Lateral soil pressure induced failures

Abstract

In early 1970s in Malaysia many piled bridge abutments on soft ground experienced failures during earth embankment construction. The Public Works Department (PWD) issued a directive to construct the earth embankment first with surcharge load before the piled bridge abutment was built. This simple procedure and precaution eliminated the incidences of bridge abutment failures for at least 10 years. In 1980s a bridge abutment failed again with an embankment height of 7m under similar soft ground conditions when the PWD directive was not followed. The concept of construction of the embankment first was principally to eliminate significant settlement and lateral movement of the soft ground before the construction of the piled bridge abutment. Damages to piles and foundation can occur as a result of lateral soil pressure and soil movements. This aspect of risk and mitigation of failure has often time been ignored by the designer and supervising engineer alike. In 1993 the 12-storey Block 1 Highland Towers collapse was also due to the lateral soil pressure exerted by the culmination of falling earth fill from retrogressive landslides behind the building causing the old used rail piles that was used as building foundation to yield and sheared off. This paper examines some recent cases of failures due to lateral soil pressure and their rehabilitation. Vacuum consolidation offers good remedial solution to unstable ground with bridge abutment.