Abstract
Detailed field geological, geoelectrical, hydrochemical, and microbiological studies were executed in the Wadi Hof area, southeastern Cairo, Egypt to delineate the causes of landslides along the train pathway between the eastern Wadi Hof camp and the western clay quarry. The area under consideration is of a gentle slope from east to west. The Eocene limestone rocks constitute the most common outcrops. Structurally, the investigated area was affected by faulting. Geophysically, 1D Schlumberger Vertical Electrical Soundings in addition to 2D Wenner Electrical Resistivity Tomography (ERT) techniques were performed to characterize the shallow subsurface implications. Eight Vertical Electrical Soundings were measured along with two main profiles-oriented northwest-southeast directions. A Schlumberger configuration with electrode separation starting from electrode separations (AB\2) = 1.5 m. to AB\2 = 200 m. was applied. Three 2D Electrical Resistivity Tomography profiles crossing the train pathway were constructed in a nearly east–west direction. The 1D inversion is applied using WinSev3.4 software and the 2D-ERT profiles were computed using the RES2DINV computer software. Moreover, hydrochemical and microbiological investigations in the form of water samples analysis were conducted east and west of the train pathway. The hydrochemical and microbiological characteristics of the analyzed water found that the water origin is different on the sides, east and west of the railway tracks. The integrated interpretations indicate that the study area consists of three main rock units; surface marl, calcareous sand, and, finally, clay to sandy clay units. The water originates from the Eocene limestone aquifer east of the train route directed towards the clay quarry west of the train path. Additionally, the landslides apparently result from the swelling of thick clay layers which leads to subsequent railway destruction shortly thereafter.
Highlights
Geoelectrical, hydrochemical, and microbiological studies were executed in Wadi Hof area, southeastern Cairo, Egypt to delineate the causes of landslides along the train pathway between the eastern Wadi Hof camp and the western clay quarry
The present work aims to find out the water origin that has collected at the floor of the clay quarry to the west of the train pathway, and led to landslides and damage of train path trajectory between the eastern Wadi Hof camp and western clay quarry, as well as, to shed the light on the geological conditions prevailing in this particular area
By discussing the results of geophysical studies in the study area, it was noticed that there is no contention in the sequences of geoelectrical units horizontally or vertically east and west of the railway tracks, in addition to the presence of a large thickness of the clay, it led to its saturation with water and resulted in landslides along the railway tracks
Summary
The present work aims to find out the water origin that has collected at the floor of the clay quarry to the west of the train pathway, and led to landslides and damage of train path trajectory between the eastern Wadi Hof camp and western clay quarry, as well as, to shed the light on the geological conditions prevailing in this particular area. The study area is located to the east of the River Nile, about 16 km to the southeast of Cairo with an average elevation of about 50 meters above mean sea level. It extends between latitudes 29o54 × 31.5ʺ and 29o54 × 57.5ʺ North and longitudes 31o18 × 07.1ʺ and 31o18 × 46.1ʺ East (Fig. 1). The quarrying activities in the western parts of the train railway play an important role in the instability of the Middle Eocene rocks slopes which represent potential sites of slope failure (Abd El Gawad, 2020). The field investigations showed that a considerable landslide under the train pathway and on the floor of the clay quarry in addition to several water pools are distributed randomly (Fig. 2)
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