Development of the monitoring system for instant displacement surrounding deep foundation pits

Displacement monitoring is one of the important measures to insure the construction safety of deep foundation pits.With regard to the problems and weaknesses of the traditional soil displacement monitoring system for foundation pit,a new remote monitoring system has been developed based on the principle of collimation measure.Semiconductor laser is used as its datum line. Its photoelectric transformation is realized by the matrix of light fiber and photodiodes.Single chip microcomputer is used to collect and preprocess the data.Digital signals get into the monitoring computer through a modem.Finally the displacement-time curve can be drawn on the computer.By means of the curve,the stability of the foundation pit can be evaluated.The precision of the system in use is 0.5 mm.The measure scope of the displacement monitor is 96 mm.The effective shot region of the laser is 100 m.