scholarly journals Influence of Moisture Content on the Structural Characteristics of Argillaceous Weakly Consolidated Rock Caused by Dynamic Loading in the Coal Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Lingdong Meng ◽  
Lijun Han ◽  
Hexuan Zhu ◽  
Wenlong Dong ◽  
Wei Li
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Structural Characteristics ◽  
Soft Rock ◽  
Uniaxial Compression Test ◽  
Hopkinson Pressure Bar ◽  
Dynamic Impact ◽  
Porosity Variation ◽  
Bar Test ◽  
Pressure Bar

The argillaceous weakly consolidated rock is a kind of soft rock that will bring great difficulties in the construction process. Specimens of such rock under different moisture contents are taken as the research object. By the Hopkinson pressure bar test (SHPB), the structural and mechanical characteristics of the rock under dynamic impact are analysed. With increasing moisture content, the transmitted wave amplitude decreases gradually, which indicates that the higher the moisture content of the rock is, the easier it is to deform under dynamic impact and the greater its plasticity. The boundary between plastic failure and brittle failure is 10% moisture content. Through a mercury injection test, the porosity variation is analysed. The porosity of the rock decreases with increasing moisture content after the same dynamic impact. The porosity curve can be roughly divided into two sections with a moisture content of 15% as the boundary. Based on a uniaxial compression test, the elastic modulus, peak strength, and residual strength of specimens after dynamic impact are analysed, and the mechanical properties of the rock are revealed. Its mechanical properties can be divided into three sections with a moisture content of 9.18% and 15.19%, and each section has obvious differences.

Dynamic compressive properties obtained from a split Hopkinson pressure bar test of Boryeong shale

2016 ◽  
Vol 22 (5) ◽  
pp. 764-770 ◽  
Author(s):  
Minju Kang ◽  
Jung-Woo Cho ◽  
Yang Gon Kim ◽  
Jaeyeong Park ◽  
Myeong-Sik Jeong ◽  
...  
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Hopkinson Pressure Bar ◽  
Compressive Properties ◽  
Split Hopkinson ◽  
Bar Test ◽  
Pressure Bar

Determination of mechanical properties from sharp dynamic indentation

2021 ◽  
pp. 030932472110592
Author(s):  
Bowen Si ◽  
Zhiqiang Li ◽  
Gesheng Xiao ◽  
Xuefeng Shu
Keyword(s):  
Mechanical Properties ◽  
Power Law ◽  
Split Hopkinson Pressure Bar ◽  
Indentation Test ◽  
Hopkinson Pressure Bar ◽  
Dynamic Indentation ◽  
Material Parameters ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Indentation Response

In this study, a dynamic indentation test method based on the split Hopkinson pressure bar is proposed to obtain the dynamic parameters of Ludwik power law constitutive, namely, Young’s modulus E, strength coefficient K, and strain hardening index n by analyzing dynamic indentation load-indentation depth curve obtained from the theories relating to the Hopkinson pressure bar. The important parameters, namely, loading curvature C and transformation factor [Formula: see text], are invoked to examine the dynamic indentation response results in a wide range of target material parameters. Finite element calculation results are processed through simulation of dynamic indentation response with broad material parameters. Furthermore, the analytical method is used to fit simulation results to obtain the analytical equations for elastic–plastic parameters and curvature parameters for the subsequent analysis. The analytical equation of forward model to predict dynamic indentation response parameter–loading curvature C of a known material is proposed. Then, the elastic–plastic parameters of unknown materials (according to Ludwik power law) are obtained by substituting the dynamic indentation response parameters into an inverse analytical equation under the two types of half-cone angle indenters. The method is verified by other typical materials, which shows that the dynamic indentation test based on the split Hopkinson pressure bar can obtain sufficient conditions to obtain dynamic mechanical properties of target materials.

The Effects of Water Saturation on Dynamic Mechanical Properties in Red and Buff Sandstones Having Different Porosities Studied with Split Hopkinson Pressure Bar (SHPB)

2015 ◽  
Vol 752-753 ◽  
pp. 784-789 ◽  
Author(s):  
Eun Hye Kim ◽  
Davi Bastos Martins de Oliveira
Keyword(s):  
Mechanical Properties ◽  
Dynamic Loading ◽  
Oil And Gas ◽  
Split Hopkinson Pressure Bar ◽  
Water Saturation ◽  
Dynamic Mechanical Properties ◽  
Hopkinson Pressure Bar ◽  
Dynamic Mechanical ◽  
Split Hopkinson ◽  
Pressure Bar

Dynamic mechanical behavior of geomaterials has been widely observed in tunneling, oil and gas extraction, and blasting in civil and mining applications. It is important to understand how much energy is necessary to break or fail geomaterials to optimize the design of blasting patterns, oil and gas extractions, demolition, military defense, etc. However, there is little understanding for quantifying the required energy to break geomaterials under dynamic loading. More importantly, as typical geomaterials tend to hydrate, it is necessary to understand how much energy will be needed to break the structures under water saturation. Thus, in this study, we analyzed the consumed energy used to deform geomaterials using a split Hopkinson pressure bar (SHPB), enabling to measure stress and strain responses of geomaterials under dynamic loading condition of high strain rate (102–104/sec). Two different saturation levels (dry vs. fully saturation) in two sandstone samples having different pore sizes were tested under dynamic loading conditions. Our results demonstrate that dynamic mechanical strength (maximum stress) is greater in the dry geomaterials when compared with the saturated samples, and Young’s modulus (or maximum strain) can be a useful parameter to examine porosity effects between dry and saturated geomaterials on dynamic mechanical properties.

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