振动与冲击
振動與遲擊
진동여충격
JOURNAL OF VIBRATION AND SHOCK
2014年
23期
127-132,154
,共7页
王观石%胡世丽%李志文%王星光
王觀石%鬍世麗%李誌文%王星光
왕관석%호세려%리지문%왕성광
完整岩体%滤波特性%Maxwell模型%应力波%衰减系数
完整巖體%濾波特性%Maxwell模型%應力波%衰減繫數
완정암체%려파특성%Maxwell모형%응력파%쇠감계수
intact rock mass%filter property%Maxwell model%stress wave%attenuation coefficient
不同频率范围内的应力波在岩体的传播过程中,衰减系数对频率的依赖性具有显著差异。通过现场试验研究完整岩体对测井频率范围内应力波的滤波特性,针对常用黏弹性模型在描述衰减系数与频率关系存在不足,在频域上对黏性系数进行非定常处理,建立黏性系数非定常Maxwell模型,采用波形相关系数评价改进模型的滤波效果。研究结果表明,完整岩体总体上表现为低通滤波,在低通滤波范围内具有非等间距带通滤波特性,随传播距离增加,带通数逐渐减小;在吸收频率过渡带,应力波衰减系数随频率变化非常快,黏性系数非定常Maxwell模型能够有效描述应力波在完整岩体中的衰减系数变化规律;吸收频率过渡带的边界频率与传播距离成负指数关系,吸收频率过渡带的陡度参数可以近似认为是常数;随传播距离增加,黏性系数非定常Maxwell模型描述完整岩体的滤波效果明显提高,当传播距离为4.75 m时,波形相关系数达到0.89,表明采用改进模型描述完整岩体是有效的。
不同頻率範圍內的應力波在巖體的傳播過程中,衰減繫數對頻率的依賴性具有顯著差異。通過現場試驗研究完整巖體對測井頻率範圍內應力波的濾波特性,針對常用黏彈性模型在描述衰減繫數與頻率關繫存在不足,在頻域上對黏性繫數進行非定常處理,建立黏性繫數非定常Maxwell模型,採用波形相關繫數評價改進模型的濾波效果。研究結果錶明,完整巖體總體上錶現為低通濾波,在低通濾波範圍內具有非等間距帶通濾波特性,隨傳播距離增加,帶通數逐漸減小;在吸收頻率過渡帶,應力波衰減繫數隨頻率變化非常快,黏性繫數非定常Maxwell模型能夠有效描述應力波在完整巖體中的衰減繫數變化規律;吸收頻率過渡帶的邊界頻率與傳播距離成負指數關繫,吸收頻率過渡帶的陡度參數可以近似認為是常數;隨傳播距離增加,黏性繫數非定常Maxwell模型描述完整巖體的濾波效果明顯提高,噹傳播距離為4.75 m時,波形相關繫數達到0.89,錶明採用改進模型描述完整巖體是有效的。
불동빈솔범위내적응력파재암체적전파과정중,쇠감계수대빈솔적의뢰성구유현저차이。통과현장시험연구완정암체대측정빈솔범위내응력파적려파특성,침대상용점탄성모형재묘술쇠감계수여빈솔관계존재불족,재빈역상대점성계수진행비정상처리,건립점성계수비정상Maxwell모형,채용파형상관계수평개개진모형적려파효과。연구결과표명,완정암체총체상표현위저통려파,재저통려파범위내구유비등간거대통려파특성,수전파거리증가,대통수축점감소;재흡수빈솔과도대,응력파쇠감계수수빈솔변화비상쾌,점성계수비정상Maxwell모형능구유효묘술응력파재완정암체중적쇠감계수변화규률;흡수빈솔과도대적변계빈솔여전파거리성부지수관계,흡수빈솔과도대적두도삼수가이근사인위시상수;수전파거리증가,점성계수비정상Maxwell모형묘술완정암체적려파효과명현제고,당전파거리위4.75 m시,파형상관계수체도0.89,표명채용개진모형묘술완정암체시유효적。
The effects of stress wave in different frequency ranges on attenuation coefficient are different.The filtering properties of stress wave propagating in intact rock mass within scope of log frequency were studied through field test.Based on the shortcoming of common viscoelastic model predicting the relationship between attenuation coefficient and frequency,Maxwell model for unsteady viscosity coefficient was established after the unsteady treatment of viscosity coefficient.The filtering effect of the improved model was evaluated using the waveform correlation coefficient.The study results indicated that intact rock mass has a low-pass filtering property and unequal interval band-pass property within scope of a low-pass filter, the number of band-pass decreases with increase in propagation distance;attenuation coefficients of stress wave with frequency change greatly in the transition zone of absorption frequency,the change rule of attenuation coefficient of stress wave propagation in intact rock mass is effectively described with the improved Maxwell model for unsteady viscosity coefficient;the boundary frequency of the transition zone of absorption frequency has a negative exponential relationship with propagation distance,the edge gradient parameter of the transition zone of absorption frequency is approximately constant.The filtering effect of intact rock mass improves obviously using the improved Maxwell model with increase in propagation distance;the waveform correlation coefficient reaches 0.89 when propagation distance of stress wave is 4.75 m;the improved model is capable of describing the filtering properties of intact rock mass.