This rule is applicable to the horizontal displacement and vertical displacement monitoring of foundation pit engineering in general soil and soft soil buildings. eye

The purpose is to grasp the influence of foundation pit construction on adjacent buildings, play the role of early warning and forecasting in time, provide scientific decision-making basis for deep foundation pit construction, ensure construction safety and reduce the adverse impact on the surrounding environment.

2. Instruments and materials

Total station, level.

Others: tripod, prism, tripod, invar ruler, etc.

3. Monitoring principles and methods

In order to ensure the unity of all monitoring work, improve the accuracy of monitoring data and effectively guide the whole project construction, the monitoring work adopts the principle of overall layout and layered network distribution. That is to say, a unified monitoring control network is laid first, and then monitoring points are laid on this basis.

3. 1 Vertical displacement measurement of monitoring points: According to the requirements of the national second-class leveling standard, in the past, the vertical displacement monitoring was to measure the elevation of each monitoring point through a second-class leveling closed or attached route between the base points of the joint survey, and the initial elevation of each monitoring point was measured twice (twice on average) in the early stage of the monitoring project. The difference between the current elevation and the previous elevation of a monitoring point is the current vertical displacement, and the difference between the current elevation and the initial elevation is the cumulative vertical displacement.

3.2 Measurement of horizontal displacement of monitoring points: Axis projection method is adopted. Choose a stable reference point A and B at the distance between the two ends of the survey line, set up a theodolite or total station at the point A to orient the point B, and connect the points A and B as reference lines. During observation, read the value of vertical distance e from each monitoring point to AB baseline on the instrument. The current e value and initial e value of a monitoring point are the cumulative horizontal displacement of the point, and the initial e value of each deformation monitoring point is averaged twice.

4. Layout principle and setting of monitoring points 4. 1. Layout principle

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