共查询到19条相似文献，搜索用时 109 毫秒
1.
基于P-R相关性研究的岩石地基承载力优化取值 总被引：1，自引：0，他引：1
岩石地基承载力是建筑工程中一个重要的力学指标,大多数建筑工程主要依据岩石饱和单轴抗压强度的标准值R确定,重要建筑工程还需要通过岩体载荷试验的承载力特征值P确定,那么两种方法必然存在一定的相关性。实践经验表明,用R确定承载力的方法简单易行,但R代表的是岩石材料的特性,与工程岩体的情况有显然的不同,而原位载荷试验是在半无限条件下进行的,与工程实际条件更为接近,因此,用P确定地基承载力比用R要合理。在总结多达43点的岩体载荷试验及对应部位至少3组的单轴抗压强度对比试验成果与收集248组重庆地区岩石的三轴强度试验成果的基础上,建立了P-R相关关系及围压条件下的强度特征。通过揭示它们之间的相关性,提出采用岩石饱和单轴抗压强度标准值的1.5倍作为地基承载力特征值的重要结论,为岩石地基承载力优化取值提供了重要依据。 相似文献
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岩基载荷试验在设计大直径灌注桩中的应用 总被引：2，自引：0，他引：2
本文分析了目前大直径灌注桩岩基承载力取值方法的现状，并结合岩基载荷试验实例，对ＧＢＪ７－８９规范依据岩石饱和单轴抗压强度确定岩基承载力设计值作了探讨。 相似文献
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通过研究红层软岩风化程度、完整性、饱和单轴抗压强度、结构灵敏性、分散性、胶结系数、崩解性、不同尺度结构类型等工程参数与岩土体结构的关系,提出了岩土"结构稳定性"的工程概念与分析思路,初步建立了由结构类型、风化系数、完整性系数、坚硬程度、崩解模式、结构灵敏度、分散度、胶结系数等工程参数组成的红层岩土结构稳定性综合判别标准,将红层岩土分为结构稳定性强、结构稳定性中等、结构稳定性差三类,为理解红层岩土工程性能、工程安全设计等提供了参考。 相似文献
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用岩石点荷载强度试验并经相关计算得到嵌岩桩桩端持力层岩石的饱和单轴抗压强度标准值,借此判定、核验嵌岩桩的承载力. 相似文献
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软岩旁压试验与单轴抗压试验对比研究 总被引：2，自引：0，他引：2
在我国广泛分布的白垩系至第三系泥质粉砂岩是一种软质岩石,具有较大的地基潜力。按现行规范确定的承载力值往往偏低。在大量试验资料基础上,建立了旁压试验特征参数与岩石单轴抗压强度的相关方程,并同岩基载荷试验进行对比。实践证明,旁压试验是一种有效的原位测试方法,对确定同类地区软岩地基的承载力具有推荐价值和指导意义。 相似文献
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本文进行了不同级配的混凝土圆柱体试样的声弹性试验和单轴压缩试验。通过试验得出不同级配混凝土试样的纵波波速与其单轴抗压强度的关系。试验结果表明,混凝土弹性波幅的衰减与材料的密度和尺寸有关。 相似文献
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某工程蚀变岩孔隙特征及其软弱程度研究 总被引：1，自引：0，他引：1
孔隙作为岩体的初始损伤,对岩体的强度及变形特性的影响尤为明显,而孔隙发育是研究区内一类力学性质较软弱岩石的显著特征。对蚀变岩孔隙特征的研究是了解蚀变岩的软弱程度及孔隙度对其软弱程度的影响的有效方法。针对此蚀变岩进行岩矿及铸体薄片分析得出蚀变岩孔隙有原生、浅表生及构造3种成因,其中以原生为主。从饱水蚀变岩的常规单轴压缩试验应力-应变全过程曲线上求取蚀变岩的饱和单轴抗压强度及割线模量,再与相应试样的孔隙度进行相关性分析,结果显示出蚀变岩的饱和单轴抗压强度及割线模量均随孔隙度的增加而减小,且呈幂函数关系。由于蚀变岩的饱和单轴抗压强度(R c)及割线模量(E s)作为软硬岩评判标准具有一致性,且两者与孔隙度(n)存在较好的相关性,以此将3者共同作为蚀变岩软弱程度的划分标准,并得出软硬岩分界处n为12%、R c为30 M Pa、E s为5 GPa。 相似文献
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Prediction of specific energy of carbonate rock in industrial stones cutting process 总被引：2，自引：2，他引：0
Specific energy (SE) measurements of circular saws were conducted on 12 different carbonate rocks. Rock samples were collected from the factories for laboratory tests. Bulk density, apparent porosity, uniaxial compressive strength, Brazilian tensile strength, flexural strength, Schmidt rebound hardness, Shore hardness, point load strength index, Los Angeles abrasion values, and P-wave velocity values were determined in the laboratory. SE and rock properties were evaluated using simple regression analysis and empirical equations were developed. The equations were verified by statistical tests. Regression analysis showed that high correlations exist between SE and uniaxial compressive strength, Shore and Schmidt hardness, bulk density, apparent porosity, and flexural strength. It was found that the SE value of rocks in cutting process was highest for those rocks having the high density, compressive strength, flexural strength, Schmidt and Shore hardness, point load strength index, and P-wave velocity values. 相似文献
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Relationship Between Petrographic Characteristics and the Engineering Properties of Jurassic Sandstones, Hamedan, Iran 总被引：2，自引：0，他引：2
M. Heidari A. A. Momeni B. Rafiei S. Khodabakhsh M. Torabi-Kaveh 《Rock Mechanics and Rock Engineering》2013,46(5):1091-1101
To study the relationship between engineering properties and petrographic characteristics, 20 rock samples were collected from Jurassic sandstones in the Hamedan region, western Iran. The specimens were tested to determine uniaxial compressive strength, point load strength index, tangent modulus, porosity, and dry and saturated unit weights. Samples were also subjected to petrographic examination, which included the observation of 11 parameters and modal analysis. Based on the results of a statistical analysis, polynomial prediction equations were developed to estimate physical and mechanical properties from petrographic characteristics. The results show that textural characteristics are more important than mineral compositions for predicting engineering characteristics. The packing density, packing proximity and grain shape are the petrographic properties that significantly affect the engineering properties of samples. Multivariate linear regression analysis was performed, employing four steps comprising various combinations of petrographic characteristics for each engineering parameter. The optimal equation, along with the relevant combination of petrographic characteristics for estimating the engineering properties of the rock samples is proposed. 相似文献
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黄土的构度指标及其试验确定方法 总被引：4，自引：4，他引：0
黄土的结构性是一个重要的物理性质指标,它与土的粒度、密度和湿度一起影响土的力学性质。依据加荷、扰动、浸水释放土结构势的方法,由土的无侧限抗压强度定义了黄土结构性的构度指标。通过多个场地不同黄土的无侧限单轴压缩试验,测试分析了不同含水率原状土、重塑土和饱和原状土的单轴压缩应力-应变曲线及无侧限抗压强度变化规律,由此得出土的构度指标的变化规律。并且,在粒度、密度、湿度相似条件下,比较分析了土的构度指标与其压缩性之间的关系。土的构度指标与粒度、密度和湿度指标一起能够合理描述土的物理力学基本性质。 相似文献
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北京有大量采用房山大理岩制造的石质文物,这使得北京大理岩力学性质的研究对于科学指导文物保护和修复具有重要意义。但由于文物本体取样困难,难以获得其力学参数。因此本文对北京大理岩的物理、力学参数进行测试,通过建立物理参数和力学参数的回归方程,实现利用物理参数评价力学参数的目的。以北京大理岩中的青白石和汉白玉为研究对象,对8个边长为150 mm立方体试样进行施密特回弹测试,对40个Ф50 mm×100 mm的圆柱体试样进行里氏硬度、纵波波速测试和单轴压缩试验,得到了大理岩的回弹值、里氏硬度值、纵波波速与单轴抗压强度、弹性模量。分别以单轴抗压强度和弹性模量为因变量,选择单个或两个物理参数作为自变量建立回归方程。通过对比相关系数发现:（1）对于单个物理参数,单轴抗压强度与D探头里氏硬度值的相关性最好,而弹性模量与回弹值的相关性最好;（2）对于两个物理参数,单轴抗压强度（或弹性模量）都与回弹值和D探头里氏硬度值的组合相关性最好。 相似文献
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Manish Kumar Jha A. K. Verma Pradeep Kumar Gautam Anil Negi 《Journal of the Geological Society of India》2017,90(3):267-272
Shale is an important rock due to its suitability for different engineering and scientific applications. Elevated temperature may cause major deformation or damage in shale rock and it may be of irreversible in nature. Such damage have adverse effect on the physicomechnical properties of shale rock. The uniaxial compressive strength and tensile strength of two shales (upper Vindhyan basin, India) have been estimated at elevated temperature using point load strength index method. The rock samples have been analyzed at various temperatures starting from room temperature to 900 °C. The effect of elevated temperature on the physicomechanical properties and their influence on the uniaxial compressive strength has been studied in detail. Damage induced, in both shale have been estimated using compressional wave velocity. The analysis of the experimental result shows that the uniaxial compressive strength decreases from 63.45 to 18.45 MPa and 60.94 to 22.22 MPa, for Jhiri and Ganurgarh shale respectively. Tensile strength of shales have been also estimated. The value of tensile strength decreases from 3.65 to 1.05 MPa and 3.46 to 1.26 MPa respectively for Jhiri and Ganurgarh shale. Multivariate regression analysis has been carried out to obtain the correlation between physicomechanical properties and uniaxial compressive strength of Jhiri and Ganurgarh shale. 相似文献
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充分认识岩石的地质本质性是准确描述其物理力学特性的桥梁。岩石的地质本质性涵盖了岩石的物质性、结构性和赋存状态3个方面的内容。在综合考虑岩石上述3方面特征及其与单轴试验联系的基础上,以矿物组成、密度、纵波波速和含水状态为基本指标,采用回归和BP神经网络的方法对碳酸盐岩单轴抗压强度进行预测,并采用灰色关联分析法验证本研究所选用的预测基本指标的合理性。实例应用表明：本次采用的回归方法对该类岩石强度预测的最大误差为15.3%,BP神经网络方法预测的最大误差为8.5%。预测误差出现的原因为碳酸盐岩物质组成复杂,所选预测基本指标是实际情况的简化,同时泥灰质岩石所具有的膨胀性也导致实测和预测结果具有一定的差异。 相似文献
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The effective porosity, saturated sonic velocity and saturated uniaxial compressive strength were determined on a large number of Borrowdale Volcanic Group volcaniclastic core samples from three boreholes at Sellafield, Cumbria. The work formed part of the UK Nirex Limited site investigation into whether the Sellafield area could be suitable as a repository for intermediate and low level radioactive waste. Most of the intact samples were of low to very low effective porosity, had a high sonic velocity and were very strong to extremely strong. However, a proportion of values deviated significantly from this. Bivariate analysis showed a negative relationship exists between sonic velocity and effective porosity. The cross plots of these two parameters with uniaxial compressive strength showed a wide range of strength values for samples of low effective porosity and high sonic velocity. Six failure types were identified during the uniaxial compressive strength tests. The strongest samples tended to fail through the matrix and the weakest rock samples tended to fail through haematized material or along haematized veins. Effective porosity and sonic velocity measurements could not distinguish between those samples that failed through the matrix and those that failed along discrete narrow veins. The presence of narrow haematized veins has a major effect on the intact rock strength. 相似文献
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冻结盐渍砂土单轴强度特性研究 总被引：5，自引：3，他引：2
通过对兰州盐渍砂土重塑土添加不同量的盐分来模拟不同含盐量的盐渍土, 并对其进行单轴抗压试验, 分析其在不同含盐量、不同温度及不同速率的应变加载情况下, 冻结盐渍砂土的单轴抗压强度的变化规律, 重点讨论了盐分对土体力学参数的影响以及弹性模量与含盐量、温度的关系. 结果表明: 易溶盐含量的增加会导致单轴抗压强度逐渐降低, 试验温度越低抗压强度会越大; 应变加载速率的增加会增大土体的单轴抗压强度, 同时会缩短土体达到应力峰值的时间; 土体含盐量越大弹性模量越小, 温度越低弹性模量越大. 相似文献
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物理相似模型试验是复杂、难采矿技术研究的有效手段,而岩石相似材料物理力学特性的研究是试验有效进行的前提。根据相似原理和岩石的力学特性,论证了岩石相似材料单轴抗压强度的力学代表性。统计并分析了影响岩石相似材料单轴抗压强度的一系列因素,基于量纲分析的方法构建了岩石相似材料单轴抗压强度与砂粒径、配比材料总量、充填材料（砂）用量、水用量、养护方式等重要因素间的无量纲计算模型,结合岩石相似材料配比试验得到了定量关系式。选取3组具有代表性的岩石相似材料配比试验对所建立的单轴抗压强度计算关系式进行验证,其计算结果与实验室实测结果相吻合,平均误差为4.20%,定量关系式在岩石相似材料参数的研究上具有一定的合理性。研究结果可以为相似材料物理力学参数的预测及岩土工程物理模型试验相似材料的高效选取提供参考。 相似文献