TNAG-1658-FCO40-2306-Daya-Bay-nuclear-power-station-project-safety-concerns-in-Ho-1987 — Page 61

NOV 10 '87 12:03 TIBCOOL) HK GOVT

1987-11-24 18:21

GNPJVC SHENZHEN

65709

P.17

APPENDIX 3

ALTERNATIVE TECHNICAL SOLUTIONS

<im is to determine, the

best

In overcoming the non-conformance the practical approach which is able to meet the original design criteria in all respects. The alternatives were as follows :

(1) To remove the first layer of concrete and start again.

(2)

ita

and It

As previously described, the first layer is heavily reinforced

removal would require use of explosives and heavy machinery. would also be necessary to remove the blinding concrete, waterproof membrane and screed which was placed on the rock foundation prior to constructing the first layer of the raft. However, the underlying rock foundation has been carefully

been carefully excavated and prepared to the correct profiles, and its structural capability could be damaged by auch action. It is also possible that surrounding areas of the work site could also be damaged.

If an attempt was made to remove the first layer and such damage did occur, the extent of remedial measures on the rock foundations would be significant. It is not justifiable to cause this extent of disruption and possible damage

possible damage if the raft can be completed to meet all criteria and standards of the original design using the existing first layer.

To accept the omission of the atarter bars and continue with the remaining layers without any further modification.

This solution has not been seriously considered. However, the inclined reinforcing bara above the starter bars in question fulfill two functions. One is to contribute to the strength of the

of the raft itaelf and, strictly speaking, the 260 starter

starter bars that were installad will meet the design criteria in this respect. The other function is to strengthen the gusset area higher up

area higher up where the building walls join the raft. In this respect, strictly speaking, the inclined bars will obtain sufficient anchoring for this purpose

1a the remaining four layers of the raft without the starter bars in the first layar.

A technical argument could have been pursued on the abovą basis and its result would be a structure which would meet the necessary design criteria. However, such an approach is not the best remedy that can be developed and, although it may meet the design criteria, it cannot be described as completely equivalent to the original. Consequently, it was rejected.

(3) To

Το leave the first layer in

in place but re-start the entire construction on top (ie, construct a new first layer on top of the existing concrete).