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

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。

Experimental Study on the Shear Strength of the Straw Fibrous Vegetation Concrete Slope Protection Substrates at the Initial Curing Age

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 of 0% 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.