Control Measures on Surrounding Rock of Extra Large Soft Rock Chamber for Belt Unloading in Shajihai Coal Mine

Abstract

In order to solve problem on the surrounding rock control for extra-large chamber in Mesozoic soft rock in western mining area, taking the belt unloading chamber engineering in Shajihai coal mine as research object, the methods of field investigation, laboratory test, numerical calculation and field test were used, and control strategies and failure mechanism of chamber were studied. The results shows that the main reasons for deformation and failure of surrounding rock are extra-large section, insufficient self-bearing capacity, high expansive and loose pressure, defects with support design and construction. The mechanics mechanism of surrounding rock deformation is determined as composite type, i.e., I_AII_BCDIII_E type through mechanics theory of soft rock engineering. Based on the supporting philosophy of constant resistance with yielding, combination of softness and hardness, and cooperative control, the compound mechanics mechanism is reasonably transformed into some single types, then the control measures with "constant resistance with large deformation bolt (cable) & U shaped steel frame off wall & bottom anchor pipe with grouting & pouring concrete" are put forward. The engineering practice shows that the measures can effectively control the deformation of the super large soft rock chamber for belt unloading, which ensured stability of the project, and the application effect is good.