本文關(guān)鍵詞： 復(fù)合土釘墻支護 微型樁 變形 影響因素　出處：《西安建筑科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：復(fù)合土釘墻支護技術(shù)具有施工簡便、造價低廉和支護效果良好等顯著優(yōu)點而在深基坑工程中得到廣泛應(yīng)用。目前對該支護形式的作用機理研究較少,相應(yīng)理論也不夠完善,設(shè)計偏于保守,造成了巨大的資源浪費。為了使復(fù)合土釘墻支護技術(shù)更好的應(yīng)用于工程實踐,對其作深入的研究十分必要。本文以西安某深基坑工程為研究背景,對常見的深基坑工程支護方案進(jìn)行比較分析,采用微型樁+土釘?shù)膹?fù)合支護結(jié)構(gòu)。基于ABAQUS有限元軟件建立三維模型,模擬基坑開挖的全過程,模擬過程中考慮了土釘、微型樁和土體的粘結(jié)滑移作用,各構(gòu)件之間采用節(jié)點位移耦合的方法。通過與現(xiàn)場實測數(shù)據(jù)對比分析,驗證了ABAQUS模擬支護結(jié)構(gòu)的受力變化和基坑變形的合理性。通過合理的模型,分析歸納出土釘、微型樁和面層的參數(shù)對基坑變形的影響規(guī)律,找出最優(yōu)設(shè)計值并優(yōu)化原方案,為同類工程的設(shè)計和施工提供參考。本文的主要研究成果如下:(1)微型樁+土釘復(fù)合支護結(jié)構(gòu)在控制邊坡位移方面有顯著的效果。邊坡水平位移表現(xiàn)出頂部小,中部大的“鼓肚”型分布,并且下部有收斂趨勢。地表沉降最大值出現(xiàn)在離開挖面一定位置處,最后趨于穩(wěn)定;坑底隆起值距離開挖面越遠(yuǎn)越大,最后趨于穩(wěn)定。(2)從上至下,前二排土釘軸力呈現(xiàn)兩端小,中部較大的“棗核”型分布,從第三排土釘之后,最大軸力逐漸向開挖面移動且距離面層一定距離,其中土釘?shù)淖畲筝S力出現(xiàn)在第三排。第四排和第五排土釘軸力最大值出現(xiàn)在開挖面附近,說明此處坑壁坡腳剪應(yīng)力集中,容易發(fā)生事故。(3)基坑每步開挖支護后,微型樁出現(xiàn)的最大剪力均為負(fù)剪力,方向朝基坑的外側(cè)。隨著開挖步的進(jìn)行,對應(yīng)的最大剪力值也不斷增大,到了開挖底面位置,剪力的絕對值最大,在微型樁嵌入到坑底以下一定深度的時候,剪力值又變?yōu)?。(4)復(fù)合土釘墻支護結(jié)構(gòu)中,土釘?shù)牟贾梅绞�、長度、直徑、水平間距、傾角和微型樁的間距及面層的厚度是基坑變形的主要影響因素;微型樁的直徑和入土深度對控制基坑變形的效果不明顯。
[Abstract]:Composite soil nailing wall support technology has been widely used in deep foundation pit engineering because of its advantages such as simple construction, low cost and good support effect. The corresponding theory is not perfect, the design is conservative, resulting in a huge waste of resources. In order to make the composite soil nailing wall support technology better applied in engineering practice. It is necessary to make a deep research on it. This paper takes a deep foundation pit project in Xi'an as the research background to compare and analyze the common support schemes of deep foundation pit engineering. Using the composite support structure of micro-pile and soil nailing, a three-dimensional model based on ABAQUS finite element software is established to simulate the whole process of foundation pit excavation, and soil nailing is considered in the simulation process. The bond-slip effect of micro-pile and soil is analyzed by using the method of joint displacement coupling between the components. The results are compared with the field measured data. Through the reasonable model, the influence of soil nailing, micro-pile and surface layer parameters on foundation pit deformation is analyzed and concluded. Find out the optimal design value and optimize the original scheme. To provide reference for the design and construction of similar projects. The main research results of this paper are as follows: 1). The micro-pile soil nailing composite support structure has remarkable effect in controlling the slope displacement. The horizontal displacement of the slope is small at the top. There is a large "bulge" type distribution in the middle part, and the lower part is convergent. The maximum value of surface subsidence appears at a certain position from the excavated surface and tends to be stable at last. From top to bottom, the axial force of the first two rows of soil nailing shows the distribution of "jujube core" type with small ends and large middle part, after the third row of soil nailing. The maximum axial force gradually moves to the excavated surface and is far from the surface layer, in which the maximum axial force of soil nailing appears in the third row. The maximum axial force of 4th row and 5th row of soil nailing appears near the excavated surface. It shows that the shear stress concentration at the foot of the pit slope is easy to happen. 3) after every step of excavation of foundation pit, the maximum shear force of micro pile is negative shear force, which is oriented towards the outside of foundation pit. The corresponding maximum shear value is also increasing. At the bottom of the excavation, the absolute value of the shear force is the largest, when the micro-pile is embedded in a certain depth below the bottom of the pit. In the composite soil nailing wall support structure, the layout, length, diameter, horizontal spacing, inclination angle, spacing of the micro-pile and the thickness of the surface layer are the main influencing factors of foundation pit deformation. The effect of the diameter and depth of the micro pile on controlling the deformation of foundation pit is not obvious.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU753

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