Mechanical Properties and Water Holding Characteristics of Initially Isotropic Soils and Transversely Isotropic Soils
-
摘要: 为了探讨不同初始状态下非饱和黄土的力学性质和水量变化规律之间的差异，提出了制备各向同性及横观各向同性试样的方法，用改进的非饱和土三轴仪对制备的各向同性、横观各向同性及常规重塑试样进行了72个三轴固结排水剪切试验. 试验结果表明：对不同削样角度的各向同性试样进行试验验证，发现其近似各向同性；3种不同初始状态下各向同性非饱和试样的破坏应力最大，横观各向同性非饱和试样次之；横观各向同性试样在剪切阶段的初始切线模量最大，其他两组试样的初始切线模量较小且近似相等；各向同性试样及横观各向同性试样在剪切的初始阶段均有轻微的剪胀现象，常规重塑试样均处于剪缩状态；不同初始状态下的各非饱和试样在剪切阶段吸力变化对排水的影响并不显著，其中横观各向同性试样的偏应力-含水率关系曲线的斜率绝对值最小，其他两组试验的斜率几乎相同，各向同性、横观各向同性及常规的重塑试样的力学特性及持水特性不尽相同. 本文的研究成果可为不同初始状态下各模型的建立及工程应用提供有益的参考.Abstract: In order to investigate the difference between the mechanical properties and water quantity variation of unsaturated loess under different initial conditions, a method for preparing isotropic and transversely isotropic specimens was suggested. An improved triaxial apparatus for unsaturated soils was used to carry out 72 consolidated drained triaxial tests on prepared isotropic, transversely isotropic and regular specimens. Isotropic samples with different cutting angles were studied experimentally and found to be approximately isotropic. For three different initial states, the failure stress of the isotropic unsaturated specimen is the largest, followed by that of the transversely isotropic unsaturated specimen; the initial tangent modulus of the transversely isotropic specimen is the largest at the shear stage, while those of the other two groups are smaller and approximately equal. Both the isotropic and transversely isotropic specimens have slight dilatancy at the initial stage of shear, while all ordinary remoulded specimens are in the state of shear contraction. Under different initial conditions, the change of the suction of unsaturated samples has little effect on the drainage, the absolute slope value of the deviator stress-water content curve of the transversely isotropic sample is the lowest, and those of the other two groups are almost the same. The mechanical properties and water holding characteristics of the isotropic, transversely isotropic and ordinary remoulded specimens are different. The research results obtained may provide a useful reference for the establishment of different models of soil under different initial conditions and for various engineering applications.
-
图 1 不同角度各向同性试样切削过程
Figure 1. Cutting process of isotropic specimens with different angles
图 2 各向同性试样q-
$ {\varepsilon _{\rm a}}$ 关系曲线Figure 2. Relation curves of q-
${\varepsilon _{\rm a}}$ for isotropic specimens
图 3 各向同性试样
${\varepsilon _{\rm{a}}}$ -${\varepsilon _{\rm{v}}} $ 关系曲线Figure 3. Relation curves of
${\varepsilon _{\rm{a}}}$ -${\varepsilon _{\rm{v}}}$ for isotropic specimens
图 4 横观各向同性 −K0预固结试样及常规重塑试样的
$q$ -$ {\varepsilon _{\rm{a}}}$ 及${\varepsilon _{\rm{a}}} $ -$ {\varepsilon _{\rm{v}}}$ 关系曲线Figure 4. Relation curves of
$q$ -$ {\varepsilon _{\rm{a}}}$ and${\varepsilon _{\rm{a}}}$ -${\varepsilon _{\rm{v}}}$ for transversely isotropic specimens and remolded samples
图 5 起始切线模量随净围压的变化
Figure 5. Variation of
$\lg ({E}/{P_{\rm{a}}})$ with$\lg (p/{P_{\rm{a}}})$ 
图 6 3组试样的q-
$ w$ 关系曲线Figure 6. Relation curves of q-
$ w$ for different group specimens表 1 土样的基本物理指标
Table 1. Physical parameters of soil samples
相对密度ds 塑限wp/% 液限wL/% 最大干密度
${\rho _{{\rm d}\max }}$/（g•cm−1）最优含水率wop/% 2.71 17.3 31.1 1.91 12.5 
下载: 导出CSV
表 2 试验研究方案
Table 2. Experimental research programs
试验组别 试验简称 控制竖向压力/kPa 削样角度/（°） 控制净围压/kPa 控制基质吸力/kPa 1 各向同性试验 0 100、200、300 50、100、200 45 60 90 2 K0CD试验 100 100、200、300 0、50、100、200 200 3 CD试验 100、200、300 0、50、100、200
下载: 导出CSV
表 3 土样的强度参数
Table 3. Strength parameters
吸力/kPa 净围压p/kPa qf/kPa pf/kPa φ/（°） c/kPa 各向
同性K0CD
试验CD
试验各向
同性K0CD
试验CD
试验各向
同性K0CD
试验CD
试验各向
同性K0CD
试验CD
试验0 100 367.7 201.3 226.6 167.1 31.39 26.51 41.63 16.11 200 596.2 400.9 398.7 333.7 300 831.0 521.5 593.7 473.8 50 100 341.5 312.1 276.0 213.8 204.0 192.0 26.61 28.93 27.13 58.08 37.25 30.98 200 524.1 503.8 424.5 374.7 367.9 341.5 300 665.4 686.9 610.8 521.8 529.0 503.6 100 100 399.0 333.0 325.5 229.7 211.0 208.3 28.44 30.04 28.21 67.07 42.07 47.90 200 564.3 557.7 525.1 388.1 385.9 375.0 300 768.4 733.0 683.8 556.1 544.3 527.9 200 100 447.4 433.3 409.3 249.1 244.4 236.4 31.35 31.61 29.2 70.56 62.61 67.50 200 704.9 666.0 605.4 435.0 422.0 410.7 300 892 873.8 790.3 602.7 591.3 563.4
下载: 导出CSV
表 4 剪切过程中土样的q-w关系曲线的斜率
Table 4. Slope of the q-w relation curve of soil samples in the shear process
试样 吸力/kPa 净围压/kPa $\alpha$/（× 10–5） 各吸力下$\alpha$的平均值/（× 10–5） 平均值/（× 10–5） 各向同性 50 100 –3.27 –2.68 –2.62 200 –2.63 300 –2.15 100 100 –3.09 –2.61 200 –2.48 300 –2.26 200 100 –3.30 –2.56 200 –2.39 300 –2.00 横观各向同性 0 100 –4.98 –4.43 –1.55 200 –4.06 300 –3.72 50 100 –2.16 –1.55 200 –1.33 300 –1.16 100 100 –1.44 –1.52 200 –1.84 300 –1.27 200 100 –1.63 –1.59 200 –1.69 300 –1.45 重塑 0 100 –6.82 –5.46 –2.59 200 –5.05 300 –4.50 50 100 –3.02 –2.47 200 –2.49 300 –1.89 100 100 –2.95 –2.48 200 –2.49 300 –1.99 200 100 –3.20 –2.83 200 –2.78 300 –2.52
下载: 导出CSV
-
曾国熙,龚晓南,盛进源. 正常固结黏土K0固结剪切试验研究[J]. 浙江大学学报,1987,21(2): 1-9.ZENG Guoxi, GONG Xiaonan, SHENG Jinyuan. Research on normally consolidated clay by K0 consolidated shear test[J]. Journal of Zhejiang University, 1987, 21(2): 1-9. 黄茂松,宋晓宇,秦会来. K0固结粘土基坑抗隆起稳定性上限分析[J]. 岩土工程学报,2008,30(2): 250-255. doi: 10.3321/j.issn:1000-4548.2008.02.016HUANG Maosong, SONG Xiaoyu, QIN Huilai. Basal stability of braced excavations in K0-consolidated soft clay by upper bound method[J]. Chinese Journal of Geotechnical Engineering, 2008, 30(2): 250-255. doi: 10.3321/j.issn:1000-4548.2008.02.016 李校兵,郭林,蔡袁强,等. K0固结饱和软黏土的三轴应力路径试验研究[J]. 中南大学学报(自然科学版),2015,46(5): 1820-1825.LI Xiaobing, GUO Lin, CAI Yuanqiang, et al. Stress path triaxial tests on K0-consolidated saturated soft clay[J]. Journal of Central South University (Science and Technology), 2015, 46(5): 1820-1825. 王立忠,叶盛华,沈恺伦,等. K0固结软土不排水抗剪强度[J]. 岩土工程学报,2006,28(8): 970-977. doi: 10.3321/j.issn:1000-4548.2006.08.008WANG Lizhong, YE Shenghua, SHEN Kailun, et al. Undrained shear strength of K0 consolidated soft clays[J]. Chinese Journal of Geotechnical Engineering, 2006, 28(8): 970-977. doi: 10.3321/j.issn:1000-4548.2006.08.008 褚福永,朱俊高,王平,等. K0固结条件下粗粒土变形及强度特性研究[J]. 岩土力学,2012,33(6): 1625-1630. doi: 10.3969/j.issn.1000-7598.2012.06.005CHU Fuyong, ZHU Jungao, WANG Ping, et al. Study of deformation and strength characteristics of coarse grained soil under K0-consolidation condition[J]. Rock and Soil Mechanics, 2012, 33(6): 1625-1630. doi: 10.3969/j.issn.1000-7598.2012.06.005 吕玺琳,钱建固,黄茂松. 不排水加载条件下K0固结饱和砂土失稳预测[J]. 岩土工程学报,2015,37(6): 1010-1015.LÜ Xilin, QIAN Jiangu, HUANG Maosong. Prediction of instability of K0-consolidated saturated sands under undrained loading conditions[J]. Chinese Journal of Geotechnical Engineering, 2015, 37(6): 1010-1015. 刘清秉,吴云刚,项伟,等. K0及三轴应力状态下压实膨胀土膨胀模型研究[J]. 岩土力学,2016,37(10): 2795-2802.LIU Qingbing, WU Yungang, XIANG Wei, et al. Swelling model study of expansive soil at K0 and triaxial stress state[J]. Rock and Soil Mechanics, 2016, 37(10): 2795-2802. 程海涛, 刘保健, 谢永利. 压实黄土连续加载K0固结特性[J]. 岩石力学与工程学报, 2007, 26（增刊1）: 3203-3208CHENG Haitao, LIU Baojian, XIE Yongli. K0 consolidation characteristics of compacted loess under continuous loading[J]. Chinese Journal of Rock Mechanics and Engineering, 2007, 26(S1): 3203-3208 侯伟,姚仰平,崔文杰. K0超固结土的不排水抗剪强度[J]. 力学学报,2008,40(6): 795-803. doi: 10.3321/j.issn:0459-1879.2008.06.010HOU Wei, YAO Yangping, CUI Wenjie. Undrained shear strength of K0 over consolidated soil[J]. China Journal of Theoretical and Applied Meachanics, 2008, 40(6): 795-803. doi: 10.3321/j.issn:0459-1879.2008.06.010 刘俊卿,李倩,王保实. 考虑横观各向同性疲劳损伤的 沥青路面数值模型[J]. 西南交通大学学报,2016,51(4): 1-9.LIU Junqing, LI Qian, WANG Baoshi. Numerical model of asphalt pavement considering transversely isotropic fatigue damage[J]. Journal of Southwest Jiaotong University, 2016, 51(4): 1-9. 殷宗泽. 土体本构模型剖析[J]. 岩土工程学报,1996,18(4): 95-97. doi: 10.3321/j.issn:1000-4548.1996.04.016YIN Zongze. Analysis of soil constitutive model[J]. Chinese Journal of Geotechnical Engineering, 1996, 18(4): 95-97. doi: 10.3321/j.issn:1000-4548.1996.04.016 陈正汉. 重塑非饱和黄土的变形、强度、屈服和水量变化特性[J]. 岩土工程学报,1999,21(1): 82-90. doi: 10.3321/j.issn:1000-4548.1999.01.018CHEN Zhenghan. Deformation,strength,yield and moismre change of a remolded unsaturated loess[J]. Chinese Journal of Geotechnical Engineering, 1999, 21(1): 82-90. doi: 10.3321/j.issn:1000-4548.1999.01.018 殷宗泽,周建,赵仲辉,等. 非饱和土本构关系及变形计算[J]. 岩土工程学报,2006,28(2): 137-146. doi: 10.3321/j.issn:1000-4548.2006.02.003YIN Zongze, ZHOU Jian, ZHAO Zhonghui, et al. Constitutive relations and deformation calculation for unsaturated soils[J]. Chinese Journal of Geotechnical Engineering, 2006, 28(2): 137-146. doi: 10.3321/j.issn:1000-4548.2006.02.003 ALONSO E E, GENS A, JOSA A. A constitutive model for partially saturated soils[J]. Géotechnique, 1990, 40(3): 405-430. doi: 10.1680/geot.1990.40.3.405 SHENG D, FREDLUND D G, GENS A. A new modelling approach for unsaturated soils using independent stress variables[J]. Canadian Geotechnical Journal, 2008, 45(4): 511-534. doi: 10.1139/T07-112 卢再华,陈正汉,蒲毅斌. 原状膨胀土损伤演化的三轴CT试验研究[J]. 水利学报,2002(6): 106-112. doi: 10.3321/j.issn:0559-9350.2002.06.019LU Zaihua, CHEN Zhenghan, PU Yibin. Study on damage evolution of natural expansive soil with computerized tomography during triaxial shear test[J]. Shuili Xuebao, 2002(6): 106-112. doi: 10.3321/j.issn:0559-9350.2002.06.019 朱元青,陈正汉. 原状Q3黄土在加载和湿陷过程中细观结构动态演化的CT-三轴试验研究[J]. 岩土工程学报,2009,31(8): 1219-1228. doi: 10.3321/j.issn:1000-4548.2009.08.011ZHU Yuanqing, CHEN Zhenghan. Experimental study on dynamic evolution of meso-structure of intact Q3 loess during loading and collapse using CT and triaxial apparatus[J]. Chinese Journal of Geotechnical Engineering, 2009, 31(8): 1219-1228. doi: 10.3321/j.issn:1000-4548.2009.08.011 -
下载:
点击查看大图
计量
- 文章访问数: 508
- HTML全文浏览量: 264
- PDF下载量: 28
- 被引次数: 0