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
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:
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).
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.
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.
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.
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 management is based on gINT®
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.
|Seismic Hazard Evaluation
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.