Page 134 - Handbook of Materials Failure Analysis

130 CHAPTER 6 Failure analysis of concrete sleepers/bearers

(a) (b)

(c) (d)

(e) (f)
FIGURE 6.4
Crack of the concrete bearer under the rail pad. (a) Geometry of Clyde 700 diamond (looking
toward Sydney). Poor line smoothness (lateral alignment) and vertical rail dip can be
observed at the diamond. (b) Ballast pulverization at k-crossing, black greasy material was
collected at fastening area. Note that there is a small gap between ballast and the ends of
bearers subject to high-impact force due to some small dilation of ballast. (c) Ballast
pulverization at country-end v-crossing. (d) Crack of the concrete bearer under the rail pad.
(e) Cross profile of ballast and subgrade at the country-end v-crossing at rail seat area.
Ballast contamination can be observed. It is noted that there is a high level of ballast
densification due to high-frequency loading. (f) Cross profile of ballast and subgrade at the
country-end v-crossing at middle span of bearer (1 m deep excavation).