Discrete element numerical simulation of triaxial fluid solid coupling based on seepage experiment
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摘要: 卸压开采覆岩的应力场、裂隙场及渗流场耦合特性直接影响卸压瓦斯的运移特征。 本文 根据弹性煤样及贯穿裂隙煤样的应力渗流实验数据,结合渗流立方定律提出了数值模型中裂隙 煤岩体流固耦合参数的选取方法,建立了三轴加载流固耦合数值模型。 在此基础上模拟分析了 单轴及三轴加载过程中煤样应力、裂隙及渗流的耦合特性。 模拟结果表明:煤样渗透率随着轴向 应变的升高呈S形变化,在煤样内部裂隙产生前随着轴压的增加而逐渐减小;煤样内部裂隙的产 生及扩张使得渗透率开始升高,且裂隙扩张速度越快渗透率升高幅度越大;围压的升高使得煤样 内部裂隙产生及扩展速度减缓,致使渗透率降低阶段延长,煤样初始渗透率及屈服后的渗透率逐 渐减小。Abstract: Thecouplingcharacteristicsofcoalseamstress,fractureandseepagedirectlyaffectthemi⁃ grationcharacteristicsofpressurereliefgasduringtheprotectiveseammining*Inthispaper,combined withcubiclaw,themethodfortheselectionofthefluidsolidcouplingparametersofelasticjointsand persistentfracturewasproposedbasedontheexperimentaldataoftheelasticandpersistentfracture coalsamples*Meanwhile,thesimulationmodelingoffluidsolidcouplingfortriaxialflow testofcoal sampleswasbuilt*Onthebasisofthissimulationmethod,thecouplingcharacteristicsofthecoalsample stress,fractureandflowweresimulatedandanalyzedduringuniaxialandtriaxialloading*Thesimulation
resultsshow that the permeability of coal samples changes as S type with the increase of axial strain*Thepermeabilityofcoalsampledecreasesgraduallywiththeincreaseofaxialpressurebeforethe fractureofcoalsampledevelopment*Thepermeabilityofthecoalsamplesincreaseswiththedevelop⁃ mentofthefractures,andthefasterthefractureexpansionrateis,thehigherthepermeabilityincrea⁃ ses*Theincreaseofconfiningpressureresultedinthedecreaseofinternalfracturegenerationandprop⁃ agation,andthepermeabilityreductionstagewasextended*Theinitialpermeabilityandyieldingperme⁃ abilityofthecoalsamplesdecreasedgradually*
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