Expert Witness Experience in China
Earlier this decade, I was working as Engineering Manager in a major project construction facility on the north coast of China. The Project was to complete the final detail engineering design, and to carry out full fabrication of the Modules for the process plant for a nickel mine development under way in New Caledonia. The Modules were of steel frame construction, having typical plan areas of 40m x 30m, and with heights varying to over 40m. There were 15 Modules constructed, with average weight of each Module, including all installed equipment, of close to 1,000 Tonnes.
The Module Fabrication Yard is located on the shore of Jiaozhou Bay, a 360 square kilometer tidal bay opening onto the Yellow Sea. The Yard has been constructed mostly on reclaimed land, formed with imported crushed rock and fine soil material. Observation of site works in the Yard showed that the rock and gravel used in the land reclamation works was not 'well graded fill' and so not well compacted. This Fabrication Yard occupies a strategic coastal location, and has a high political profile within the Chinese Government.
At the start of construction, there was no purpose constructed sea wall along the shore side of the Fabrication Yard. The rock and gravel reclamation material was simply sloped down into the bay, extending down to the natural sea bed, some 6 to 8 m below high water level. The first Module to be constructed was located less than 10m from the top of the reclaim embankment along the bay shore line. This module had a plan area of 40m x 30m, and six floors in height, each floor being over 5m high.
Dimensional control of the Module construction was critical, as the fit together tolerances were of the order of a few millimetres over final assembled project. Dimension control included surveying the level of the Module column footings, which were required to be exactly level with each other, and with zero tolerance for differential settlement. A typical Module could have up to 30 individual footings.
As construction of the first Module progressed to the first floor level, the foundation surveys highlighted differential settlement of more than 25mm for the footings closest to the shore. The Project Construction Managers decided that this settlement was due to consolidation settlement under increasing footing loads. This settlement was expected to stop when soil consolidation density reached its maximum, or in other words, as the foundation soil became fully compacted. The footings where settlement had occurred were jacked up, and solid steel packers inserted under the column base plates to hold the footings level. Construction Managers confirmed that the Module footings were now completely stable.
Following re-leveling of the settled footings, assembly of the Module second floor level was progressed. However, further significant settlement of the same base plate footings as before was identified. Construction was suspended. I then became involved, along with the Chinese Directors of the Fabrication Yard, in the inspection and assessment of causation of the high level of foundation settlement.
Some days later, an arbitration hearing was convened in the Yard’s Head Office Board Room. The Project construction team attended, along with the Project Client team (whom I represented). A small group of Chinese observers remained at the rear of the Board Room, and made no contribution to the discussion.
First arguments were presented by the Chinese construction representative. He presented his view that the foundation sub-soil was still not yet fully compacted, and would achieve a stable compaction level shortly, once construction resumed. He presented no factual evidence in support of his assessment, though he was personally in no doubt as to the accuracy of his statements. I perceived some pressure for me to support his statements.
I began my argument with a detailed description of the characteristics of the ‘poorly graded’ soil used in the Yard reclaim works, being mostly larger gravel and rocks, and then clayey fines. I then described the effects on the reclaim earth of the tidal changes in sea level. The effect of tidal water level changes in this type of soil is clearly defined in geotechnical literature. The fines component of the reclaim soil is saturated at high tide, clay fines dissolve, and are then eroded out as the tide recedes. This results in large voids in the sub-soil structure, which then cause the nearby footings to settle. The sub soil erosion mechanism due to tidal water movement would continue to cause foundation settlement indefinitely. At this point I noticed that the Chinese observers to the rear of the Board Room were leaving. They were already making their decision in this case.
The Chinese construction manager was dismissed from the Project immediately. Construction of the final deep water wharf along nearly 500m of the sea wall embankment where the Project was located was begun very rapidly. Within three months, the new deep water wharf was completed.
No further footing settlements were recorded.
Early condition of the sea wall embankment
Construction of new deep waterwharf to replace sea wall
Construction of new deep water wharf in progress
Module load-out across new deep water wharf