[Abstract ] With the development of urban construction, the price of land in all the urban centers has become increasingly expensive. Seeking more space in the air and to the deeper underground has become the builder’s common means of pursuing economic benefit. In Shenzhen, Guangzhou, Dongguan and other places, the excavation of the depth of foundation pit is becoming deeper and deeper, from the initial 4-8 meters to more than 20 meters now. Due to the nature of the underground soil, loading conditions, the complexity of the construction environment, there are often many uncertainties while choosing the programs of design and construction solely based on the information of geological survey and the parameters of geotechnical test, especially to those large and medium-sized complex constructions or those strict environmental requirement project. The monitoring of the deformation of soil properties, the environment, the buildings nearby and the underground facilities has become the essential process in the project construction. At present, the foundation pit monitoring, project designing, constructing are classified as the three essential factors. The foundation pit monitoring will surely be the key to ensure the quality of deep foundation pit and safety, and an important part of the project construction.
