Xing Zhang Yifan Zhang Fan Yang

 A Large-scale Coal Mine locates at this area.  The problem of subsidence here is quite serious.  Use TRANSIENT ELECTRO- MAGNETIC METHOD to analysis local geology.

 The deep blue area shows low-resistivity zone which means aquifer.  The rise of the level of ground water in recent years is due to excavated old tunnel.  The collapsed post by this method has been confirmed by field drilling

 Coal hollow  Ground water penetration  Effective pressure losses  Gravity Earth Subsidence Formation

 Changes in elevation  Damage to structures such as roads, railroads, bridges and pipe network  Danger to life safety  Damage to private and public properties  Reduce the use value of the land

Earth subsidence in a construction site

Earth subsidence on a road

Earth subsidence on a bridge

 Use stone columns as foundation.  Some high-risk road decks were made of reinforced concrete to improve strength.  Impregnate grout to fill possible hole under foundation and prevent future subsidence.

 Cement mixing piles used to strengthen road sub-base.  Designed to support road for 24 hours after subsidence.  This allows remedial action(mostly grouting) to be taken.

 Piles used to strengthen sub-base.  Piles control settlement and prevent future subsidence.