Field of Expertise

Performing geological and geotechnical surveys as part of the overall design of roads, dams and tunnels. The surveys include analysis of available geological data, field mapping and site investigations. Consultancy services are provided for environmental reviews and master plans. The field findings are processed in the office using advanced computer software, thereby generating a high-quality final product. The reports include graphical presentation (computerized maps, slope stability analysis, borehole logs), volume calculation for earth works and management of the geotechnical database (gINT^®).

GGS’ strong background in rock mechanics and its experience in performing laboratory tests are applied in the following fields:

Slope Stability
Evaluation of rock slope instability is based on statistical analysis of the discontinuities orientation using Dips software (Rocscience^®). Evaluation of the safety factor is based on the principals of Block Theory. RocFall software (Rocscience^®) is used for risk assessment of falling rocks considering slope geometry. Back analyses of slope failure were applied in the Arad phosphate mine. Risk assessment of falling rock was carried out for the Cross Israel Highway based on the principles of the RHRS (Rockfall Hazard Rating System).

Tunneling
Rock mass classification based on common methods (Q, RMR), and additional evaluation of rock mass based on the structure of rock and empirical failure criterion (GSI). Geological supervision (well sitting) throughout the site investigation. Geological monitoring during the construction, with follow-up documentation of the rock mass (Hadid Tunnel). GGS enjoys professional relations with international firms, participates in conferences, professional courses and site visits for projects located abroad.

Field work
The basis for reliable geological interpretation is acquaintanceship with the site, the outcrops and the relations between rock units. The fieldwork includes mapping of rock units, location of fault lines and accurate measurement of discontinuities orientation. These details are all marked in relation to their location in the field using a GPS device, which enables rapid transfer of data to the computer located in the office. The aim of site investigations is to fill in gaps in the information, to confirm or deny primary assumptions, and to sample the rock mass in order to perform laboratory tests.

Drilling
Sub contractors perform the drilling while GGS provides the professional guidance. The drilling process comprises four stages (PMSR):

• Planning – determining the amount, locations and depth of drilling according to project requirements and complexity of the geological information. The exact location of a borehole is determined according to accessibility in the field.
• Management – from the first stage of receiving all the approvals and coordination with the authorities through supervision of construction of roads in the field.
• Supervision – geological supervision (well sitting) throughout the performance of drilling, writing up field logs, storing samples in core boxes and supervision of in-situ tests. Long term monitoring to record changes in ground water level and earth movement.
• Recording – entering the field data into the geotechnical database in the office (gINT^®), production of borehole logs and cross sections. The data can be examined and compared with other data from previous site investigations.

Laboratory Tests
The laboratory tests are performed by approved laboratories according to acceptable standards and specifications. GGS provides instructions and guidance for test procedures. The test program is adapted to meet project requirements. The test results are presented in a clear manner including, graphs and pictures of samples.

Geotechnical Database
Geotechnical database management is based on gINT^® and Autodesk® MAP. gINT^® - Geotecnical Integrator software facilitates the recording of all field data and laboratory tests. Autodesk® MAP allows the creation of interactive maps with links to the geotechnical database and GIS capabilities.

GGS provides geological reports for evaluation of seismic hazards. In complex projects, the work is performed in conjunction with government institutes such as GSI (Geological Survey of Israel) and GII (Geophysical Institute of Israel).
The African-Syrian fault system (Dead Sea Rift in Israel) is located along the eastern border of Israel. Dozens of seismic events along this fault are recorded every year. In the past, some of these events caused the destruction of cities such as Tiberias, Beit Shean, Sefad and Ramla. Seismic hazard evaluation is an essential component in designing new major plans and projects in sensitive zones (Qiryat Shemona). The updated Israeli standard IS413 “Design provisions for earthquake resistance of structures” stipulates that a geological report is required because of the risk level when public buildings are to be built in an area with a seismic coefficient greater than 0.15 and/or in the vicinity of a suspected active fault.