干湿过程中膨胀土最大剪切模量及其预测

陈伟; 孙德安; 张俊然

doi:10.16030/j.cnki.issn.1000-3665.202012033

干湿过程中膨胀土最大剪切模量及其预测

1.
上海大学土木工程系，上海　200444

2.
华北水利水电大学岩土力学与结构工程重点实验室，河南郑州　450045

基金项目: 国家重点研发计划项目(2019YFC1509800)

详细信息

作者简介: 陈伟（1995-），男，硕士研究生，研究方向为非饱和土力学。E-mail：chengwei737475078@qq.com

通讯作者: 孙德安（1962-），男，教授，研究方向为非饱和土力学。E-mail：sundean@shu.edu.cn

中图分类号: TU443

收稿日期: 2020-12-16

修回日期: 2021-01-30

刊出日期: 2021-11-15

The maximum shear modulus of expansive soil during wetting-drying processes and its prediction

1.
Department of Civil Engineering, Shanghai University, Shanghai　200444, China

2.
Henan Province Key Laboratory of Rock and Soil Mechanics and Structural Engineering, North China University of Water Resources and Electric Power, Zhengzhou, Henan　450045, China

More Information

Corresponding author: SUN De’an, sundean@shu.edu.cn

Received Date: 16 December 2020

Revised Date: 30 January 2021

Publish Date: 15 November 2021

摘要

摘要:
为了研究膨胀土在天然环境下的动力特性，本文利用装有弯曲元的三轴仪对南阳膨胀土原状样和重塑样进行了最大剪切模量的测试试验。试验包括在不同围压下的饱和原状南阳膨胀土最大剪切模量测试；将初始干密度相近的原状样和重塑样分别进行脱湿和吸湿，量测整个过程中最大剪切模量的变化，并结合孔隙比进行分析。试验结果表明：饱和南阳膨胀土的最大剪切模量随着围压增大而增大；脱湿过程中南阳膨胀土最大剪切模量与含水率关系曲线要高于吸湿过程的曲线，即最大剪切模量与含水率关系存在滞回特性，这主要是吸力作用的缘故；初始干密度相近条件下原状样的最大剪切模量比重塑样的要小，这是由于原状样内部存在较多大孔隙。本文最后对饱和土最大剪切模量公式进行改进，使之适用于非饱和原状南阳膨胀土最大剪切模量的预测。
- 膨胀土 /
- 最大剪切模量 /
- 弯曲元 /
- 干湿 /
- 预测
Abstract:
In order to examine the dynamic characteristics of expansive soil in natural environment, the maximum shear modulus of undisturbed and remoulded Nanyang expansive soil specimens were tested by using a triaxial apparatus equipping with a pair of bender element. The saturated undisturbed Nanyang expansive soil specimen was tested using the bender element to measure the maximum shear modulus under different confining pressures. The maximum shear modulus of the undisturbed and remoulded specimens with the same dry density were measured in wetting-drying processes and analyzed in combination with the void ratio. The test results indicate that the maximum shear modulus of the saturated Nanyang expansive soil increases with the increasing confining pressure. In the relationship between the maximum shear modulus and water content, the drying curve is higher than the wetting one. It is also found that there is hysteretic characteristics in the maximum shear modulus and water content relationship, which is mainly due to the suction effect. Under similar dry density the maximum shear modulus of undisturbed specimen is smaller than the remoulded one. The reason is that there are more large pores in the undisturbed soil. Finally, an existing formula for the saturated soils is improved for predicting the maximum shear modulus of the unsaturated and undisturbed Nanyang expansive soil.
- expansive soil /
- maximum shear modulus /
- bender element /
- wetting and drying /
- prediction

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图 1 弯曲元系统延迟

Figure 1.

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图 2 南阳原状膨胀土

Figure 2.

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图 3 南阳膨胀土的颗粒曲线

Figure 3.

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图 4 装有弯曲元的三轴仪示意图

Figure 4.

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图 5 弯曲元三轴试样制样模具

Figure 5.

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图 6 饱和原状和重塑膨胀土的最大剪切模量

Figure 6.

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图 7 干湿过程中重塑膨胀土最大剪切模量和孔隙比曲线

Figure 7.

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图 8 干湿过程中原状和重塑样的最大剪切模量

Figure 8.

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图 9 干湿过程中非饱和原状和重塑膨胀土样的孔隙比

Figure 9.

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图 10 含水率20%原状和重塑膨胀土样的孔径分布

Figure 10.

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图 11 饱和土参数拟合

Figure 11.

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图 12 原状南阳膨胀土的实测值与预测值对比

Figure 12.

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表 1 南阳膨胀土基本物理指标

Table 1. Basic physical indexes of the Nanyang expansive soil

石英 /%	伊蒙混层 /%	相对密度 G_s	液限 w_L/%	塑限 w_P/%	塑性指标 I_p	自由膨胀率 δ_f/%
61.0	24.2	2.74	47.5	25.3	22.2	52

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表 2 干湿过程中原状南阳膨胀土参数及最大剪切模量的预测值

Table 2. Parameters and the predicted maximum shear modulus values of the undisturbed Nanyang expansive soil during drying and wetting processes

状态	含水率 w/%	孔隙比e	吸力 s/MPa	饱和度 S_r/%	G_max预测值 /MPa
脱湿过程	19.8	0.668	0.21	81.3	76.2
	15.1	0.577	4.26	71.5	144.0
	11.8	0.532	11.50	60.8	183.0
	7.8	0.503	36.40	42.7	225.0
	3.6	0.484	109.40	20.9	251.0
吸湿过程	7.7	0.521	16.60	40.4	185.0
	11.7	0.567	2.03	56.5	121.0
	15.7	0.625	0.16	69.0	77.1
	19.4	0.674	0.02	78.9	64.1
	20.3	0.689	0.01	80.5	62.0
注：吸力使用WP4C露点水势仪测量，。

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参考文献(21)

[1]	MAIR R J. Developments in geotechnical engineering research: Application to tunnels and deep excavations[J]. Proceedings of the Institution of Civil Engineers and Civil Engineering,1993,97(1):27 − 41. doi: 10.1680/icien.1993.22378
[2]	SHIRLEY D J, HAMPTON L D. Shear-wave measurements in laboratory sediments[J]. The Journal of the Acoustical Society of America,1978,63(2):607 − 613. doi: 10.1121/1.381760
[3]	谢伟, 章定文, 杨声. 含水率对路基压实土小应变剪切模量的影响规律[J]. 岩土力学,2017,38(5):1273 − 1280. [XIE Wei, ZHANG Dingwen, YANG Sheng. Impact of moisture content on variation of small-strain shear modulus of compacted subgrade soil[J]. Rock and Soil Mechanics,2017,38(5):1273 − 1280. (in Chinese with English abstract)
[4]	董林, 王兰民, 夏坤, 等. 原状黄土遇水及饱和后软化特征研究[J]. 水文地质工程地质,2016,43(3):148 − 152. [DONG Lin, WANG Lanmin, XIA Kun, et al. A study of soften characteristics of wet and saturated loess[J]. Hydrogeology & Engineering Geology,2016,43(3):148 − 152. (in Chinese with English abstract)
[5]	ATKINSON J H. Non-linear soil stiffness in routine design[J]. Géotechnique,2000,50(5):487 − 508.
[6]	何芳婵, 李宗坤. 南水北调南阳段弱膨胀土增湿膨胀与力学特性试验研究[J]. 岩土力学,2013,34(增刊2):190 − 194. [HE Fangchan, LI Zongkun. Experimental study of wetting expansibility and mechanical properties of weak expansive soil in Nanyang section of South-to-North Water Diversion Project[J]. Rock and Soil Mechanics,2013,34(Sup2):190 − 194. (in Chinese with English abstract)
[7]	包承纲. 非饱和土的性状及膨胀土边坡稳定问题[J]. 岩土工程学报,2004,26(1):1 − 15. [BAO Chenggang. Behavior of unsaturated soil and stability of expansive soil slope[J]. Chinese Journal of Geotechnical Engineering,2004,26(1):1 − 15. (in Chinese with English abstract) doi: 10.3321/j.issn:1000-4548.2004.01.001
[8]	黄震, 陈铖. 改良膨胀土胀缩裂隙及与抗剪强度的关系研究[J]. 水文地质工程地质,2016,43(3):87 − 93. [HUANG Zhen, CHEN Cheng. A study of the swelling shrinkage cracks of the modified expansive soil and its relationship with the shear strength[J]. Hydrogeology & Engineering Geology,2016,43(3):87 − 93. (in Chinese with English abstract)
[9]	刘祖德, 孔官瑞. 平面应变条件下膨胀土卸荷变形试验研究[J]. 岩土工程学报,1993,15(2):68 − 73. [LIU Zude, KONG Guanrui. Experimental deformation study on unloading expansive soil under plane strain[J]. Chinese Journal of Geotechnical Engineering,1993,15(2):68 − 73. (in Chinese) doi: 10.3321/j.issn:1000-4548.1993.02.008
[10]	孙德安, 黄丁俊. 干湿循环下南阳膨胀土的土水和变形特性[J]. 岩土力学,2015,36(增刊1):115 − 119. [Sun De’an HUANG Dingjun. Soil-water and deformation characteristics of Nanyang expansive soil after wetting-drying cycles[J]. Rock and Soil Mechanics,2015,36(Sup1):115 − 119. (in Chinese with English abstract)
[11]	吕海波, 曾召田, 赵艳林, 等. 膨胀土强度干湿循环试验研究[J]. 岩土力学,2009,30(12):3797 − 3802. [LYU Haibo, ZENG Zhaotian, ZHAO Yanlin, et al. Experimental studies of strength of expansive soil in drying and wetting cycle[J]. Rock and Soil Mechanics,2009,30(12):3797 − 3802. (in Chinese with English abstract) doi: 10.3969/j.issn.1000-7598.2009.12.041
[12]	李朝辉, 程谦恭, 王艳涛, 等. 干湿循环下石灰改良膨胀土离心模型试验研究[J]. 水文地质工程地质,2017,44(4):111 − 117. [LI Zhaohui, CHENG Qiangong, WANG Yantao, et al. A centrifugal model test study of lime-improved expansive soil under drying and wetting circles[J]. Hydrogeology & Engineering Geology,2017,44(4):111 − 117. (in Chinese with English abstract)
[13]	张俊然, 孙德安, 姜彤. 吸力对弱膨胀土应力应变关系和强度的影响[J]. 水利学报,2015,46(增刊1):200 − 204. [ZHANG JUNRAN, Sun De’an, JIANG Tong. Effect of suction on stress-strain relationship and strength of weakly expansive soils[J]. Journal of Hydraulic Engineering,2015,46(Sup1):200 − 204. (in Chinese with English abstract)
[14]	姬美秀, 陈云敏, 黄博. 弯曲元试验高精度测试土样剪切波速方法[J]. 岩土工程学报,2003,25(6):732 − 736. [JI Meixiu, CHEN Yunmin, HUANG Bo. Method for precisely determining shear wave velocity of soil from bender element tests[J]. Chinese Journal of Geotechnical Engineering,2003,25(6):732 − 736. (in Chinese with English abstract) doi: 10.3321/j.issn:1000-4548.2003.06.019
[15]	中华人民共和国住房和城乡建设部. 膨胀土地区建筑技术规范: GBJ 50112—2013[S]. 北京: 中国建筑工业出版社, 2012. Ministry of Housing and Urban-Rural Development of the People’s Republic of China. Technical code for building in expansive soil regions. GBJ 50112—2013[S]. Beijing: China Architecture & Building Press, 2012. (in Chinese)
[16]	MIAO L C, LIU S Y, LAI Y M. Research of soil-water characteristics and shear strength features of Nanyang expansive soil[J]. Engineering Geology,2002,65(4):261 − 267. doi: 10.1016/S0013-7952(01)00136-3
[17]	孙德安, 张俊然, 吕海波. 全吸力范围南阳膨胀土的土-水特征曲线[J]. 岩土力学,2013,34(7):1839 − 1846. [Sun De’an, ZHANG Junran, LYU Haibo. Soil-water characteristic curve of Nanyang expansive soil in full suction range[J]. Rock and Soil Mechanics,2013,34(7):1839 − 1846. (in Chinese with English abstract)
[18]	HARDIN B O, DRNEVICH V P. Shear modulus and damping in soils: design equations and curves[J]. Journal of the Soil Mechanics and Foundations Division, ASCE,1972,98(7):667 − 692. doi: 10.1061/JSFEAQ.0001760
[19]	MARCUSON W F, WAHLS H E. Time effects on dynamic shear modulus of clays[J]. ASCE J Soil Mech Found Div,1972,98(SM12):1359 − 1373.
[20]	LIU X, ZHANG N, LAN H X. Effects of sand and water contents on the small-strain shear modulus of loess[J]. Engineering Geology,2019,260:105202. doi: 10.1016/j.enggeo.2019.105202
[21]	HARDIN B O. The nature of stress-strain behavior for soils[C]//Geotechnical Division Specialty Conference on Earthquake Engineering and Soil Dynamics, ASCE, 1978.