The Fourth Tidal Wave of Geotechnical Engineering

Human history has witnessed several tidal waves of geotechnical engineering exploitation. The first one can be traced back to the early days of human history, when human beings lived in caves so as to be sheltered from wind, snow and storm, and the teeth and claws of beasts. During the Industrial Revolution, the advent of the second tidal wave was announced by large- scaled constructions of mine works, urbanization of capitalist countries symbolized by the underground embedment of such municipal engineering facilities as drainpipes and flow pipes, and the building of urban subways. Meanwhile, underground fortifications and hydropower stations were greatly developed. The third tidal wave of geotechnical engineering is characterized by the extension of human activities to underground, which result in constructions of underground commercial streets, underground parking lots, and various underground recreation and sports facilities such as art exhibition house, music hall, gymnasium, swimming hall and skating yard. Since the end of the twentieth century, the upgrade and development of the fourth tidal wave has been promoted by formulation of continuable development strategy by the United Nations and each country in the world and the heightening of people’s sense of environmental protection and their awareness of the importance of ever lasting facilitation of resources. The characteristics of the fourth tidal wave of geotechnical engineering are the improvement of urban environment and the protection of natural ecological environment. The high waves of geotechnical engineering rise one by one. The later waves do not substitute or exclude the former ones but improve and perfect them. The construction of Underground municipal works and subways during the second tidal wave have been continuing in the 3rd and 4th wave, of course, in a higher level. The construction of underground commercial streets, garages and various recreation and sports facilities in the 3rd tidal wave will go on in the 4th one and in more cities. Over the past 30 years, excavation techniques for tunneling in solid rock or in complicated geology conditions have made great progress. The solidity of rock, which used to be regarded as a disadvantage, turns into advantage, for it helps increase the span of Underground cave and enable rock to stand higher speed of tunneling. Since 1990s, some advanced techniques, such as the directional and orientation technique of underground construction (DOT), the underground prospecting technique (UPT) and the automatically controlling construction technique of tunneling and lining, have been applied to practice in varying degrees. DOT is represented by laser guiding technique and GPS orientation technique, while UPT is represented by remote sensing technique and by through-ground radar technique. As a result, the 4th tidal wave is becoming wider in scope, larger in scale and higher in level.