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高温下石灰岩和砂岩膨胀特性的试验研究 总被引：2，自引：0，他引：2
利用自行研制的高温岩石膨胀特性试验装置,对石灰岩和砂岩试件300～700 ℃高温过程中的膨胀特性进行试验研究。试验结果表明,升温过程中,石灰岩和砂岩的膨胀应力随温度的增加而增大,且砂岩膨胀速率比石灰岩大,刚到700 ℃时砂岩膨胀应力是石灰岩的2.45倍。升温过程中膨胀应力与温度曲线的拟合函数为2次抛物线,相关系数达0.94以上。恒温过程中,随时间延长2种岩石的膨胀应力缓慢增加,最后逐渐趋于稳定的数值。600 ℃高温后2种岩石膨胀均达到极限,但具体表现不同,700 ℃恒温结束时砂岩稳态膨胀应力是石灰岩的3.14倍。岩石热膨胀应力变化与其岩性、内部矿物分解、孔隙率变化、声速变化等有显著关系。 相似文献
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《岩土力学》2021,(4)
为研究石灰岩物理和动力学性质受高温作用影响的规律,对常温和经历100～800℃高温作用后石灰岩试件进行物理参数测试,利用SHPB试验装置开展相同加载条件冲击压缩试验。研究结果表明:石灰岩主要矿物成分为方解石和白云石,常温石灰岩结构致密,随作用温度升高,白云石逐渐分解形成微米级颗粒,试件颜色由灰白色逐渐变浅至白色,体积增大,质量、密度和纵波波速减小,且变化速率与作用温度密切相关。不同高温作用后动压缩应力–应变曲线变化规律基本一致;动抗压强度和动弹性模量随作用温度升高表现为先小幅增加后大幅降低,与作用温度呈负相关二次函数关系,200℃时最大;动应变和应变率与作用温度呈正相关二次函数关系;破坏形态表现为由脆性向延脆性破坏转化,200℃时破坏程度最小,随作用温度升高破坏程度加剧、碎块粒径逐渐变小,800℃时碎块基本呈现为粉末状。 相似文献
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《地质灾害与环境保护》2021,32(1)
对类岩石试件进行高温作用后的单轴动态压缩试验和劈裂拉伸试验。结果表明:(1)水泥砂浆试件经历各种温度高温作用后,随着应变率的增加,试件的抗压强度和压缩弹性模量基本呈逐渐增加的趋势,峰值应变呈无明显的固定变化规律。(2)水泥砂浆试件经高温作用后,试件的抗压强度越低,对应变率的敏感性也越强。(3)水泥砂浆试件经高温作用后,随着位移加载速率的增加,试件的劈裂拉伸强度基本呈逐渐增加的趋势。 相似文献
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石灰岩和砂岩高温力学特性的试验研究 总被引：3，自引：1，他引：2
利用自行研制的岩石加温装置和RMT-150C岩石力学试验机, 对石灰岩和砂岩试样高温后的力学特性进行了试验研究。试验结果表明, 随着温度升高, 两种岩石纵波波速逐渐减小。单轴压缩过程中的全程应力应变曲线经历了压密、弹性、屈服、破坏4个阶段; 达到峰值应力后两种岩石均发生脆性破坏, 砂岩破坏时呈锥形炸裂, 而石灰岩则呈草捆状破坏。高温对两种岩石的强度都有一定的弱化作用, 其峰值应力都随温度升高而降低, 石灰岩700 ℃时强度降幅达84.59 %, 而砂岩强度仅比常温降低22 %左右。两种岩石的峰值应变都随温度升高逐渐增大, 但具体表现不尽相同, 石灰岩500 ℃时应变增加了30.57 %, 500 ℃之后峰值应变基本无变化, 甚至到700 ℃时还略有降低; 砂岩700 ℃时峰值应变增加了80.63 %, 其峰值应变的变化与其微观结构变化相关。随着温度升高, 两种岩石的弹性模量和变形模量均减小, 700 ℃时石灰岩弹性模量降幅为86.8 %, 砂岩弹性模量降幅为46.94 %; 700 ℃时石灰岩变形模量下降了83.9 %, 砂岩的变形模量下降了53.06 %。 相似文献
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任海波 《地质灾害与环境保护》2019,30(4)
为了研究高温和冻融共同作用下对岩石力学特性的影响,对类岩石试件进行高温和冻融作用,然后对试件进行单轴压缩试验,研究高温和冻融作用的先后顺序对试件的抗压强度、峰值应变的影响。结果表明:(1)试件经历各种温度高温作用后,再进行冻融循环作用,随着循环次数的逐渐增加,试件的抗压强度也逐渐降低,试件的峰值应变基本呈逐渐增加的趋势。(2)试件经历冻融循环后、再经高温作用,强度均随着高温温度的增加而逐渐降低,峰值应变随着高温温度的增加基本呈逐渐增加的趋势。(3)先经冻融循环25次、再经高温作用的强度,比先经高温作用、再经冻融循环25次作用的强度高。 相似文献
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中高温三轴应力下鲁灰花岗岩热破裂声发射特征的试验研究 总被引：5，自引：1，他引：4
在中高温三轴应力作用下岩石内部物理化学性质和结构特性将发生变化,随着岩石内部结构的变化会引发一系列的声发射现象。通过试验研究了大试件花岗岩在三轴压力状态下声发射随温度的变化规律。试验研究表明：①随着温度升高,岩石的声发射现象是间断发生的;②花岗岩存在一个开始发生热破裂的门槛值温度,其值为120 ℃左右;③试验温度范围内花岗岩热破裂的声发射现象可分为5个阶段,即岩石原生裂隙整合阶段、热破裂前声发射静默阶段、热破裂声发射阶段、大规模热破裂后声发射静默阶段、二次热破裂开始阶段。 相似文献
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砂岩高温前后超声特性的试验研究 总被引：5，自引：0，他引：5
对焦作砂岩经历不同温度（100 ℃～1 200 ℃）前后超声纵、横波波速和几何尺寸进行了量测,进行了单轴抗压强度试验,计算了超声波纵波经过岩样的衰减系数,应用波速与弹性模量的关系计算了岩样的裂隙密度。比较了经历不同温度前后的岩样体积、超声波速、衰减系数的变化。结果表明,岩样在经历高温后内部微裂隙发展,使结构致密性下降,超声波速降低;对经历不同温度后的岩样波速改变与强度变化规律有明显差异,但超声衰减系数与强度变化规律相似,可以为强度评价提供一定参考。 相似文献
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利用自主研发的含瓦斯煤热-流-固耦合三轴伺服渗流装置,对不同温度条件下型煤试件在气体压力升降过程的渗流特性进行了试验研究,以模拟随采深增加引起的地温升高条件下煤的渗透特性。同时,为探讨低渗储层的滑脱效应进行了相同条件下氦气的平行试验。研究结果表明：（1）升压阶段,轴向应变增大,径向应变减小,近似呈线性变化;降压阶段,随气体压力降低,应变呈现出与升压阶段相同的变化趋势。随温度升高,应变随气体压力变化的斜率增大。（2）升压阶段,随气体压力升高,渗透率呈二次抛物线型变化,约在气体压力为3.0 MPa左右到达最小;降压阶段,随气体压力减小,渗透率先略有减小后增大,升压阶段渗透率大于降压阶段渗透率。（3）升压阶段滑脱效应引起的渗透率变化量大于降压阶段的变化量,且滑脱效应所引起的渗透率变化量随气体压力增加呈幂指数函数降低。 相似文献
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We have studied the evolution of the texture in two granites and two limestones subjected to slow and uniform temperature change. Each granite has a different grain size and each limestone a different texture: Carrare crystalline limestone and Crepey oolitic limestone. Temperature was varied from 200°C to 700°C. Scanning Electron Microscope observations of different rock samples show that during thermal cycling intercrystalline boundaries in granites widen out progressively and porosity increases. New microcracks appear in crystals between 500°C and 600°C. In Carrare crystalline limestone, intercrystalline cracks appear at temperatures as low as 200°C. Due to its heterogeneous cracks appear at temperatures as low as 200°C. Due to its heterogeneous increasing temperature. Longitudinal wave velocity and intrinsic permeability show good correlation with the Scanning Electron Microscope observations. 相似文献
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Measurements are presented of volume changes in granite during room-temperature compression to 100, 200 and 300 MPa confining pressure followed by temperature increase to 900°C. Comparison with thermal expansion and compressibility data for the constituent minerals allows changes in porosity to be estimated. Under confining pressure, porosity is found to decrease with heating to 200°C through expansion of the minerals into cracks which are thought to be related to the geological cooling history of the rock. Between 200°C and 840°C porosity increases as a result of differential thermal expansion of the constituent minerals, but crack opening is increasingly suppressed at higher confining pressures. Extrapolation of the results indicates that differential thermal expansion can no longer cause crack opening in dry granite at confining pressures in excess of 450 MPa. The quartz α-β transition temperature in granite is marked by a kink in the thermal expansion curve of the rock, and it is found to increase by 60°C–70°C per 100 MPa confining pressure, as opposed to the published value of 26°C per 100 MPa for single crystals of quartz. Equations are presented which allow calculation of the effects of confining pressure and temperature on the stresses and displacements in and around a spherical inclusion embedded in a matrix of different elasticity and thermal expansion. The theory, together with a simple self-consistent model for granite, accounts semiquantitatively for the observations of thermal expansion and the effect of confining pressure thereon, and for the observed α-β transition temperatures for quartz in granite. 相似文献
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In this paper, several mechanical deformation curves of limestone are reviewed, and the effects of temperature, confining pressure, and fluid are discussed. Generally, Mohr–Coulomb is used for limestone brittle fracture. The characteristic of low temperature cataclastic flow and the conditions and constitutive equations of intracrystal plastic deformation such as dislocation creep, diffusion creep, and superplastic flow are discussed in detail. Specifically, from the macroscopic and microscopic view, inelastic compression deformation (shear-enhanced compaction) of large porosity limestone is elaborated. Compared with other mechanics models and strength equations, the dual porosity (macroporosity and microporosity) model is superior and more consistent with experimental data. Previous research has suffered from a shortage of high temperature and high pressure limestone research; we propose several suggestions to avoid this problem in the future: (1) fluid-rock interaction research; (2) mutual transition between natural conditions and laboratory research; (3) the uniform strength criterion for shear-enhanced compaction deformation; (4) test equipment; and (5) superplastic flow mechanism research. 相似文献
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Weqiang Zhang Qiang Sun Yuliang Zhang Lei Xue Fanfan Kong 《Environmental Earth Sciences》2018,77(9):350
The evolution of porosity and changes in wave velocity in granite after high-temperature treatment has been experimentally investigated in different studies. Statistical analysis of the test results shows that there is a temperature threshold value that leads to variations in porosity and wave velocity. At a temperature that is less than 200 °C, the porosity of granite slowly increases with increases in temperature, while the wave velocity decreases. When the temperature is greater than 200 °C (especially between 400 and 600 °C), the porosity quickly increases, while the wave velocity substantially decreases. The temperature ranges of room temperature to 200 and 200–400 °C correspond to the undamaged state and the micro-damage state, respectively. The results confirm that there is an important link between the variations of physical and mechanical properties in response to thermal treatment. By studying the relationships among rock porosity, wave velocity and temperature, this provides the basis for solving multi-variable coupling problems under high temperatures for the thermal exploitation of petroleum and safe disposal of nuclear waste. 相似文献
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通过采用传统的岩石薄片显微鉴定和现代化扫描、透视电子显微镜、X射线衍射分析、差热分析等方法对9煤至奥灰间隔水层岩石的结构、构造、矿物成分进行了综合测试，微观研究表明，区内9煤至奥灰问地层中铝含量较高，隔水层中泥质岩粘土矿物主要以叶腊石、伊利石、高岭石为主，大部分岩石遇水后稳定，无崩解现象。其中在煤系地层中发现大量叶腊石。初步分析认为是受后期强烈岩浆岩活动影响，发生热液蚀变而形成。通过压汞实验测试了10个隔水层岩样空隙结构，原岩状态下，9煤至奥灰含水层间隔水层空隙度很低，呈现致密状态，因而应具有良好的隔水能力。 相似文献
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岩石受热后的强度,变形破坏特性的微观研究 总被引：1，自引：0，他引：1
本文对砂岩、灰岩、大理岩在不同温度条件下的单轴抗压强度进行了实验研究,并对岩石在各种温度下结构变化进行了镜下分析,探讨了岩石受热后的破裂机理,定性定量地分析了岩石裂纹随温度变化而发展的规律。研究和分析结果表明:在热应力和外应力的作用下,随着温度增加,砂岩单轴抗压强度有增加的趋势,而灰岩、大理石的强度则有所降低。温度对这几种岩石的变形和破坏特性也有很大影响。 相似文献
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Repair mortars with different B/Ag (binder/aggregate) ratios and natural stone were studied in order to understand the influence of limestone aggregate on the properties of mortar and to check the compatibility of repair mortar with a porous limestone. Three different types of mortars with three different aggregate contents were evaluated by using mercury intrusion porosimetry (MIP) and water saturation method (WSM). Changes in density and uniaxial compressive strength as a function of aggregate content were also recorded. For comparison the properties of the porous limestone were also tested, since it is used in monuments and also as aggregate in the mortar. Tested mortars had average porosities of 27.0 % (±2.0), while oolitic limestone has higher average porosity of 32.2 % (±1.9). The limestone has mainly medium and large pore radii (1–100 μm) while the repair mortars even with high aggregate content has predominantly smaller pores. All but one pure repair mortars have higher uniaxial compressive strength than that of the oolitic limestone. The strength decreases while porosity increases with increasing aggregate content. 相似文献
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长期处于变低温环境中的岩石热力学效应主要表现为材料的力学特性参数、热力系数和饱和冻结状态孔隙冰胀系数等随温度改变而发生变化,这种变化对岩体的变形及强度特性均有显著影响。根据变物性参数的非线性热弹性理论,建立了考虑热力系数和冰胀力系数的本构方程,给出了单轴压缩条件下热力效应系数随温度变化的分析格式和确定方法;借助于花岗岩不同低温干燥和饱和冻结状态的单轴压缩试验资料,获得了花岗岩低温热力效应与温度的关系,并探讨了其对花岗岩抗压强度的影响特性。分析表明,在变低温环境下花岗岩热力系数和冰胀力系数均随相对温差的增大而逐渐减小,热力系数降低速率小于冰胀系数降低速率,在同一温差下热力系数大于冰胀系数;热应力和冰胀应力与温度改变量呈非线性增长关系;花岗岩抗压强度在两种状态下均呈增大趋势,但主要以热应力为主,热力系数引起的试样轴向应力增量总是大于冰胀力引起的轴向应力增量。所给方法及研究成果可用于长期处于变低温状态下材料的力学性能研究及其工程应用。 相似文献