武汉某异型深基坑支撑优化及阳角受力变形分析

发布时间：2019-06-07 14:50

【摘要】：城市建设的高速发展,对城市地下空间的利用率提出了更高的要求。超高层建筑、地铁工程、地下商场等工程日益增多,面临的工程技术问题也越来越复杂。深基坑工程作为一个复杂的岩土工程问题,日益引起专家学者的重视,已取得了很多成功的经验。目前,对于平面形状规则的基坑研究较多,已经形成了系统的分析方法和计算理论。然而,对于不规则形状基坑的研究相对较少,尤其是对于存在阳角的基坑的受力与变形研究更少。在建筑基坑监测规范中仅限于提出要重视基坑阳角处的受力与变形却并未给出阳角处受力及变形与其他部位的定量对比。因此,针对异型基坑存在的问题,主要从事如下几个方面的研究:(1)编制了基坑施工安全监控方案,进行了基坑开挖施工全过程安全监测。对基坑监测数据进行整理与分析,发现:①基坑大部分区域变形已超过预警值,应对基坑支撑方式进行优化;②基坑阳角处变形明显大于其他部位,需对阳角处应力及变形规律进行研究。(2)通过分析多种支护结构受力及变形计算方法,提出采用增量法对支护结构受力及变形进行计算更符合工程实际。在此基础上,采用FLAC3D有限差分程序建立三维基坑模型,根据基坑实际开挖情况划分基坑工况,将不同工况下围护墙侧向变形数据与实际监测数据进行了对比,表明两者吻合性较好,从而验证了数值分析模型的合理性。(3)通过对比不同工况围护墙侧向变形,找出导致围护墙变形增幅最大的工况,进而确定关键开挖步;通过对比三种支撑形式下围护墙的侧向变形及支撑轴力,指出阳角北侧施加一道支撑的方式各个支撑受力较均匀,支撑能够充分发挥作用,控制围护墙侧向变形效果最好。(4)在不改变基坑支撑方式条件下,通过改变基坑阳角角度,研究不同角度阳角角部空间应力与变形及支撑轴力的变化规律,指出随着阳角角度的增大,阴角及其南侧区域变形减小,且减小幅度最大位置在阴角附近,阳角及其以北区域位移增大,且增幅最大位置在阳角处;当阳角角度为145°时,阳角处应力集中最明显,当阳角角度大于150°时,应力集中现象逐渐消失。
[Abstract]:With the rapid development of urban construction, the utilization rate of urban underground space is put forward higher requirements. There are more and more projects such as super high-rise buildings, subway projects, underground shopping malls and so on, and the engineering and technical problems are becoming more and more complex. As a complex geotechnical engineering problem, deep foundation pit engineering has attracted more and more attention of experts and scholars, and has achieved a lot of successful experience. At present, there are many studies on the foundation pit with regular plane shape, and a systematic analysis method and calculation theory have been formed. However, there is relatively little research on the irregular shape foundation pit, especially on the stress and deformation of the foundation pit with positive angle. In the monitoring code of building foundation pit, it is limited to pay attention to the force and deformation at the positive angle of the foundation pit, but the quantitative comparison between the force and deformation at the positive angle and other parts is not given. Therefore, in view of the problems existing in the special-shaped foundation pit, the main research is as follows: (1) the safety monitoring scheme of foundation pit construction is compiled, and the safety monitoring of the whole process of foundation pit excavation construction is carried out. The monitoring data of foundation pit are sorted out and analyzed, and it is found that: (1) the deformation of most areas of foundation pit has exceeded the early warning value, so the supporting mode of foundation pit should be optimized; (2) the deformation at the positive angle of foundation pit is obviously larger than that at other parts, so it is necessary to study the stress and deformation law at the positive angle. (2) by analyzing various calculation methods of stress and deformation of supporting structure, It is proposed that the incremental method is more in line with the engineering practice to calculate the stress and deformation of the supporting structure. On this basis, the three-dimensional foundation pit model is established by FLAC3D finite difference program, and the foundation pit working conditions are divided according to the actual excavation conditions of the foundation pit, and the lateral deformation data of the retaining wall under different working conditions are compared with the actual monitoring data. The results show that the two are in good agreement with each other, which verifies the rationality of the numerical analysis model. (3) by comparing the lateral deformation of the retaining wall under different working conditions, the working conditions that lead to the largest increase in the deformation of the retaining wall are found out, and then the key excavation steps are determined. By comparing the lateral deformation and supporting axial force of the retaining wall under the three supporting forms, it is pointed out that the support force of each support on the north side of the positive angle is more uniform, and the support can give full play to its function. The effect of controlling the lateral deformation of the retaining wall is the best. (4) under the condition of not changing the supporting mode of the foundation pit, the spatial stress, deformation and supporting axial force of the angle of the positive angle of the foundation pit are studied by changing the angle of the positive angle of the foundation pit. It is pointed out that with the increase of the angle of positive angle, the deformation of the angle of yin and its south side decreases, and the maximum amplitude of decrease is near the angle of yin, and the displacement of the angle of yang and its north increases, and the position of the largest increase is at the angle of yang. When the positive angle is 145 掳, the stress concentration at the positive angle is the most obvious, and when the positive angle is more than 150 掳, the stress concentration phenomenon disappears gradually.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU753

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