Study On Testing Technology Of Anchor Cable Corrosion

Pre-stressed anchor cable, as unique effects, simple process and significant economic benefits, is widely used in the rock, dam foundation, slope, underground caverns and other areas of geotechnical engineering. The structure of anchor cable was marked by: having strong hidden and high pre-stressing, and generally used in the projects of higher security level. As the surrounding rock and soil moist environment, and other complex factors as possible erosion of media and stray current, etc. Anchorage cable under the protective system in the long-term use will gradually aging, injury or damage, coupled with self-protective systems of the anchor are imperfect and other factors, resulting in shortage of anchor durability have occurred, thus taking security risk for project. Thus the status of non-destructive testing anchor corrosion's condition becomes extremely important.For the problem of corrosion in pre-stressed anchor cable, analyzing the corrosion mechanism and the impact of corrosion on anchoring structure with durability, focusing on the corrosion of non-destructive testing methods, using Ohm's law to detect the resistance value of anchor protective system, conducting a theoretical analysis and field tests, showed that the method is feasible. The results achieved are the following:①The corrosion mechanism of pre-stressed anchor cable have electrochemical corrosion, stress corrosion, hydrogen embrittlement, stray current corrosion and other corrosion failure mechanism such as chemical, biological, intergranular and debris corrosion. The main factors that lead to anchor rusted have external environment, the composed material and type of anchor, and the construction quality, materials fatigue etc.②The corrosion damage morphology of pre-stressed anchor cable are mainly uniform corrosion, pitting, partial dissolution, intergranular corrosion, cracking, these are resulting from different factors contribute to corrosion. In the anchorage section, rusting makes bond strength lower between anchorage cable and grouting body; in the free section, rusting make plastic strain of strand worse, elongation reduced, the nominal yield strength, the nominal ultimate strength, and the nominal elastic modulus decreased rapidly with increasing the amount of corrosion.③For the structural design characteristics of pre-stressed anchor cable, proposed that through non-destructive testing the integrity of pre-stressed anchor cable protective system, to indirectly reflect the anchorage cable of the rust situation.④Using Ohm's law for detecting the resistance value of the anchorage cable protective system, to characterize the integrity of it. Smooth tube and corrugated tube are insulation materials, when it's intact, the measured resistance value will be very significant; when there is broken, the current will go through the rupture, and the resistance value will be obviously smaller.⑤In practical projects, testing the integrity of the protective system methods are single-anchor detection method, movable detection method and around-type detection method. Data analysis and processing mainly make use of comparative law, comparing the resistance of actual anchor protective system, maybe setting testing anchor to get contrastive resistance of destructive protective system, so as to contrasted with the actual anchor, comparing data on the differences, as it, classifying the level of integrity protective system, that can be divided into good or bad.