采用PHF-LSM(permeability-based hydraulic fracture-level set method)水力压裂计算模型,建立了含节理分布的岩石材料模型,将其计算结果与裂缝几何特征和诱发应力理论解对比验证模型正确性,在此基础上分析节理对水力裂缝应力阴影效应...采用PHF-LSM(permeability-based hydraulic fracture-level set method)水力压裂计算模型,建立了含节理分布的岩石材料模型,将其计算结果与裂缝几何特征和诱发应力理论解对比验证模型正确性,在此基础上分析节理对水力裂缝应力阴影效应的影响.计算结果表明:基于弥散裂缝模型的PHF模型应使用等效开裂区域最外侧结点位移差作为裂缝等效开度;节理的存在会影响裂缝注水过程中水压力变化,同时会引起裂缝等效开度的增大;较大的节理入射角度与距注水点较小的节理高度会产生更大诱发应力,同时会引起最小主应力方向的改变,导致更强应力阴影效应,裂缝偏转加强.展开更多
基于渗透率修正和水平集法的水力压裂数值计算模型(permeability-based hydraulic fracture-level set method,PHF-LSM)是以Biot固结理论为基础建立一种弥散裂缝模型.模型是通过弱化开裂及损伤区域岩石材料性质来模拟裂缝的发展过程,因...基于渗透率修正和水平集法的水力压裂数值计算模型(permeability-based hydraulic fracture-level set method,PHF-LSM)是以Biot固结理论为基础建立一种弥散裂缝模型.模型是通过弱化开裂及损伤区域岩石材料性质来模拟裂缝的发展过程,因此求解过程中无法给出水力裂缝的几何特征.依据水力裂缝传播过程中的平均有效应力场分布建立PHF-LSM方法的水力裂缝的等效路径和等效高度;依据等效传播路径周围位移场计算水力裂缝的等效开度,并通过与KGD理论模型对比进行验证所提方法的有效性.计算了均质和非均质岩石材料中裂缝等效几何特征的动态发展特性.结果表明,所提出的等效计算方法弥补了PHF-LSM无法得到水力裂缝几何特征的不足.展开更多
基于PHF(permeability-based hydraulic fracture)模型,采用水平集方法(level set method,LSM)描述材料边界分布,并用多尺度方法MT模型,对材料有效参数进行均匀化,建立适用于考虑非均质岩石材料细观界面特征分布与水力裂缝动态发展过程...基于PHF(permeability-based hydraulic fracture)模型,采用水平集方法(level set method,LSM)描述材料边界分布,并用多尺度方法MT模型,对材料有效参数进行均匀化,建立适用于考虑非均质岩石材料细观界面特征分布与水力裂缝动态发展过程的PHF-LSM-MT数值计算模型.该模型解决了已有PHF-LSM模型无法精确描述积分点作用范围内细观尺度材料分布特征的问题.通过比较包裹体几何分布和体积分数影响下的有效弹性参数,验证了采用MT模型均匀化细观特征的可行性;在此基础上,对非均质岩石水力裂缝发展过程进行研究,得到了考虑细观界面特征情况下的裂缝发展过程,探讨了等效开裂区域影响范围内关键位置的水压力变化特征和应力路径发展过程.展开更多
采用PHF-LSM(permeability-based hydraulic fracture-level set method)水力压裂数值计算模型,模拟并分析了均质与分层岩石材料中分段压裂过程引起的应力阴影效应.通过与单一裂缝诱发应力理论解的对比,验证了PHF-LSM考虑应力阴影效应...采用PHF-LSM(permeability-based hydraulic fracture-level set method)水力压裂数值计算模型,模拟并分析了均质与分层岩石材料中分段压裂过程引起的应力阴影效应.通过与单一裂缝诱发应力理论解的对比,验证了PHF-LSM考虑应力阴影效应的可行性.以此模型为基础分析了单一裂缝发展过程中,岩石材料参数与初始应力条件对诱发应力场的影响,以及均质与分层岩石材料的多裂缝起裂过程中不同压裂间距与压裂顺序产生的应力阴影效应.数值计算结果表明:泊松比、抗拉强度与孔隙率的增加会增大裂缝引起的诱发应力与净压力比值的峰值,而弹性模量和水平主应力差的增大会减小该峰值;裂缝间距的扩大可以减弱裂缝间应力阴影效应;两步压裂与顺序压裂的裂缝总面积均大于同时压裂时的面积,但顺序压裂与两步压裂会带来更高的起裂压力;产层厚度与压裂间距的减小会增大应力阴影效应.展开更多
[Objectives] To explore the inhibitory effects of flavonoids from Scutellaria baicalensis Georgi stems and leaves against abnormal formation of PHF and regulation mechanism of protein phosphatase(PP) in okadaic acid(O...[Objectives] To explore the inhibitory effects of flavonoids from Scutellaria baicalensis Georgi stems and leaves against abnormal formation of PHF and regulation mechanism of protein phosphatase(PP) in okadaic acid(OA) induced brain injury in rats.[Methods]Male Sprague-Dawley rats were treated with OA(200 ng/kg) in the lateral ventricle to establish a memory impairment model,and Morris water maze was used to screen the memory impairment model.Rats were intragastrically administered with 25,50 and 100 mg/kg SSF daily for 36 d.The protein expressions of PHF,PP1,PP2A-Cα,PP2A-Cβ,PP2 CA and PP2 CB in rat cortex and hippocampus were determined by Western blot.Ginkgo biloba leaf flavonoids were used as positive control drugs.[Results]Compared with the sham-operated rats,the expression of PHF protein in the cortex and hippocampus of the model group was significantly increased(P < 0.01);protein expression of PP2A-Cα and PP2A-Cβin the cortex and hippocampus,and PP2 CB in the hippocampus were significantly decreased(P < 0.05);protein expression of PP2 CA and PP2 CB in the cortex was significantly increased(P < 0.01);protein expression of PP1 in the cortex was significantly decreased(P < 0.01).Compared with the model rats,25,50 and 100 mg/kg SSF 36 d reversed the protein expression of PHF,PP2A-Cα and PP2ACβ in rat cortex and hippocampus and expression of PP1 in rat cortex induced by OA,but had no significant effect on the protein expression of PP2 CA and PP2 CB,G.biloba flavonoids also showed similar results to SSF.[Conclusions] SSF can significantly inhibit the abnormal formation of PHF in rat brain induced by OA.The inhibitory effect may be related to the regulation of PP1,PP2A-Cα and PP2A-Cβ protein expression in cerebral cortex and hippocampus by SSF,but less related to the regulation of PP2 CA and PP2 CB.展开更多
文摘采用PHF-LSM(permeability-based hydraulic fracture-level set method)水力压裂计算模型,建立了含节理分布的岩石材料模型,将其计算结果与裂缝几何特征和诱发应力理论解对比验证模型正确性,在此基础上分析节理对水力裂缝应力阴影效应的影响.计算结果表明:基于弥散裂缝模型的PHF模型应使用等效开裂区域最外侧结点位移差作为裂缝等效开度;节理的存在会影响裂缝注水过程中水压力变化,同时会引起裂缝等效开度的增大;较大的节理入射角度与距注水点较小的节理高度会产生更大诱发应力,同时会引起最小主应力方向的改变,导致更强应力阴影效应,裂缝偏转加强.
文摘基于渗透率修正和水平集法的水力压裂数值计算模型(permeability-based hydraulic fracture-level set method,PHF-LSM)是以Biot固结理论为基础建立一种弥散裂缝模型.模型是通过弱化开裂及损伤区域岩石材料性质来模拟裂缝的发展过程,因此求解过程中无法给出水力裂缝的几何特征.依据水力裂缝传播过程中的平均有效应力场分布建立PHF-LSM方法的水力裂缝的等效路径和等效高度;依据等效传播路径周围位移场计算水力裂缝的等效开度,并通过与KGD理论模型对比进行验证所提方法的有效性.计算了均质和非均质岩石材料中裂缝等效几何特征的动态发展特性.结果表明,所提出的等效计算方法弥补了PHF-LSM无法得到水力裂缝几何特征的不足.
文摘基于PHF(permeability-based hydraulic fracture)模型,采用水平集方法(level set method,LSM)描述材料边界分布,并用多尺度方法MT模型,对材料有效参数进行均匀化,建立适用于考虑非均质岩石材料细观界面特征分布与水力裂缝动态发展过程的PHF-LSM-MT数值计算模型.该模型解决了已有PHF-LSM模型无法精确描述积分点作用范围内细观尺度材料分布特征的问题.通过比较包裹体几何分布和体积分数影响下的有效弹性参数,验证了采用MT模型均匀化细观特征的可行性;在此基础上,对非均质岩石水力裂缝发展过程进行研究,得到了考虑细观界面特征情况下的裂缝发展过程,探讨了等效开裂区域影响范围内关键位置的水压力变化特征和应力路径发展过程.
文摘采用PHF-LSM(permeability-based hydraulic fracture-level set method)水力压裂数值计算模型,模拟并分析了均质与分层岩石材料中分段压裂过程引起的应力阴影效应.通过与单一裂缝诱发应力理论解的对比,验证了PHF-LSM考虑应力阴影效应的可行性.以此模型为基础分析了单一裂缝发展过程中,岩石材料参数与初始应力条件对诱发应力场的影响,以及均质与分层岩石材料的多裂缝起裂过程中不同压裂间距与压裂顺序产生的应力阴影效应.数值计算结果表明:泊松比、抗拉强度与孔隙率的增加会增大裂缝引起的诱发应力与净压力比值的峰值,而弹性模量和水平主应力差的增大会减小该峰值;裂缝间距的扩大可以减弱裂缝间应力阴影效应;两步压裂与顺序压裂的裂缝总面积均大于同时压裂时的面积,但顺序压裂与两步压裂会带来更高的起裂压力;产层厚度与压裂间距的减小会增大应力阴影效应.
基金Acknowledgments We thank the cell biology core facility for confocal study. The PHF8 antibody was kindly provided by Dr Jiemin Wong （East China Normal University）. This work was supported by the National Basic Research Program of China （2007CB947900, 2010CB529705, 2007CB947100）, the Chinese Academy of Sci- ences （KSCX2-YW-R-04, KSCX2-YW-R-I 11）, the National Natural Science Foundation of China （30870538, 90919026）, Postdoctoral fellowship （20090460670）, and the Council of Shanghai Municipal Government for Science and Technology.
基金Supported by Hebei Province Colleges Hundred Outstanding Innovative Talent Support Program(First Session)Key Science and Technology Project of Hebei Provincial Education Department(ZD20131022)+1 种基金Project for Key Disciplines of Traditional Chinese Medicine in Colleges and Universities of Hebei Province(Ji Jiao Gao[2013]No.4)Program of Key Development Discipline of Pharmacology of Traditional Chinese Medicine in Chengde Medical College(Cheng Yi Fa[2016]No.140)
文摘[Objectives] To explore the inhibitory effects of flavonoids from Scutellaria baicalensis Georgi stems and leaves against abnormal formation of PHF and regulation mechanism of protein phosphatase(PP) in okadaic acid(OA) induced brain injury in rats.[Methods]Male Sprague-Dawley rats were treated with OA(200 ng/kg) in the lateral ventricle to establish a memory impairment model,and Morris water maze was used to screen the memory impairment model.Rats were intragastrically administered with 25,50 and 100 mg/kg SSF daily for 36 d.The protein expressions of PHF,PP1,PP2A-Cα,PP2A-Cβ,PP2 CA and PP2 CB in rat cortex and hippocampus were determined by Western blot.Ginkgo biloba leaf flavonoids were used as positive control drugs.[Results]Compared with the sham-operated rats,the expression of PHF protein in the cortex and hippocampus of the model group was significantly increased(P < 0.01);protein expression of PP2A-Cα and PP2A-Cβin the cortex and hippocampus,and PP2 CB in the hippocampus were significantly decreased(P < 0.05);protein expression of PP2 CA and PP2 CB in the cortex was significantly increased(P < 0.01);protein expression of PP1 in the cortex was significantly decreased(P < 0.01).Compared with the model rats,25,50 and 100 mg/kg SSF 36 d reversed the protein expression of PHF,PP2A-Cα and PP2ACβ in rat cortex and hippocampus and expression of PP1 in rat cortex induced by OA,but had no significant effect on the protein expression of PP2 CA and PP2 CB,G.biloba flavonoids also showed similar results to SSF.[Conclusions] SSF can significantly inhibit the abnormal formation of PHF in rat brain induced by OA.The inhibitory effect may be related to the regulation of PP1,PP2A-Cα and PP2A-Cβ protein expression in cerebral cortex and hippocampus by SSF,but less related to the regulation of PP2 CA and PP2 CB.
