Relationship between Texas Cone Penetrometer Tests and Axial Resistances of Drilled Shafts Socketed in Clay Shale and Limestone

Modern methods for designing drilled shafts in soft rock require knowledge of the compressive strength and modulus of the rock. However, rock jointing at many sites prohibits the recovery of samples of sufficient length and integrity to test rock cores in either unconfined or triaxial compression tests. Since rational design procedures usually require values of compressive strength, surrogate methods must be employed to estimate the compressive strength of the rock. The surrogate methods considered in this study was Texas cone penetrometer tests, and performed at several sites in North Central Texas. In order to develop the relationships between Texas cone penetrations and side and base resistances of rock socketed drilled shafts, three field load tests were conducted. Based on the field study and literature reviews, a relationship between Texas cone penetration tests and axial resistances of rock socketed drilled shafts was proposed.     

Self-Aeration and Friction over Rock Chutes in Uniform Flow Conditions

Interaction between the free surface and the bed material in flow over rock chutes under macroroughness conditions leads to a high air entrainment into the flow. The note reports on an experimental study about air diffusion features in the flow over a long rock chute. Air concentration profiles and water depths over a uniform bed material were measured. An empirical equation for the average air concentration in macroroughness condition for steep slopes is proposed. A new Darcy-Weisbach equivalent friction factor for long chutes as a function of the slope and the relative equivalent depth has also been found.     

岩石实验室反射光谱的相似系数聚类分析

以n维向量空间中的向量夹角为分类依据,对内蒙乌拉尔山地区53个岩石实验室反射光谱进行相似系数聚类分析,揭示出0.4～2.5μm岩石谱形的总体相似性差异。结果表明,岩石的电磁波属性不同于岩石学的分类属性,提出按谱形的相似性对岩石进行归类的方法及其意义。同时分析了成像光谱技术中光谱角度填图方法的优劣及改善措施,为成像光谱图像处理方法提供了十分有意义的光谱依据。     

Detection of features of a rupture structure in walls of an open pit in terms of the Muruntau open pit

In terms of the Muruntau open pit, the paper addresses the possibility of formation of a rupture structure in host rock, based on the analysis of its surface manifestations. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 80–89, January–February, 2008.     

EMR recording equipment for underground mines

The prototype of a new portable device of EMRR series (electromagnetic radiation recorder), EMRR-3 is developed and manufactured to monitor and forecast dynamic rock mass manifestations by electromagnetic radiation signals. The device makes it possible to predict dynamic manifestations based on algorithms of stable electromagnetic signal detection, to perform long-term (up to 8 h) digital recording of electromagnetic situation in underground mine workings, followed by the accumulated information computer-processing. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 2, pp. 115–122, March–April, 2008.     

告成煤矿井底水仓巷道变形原因及对策

通过对告成煤矿井底水仓巷道变形原因的分析，采用锚注方法对其进行注浆固化，提高了围岩的承载能力，改善了巷道的维护状况，为治理软岩巷道提拱了一条有效的途径。     

Estimation of radiation hazard indices from natural radioactivity of some rocks

1 Introduction Naturally occurring radionuclides 226Ra, 232Th and 40K are widespread in the earth’s environment and they exist in various geological formation such as soil, rock, water and plants [1]. These radionuclides pose exposure risks externally due to their γ-ray emissions and internally due to radon and its progeny, which emit alpha particles. Even though these radionuclides are widely distributed, their concentrations have been found to depend on the local geological condition and …     

Mass Angle of Repose of Open-Graded Rock Riprap

Mass angle of repose (that is, the angle at which a mass of sliding particles will come to rest) is a fundamental material property that is needed to design drainage channel linings composed of open-graded riprap stone, also called dumped rock riprap, which protect earthen slopes from erosion by flowing water. Multiple regression analysis of measurements at 74 stockpiles of dumped natural and crushed rock shows the angle to depend primarily on rock particle angularity and, to lesser extents, on the gradation and the median particle diameter of the stone mixture, the angle increasing with angularity, mixture nonuniformity, and particle size. Uncomplicated expressions are developed from the data to calculate the expected mass angle of repose of open-graded rock riprap along with prediction intervals.     

Soil and Rock Properties in a Young Volcanic Deposit on the Island of Hawaii

Deeply weathered lava flows of oceanic basalt reflect the mode and sequence of volcanic deposition, parent mineralogy, and postdepositional erosional and weathering processes. In turn, these are controlled by geology, geography, and climate. One particular site on the Island of Hawaii has been the focus of study to gain a better understanding of complex residual soil deposits, particularly in connection with a need to characterize seismic strong-motion propagation through decomposed surface soil and rock sequences. Materials at the site range from fully weathered volcanic soils, sometimes with unusual mineralogy and plasticity properties, to saprolite, weathered rock, vesicular basalt, and hard rock. Seismic surveys were conducted to investigate the distribution of these materials at the study site. Laboratory tests focused on saprolite and vesicular rock as two materials that are seldom reported on and that remain poorly characterized, at least with regard to conditions found in Hawaii.     

Physically Based Model for Evaluation of Rock Scour due to High-Velocity Jet Impact

Scour of rock may occur downstream of dam spillways, as a result of the impact of high-velocity jets. The phenomenon is traditionally assessed by means of (semi-) empirical methods. These partially neglect basic physical processes responsible for rock mass breakup. Therefore, a model to evaluate the ultimate depth and time evolution of scour in jointed rock is presented. The model is based on near-prototype scaled experimental investigations of transient water pressures in artificially created rock joints and on a numerical modeling of the measured pressures. It describes two different ways of rock mass destruction, i.e., failure by instantaneous or progressive breakup of closed-end rock joints, and failure by dynamic ejection of single rock blocks. The corresponding computational methods are easily applicable to practice, without neglecting relevant physics. The basic principles are outlined and applied to the well-known scour hole at Cabora-Bassa Dam.