Papers by Keyword: Granite

Abstract: The physical processes triggering the fluid flow within the stressed rock are highly complex and not fully understood. The granite sample obtained from Creighton mine, Canada, was subjected to the temperature-pressure effects using a special rock mechanic testing machine equipped with a high precision gas monitor. It is shown that when the sample approached to the peak stress during the uniaxial compression test, the connective cracks instantaneously occurred accompanied by a swarm of AE activities, which suddenly decrease the fluid pore pressure. This change can be able to drive the gas back to the newly emerging crack due to the formation of gas pressure gradient within the damage zones. It is indicated that the different permeabilities among the zones can dominate the suction-exhaust proceeding of pore fluids within rock mass. Beyond the volumetric strain at null, the deformation of the stressed rock leads to a reversely change in pore pressure of closed pores. The feature for the gas emission determined by the changes in pore structure of rock is also discussed and analyzed.

Abstract: This paper makes the acoustic emission of granite under uniaxial compression and splitting tensile test by electro-hydraulic testing machine and AE .We studied the relationship of uniaxial compressive strength and splitting tensile strength with the loading rate and AE characteristics of granite .The results show that uniaxial compressive strength and peak strain raise with loading rate, the AE energy gradually increases and get maximum in the 30% of the peak stress in the process of uniaxial compression test, and in the splitting tensile AE energy generates in the initial loading and gets maximum when the granite brittle fracture.

Abstract: Experiments on granite under uniaxial compression at high temperature of 25~850°C and after high temperature of 25~1300°C were conducted to study the effect of temperature on rock strength and deformation quality. The results show that: (1) Fitting curves between temperature strain and thermal expansion coefficient with temperature are closely first order growth exponential function relation at high temperature. Temperature strain has mutagenicity after high temperature, which can not reflect rock deformation law at high temperature exactly. (2)Mechanical properties of granite weak continuously at high temperature. Compressive strength and elastic modulus show second order attenuation trend of exponential law. But mechanical properties show mutation state after high temperature, which is closely related to the alteration of rock crystal form and brittle-ductile transition. Regression curves between compressive strength and elastic modulus with temperature are closely polynomial curve. The results reflect the fundamental regulation of granite’s interior structure changing under the action of different temperature, which will provide some reference value to rock engineering involved in high temperature.

Abstract: This work presents 3-D Finite Element Model of the heat transfer inside granite during pulsed laser ablation with the aim of achieving laser cleaning treatment without damaging the stone surface. The model is focused on biotite, the most affected granite-forming mineral, owing to its low melting temperature. The model predicts sizes of the molten region that are consistent with experimental results. Moreover, the effects of different irradiation parameters; i.e., fluence, laser repetition frequency, and speed of scan have been investigated through the size of the biotite molten region. This model may be considered as the first stage of a comprehensive model of the laser ablation process in granite.

Abstract: Time-dependent brittle deformation is a foundational process operating in the underground engineering. So, the study of its characterization is essential to the design and construction of excavations in the rocks for high level radioactive waste disposal repositories. In this study, three constant stress tests under different confining pressures were performed on specimens of Beishan granite. Based on the laboratory results, we investigated mechanical creep behavior of Beishan granite under low confining pressures and compared the results with previous investigations.

Abstract: In order to study the relationship between the design parameters of the shield machine and the strength of rock, the behaviours of rocks under the conventional triaxial compression, the complete stress-strain curves under different confining pressures of three typical rocks, i.e. granite, limestone and red sandstone, were taken out for analysis. From the curves, the values of elastic modulus E and Poisson's ratio μ were gained and the relationships between the following parameters were figured out, which are peak strength versus confining pressure, residual strength versus confining pressure, strain at peak strength versus confining pressure, and strain at residual strength versus confining pressure. According to the values and relationships, the complete stress-strain curves were divided into three parts. For each part, a constitutive equation was established by using the strain softening trilinear elastic-brittle-plastic constitutive model, and all the related parameters in the constitutive equations were also presented, which provide a theoretical foundation for the digital design of the cutter head and cutters of Shield machine.

Abstract: Bitumen pavement suffers from moisture damage mainly due to loss of durability and stability in a short span of service life. Filler is known to be capable of increasing the stiffness of bitumen binder, contributing to improvement of moisture sensitivity of bitumen mixture. In this paper a new type of filler named 'Compound Fly Ash Modifier' (CFAM) was introduced in order to enhance the bond strength between acidic aggregate with bitumen. The primary object is to determine the effect of CFAM on the moisture sensitivity of bitumen mixtures prepared by gneiss and granite respectively, which are termed acidic aggregate. Modified Lottman test and fatigue test were conducted. The results show that CFAM improves the resistance of mixes to moisture damage in the increase in indirect tensile strength and the extension of fatigue life. Finally the mechanism of modified effects for CFAM is discussed.

Abstract: The rock mass structure of granite is massive, so the stability of granite slope is good. Massive rock become stratoid structure when the rock mass contain discontinuities such as joints and faults. The deformation and destruction of the slope rock mass is controlled by the behaviour and orientation of the discontinuities. Especially, the over-dip discontinuities controlled the slope stability. In this paper, based on the abundant field investigation on the slope in left bank diversion tunnel inlets of Nuozadu power station in Lancang River, the types of rock mass structures and the combination between structural planes and slope surface are studied in detail so as to analyze the slope deformation mechanism. Finally, the slope stability is researched systematically by limit equilibrium method and FLAC numerical simulation analysis. A set of technical and methodological system on stability research of over-dip stratoid structure rock slope will hoped to be established.

Abstract: The granite is widely used for city architectural decoration, outdoor sculpture. Study on granite reflection is important for artificial building recognition and rock or mineral exploration. The Bidirectional Reflectance Distribution Function (BRDF) is used in conventional remote sensing to characterize the geometrical scatter of materials. Polarization occurs with multi-angle scatter. 90°and 0°polarized bidirectional reflection along the waveband of 300~2500nm for various view azimuth and zenith angles on polished granite are acquired. DOP then is calculated.

Abstract: In this paper, the shear strength of different structural planes are tested with the hand portable shear tester in site. The study shows that the shear strength of the structural plane in the granite mass is mainly related to the roughness, the degree of cementation and interlocking of the structural plane. The shear strength of the smooth plane is less, and the plane with interlock partly is larger. In the tests basis, the paper posts out the relation between τ and σ, which can be used to calculate the stability of the landslide。