The main goal of this study was the detection of complex
surface and internal structures of limestone bedrock over
the entire area planned for urban development on the lower
Eocene plateau, west of Assiut, Egypt. A 2.5D shallow seismic
refraction survey provided sufficient resolution for mapping
faults and karst at the scale required for civil engineering
plans. "e 3D P-wave seismic velocity map was developed
from integration of a series of 2D spreads recorded along a
2D grid using only inline spreads.
A karstic limestone bedrock is interpreted across the study
area possessing several significant material property changes
that must be compensated for during engineering designs. It
was found that the P-wave seismic velocities of this bedrock
range from 2800 to 4500 m/s with depths to the bedrock
ranging from 3 to 35 m. Some of the karstic features of the
limestone bedrock associated with faulting were found. "e
locations of the subsurface karstic features, which are exposed
only occasionally in outcrops on the surface, must be considered
during layout and design of foundations for urban
projects associated with economic growth. Special care must
be taken during planning of heavy structures associated with
urban and industrial projects over these karstic limestone
bedrock to avoid collapse or failure of the buildings.
determines layer velocities and thicknesses, but also defines
depths to bedrock and major structural features critical for
civil engineering projects, such as construction of buildings,
bridges, tunnels, dams, highways, and other projects. In this
study, we found it especially useful for detecting karstic features
below the overburden and structures such as sinkholes,
cavities, faults, and pinnacled rockheads.
"e study area measures approximately 3 km2 (Figure 1).
"e site is located on a limestone plateau in middle Egypt
and is considered the best location for urban expansion and
construction of new suburbs and communities (Abdel Aati,
1995) for the following reasons:
1) "e site is located in a safe area, protected from the environmental
pollution from the Assiut cement factory.
2) "e area is extensive and distinguished by hard soil suitable
for the foundation and building.
3) "e area was not earthquake-prone, based on historical
observations.
4) "is area is rarely affected by rainfalls or flash floods.
5) "e abundant natural earth resources suitable for building
materials and stones, such as limestone, gravel, and sand
are quarried in the surrounding areas.