摘要
随着城市地下空间的快速发展,人工冻结法已经广泛应用于地铁联络通道的施工过程,但针对含盐粉砂层中的联络通道冻结法在地下水流作用下的机理尚不明确,导致原计划冻结时间的延长.以人工冻结法为研究背景,提出了冻结过程中水流-盐分共同作用下的耦合分析方法.首先,基于多孔介质传热、Darcy定律和Fick定律,建立了水-热-盐三场耦合的物理数学方程;然后,利用有限元软件COMSOL Multiphysics模拟含盐土体的冻结模型试验,并与模型试验结果进行对比分析,验证了本方法的有效性;最后,将本方法应用于南通地铁1号线永兴大道站|深南路站区间4#联络通道冻结法施工过程模拟,并相应开发了一套多物理场数据监测设备,将模拟结果与监测数据进行对比分析.结果表明,含盐土体比不含盐土体降温更慢,盐分浓度越大,降低同样温度所需时间越长;水头差导致冻结壁呈非对称状,上游冻结壁厚度小于下游冻结壁厚度;通过对冻结壁厚度和平均温度的计算,模拟冻结45 d达不到设计要求,需要冻结50 d.保证了南通地铁1号线联络通道人工冻结法施工的安全,并提供了一种在复杂环境条件下冻结施工的多场耦合分析方法.
Owing to the rapid development of urban underground space,the artificial freezing method has been widely used in the construction of subway-tunnel connecting channels.However,the mechanism of the freezing method as a joint result of water seep-age and saline soil remains unclear.Hence,the originally planned freezing time is extended.A multifield coupling analysis under the interaction of water seepage and salt in the freezing process is proposed.The No.4 connection channel between Yongxing Avenue Station and Shennan Road Station of the Nantong Urban Rail Transit Line 1 is the research object in this study.First,based on heat transfer theory,as well as water seepage and salt migration in porous media,the physical-mathematical equation of the water-thermal-salt coupling method is established.Second,thefinite element software COMSOL Multiphysics is used to simulate the freezing model test of saline soil mass,and the results of the model test are verified.Finally,the method above is applied to the construction simulation of the connecting-channel freezing method.A multiphysicalfield data monitoring equipment is designed,and the simulation and actual monitoring data are compared.The results show that the temperature of saline soil varies more slowly than that of non-saline soil.Ad-ditionally,a higher salt concentration in the soils implies a longer time required for their temperature to decrease to the same temperature.Moreover,the water head difference results in an asymmetrical frozen wall,and the thickness of the frozen wall upstream is smaller than that downstream.By calculating the thickness and average temperature of the frozen wall,it is discovered that the simulated freezing for 45 days does not satisfy the design requirements,and that the freezing time reaches 50 days.This study shows that safety is guaranteed when the freezing method is used in the connecting channel of Nantong Urban Rail Transit Line 1.The freezing method is a multifield coupling method that can be used under complex environmental condition
作者
李飞
王长虹
张海东
董济涵
LI Fei;WANG Changhong;ZHANG Haidong;DONG Jihan(School of Mechanics and Engineering Science,Shanghai University,Shanghai 200444,China)
出处
《上海大学学报（自然科学版）》
CAS
CSCD
北大核心
2023年第6期1090-1103,共14页
Journal of Shanghai University:Natural Science Edition
基金
上海高校特聘教授岗位计划资助项目(TP2018042)
上海市浦江人才计划资助项目(18PJ1403900)
上海市社会发展科技攻关资助项目(21DZ1204300)。
关键词
冻结法
多场耦合分析
盐分
渗流
监测
freezing technique
multifield coupling analysis
salt
water seepage
moni-toring
