The technology relates to prevention of an unforeseen postponed subsidence of the earth surface over abandoned mines. So far, the unforeseen subsidence is a serious problem. It causes dangerous events and deteriorates environment. For instance, chimney (or sinkhole) subsidence may destroy surface structures such as private building or another utility kind of oil or gas pipeline. In the last case spilling of the oil spoils the environment and gas explosion can create another serious damage. Even small ground depression may change slope of a creek bed and create a swamp, etc.The only popular measure to solve the problem is insurance. Great amount of money is paid to insurance companies by surface users annually. In addition, money is spent during arguments between the companies that exploit surface utilities (such as gas, transport companies) and mining companies. The main subject is: who should pay for reparation of damaged utilities.
The only technical measure to prevent unforeseen subsidence is to fill the underground cavities with sand, ash, etc. (Peng S. S. (1992). Surface Subsidence Engineering, SME, Littleton.). However, this measure is not practically widely adopted because of its high cost.

BRIEF DESCRIPTION
New proposed technology prevents unforeseen subsidence using drilling the holes over abandoned mines and artificial caving rock strata by blasting in special order and by special procedure. Suspending strata experiences maximum dilation during artificial caving. Therefore self-support effect occurs owing to maximum balking factor of the caved rock. To this end procedure of artificial caving should be accomplished at optimal mode: namely optimal distance between adjacent explosive charges, optimal amount of the explosive, etc. These special points depend upon local geological structure and properties of the strata. Hence the procedure mentioned above and its technological parameters are know how.

ADVANTAGES
New technology of ground control over abandoned mines has been successfully tested in a physical model. Physical modeling has shown that due to new technology employment bulking factor of rock strata has grown from 0.0623 to 0.1185 and surface subsidence has been diminished from 1.1 m to 0.2 m or 5.5 times. It saves money 1.4-2.1 times comparatively with the method of preventing unforeseen subsidence by filling the underground cavities.

AREA OF IMPLEMENYTATION
New technology may be used to control the strata caving over abandoned coal mines in Pennsylvania, Ohio, West Virginia, Connecticut in USA, in Donbass region in Ukraine, in Kuzbass region in Russia. The more expansion of underground coal mines is the more implementation. First shallow abandoned in the period 1900-1960 coal mines are the object of new technology implementation. To give the idea of scope it should be noted that over 1000 dangerous sites have been registered in Donetsk city only. These sites are abandoned shallow vertical shafts and mouths of slopes (Inclined shafts). Special commission supervises these sites because approximately every quarter, ground surface collapses somewhere that creates perilous situations.

HOW TO IMPLEMENT
Up to recently the research grant from CRDF has been got. This grant ($47,200) covers the first step of investigation. Namely during 2 years detail physical modeling should be accomplished to establish main points and the parameters of the technology. However final criterion of new technology efficiency is experiment in-situ. To conduct such an experiment in Ukraine it is needed approximately $213,000. Professor S.S. Peng from WVU (he is co-PI) agrees on the necessity of the experiment, however he said that in USA it will be rather expensive. The experiment should be conducted in both Ukraine and USA. Then potential customers may be found through the insurance companies. After this new technology should be advertised directly to these surface users. As the main evidence of efficiency of new technology will be the site (say in West Virginia), where experiment in-situ will have been conducting.

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