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1.
采用改进岩石蠕变扰动试验装置对粉砂岩试件开展施加周期冲击扰动下单轴蠕变试验,研究周期冲击扰动下粉砂岩蠕变变形、蠕变速率及破坏特征.结果表明:冲击扰动会引起蠕变曲线产生新的波动,随冲击扰动次数增加,粉砂岩内部累积变形逐渐增加,进入稳定阶段时间明显缩短,进入加速蠕变阶段轴向应力阈值显著降低;在周期扰动作用下,粉砂岩蠕变占比与轴向应力呈指数关系,蠕变速率稳定值提高;冲击扰动加速粉砂岩内部裂隙发育,粉砂岩试件破坏形式更趋于脆性破坏.基于Mohr-coulomb准则,提出一种与时间有关的非线性黏滞体并引入损伤因子改进Burgers模型,建立粉砂岩蠕变扰动理论模型;该模型能很好描述周期冲击扰动下粉砂岩蠕变特性,可为深入研究冲击扰动下岩石蠕变失稳破坏提供参考.  相似文献   

2.
煤层顶板砂岩在高温下的力学特性及破坏机理   总被引:8,自引:0,他引:8  
采用偏光显微镜、扫描电镜及岩石力学试验系统等仪器设备研究了煤层顶板砂岩在常温到1200℃范围内的力学特性和破坏机理.结果表明,煤层项板砂岩在加热过程中强度急剧降低的温度与岩石内部裂隙形成和晶体形态变化的温度基本一致,说明岩石微观结构在高温下的变化对其力学特性有显著影响;煤层顶板砂岩中有机物在高温下的分解和析出,对砂岩中裂隙形成与发展具有一定的影响,该砂岩在高温作用下的破坏是晶体晶型转变和膨胀等产生的热应力及有机物析出共同作用的结果.  相似文献   

3.
为研究高温遇水冷却后不同岩性岩石在循环加卸载条件下的物理特性和力学响应特征的变化规律,对高温遇水冷却后的花岗岩、大理岩及绿砂岩试件分别开展了单轴压缩和循环加卸载试验. 结果表明,当加热温度超过400 °C后,三类岩石的体积增长率显著增加,400 °C可以作为三类岩石物理参数发生突变的阈值温度.总体上,三类热处理水冷却岩石的单轴抗压强度随温度的升高而降低,但花岗岩在200 °C温度处理后峰值强度比常温时有所增加. 在循环荷载作用下,花岗岩滞回曲线接近于线性,上限应力较高且不可逆变形小;而绿砂岩和大理岩的上限应力低于花岗岩且变形较大.相同温度热冲击下滞回环宽度大小顺序为绿砂岩>大理岩>花岗岩.随循环次数的增加,三类高温遇水冷却岩样的塑性变形减小,弹性模量增大,试件强度较单轴压缩均有提高;随温度升高,破坏面裂纹更为发育,破裂岩屑更为细碎.   相似文献   

4.
温度对岩石渗透率影响的实验研究   总被引:2,自引:0,他引:2  
对储层粉砂岩、灰岩、变质岩和砾岩渗透率受热变化规律进行了实验研究 ,并对岩石渗透率在高温作用下发生变化的机理进行了讨论。分析结果表明 ,岩石在常压条件下经过高温加热处理 ,其渗透率随温度的升高而呈增大趋势 ;岩石渗透率发生突变时存在一个阈值温度 ,组分不同的岩石 ,其阈值温度也不同。岩石渗透率的提高是由于岩心受热后产生了新的裂缝 ,裂缝延伸而形成了连通网络结构  相似文献   

5.
采用分离式霍普金森(SHPB)压杆装置对砂岩进行动态冲击压缩试验,通过不同的加载气压实现不同应变率条件下对煤矿区的砂岩进行冲击压缩,以此来分析煤矿区砂岩的动力学特性以及能量损耗规律。根据试验结果分析可得,应力-应变曲线反映出砂岩的动态弹性模量及峰值应力都表现出明显的应变率效应,动态压缩强度表现出很强的应变率效应,两者之间呈现线性关系;在动态冲击压缩中,动态抗压强度高于静态抗压强度,通过动态强度增长因子DIF可以反映岩石在动载条件下的强度指标;随着应变率的增大,砂岩试样单位体积吸收破碎耗能增加,试样破坏更严重,破坏程度与单位体积破碎耗能之间形成很好的对应关系。同时借助SEM扫描电镜分析冲击压缩后试样微观条件下的破坏模式,结合宏观上的破坏形态共同分析岩石的损伤特性。  相似文献   

6.
为了研究深部砂岩在热-水-力耦合作用下的动力学特性,利用自主研发的热-水-力耦合三轴岩土体动态冲击力学试验系统,分析了动态冲击下深部砂岩的力学参数并从能量的角度描述其破坏形态。研究结果表明:在具有主动围压、轴压、渗透水压及温度的耦合作用下,冲击气压增大时,深部砂岩的应力-应变曲线的峰值应力随之增大;深部砂岩的峰值应力与应变率变化表现出明显的正相关性,具体表现为随着应变率的增大,峰值应力不断增大;随着冲击气压的增大,破碎程度不断加大,深部砂岩的破坏形态向压剪破坏过渡和发展,岩石试件的破坏形态呈脆性向延性转变的趋势。试验结果可以为深部砂岩在实际爆破工程中提供参数支撑。  相似文献   

7.
温度对岩石渗透率影响的实验研究   总被引:17,自引:1,他引:16  
对储层粉砂岩、灰岩、变质岩和砾岩渗透率受热变化规律进行了实验研究。并对岩石渗透率在高温作用下发生变化的机理进行了讨论。分析结果表明,岩石在常压条件下经过高温加热处理,其渗透率随温度的升高而呈增大趋势;岩石渗透率发生突变时存在一个阈值温度,组分不同的岩石,其阈值温度也不同,岩石渗透率的提高是由于岩心受热后产生了新的裂缝,裂缝延伸而形成了连通网络结构。  相似文献   

8.
为研究高温花岗岩在热冲击作用下渗透性能变化规律,对不同温度花岗岩试件在空气中自然冷却、在水中(20℃,60℃,100℃)热冲击冷却等4种冷却条件下的渗透率变化规律进行分析,借助热冲击因子对不同冷却温度的热冲击破坏进行定量表征,研究结果表明:热冲击作用下试件渗透率增加幅度与岩石温度的升高呈指数关系;冷却介质与高温岩石之间的温差和对流换热系数共同影响热冲击过程中热量交换的速率,进而影响到热冲击破坏的结果;热冲击因子可以作为衡量热冲击破坏能力的物理量,热冲击破坏后花岗岩的渗透率随热冲击因子单调增加且存在阈值,超过阈值后试件渗透率随热冲击因子的增加而大幅度增加。  相似文献   

9.
为了探究不同种类岩石在点载荷作用下的能量转化规律,本文通过室内实验测定了细砂岩、花岗岩、黄砂岩、玄武岩、粉砂岩和红砖在点载荷作用下的位移-载荷曲线,得到6种岩石裂纹扩展过程和破裂形态.对细砂岩、黄砂岩、粉砂岩、红砖和花岗岩的峰前积聚能量、峰后释放能量、盈余能量和破坏经历时间、盈余能量释放速度进行了研究,给出了能量的演化规律,为工程稳定性预测提供理论基础.讨论了峰值载荷与能量转化之间的关系,给出了3个区间峰前积聚的能量、峰后释放的能量和盈余能量变化规律,并对危险性进行了评价.  相似文献   

10.
循环冲击载荷作用下砂岩破坏模式及其机理   总被引:3,自引:0,他引:3  
利用岩石动静组合加载SHPB试验装置对不同静载砂岩试件进行循环冲击试验,研究其破坏模式.在研究岩石试件界面摩擦力的基础上,对不同静载作用下岩石试件的应力状态进行分析.研究应力波斜入射到微裂纹时的作用效应,探索具有一定静载的岩石在循环冲击作用下的破裂机理.研究结果表明:对具有三轴静载的试件,应力波在其最大剪应力所在平面进行斜入射时优先破坏.在循环冲击载荷作用下,具有轴向静载的岩石在破坏过程中具有明显的端部效应,而没有轴向静载的岩石则没有端部效应;静载荷的组合形式对岩石在循环冲击作用时的破坏模式影响较大;无静载荷作用时,岩石在循环冲击时逐步破坏成几块,破裂面平行于纵向面,属于张应变破坏;只有轴向静载作用时,岩石试件第1次破坏形成共轭双曲线型破裂面,进而在入射界面处发生破坏,破坏都属于张剪破坏;具有三轴静载作用时,由于轴向静载的不同,岩石最终破坏成圆锥台、圆锥体和V型锥体,破坏属于拉剪破坏.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

14.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

15.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

16.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

17.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

18.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

19.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

20.
The non-orthogonal localized molecular orbital(NOLMO)is the most localized representation of electronic degrees of freedom.As such,NOLMOs are thus potentially the most efficient for linear scaling calculations of electronic structures for large systems.However,direct ab initio calculations with NOLMO have not been fully implemented and widely used,partly because of the slow convergence issue in the optimization of NOLMO.We devel-  相似文献   

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