Investigation On Tensile Properties Of Geotextiles For Application

Tensile properties are very important for application of geotextiles. In order to provide theoretical bases and references for practical application, the influence of the specimen width to geotextile's tensile properties and the stress distribution of the holed geotextile were investigated on both experiment and theoretic in this thesis.Based on tensile testing for different width specimens of geotextiles, the relationship between specimen width and breaking strength, breaking elongation, lateral contraction, strength of fixed elongation and elasticity modulus were analyzed. The results show that there is power function between breaking strength and specimen width of geotextile affected by lateral contraction, and the specimen width has no evident effect on geotextile's breaking elongation, but has effect on the strength of fixed elongation when the fixed elongation is larger. The elasticity modulus of geotextile increases a little with increasing of the specimen width.Boundary element method was used to analyze tensile properties of geotextiles. The calculation program of boundary element method for geotextiles was compiled.The relationship between geotextile specimen width and breaking strength was calculated and analyzed with boundary element method program. The results of theoretic and experiment have same regularity. It validates that there is power function between breaking strength and specimen width of geotextile. The stress distribution in the specimen under uniaxial tension was also calculated. The results indicate that there is tensile stress concentration near two sides of the specimen gripped by the clamps, at the same time there is prominent shearing stress concentration on area of the free sides of the specimen near the clamps.The stress distribution on the cross section of geotextile with a circle or an ellipse or a square hole under uniaxial tension or double-axial tension was calculated with boundary element method program. The results show that the stress concentration appear at the range from the hole side to about 3 times of the hole diameter, and the degree of stress concentration near the hole is related to the shape of the hole, the size of the hole, the position of the hole and the dimension of the specimen. The stressconcentration near the hole of different shape is also related to the tensile condition. When the specimen bears uniaxial tension or double-axial tension, the value of the maximum stress near the hole side is different and the position of the maximum stress is also different.The tensile testing of geotextile specimen with a circle hole or a square hole was carried out in order to testify the results of boundary element method. Comparing the theoretical breaking strength with the experimental breaking strength of the holed geotextile specimen, they change as uniform trend though the theoretical results are lower than the experimental results. It was proved that there is stress concentration near the hole on holed geotextile by recording the tensile process of the holed geotextile specimen. The method of reasonable application of holed geotextiles has also been put forward.