标准砂冷冻法制样试验研究  

Research on Frozen Sample Preparation of Standard Sand

作　　者：刘忠[1] 宋力[1] 高玉琴[1] 常芳芳[1] 杨小平[1] LIU Zhong;SONG Li;GAO Yuqin;CHANG Fangfang;YANG Xiaoping(Yellow River Institute of Hydraulic Research,Zhengzhou 450003,China)

机构地区：[1]黄河水利科学研究院,河南郑州450003

出　　处：《人民黄河》2019年第3期131-134,共4页Yellow River

基　　金：国家自然科学基金青年科学基金资助项目(51609098);黄河水利科学研究院科研基金资助项目(HKY-JBYW-2014-03)

摘　　要：为了科学评价黄河中下游地区砂土的力学性能,选择砂粒组中的标准砂力学性能指标为参考标准,对其进行一系列三轴固结排水剪切试验,研究了冷冻法制样和湿装法制样对标准砂应力应变关系和抗剪强度指标的影响。结果表明:①无论采用冷冻法制样还是采用湿装法制样,标准砂试样的主应力差都随相对密度的增大呈增大趋势,其应力应变关系曲线从硬化型过渡到软化型。②对于疏松状态的标准砂,轴向应变不大于5%时,湿装法制备试样的主应力差大于冷冻法的;对于密实状态的标准砂,轴向应变不大于6%时,湿装法制备试样的主应力差小于冷冻法的;但随着轴向应变的增大,二者强度趋于一致。③两种制样方法制备的试样,其内摩擦角均随相对密度的增大而增大,不同方法制备试样的内摩擦角相差不大。④对于疏松状态的标准砂采用湿装法制备试样,在装样过程中易受到扰动,导致其峰值强度高于冷冻法的,处于密实状态的标准砂采用湿装法制备试样,装样时对其扰动较少,但其峰值强度低于冷冻法制备试样的,因此对于疏松状态的标准砂建议采用冷冻法制样,且在动三轴试验仪器上进行常规三轴试验,以尽量减少装样对试样的扰动。In order to evaluate the mechanical properties of the sedimentary soil in the middle and lower region of the Yellow River , the standard sand was selected as the reference standard. A series of triaxial consolidation drained shear tests were carried out on saturated standard sand. This paper studied emphatically about the influence of freezing method on the stress-strain relationship and shear resistance indexes of standard sand. The results show that with the increase of relative density , the deviator stress of sample obtained by freezing method or wet method is a trend of growth. And the stress-strain relation curves of sample obtained by both method change from hardening to softening. For loose state standard sand , the deviator stress of sample obtained by wet method is higher than that by freezing method with the axial deformation no more than 5%. However , for the dense state of standard sand , the deviator stress of sample obtained by wet method is less than that by the freezing method with the axial deformation no more than 6%. But their residual strength tends to be the same with the increase of axial strain. Whether frozen sample or moist sample , the internal friction angle of sample increases with the increasing relative density , but the internal friction angle of frozen sample is close to that of moist sample. The sample in the loose state of standard sand prepared by moist method is easy to be disturbed in the installation process , which leads to higher peak strength than that of freezing method. The disturbance is less for the dense state of standard sand with moist method and the peak strength of the sample by freezing method is higher than that of moist method. Therefore , it is suggested to adopt freezing method for the standard sand in loose state and the conventional triaxial test is carried out on the dynamic triaxial shear apparatus in order to minimize installation disturbance.

关 键 词：标准砂 冷冻法 三轴固结排水剪切试验 相对密度 

分 类 号：TV141[水利工程—水力学及河流动力学] TV882.1