Results showed that AE can be considered as a viable method to predict the remaining service life of reinforced concrete structure.AcknowledgmentThe authors would like to thank Universiti Sains Malaysia selleck inhibitor (USM) for providing support through the short-term Grant (304/PAWAM/6039047).
Shallow-buried resources have been decreasing with the rapid progress in global economy. Thus, the exploitation of deeply buried resources has drawn interest from a number of countries. South Africa, Russia, India, and China have recently conducted a series of exploitations of deep mines with embedded depths of more than 1,000m. In China, the Jinchuan nickel mine, Tongling copper mine, and Dingji coal mine are more than 1,000m deep, whereas the Jinping II Hydropower Station is 2,600m deep.

The Kolar gold mine in India is 2,400m deep, and the deepest gold mine worldwide residing in South Africa is 3,700m deep. This series of new phenomena in underground engineering with increasing embedded depth has caused the emergence of a failure phenomenon called zonal disintegration. Shemyakin et al. [1] defined zonal disintegration as the alternated regions of fractured and relatively intact rock masses appearing around or in front of the working slope during the excavation of tunnels in the deep rock mass. This phenomenon has not been observed in shallow rock engineering. Moreover, zonal disintegration presents a serious hazard to the stability of surrounding rocks (Qian) [2]. Zonal disintegration in many deep tunnels has been monitored using the physical probe method.

Adams and Jager [3] were the first to observe such phenomenon by using a bore periscope at an embedded depth of 2,000m to 3,000m in the Witwatersrand gold mine in South Africa. He reported that zonal disintegration occurred when the tunnel was excavated either by drilling and blasting or the mechanized method. However, explosion was eliminated as the result of zonal disintegration after Shemyakin [1, 4�C6] explored zonal disintegration in Taimyrskii deep mine in Russia by using a resistivity meter. Zonal disintegration phenomenon differs from the engineering response in shallow rock excavation and as such cannot be explained perfectly under the framework of traditional rock theory. In accordance with the concepts of traditional continuum mechanics, the enclosing rock mass around a deep tunnel is divided into fractured, GSK-3 plastic, and elastic regions from the periphery of the tunnel to infinity. Zonal disintegration, a characteristic of deep rock masses, has been the focus of recent investigations.A number of experts have used various methods to explain zonal disintegration. Sellers and Klerck [7] indicated that the discontinued surface could be one of the derivations of zonal disintegration.