An investigation of the durability of the soil nailing method

It is not too much to say that the soil nailing has been applied to permanent slopes without verifying its long-term durability. Therefore, to investigate its long-term durability, we checked the stability of nine slopes, which were constructed about 10 years ago, making reconnaissance of them, and carried out the examination of the corroded condition of reinforcing bars collected by means of over-core boring, the material testing and so on. The corroded area ratio and the depth of corrosion were measured. In addition, a tensile test of the same reinforcing bars was carried out. As a result of of the authers investigation of the corrosion of reinforcing bars, the information suggesting that the following two factors of the cause of corrosion were obtained; at first, corrosion due to insufficient injection of grout into the part around the top of a reinforcing bar, secondly, corrosion due to insufficient grout cover in a deep part and insufficient injection of grout into such part.