scholarly journals Alteration in Material Properties of an Intact Rock due to Drilling and Bolting Operations

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Lok Priya Srivastava ◽  
Mahendra Singh
Keyword(s):  
Rock Mass ◽  
Uniaxial Compression ◽  
Material Properties ◽  
Substantial Effect ◽  
Rock Material ◽  
Intact Rock ◽  
Simple Problem ◽  
Rock Bolts ◽  
Natural Rock ◽  
Physical Tests

Rock material properties play an important role in assessing rock mass behaviour. Passive rock bolts stabilize a rock mass by restricting relative displacements; however, they may reduce rock material properties. While assessing properties of rock mass reinforced by rock bolts, the alteration caused in rock material properties due to drilling and bolting operation should be well understood. The present work makes an attempt to study the alteration in rock material properties due to drilling and bolting operations. The study has been conducted through physical tests on natural rock specimens in the laboratory. Virgin cylindrical specimens of intact rock were tested under uniaxial compression. Drilling was done through specimens and fully grouted bolts were installed. These specimens were also tested under uniaxial compression. It is observed that the drilling has substantial effect on the uniaxial compressive strength and modulus. A simple problem of tunnel is analysed which demonstrates the effect of alteration in material properties on the strength of rock mass around the tunnel in the field condition.

A Review of Soft Computing Methods Application in Rock Mechanic Engineering

2016 ◽  
pp. 1-70 ◽  
Author(s):  
Nurcihan Ceryan
Keyword(s):  
Rock Mass ◽  
Soft Computing ◽  
Rock Mechanics ◽  
Computing Methods ◽  
Rock Material ◽  
Rock Slope Stability ◽  
Rock Mechanic ◽  
Natural Rock ◽  
Soft Computing Techniques ◽  
Soft Computing Methods

Engineering behavior of rock mass is controlled by many factors, related to its nature and the environmental conditions. Determining all the parameters, ranking their weights, and clarifying their relative effects are very difficult tasks to accomplish. To overcome these difficulties, many researchers have employed soft computing methods in rock mechanics engineering. The soft computing methods have taken an important role in rock mechanics, and their abilities to address uncertainties, insufficient information and ambiguous linguistic expressions stand out in treating complex natural rock mass. This chapter briefly will review the development of soft computing techniques in rock mechanics engineering, especially in predicting of rock engineering classification system and mechanical properties of rock material and rock mass, determination weathering degree of rock material, evolution of rock performance, blasting and, rock slope stability. In addition, the future of the development and application of soft computing in rock mechanics engineering is discussed.

scholarly journals Application of Neural Networks for the Reliability Design of a Tunnel in Karst Rock Mass

2020 ◽  
Author(s):  
Meho Saša Kovačević ◽  
Mario Bačić ◽  
Kenneth Gavin
Keyword(s):  
Neural Network ◽  
Rock Mass ◽  
Uniaxial Compression ◽  
Reliability Index ◽  
Reliability Assessment ◽  
Probability Of Failure ◽  
Intact Rock ◽  
Design Parameters ◽  
Tunnel Design ◽  
Assessment Techniques

This paper offers a solution to overcome time-consuming numerical analysis for the evaluation of the impact of tunnel construction in a complex karst environment by implementing Monte-Carlo simulation (MCS) using a neural network (NN) tool. The rock mass is described using three parameters, Geological Strength Index, the uniaxial compression strength of the intact rock and the Hoek-Brown parameter for the intact rock mi. By using their probabilistic distribution as an input, a developed neural network NetTUNN produces probabilistic distributions of tunnel crown displacement, rock bolt axial load and shotcrete uniaxial compression stress. A full MCS is then applied on these NetTUNN outputs to determine the reliability index and probability of failure for the relevant limit states. To demonstrate the potential of NN in tunnel design, a case study tunnel Pećine in Croatia is used, where the NetTUNN-assisted MCS assessment served as a benchmark to evaluate approximate reliability assessment techniques. It was shown that the developed NN can be used as an accurate surrogate model for determination of probabilistic distributions of tunnel design parameters. Further, it was shown that approximate reliability assessment techniques generally overestimate the reliability index and underestimate the probability of failure when compared to the NetTUNN assisted MCS.

scholarly journals A Review of Soft Computing Methods Application in Rock Mechanic Engineering

2016 ◽  
pp. 606-673
Author(s):  
Nurcihan Ceryan
Keyword(s):  
Rock Mass ◽  
Soft Computing ◽  
Rock Mechanics ◽  
Computing Methods ◽  
Rock Material ◽  
Rock Slope Stability ◽  
Rock Mechanic ◽  
Natural Rock ◽  
Soft Computing Techniques ◽  
Soft Computing Methods

Engineering behavior of rock mass is controlled by many factors, related to its nature and the environmental conditions. Determining all the parameters, ranking their weights, and clarifying their relative effects are very difficult tasks to accomplish. To overcome these difficulties, many researchers have employed soft computing methods in rock mechanics engineering. The soft computing methods have taken an important role in rock mechanics, and their abilities to address uncertainties, insufficient information and ambiguous linguistic expressions stand out in treating complex natural rock mass. This chapter briefly will review the development of soft computing techniques in rock mechanics engineering, especially in predicting of rock engineering classification system and mechanical properties of rock material and rock mass, determination weathering degree of rock material, evolution of rock performance, blasting and, rock slope stability. In addition, the future of the development and application of soft computing in rock mechanics engineering is discussed.

scholarly journals Determination of Mechanical Properties of Altered Dacite by Laboratory Methods

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 813
Author(s):  
Veljko Rupar ◽  
Vladimir Čebašek ◽  
Vladimir Milisavljević ◽  
Dejan Stevanović ◽  
Nikola Živanović
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Rock Mass ◽  
Uniaxial Compressive Strength ◽  
Rock Material ◽  
Strength Parameter ◽  
Gradual Transition ◽  
Strength Parameters ◽  
Triaxial Compressive Strength ◽  
Heterogeneous Rock

This paper presents a methodology for determining the uniaxial and triaxial compressive strength of heterogeneous material composed of dacite (D) and altered dacite (AD). A zone of gradual transition from altered dacite to dacite was observed in the rock mass. The mechanical properties of the rock material in that zone were determined by laboratory tests of composite samples that consisted of rock material discs. However, the functional dependence on the strength parameter alteration of the rock material (UCS, intact UCS of the rock material, and mi) with an increase in the participation of “weaker” rock material was determined based on the test results of uniaxial and triaxial compressive strength. The participation of altered dacite directly affects the mode and mechanism of failure during testing. Uniaxial compressive strength (σciUCS) and intact uniaxial compressive strength (σciTX) decrease exponentially with increased AD volumetric participation. The critical ratio at which the uniaxial compressive strength of the composite sample equals the strength of the uniform AD sample was at a percentage of 30% AD. Comparison of the obtained exponential equation with practical suggestions shows a good correspondence. The suggested methodology for determining heterogeneous rock mass strength parameters allows us to determine the influence of rock material heterogeneity on the values σciUCS, σciTX, and constant mi. Obtained σciTX and constant mi dependences define more reliable rock material strength parameter values, which can be used, along with rock mass classification systems, as a basis for assessing rock mass parameters. Therefore, it is possible to predict the strength parameters of the heterogeneous rock mass at the transition of hard (D) and weak rock (AD) based on all calculated strength parameters for different participation of AD.

Simulation of Uniaxial Compression for Flexible Fibers of Wheat Straw Using the Discrete Element Method

2021 ◽  
Vol 64 (6) ◽  
pp. 2025-2034
Author(s):  
Matthew W Schramm ◽  
Mehari Z. Tekeste ◽  
Brian L Steward
Keyword(s):  
Discrete Element Method ◽  
Wheat Straw ◽  
Young’S Modulus ◽  
Uniaxial Compression ◽  
Material Properties ◽  
Young's Modulus ◽  
Discrete Element ◽  
Flexible Fibers ◽  
Dem Model ◽  
Element Method

HighlightsSimulation of uniaxial compression was performed with flexible fibers modeled in DEM.Bond-specific DEM parameters were found to be sensitive in uniaxial compression.A calibration technique that is not plunger-dependent is shown and validated.Abstract. To accurately simulate a discrete element method (DEM) model, the material properties must be calibrated to reproduce bulk material behavior. In this study, a method was developed to calibrate DEM parameters for bulk fibrous materials using uniaxial compression. Wheat straw was cut to 100.2 mm lengths. A 227 mm diameter cylindrical container was loosely filled with the cut straw. The material was pre-compressed to 1 kPa. A plunger (50, 150, or 225 mm diameter) was then lowered onto the compressed straw at a rate of 15 mm s-1. This experimental procedure was simulated using a DEM model for different material properties to generate a simulated design of experiment (DOE). The simulated plunger had a travel rate of 40 mm s-1. The contact Young’s modulus, bond Young’s modulus, and particle-to-particle friction DEM parameters were found to be statistically significant in the prediction of normal forces on the plunger in the uniaxial compression test. The DEM calibration procedure was used to approximate the mean laboratory results of wheat straw compression with root mean square (RMS) percent errors of 3.77%, 3.02%, and 13.90% for the 50, 150, and 225 mm plungers, respectively. Keywords: Calibration, DEM, DOE, Flexible DEM particle, Uniaxial compression, Wheat straw.

scholarly journals Self-potential response characteristics of red sandstone samples under uniaxial compression

2019 ◽  
Vol 16 (4) ◽  
pp. 742-752
Author(s):  
Cai Yang ◽  
Shengdong Liu ◽  
Haiping Yang
Keyword(s):  
Rock Mass ◽  
Uniaxial Compression ◽  
Inflection Point ◽  
Radial Direction ◽  
The Self ◽  
Potential Difference ◽  
Potential Response ◽  
Red Sandstone ◽  
Response Characteristics ◽  
Self Potential

Abstract Deformation and rupture of rock mass under loading cause the variation of electric potential. Response characteristics of self-potential and stress during the complete stress-strain process of red sandstones play an important role in evaluating the stress state of sandstone on the basis of self-potential. Experimental results demonstrate that the stress of red sandstone under uniaxial compression is linearly correlated with the self-potential difference before the first inflection point in the initial stage of loading. The average variation rate of self-potential difference and stress is 0.1325 mV MPa−1. As the loading pressure gradually increases and enters the softening stage (before the maximum loading point), the catastrophic points of uniaxial loading stress correspond to the inflection point of self-potential. The self-potential of red sandstone varies in a range of 0–45.6 mV in that case and it fluctuates most significantly around the maximum loading point, with a range of 0.3–195.5 mV. In the end stage of loading, the macroscopic rupture of the red sandstone sample is complete, the self-potential of red sandstone fluctuates slightly around the maximum load point and then gradually stabilizes. Moreover, it is found that self-potentials change more significantly in the radial direction than in the axial direction in the uniaxial compression experiment, indicating that self-potentials generated by rock mass rupture are more sensitive in the radial direction. The rupture process of red sandstone can be dynamically represented by the tempo-spatial evolution profiles of self-potential.

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