Zak Davis, 36 years old and from Billinghay, Lincolnshire, was working on a small housing development just off Wragby Road, Bardney, Lincolnshire when the incident happened on 4 August 2011.
Mr Davis, described as a former England kickboxer, has had to give up the sport as a result of the injuries sustained.
Nottinghamshire engineering company was today fined for the incident which saw 36-year-old Zak Davis, of Billinghay, Lincolnshire, buried up to his waist when a trench collapsed.
Mr Davis was laying drain pipes in a trench that was being dug by an excavator. It had been raining heavily during the day. While he was in the trench the digger operator noticed the walls beginning to crack and shouted a warning, but before Mr Davis could escape he was hit by the falling material, including a large lump of concrete, and was pinned down by his legs.
He dislocated and fractured his hip socket and shattered his pelvis. He needed 10 hours of surgery and is still off work.
An investigation by the Health & Safety Executive found that contractor Phil Watson Civil Engineering Ltd had failed to assess the ground conditions and the effect that the rain would have, and failed to install measures to prevent a trench collapse.
The company, of Victoria Street, Shirebrook, Mansfield, Nottinghamshire, pleaded guilty to breaching Regulation 31(1) of the Construction (Design and Management) Regulations 2007. Lincoln magistrates today fined the firm £10,000 and ordered it to pay full costs of £2,141.
After the hearing, HSE inspector Tony Mitchell said:
"Excavation work is a high risk activity, but the risks are foreseeable and preventable.
"The site had previously been a farm. It had been demolished and the rubble spread on site as top fill. The subsoil beneath it was predominantly compacted sandy soil, so the ground conditions were poor. However, this was not properly identified as high risk before work started, the rain made the soil structure more unstable and the trench collapsed because it was not sufficiently supported.
"This incident could have been prevented by the use of mechanical trench supports or by sloping the trench sides further. Instead, a man has been left with life-changing injuries."