摘要
现代气压沉箱工法以自动化挖排土、地面遥控操作区别于传统气压沉箱工法,在大深度、近距离地下工程建设中有着广泛的应用前景。针对气压沉箱特殊的施工工艺及流程,从现场监测和数值模拟,对上海某气压沉箱竖井施工对周边地层变形的影响进行研究。根据气压沉箱分节下沉特点,对其下沉过程进行力学分析,在仅考虑沉箱竖向受力平衡的前提下,提出用于分析施工全过程的周边地层变形力学模型,并介绍其有限元数值模拟的实现方法。土体采用Hardening-Soil弹塑性模型,可以模拟土体初次加载–卸载–再加载之间的刚度差异。通过对气压沉箱工程实例施工全过程的有限元数值模拟,结合现场监测数据,给出气压沉箱周边土体地面沉降和深层水平位移的分布形式及地表影响范围,同时也证实该力学模型及所采用土体参数的合理性和有效性。最后提出一个适合上海软土地区气压沉箱施工周边地表沉降计算模式,并与其他支撑开挖引起的地表沉降特征进行比较分析。
Characterized by unmanned excavation and remote controlling,the new pneumatic caisson（NPC） method has advantages in deep excavation such as deep shield tunnel shafts and some underground construction close to the existing structures or facilities. When adopted in urban areas,it is very important to control the ground deformation during a caisson construction. For this purpose,based on a shaft construction employing the NPC method in Shanghai,field measurement of ground deformation was conducted. Based on the particular construction sequence of pneumatic caisson,a kinematic mechanical model was proposed for evaluating the influence of NPC construction on the surrounding strata. This model was imbedded into a finite element method（FEM） program. In the numerical analysis,the soil was assumed as an elastoplastic material;and the Hardening-Soil（H-S） material model was applied. By comparing the FE predicted results using the proposed model and the field measurement,the accuracy and reliability of this model were verified;and the distribution pattern of soil movements induced by NPC construction was analyzed. It is found that its influence zone on the surface is about 1.5 times sinking depth of caisson. Finally,a ground surface settlement calculation mode during NPC construction in Shanghai soft ground is proposed and compared with that caused by other braced excavation methods.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2010年第A02期3941-3951,共11页
Chinese Journal of Rock Mechanics and Engineering
基金
"十一五"国家科技支撑计划资助项目(2006BAJ27B02–02)
教育部新世纪优秀人才支持计划基金项目(NCET–06–0378)
上海市重点学科建设项目(B308)
关键词
土力学
现代气压沉箱
隧道竖井
地层变形
现场监测
数值模拟
soil mechanics
new pneumatic caisson（NPC）
tunnel shaft
ground deformation
field measurement
numerical simulation
