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Japan Earthquake/Tsunami Reconnaissance Team 3 -- Day 4

Tectonic Plate Shifting Cripples Wharf

The third of as many as seven ASCE reconnaissance teams is in Japan studying the impact on infrastructure caused by the 9.0 magnitude earthquake and tsunami on March 11. Following teams sponsored by the Structural Engineering Institute and the Geo-Institute, the third team is sponsored by the Coasts, Oceans, Ports, and Rivers Institute, and as such will be focused on damage to port structures. It is being led by Marc Percher, P.E., M.ASCE, a senior engineer with Halcrow Group in Oakland, Calif. He is a structural analyst and designer specializing in marine oil terminals and refinery structures. Percher and/or his teammates will be discussing their findings and experiences in regular posts.   

Read each day's entries:
Introduction  |  Day 1  |  Day 2  |  Day 3  |  Day 4  |  Day 5  |  Day 6

Day 4 -- Saturday, May 14

Warped pavement showing soli failure beneath

By Marc Percher

The team woke up early, feasted on a real Japanese breakfast at the hotel, and then departed for the Sendai container terminal complex. As each day begins, we have no idea of what we will see, or how the damage will affect us personally. However, so far, we’ve found that pile-supported wharves performed better than expercted. Today we also saw many locations where tectonic plate shifting resulted in in a height loss of about 0.6 meters, which means the berthing hardware no longer is the right height for vessels, and seawater can get onto the deck. Not exactly the most helpful effects for continued operations. 

A representative of the port of Sendai met us at the gate, and we followed them down to see four cranes in various states of success and failure. In some ways, the initial damage looked similar to that in Kobe following the 1995 earthquake. The first portion of the marginal wharf was “new” and was on fill rock that was placed after the sheetpile wall and deadman (steel wall at the water tied back to a big old concrete block with batter piles). The older section of the wharf was on natural sands and therefore performed much better. This difference in the performance based on the underlying soils extended into the backlands, where differential settlement followed the original shoreline, as shown in the photo below. Damage was caused not only by the soils, but was also affected by the batter piles at the newer portion, because the deadman had batter piles only in one direction of the wharf (transverse), yet the earthquake resulted in displacements in the other direction (longitudinal).

Crane still fine, engineer beamsThere were four large container cranes total at the site, two on the older, less damaged portion and two on the newer, more damaged portion. The cranes on the newer portion were something special as they are base-isolated, relying on an invention developed by Dr. Sugano from PARI, who is part of our team. A proud Dr. Sugano and an excited Yoshi Oritatsu can be seen at right. While the wharf structure was damaged, the cranes sailed through the event relatively unscaved. That said, this terminal will not be operational for a long time, and it will be a while before further investigations (first requiring digging out the existing structure) can find out the specifics of what happened.

Further down the road from the container port, there was a large public park which is no more. The park had a simple gravity structure on the harbor channel side, and this structure totally failed; however it’s unclear if the failure was caused by the earthquake or tsunami.  This gave us food for thought throughout lunch. After another tongue lunch, the group split up, to revisit some of the locations with fresh sets of eyes. By the end of the day we had been on the road for more than 12 hours, and we arrived at our hotel very tired, but ready for another day of seeing the unexpected.

Introduction  |  Day 1  |  Day 2  |  Day 3  |  Day 4  |  Day 5  |  Day 6

COPRI Solutions to Coastal Disasters – June 26-29

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June 26-29
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