Construction of Buildings and Structures on Rock Concrete Compensation Slabs when Building in Subsided Areas of Abandoned Coal Mines and Open Pits

Abstract

For building in subsided areas of abandoned coal mines and open pits on soils damaged by anthropogenic impact and mining operations, it is proposed to base buildings and structures on a three-layer slab founda- tion including: a solid reinforced concrete foundation slab, a sub-ballast of ground overburden burnt rocks and a rock concrete compensation slab lo- cated between them. During subsidence of damaged soils, the rock concrete compensation slab, collapsing and increasing in volume, fills the sinkhole lens under the building with pieces of rock concrete, protecting the rein- forced concrete foundation slab from destruction. It was experimentally es- tablished that for the production of rock concrete compensation slabs, ce- ment rock concrete with aggregate of ground burnt rocks with a coarse frac- tion (–20+10) mm and a fine fraction (−0.63) mm should be used; the ratio of the percentage mass fraction of coarse and fine fractions being 25/75 and 50/50 and the cement-water mass ratio C:W being 1:0.5. The reinforced concrete compensation slabs of the recommended composition can take a design load of up to 9-11 MPa in dry and up to 8-9 MPa in water-saturated conditions. The use of ground overburden burnt rocks for the manufacture of rock concrete compensation slabs and sub-ballast will allow utilizing overburden burnt dumps and improving the environmental situation when building in subsided areas of abandoned mining enterprises.

Sand-Cement Cushions for Preparation of the Bases of Mining Buildings and Structures

“…Для изготовления образцов принимали три стандартные фракции песка: «−0,315», «−0,63 +0,315» и «−1,25 +0,63» мм. Песок с более крупными стандартными фракциями при исследовании не применяли, поскольку известно, что с увеличением размеров песчаных фракций в песке прочность песчано-цементного камня снижается [13].…”

“…В этой связи при экспериментальных исследованиях искусственный песок изготавливали в лабораторной шаровой мельнице из песчаника на глиноизвестковом цементе с пределом прочности на одноосное сжатие Rc=38 МПа. Перемолотую породу рассеивали на фракции:«−1,25 +0,63», «−0,63 +0,315» и «−0,315» мм на лабораторных ситах [13,14].…”