scholarly journals Experimental Study on the Creep Characteristics of Coal Measures Sandstone under Seepage Action

Processes ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 110 ◽  
Author(s):  
Ziheng Sha ◽  
Hai Pu ◽  
Ming Li ◽  
Lili Cao ◽  
Ding Liu ◽  
...  
Keyword(s):  
Creep Deformation ◽  
Deformation Rate ◽  
Confining Pressure ◽  
Test System ◽  
Stability Control ◽  
Surrounding Rock ◽  
Natural State ◽  
Saturation State ◽  
Creep Characteristics ◽  
Coal Measures

The seepage action of underground water accelerates the deformation of roadway surrounding rock in deep mines. Therefore, the study of creep characteristics of surrounding rock under seepage action is the basis for the stability control of roadway surrounding rock in deep water-rich areas. In this paper, a seepage-creep coupling test system for complete rock samples was established. Combined with a scanning electron microscopy (SEM) test system, the seepage-creep law of coal measures sandstone and the damage mechanism were revealed. The study results showed that the maximum creep deformation of sandstone under natural and saturation state decreased gradually with the increase of confining pressure, and the maximum creep deformation under saturation state was greater than the corresponding value under natural state when the confining pressure was same. When the confining pressure was constant, the creep deformation, the constant creep deformation rate and the accelerated creep deformation rate of sandstone increased rapidly with the increase of infiltration pressure. With the change of time, the change of permeability parameters went through three cycles; each cycle was divided into two stages, slow change stage and rapid change stage, and the rate of variation increased with the increase of the seepage pressure. Based on the macroscopic and microscopic characteristics of sandstone rupture, the connection between macroscopic and microscopic mechanism on sandstone rupture was established. The results in this paper can provide a theoretical basis for stability control of roadway surrounding rock in water-rich areas.

Experimental Study and Numerical Simulation of Rock Mass Seepage Characteristics of Tunnel Engineering

2011 ◽  
Vol 243-249 ◽  
pp. 3538-3545
Author(s):  
Yong Dong Jiang ◽  
Ling Xiong ◽  
Xing Yang Yang ◽  
Quan Zhen ◽  
Zong Ling Yan
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Pore Pressure ◽  
Confining Pressure ◽  
Test System ◽  
Surrounding Rock ◽  
Simultaneous Action ◽  
Seepage Field ◽  
Variation Characteristics ◽  
Seepage Characteristics

In this research, the MTS815 rock mechanics test system , produced by American MTS co., has been conducted with transient method to study the seepage characteristics of rock under different confining pressure. Experiments have obtained the following results: with the confining pressure increased, penetration ability of water in rock decreased, but the start-up pressure gradient increased; permeability of rock decreased with the increase of effective confining pressure, which had negative exponent functional relationship between them. Based on previous researches, the study has established filtration equation which couples with stress field, temperature field and seepage field. Combined with the practical tunnel project, numerical simulated the variation characteristics of deformation of tunnel surrounding rock, pore pressure and seepage field under three fields non-coupling and coupling, numerical simulation obtained: the difference among deformation of surrounding rock, pore pressure and seepage field distribution under the coupling and non-coupling is remarkable, so it must consider the simultaneous action of fluid - solid - heat when we need to research the working of seepage law of groundwater in tunnel rock mass, and the research results enjoy important theoretical significance and practical application value.

scholarly journals A Time-Dependent Creep Constitutive Model of Deep Surrounding Rock Under Temperature-Stress Coupling

2021 ◽  
Author(s):  
Xiaofeng Li ◽  
Zhixiang Yin
Keyword(s):  
Creep Deformation ◽  
Least Squares Method ◽  
Variable Parameter ◽  
Creep Damage ◽  
Strain Ratio ◽  
Test System ◽  
Surrounding Rock ◽  
Creep Model ◽  
Accelerated Creep ◽  
Triaxial Creep Test

Abstract In order to study the creep behavior of surrounding rock of Hengda coal mine in Fuxin under different temperature, the triaxial creep test of sandstone is carried out by MTS815.02 test system. Based on the Nishihara model, the model creep parameters are denormalized by introducing the relationship among damage variables, time and temperature. The improved variable parameter creep aging model is obtained. The creep parameters are identified by least squares method. The correctness of the creep model is verified by comparing the experimental data with the model curves. The results show that the instantaneous strain to the total strain ratio decreases first and then increases due to the compaction deformation of the internal voids under the initial stress level. The decrease of temperature effectively increases the rock bearing capacity and delays the creep damage time. The established variable-time aging creep model can not only describe the rock attenuation creep and stable creep deformation characteristics, but also makes up for the shortcomings of the traditional creep model that can not describe the accelerated creep characteristics. And it predict the development law of creep deformation well. The model is in good agreement with the test curve, which shows the correctness and rationality of the model. It has guiding significance for actual engineering support and prediction of long-term deformation of surrounding rock.

scholarly journals A Time-Dependent Creep Constitutive Model of Deep Surrounding Rock under Temperature-Stress Coupling

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaofeng Li ◽  
Zhixiang Yin
Keyword(s):  
Creep Deformation ◽  
Test System ◽  
Surrounding Rock ◽  
Creep Model ◽  
Spring Element ◽  
Rock Creep ◽  
Accelerated Creep ◽  
Different Temperatures ◽  
Creep Constitutive Model ◽  
Triaxial Creep Test

In order to study the creep behavior of the surrounding rock of Hengda coal mine in Fuxin under different temperatures, the triaxial creep test of sandstone is carried out by the MTS815.02 test system. The relationship between damage variables and temperature is constructed based on the Weibull distribution of the meso-probability voxel intensity. Aiming at the nonlinear characteristics of rock creep, a nonlinear viscous pot element and a nonlinear spring element are proposed. The two linear viscous pot elements and one linear spring element in the Nishihara model can be replaced separately. Thus, an unsteady parameter creep model is established. The comparison between the Nishihara model curve and the model and the experimental curves in this article has been added to the article. Furthermore, the superiority of this model can be proved. The results show that the established variable-time aging creep model not only can describe the rock attenuation creep and stable creep deformation characteristics but also can make up for the shortcomings of the traditional creep model that cannot describe the accelerated creep characteristics. Moreover, it predicts the development law of creep deformation well. The model is in good agreement with the test curve, which shows the correctness and rationality of the model. It has guiding significance for actual engineering support and prediction of long-term deformation of surrounding rock.

Study on mechanical properties and damage evolution of carbonaceous shale under triaxial compression with acoustic emission

2021 ◽  
pp. 105678952199119
Author(s):  
Kai Yang ◽  
Qixiang Yan ◽  
Chuan Zhang ◽  
Wang Wu ◽  
Fei Wan
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Water Content ◽  
Damage Evolution ◽  
Damage Assessment ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Damage Variable ◽  
Natural State ◽  
Carbonaceous Shale

To explore the mechanical properties and damage evolution characteristics of carbonaceous shale with different confining pressures and water-bearing conditions, triaxial compression tests accompanied by simultaneous acoustic emission (AE) monitoring were conducted on carbonaceous shale rock specimens. The AE characteristics of carbonaceous shale were investigated, a damage assessment method based on Shannon entropy of AE was further proposed. The results suggest that the mechanical properties of carbonaceous shale intensify with increasing confining pressure and degrade with increasing water content. Moisture in rocks does not only weaken the cohesion but also reduce the internal friction angle of carbonaceous shale. It is observed that AE activities mainly occur in the post-peak stage and the strong AE activities of saturated carbonaceous shale specimens appear at a lower normalized stress level than that of natural-state specimens. The maximum AE counts and AE energy increase with water content while decrease with confining pressure. Both confining pressure and water content induce changes in the proportions of AE dominant frequency bands, but the changes caused by confining pressure are more significant than those caused by water content. The results also indicate that AE entropy can serve as an applicable index for rock damage assessment. The damage evolution process of carbonaceous shale can be divided into two main stages, including the stable damage development stage and the damage acceleration stage. The damage variable increases slowly accompanied by a few AE activities at the first stage, which is followed by a rapid growth along with intense acoustic emission activities at the damage acceleration stage. Moreover, there is a sharp rise in the damage evolution curve for the natural-state specimen at the damage acceleration stage, while the damage variable develops slowly for the saturated-state specimen.

scholarly journals Study of the Stability Control of the Rock Surrounding Double-Key Strata Recovery Roadways in Shallow Seams

2019 ◽  
Vol 2019 ◽  
pp. 1-21 ◽  
Author(s):  
Cheng Zhu ◽  
Yong Yuan ◽  
Zhongshun Chen ◽  
Zhiheng Liu ◽  
Chaofeng Yuan
Keyword(s):  
Engineering Application ◽  
Stability Control ◽  
Surrounding Rock ◽  
Control Effect ◽  
Pressure Relief ◽  
Support Design ◽  
Key Strata ◽  
Fracture Development ◽  
Surrounding Rock Control ◽  
The Stability

The stability control of the rock surrounding recovery roadways guarantees the safety of the extraction of equipment. Roof falling and support crushing are prone to occur in double-key strata (DKS) faces in shallow seams during the extraction of equipment. Therefore, this paper focuses on the stability control of the rock surrounding DKS recovery roadways by combining field observations, theoretical analysis, and numerical simulations. First, pressure relief technology, which can effectively release the accumulated rock pressure in the roof, is introduced according to the periodic weighting characteristics of DKS roofs. A reasonable application scope and the applicable conditions for pressure relief technology are given. Considering the influence of the eroded area on the roof structure, two roof mechanics models of DKS are established. The calculation results show that the yield load of the support in the eroded area is low. A scheme for strengthening the support with individual hydraulic props is proposed, and then, the support design of the recovery roadway is improved based on the time effects of fracture development. The width of the recovery roadway and supporting parameters is redesigned according to engineering experience. Finally, constitutive models of the support and compacted rock mass in the gob are developed with FLAC3D software to simulate the failure characteristics of the surrounding rock during pressure relief and equipment extraction. The surrounding rock control effects of two support designs and three extraction schemes are comprehensively evaluated. The results show that the surrounding rock control effect of Scheme 1, which combines improved support design and the bidirectional extraction of equipment, is the best. Engineering application results show that Scheme 1 realizes the safe extraction of equipment. The research results can provide a reference and experience for use in the stability control of rock surrounding recovery roadways in shallow seams.

scholarly journals Experimental Test on Nonuniform Deformation in the Tilted Strata of a Deep Coal Mine

2021 ◽  
Vol 13 (23) ◽  
pp. 13280
Author(s):  
Hai Wu ◽  
Qian Jia ◽  
Weijun Wang ◽  
Nong Zhong ◽  
Yiming Zhao
Keyword(s):  
High Stress ◽  
Stability Control ◽  
Surrounding Rock ◽  
Experimental Results ◽  
Lower Side ◽  
Reinforcement Scheme ◽  
Deformation And Failure ◽  
True Triaxial ◽  
Deep Mine ◽  
Deep Coal Mine

Taking a deep-mine horizontal roadway in inclined strata as our research object, the true triaxial simulation technique was used to establish a model of the inclined strata and carry out high-stress triaxial loading experiments. The experimental results show that the deformation of surrounding rock in the roadway presents heterogeneous deformation characteristics in time and space: the deformation of the surrounding rock at different positions of the roadway occurs at different times. In the process of deformation of the surrounding rock, deformation and failure occur at the floor of the roadway first, followed by the lower shoulder-angle of the roadway, and finally the rest of the roadway. The deformation amount in the various areas is different. The floor heave deformation of the roadway floor is the greatest and shows obvious left-right asymmetry. The deformation of the higher side is greater than that of the lower side. The model disassembly shows that the development of cracks in the surrounding rock is characterized by more cracks on the higher side and fewer cracks on the lower side but shows larger cracks across the width. The experimental results of high-stress deformation of the surrounding rock are helpful in the design of supports, the reinforcement scheme, and the parameter optimization of roadways in high-stress-inclined rock, and to improve the stability control of deep high-stress roadways.

Analysis of Creep Characteristics of Shallow Mined-Out Areas Roof under Low Stress Conditions

2011 ◽  
Vol 105-107 ◽  
pp. 832-836 ◽  
Author(s):  
Shu Ren Wang ◽  
Hui Hui Jia
Keyword(s):  
Creep Deformation ◽  
Thick Plate ◽  
Plate Theory ◽  
Technical Problem ◽  
Stress Conditions ◽  
Creep Model ◽  
Term Strength ◽  
Creep Characteristics ◽  
Over Time

Under low stress conditions, when the load exerting on the mined-out areas roof is less than the rock long-term strength, the rock roof will generate some creep deformation. In order to prevent the roof of the mined-out areas suddenly collapse, and to ensure the operator and construction equipment above the mined-out areas safety, it is an important security technical problem to reveal the creep characteristics of the shallow mined-out areas roof. Taking the mined-out areas of Antaibao Surface Mine as background, considering the rheological properties of rock roof, and assuming the roof was a rectangular thick plate, the creep characteristics of mined-out areas roof were analysed by applying the thick plate theory and Kelvin creep model. The regression equation of the roof deflection increment over time was given, and the creep characteristics of the shallow mined-out areas roof were revealed also.

Creep Characteristics Analysis of Oil Shale and its Application

2010 ◽  
Vol 29-32 ◽  
pp. 2614-2619 ◽  
Author(s):  
Jun Guang Wang ◽  
Bing Liang
Keyword(s):  
Oil Shale ◽  
Stability Control ◽  
Creep Model ◽  
Test Results ◽  
Creep Properties ◽  
Creep Stage ◽  
Creep Characteristics ◽  
Roadway Stability ◽  
Theoretical Significance ◽  
Characteristics Analysis

to study oil shale creep properties, we use rock SJ-1B three-axis creep instrument on oil shale to carry three axis creep test. Through test results, the creep of oil shale is nonlinear, and in accelerating creep stage oil shale injury increased dramatically. Using Burgers creep model introduced damage variable to analyse the oil shale surrounding stress and displacement field and Systematically analyse the creep properties under various support intensity. So it has important theoretical significance and value for the oil shale resource development and roadway stability control.

The Vehicles ESP Test System Based on Active Braking Control

2012 ◽  
Vol 588-589 ◽  
pp. 1552-1559
Author(s):  
Lu Zhang ◽  
Guo Ye Wang ◽  
Guo Yan Chen ◽  
Zhong Fu Zhang
Keyword(s):  
Control System ◽  
Test System ◽  
Stability Control ◽  
Control Test ◽  
Control Performance ◽  
Vehicle System ◽  
Braking Control ◽  
Set Up ◽  
The Stability ◽  
Driving Stability

This paper proposes an active braking control dynamical system in order to establish a safe and efficient vehicle driving stability control test system. Aiming at Chery A3 sedan, set up the active braking control dynamic simulation system base on MATLAB/Simulink. Adopting the brake driving integration ESP control strategy, analyze and verify the stability control performance of independent vehicle system and vehicle ESP test system based on active braking control respectively in under steering and excessive steering two test conditions. The analyzing results indicate that the test system based on active braking control can effectively assist vehicle travelling in the absence of ESP control or ESP control system failure; when vehicle has ESP control system, the driving stability control performance of this system and independent vehicle system has remarkable consistency. The active braking control system provides a basis for research of vehicle driving stability control test.

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