, the soil nailing can be divided into three types: axial force increasing type, arch type and axial force decreasing type. The axial force increasing type soil nailing mainly distributes in the upper part of foundation pit. The axial force increases gradually along the length of the soil nailing, the axial force of the soil nailing with bow shape is mainly distributed in the middle of the foundation pit, the axial force is the largest in the middle and the two ends are small, and the decreasing axial force is mainly distributed in the lower part of the foundation pit. The axial force is the largest in the contact part between soil nailing and mixing pile, and then gradually decreases .4.When the application of prestress can effectively control the lateral deformation of foundation pit, and the prestress is applied to the position corresponding to the maximum lateral deformation of foundation pit, In the calculation of the stability of foundation pit, the stability coefficient is taken from the strength reduction calculation of foundation pit, and the strength reduction coefficient corresponding to the convergence of the strength reduction calculation of foundation pit is unreasonable. It is more reasonable to take the reduction coefficient corresponding to the inflexion point in the curve of strength reduction and lateral deformation of foundation pit as the stability coefficient of foundation pit. The factors affecting the stability of supporting structure include the length of soil nailing, the depth of overdigging at the bottom of the pit. Among them, the length of soil nailing at the bottom of the foundation pit is the key factor affecting the stability of the foundation pit.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU753

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本文編號：1653885