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911.
912.
Yozo Kudo Osam Sano Naokuni Murashige Yoshiaki Mizuta Koji Nakagawa 《Pure and Applied Geophysics》1992,138(4):641-656
The double-torsion test using Aji granite was carried out to investigate the interaction between stress-induced crack path and mineral grains. Crack velocities were controlled at range 10–7 m/s to 10–1 m/s. After the stressed specimens were dyed, we checked the crack path by thin section analysis, using an optical microscope. The stress-induced crack path was divided into two types, transgranular and intergranular cracks, and each path was subdivided with respect to mineral grains. In spite of the extensive range of crack velocities, the ratios between the transgranular and intergranular crack lengths did not change. The crack paths were all jagged, and often showed detour around the grain boundary when faced with obstacles like hard grains or preexisting cracks. That is to say, quartz grain played an important role as an obstacle. Feldspar grain could change the crack path because of its cleavage plane. Biolite grain had a serious effect on the path even if its constitution ratio is very small. Fractal dimensions of the crack paths were calculated by three methods, as indicators of surface roughness. The fractal dimensions were shown in a slight trend with the change of crack velocity. This trend can be explained from the point of limited cracking rate in stress corrosion. 相似文献
913.
Paul C. Augustinus 《地球表面变化过程与地形》1992,17(1):39-51
The erosional morphology in the vicinity of the Main Divide of the Southern Alps, and Fiordland, New Zealand, appears to be a product of the interaction between Alpine Fault-induced tectonic processes, rock mass strength of the uplifted and eroded bedrock, and the processes acting to denude the developing mountain landscape. The magnitude of the effects of glacial erosion on the landscape is directly controlled by the size and physical properties of the glaciers, whilst the form of the trough is a direct consequence of the rock mass strength (RMS) properties of the slope rock. Realistic models of development of the cross-profile shape of glacial valleys must take into consideration the RMS properties of the eroded substrate. 相似文献
914.
本文以水口山、宝山、锡矿山、洪水坪、湘潭锰矿等各矿区的实际资料为依据,从影响矿坑涌水量计算的诸因素中,提出了矿坑涌水量全年中出现次数最多的值作为涌水量的基准值的概念,并以此值大小把矿坑涌水量分为3大类7亚类;对涌水量的动态变化采用涌水量最大值与正常值之比作为不稳定系数来表达,并将其分为4类;据动静储量的比例系数值把矿坑水储量分为静型、静动型和动型3类,从而确定了涌水量计算的内容,对计算精度依照基准值分类各划分了四个等级和相对应的储量等级,同时确定了相应的误差值与评分标准。 相似文献
915.
916.
917.
The failure of a slope in a phosphate mine by shear-sliding along a clay-filled bedding plane in limestone, and by separation across a tension crack at the back, is back-analysed. The failure cannot be explained using laboratory measured values of the shear strength parameters. In order to simulate field conditions better two physical models of the bedding plane were prepared for testing under triaxial compression. Cylindrical cores with an inclined saw-cut discontinuity were filled with remoulded montmorillonite. It is shown that failure in the models initiates along the contacts between the clay infilling and the limestone boundaries, and not through the clay itself, as would be intuitively expected. Furthermore, it is argued that in the analysis of rock slope stability in general, and particularly in the case of clay-filled discontinuities, the influence of paleo-overburden stress on frictional resistance must be resolved before the appropriate constitutive law can be established for analysis. 相似文献
918.
When rock failure is unavoidable, the designer of engineering structures must know and account for the residual strength of the rock mass. This is particularly relevant in underground coal mine openings. Pre-existing discontinuities play an important role in the mechanical behavior of rock masses and thus it is important to understand the effects of such pre-existing discontinuities on the residual strength. For this purpose, the present study demonstrates a numerical analysis using a discrete element method simulation. The numerical results indicate that fracture intensity has no significant influence on the residual strength of jointed rock masses, independent of confining conditions. As confining pressures increase, both peak and residual strengths increase, with residual strength increasing at a faster rate. The finding was further demonstrated by analyzing documented laboratory compressive test data from a variety of rocks along with field data from coal pillars. A comprehensive interpretation of the finding was conducted using a cohesion-weakening-friction-strengthening (CWFS) model. The effect of rock bolts on rock mass strength was also evaluated by using a discrete element method model which suggested that rock bolts can significantly increases residual strength but have limited effect on increasing the peak strength of rock masses. 相似文献
919.
Daniela Porcino Vito Nicola Ghionna Raffaella Granata Vincenzo Marcianò 《Geomechanics and Geoengineering》2016,11(2):164-175
The purpose of this paper is to investigate mechanical and hydraulic properties of sands treated with mineral-based grouts through the results of a laboratory test programme consisting of unconfined compression tests (UCS), triaxial bender element tests (BeT) and constant flow permeability tests in triaxial apparatus. An improved apparatus was set up for obtaining high quality, multiple grouted specimens from a single column. Two selected natural sands having different grain sizes were grouted with two mineral-based silica grouts, resulting in different levels of improvement. The behaviour of the sands treated by mineral grouts, in terms of strength, initial stiffness and permeability, was compared with that exhibited by more traditional silicate grouts. The results of this study indicate that sands treated with mineral grouts result in higher strengths, higher initial shear modulus and lower permeability values than the sands treated with the silicate solution. The effect of grout type, effective confining pressure, and sand particle-size on small-strain shear modulus of grouted sand specimens was evaluated. Based on test results, the small strain shear modulus increment from treated to untreated specimens has been correlated with the unconfined compressive strength, obtaining a unique relationship regardless of grout type and grain-size of tested sands. 相似文献
920.
曹四夭钼矿床是目前全国发现并探明的10个超大型钼矿床中唯一以太古宙基底作为赋矿围岩的矿床。太古宇及其岩性为集宁岩群黄土窑岩组浅粒岩和变粒岩;岩石饱和抗压强度10.56~106.02 MPa,属软弱-坚硬岩类;其利于开采而不利于支护。岩、矿体整体属中等-稳定岩体,局部岩体稳定性差,工程地质勘查类型为第三类第一型。在未来矿山开采过程中应注意局部的软弱夹层,尤其是在构造破碎带或碎裂岩石区等地段实施坑道作业易发生矿山工程地质问题,应加强支护;其余岩段稳固性能尚属良好。 相似文献