Geotechnical Survey

1. initial site investigation

The starting point for most geotechnical risk assessments is understanding the terrain and identifying any movement that has occurred. Using drone LiDAR, Diospatial captures the survey area to produce a LiDAR point cloud. The point cloud is then classified to filter out vegetation and produce accurate terrain data, including digital terrain models (DTM), digital surface models (DSM) and elevation contours.

To provide context to the site conditions, visualisation is important, in particular, visualisation of areas that are hard to access in person. For this, Diospatial captures high resolution imagery using a combination of drone and hand-held capture techniques, which is then processed in photogrammetry software to produce a high quality photorealistic 3D model and orthophoto of the site. The 3D model is interactive and enables close visual inspection without the need to visit site. The orthophoto provides a birds-eye 2D view of the site which is layered with elevation contours.

The spatial data captured by drone LiDAR and photogrammetry can then be used to complete further geospatial analysis including watershed analysis, volume measurements and feature extraction.

Conventional ground survey is used to capture site features and produce an accurate survey which can then be used to support design and planning of remediation works.

Additional spatial data can also be captured and produced to better understand the site specific conditions, including detailed inspection, movement monitoring, overhang mapping, and more.

2. Change detection & Monitoring

To understand how a geotechnical site is changing over time, change detection and monitoring solutions can provide detailed information of the extent of changes that are occurring in an identified geotechnical risk site.

There are two main ways that this can be achieved.

1. Ongoing monitoring using tilt sensors – set up in specific locations, these monitors provide real-time alerts of any movement that is detected.
2. Multiple repeat data captures – these can be completed over set intervals and compared to each other to better understand the extent of any movement and any risk that is present.

Once multiple captures of the site are available, displacement analysis can be completed to understand how much of the earth has been displaced. This can provide important information to geotechnical engineers as they plan and design remediation works.

3. Work-as-executed Survey post remediation works

Once any geotechnical slope stabilisation works are completed, a detailed Work-As-Executed survey can be completed. This provides a digital copy of the most current condition of the site or asset for owners and operators to keep as a record, and can act as a record for completion of remediation works by contractors.

Diospatial generates a digital twin of the site which is then used to digitise the constructed features of the site, including any rock fall netting, rock bolts, soil nails, retaining walls and existing asset features. The digitised features are then exported to drafting software where detailed WAE drawings are prepared.

Unlike conventional means, the survey and feature extraction is completed safely and efficiently in a virtual environment, reducing exposure of site personnel and reducing the disruption to asset operators.

APPLICATIONS OF geotechnical surveys

Diospatial’s geotechnical survey solutions can be used for a range of geotechnical engineering challenges, including:

• Risk assessment
• Geotechnical remediation design
• Geotechnical risk monitoring
• Coastal erosion assessment and monitoring
• Overhang identification
• Drainage effectiveness and monitoring
• WAE documentation of remediation works

DEliverables of Geotechnical surveys

Our team of expert data technicians develop a reporting solution that provides engineers and asset owners with the most insightful and actionable deliverables.

Depending on the information required for the specific risks associated with the site, several different deliverables can be produced. This may include, but is not limited to:

• Topographic survey, including digital terrain model (DTM) and digital surface model (DSM), elevation contours, watershed analysis
• 3D photogrammetry modelling digital twin
• Conventional survey with extracted features
• High resolution imagery
• Point cloud
• Orthophoto
• WAE PDF Drawings
• Live monitoring portal
• Volumetric analysis
• Change detection heat map
• Web based 3D model hosted on Pointerra, with all geospatial data