【作者】 唐琳；

【导师】 唐晓武；

【作者基本信息】 浙江大学 ， 岩土工程， 2014， 博士

【摘要】 土工织物作为反滤材料广泛应用于水利、土木、港航等领域。土工织物要实现反滤功能,需满足保土、透水、防淤堵三个反滤准则。孔径是土工织物反滤准则的重要参数。由于土工织物纤维多、孔径小、工作状态应变大,其孔径受拉应变影响很大。而土工织物的孔径指标和测试均在未受拉状态下进行,导致实际应用中原本满足孔径指标的织物反滤失效。因此,本文通过理论分析与试验测试,研究拉应变T (Tensile)、土工织物孔径特征O (Opening)、及反滤性能F (Filtration)三者的关系。1)建立单/双向拉应变与土工织物孔径特征关系的(T-O)理论模型。针对有纺织物平面二维结构,建立单/双向拉应变下有纺织物单孔模型,根据有纺织物基本物理力学参数和拉应变值,分别推导特征孔径(O)及开孔面积率(POA, Percent open area)随单/双向应变变化的理论解；针对无纺织物三维空间结构,基于单向应变下已有两种体系的孔径参数理论解,即佘巍(2011)等效孔径(095)理论解和Rawal(2011)孔径分布曲线(PSD, Pore size distributions)理论解,分别推导不等轴双向应变下无纺织物等效孔径O95bi理论解、及孔径分布曲线PSDbi理论解。2)测试单/双向拉应变与土工织物孔径特征的(T-O)试验关系。通过数字图像法测试单丝条膜有纺织物孔径,在维持拉应变的同时采集图像,定量测试单/双向应变下,有纺织物孔径参数随拉应变的变化规律；通过干筛试验测试单/双向应变下,短纤针刺无纺织物孔径参数随拉应变的变化规律；用拉应变下的土工织物孔径参数理论解预测试验结果,理论值与试验值吻合较好,并得出土工织物孔径参数与拉应变的近似线性关系。3)测试单向拉应变与土工织物反滤性能(T-F)的关系。运用梯度比渗透仪进行淤堵试验,对应反滤设计中透水、保土和防淤堵三个准则,分别测试单向拉应变对透过土工织物的水流速率、漏土量、梯度比的影响。拉应变下的反滤性能试验结果,佐证了孔径随拉应变的变化规律,由此建立了土工织物孔径特征与反滤性能(O-F)的定性关系。4)探讨土工织物泊松比随拉应变的变化规律。通过图像法试验,测试8种有纺及无纺织物泊松比随单向拉应变的变化关系,并与Giroud(2004)提出的可压缩材料和不可压缩材料泊松比变化公式进行对比。更多还原

【Abstract】 As filtration materials, the geotextiles are widely used in water conservancy, civil engineering, port, shipping and other fields. To ensure the effective filtration applications, the pore sizes of geotextiles typically need to meet several criteria, including retention, permeability, and anti-clogging capabilities. Pore size characteristics are important parameters in filtration applications. The filtration applications of geotextiles are usually subjected to tensile loads, whereas the characteristic pore sizes are commonly tested and determined in the unstrained condition, which results in the failure of filtration applications despite the satisfaction of design criteria. The cause of the failure in filtration applications is the influence of tensile strain on pore size characteristics. And the phenomenon of the failure is the influence of tensile strain on filtration properties. Hence, it’s important to study the analytical and experimental relationship among tensile strain (T), pore size characteristics (O), and filtration properties (F) of the geotextiles.1) The analytical relationship between tensile strain and pore size characteristics (the relationship of T-O) have been established. Depending on the two-dimensional structure of woven geotextiles, analytical solutions have been proposed to predict the pore size characteristics of woven slit-film geotextiles under certain uniaxial and biaxial tensile strains. The strained percent open area (POA) and equivalent pore size can be calculated based on the physical properties of the geotextiles and the tensile strains. When it comes to nonwoven geotextiles, the analytical solutions under uniaxial tensile strains have already been proposed to predict the characteristics pore size and the pore size distributions, which are the equations of uniaxial strained equivalent pore size by Wei She (2011), and the equation of uniaxial strained pore size distributions by Rawal(2011). Depending on the three-dimensional structure of nonwoven geotextiles, the analytical solutions about the equivalent pore size Obi95and pore size distributions PSDbi subjected to unequal biaxial tensile strains have been proposed.2) The experimental relationship between tensile strain and pore size characteristics (the relationship of T-O) have been established. The pore size parameters of three woven slit-film geotextiles subjected to several levels of strains were measured by image analysis. The uniaxial and biaxial strained pore size parameters of needle-punched nonwoven geotextiles have been tested by dry sieving. The experimental results were compared with the analytical predictions. The analytical results correlate well with the experimental results, and the pore size parameters change approximately linearly with tensile strains.3) The experimental relationship between tensile strain and filtration characteristics (the relationship of T-F) have been established. Gradient ratio tests are carried out to study the influence of uniaxial tensile strain on the filtration properties of geotextiles. Four kinds of geotextiles (two needle-punched nonwoven and two slit-film woven) are employed in the tests. The flow rate through the geotextiles, quantity of soil passed the geotextile, and the gradient ratio were analyzed depending on the filtration criteria. The variations of filtration characteristics agree with the influences of tesile strains on pore sizes. The relationships between pore size characteristics and filtration characteristics (the relationship of O-F) have been established qualitatively.4) The variations of passion’s ratio of geotextiles subjected to tensile strains have been involved in the analytical solutions of pore size. Hence, image analysis was adopted to determine the passion’s ratio of eight kinds of woven and nonwoven geotextiles. The strained passion’s ratio equations of incompressible and compressible materials have been proposed by Giroud(2004). The experimental results of passion’s ratio were compared with the equations.更多还原