Effects of Rock Properties on Specific Cutting Energy in Linear Cutting of Sandstones by Picks

Summary. Specific cutting energy (SE) has been widely used to assess the rock cuttability for mechanical excavation purposes. Some prediction models were developed for SE through correlating rock properties with SE values. However, some of the textural and compositional rock parameters i.e. texture coefficient and feldspar, mafic, and felsic mineral contents were not considered. The present study is to investigate the effects of previously ignored rock parameters along with engineering rock properties on SE. Mineralogical and petrographic analyses, rock mechanics, and linear rock cutting tests were performed on sandstone samples taken from sites around Ankara, Turkey. Relationships between SE and rock properties were evaluated using bivariate correlation and linear regression analyses. The tests and subsequent analyses revealed that the texture coefficient and feldspar content of sandstones affected rock cuttability, evidenced by significant correlations between these parameters and SE at a 90% confidence level. Felsic and mafic mineral contents of sandstones did not exhibit any statistically significant correlation against SE. Cementation coefficient, effective porosity, and pore volume had good correlations against SE. Poisson’s ratio, Brazilian tensile strength, Shore scleroscope hardness, Schmidt hammer hardness, dry density, and point load strength index showed very strong linear correlations against SE at confidence levels of 95% and above, all of which were also found suitable to be used in predicting SE individually, depending on the results of regression analysis, ANOVA, Student’s t-tests, and R² values. Poisson’s ratio exhibited the highest correlation with SE and seemed to be the most reliable SE prediction tool in sandstones.     

Correlation analysis and partial least square modeling to quantify typical minerals with Chang＇E-3 visible and near-infrared imaging spectrometer＇s ground validation data

In 2013, Chang＇E-3 program will develop lunar mineral resources in-situ detection. A Visible and Near-infrared Imaging Spectrometer （VNIS） has been selected as one payload of CE-3 lunar rover to achieve this goal. It is critical and urgent to evaluate VNIS＇ spectrum data quality and validate quantification methods for mineral composition before its launch. Ground validation experiment of VNIS was carried out to complete the two goals, by simulating CE-3 lunar rover＇s detection environment on lunar surface in the laboratory. Based on the hyperspectral reflectance data derived, Correlation Analysis and Partial Least Square （CA-PLS） algorithm is applied to predict abundance of four lunar typical minerals （pyroxene, plagioclase, ilmenite and olivine） in their mixture. We firstly selected a set of VNIS＇ spectral parameters which highly correlated with minerals＇ abundance by correlation analysis （CA）, and then stepwise regression method was used to find out spectral parameters which make the largest contri- butions to the mineral contents. At last, functions were derived to link minerals＇ abundance and spectral parameters by partial least square （PLS） algorithm. Not considering the effect of maturity, agglutinate and Fe~, we found that there are wonderful correlations between these four minerals and VNIS＇ spectral parameters, e.g. the abundance of pyroxene correlates positively with the mixture＇s absorption depth, the value of absorption depth added as the in- creasing of pyroxene＇s abundance. But the abundance of plagioclase correlates negatively with the spectral parame- ters of band ratio, the value of band ratio would decrease when the abundance of plagioclase increased. Similar to plagioclase, the abundance of ilmenite and olivine has a negative correlation with the mixture＇s reflectance data, if the abundance of ilmenite or olivine increase, the reflectance values of the mixture will decrease. Through model validation, better estimates of pyroxene, plagioclase and ilmenite＇s abundances are given. It is concluded that VNIS has the capability to be applied on lunar minerals＇ identification, and CA-PLS algorithm has the potential to be used on lunar surface＇s in-situ detection for minerals＇ abundance prediction.     

风化面、荒漠漆及地衣在岩矿表面对高光谱遥感的影响

地表风化产生的表面覆盖层、风吹送的尘埃、胶结物或附着物在岩矿表面形成的外壳是影响地表高光谱遥感识别和反演的重要和关键因素。本研究区位于干旱缺水的新疆西准噶尔包古图地区,对岩矿表面的风化面、胶结物形成的荒漠漆、附着于岩面的地衣和原岩的新鲜面进行了波谱测定分析、X射线荧光元素分析和光薄片镜下观察。结果表明：该地区的大部分岩石表面有风化层覆盖,主要为物理风化,少部分岩石表面发生了化学风化;荒漠漆波谱在可见光波段改变原岩本身的波谱形态,但在短波红外波段,保持原岩波谱特征只改变了反射率大小,并不影响对原岩矿物质的高光谱探测;地衣附着于岩表的波谱特征不仅改变了波谱反射率,还完全改变了原岩的波谱形态,对原岩表面波谱有混淆干扰作用。岩矿表面的研究是波谱测量从实验室走向野外实际应用的基础,也是利用高光谱遥感技术直接进行矿物识别、相似矿物的区分以及提取矿物含量和化学成分研究的最初和关键一步。     

莺琼盆地重点区带深层储层岩石力学参数求取及意义

莺琼盆地中新统是油气勘探开发的重点层系,但海上区块深层储层取心极少,岩石力学参数研究较为薄弱。针对这种现状,文章基于声波全波列测井曲线,计算岩石动态力学参数;利用全岩矿物、物性分析以及压汞实验资料,分析岩石力学参数的影响因素。结果表明：研究区中新统储层杨氏模量介于20~50 GPa之间,泊松比介于0.1~0.35之间,内摩擦角介于20°~35°之间,抗张强度介于5~30 MPa之间。横向上,同一层位各岩石力学参数之间具有非均一性;垂向上,岩石力学参数与埋深呈弱正相关性。影响因素分析表明,岩石孔隙度、粘土矿物含量、脆性矿物含量以及孔隙半径影响岩石力学参数大小。研究成果一方面为该区地应力场模拟、储层裂缝评价以及目的层压裂优化设计提供了可靠的基础数据;另一方面,为衔接深部储层地质参数与地质力学参数评价提供了理论依据。     

Studies on the reflectance spectral features of saline soil along the middle reaches of Tarim River: a case study in Xinjiang Autonomous Region, China

There has been growing interest in the use of reflectance spectroscopy as a rapid and inexpensive tool for soil characterization. In this study, 53 soil samples were collected from the oasis in the Weigan and Kuqa River delta along the middle reaches of Tarim River to investigate the level of soil chemical components in relation to soil spectral. An approach combining spectral technology and multi-variant statistical analysis was used to determine the reflectance spectral features of saline soil. The spectral data was first pretreated to remove noises and absorption bands from water, which eliminated influence from instrument errors and other external background factors. Several spectral absorption features were calculated for several saline soil samples to confirm that soil at the same salinity level had similar absorption spectral properties. Secondly, a correlation relationship between reflectance spectra and salinity factors was estimated by bivariate correlation method. Fourteen salinity factors including eight major ions and soil electrical conductivity (EC), soil salt content (SSC), pH, and total dissolved solid (TDS) in the saline soil were evaluated. Datasets of the salinity factors that correlated significantly with field data measurements of reflectance rate and the corresponding spectrum data were used to construct quantitative regression models. According to the multiple linear regression analysis, SSC, SO₄ ^2?, TDS, and EC had a correlation coefficient at 0.746, 0.908, 0.798, and 0.933 with the raw spectral data, respectively, which confirmed strong correlation between salinity factors and soil reflectance spectrum. Findings from this study will have significant impact on characterization of spectral features of saline soil in oasis in arid land.     

Mechanism of the Mudstone Tunnel Failures Induced by Expansive Clay Minerals

Expansive clay minerals can be a serious threat to underground rock structure because of their swelling behavior when absorbing water. Roof and wall collapse as well as large deformation were observed in Xiaotun Coal Mine, Guizhou Province, China. This paper studies the characteristics of expansive clays in order to understand the mechanism of the mudstone tunnel failures in the mine. The physical and mechanical properties of the tunnel surrounding rock samples, including mudstone, silty mudstone, argillaceous siltstone and fine sandstone were determined. X-ray diffraction analysis was conducted to determine the mineralogical composition while the scanning electron microscope was used to examine the internal structure of the different samples. The results indicate that the illite–smectite and the montmorillonite are the main minerals composing the rock samples. A series of micro-cracks and pores occur in the samples which suggest a good hydraulic conductivity. The results indicate that the mudstone has poorer mechanical properties in comparison to the fine sandstone. Also, the Flac3D numerical simulations were conducted and it was shown that the large deformations were consistent with the field observation due to weak mechanical properties of the surrounding rock under seepage action especially with the increase of water head and porosity. It is concluded that internal structure and mechanical strength of the mudstone is weakened by the illite–smectite and the montmorillonite mineral content as well as the combined action of underground water causing physical disintegration.     

砒砂岩化学成分特征对重力侵蚀的影响

本文以内蒙南部砒砂岩的重力侵蚀为例,研究岩石化学成分与重力侵蚀发育的主要控制因素抗剪强度的之间关系。通过对砒砂岩样品的化学成分、矿物组成、力学性质等参数的测试和试验结果,利用化学蚀变指数(CIA)阐明了岩石的风化程度,分析了岩石中不稳定的化学成分在水的作用下,对岩石的化学风化作用和岩石强度的影响。并对砒砂岩的化学成分含量与其内聚力进行两两相关分析和多元相关分析。这些对砒砂岩区基岩的重力侵蚀机理研究具有一定的参考价值。     

Predicting the Building Stone Cutting Rate Based on Rock Properties and Device Pullback Amperage in Quarries Using M5P Model Tree

One of the key parameters that affect the selection of equipment and the cost estimation of dimension stone quarries is the rock cutting rate or production rate. In this study, the M5P tree algorithm is used to determine the relationship between the hard rock sawability and its factors especially the physical and mechanical characteristics of rock. To achieve the research goal, a variety of eleven types of hard dimension stone were selected and nine major physical and mechanical characteristics of rock including uniaxial compressive strength, Young’s modulus, Brazilian tensile strength, equivalent quarts content, grain size, Mohs hardness, point load test, density and P-wave velocity of these samples were evaluated. The cutting rate of diamond wire for all of the Workpiece was measured at different pullback amperage with a fully instrumented cutting platform in laboratory. All operational parameters of cutting process were entirely controlled. Thus, a database containing 99 datasets was provided and it has been used for analyses. The obtained results from the pruned and unpruned tree models showed a significant relationship between cutting rate and its factors. In the end, the results of M5P tree method were compared with statistical analyses (i.e., linear and nonlinear regression). The coefficient of determination be equal with 0.92, 0.86, 0.77 and 0.63 for unpruned tree, pruned tree, linear and nonlinear regression method respectively. This comparison showed that the both method of M5P tree technique have a better performance in predicting the cutting rate rather than the statistical regression methods.     

河南小秦岭金矿区方铅矿的远红外反射光谱

以天然形成的方铅矿晶体为研究对象,说明方铅矿远红外反射光谱中低频端Plasmon反射边产生的物理原因,并根据不同反射边的斜率(Va)值大小与样品中所含杂质量的相关性,以解释不同样品中不同组分和结构上的特点对Plasmon反射边的影响。且根据不同杂质的正负相关性在自然成因上的因果关系,证明从反射光诸结构中获得对矿物成因有一定指导意义的信息的可行性。     

碎屑砂岩三轴压缩下强度和变形特性试验研究

基于碎屑岩组织结构疏松、含水率较高、物理力学性能较差、呈孔隙式胶结接触等特点,对碎屑砂岩首先开展了物理特性试验分析,认为其微、细观结构复杂、内部破坏严重,矿物成分为石英、长石、绢云母等,化学成分以SiO2为主,属微透水、小孔隙率砂岩,且渗水化学侵蚀并不显著。其次,开展了静水压力、单轴压缩和三轴压缩试验,研究了碎屑砂岩的强度和变形破坏特性。最后,初步探索了物理特性与强度变形特性的关系。结果表明,静水压力为2.6 MPa时,岩样内部微缺陷压密完成;单轴压缩曲线呈明显6阶段特征,峰值应力达0.98 MPa,属脆-延性破坏;三轴压缩条件下,岩样呈压缩为主的延性扩容破坏,轴向压缩和环向体积扩容达6%和4%;曲线无明显破坏荷载,呈现非线性、塑性硬化、存在屈服平台和体积由压缩向扩容过渡等特性。且体积扩容破损应力与屈服应力基本相同,扩容转折点随围压增加而增大,围压可增强岩样抵抗变形破坏的能力。试验结果旨在为岩石工程稳定分析及本构模型构建提供可靠的依据。     

颐和园万寿山岩石物理力学试验与岩矿分析

颐和园是世界文化遗产,其万寿山山体既是文物本体,也是建筑、题刻等文物和草木的载体,保护万寿山及其承载的文物,首先需要对万寿山山体的特征和岩体特性进行调查和研究。本文在查阅万寿山地质成因的基础上,测量了岩层的产状和多处裸露岩石的回弹值。对现场散落岩块进行了密度、抗拉强度、抗压强度、抗剪强度等物理力学指标测试。选取典型岩块,开展薄片、光片和电镜扫描等测试分析其矿物成分,获得了万寿山岩石矿物组成与含量比例。以上试验和测试成果是后期万寿山山体工程地质研究和石质文物保护的理论依据,具有重要的理论意义和广泛的应用价值。     

Correlation of mineralogical and textural characteristics with engineering properties of selected granitic rocks from Turkey

Granitic rocks show a variety of engineering properties that may affect quarrying operations, tunneling, mining, slope stability and the use of rock as a construction material. The physical and mechanical properties are a function of the mineralogical and textural characteristics of the rock. The purpose of this study is to apply correlation analysis to investigate the relationships between petrographical and engineering properties of granitic rocks. A variety of granitic rock samples from different parts of Turkey were subjected to petrographic studies. The same samples were then tested to determine specific gravity, dry and saturated unit weight, water absorption, effective and total porosity, sonic velocity, Schmidt hardness, point load strength index, uniaxial compressive strength, tensile strength and modulus of elasticity. The relationships between these properties and the petrographical characteristics are described by simple regression analyses. The study revealed that the influence of the textural characteristics on the engineering properties appears to be more important than the mineralogy. It also determined that the types of contacts, grain (mineral) shape and size significantly influence the engineering properties of the granitic rocks.     

Abrasivity Assessment of Granitic Building Stones in Relation to Diamond Tool Wear Rate Using Mineralogy-Based Rock Hardness Indexes

The objective of the present study was to determine the abrasive wear potential of granites in circular sawing using some mineralogy-based rock hardness indexes. A literature study indicated that little or no attention has been given to assessing this kind of relationship in the field of stone processing. To accomplish this objective, sawing experiments were performed on nine different granites used widely as building and decorative stone materials. The measured sawblade-specific wear rates were correlated with three different rock hardness indexes attained by combining the percentage content of hard mineral constituents with their known hardness values. Statistical analysis of the experimental data revealed that rock hardness indexes that are based on both Vickers hardness number and Rosiwal hardness could be accepted as reliable indicators of granite abrasivity. These two indexes were also found to correlate well with the average power drawn during the process. However, the rock abrasivity index based on Mohs relative scratch hardness did not show statistically significant correlations with sawblade wear rate and power drawn. Although quartz percentage content is regarded as an important abrasivity parameter by practitioners, the observations made here indicate that consideration of quartz percentage content alone is not sufficient to describe the abrasive potential of granites, and thus incorporation of other hard mineral constituents could be more suitable.     

基于岩石地质本质性的碳酸盐岩单轴抗压强度预测

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。     

广东两类花岗岩的反射光谱特征及其遥感意义

地物波谱信息是多光谱遥感的基础、光谱信息所具有的特征反映了地物本身的存在、变化和差异。作为花岗岩岩石物理特性研究的一部分，笔者选择了广东早古生代两类花岗岩为研究对象测定并分析了两类花岗石及其围岩的反射光谱特征，并且依据它们光谱特性的差异。确定了遥感图象处理的技术和方法，为下一步该地区遥感图象识别花岗岩奠定了基础。     

A quantitative weathering classification system for yellow travertines

Weathering can cause adverse effects on the physico-mechanical properties of rocks. Although the processes and outcomes of weathering have been investigated for many rock types, the travertine weathering was not paid enough attention as much as the others. However, the unfavorable effects of weathering may arise rapidly due to travertine’s calcium carbonate composition and highly porous texture. Travertine is an important rock type in building stone market and is generally preferred as an exterior façade material. This rock type was also used in many historical buildings and sculptures in the past, and the signs of extensive weathering can be recognized on some of these travertine-made structures. In this study, it was aimed to characterize the effect of weathering on travertine’s structural properties. The yellow travertine from Eskipazar (Karabuk, Turkey) was selected as the study material and the samples with different weathering degrees were collected from site. The chemical, physical and mechanical properties of those samples were determined in laboratory. The physico-mechanical variations with progressive weathering grades were statistically evaluated and a weathering classification based on a rating system was proposed for yellow travertine in rock material scale. The newly developed system may assist in characterizing the degree of weathering for historical structures built by yellow travertine. Additionally, the classification may also guide to further researches on the weathering of different types of travertine.     

岩石矿物细胞元随机性参数赋值方法研究

数值计算中利用随机分布对各单元赋予不同的物理力学参数来考虑岩石的非均质性,赋值过程是纯随机的,并没有考虑岩石矿物组成的结构特征。故提出一种新的岩石非均质参数赋值方法--岩石矿物细胞元随机性参数赋值方法,基于岩石矿物种类及其含量定义细胞元类别判定区间,利用Monte Carlo方法对各个细胞元进行矿物类别判定,并进行相应的参数赋值,通过各矿物细胞元的随机混合体来描述岩石的非均质性。该方法既考虑了组成岩石的矿物种类及其含量（结构特征）,又考虑了组成矿物在岩石中的随机分布特征。针对矿物分布的随机特征,利用两矿物细胞元混合模型和三矿物细胞元混合模型进行数值试验,研究了矿物细胞元随机分布特征对岩石宏观力学参数的影响。研究结果表明,岩石矿物细胞元随机性参数赋值方法具有结构性和随机性的双重特性,其随机性不依赖于随机参数,岩石宏观力学参数受细胞元随机性特征的影响很小。     

新疆谢米斯台地区岩矿光谱特征提取及光谱分析

不同岩石矿物和矿化蚀变具有不同的光谱特征, 这是利用遥感技术进行岩石矿物和蚀变信息识别的基础。本研究在谢米斯台地区进行岩矿样品采集, 利用ASD野外光谱辐射仪采集光谱反射率数据, 通过去噪处理、标准化处理、微分处理和去包络线处理, 开展了典型岩矿样品、风化面与新鲜面样品和不同矿化蚀变的光谱特征提取和光谱分析。研究发现, 岩矿在380~1 100 nm波段的光谱特征, 主要是金属离子产生;在1 100~2 500 nm波段的光谱特征, 主要是阴离子基团中的羟基、碳酸根和水分子产生;矿化蚀变光谱具有可诊断性特征谱带, 是其矿物组成中的各种蚀变矿物特征信息的反映;受到矿物含量改变和外界环境因素的影响, 光谱的整体形态或局部特征都发生变化。岩矿光谱特征的提取和分析, 将提高和改善高光谱技术对不同区域同种类型的矿床勘查。     

基于数字图像分析的冰水堆积体结构建模与力学参数研究

冰水堆积体是一种典型的混合介质,由软弱“土”与坚硬“石”构成,其参数选取和分析方法困难。利用数字图像重构方法模拟冰水堆积体结构特征,可反映块石分布特征;以基于图像识别的块石分割和颗粒离散元建模分析方法,研究了堆积体内介质分布、土体颗粒强度对混合介质力学参数的影响规律,分析了冰水堆积体变形、峰值抗剪强度及峰后段抗剪强度的变化规律。结果表明：冰水堆积体混合介质在峰值前的变形曲线呈非线性硬化性,峰后呈现塑性特性,其综合抗剪摩擦角随基质土的黏结强度提高而降低;当块石含量小于25%时,抗剪切强度近似等于基质土强度,块石含量高于25%时,抗剪切强度随块石含量增加而提高;由于受块石空间分布影响,块石含量与摩擦角间的相关性要比其与黏结强度间的高;该成果应用于云南古水水电站坝前冰水堆积体发现,含块石混合介质内摩擦角比纯土高0°～8°,与工程判断较吻合。该方法能弥补室内试验不能考虑大尺寸块石的困难,可作为室内试验获取力学参数方法的有益补充。     

昌化鸡血石的宝石学研究

利用X射线粉末衍射仪、拉曼光谱仪、扫描电子显微镜、电子探针及岩石薄片对昌化鸡血石样品中“地”与“血”的矿物组成、形貌特征、化学成分等进行了研究。结果表明,昌化鸡血石“硬地”“软地”与“冻地”的矿物组合不同;其中,“地”以地开石为主且呈鳞片状,随着石英的增加,特别是明矾石的加入,“地”的硬度变大。“冻地”鸡血石中地开石的结晶粒度比“硬地”鸡血石中的大,但其空间定向性排列没有后者的好。昌化鸡血石中“血”由细小的半自形-他形辰砂微晶集合体组成,其“血”色与辰砂晶体的聚集状态及其杂质成分有关,而杂质成分又与Se元素的质量分数密切相关。