The valve at the bottom of auger can prevent drilling bits entering hollow pipe during operation. When drilling pipe is taken out and concrete grout is injected, the valve will be opened.

In order to improve crack resistance of concrete, test and analysis are made on the influence of mineral compositions of cement on brittleness of sand grout.

To control foundation seepage and exit gradient, a plastic concrete cut-off wall, a grout curtain, and a set of downstream pressure relief Wells are incorporated in the design.