秸秆纤维型植被混凝土边坡防护基材初期抗剪强度试验研究
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摘要
针对边坡防护过程中产生的基材局部性张拉、开裂、垮落等问题,以秸秆纤维作为基材改良剂,考虑水泥与秸秆纤维2个因素,考察基材7 h、1 d、3 d、7 d、14 d、28 d抗剪强度特征。试验结果表明:水泥掺量的增加与养生龄期的延长可以提高未掺入秸秆基材的剪应力,秸秆纤维的掺入可以提高基材延性,延缓基材剪切破坏过程,且增加秸秆掺量可有效提高各配比基材的剪应力和黏聚力,但对内摩擦角效果并不明显,其11%水泥基材中4%秸秆掺量7 h剪应力较0%秸秆增大54.68%,黏聚力增大136%,较3 d剪应力增大42.15%,黏聚力增大206%;秸秆纤维对植被混凝土基材剪切强度的增大并非线性,而是随养生龄期的延长与水泥掺量的增加出现一定的弱化,其11%水泥基材中4%秸秆掺量28 d剪应力较0%秸秆降低了18.83%,黏聚力降低32.87%,较14 d剪应力增大11.84%,黏聚力降低15.73%,其弱化程度与水泥掺量和养生环境密切相关。
In view of the problems of local tension,cracking and collapse of the base material in the process of slope protection,the shear strength characteristics of the base material for 7 h,1 d,3 d,7 d,14 d and 28 d were investigated by using straw fiber as the base material modifier and considering two factors of cement and straw fiber. The experimental results showed that the increase of cement content and the prolongation of curing age increased the shear stress of the base material without straw fiber,the addition of straw fiber improved the ductility of the base material and delayed the shear failure process of the base material,and the increase of straw content effectively improved the shear stress and cohesion of the base material with different proportions,but had less impact on internal friction angle. The shear stress and cohesion of base material with 11% of cement and 4% of straw content for 7 h was increased by 54.68% and 136% separately,comparing with that of0% straw;that for 3 d were increased by 42.15% and 206% respectively. The straw fiber had not a linear increasing effect on the shear strength of vegetation concrete base material,but weakened with the prolongation of curing age and the increase of cement content. The shear stress of base material with 4% straw and 11% cement for 28 day was decreased by 18.83%,and its cohesion was decreased by 32.87%,comparing with that of 0% straw,and yet its shear stress is higher by 11.84% and the cohesion is lower by 15.73% than that for 14 d. Thus,its weakening degree is closely related to the cement content and the curing environment.
In view of the problems of local tension,cracking and collapse of the base material in the process of slope protection,the shear strength characteristics of the base material for 7 h,1 d,3 d,7 d,14 d and 28 d were investigated by using straw fiber as the base material modifier and considering two factors of cement and straw fiber. The experimental results showed that the increase of cement content and the prolongation of curing age increased the shear stress of the base material without straw fiber,the addition of straw fiber improved the ductility of the base material and delayed the shear failure process of the base material,and the increase of straw content effectively improved the shear stress and cohesion of the base material with different proportions,but had less impact on internal friction angle. The shear stress and cohesion of base material with 11% of cement and 4% of straw content for 7 h was increased by 54.68% and 136% separately,comparing with that of0% straw;that for 3 d were increased by 42.15% and 206% respectively. The straw fiber had not a linear increasing effect on the shear strength of vegetation concrete base material,but weakened with the prolongation of curing age and the increase of cement content. The shear stress of base material with 4% straw and 11% cement for 28 day was decreased by 18.83%,and its cohesion was decreased by 32.87%,comparing with that of 0% straw,and yet its shear stress is higher by 11.84% and the cohesion is lower by 15.73% than that for 14 d. Thus,its weakening degree is closely related to the cement content and the curing environment.
引文
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[2]Li Laibo,Chen Mingxu,Zhou Xiangming,et al.A case of water absorption and waterfertilizer retention performance of super absorbent polymer modified sulphoaluminate cementitious materials[J].Construction and Building Materials,2017,150(1):538-546.
[3]周正军,许文年,刘大翔,等.岩质边坡植被混凝土护坡基材力学稳定性探讨[J].三峡大学学报:自然科学版,2010,32(3):57-60.Zhou Zhengjun,Xu Wennian,Liu Daxiang,et al.Discussion on substrate stability of rock slope protection with vegetation-growing concrete[J].Journal of China Three Gorges University:Natural Sciences,2010,32(3):57-60.
[4]Fan J G,Huang C L,Yang C H,et al.Effect evaluation of shotcrete vegetation mulching technique applied to steep concrete-face slopes on a highway of Taiwan[J].Paddy and Water Environment,2013,11(1):145-159.
[5]许文年,夏振尧,周宜红,等.植被混凝土无侧限抗压强度试验研究[J].水利水电技术,2007,38(4):51-54.Xu Wennian,Xia Zhenyao,Zhou Yihong,et al.Experimental investigation of unconfined compression strength of vegetation-growing concrete[J].Water Resources and Hydropower Engineering,2007,38(4):51-54.
[6]夏振尧,许文年,王乐华.植被混凝土生态护坡基材初期强度特性研究[J].岩土力学,2011,32(6):1719-1724Xia Zhenyao,Xu Wennian,Wang Lehua.Research on characteristics of early strength of ecological slope-protected base material of vegetation-growing concrete.[J]Rock and Soil Mechanics,2011,32(6):1719-1724
[7]夏振尧,周正军,黄晓乐,等.植被护坡根系浅层固土与分形特征关系初步研究_夏振尧[J].岩石力学与工程学报,2011,30(S2):3641-3647.Xia Zhenyao,Zhou Zhengjun,Huang Xiaole,et al.Preliminary study of relationship between shallow soil reinforcement and fractal characteristics of vegetation roots in biotechnical slope protection[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(S2):3641-3647.
[8]Martha O A,Mark T,Standish R J.Correlation between soil development and native plant growth in forest restoration after surface mining[J].Ecological Engineering,2017,106:209-218.
[9]贾尚华.石灰水泥复合土固化机理及力学性能的试验研究[D].呼和浩特:内蒙古农业大学,2011.Jia Shanghua.Reinforcement Mechanism and Mechanical Properties of Lime-Cement Soil[D].Huhehaote:Inner Mongolia Agricultural University,2011.
[10]武华荟,刘宝举.硅酸盐水泥水化机理研究方法[J].粉煤灰,2009,21(1):33-36.Wu Huahui,Liu Baoju.Research method of silicate cement hydration mechanism[J].Coal Ash,2009,21(1):33-36.
[11]郦建俊.水泥土的强度特性、固结机理与本构关系的研究[D].西安:西安建筑科技大学,2005.Li Jianjun.Research on the Characteristics in Strength、Concretion Mechanism and Constitutive Relationship of the Cement-loess[D].Xi'an:Xi'an University of Architecture and Technology,2005.
[12]孔祥明,卢子臣,张朝阳.水泥水化机理及聚合物外加剂对水泥水化影响的研究进展[J].硅酸盐学报,2017,45(2):274-281.Kong Xiangming,Lu Zichen,Zhang Chaoyang.Recent development on understanding cement hydration mechanism and effects of chemical admixtures on cement hydration[J].Journal of the Chinese Ceramic Society,2017,45(2):274-281.
[13]李云峰,李志国,郑刚.纤维水泥土力学性能试验研究[J].建筑科学,2004,20(6):56-60.Li Yunfeng,Li Zhiguo,Zheng Gang.A study for properties of cement-soil reinforced with randomly distributed discrete fibers[J].Building Science,2004,20(6):56-60.
[14]鹿群,郭少龙,王闵闵,等.纤维水泥土力学性能的试验研究[J].岩土力学,2016,37(S2):421-426.Lu Qun,Guo Shaolong,Wang Minmin,et al.Experimental study of mechanical properties of fiber cement[J].Rock and Soil Mechanics,2016,37(S2):421-426.
[15]李华明.聚丙烯纤维混凝土性能研究及其在隧道工程中的应用[D].成都:西南交通大学,2005.Li Huaming.Study on the Properties of Polypropylene Fiber Concrete and Its Application in Tunnel Engineering[D].Chengdu:Southwest Jiaotong University,2005.
[16]姚燕,贺祖浩.不同种类纤维对水泥土力学性质影响试验研究[J].三峡大学学报:自然科学版,2016,38(1):41-44.Yao Yan,He Zuhao.Experimental study of effects of different kinds of fibers on mechanical properties of cement soils[J].Journal of China Three Gorges University:Natural Sciences,2016,38(1):41-44.