王锋,刘德仁,程富强,等. 深厚黄土场地浸水试验及湿陷性评价[J]. 水利水运工程学报,2023(5):131-138. doi: 10.12170/20220411003
引用本文: 王锋,刘德仁,程富强,等. 深厚黄土场地浸水试验及湿陷性评价[J]. 水利水运工程学报,2023(5):131-138. doi: 10.12170/20220411003
(WANG Feng, LIU Deren, CHENG Fuqiang, et al. Immersion test and collapsibility evaluation of deep loess site[J]. Hydro-Science and Engineering, 2023(5): 131-138. (in Chinese)). doi: 10.12170/20220411003
Citation: (WANG Feng, LIU Deren, CHENG Fuqiang, et al. Immersion test and collapsibility evaluation of deep loess site[J]. Hydro-Science and Engineering, 2023(5): 131-138. (in Chinese)). doi: 10.12170/20220411003

深厚黄土场地浸水试验及湿陷性评价

Immersion test and collapsibility evaluation of deep loess site

  • 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。研究结果表明: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,湿润锋面到达测点的时间越来越滞后;地表沉降经历缓慢-快速-减缓-稳定的过程,沉降速率可达5.88 cm/d,浸水50 d时完成总沉降量的60%;该场地0~16.5 m强湿陷土层的湿陷量占湿陷总量80%以上;试坑周围有大量环向裂缝发育,裂缝最宽为34 cm,错台高度可达50 cm;结合室内和现场试验结果,该场地的自重湿陷下限深度和地基处理深度可取24.0 m。研究结果可为深厚湿陷性黄土地区的工程建设提供参考。

     

    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 test and analyze 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 5.88 cm/d. 60% of the total subsidence is completed among 50 d. The depth range of 0~16.5 m is the soil layer with strong subsidence, and 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 34 cm and the height of stage-off up to 50 cm. Based on the laboratory and field tests, 24 m can be used as the lower limit of gravity collapsibility depth and foundation treatment depth of the site. The research results can provide a reference for engineering construction in deep collapsible loess area.

     

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