Geotechnical forensic investigation of a slope failure on silty clay soil-A case study

• Published in: Frontiers of Structural and Civil Engineering Vol. 14; no. 2; pp. 501 - 517
• Main Authors: NAVEED, Mohammad Abubakar, ALI, Zulfiqar, QADIR, Abdul, LATIF, Umar Naveed, HAMID, Saad, SARWAR, Umar
• Format: Journal Article
• Language: English
• Published: Beijing Higher Education Press 01.04.2020; Springer Nature B.V
• Subjects: Cities; Civil Engineering; Clay soils; Countries; Earthquakes; Electrical resistivity; Engineering; finite element method; forensic geotechnical investigation; Forensic science; Laboratory tests; Micro piles; numerical analysis; Qila Bala Hisar; Regions; Research Article; Runoff; Scanning electron microscopy; Seepage; Seismic activity; seismic loading; Sewage; slope analysis; slope failure; Soil investigations; Soil nailing; Surface drainage; Water seepage; X-ray diffraction; Peshawar Pakistan; Pakistan; finite element method; forensic geotechnical investigation; slope analysis; Qila Bala Hisar; numerical analysis; seismic loading; slope failure
• ISSN: 2095-2430; 2095-2449
• DOI: 10.1007/s11709-020-0610-y

Qila Bala Hisar is one of the noteworthy places of Peshawar, Khyber Pakhtunkhwa. The fort was constructed on a filled ground during the 18th century and it was renovated several times by the occupants ever since. Recently, due to an earthquake of magnitude 7.3, the upper part of the south-western wall of the fort collapsed. The collapse of the wall was attributed to the failure of the retained slope. This research was undertaken to characterize the slope material, study causal factors of failure and evaluate remedial strategy. The investigation involved conventional field and laboratory testing and geophysical investigation using electrical resistivity technique to evaluate the nature of stratum. Also, X-ray Diffraction and Scanning Electron Microscopy was used to study the slope material at a molecular level to evaluate the existence of swelling potential. The analysis has shown that excessive seepage of water caused by the poor maintenance of runoff and sewage drains is the causal factor triggered by the seismic event. A remedial strategy involving soil nails, micro piles and improvement of the surface drainage is recommended.