【作者】 陈鹏飞；

【导师】 龚晓南；

【作者基本信息】 浙江大学 ， 岩土工程， 2020， 硕士

【摘要】 随着基坑深度的不断增加和周围环境的愈加复杂化,基坑的设计正在由稳定性控制的设计思路转向由变形控制的设计思路。本文首先对两个典型的有内支撑的基坑进行了现场监测,在此基础上建立了 PLAXIS模型并验证了模型的可靠性。然后把基坑的变形问题分为三个大的方面(土体、围护体系、水泥土加固)来进行分析,做了以下的工作:(1)基于PLAXIS3D中的土体硬化模型(HS),分析了多种参数对基坑围护墙的侧移和坑外土体沉降的影响。对各参数的敏感性进行了排序。(2)分析了围护墙的弹性模量、厚度、嵌固深度三个参数对基坑变形和受力的影响。发现围护墙的厚度对基坑变形的影响最为明显。(3)对内支撑在竖直方向的分布情况进行了优化,使得基坑的变形和受力更加合理。(4)对于在基坑主动区和被动区进行水泥土加固的情形进行了对比分析,得到在被动区加固的效果要远好于主动区加固效果的结论。在本文的工程条件下,被动区加固时,虽然变形受到了很大的约束,但是在基坑开挖面以下出现了方向相反并且不断增长的弯矩。说明基于本文模型的情况下,从受力方面考虑,被动区加固并非越宽越深就会越有利,需要对围护墙嵌固段的配筋进行加强设置。(5)对以上的计算结果进行了相对化处理,使得个参数的敏感性更加直观和更具可比性。更多还原

【Abstract】 As the depth of the excavation continues to increase and the surrounding environment becomes more and more complex,the design of f excavation is shifting from a design idea of stability control to a design idea of deformation control.In this paper,firstly,two typical excavations with internal support were monitored on site.On this basis,the PLAXIS model was established and the reliability of the model was verified.Then the deformation of the excavation was divided into three major aspects(soil,enclosure system,cement-soil reinforcement)for analysis,and the following work was doneBased on the soil hardening model(HS)in PLAXIS 3D,the effects of several parameters of soil on the lateral displacement of the retaining wall of the excavation and the settlement of the soil outside the pit are analyzed.The sensitivity of the 6 parameters is rankedThe influence of the elastic modulus,thickness and embedded depth of the retaining wall on the deformation and force of the excavation is analyzed.It is found that the thickness of the retaining wall has the most obvious influence on the deformation of the excavationThe distribution of internal supports in the vertical direction has been optimized to make the deformation and stress of the excavation more reasonable.A comparative analysis of the cement-soil reinforcement in the active area and the passive area of the excavation is carried out,and it is concluded that the reinforcement effect in the passive area is much better than the reinforcement effect in the active area And during the reinforcement of the passive zone,although the deformation is greatly restrained,the bending moment in the opposite direction and continuously increasing appears below the excavation surface of the foundation pit.It shows that from the perspective of stress,the wider and deeper the passive zone reinforcement is not,the more advantageous it is.It is necessary to strengthen the reinforcement of the embedded section of the retaining wallThe above calculation results are relativized,making the sensitivity of each parameter more intuitive and more comparable.更多还原