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This paper proposes a underwater acoustic coherent chaotic communication scheme which is suitable for shallow water channel mainly at 80bps rate. The encoding uses a decoupling mode, and the modulated signal doesn't contain common binary information. Orthogonal basis signals are engendered directly by Gaussian white noise carriers. The tolerance of time synchronization and the ability of resistance to inter-symbol interference (ISI) are achieved. The binary mapping decoding is engendered in correlation demodulating mode, and the copy correlator is used to match processing. Some problems have been considered, such as the system detection threshold, Doppler matching, the frequency compensation of copy sample, etc. The theoretical calculation and test method are provided. We use 1 kHz narrowband signal to enhance the ability of anti-dispersive fading in shallow static and dynamic experiments. Robust communication is achieved while the receiving threshold is above 0dB, and meanwhile the transmission loss rule is verified in shallow water channel.

The Xixiayuan project is a regulating reservoir in china. The concrete dam section is constructed on soft rock foundation. In this paper, we present the case study on the treatment for the soft rock foundation. The treatment includes the construction of concrete cut-off wall, reinforcement by dynamic compaction method, and installation of the stone columns. The treatment was justified by the field instruments installed in the foundation. The measured data show that the treatment can reduce significantly the settlement at the foundation. Moreover, layered settlement was employed in the analysis. The results demonstrate that very small total and differential settlement occurred in the foundation. The analysis illustrate the success of the treatment for the soft rock dam foundation, and useful for gaining experience for future designs and analysis.