Some hydropower stations were built on soluble rocks such as carbonate and the flow field,chemical field and solid properties around a dam site were changed,which may have adverse effect on the operation.Two factors,surface reaction and mass transfer,were thought to control the dissolution process.Based on this,a model of coupled fluid flow and chemical dissolution in a single fracture was built up and solved.And the results showed that the dissolution front is not a plane,but somehow like wormholes.And the aperture along the fracture becomes narrower.Although the flow through the fracture becomes larger,the amplitude was small.And the range and growth rate of equivalent hydraulic aperture are much smaller than actual average aperture.The distribution of Ca2+concentration is similar to the aperture,while the reaction rate at upstream is much faster than the one at downstream.And along the whole fracture it is controlled by surface reaction initially. As the dissolution processing,it turns to mass transfer control near the inlet,while it remains surface reaction controlled near the downstream.
