Reason Analysis for the Difference between Measured and Calculated Self-weight Collapsibility of the Loess
-
摘要: 在兰州和平镇做了一大型现场浸水试验，测定了场地自重湿陷量，并利用实验数据计算了其湿陷量。现场浸水试验时，必须考虑浸水时间和入渗深度的影响，当湿润峰未到达湿陷性土层底面时，则存在很大一部分剩余湿陷量，由此低估了实际湿陷量。该现场浸水试验湿陷土层深度24 m，浸水61天，湿润峰深度达到12 m左右。按平均下渗速率估算，达到湿陷土层底面，需要120天以上。在湿陷性土层完全浸水的情况下，兰州地区大厚度湿陷性黄土的实测值远大于计算值，二者的比值为2.0左右，大于规范给出的修正系数1.5。综上所述，在现场试验时，除确定试验场地地貌单元、湿陷土层厚度外，必须给定合理的浸水时间，以便使湿陷性土层充分湿陷，或浸水后，及时测定湿润峰深度，计算实际湿陷土层的湿陷量，以便得出更合理的修正系数。Abstract: A large-scale field water immersion test has been carried out in Heping Town, Lanzhou, the self-weight collapsibility of the site has been measured in this paper, and the amount of collapsibility has been calculated by using the experimental data. The influence of immersion time and infiltration depth must be considered in the field water immersion test. When the wetting peak does not reach the bottom of collapsible soil, there will be a large part of residual collapsibility, which underestimates the actual amount of collapsibility. In this field immersion test, the depth of collapsible soil layer is 24m, the depth of wetting peak is about 12m, and the depth of wetting peak is about 12m. According to the estimation of average infiltration rate, it will take more than 120 days to reach the bottom of collapsible soil layer. Under the condition of full immersion of collapsible soil layer, the measured value of large thickness collapsible loess in Lanzhou area is much larger than the calculated value, and their ratio is about 2.0, which is greater than the correction coefficient of 1.5 given in the investigation specification. In conclusion, in the field immersion test, in addition to determining the landform unit of the test site and the thickness of the wet soil layer, a reasonable soaking time must be given in order to fully wet the collapsible soil layer. After flooding, the depth of wetting peak should be measured in time to calculate the actual collapsing amount of soil layer in order to obtain a more reasonable correction coefficient.
-
Keywords:
- soil mechanics /
- sandy loess /
- collapsibility /
- field water immersion /
- water content /
- Heping Town
-
-
中华人民共和国建设部. GB 50025-2004,湿陷性黄土地区建筑规范[S]. 北京:中国建筑工业出版社,2004. Ministry of Construction of the People's Republic of China. GB 50025-2004 Code for BuildingConstruction in Collapsible Loess Regions[S]. Bingjing:China Architecture and Building Press, 2004.
冯连昌,郑晏武.中国湿陷性黄土[M].中国铁道出版社,1982. FENG Lianchang, ZHENG Yanwu. Chinese collapsible loess[M]. China Railway Publishing House, 1982.
孙建中,王兰民,门玉明,等.黄土学(中篇)[M].西安:西安地图出版社,2013. SUN Jianzhong. WANG Lanmin, MEN Yuming,et al. Loess. Middle length. Loess geotechnical engineering[M]. Xi'an Cartographic Publishing House, 2013.
李大展,何颐华,隋国秀. Q2黄土大面积浸水试验研究[J].岩土工程学报,1993,15(2):111. LI Dazhan, HE Yihua SUI Guoxiu. Experimental study on large area soaking of Q2 Loess[J]. Journal of Geotechnical Engineering,1993,15(2):111.
李萍, 李同录, 王阿丹, 等. 黄土中水分迁移规律现场试验研究[J]. 岩土力学, 2013, 05:1331-1339. LI Ping, LI Tonglu, WANG Adan, et al. Field experimental study on water movement in Loess[J].Rock-soil Mechanics,2013.05:1331-1339.
罗宇生.宝鸡第二发电厂大面积试坑浸水试验报告[R]. 西安:西北电力设计院, 1994. LUO Yusheng. Experiment report on large area test pit in Baoji No.2 Power Plant[R]. Xi'an:North West Electric Power Design Institute,1994.
黄雪峰.大厚度自重湿陷性黄土的湿陷变形特征、地基处理方法和桩基承载性状研究[D]. 重庆:后勤工程学院, 2007. HUANG Xuefeng. Study on collapsibility deformation characteristics, foundation treatment methods and bearing behavior of pile foundation of large-thickness Self-Gravity Collapsible Loess[D]. Chongqing:School of Logistics Engineering,2007.
马侃彦,张继文,刘争宏,等.自重湿陷性黄土场地的试坑浸水试验[J].勘察科学技术,2009,(5):33-36. MA Kanyan, ZHANG Jiwen, LIU Zhenghong, el at. Pit immersion test of collapsible loess site with gravity[J]. Reconnaissance Science and Technology,2009,(5):33-36.
杨庆义.湿陷性黄土现场浸水试验研究[J].水电能源科学,2011,29(6):58-60. YANG Qingyi. Experimental study on in-situ soaking of collapsible loess[J]. Hydropower and Energy Science,2011,29(6):58-60.
王小军,米维军,熊治文,等.郑西客运专线黄土地基湿陷性现场浸水试验研究[J].铁道学报,2012,34(1):83-90. WANG Xiaojun, MI Weijun, XIONG Zhiwen, et al. Experimental study on collapsibility of loess foundation of Zhengxi passenger dedicated line in situ[J]. Journal of Railway,2012,34(1):83-90.
王延辉, 张希宏,袁勤刚.大厚度黄土自重湿陷性试验分析研究[J].勘察科学技术,2013,(3):5-8. WANG Yanhui, ZHANG Xihong, YUAN Qingang. Experimental analysis and study on collapsibility of loess with large thickness[J]. Reconnaissance Science and Technology,2013,(3):5-8.
武小鹏.基于试坑浸水试验的大厚度黄土湿陷及渗透特性研究[D]. 兰州:兰州大学, 2016. WU Xiaopeng. Study on collapsibility and permeability of loess with large thickness based on pit soaking test[D]. Lanzhou:Lanzhou University,2016.
杨生彬.兰州某工程黄土湿陷性室内与现场试验对比分析[A].第十五届全国工程物探与岩土工程测试学术大会论文集[C].2017:305-310. YANG Shengbin. Comparative analysis of loess collapsibility between laboratory and field test in Lanzhou project[A]. Proceedings of The 15th National Conference on Engineering Geophysical Exploration and Geotechnical Engineering Testing[C]. 2017:305-310.
邵生俊,李骏,李国良,等.大厚度湿陷性黄土隧道现场浸水试验研究[J]. 岩土工程学报,2018,40(8):1395-1404. SHAO Shengjun, LI Jun, LI Guoliang, et al. In-situ immersion test of collapsible loess tunnel with large thickness[J]. Journal of Geotechnical Engineering,2018,40(8):1395-1404.2017:305-310.
黄雪峰, 张广平, 姚志华, 等. 大厚度自重湿陷性黄土湿陷变形特性水分入渗规律及地基处理方法研究[J]. 岩土力学, 2011, 32(增刊2):100-108. HUANG Xuefeng, ZHANG Guangping, YAO Zhihua, et al. Research on deformation, permeability regularity and foundation treatment method of dead-weight collapse loess with heavy section[J]. Rock and Soil Mechanics, 2011, 32(Supp. 2):100-108.
姚志华,黄雪峰,陈正汉,等.兰州地区大厚度自重湿陷性黄土场地浸水试验综合观测研究[J]. 岩土工程学报,2012,34(1):65-74. YAO Zhihua, HUANG Xuefeng, CHEN Zhenghan, et al. Comprehensive observation and study on soaking test of heavy thickness collapsible loess site in Lanzhou area[J]. Journal of Geotechnical Engineering, 2012,34(1):65-74.
姚志华,黄雪峰,陈正汉,等.关于黄土湿陷性评价和剩余湿陷量的新认识[J]. 岩土力学,2014, 35(4):998-1006. YAO Zhihua, HUANG Xuefeng, CHEN Zhenghan, et al. A new understanding of the evaluation of loess collapsibility and the amount of residual collapsibility[J]. Rock-soil Mechanics,2014,35(4):998-1006.
XIE, W. L., LI, P., VANAPALLI, S. K., & Wang, J. D. (2018). Prediction of The Wetting-induced Collapse Behavior Using the Soil-water Characteristic Curve. Journal of Asian Earth Sciences, 151, 259-268. (in Portuguese)
PEREIRA, J. H., & FREDLUND, D. G. (2000). Volume change behavior of collapsible compacted gneiss soil. Journal of Geotechnical and Geo-environmental engineering, 126(10), 907-916.
计量
- 文章访问数: 1758
- HTML全文浏览量: 1
- PDF下载量: 1678
下载:
