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摘要: 为研究地聚合物固化含黏风积沙的持水性能,采用地聚合物对含黏风积沙进行改良,基于压力板仪法测量了不同基质吸力下对应的体积含水率,绘制了相应的土-水特征曲线(SWCC)并进行了模型拟合,探讨了含黏量、地聚合物掺量、龄期和纤维长度对固化风积沙持水性能和拟合参数的影响规律。研究结果表明:随着含黏量由20%提升到30%,风积沙试样在同一吸力下的体积含水率上升了3%左右,持水性显著提升;随着地聚合物掺量由8%提升到12%,20%和30%含黏量固化风积沙SWCC整体上移,10 kPa吸力对应体积含水率分别提升7.0%和5.9%,600 kPa吸力对应体积含水率分别提升4.3%和4.2%;而延长龄期对固化风积沙持水性能的提升较小,体积含水率变化幅度不超过1%;长度为6 mm的玄武岩纤维对固化风积沙持水性能的提升很小,但掺入长度为12 mm的纤维会导致其持水性能稍降低,两者变化幅度均不超过1%;固化含黏风积沙的SWCC具有2个陡降段,可采用分段式Van Genuchten模型拟合;双峰拟合参数能够反映试样大、小孔隙的分布,黏土仅影响大孔隙参数,而地聚合物能够影响大、小孔隙参数;扫描电镜和压汞试验结果表明地聚合物胶结产物和黏土的填充作用降低了土样孔隙率,掺入地聚合物后固化风积沙中孔隙总体积变化较小,一些大孔隙转化为小孔隙,大孔隙峰值密度由0.45 mL·g-1降至0.22 mL·g-1,微孔隙峰值密度由0.02 mL·g-1升至0.05 mL·g-1,孔隙平均尺寸减小;地聚合物水化产物的胶结作用导致土中产生团聚体,包裹了部分自由水并阻碍了水分流失,进而提高了固化风积沙的整体持水性能。Abstract: In order to study the water retention capacity of geopolymer stabilized aeolian sand with clay, the geopolymer was used to stabilize the aeolian sand with clay. Based on the pressure plate instrument method, the volume water contents under different matric suctions were measured, and the soil-water characteristic curves (SWCC) of stabilized aeolian sand were drawn and fitted. The effects of clay content, geopolymer content, curing time, and fiber length on the water retention capacity and fitting parameters of stabilized aeolian sand were studied. Research results show that with the increase in the clay content from 20% to 30%, the volume water content of aeolian sand sample under the same suction increases by about 3%, and the water retention capacity increases significantly. With the increase in the geopolymer content from 8% to 12%, the SWCCs of stabilized aeolian sand with 20% and 30% clay show an overall upward-moving trend, and the corresponding volume water contents with 10 kPa suction increase by 7.0% and 5.9%, and the corresponding volume water contents with 600 kPa suction increase by 4.3% and 4.2%, respectively. However, the extension of curing time has little effect on the improvement of the water retention capacity of stabilized aeolian sand, and the change range of volume water content is less than 1%. Basalt fiber with a length of 6 mm can barely improve the water retention capacity of stabilized aeolian sand. But increasing the fiber length to 12 mm slightly decreases the water retention capacity of stabilized aeolian sand, and the change ranges of both are less than 1%. The SWCC of stabilized aeolian sand with clay has two steep drop sections, which can be fitted by the multi-segment Van Genuchten model. The bimodal fitting parameters can reflect the distributions of large and small pores of the samples. Clay can only affect the parameters of large pores, while the geopolymer can affect the parameters of large and small pores. The scanning electron microscope and the mercury intrusion porosimetry test results show that the filling effects of geopolymer gel and clay reduce the porosity of soil samples. The overall pore volume in the stabilized aeolian sand varies slightly after the geopolymer is added. However, parts of the large pores change into small pores, the peak density of large pores decreases from 0.45 mL·g-1 to 0.22 mL·g-1, the peak density of micro pores increases from 0.02 mL·g-1 to 0.05 mL·g-1, and the average pore size decreases. The cementation of geopolymer leads to the formation of aggregates in the soil, which encapsulates some of the free water and prevents the water loss, improving the overall water retention capacity of stabilized aeolian sand.
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表 1 风积沙与黏土物理力学指标
Table 1. Physical-mechanical parameters of aeolian sand and clay
风积沙 黏土 黏聚力/kPa 内摩擦角/(°) 最大孔隙比 最小孔隙比 液限/% 塑限/% 塑性指数/% 黏聚力/kPa 内摩擦角/(°) 0 44.2 0.892 0.534 32.1 18.8 13.3 7.3 25.6 表 2 风积沙化学成分
Table 2. Chemical compositions of aeolian sand
化学组分 SiO2 Fe2O3 Al2O3 CaO MgO K2O Na2O 烧失量 质量百分比/% 72.35 4.26 11.29 4.36 3.78 2.66 0.85 0.45 表 3 地聚合物化学成分
Table 3. Chemical compositions of geopolymer
化学组分 SiO2 Fe2O3 Al2O3 CaO MgO K2O SO3 Na2O 烧失量 质量百分比/% 粉煤灰 52.34 9.62 24.48 5.00 1.91 2.27 0.46 0.78 3.14 钢渣 31.20 35.40 9.00 8.40 2.40 2.30 3.10 2.74 5.46 水泥 19.40 3.32 6.84 60.60 2.68 0.95 5.26 0.20 0.75 表 4 试验方案
Table 4. Test plan
试样 风积沙与黏粒质量比 地聚合物质量百分比/% 纤维质量百分比/% 纤维长度/mm 20%C 8∶2 0 30%C 7∶3 0 20%C-8%GP(7 d) 8∶2 8 30%C-8%GP(7 d) 7∶3 8 20%C-8%GP-F6(7 d) 8∶2 8 0.5 6 30%C-8%GP-F6(7 d) 7∶3 8 0.5 6 20%C-8%GP(28 d) 8∶2 8 30%C-8%GP(28 d) 7∶3 8 30%C-8%GP-F12(7 d) 7∶3 8 0.5 12 20%C-12%GP(7 d) 8∶2 12 30%C-12%GP(7 d) 7∶3 12 表 5 VG模型拟合参数
Table 5. Fitting parameters of VG model
试样 α n R2 20%C 0.707 1.276 0.954 30%C 0.730 1.206 0.955 20%C-8%GP(7 d) 1.777 1.114 0.875 30%C-8%GP(7 d) 1.519 1.085 0.892 20%C-8%GP(28 d) 2.074 1.106 0.862 30%C-8%GP(28 d) 1.515 1.088 0.915 20%C-12%GP(7 d) 0.414 1.093 0.959 30%C-12%GP(7 d) 0.120 1.090 0.941 20%C-8%GP-F6(7 d) 1.975 1.114 0.863 30%C-8%GP-F6(7 d) 1.300 1.087 0.927 30%C-8%GP-F12(7 d) 2.011 1.089 0.880 表 6 VG模型双峰拟合参数
Table 6. Bimodel fitting parameters of VG model
试样 分界点ψd/
kPaψ≤ψd ψ>ψd α1 n1 R12 α2 n2 R22 20%C 40 0.411 3.225 0.986 0.023 9 1.340 0.974 30%C 40 0.335 3.011 0.989 0.020 2 1.290 0.960 20%C-8%GP(7 d) 40 0.312 2.857 0.994 0.001 8 1.638 0.995 30%C-8%GP(7 d) 40 0.283 2.822 0.998 0.001 7 1.614 0.989 20%C-8%GP(28 d) 40 0.310 2.855 0.999 0.001 9 1.352 0.980 30%C-8%GP(28 d) 40 0.280 2.809 0.997 0.001 9 1.350 0.954 20%C-12%GP(7 d) 80 0.311 1.656 0.967 0.001 5 1.774 0.991 30%C-12%GP(7 d) 160 0.240 1.578 0.945 0.001 3 1.751 0.969 20%C-8%GP-F6(7 d) 80 0.309 2.789 0.995 0.001 9 1.443 0.991 30%C-8%GP-F6(7 d) 80 0.290 2.318 0.993 0.001 7 1.530 0.998 30%C-8%GP-F12(7 d) 40 0.331 2.463 0.984 0.001 8 1.405 0.993 -
[1] ELIPE M G M, LÓPEZ-QUEROL S. Aeolian sands: characterization, options of improvement and possible employment in construction-the state-of-the-art[J]. Construction and Building Materials, 2014, 73(30): 728-39. [2] 郑木莲, 王倩倩, 陈旺, 等. 不同地区风积沙材料特性与剪切强度[J]. 中国科技论文, 2021, 16(4): 415-421. doi: 10.3969/j.issn.2095-2783.2021.04.012ZHENG Mu-lian, WANG Qian-qian, CHEN Wang, et al. Materials characteristics and shear strength of aeolian sand in different areas[J]. China Science Paper, 2021, 16(4): 415-421. (in Chinese) doi: 10.3969/j.issn.2095-2783.2021.04.012 [3] LÓPEZ-QUEROL S, ARIAS-TRUJILLO J, GM-ELIPE M, et al. Improvement of the bearing capacity of confined and unconfined cement-stabilized aeolian sand[J]. Construction and Building Materials, 2017, 153: 374-384. doi: 10.1016/j.conbuildmat.2017.07.124 [4] 冉武平, 赵杰, 黄文薏, 等. 无机处治风积沙强度特性及工程应用研究[J]. 大连理工大学学报, 2018, 58(2): 141-146. https://www.cnki.com.cn/Article/CJFDTOTAL-DLLG201802005.htmRAN Wu-ping, ZHAO Jie, HUANG Wen-yi, et al. Study of strength characteristics and engineering application of inorganic treated aeolian sand[J]. Journal of Dalian University of Technology, 2018, 58(2): 141-146. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-DLLG201802005.htm [5] LI Yu-jie, GUO Zhen, WANG Li-zhong, et al. Shear resistance of MICP cementing material at the interface between calcareous sand and steel[J]. Materials Letters, 2020, 274: 128009. doi: 10.1016/j.matlet.2020.128009 [6] PROVIS J L, BERNAL S A. Geopolymers and related alkali-activated materials[J]. Annual Review of Materials Research, 2014, 44(1): 299-327. doi: 10.1146/annurev-matsci-070813-113515 [7] ZAHMAK A, ABDALLAH M, JARAH B, et al. Environmental performance of alkali-activated binders for ground improvement[J]. Transportation Geotechnics, 2021, 31: 100631. doi: 10.1016/j.trgeo.2021.100631 [8] CHEN Rui, ZHU Yue, LAI Hong-peng, et al. Stabilization of soft soil using low-carbon alkali-activated binder[J]. Environmental Earth Sciences, 2020, 79(22): 1-13. [9] SARGENT P, HUGHES P N, ROUAINIA M, et al. The use of alkali activated waste binders in enhancing the mechanical properties and durability of soft alluvial soils[J]. Engineering Geology, 2013, 152(1): 96-108. doi: 10.1016/j.enggeo.2012.10.013 [10] 滕继东, 贺佐跃, 张升, 等. 非饱和土水气迁移与相变: 两类"锅盖效应"的发生机理及数值再现[J]. 岩土工程学报, 2016, 38(10): 1813-1821. doi: 10.11779/CJGE201610010TENG Ji-dong, HE Zuo-yue, ZHANG Sheng, et al. Moisture transfer and phase change in unsaturated soils: physical mechanism and numerical model for two types of "canopy effect"[J]. Chinese Journal of Geotechnical Engineering, 2016, 38(10): 1813-1821. (in Chinese) doi: 10.11779/CJGE201610010 [11] 姚仰平, 王琳, 王乃东, 等. 锅盖效应的形成机制及其防治[J]. 工业建筑, 2016, 46(9): 1-5. https://www.cnki.com.cn/Article/CJFDTOTAL-GYJZ201609001.htmYAO Yang-ping, WANG Lin, WANG Nai-dong, et al. Mechanism of forming pot-cover effect and its prevention[J]. Industrial Construction, 2016, 46(9): 1-5. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-GYJZ201609001.htm [12] SILLERS W S, FREDLUND D G. Statistical assessment of soil-water characteristic curve models for geotechnical engineering[J]. Canadian Geotechnical Journal, 2001, 38(6): 1297-1313. doi: 10.1139/t01-066 [13] COOK F J. Calculation of hydraulic conductivity from suction permeameter measurements[J]. Soil Science, 1991, 152(5): 321-325. doi: 10.1097/00010694-199111000-00002 [14] 李万双, 孙德安, 高游. 土水特征曲线预测非饱和黏土的抗剪强度[J]. 上海大学学报(自然科学版), 2016, 22(5): 648-655. https://www.cnki.com.cn/Article/CJFDTOTAL-SDXZ201605012.htmLI Wan-shuang, SUN De-an, GAO You. Predicting shear strength of unsaturated clay using soil-water characteristic curve[J]. Journal of Shanghai University (Natural Science), 2016, 22(5) : 648-655. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-SDXZ201605012.htm [15] 陈正汉. 非饱和土与特殊土力学的基本理论研究[J]. 岩土工程学报, 2014, 36(2): 201-272. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201402002.htmCHEN Zheng-han. On basic theories of unsaturated soils and special soils[J]. Chinese Journal of Geotechnical Engineering, 2014, 36(2): 201-272. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201402002.htm [16] 陈正汉, 郭楠. 非饱和土与特殊土力学及工程应用研究的新进展[J]. 岩土力学, 2019, 40(1): 1-54. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201901002.htmCHEN Zheng-han, GUO Nan. New developments of mechanics and application for unsaturated soils and special soils[J]. Rock and Soil Mechanics, 2019, 40(1): 1-54. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201901002.htm [17] 徐永福, 董平. 非饱和土的水分特征曲线的分形模型[J]. 岩土力学, 2002, 23(4): 400-405. doi: 10.3969/j.issn.1000-7598.2002.04.002XU Yong-fu, DONG Ping. Fractal models for the soil-water characteristics of unsaturated soils[J]. Rock and Soil Mechanics, 2002, 23(4): 400-405. (in Chinese) doi: 10.3969/j.issn.1000-7598.2002.04.002 [18] 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. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201307004.htmSUN De-an, ZHANG Jun-ran, LYU Hai-bo. Soil-water characteristic curve of Nanyang expansive soil in full suction range[J]. Rock and Soil Mechanics, 2013, 34(7): 1839-1846. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201307004.htm [19] LU Ning, GODT J W, WU D T. A closed-form equation for effective stress in unsaturated soil[J]. Water Resources Research, 2010, 46(5): 567-573. [20] 张宏, 刘海洋, 李聪. 风积沙路基土土-水特征曲线温度效应研究[J]. 中国公路学报, 2020, 33(7): 42-49. https://www.cnki.com.cn/Article/CJFDTOTAL-ZGGL202007004.htmZHANG Hong, LIU Hai-yang, LI Cong. Temperature effect of soil-water on characteristic curve of aeolian sand subgrade soil[J]. China Journal of Highway and Transport, 2020, 33(7): 42-49. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-ZGGL202007004.htm [21] 张宏, 刘海洋. 含硫酸钠风积沙路基土土-水特征曲线试验研究与模型修正[J]. 中国公路学报, 2020, 33(9): 85-93. https://www.cnki.com.cn/Article/CJFDTOTAL-ZGGL202009010.htmZHANG Hong, LIU Hai-yang. Experimental study and model correction of soil-water characteristic curve of aeolian sand subgrade containing sodium sulfate[J]. China Journal of Highway and Transport, 2020, 33(9): 85-93. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-ZGGL202009010.htm [22] 谭雪琴. 固化剂稳定风积沙路用性能研究[D]. 西安: 长安大学, 2006.TAN Xue-qin. Curing agent aeolian sand road with stable performance[D]. Xi'an: Chang'an University, 2006. (in Chinese) [23] PRINYA C, JAMSAWANG P, SUKONTASUKKUL P, et al. Comparative mechanical performances of cement-treated sand reinforced with fiber for road and pavement applications[J]. Transportation Geotechnics, 2021, 30: 100626-1-15. [24] SIMPSON D C, EVANS T M. Behavioral thresholds in mixtures of sand and kaolinite clay[J]. Journal of Geotechnical and Geoenvironmental Engineering, 2015, 142(2): 04015073. [25] DUXSON P, FERNÁNDEZ-JIMÉNEZ A, PROVIS J L, et al. Geopolymer technology: the current state of the art[J]. Journal of Materials Science, 2007, 42(9): 2917-2933. [26] 蒋勇, 贾陆军, 文梦媛, 等. 碱激发粉煤灰/钢渣胶凝材料的制备[J]. 硅酸盐通报, 2019, 38(7): 2152-2156, 2161. https://www.cnki.com.cn/Article/CJFDTOTAL-GSYT201907027.htmJIANG Yong, JIA Lu-jun, WEN Meng-yuan, et al. Preparation of alkali-activated fly ash/steel slag cementitious materials[J]. Bulletin of the Chinese Ceramic Society, 2019, 38(7): 2152-2156, 2161. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-GSYT201907027.htm [27] YAN Jing-chen, MA Yan-pei, ZHANG Xin, et al. Analysis of frost resistance of basalt fiber cement solidified aeolian sand subgrade[J]. Journal of Physics: Conference Series, 2020, 1654: 012118. [28] PARTO P, KALANTARI B. Laboratory investigation on the effect of polypropylene fibers on the California bearing ratio of stabilized wind-blown sand[J]. Electronic Journal of Geotechnical Engineering, 2011, 16: 1369-1380. [29] 孙银磊, 汤连生, 刘洁. 非饱和土微观结构与粒间吸力的研究进展[J]. 岩土力学, 2020, 41(4): 1095-1122. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX202004001.htmSUN Yin-lei, TANG Lian-sheng, LIU Jie. Advances in research on microstructure and intergranular suction of unsaturated soils[J]. Rock and Soil Mechanics, 2020, 41(4): 1095-1122. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX202004001.htm [30] ZHAI Q, RAHARDJO H. Determination of soil-water characteristic curve variables[J]. Computers and Geotechnics, 2012, 42: 37-43. [31] FREDLUND D G, XING A. Equations for the soil-water characteristic curve[J]. Canadian Geotechnical Journal, 1994, 31(4): 521-532. [32] 田湖南, 孔令伟. 细粒对砂土持水能力影响的试验研究[J]. 岩土力学, 2010, 31(1): 56-60. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201001011.htmTIAN Hu-nan, KONG Ling-wei. Experimental research on effect of fine grains on water retention capacity of silty sand[J]. Rock and Soil Mechanics, 2010, 31(1): 56-60. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201001011.htm [33] 陈仁朋, 王朋飞, 刘鹏, 等. 路基煤矸石填料土-水特征曲线试验研究[J]. 岩土力学, 2020, 41(2): 372-378. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX202002003.htmCHEN Ren-peng, WANG Peng-fei, LIU Peng, et al. Experimental study on soil-water characteristic curves of subgrade coal gangue filler[J]. Rock and Soil Mechanics, 2020, 41(2): 372-378. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX202002003.htm [34] 王叶娇, 王有为, 靳奉雨, 等. 石灰改良土的土水特征曲线及其冻结特征曲线[J]. 防灾减灾工程学报, 2020, 40(6): 967-973. https://www.cnki.com.cn/Article/CJFDTOTAL-DZXK202006016.htmWANG Ye-jiao, WANG You-wei, JIN Feng-yu, et al. Soil-water characteristic curve and freezing characteristic curve of lime lmproved soil[J]. Journal of Disaster Prevention and Mitigation Engineering, 2020, 40(6): 967-973. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-DZXK202006016.htm [35] AL-MAHBASHI A M, AL-SHAMRANI M A, MOGHAL A A B. Soil-water characteristic curve and one-dimensional deformation characteristics of fiber-reinforced lime-blended expansive soil[J]. Journal of Materials in Civil Engineering, 2020, 32(6): 04020125. [36] 荣德政, 唐朝生, 曾浩, 等. 纤维加筋土坯的蒸发过程及抗拉强度特性[J]. 岩土工程学报, 2021, 43(4): 670-678. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC202104012.htmRONG De-zheng, TANG Chao-sheng, ZENG Hao, et al. Evaporation process and tensile behavior of fiber-reinforced rammed earth[J]. Chinese Journal of Geotechnical Engineering, 2021, 43(4): 670-678. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC202104012.htm [37] MALEKZADEH M, BILSEL H. Hydro-mechanical behavior of polypropylene fiber reinforced expansive soils[J]. KSCE Journal of Civil Engineering, 2014, 18(7): 2028-2033. [38] VAN GENUCHTEN M T. A closed-form equation for predicting the hydraulic condictivity of unsatured soils[J]. Soil Science Society of America Journal, 1980, 44(5): 892-898. [39] 高游, 孙德安. 单峰和双峰土水特征曲线基本参数的确定[J]. 岩土工程学报, 2017, 39(10): 1884-1891. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201710023.htmGAO You, SUN De-an. Determination of basic parameters of unimodal and bimodal soil water characteristic curves[J]. Chinese Journal of Geotechnical Engineering, 2017, 39(10): 1884-1891. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201710023.htm [40] HU Mo-zhen, CUI Yu-jun, TAN Yun-zhi. Compaction behaviour of lime-treated metakaolin[J]. Canadian Geotechnical Journal, 2021, 58(8): 1180-1188. [41] SU Y, CUI Yu-jun, DUPLA J C, et al. Soil-water retention behaviour of fine/coarse soil mixture with varying coarse grain contents and fine soil dry densities[J]. Canadian Geotechnical Journal, 2022, 59(2): 291-299.