【摘要】：盾構始發(fā)在隧道施工過程中占有的空間比重很小,卻是施工危險性最大的階段,其施工力學研究顯得尤為重要。本文以彈性力學和彈塑性理論為理論基礎,在總結大量研究經驗的基礎上,利用有限元軟件ABAQUS對盾構始發(fā)過程進行仿真模擬,并將模擬結果與實際案例的分析結果進行對比,驗證有限元模型計算結果的可靠性。通過構建模型并分析計算結果,研究得到土質強度、隧道間距、空間作用以及注漿壓力等參數(shù)與構筑物、圍巖位移和應力的變化關系。具體如下:(1)土質強度越大,其對抵抗地層擾動能力越強,引起地層損失越小。地表沉降、地層位移與應力、管片位移與應力隨著土質強度的增大而減小;在粉質粘土內,盾構擾動范圍隨著土質強度的增大而減小。(2)新建隧道對已建構筑物與圍巖的位移與應力變化影響較大。隧道間距越小,在新建隧道的影響下,管片位移與應力均發(fā)生改變,位移方向由指向兩側變?yōu)橄蜃?拱頂和仰拱呈增加趨勢,拱腰與之相反;在X軸和Y軸上,圍巖位移方向改變,在Z軸上,等位移線由“單駝峰”變?yōu)椤半p駝峰”形狀;拱頂圍巖地應力分布由“漏斗”變?yōu)椤半p漏斗”型;圍護結構受新建隧道的影響范圍主要分布在左側墻角處,洞口中心應力呈減小趨勢,洞口中心以下與之相反。(3)空間作用是構筑物不同部位應力分布迥異的主要因素。管片仰拱、拱頂呈受拉狀態(tài),拱腰呈受壓狀態(tài),前者應力值較大;陰陽角即墻角處應力值大于墻體中部。(4)注漿壓力設置過小,地層損失較大,地表沉降較為嚴重;設置過大引起地表大量隆起,通過模型計算結果與現(xiàn)場實際情況進行對比,得到膨脹系數(shù)合理值為1.E-04。通過比較實測與計算結果的管片收斂和地表沉降曲線的變化規(guī)律可知,計算模型能夠真實地反映現(xiàn)場的實際情況,計算結果可靠。
[Abstract]:The construction mechanics of shield tunneling is very important because it occupies a small proportion of the space in the tunnel construction process, but it is the most dangerous stage of construction. Based on the theory of elastic mechanics and elastic-plastic theory, this paper makes use of finite element software ABAQUS to simulate the starting process of shield tunneling, and compares the simulation results with the analysis results of actual cases. The reliability of the finite element model is verified. By constructing the model and analyzing the results, the relationship between soil strength, tunnel spacing, space action and grouting pressure on the structure, displacement and stress of surrounding rock is obtained. The main results are as follows: (1) the stronger the soil strength, the stronger the resistance to the formation disturbance and the smaller the formation loss. Ground subsidence, ground displacement and stress, segment displacement and stress decrease with the increase of soil strength; in silty clay, The disturbance range of shield machine decreases with the increase of soil strength. (2) the new tunnel has a great influence on the displacement and stress change of the built structure and surrounding rock. The smaller the tunnel spacing, the more the segment displacement and stress change, the direction of displacement changes from pointing to both sides to the left; the arch top and inverted arch show an increasing trend, the arch waist is the opposite; on the X axis and Y axis, The displacement direction of surrounding rock is changed from "single hump" to "double hump" on Z axis, and the distribution of earth stress in arch roof is changed from "funnel" to "double funnel". The influence range of the retaining structure by the new tunnel is mainly distributed in the corner of the left wall, the stress of the center of the hole is decreasing, and the stress below the center of the opening is opposite to it. (3) the spatial action is the main factor of the stress distribution in different parts of the structure. The stress value of the former is larger, the stress at the corner of the yin-yang angle is larger than that in the middle of the wall. (4) the grouting pressure is too small, the formation loss is large, and the surface subsidence is more serious. By comparing the results of model calculation with the actual situation in the field, the reasonable value of expansion coefficient is 1.E-04. By comparing the measured and calculated results of segment convergence and the variation of surface subsidence curve, it can be seen that the calculation model can truly reflect the actual situation in the field, and the calculation results are reliable.
【學位授予單位】：石家莊鐵道大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U455.43

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