The pipes can be divided into four kinds based on their cause of formation, namely pipes formed by the animals, by the roots of plants, by the cracks of soil and by the soil water movement.
The cathodic protection combined with the insulating coating is applied widely to the protection on the outside of the pipes in soil.
绝缘涂层加阴极保护被广泛应用于地下埋设管道的外壁防腐。
3
When the resistive moment of surrounding soil is less than the torsional moment of eccentric jacking force, stability failure of pipeline occurs and pipes deviates from the designed axes.