Laying method of geotextiles on roadbeds, railways and tunnels

Laying method of geotextiles on roadbeds, railways and tunnels

When the geotextile is directly laid on the subgrade surface or road groove surface, the protrusions on the roadbed surface and road groove that may damage the fabric must be removed first, and then the geotextile shall be spread out and laid out on the roadbed or road surface without any wrinkles as much as possible. in the slot. If the ground is very uneven or the debris on the ground is not easy to remove, you can first lay a cushion layer with a thickness of about 15-30cm. If the geotextile is to be spread out in one piece over a longer distance, it should be secured, for example with concrete blocks or stones, to prevent blowing around. When laying materials in areas with low bearing capacity, the transverse direction also needs to be fixed. After the fabric is laid, in order to reduce the damage of sunlight to the fabric, it should be filled with the laying, or protective measures should be taken. Be careful when paving, so as not to puncture the fabric with the tip of the gravel.

In road engineering, there are three construction methods for spreading geotextiles: directly laying on the roadbed; arranging in a road groove with a vertical plane; paving in the road groove and embedding with granules.

① Directly laying on the roadbed: first remove the debris on the ground, then unfold the geotextile, and mark the edge of the geotextile relative to the road centerline with wooden stakes to ensure the correct paving position, as shown in Figure 3-11 (a ) shown.

②In the road groove with vertical plane: Lay the geotextile across the road groove and spread it out in sections without taking special measures. The end folded up is perpendicular to the road groove side, as shown in Figure 3-11 (b).

③ Paved in the road groove and embedded with granular materials: the geotextile is spread across the road groove, and the embedded length at both ends is covered by the side granular berm, and then the geotextile is folded back to the berm, and then embedded with the second layer of base material. , as shown in Figure 3-11 (c).

In railway engineering, due to the different laying conditions of new and existing railway lines, there are different constructions.

①The new railway is laid without traffic interference, and it is easy to ensure the quality. During construction, attention should be paid to checking the drainage slope of the base surface, the quality and quantity of materials, and laying mark piles on the line and paving directly.

② Special attention should be paid to driving safety and construction quality during the laying and construction of existing lines. The construction methods are divided into two types: slow construction and blocked line construction.

The slow-moving construction shall be organized according to the current norms. After the ballast is excavated to the design elevation, the horizontal drainage slope of the base surface is made, and the bottom sand is laid and photographed. Then lay geotextile or geomembrane, then lay sand to make sure, backfill the ballast, and restore the line. According to different conditions, slow construction can be carried out by means of buckle rails, sleeper wood and hanging rails.

Construction of blockade lines The construction of blockade lines shall be handled in accordance with the current norms. When the blockade begins, the ballast bed is excavated, the ballast is removed to the design level, the base surface is trimmed, and a drainage slope (not less than 4%) is set. The bottom sand is patted, and then the geotextile or geomembrane is paved in rolls, and then the surface sand is patted, the ballast is backfilled, and the line operation is carried out to restore the line.

In tunnel engineering, the construction method in the tunnel is basically the same as that of the roadbed, but pay attention to the following points.

① Before laying, the drainage should be handled according to the tunnel conditions, that is, adding or deepening side ditches, drilling scuppers on the side walls of the ditches, and adding lateral blind ditches in some sections.

②The speed limit during construction is 15km/h.

③The damaged bottom concrete block should be chiseled, if necessary, the weak base layer should be excavated, and then sand cushion should be laid to the elevation of the bottom of the tunnel.

2) Connection method of geotextiles

The connection between fabric and fabric generally includes lap joint method, seam joint method, heating joint method and so on.