In the course of a two-hour concert Mr. García's songs encompassed chunky hard rock, chamber-pop with string arrangements, jazz-tinged ballads, funk vamps and synthesizer lines.
First is the Swedish development of sound-wall blasting (to preserve rock strength), treated below under rock chambers, since its importance increases with size of the opening.
Since about 1960, rock bolts have had major success in providing the sole support for large tunnels and rock chambers with spans up to 100 feet.
Preservation of ground strength is beginning to win acceptance as vital for the safety of large rock chambers and also often a means of cost saving in tunnels.
The use of rock chambers for underground hydroplants seems certain to increase in most countries, particularly those in which until recently surface plants have been favoured because of their apparently lower cost.
For large rock chambers and also particularly large tunnels, the problems increase so rapidly with increasing opening size that adverse geology can make the project impractical or at least tremendously costly.
En route, sidetracks lead to a succession of rock chambers that secrete everything from ferns that originate from before the dinosaurs to a huge amphitheatre with 60m-high walls.
Rock tendons (prestressed cables or bundled rods, providing higher capacity than rock bolts) up to 250 feet long and prestressed to several hundred tons each have succeeded in stabilizing many sliding rock masses in rock chambers, dam abutments, and high rock slopes.
The carbon dioxide can then be cooled and pumped for storage in deep underground rock chambers, for example, replacing the fluid in saline aquifers.
