Physico-thermal and mechanical properties of Sanliurfa limestone,Turkey

Sanliurfa limestone is becoming increasingly popular for both interior and exterior building applications in the local area in south east Turkey, being easy to cut and shape and suitable for many purposes. Although these limestones are low cost construction materials, they are not widely used elsewhere due to the lack of data regarding their chemical, physico-thermal and mechanical properties and the requirement for highly skilled labour. A total of 264 samples of Sanliurfa limestone from four quarries were tested to determine their physico-thermal and mechanical properties. The data obtained confirmed they satisfy the main international standards for the use of limestone in the construction industry.     

岩石风化程度特征指标的分析研究

岩石风化程度的划分及工程特性研究，对于工程基础面高程的选择以及工程环境或工程材料的利用具有重要意义。关于岩石风化程度划分目前多是采用工程地质定性评价方法，依赖定性的不确定判据进行岩石风化程度划分带有很大随意性。因此，研究和发展定量分析评价方法是必要的。岩石经过风化作用，形成的风化裂隙具有无方向性、不规则发育等特点，与构造作用形成的微裂隙有着本质区别；风化作用改变了岩石的矿物成分，岩石在风化过程中表现出来的阶段性，反映了岩石的不同风化程度。基于对风化岩石显微裂隙的发育状况及其次生充填特点、长石蚀变性质、粘土矿物成分变化等定性资料的分析研究，给出了定量化的统计，建立了岩石风化程度划分的判据。给出的定量指标很好地反映了风化岩石质量，且与反映岩石风化程度的一些物理力学指标存在良好相关性。     

岩石的风化损伤属性与缩小防护煤柱开采机制研究

以大量试验数据、现场测试资料和大规模缩小防护煤柱开采工程实践为依据,研究隐伏煤田基岩风化带的分布特点。结果表明:岩石风化损伤后具有强度降低,塑变能力增强;多趋泥化,裂隙易于弥合,再生隔水能力显著增强,亲水能力强等变异特征以及工程地质特性。重点论述风化带内煤层开采具有移动快、变形大、回缩快和下沉大等覆岩破坏移动演化新特征,获得以泥质岩类为主的风化带岩层受开采扰动的影响,具有阻隔底含水下渗和抑制导水裂隙带继续发展的双重作用和煤岩柱厚度与风化程度是影响导水裂隙带发育高度的主导因素等新的认识。同时,阐述了缩小防护煤柱开采的机制,系统地提出了采空区滞后控水、煤水分流、加大开采高度、物探预测和地质弱面预先加固等一系列确保安全的关键技术保障措施。对类似矿井浅部资源的回收与安全开采具有理论意义和应用价值。     

Creep and time-dependent damage in argillaceous rocks

This paper presents the results of laboratory tests on the time-dependent behaviour of three rocks characterized by a high proportion of clay particles. The viscosity of these sedimentary rocks was studied under different loading conditions in uniaxial compression: static or cyclic creep tests and quasistatic tests (low-loading strain rate) were performed across various orientations of fabric planes.The quasistatic tests showed similarities in the mechanical response of these three argillaceous rocks: a late phase of dilation and a linear development of volumetric deformation before the beginning of unstable crack propagation. The development of secondary and tertiary creep phases during the creep tests highlighted the existence of a deviatoric stress threshold, below which only primary creep is observed. Long-term creep tests also showed that the volumetric variation is not constant during the development of viscoplastic deformations.A microstructural analysis of thin sections extracted from specimens after the tests, gave evidence of cataclastic and granular creep. Damage to the argillaceous matrix occurs and no cracks were observed in the quartz and carbonate grains. This evidence was also demonstrated for tests with loading at a high strain rate.Finally, this study highlights the significant viscoplasticity of argillaceous rocks. The mechanical properties deteriorate rapidly when crack propagation becomes unstable and the viscoplastic strains seem to be due to clay particle slips, known as granular creep.     

Engineering aspects of limestone weathering in Istanbul, Turkey

 Devonian limestones are widespread in the eastern part of Istanbul, Turkey. To assess the influence of weathering on the geological and geomechanical characteristics of these rocks, research was carried out on some profiles from the study area. Field observations show that the weathering has been rapid and the bedrock has been weathered to a depth of up to 8 m. A model for the weathering of limestones is established and modifications proposed to the material and mass weathering schemes for characterisation of the limestone for engineering uses, as both foundation and construction material. The paper also presents the results of field and laboratory investigations, including weathering characteristics and physical and mechanical properties. Interrelationships were determined for all test results. It is concluded that chemical characteristics and the porosity are good indicators of weathering. Received: 10 July 1999 · Accepted: 17 September 1999     

三峡库区奉节县新城区T2b3泥质灰岩斜坡变形破坏模式的现象学研究

三峡库区奉节县新城区边坡,由于其变形破坏的成因机制和破坏堆积体的特殊性质,成为三峡库区地质灾害防治和边坡防护工程的重中之重,其主要地层“巴东组”第3段泥质灰岩也成为学术界和工程界多年来争论的焦点问题之一。通过现象学的研究方法,对泥质灰岩边坡变形破坏成因机制得到如下认识:(1)“巴东组”第3段泥质灰岩岩性脆且易碎,“渗入性”风化导致了大范围岩体强度降低并形成“酥松”结构;(2)边坡岩层通过切层压裂和沿陡倾和中倾节理的重力滑移剪切破坏,形成岩层的结构松动和逐级错动的重力弯曲现象,使边坡岩体的结构强度显著降低;(3)“巴东组”第3段泥质灰岩边坡破坏所形成的堆积物成分均一、完全无规则排列、无滑坡滑动面(带),不是滑坡和崩塌堆积物,而是边坡一定范围结构崩溃解体的产物;(4)“巴东组”第3段泥质灰岩边坡的变形破坏过程是由于风化引起岩石力学性质弱化和重力变形导致岩体结构松动,直至整体结构崩溃的复合过程。     

Applicability of the geological strength index (GSI) classification for very weak and sheared rock masses. The case of the Athens Schist Formation

 The Athens Schist Formation includes a wide variety of metasedimentary rocks, varying from strong or medium strong rocks such as sericite metasandstone, limestone, greywacke, sericite schist through to weak rocks such as metasiltstone, clayey and silty shale and phyllite. The overall rock mass is highly heterogeneous and anisotropic owing to the combined effect of advanced weathering and severe tectonic stressing that gave rise to intense folding and shearing followed by extensional faulting, which resulted in highly weathered rock masses and numerous shear and/or mylonite zones with distinct downgraded engineering properties. This paper is focused on the applicability of the GSI classification system to these highly heterogeneous rock masses and proposes an extension of the GSI system to account for the foliated or laminated weak rocks in the lower range of its applicability. Received: 5 March 1998 · Accepted: 13 July 1998     

Stress ratio effect on fatigue life of tropically weathered rock

This paper investigates the fatigue life of weathered granite and weathered sandstone using a stress ratio of R = 0.17. A small stress ratio is adopted to control data discrepancy between weathered rocks for which stress amplitude is known to affect the fatigue life. The range of varying static strength between weathered rocks, especially for highly weathered rock (grade IV) which has lower static strength, resulted in adopting this small stress ratio. The details of rocks tested, including microscopic petrographic characterization as well as their physical properties obtained from laboratory work, is also explained in this paper. Weathered rock specimens from slightly weathered to highly weathered (grade II, grade III and grade IV) granite and sandstone were used during the investigation. The specimens were representative of rock collected in Sungai Buloh (granite) and Puncak Perdana (sandstone) in Selangor, Malaysia. In order to eliminate the influence of frequency and waveform, all rock specimens (54 in total) were tested under a cyclic compression load with a frequency of 1 Hz using a constant sinusoidal waveform. Result shows that grade IV specimens are the least affected by the small cyclic stress ratio as compared to grade II and grade III specimens. The number of cycles to failure is not dependent on rock weathering grade; it is greatly related to the petrological and microstructure of the individual rock. However, the weathering degree of a rock does contribute to the weakening of the rock's structure, consequently affecting the life of the rock.     

滇中泥质粉砂岩崩解特性试验研究

为了研究滇中泥质粉砂岩的崩解特性,对不同风化程度的泥质粉砂岩进行了静态崩解试验、室内环境崩解试验和耐崩解试验。试验结果表明:岩石风化程度越高,崩解越剧烈;强风化状态的泥质粉砂岩在第四次循环后基本崩解完全,耐崩解系数Id2为46.2～61.8;弱风化和微风化泥质粉砂岩在第二、第三次循环崩解开始加剧,耐崩解系数Id2分别为61.1～73.6和79.5～85.4;崩解物以0.5～2mm和小于0.25mm颗粒物为主。泥质粉砂岩的崩解是由岩石浸水膨胀、胶结物溶解和干湿循环产生的拉应力与张应力共同引起的。     

Automatic monitoring of rotary-percussive drilling for ground characterization—illustrated by a case example in Hong Kong

In mountainous regions comprising weathered soils and rocks, it is important to delineate the spatial distributions of geomaterials with different weathering and decomposition grades in depth. This paper presents a methodology to cost-effectively and accurately identify the subsurface zones of volcanic weathering. The methodology consists of in situ digital monitoring and a number of associated data analysis methods. The in situ digital technique is the drilling process monitor. It can automatically, objectively and continuously measure and record parameters associated with the full drilling process of a rotary-percussion drilling machine when it is being used to drill a production hole (such as probe holes and soil nail holes) in the ground. The data analysis methods are used to identify relevant factual data from the full drilling process data for zoning. The calculations are simple and straightforward tasks. Factual data presented in the paper illustrate that the proposed methodology can be a simple and cost-effective tool to record and utilize by-products of current normal drilling practice for ground investigation, geotechnical design and verifications, drilling construction management, as well as drilling quality control. The proposed methodology offers great potential in furthering the geotechnical knowledge and engineering practice in Hong Kong and many other mountainous regions comprising weathered soils and rocks. There is also significant potential for other applications in civil and mining engineering through estimation of the mechanical properties of rock from the monitored drilling data.     

某工程岩溶桩基分析处理

某９层框剪结构商住楼，采用挖孔桩基础，持力层为微风化石灰岩，超前钻揭示桩底有溶洞溶洞大小不等，首先分析了溶洞发育状况尤其是石灰岩质坚硬寒带程度、岸芯取经（ＢＱＤ）、再根据桩基荷载，对溶洞顶板进行了抗冲切、抗剪及抗弯验算，提出了相应处理方案，经实践及沉降观测证明是正确的。     

岩石变形与渗透率演化关系研究

针对带压开采煤层底板岩层阻水性问题,进行底板岩体试样伺服渗透试验,分析了岩体试样渗透率与变形破坏演化相互关系.结果表明,全应力-应变过程岩样渗透率可划分为原始空隙渗透率和加载破坏渗透率两种,在压密-弹性段内,岩石的渗透率多表现为原始空隙渗透率,稳定破裂-裂纹扩展段内,则多表现为加载破坏渗透率;岩石突增点处应力、应变为峰...     

泉州地区花岗岩残积土地质特征与岩土工程评价

泉州地区广泛分布的花岗岩残积土,由变质-混合岩、酸性-中酸性火山岩和花岗岩风化而成,是一种成分复杂、物理力学指标变化区间很大的特殊性土体,其工程性质主要受母岩及其风化程度的影响,与风化残积物中的成分、结构,特别是粗颗粒含量关系密切,并具有随深度规律变化的特征。本文所称的花岗岩属花岗岩类岩石,包括变质-混合花岗岩、酸性-...     

肯尼亚中风化响岩骨料对混凝土性能的影响研究

针对肯尼亚中风化响岩技术指标不良的现状,通过对拌合物性能、力学性能、电通量和氯离子渗透系数等的测试,研究了中风化响岩对混凝土性能的影响.结果显示:采用肯尼亚中风化响岩配制的混凝土,在相同的配合比条件下,初始坍落度和扩展度均较普通石灰石骨料混凝土小,经时损失相对较大,抗压强度和弹性模量低,但是仍然满足一般工程对混凝土力学...     

Comparison of the static and dynamic elastic modulus in carbonate rocks

Young’s modulus is one of the most important mechanical parameters in building materials used to assess both the appropriateness of a material as well as its mechanical stability. The paper reports a study to predict the elastic modulus for ten carbonate rocks using the ultrasonic technique. The rocks varied from homogeneous limestones to rocks with abundant stylolite, veins and fissures and were subjected to both salt crystallization and thermal weathering tests in order to modify the number and features of their discontinuities. The dynamic and static elastic moduli were measured in both weathered and unweathered samples. The results confirmed the poor relationship between the static and dynamic moduli for the studied rocks. A new equation is proposed which uses both dynamic elastic modulus and spatial attenuation of compressive waves to provide an accurate prediction of static Young’s modulus. As spatial attenuation is highly sensitive to the presence of rock defects, the correlation is very useful for rocks with fractures, voids and/or which have suffered weathering.     

输电线路强风化软岩挖孔基础抗拔试验研究

山区风化程度高的岩基塔位采用挖孔基础,包括直柱挖孔桩、坛子型嵌固、扩底掏挖等3种模型。通过在强风化软岩中开展17组不同模型的挖孔基础上拔试验,分析基础承载性能与破坏机理。荷载位移曲线表明:浅埋时基础呈线性状态分布,深埋时呈缓变型分布;地表竖向位移变化规律表明,基础周围出现显著裂缝表征着基础即将整体破坏,破坏状态为基础本体与周围土体被整体拔出,基础发生整体剪切破坏;基础破裂角随埋深迅速降低,但达到一定埋深后破裂角基本不变;强风化软岩的岩石等代极限剪切强度取32kPa;以单位体积混凝土能承担的上拔承载力为准进行经济性分析,扩底掏挖型模型的经济效益显著。     

Mechanical characterization of small shale samples subjected to fluid exposure using the inclined direct shear testing device

The mechanical strength, elastic moduli, and other properties of shale are known to be highly sensitive to any variation in pore fluid content and pore fluid chemical composition. To date, all existing rock mechanics testing procedures and studies attempting to quantitatively quantify these changes employ standard methods and techniques, i.e., shale testing under hydrostatic confinement, triaxial tests, or direct shear tests, which require very long fluid circulation time due to the intrinsic low hydraulic permeability and low solute diffusivity of shale rocks and large sample size recommended by these conventional methods. Moreover, standard-size samples for conventional rock testing methods are not always available, and the use of non-conventional size samples is sometimes required. In this work, shale testing and results on rock sample the size and shape of a stack of a few pennies are presented. The inclined direct shear test, an innovative patent-pending testing method for small and thin rock specimens, has been developed to facilitate mechanical strength characterization under variable confining pressure, with tested material exposed to different fluids at any desired exposure time, while dynamic elastic moduli can be simultaneously monitored as functions of applied stress state. This device has been compared to standard triaxial test with excellent results. Practical applications using the inclined direct shear testing device (IDSTD^TM) for three shale rocks of different natures are also presented herein.     

水化学溶液及冻融耦合作用下灰岩力学特性试验研究

 以洛阳龙门石窟灰岩为研究对象,考虑石窟区灰岩渗水溶液的侵蚀和冬季冻融损伤的影响,进行不同水化学溶液及冻融耦合作用下的力学试验,研究龙门石窟灰岩在水化学溶液及冻融耦合作用下的力学损伤特征。试验表明,水化学溶液及冻融耦合侵蚀作用下,随着冻融循环次数的增多,灰岩的损伤逐渐增大;与水化学溶液单一的侵蚀作用相比,水化学溶液及冻融耦合侵蚀作用对岩石的损伤程度要大,如在相同的冻融循环次数(90次)的情况下,在蒸馏水、龙门水、NaCl溶液与冻融耦合作用下,试件的强度比自然状态分别下降了50.73%,54.92%,57.67%,而仅受上述溶液作用没有经历冻融的试件强度则分别下降了21.58%,22.88%和28.72%。在试验研究范围内,龙门石窟灰岩的冻融劣化模式均为颗粒损失模式。分析指出,水化学溶液及冻融耦合侵蚀作用下,溶液中凝结核的丰度和溶液的pH值是影响灰岩损伤程度的重要因素。在对试验结果分析的基础上,建立水化学溶液及冻融耦合作用下龙门石窟灰岩的侵蚀损伤方程。研究结果将为石质文物及岩石工程的长期保护提供重要的理论基础,具有广泛的实际工程应用价值和应用前景。     

DEM investigation of weathered rocks using a novel bond contact model

The distinct element method(DEM) incorporated with a novel bond contact model was applied in this paper to shed light on the microscopic physical origin of macroscopic behaviors of weathered rock, and to achieve the changing laws of microscopic parameters from observed decaying properties of rocks during weathering. The changing laws of macroscopic mechanical properties of typical rocks were summarized based on the existing research achievements. Parametric simulations were then conducted to analyze the relationships between macroscopic and microscopic parameters, and to derive the changing laws of microscopic parameters for the DEM model. Equipped with the microscopic weathering laws, a series of DEM simulations of basic laboratory tests on weathered rock samples was performed in comparison with analytical solutions. The results reveal that the relationships between macroscopic and microscopic parameters of rocks against the weathering period can be successfully attained by parametric simulations. In addition, weathering has a significant impact on both stressestrain relationship and failure pattern of rocks.     

Influence of weathering on the engineering properties of Harsit granitic rocks (NE Turkey)

Weathering and hydrothermal alteration of the granitic rocks in the Eastern Black Sea Region (NE Turkey) are important phenomena affecting the engineering projects in the region. The study investigated the probable paths of rock-forming mineral transformations due to weathering in the Harsit granitoid rocks, the changes of the major oxides as a consequence of weathering and the effects of weathering on the engineering properties. To identify the changes in the major oxides, the volume concentrations were considered in relation to the dry density. Chemical leaching during weathering was shown to be significant in changing the minerals. It was concluded that the engineering properties of the weathered granitic rocks can be most reliably predicted by P-wave velocity.