Slope engineering

Because of the topography and the rainfall, landslides are a big issue in Hong Kong.  When you go out by boat the hills of uninhabited islands are riven with landslide scars.  In areas where people are living, the government lands department manages these through a slope maintenance project.  Each area identified as a risk has a number, and is managed.  The good people in authority decided that the old slope behind our house needed fixing, and so fixing it is what they are doing - fixing it for the next thousand or so odd years.  It works like this: they have this boring machine that jacks and rotates segmented pipe into the hillside, rock, whatever it is, 8 metres worth.  They achieve this with a levered drill, which drives and rotates a cutting end, onto which they attach successive pieces of threaded pipe.  When it's done, the pipe gets filled with cement and is finished off with an expansion bolt attached to a rebar cage, set in a cut out recess of hill, itself which gets filled with cement.  And so you end up with the whole front of the hill, the bit which might shear off in a landslide, bolted into the rest of it  Before the recesses are filled, the naked slope is covered with mesh, and then the whole is filled in with piped, sprayed on cement.  It must cost an absolute king's ransom, and looks like taking 8 moths to achieve.  The crew is super-professional.  They start exactly on time, every day, and are a very skilled and polished unit; they consequently get through a very carefully sequenced and repeated mountain of work, still remembering to wave in a friendly way when they see you.  Quite amazing.

The drilled in pipe sections and boring machine

The re bar cages with expansion bolts in place, mesh being laid.

Spraying on concrete through the mesh and into the recesses.