基于周边建筑物变形控制的深基坑分区支护数值模拟

发布时间：2018-11-26 17:01

【摘要】：深基坑土体的开挖,改变了周围土体的受力状态,坑底及侧壁的土体发生位移。这些变形可能最终导致临近建筑物发生被动的变形,从而影响其正常使用,甚至破坏。根据石家庄某一空间尺寸的深基坑,初步选择桩锚索支护结构;采用有限差分法分析基坑支护体系与周围建筑物的相互影响;在此基础上对基坑进行分区支护设计。(1)对基坑坡壁外侧没有建筑物情况进行数值模拟,分析坡壁土体水平位移及沉降,结果表明:离90度平面阴角端部,0.22倍坡壁长度或2.8倍基坑深度范围内,坡壁土体变形明显受到另一条坡壁的约束;而其它范围坡壁的变形受到的空间效应很小,可以按照平面应变理论进行分析。(2)平面为矩形、长边平行于基坑坡壁的建筑物,在紧邻坡壁的中间位置时,随着其基础外侧边线离坡壁距离的增加,建筑物地基沉降、基坑坡壁变形逐渐减小。相对于没有建筑物的情况,建筑物的存在增大了坡壁中间一定范围土体的变形;当基坑平面阴角为90度时,该范围是1.85倍坡壁方向建筑物的边长,或0.57倍的坡壁边长。当建筑物基础外侧边线离坡壁距离大于1.5倍基坑深度时,可以不考虑建筑物对坡壁变形、土体开挖对建筑物的影响。(3)建筑物在坡壁靠近90度平面阴角时,相对于无建筑物的情况,坡壁土体位移主要增大范围是:离角部1.49倍坡壁方向建筑物边长,或0.46倍坡壁长度内。建筑物在基坑坡壁角部,相对于坡壁中间位置的情况,坡壁水平位移及地表沉降的增加量要小。(4)根据周围环境变形、坡壁稳定的要求,对基坑进行分区支护。当建筑物在相对于东侧坡壁的中间位置,且其基础外侧边线离东侧坡壁为0.5倍坑深时,可以通过增加东侧坡壁中间、1.85倍坡壁方向建筑物边长范围内支护结构的刚度,控制建筑物地基的沉降量、沉降差。凭借减弱西侧坡壁空间效应明显的角部范围支护刚度,能够降低坡壁外侧地下管线的差异变形。
[Abstract]:The excavation of deep foundation pit soil changes the stress state of surrounding soil and the displacement of soil in bottom and sidewall. These deformations may eventually lead to passive deformation of adjacent buildings, which may affect their normal use or even damage. According to a space size deep foundation pit in Shijiazhuang, the support structure of pile and anchor cable is preliminarily selected, and the interaction between supporting system of foundation pit and surrounding buildings is analyzed by finite difference method. On the basis of this, the zonal support design of foundation pit is carried out. (1) numerical simulation is carried out on the condition that there is no building outside the slope wall of the foundation pit, and the horizontal displacement and settlement of the slope wall soil are analyzed. The results show that the end of the negative angle is 90 degrees from the plane. In the range of 0.22 times the length of the slope wall or 2.8 times the depth of the foundation pit, the deformation of the slope wall soil is obviously constrained by another slope wall. However, the spatial effect on the deformation of other slope walls is very small, which can be analyzed according to the plane strain theory. (2) buildings with rectangular plane and long edges parallel to the slope wall of foundation pit are located in the middle of the slope wall. With the increase of the distance from the lateral side of the foundation to the slope wall, the foundation settlement of the building and the deformation of the foundation pit wall gradually decrease. Compared with the case of no building, the existence of the building increases the deformation of soil in a certain range in the middle of the slope wall, and when the plane angle of foundation pit is 90 degrees, the range is 1.85 times the side length of the building in the direction of the slope wall, or 0.57 times the side length of the slope wall. When the distance from the outside side of the building foundation to the slope wall is more than 1.5 times the depth of the foundation pit, the deformation of the slope wall and the influence of soil excavation on the building can be ignored. (3) when the slope wall is close to 90 degree plane negative angle, Compared with the case without building, the main increase range of the soil displacement of the slope wall is 1.49 times from the angle of the slope wall direction, or 0.46 times the length of the slope wall. Compared with the middle position of the slope wall, the increase of horizontal displacement and surface subsidence of the slope wall in the corner of the foundation pit wall is small. (4) according to the requirements of the surrounding environment and the stability of the slope wall, the foundation pit is supported by subdivision. When the building is in the middle position relative to the east slope wall, and the lateral side line of the foundation is 0.5 times deeper than the eastern slope wall, the stiffness of the support structure can be increased in the middle of the east slope wall and 1.85 times the length of the building side. Control the settlement of the building foundation, the settlement is poor. The differential deformation of the underground pipeline outside the slope wall can be reduced by reducing the angular range support stiffness of the west slope wall.
【学位授予单位】：河北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU753

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