ABSTRACT:

Shear strength of clays will generally increase with consolidation under load. Large embankments on soft clays can be constructed by adopting a staged construction approach utilising the strength increase associated with consolidation. This paper presents a case history of a staged embankment construction carried out for the approach embankments of the My Thuan Bridge over the Mekong River, in Vietnam. The site of the My Thuan Bridge is underlain by soft clay deposits about 14 m to 18 m thick on the north and south sides of the river, respectively. Approach embankments about 7.4 m high with a 1.5 m surcharge were constructed at the site. The embankments were instrumented with inclinometers, piezometers, extensometers and survey monuments to assess the performance of the embankment during staged construction. Cone penetrometer tests and field vane shear tests were carried out after Stage 1 consolidation to assess the increase in shear strength and the stability under Stage 2 fill placement. T The increase in shear strength was also assessed in terms the measured settlement and applying soil mechanics theories.

BACKGROUND

The My Thuan Bridge site is located along the northern arm (Tien Giang branch) of the Mekong River, about 125 km south-west of Ho Chi Minh City. The bridge is a cable stayed bridge with a 350 m main span, 150 m side spans and 11 viaduct spans of 40 m on each side. The design road level at the middle of the main span is about 40 m above the high water level in the river. Approach embankments about 7.4 m high with a 1.5 m surcharge were constructed on each side. The bridge site is located on the Mekong River flood plains and comprises recent Quaternary age deposits to considerable depth.

This content is only available via PDF.
You can access this article if you purchase or spend a download.