Field performance of concrete pipes during jacking in cemented sandy silt

Abstract

Although many field investigations into pipe-jacking installation have been reported within the literature, there are few reports on the rebar stress in jacking pipes. This paper presents the field performance of concrete pipes during the jacking carried out under the Guan River in Jiangsu, China. Rebar stresses at two wings (the left and right side), the top crest, and the base in the longitudinal and circumferential directions for four different pipes were monitored. The maximum rebar stresses during the jacking were 37.1MPa in the longitudinal direction and 36.6MPa in the circumferential direction. However, the maximum rebar stresses after construction were only 18.5MPa in the longitudinal direction and 20.3MPa in the circumferential direction. A normalized jacking force “α” is proposed to evaluate the additional rebar stress in jacking pipes. The range of α is from 0.04 to 0.25. The relationship between the rebar stress and the construction procedure is presented and discussed. An excessive jacking force, an alignment deviation or an increased penetration rate would generate a large incremental rebar stress.