الفهرس 
CHAPTER 1 INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 365 |  |  |
| | | from | 365 | | |
Abstract
The study area is situated to the northeast of Cairo City, between latitudes 30˚ 05’ N and 30˚ 30’ N, and longitudes 31˚ 25’ E and 31˚ 40’ E. It is bounded by the Cairo-Suez road from the south and covers an area of about 1250 Km2.
Two techniques were regionally applied in the study area, the gravity and magnetic studies, whereas other four techniques were locally conducted; the geological, geo-electrical, EM and shallow seismic refraction. The local part which occupies the eastern spot in the study area is situated between latitudes 30˚13’ 54.00’’ N and 30˚ 17’0.00’’ N, and longitudes 31˚ 35’2.40’’ E and 31˚ 40’0.00’’ E.
The main objectives of this work is to study the geologic setting of the area and use the integrated geophysical investigations to get an improved understanding of the structural trends delineation, the subsurface basement relief, detection of the thickness and resistivity of the subsurface layers and finally the calculation of dynamic and static soil/rock properties. These integrated geophysical investigations are achieved by applying several geophysical methods such as gravity, magnetic, geo-electric resistivity, EM studies, and shallow seismic refraction.
The constructed geological map reveals the fault regime in the study area in the form of fifteen normal faults oriented in the NE-SW and E-W directions with different configurations (fault pattern). Also, the geological map reveals that there are eight folds in the study area as follows: The first plunging syncline is located in southeastern part. The next three plunging anticlines; two of them are located in northwestern part and the third one is located in the southeastern part. The following three double plunging anticlines; two of them are located in the NW part and the third one located in the middle part of the study area. The last two non-plunging anticlines are located in southern part of the study area.
Moreover, there are six unconformity surfaces observed in the study area, an old regional unconformity between the Oligocene and Eocene formations just south of the study area. In addition, there are five local unconformities arranged from older to younger.
The gravity and magnetic techniques revealed that there are different faults dissecting the area in the NE-SW trend identical to the Gulf of Aqaba direction, NW-SE matching the Gulf of Suez, N-S matching the River Nile system, and E-W matching the Mediterranean tectonics.
The iso-apparent resistivity maps reveal that the main graben structure found in the study area forms the main wadi in the central part that is topographically low and directed in the NE-SW direction composed of sand and gravel of Oligocene age. This wadi is typically compared with the results of the other geophysical tools and surface geology with a good match.
Sixteen EM profiles were conducted in the SE-NW direction. Fifteen normal faults were detected from the results of EM studies. These faults are oriented in the NE-SW and E-W directions. They confirm the regional geological setting resulted from the constructed geologic map in the study area. It can be concluded from the results of the EM method that the area has been affected mainly by the Gulf of Aqaba as well as River-Nile system and Mediterranean tectonics.
Five seismic lines were conducted in the study area; each one contains five seismic profiles. Each seismic profile involves five shot records. from the results of seismic refraction interpretation and multichannel analysis of surface waves (MASW) at the new Al-Obour city, the smoothed inversion of the P-wave and shear-wave 2D velocity models with the help of the geological knowledge of the area, four normal faults (F2, F6, F14 and F15) were detected that cause an abrupt change in seismic velocities through these seismic lines with higher velocities belonging to Miocene Limestone opposite to lower seismic velocity values belonging to Oligocene sand and gravel.
The engineering-geological characterization was done through the calculation of dynamic and static soil/rock properties for civil engineering purposes.
The shallower part of the geological section in the study area contains five layers presented from the compressional (Vp) and shear wave (Vs) velocities models. Based on the created seismic velocities and the calculated bulk density values, the dynamic soil/rock geotechnical properties were calculated for each layer in the study area.
The vertical cross sections of the compressional (Vp), shear-wave velocities (Vs) and the calculated dynamic elastic properties show that: abrupt change in these properties due to the presence of normal faults form a structurally high horst block and Oligo-Miocene basaltic sheet.
The compressional, shear velocities and the calculated dynamic elastic properties maps were established for each layer: it was noticed that, there are high values in these properties at the SE and NW parts due to the presence of Miocene limestone, sandstone, and shale rocks, while there are lower values in the central part of the study area due to the presence of Oligocene sand and gravel rocks. Two normal faults creating a graben structure confirming the presence of the main wadi directed in NE-SW trend that matches the results obtained from iso-apparent electrical resistivity, EM conductivity and surface geological maps.
The static properties were calculated for some selected soil and rock samples in the study area.
The physical properties of rock samples were represented by the bulk density and porosity. The bulk density lower values related to the presence of highly fossiliferous sandy limestone and the higher values related to the presence of quartzite in contact with basalt. The porosity lower values related to the presence of highly fossiliferous sandy limestone and the higher values related to coarse ill-sorted sandstone.
The mechanical properties of rocks were represented by the uniaxial compressive calibrated from Schmidt hammer rebound numbers strength classified as medium to strong rocks.
The physical properties of soil samples were represented by bulk density and specific gravity. The bulk density values depend on the mineral composition and the degree of compaction of the sample.
The geotechnical parameters of soil samples were represented by liquid limit, plastic limit and free swelling.