With more large-scale urban developments planned and implemented, the scale and depth requirements of the foundation pit are increasing. Real-time monitoring systems play a significant role during the foundation pit excavation process, providing for the operator real-time data such as the deformation and structural condition of foundation pit, to avoid the occurrence of onsite accidents.

When compared with other monitoring methods, ZHYQ real-time monitoring system boasts extremely high accuracy and has the advantage of being more adaptable and less affected by variable weather conditions.

Sensor distribution and the choice of system model can be tailored to suit various depths and scale of the foundation pit. All sensors used are recommended to be deployed before construction.

Foundation Pit Structure Support Monitoring

Deep horizontal displacement
Automatic inclinometer is often used to monitor the internal displacement of rock and soil, which is the most direct means to monitor the deformation of the foundation pit retaining system. It is generally arranged in the central section, the corner and the representative sections around the foundation pit. To truly reflect the displacement of the retaining wall and the stratum, the buried depth of the survey tube should be failsafe.

Internal force around the retaining wall
The internal force monitoring points of the retaining wall should be arranged in the sections of the retaining wall where the extreme bending moment occurs. It is suitable to choose the midpoint of the two adjacent supports of the retaining wall and the section with larger excavation depth. In the vertical direction (monitoring section), the monitoring point should be arranged at the support and the middle part of the adjacent two layers of support.

Support the internal force
Different monitoring sensors are selected according to the type of supporting rod. For concrete support, surface strain gauge is widely used. For steel support rod, axial force gauge – also known as reaction force gauge – or surface strain gauge, can both be used for monitoring point.

Anchor internal force
The internal force monitoring points of a bolt should be selected in the representative position with a large stress, and the monitoring points should be arranged in the middle of each side of the foundation pit, the corner and the section with complex geological conditions.

Vertical column displacement
The vertical displacement of the column, also known as settlement or uplift, has a great influence on the axial force of the support. There will generally be large mechanical operation or vibration around it. Dynamic level can be used to arrange monitoring points in the parts of the column with large stress and deformation and ones prone to differential settlement.

Lateral earth pressure around retaining wall
The lateral earth pressure monitoring points of the parapet wall should be arranged in areas with great changes in stress and soil quality or other representative parts. There should not be less than two monitoring points on each side of the foundation pit in plane layout.

Monitoring of surrounding structures (building settlement, tilt and crack monitoring)

Settlement Monitoring
According to the survey of the surrounding buildings, determine the location and number of measuring points. ZHYQ Monocrystalline Silicon Hydro Leveling Sensor can be used in the corner, column, shape prominent sections and more sections of the two sides of the layout of measuring points, to fully reflect the uneven settlement of each part of the building as far as possible.

Slope Monitoring
ZHYQ Angle sensors can be used to arrange the building corner, deformation joints on both sides of the load-bearing column or wall.

Crack Monitoring
Representative cracks should be selected for the monitoring points of building cracks and surface cracks. When the original cracks increase or new cracks appear, monitoring points should be added.

Underground pipeline monitoring
Pipeline monitoring points should be set up according to the construction duration, type, material, size and current situation of pipelines. Direct monitoring points can be set up for water supply, gas, heating and other pressure pipelines. In places where direct monitoring points cannot be buried, indirect monitoring points can be utilised.

Monitoring of surrounding surface subsidence
The monitoring points of vertical surface displacement around the foundation pit should be located in the middle of the pit edge or other representative parts according to the monitoring section.

Other monitoring

Porewater pressure
ZHYQ osmometer can monitor the seepage water pressure inside the foundation pit. It is generally placed in the representative parts of the foundation pit with large stress and deformation.

The underground water levels
Foundation pit groundwater level monitoring detects the impact of precipitation on the surrounding environment. The water level meter should be arranged along the periphery of the foundation pit and the protected object or between the foundation pit and the protected object such as the water level monitoring points of adjacent buildings, important pipelines or crowded pipeline layouts.