高应力下粗砂与混凝土接触面剪切特性影响因素试验研究

Experimental investigation of the influential factors on the shear characteristics of the interface between coarse sand and concrete under high stress

利用改装自RMT-150B的直剪试验仪在不同法向应力下进行了含水量为0%、8%、16%、24%的粗砂与具有4种不同粗糙度、强度混凝土基底的接触面直剪试验。试验结果表明:当法向应力等于2MPa时,随接触面粗糙度的增加,达到极限抗剪强度的剪切位移先增加后减小;当法向应力大于2MPa时,达到极限剪切强度的剪切位移基本不再随接触面粗糙度而变化;在法向应力相同的情况下,干砂初始抗剪刚度较湿砂大。依据试验数据回归分析可知:高应力直剪条件下,粗砂与混凝土接触面的剪应力剪切位移关系可用双曲线模型描述。直观分析结果表明:极限抗剪强度受法向应力影响最大,且与应力呈线性相关,其次为接触面粗糙度,含水量的影响略高于混凝土界面强度;初始抗剪刚度随法向应力、接触面粗糙度、基底硬度的增大而增大,接触面初始剪切刚度所受因素影响从大到小依次为法向应力、含水量、接触面粗糙度、基底硬度;颗粒相对破碎受法向应力影响最大,其次为含水量,再次为基底硬度,接触面粗糙度影响最小,并且颗粒相对破碎随法向应力增达而增大,随混凝土粗糙度与基底硬度的增大而减小,随含水量增加存在破碎的破碎峰值。

The direct shear apparatus amended from the RMT-150B system is adopted to conduct the direct shear test on the coarse sand with the water contents of 0%,8%,16%and 24%,respectively.The contact surfaces with four kinds of concrete basements with different roughness and strengths under different normal stresses are considered.The results have proved that the ultimate shearing strength under high stress increases with the normal stress.The shearing rigidity decreases with the shear displacement development while the initial shearing rigidity decreases when the normal stress increases.The shear displacement keeps increasing as the roughness of the contact surface grows up to a normal stress of 2 MPa.The initial shearing rigidity of the dry sand with the water content of 0%is greater than that of the wet sand under the same normal stress.Regression analysis based on the experimental data shows that the displacement for the contact surface between the coarse sand and concrete under the high-stress direct shear conditions can be described via the hyperbolic model.In addition,the ultimate and initial shearing strength of the contact surface can be estimated through the regression parameters.It has been shown that the ultimate shearing strength is the most significantly influenced by the normal stress followed by the roughness of the contact surface,and the influence of the water content is slightly greater than the strength of the concrete interface.The relative crushing ration of particles is subjected to the significant influence from the normal stress,followed by the water content and basement hardness and the influence from the contact surface roughness is minimum.In addition,the relative crushing ratio of particles increases as the normal stress develops and decreases while the concrete roughness and basement hardness become smaller.The peak of the existing crush increased with the water content.