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兰州新区深厚黄土场地浸水试验及湿陷性评价研究
王锋1, 刘德仁2, 程富强3, 霍源4, 白之璋4, 徐硕昌2
1.甘肃铁路投资建设集团有限公司;2.兰州交通大学;3.中铁第五勘察设计院集团有限公司;4.中兰铁路客运专线有限公司
摘要:
现场浸水试验是研究深厚黄土场地自重湿陷特征、评价其湿陷性的重要手段。基于原状黄土的室内试验,在兰州新区深厚黄土场地开展现场浸水试验,测试分析浸水过程中的土层含水率及地基沉降变形发展规律,并对该深厚黄土场地的自重湿陷特性进行讨论得到:兰州新区原状黄土的含水率和干密度沿深度逐渐增大,孔隙比、自重湿陷系数大幅降低;随着水分入渗深度增加,体积含水率变化曲线上翘时间依次增大,湿润锋面达到测点的时间越来越滞后;地表沉降经历缓慢-快速-减缓-稳定过程,沉降速率可达5.88cm/d,浸水50d时完成总沉降量的60%;该场地0~16.5m深度范围为强湿陷土层,其湿陷量占整个场地的80%以上;试坑周围有大量环向裂缝发育,裂缝最宽为34cm,错台高度可达50cm;结合室内和现场试验结果,可将24m作为该场地的自重湿陷下限深度和地基处理深度。
关键词:  兰州新区  自重湿陷系数  深厚黄土场地  现场浸水试验  湿陷性评
DOI:
分类号:TU444
基金项目:甘肃省基础研究创新群体项目(21JR7RA347)
Study on Immersion Test and Collapsible Evaluation of Deep Loess Site in LanZhou New District
WANG Feng1, LIU De-ren2, CHENG Fu-qiang3, HUO Yuan4, BAI Zhi-zhang4, XU Shuo-chang2
1.China Gansu Railway Construction Investment Group Co Ltd,Lanzhou;2.Lanzhou Jiaotong University,Lanzhou;3.China Railway Fifth Survey And Design Institute Group Co. Ltd;4.Zhongwei to Lanzhou railway Passenger Dedicated Line Co Ltd,Baiyin
Abstract:
Field immersion test is an important means to study the characteristics of self-gravity collapsibility of deep loess site and evaluate its collapsibility. Based on physical and mechanical parameter tests of undisturbed loess, field immersion test was carried out in deep loess site in Lanzhou New District to tests and analyzes the development law of water content of soil layer and foundation settlement deformation, study the self-weight collapsible characteristics of the deep loess site, and evaluate the self- gravity collapsible subsidence of this deep loess site. Researches show that the moisture content and dry density of the undisturbed loess in Lanzhou New District increase gradually with the depth, but the porosity ratio and gravity collapsibility coefficient decrease greatly. With the increasing of water infiltration depth, the growth time of volumetric water content curve increases successively, and the time of wetting front reaching the measuring point lags more and more. The surface subsidence experiences a slow-fast-slow down-steady process, and the subsidence rate can reach 5.88cm/d. 60% of the total subsidence is completed among 50d. The depth range of 0~16.5m is the soil layer with strong subsidence, its subsidence accounts for more than 80% of the whole site. A large number of circumferential fractures developed around the test pit, with the widest width of 34cm and the height of stage-off up to 50cm Combined with the results of laboratory and field tests, 24m can be used as the lower limit of gravity collapsibility depth and foundation treatment depth of the site.
Key words:  Lanzhou New District  self-gravity collapsible coefficient  deep loess site  field immersion test  collapsible evaluation
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