| China-Russia Crude Oil Pipeline(CRCOP)engineering is the one of the four energy strategic channels in China,which were northeast,northwest,southwest and maritime channels,respectively.The CRCOP starts from Skovorodino of Russia,reaches China and ends at Linyuan station,across the Heilongjiang and Inner Mongolia provinces.The CRCOP engineering was implemented in two phases.The first stage project was in operation on January,2011.The second stage project has begun to be constructed in 2016 at Jagdaqi in Heilongjiang Province.The CRCOP has a great effect on improving the energy strategic channel in northeast,optimizing the supply and demand pattern of oil and revitalizing the economy.Moreover,it is an important measure to accelerate the energy strategic channel construction and ensure the state energy safety.CRCOP passes through Greater Khingan Range forest area,and the felling of trees changes the soil environment in the forest area.During the construction of the first stage of the CRCOP,several research,design and construction institutes have made many studies on the permafrost condition and ecological condition along the pipe line.However,there also exist several problems for the lake of experience of construction long distance oil pipe line in high latitude regions,which has a great risk for the operation of oil pipe line.In this paper,considering the engineering problems during the construction of the first stage of the CRCOP,the engineering geological condition was analyzed emphatically.Then,the permafrost degeneration along the line was forecasted.Base on the fruits above,the frost heave and thaw settlement under different inlet oil temperatures with different oil mass were simulated by ANSYS.Furthermore,the thermal disturbance between oil pipe line and accompanying road was analyzed later.The details of the work are as follows:(1)Analysis of the permafrost project environment in the China-Russian crude oil pipeline in Greater Khingan Range area.Survey for the natural geographical conditions and engineering geological conditions region and the planar distribution and development characteristics of permafrost regions along the China-Russian crude oil pipeline in the Greater Khingan Range area.On this basis,the engineering geological evaluation model of permafrost is established based on the grey relational grade.The along the pipeline engineering geology in accordance with the good,good,bad and poor four level is evaluated.(2)Analysis of permafrost degradation along the China-Russian crude oil pipeline,and ascertain the reasons for permafrost degradation.Permafrost forecast model is established based on climate change models,predict the future 100 years,the upper limit of permafrost degradation rate,and analyze the degradation process and degradation law of permafrost.(3)The development process and development law of soil freezing thawing under the condition of different annual output are studied in permafrost regions.By means of numerical simulation,study on the process of freezing and thawing,freeze-thaw circle and developing process of freezing and thawing depth with time under the condition of the annual throughput is respectively 3000*104 t/a and 1500*104 t/a,inlet oil temperature-6? to 10?,and analysis of long-term thermal stability of permafrost under the pipeline.By analyzing that after plumbing pipes around the soil freezing and thawing lag,in low temperature frozen surface thawing season start time late summer,winter surface began to freeze time earlier,the thawing layer back to frozen time earlier.(4)The thermal stability of permafrost in the pipeline under special structural measures was studied.The numerical simulation method is used to analyze the influence of pipeline insulation material on the size of frozen circle,thawing depth and freezing depth of permafrost thawing zone,and the variation law of thawing depth decrease with the increase of insulation layer thickness.In the early stage of pipeline operation,the thermal insulation material has obvious influence on the thawing depth.After long-term operation,the high temperature permafrost regions for crude oil pipeline heat preservation material thermal resistance effect of no in cold regions is obvious.(5)Study on the thermal disturbance of permafrost in the crude oil pipeline and the forest accompanying road.Based on the measured data,the characteristics of the temperature field of different sections of the roadbed are analyzed.By means of numerical simulation,the variation law of thermal stability of permafrost,and its mutual interference with the spatial distribution of pipeline and road engineering under the simultaneous action of crude oil pipeline and accompanying road are analyzed.The relationship between the heating process of subgrade foundation and the height of the subgrade is analyzed.Using temperature difference ?T as crude oil pipe and accompanying road influence the judgment standard,at different distances apart,the maximum temperature range and the law between the two are obtained when the distance is different.All this research shows that the construction of the China-Russia crude oil pipeline and accompanying road,changed the Greater Khingan Range area of permafrost engineering environment,research on the laws of the heat affected the safety of pipeline operation,freeze-thaw disasters prevention and second line engineering construction and forest ecological environment protection to provide technical support and reference. |
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