Quick Search

433 Failure of pre-cast concrete 'L' shaped retaining wall

Report ID: 433

Published: Newsletter No 35 - July 2014

Report Overview

A recent incident occurred on a site, where a temporary pre-cast retaining wall failed leading to a pile of clay approximately 3m high spilling through the wall.

Report Content

A recent incident occurred on a site, where a temporary pre-cast retaining wall failed leading to a pile of clay approximately 3m high spilling through the wall. The fill was fortunately prevented from falling further by a site boundary hoarding. This was located immediately adjacent to an operational railway, and had it failed the hoarding and the fill could have fallen into the path of an oncoming train, potentially injuring railway staff and customers. The reporter says that failure was at the bend in the L shape, suggesting that the overturning moments caused by the clay back-fill exceeded the capacity of the precast units. The applied moments could have temporarily exceeded the design moments due to the recent periods of sustained heavy rainfall leading to saturation of the stored clay material. The reporter says that similar incidents have occurred on other sites.

 

Comments

There have been failures over the years where temporary stability has been inadequate. Here, whether the designer was fully briefed, or whether the design limitations were spelt out, but ignored, we do not know. Both are vital to a safe design as is a design check. Again a suitable risk assessment is vital especially where there is the possibility of a small failure leading to major consequences, such as a train derailment. The HSE publication:   Preventing catastrophic events in construction (2011) examined these ‘low probability but high-consequence’ safety hazards by looking at:

• the types of catastrophic event which have occurred or which might occur during construction;
• the reasons for occurrence when there have been (or could have been) catastrophic events during construction, including an examination of the underlying factors;
• the controls which should contribute to an avoidance of a catastrophic event; and
• where the UK construction industry could improve.

Sometimes structural elements simply topple under unexpected load. One case involved tall slender I bridge beams that fell over under wind before a concrete deck was added. In another, in a shopping centre, something being temporarily leant against a wall just toppled over and killed a child. CROSS has reported on posts being lifted into position and at risk of toppling before being fixed to holding down bolts. 324 Lack of experience on steel column erection

 


Previous page

Email Updates

How to Report

Online submission:
Submit by post: