Checking Integrity of Bored Piles Using Two Methods: Low Strain Method and Cross-Hole Sonic Logging - Experience of Application

Abstract

At present, in Astana city is going on works by construction public transport system LRT (Light Railway Transport). LRT is an overhead road with two railway lines. The first stage of construction is including construction of overhead road (bridge) with 22,4 km length and 18 stations. The foundation of bridge is the bored piles with cross-section 1.0÷1.5 m and length 8÷35 m. Design bearing capacity of piles is 4500÷8000 kN. For boring soil using Chinese drilling rigs Zoomlion without casing. To maintain the walls of boreholes in sand and gravel soils using polymer slurry. In these conditions, very important to control integrity of concrete body of each bored piles. For checking integrity applying two methods - Low Strain Method and Cross-Hole Sonic Logging. This paper aims to to discuss the advantages and disadvantages of each method using the examples of a real application.