Through interrelated impacting and grabbing test of mechanical properties for various rock samples, this paper calculates the consumed energy of percussion clamshell during construction.

Optimization of the control on the falling reference of the grab bucket of ore ship unloader;

According to the actual working conditions of bolting-shotcrete supporting in coal-mine tunnel,the working mechanism of different buckets was studied,their merits and demerits were analysed,and the double-crank grab bucket with assistant linkage was proved to be an ideal choice of grabbing materials in coal-mine tunnel because its motion trace was definite and symmetric and occupied lesser space.

This paper analyses in quantity for the key factors to influence the fold and unfold of the grab bucket in the four-drum grab bridge ship unloader.

Several problems in designing long stay bar double jaw boards grab;

Numerical analysis of the disabled grab and some improvements in structure;

Simulation and analysis of grab lifting dynamic load coefficient;

The clamshell excavates the deep and shallow wall troughs because it has the characteristics of high working efficient, easy to move and .

In the construction of foundation seepage control wall for construction cofferdam of Wangpuzhou Water Control Project in the Hanjiang River,the clamshell was used to dig the trench.

When a clamshell dredger is used to carry out over-depth and over-width dredging,accuracy control is always one of the difficulties.