1. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, China; 2. Highway and Railway Research Institute, Hohai University, Nanjing 210098; 3. Geotechnical Research Institute, Hohai University, Nanjing 210098; 4. Hongkong Polytechnic University, H K, China
Abstract:It is more realistic that the clay unit cell of road embankment is in the state of plane strain. The creep characteristics of over-consolidated soils are studied through plane strain tests for the undisturbed soft clay. Four creep tests are carried out by using the plane strain creep apparatus, one is conducted on normally consolidated clay and three are on over-consolidated clay. The studies show that for the normally consolidated soils, the volumetric strain of creep in plane strain tests varies in the same way with the secondary consolidation under one-dimension condition, and that the clay presents less axial strain in plane strain tests than that in one-dimension tests when the principal stress ratio equals the ratio in K0 state. The definition of plane strain over-consolidation ratio (OCRp) is given, and it is used to describe the characteristics of over-consolidated soils. It is found that it is reasonable to determine the volumetric creep coefficient as well as axial creep coefficient directly by using OCRp. Compared with normally consolidated clay, under plane strain state, the over-consolidated clay has a lager Poisson's ratio and larger principal stress in the direction of limited deformation.
[1] 赵维炳, 刘国楠, 李荣强. 控制工后变形新一代软基处理技术的发展[J]. 土木工程学报, 2004, 37(6): 79-819. (ZHAO Wei-bin, LIU Guo-nan, LI Rong-qiang. Development of new improving techniques for controlling post-construction deformation of soft soil ground[J]. China Civil Engineering Journal, 2004, 37(6): 79-819. (in Chinese)) [2] KUTTER B L, SATHIALING N. Elastic-viscoplastic modeling of the rate-dependent behavior of clays. Géotechnique, 1992, 42(3): 427-441. [3] 詹美礼, 钱家欢, 陈绪禄. 软土流变特性试验及流变模型[J]. 岩土工程学报, 1993, 15(3): 55-62. (ZHAN Mei-li, QIAN Jia-huan, CHEN Xu-lu. Tests on rheological behavior of soft soil and rheologic model[J]. Chinese Journal of Geotechnical Engineering, 1993, 15(3): 55-62. (in Chinese)) [4] YIN J H, ZHU J G, GRAHAM J. A new elastic viscoplastic model for time-dependent behavior of normally and over consolidated clays: theory and verification[J]. Canadian Geotechnical Journal, 2002, 39(1): 157-173. [5] BORJA R I, KAVAZANJIAN E. A constitutive model for the stress-strain-time behavior of ‘wet’ clays[J]. Géotechnique, 1985, 35(3): 283-298. [6] 李军世, 孙 钧. 上海淤泥质黏土的Mesri蠕变模型[J]. 土木工程学报, 2001, 34(6): 75-79. (LI Jun-shi, SUN Jun. Mesri creep model of Shanghai soft clay[J]. China Civil Engineering Journal, 2001, 34(6): 75-79. (in Chinese)) [7] 王常明, 王 清, 张淑华. 滨海软蠕变特性及蠕变模型[J]. 岩石力学与工程学报, 2004, 23(3): 227-230. (WANG Chang-ming, WANG Qing, ZHANG Shu-hua. Creep characteristics and creep model for marine soft soils[J]. Chinese Journal of Rock Mechanics and Engineering, 2003, 23(3): 227-230. (in Chinese)) [8] 陈晓平, 周秋娟, 朱鸿鹄, 等. 软土蠕变固结特性研究[J]. 岩土力学, 2007, 28(增刊): 1-9. (CHEN Xiao-ping, ZHOU Qiu-juan, ZHU Hong-hu, et al. Research on creep and consolidation characteristics of soft soil[J]. Rock and Soil Mechanics, 2007, 28(S0): 1-9. (in Chinese)) [9] 朱鸿鹄, 陈晓平, 程小俊, 等. 考虑排水条件的软土蠕变特性及模型研究[J]. 岩土力学, 2006, 27(5): 694-698. (ZHU Hong-hu, CHEN Xiao-ping, CHEN Xiao-jun, et al. Study on creep characteristics and model of soft soil considering drainage condition[J]. Rock and Soil Mechanics, 2006, 27(5): 694-698. (in Chinese)) [10] 余湘娟. 软土的次固结特性试验及计算模型研究[D]. 南京: 河海大学, 2008. (YU Xiang-juan. Secondary consolidation characters and computing mold[D]. Nanjing: Hohai University, 2008. (in Chinese)) [11] JTG E40—2007 公路土工试验规程[S]. 2007: 156-162. (JTGE40—2007 Highway soil test procedures[S]. 2007: 156-162. (in Chinese)) [12] 李国维, 胡 坚, 陆晓岑, 等. 超固结软黏土一维蠕变次固结系数与侧压力系数[J]. 岩土工程学报, 2012, 34(12): 2198-2205. (LI Guo-wei, HU Jian, LU Xiao-cen, et al. One-dimensional secondary consolidation coefficient and lateral pressure coefficient of over consolidated soft clay[J]. Chinese Journal of Geotechnical Engineering, 2012, 34(12): 2198-2205. (in Chinese)) [13] 钱家欢, 殷宗泽. 土工原理和计算[M]. 北京: 中国水利电力出版社, 1994: 44-278. (QIAN Jia-huan, YIN Zong-ze. Geotechnical principles and calculation[M]. Beijing: China Water Power Press, 1994: 44-278. (in Chinese)) [14] 李广信, 张其光, 黄永男, 等. 应力比平面应变试验中主应力转换的研究[J]. 岩土力学, 2006, 27(11): 1867-1872. (LI Guang-xin, ZHANG Qi-guang, HUANG Yong-nan, et al. Study on transforming of principal stress in constant tress ratio plane strain tests[J]. Rock and Soil Mechanics, 2006, 27(11): 1867-1872. (in Chinese))