As the core type of geosynthetics, the pore structure of woven geotextile directly affects the water permeability, filterability and mechanical properties. To optimize the pore structure, it is necessary to ensure the water permeability while avoiding the loss of soil particles. It requires coordinated design from multiple dimensions such as fiber arrangement, weaving process, and material modification.
Fiber diameter and arrangement density are the basic parameters of pore structure. Reducing the fiber diameter (such as from 0.3mm to 0.2mm) can increase the number of fibers per unit area, but it is necessary to avoid excessive density causing pore blockage. Studies have shown that when the fiber arrangement density is controlled at 120-150 fibers/cm², the porosity can reach 40%-45%, which can not only ensure the water permeability coefficient ≥1×10⁻²cm/s, but also effectively intercept soil particles with a particle size of ≥0.075mm.
Traditional flat weaving is prone to uneven pore distribution, and three-dimensional weaving (such as warp knitting-weft knitting composite structure) can form a more complex pore network. By adjusting the interweaving angle of the warp and weft yarns (such as orthogonal weaving and bias weaving), the pore morphology can be transformed from two-dimensional plane pores to three-dimensional stereoscopic pores, thereby improving the pore connectivity. Experiments show that the vertical permeability coefficient of three-dimensional woven geotextile is 20%-30% higher than that of plane weaving.
Heat setting can fix the fiber morphology and reduce pore deformation during use. By controlling the temperature (180-220℃) and time (30-60s), a molten layer is formed on the fiber surface, which not only enhances the bonding between fibers, but also avoids complete fusion and pore closure. For example, the segmented heat setting process can achieve precise control of the porosity within the range of 15%-50%.
Surface coating or chemical modification can adjust the surface properties of the pores. For example, applying a hydrophilic polyurethane coating can increase the pore surface energy by 30%-40%, enhance the wettability to water, and avoid clogging the pores by controlling the coating thickness (5-10μm). Nano-silica modification can form micro-nano structures on the fiber surface, enhance the capillary action of the pores, and promote the directional flow of water.
Composite woven geotextile with non-woven fabrics or films can form a pore gradient structure. For example, woven geotextile with larger pore size (0.1-0.5mm) is laid on the water-facing surface, and non-woven fabric with smaller pore size (0.01-0.1mm) is laid on the back surface to achieve graded interception of "coarse filtration-fine filtration". This structure can make the water permeability coefficient adjustable within the range of 0.01-1cm/s, and at the same time increase the interception efficiency by 15%-20%.
Drawing on the porous structures in nature (such as the surface of lotus leaves and plant vascular bundles), the pore morphology is optimized through bionic design. For example, the use of fractal geometry algorithms to generate a pore network with a self-similar structure can increase the pore connectivity by 25%-35% while reducing local stress concentration. 3D printing technology can achieve precise manufacturing of such complex pore structures.
Adaptive pore structures need to be designed for different application environments (such as frozen soil areas and saline-alkali land). In frozen soil areas, increasing the pore curvature (such as spiral pores) can slow down the rate of water migration and reduce the risk of frost heave; in saline-alkali land, the use of gradient pore structures can preferentially intercept salt crystallization and prevent pore blockage. Experiments show that environmentally adaptive pore design can extend the service life of geotextiles by 30%-50%.
The optimization of the pore structure of woven geotextiles needs to be based on the "water permeability-soil conservation" balance, and through the collaborative innovation of fiber parameters, weaving process, surface modification, composite structure and bionic design, the precise regulation of pore morphology, size and distribution can be achieved. In the future, with the development of intelligent materials and 3D printing technology, dynamic regulation and adaptive optimization of pore structure will become an important research direction, providing technical support for the efficient application of geosynthetics in complex environments.
