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Geophysical Surveys

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Ground Probing Radar Survey

Ground Probing Radar (GPR) is a high resolution, field-portable geophysical method that produces graphic sections of subsurface structure. Site investigation applications include the accurate location of voids and buried obstructions, mapping of subsurface soil and rock interfaces and buried archaeological structures; identifying ancient landfill, and detection of buried hazardous waste. GPR surveys are non-destructive, revealing detailed information on subsurface ground conditions without drilling or excavation.

Applications:

1. Investigates thickness and internal structure of floors and walls.
2. Locates internal steelwork in concrete such as rebar, girders & cable ducts.
3. Identifies ties between courses of brickwork.
4. Locates voids, cracks and delaminations in all types of materials.
5. Finds zones of water penetration and corrosion within defective concrete.
6. Determines thickness of brickwork and masonry construction layers.
7. Locates buried voids & cavities.
8. Determines depth of bedrock and overburden thickness.
9. Finds buried underground storage tanks (USTs) and drums.
10. Tracks non-metallic culverts and sewers.
11. Maps buried foundations and other obstructions.
12. Defines extent of ancient landfills.

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Void Dectection

Along with the experience of utilizing Ground Probing Radar to detect voids for many years, we have further developed leakage detection by Ground Probing Radar. Since the change of radar propagation velocity reflects the soil saturation with leaking water. Such method could provide valid data for leak cases that are difficult to be located by conventional method as it is independent of the pipe material. Local successful job reference is available

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Borehole GPR survey

It is often challenging for underground construction in congested underground condition. By using borehole GPR, we offer Precise Underground Locating Survey. It has low disturbance with high accuracy on underground obstruction and subsoil feature. It uses modified GPR antenna to detect object through the changes of dielectric constant. Depending on soil condition and underground salinity, it gives pipelines location depth of 15m up to 150m and a penetration radius up to 3m.

Applications include:

  1. Determine depth of bedrock and overburden thickness.
  2. Finds buried underground storage tanks (USTs) and drums.
  3. Defines extent of ancient landfills.
  4. Locates deep buried voids & cavities.
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Seismic Refraction Survey

For ground investigation and construction industries, Waterland provides an innovative Seismic Survey to determine underground soil and geological structure properties. Comparing to traditional trenching, Seismic Survey fits well in urbanized area as it does not require surface destruction in deep soil investigation. Moreover, it has a small surveying footprint with a short period of time. The in-site utilities can also be in-service while there is an ongoing survey. Depending on site situation and client requirement, we provide three different applications of seismic surveying: MASW, Refraction, and Reflection. All the applications require an active source like a weight drop to generate seismic wave. In addition, all methods work when underground water presents.

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GCO Probe Test

The GCO probe test is used for assessing the depth and degree of compaction of buried fill, making comparative qualitative assessments of ground characteristics, and in supplementing the information obtained from trial pits and boreholes. Probe results are normally reported as the number of blows per 100mm penetration.

The primary use of dynamic probing is to interpolate data between trial pits or boreholes rapidly and cheaply. Therefore, probing should first be carried out adjacent to a trial pit or borehole where ground conditions are known, and then extended to other areas of the site.