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Properties of Geotextiles：
Geotextile is a kind of chemical fiber products. Geotextiles in civil engineering is widely used, geotextile membrane can be divided into two categories: woven geotextile fabric and non-woven geotextile membrane fabric. The woven geotextile is made of polymer to obtain fibers, which are then arranged into threads and woven into fabric with tissue planning on the loom.
The raw material of non-woven fabric is polypropylene and other chemical fiber products, so it has the advantages of strong chemical resistance, high melting point, high strength, etc., while the cost of non-woven fabric is lower, the process is simple, the output is high, and its tensile strength has no significant direction, so non-woven fabric is widely used in the world at present. According to different uses, the specifications of geotextiles are different.
Function and Application of Geotextile Film Membrane:
The function of film geotextiles as building materials is multifaceted. The following basic functions and applications have been recognized by experts, designers and GTM geotextile manufacturers.
(1) Separation:Geotextile can effectively prevent the mixing of two kinds of soil materials with different particle sizes, so as to avoid mixing with each other or loss of soil particles. This function is very important for the construction of highway or railway subgrade in soft soil layer. Experience shows that in some cases, without geotextile, it is impossible to construct engineering on its foundation, because the filling material will sink directly into the underlying soil.
(2) Filtration:The use of geotextile as filter layer has the same effect as that of graded gravel filter layer. Geotextile can make water flow freely without pressure, but it can also prevent the loss of soil fines, so as to avoid the instability and erosion of some projects.
For example:
a: When geotextile is laid under the river block or in the hydraulic structure, the river and lake banks are impacted by the wave or the change of the wave level, and the soil erosion reduces the stability, the geotextile filter layer is laid between the river bank and the revetment, which can prevent the erosion of the soil and the collapse of the river bank.
b: Geotextile is used as drainage ditch geocomposite:Geotextiles prevent the fine particles in the soil from mixing into the graded sand filter layer, so as to prevent the graded sand filter layer from blocking and losing the function of the filter layer, and ensure the quality of the filter layer.
(3) Drainage. The geotextile itself forms a drainage channel, which collects the moisture in the soil into the fabric and slowly removes the soil along the fabric.
a: In some tunnel buildings, a waterproof system must be laid between the shotcrete shells. The system is composed of impermeable synthetic membrane, and the geotextile plays the role of puncture protection and drainage. The seepage water from the rock flows in the geotextile and flows to the drainage pipe at the bottom of the tunnel, so as to prevent the accumulation of water pressure after the diaphragm.
b: In the construction of roads in soft soil areas with high water content, special machines can be used to insert geotextiles into the soil. Groundwater flows out of the ground along the geotextile columns, and enters the permeable sand layer or geotextile layer drainage subgrade.
(4) Reinforcement:
a: Geotextile sandwiched in aggregate geotextile soil foundation system can disperse vehicle load to a large area and reduce the pressure of load on soil foundation. Under the action of load, the deformation of soft soil foundation is caused by the deformation of geotextile embedded in the soil foundation because of its certain toughness and elongation. So that the whole system can form a connection structure, improve the stability of the structure, and improve the bearing capacity of the soil foundation.
b: Geotextile is used as retaining wall. Generally, concrete is used as retaining wall with high cost. Geotextile is used as retaining wall to improve the shear strength of soil layer. At the same time, due to the permeability of geotextile, the water oozing out of the structure will not accumulate water pressure and enhance the stability of the slope.
(5) Filteration:
Due to its good physical and mechanical properties such as isolation, drainage and reinforcement, the filter geotextile also has the good hydraulic characteristics of ensuring the free outflow of pore water and intercepting fine particles at the same time. Although the application on the highway started late, it has achieved good results. Through calculation, analysis and test comparison, Chongqing Institute of highway science, Ministry of Communications The conclusion is as follows:
a: Due to the influence of materials, weaving methods, test methods and other factors, the strength and performance of geotextiles are quite different. The application of geotextiles should be analyzed and properly selected according to the actual situation.
b: The main function of geotextile reinforcement for soft foundation embankment is to limit the lateral displacement of soft foundation and embankment, increase the lateral restraint, thus reduce the stress level and strengthen the stability of embankment, but the reinforcement effect is affected by fabric modulus, soft foundation modulus, soft foundation thickness and other factors.
c: The reinforcement effect of geotextile is related to the construction speed. Generally speaking, the construction speed is fast, the reinforcement effect is good, the construction speed is slow, and the reinforcement effect is not significant.
d: Duncan model is used to couple consolidation theory to carry out finite element analysis of the actual project, which can basically simulate the actual construction situation and provide a better scheme for the design and construction of major embankment.
e: Geotextile is simple and easy to use in practical application, no special equipment is needed, and it can be used in any construction site.
Final Words:
Because of Function and Application,geotextile fabric is widely used in in Civil Engineerings.Also geomembranes can be used in civil engineers.So geosynthetics in civil engineer is commen.