Rock Mass Quality Research For The Underground Petroleum Storage Cavern Of Yangpu Of Hainan Province

In this article,an underground oil seal structure will be built in the western city of Danzhou of Hainan province.At present,the international petroleum reserve is divided into the ground and underground oil depot,and underground oil depot occupy the main position for its Large scale.Underground oil depot is divided into two kinds,underground cavern and underground rock salt cavern.Comparing with the same capacity of the ground tank,underground cavern has the features of low cost,safe operation and less environmental pollution etc..Therefore,with the suitable engineering geological and other conditions,selecting underground cavern to storage oil should be the best choice.Underground oil seal structure characteristics:(1)In a natural state,underground oil depot requires only a little amount of support.So copare with ground oil depot,using it can save investment.However,It put forward higher requirements for the quality of the surrounding rock.That is,in the condition of site stability,surrounding rock,which is used to build underground oil depot,has a certain strength,so that the Mass excavationgoes smoothly.The rock structure is stable,and its stability can be kept for a few years.(2)As the water sealed cavern,it requires a proper amount of water underground to form a pressure,so that the oil is stored in the depot without leakage.As for the whole aspects,the quality of rock mass is good,but the rock mass has grown a certain amount of rock structural plan because of the tectonic influence,it not only affects the quality of rock mass and intensity,but also affects to the partial stress field distribution of the project area.So it has disadvantageous influence to underground hole's excavation and the adjacent formation stability.Therefore,we must conduct the rock mass quality graduation research to the main hole room of underground workshop,so that the project goes smoothly.The domestic and foreign experts put forward many kinds of classification(grading)methods for evaluating the rock quality research.Presently,which are used commonly at home and abroad are RQD classification method,Q system classification and BQ grading method.The paper combines with the actual situation and the experimental results of rock physical and mechanical data.We select the BQ formula for evaluating rock mass quality,and use the RMR system method to verify it,and then obtain the rock mass quality and the site and the depth where is suitable for the construction of the cavern.The methods which are used mainly to get the date of rock mass mechanics and permeability coefficient are drilling coring and laboratory measurement.In addition,because uderground petroleum storage caverns require certain groundwater quantity to keep the oil without leakage.Thus it is necessary to determine the assessment of groundwater inflow can meet the requirements or not,if it can't meet the demand,we must set up drencher system.Measurement of groundwater discharge methods are mainly water lifting test and pumping test and so on.Using the methods mentioned above to obtain cavern rock quality grade and groundwater inflow,Considering the two factors determine the buried depth of tunnel.The result shows that the three base address Yaxing,Guangdi and Longshan,Yaxing was eliminated during the preliminary selection,after comparison and choice again,Longshan was eliminated.Rock of Guangdi repository site,which are from the more complete to complete,are mainly feldspar gneiss,granite porphyry,diorite and diorite porphyrite which are hard,high strength.Guangdi's engineering geological characteristics is fine,the rock below the surface 33.10 metres is ?,?,So we choose Guangdi finally.