Methods for making lightning protection grounding nets under geological conditions such as saline-alkali weathered stones in alpine areas
This article uses the method of building a well for grounding; (mainly for the rock level) Mountains are generally rocky, and it is not impossible to build a grounding network on the rocks. A hole of φ200*2000-3000mm (depending on the environment) is drilled under the surface soil layer, and the bottom is blasted to crush the formation rock to form a gap. The filler is poured into the non-metallic grounding body (sintered type) vertically, and then high After adding the molecular resistance reducing agent, add water appropriately. After adding water and sinking for 3-4 hours, add the anhydrous polymer resistance reducing agent and an appropriate amount of filler, and then compact it 800mm away from the surface soil layer. At this point, the vertical ground body is laid, and the horizontal grounding grid is laid. Horizontal grounding The ground network uses more than 35 square meters of copper cables. After peeling, apply conductive glue appropriately and make a horizontal ground network cable trough 500 mm away from the ground surface. The width of the cable trough is 200 mm. Apply anhydrous polymer resistance reducing agent and an appropriate amount of filler to the cable trough. Press the cables that have been painted with conductive glue. After laying it according to the grid shape, bury the soil and compact it; the grounding distance of the grounding grid can be laid at a distance of 1.5*1.5/3.0*3.0m. Each cross-shaped intersection serves as a connection point for a vertical ground body. Finally, the surface of the grounding grid is filled with fine soil.
The soil in saline-alkali areas contains highly corrosive substances. Therefore, metal materials are not generally used as grounding bodies in such environments. Non-metallic materials are very suitable for use here. Here is an introduction to the method of embedding expanded graphite in saline-alkali weathered stone geology. The geological conditions of weathered stone are that one type is mainly composed of completely weathered stone, and the other type is composed of a mixture of weathered stone and huge granite. The soil resistivity is above 2000 ohm. It is very difficult to make a ground network under such conditions. The construction difficulty for workers suddenly increases, and many colleagues are discouraged from this.
Here I will introduce to you the method to improve the difficulty of construction. Before construction, excavate and pour enough water. Because the structure of weathered stone is relatively loose, water can penetrate into the interior of weathered stone, and finally Let it soak for more than 12 hours. At this time, the strength of the weathered stone is only equivalent to the state of compacted sand, and it is easy to construct. At this time, dig a trench with a depth of 1.2 meters and a width of 0.2 meters. If you encounter a huge granite, you can bypass it and install it. At this time, install the expanded graphite grounding body horizontally, wrap the filler outside, connect the grounding bodies with flat steel, and treat the nodes with anti-corrosion treatment. Only a dozen expanded graphite grounding bodies can meet the technical requirements. Note that it is best to use fine black soil for backfill soil. If unconditional, you can also use excavated weathered stone. However, be sure not to use large pieces of weathered stone when backfilling. Try to use fine weathered stone soil, which must be compacted in layers. There is also a situation where the surface of the soil is 10 cm thick black soil, and underneath the black soil is iron sand of similar particle size. This is a very headache for making a ground network. Remove the black soil on the surface, dig out the iron sand underneath, and dig a 1.5-meter-deep pit for each grounding electrode. At this time, each pit is easy to collapse due to the looseness of the iron sand. If there is a baffle to block the surrounding iron sand, it is best to Well, if there is no baffle, just dig the pit larger. At this time, drill a galvanized iron pipe with a length of 1.5-2 meters and a diameter of 30 mm at the bottom of the pit perpendicular to the ground. It is very easy to construct on loose iron sand. Vertically connect the expanded graphite grounding body to the installed iron pipe, and make a horizontal flat iron connection 0.5 meters away from the ground. If you want to interconnect the cross points, the nodes should be anti-corrosion treated and directly backfilled with iron sand. The resistance value can meet the usage requirements.
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