With the development of high-rise buildings in city, the demand of air-defense engineering, underground garage and basement is increasing, the construction of foundation pit is more and more and excavation depth is deeper and deeper. It has many uncertain factors only depending on geological exploration data and experiment parameters. So the monitoring of soil property, load condition and construction environment, etc, has become an essential link during excavation construction, which is also a necessary measure for correct guidance and ignoring accident.
1.The necessity of monitoring.
Theoretical research and engineering practice prove that theory, experience and monitoring should combine together to guide foundation pit’s design and construction.
Because of indifference of monitoring during construction, there are many serious engineering accidents and casualties, such as: unstability of foundation pit structure, cracks of surrounding buildings and destroy of underground facilities, etc. So, as for over 4m-deep foundation pit, monitoring becomes more and more important. At the same time, it will help to master the regulation of surrounding rocks’ activity and provide support parameters for anchor bolt's load change, ensure security of construction and gather experience for more complex conditions.
2. Monitoring contents.
Foundation pit construction demands certain safe and efficient retaining structures to block water and soil. The monitoring contents are mainly manifested in anchor bolt’s anchoring force, roof separation condition, surface displacement, deep displacement and anchor bolt’s load, etc. Besides, construction environment should be known in advance, such as: underground soil layer, pipelines, facilities and surrounding surface structures. Discovering and forecasting occurrence and development degree of dangerous situation, then adopting secure remedial measurements in time.