Pore Size Characteristics Of Geotextiles Subjected To Lateral Limited Uniaxial Tensile Strains

Geotextiles are widely used as an anti-filtration material in engineering practice such as anti-filtration,waterproofing and isolation.Geotextiles need to meet the three criteria of soil retention,permeability,and anti-clogging capabilities when designing reverse filtration.The pore size of the fabric is an important parameter for reverse filtration design.The geotextiles in engineering applications are basically under tension in different situations,but the pore size parameters in the current filter design specifications do not consider the tension situation.After the geotextiles are stretched,their pore size will change,which will have a greater impact on the filtration performance of the fabric,and even cause the filtration failure.The complexity of soil deformation is easy to cause geotextiles to be in different stress states.When the fabric is on the surface of the protection body or the overlying load is small,such as the fabric on the surface of the dam,the soil deformation is easy to make it in a lateral limited uniaxial tensile strain state.Based on the previous analytical research,this paper studies the variation law of geotextiles pore size characteristics under the lateral limited uniaxial tensile strain that has not yet been developed,and derives the analytical solution for the characteristic parameters of geotextiles pore diameter,and verifies it by lateral limited uniaxial tensile test.1)Woven geotextiles can be regarded as a two-dimensional planar structure.Based on the microstructure and mechanical characteristics of the textile,a single-hole model of the textile is established to derive the analytical solutions about the percent open area(POAl)and equivalent pore size(O95l)of the textile under the lateral limited uniaxial tensile strain.2)Digital image analysis was used to measure the pore size characteristic parameters of the three types of woven geotextiles under lateral limited uniaxial tensile strain.The pore size characteristics parameters of the geotextiles under various strains were statistically calculated,including the percent open area,characteristic pore sizes(O95?O50?O30),and pore size distributions(PSD).The experimental value is compared with the analytical solution,and the change law of the pore size is summarized.3)Non-woven geotextiles belong to a three-dimensional layered structure.The previous theory of the effects of tensile strain on the pore diameter of non-woven fabrics is mainly divided into two analytical systems.Based on the two analytical systems,this paper establishes analytical solutions for the equivalent pore size(O95l)and pore size distributions(PSDl)of non-woven geotextiles under the lateral limited uniaxial tensile strain.4)The non-woven geotextiles were lateral limited uniaxial-stretched using a biaxial stretcher,in which a special self-made ring fixture was used to maintain the tensile.The dry sieve test was adopted to eliminate the influence of electrostatic effects,and the pore size distribution curves of two kinds of staple fiber needle punched nonwovens with different unit area mass were tested,and the characteristic pore size values were obtained on the curves.The experimental values and analytical calculations are compared and analyzed to verify the rationality of the analytical prediction of the geotextiles pore change of the two systems under the lateral limited uniaxial tensile strain.Finally,the predictions of the two analytical systems are compared,and the change law of the pore size of the nonwoven geotextiles under the lateral limited uniaxial tensile strain is summarized,which establishes the basis for related research in engineering practice.