Chinanews, Hong Kong, Dec. 6 – Since China built the Three Gorges Dam with high-grade concrete, it might extend the service life of the dam to five hundred years instead of the 300 years as engineers once expected, said Wang Dianchang, senior engineer at the State Council Three Gorges Dam Construction Committee, the Hong Kong-based Ta Kung Pao reported.The service life of the dam depends largely on the materials that were used to build it. After completion, minor maintenance work might be done at some parts of the dam to make it more durable. However, this will not affect the general service life of the dam. Based on the current situation, we expect that the dam can be used for more than five hundred years, Wang said.Before building the dam, engineers gave full consideration to the choice of the site of the dam and the site's geological conditions. The construction process also went on smoothly. All this will help greatly to prolong the dam's service life. The Three Gorges Dam is built on granite rocks and every square centimeter of such rock can sustain 1,000 kilograms of pressure on it. This means that the Three Gorges Dam is built on a very firm basis, said Zhang Shuguang, deputy chief engineer at the China Three Gorges Project Corporation.At the same time, it should be noted that no big earthquakes have ever occurred near the dam's area. According to experts' calculation, none of the earthquakes that may occur in the Three Gorges Area will be stronger than level-6 on the Richter Scale and the dam is designed to survive level-7 earthquakes on the Richter Scale. This can ensure that the dam can survive even the strongest earthquake that might possibly occur in the area.