Stability Analysis of Slope Considering the Energy Evolution of Locked Segment

2021 ◽  
Author(s):  
Xiangjie Yin ◽  
Hang Lin ◽  
Yifan Chen ◽  
Yi Tang ◽  
Yixian Wang ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Strain Energy ◽  
Slip Surface ◽  
Numerical Models ◽  
Progressive Failure ◽  
Failure Process ◽  
Elastic Strain Energy ◽  
Energy Evolution ◽  
Reduction Coefficient ◽  
The Relationship

Abstract Researches on the energy evolution of the key blocks is helpful to reveal the failure process of locked-segment type slope, whose stability is governed by the locking section along the potential slip surface. In order to study the failure mechanism of the locked segment in the process of slope progressive failure due to strength attenuation, a series of stability analysis on the numerical models of locked-segment type slope were implemented to record the relationship curve between energy and strength reduction coefficient. Then, according to the variation law and characteristic of energy evolution, the failure process of the locked segment was divided into four stages: elastic stage, initial damage stage, extensive damage stage and failure stage. And the reduction coefficient corresponding to the peak of the energy evolution curve was employed to achieve landslide warning. In addition, the method to determine the safety factor of locked-segment type slope was given, and its reliability was verified by comparing with other traditional methods. Finally, the formula for calculating the initial sliding velocity was presented based on the residual strain energy which is defined as the elastic strain energy of the locked segment when the slope is unstable.

scholarly journals An investigation on the effect of high energy storage anchor on surrounding rock conditions

2020 ◽  
Vol 7 (10) ◽  
pp. 201105
Author(s):  
Bowen Wu ◽  
Xiangyu Wang ◽  
Jianbiao Bai ◽  
Wenda Wu ◽  
Ningkang Meng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Energy Storage ◽  
Elastic Strain ◽  
Strain Energy ◽  
Hard Rock ◽  
Elastic Strain Energy ◽  
High Energy ◽  
Energy Evolution ◽  
Rock Bolts ◽  
High Energy Storage

High pre-tension bolt is an effective strata control technique and is the key to ensure the stability of anchorage and roadway. Based on the performances of high energy storage tension rock bolts in different rock properties, this study proposed a constitutive model to describe the energy balance of anchor under uniaxial compression. UDEC was used to simulate the behaviour of anchor in coal under uniaxial compression and the results were analysed to study the rock mechanical properties, degree of damage and energy evolution. Simulation results showed that tension rock bolts can improve the mechanical properties and energy storage capacities of the anchor. The energy evolution was divided into three stages: (i) the external work was stored in the form of elastic strain energy ( U e ) in the anchor prior to the yielding strength; (ii) the elastic strain energy reached its maximum near the peak strength; (iii) energy was dissipated from fracture friction ( W f) , plastic deformation ( W p ) and acoustic emission ( U r ) during post-peak stage. The installation of tension rock bolts was more suitable for medium hard rock (e.g. sandy mudstone), whereas it was not effective for hard rock (e.g. sandstone).

scholarly journals Study on the Meso-Energy Damage Evolution Mechanism of Single-Joint Sandstone under Uniaxial and Biaxial Compression

2021 ◽  
Vol 2021 ◽  
pp. 1-27
Author(s):  
Gui-Lin Wang ◽  
Tian-Ci Cao ◽  
Fan Sun ◽  
Xing-Xiang Wen ◽  
Liang Zhang
Keyword(s):  
Elastic Strain ◽  
Strain Energy ◽  
Elastic Strain Energy ◽  
Confining Pressure ◽  
Biaxial Compression ◽  
Level Energy ◽  
Energy Evolution ◽  
Peak Point ◽  
Joint Inclination ◽  
Joint Length

Energy conversion and release occur through the entire deformation and failure process in jointed rock masses, and the accumulation and dissipation of rock mass energy in engineering can reveal the entire process of deformation and instability. This study uses PFC2D to carry out numerical simulation tests on single-joint sandstone under uniaxial compression and biaxial compression, respectively, and analyse the influence of joint inclination, length, and confining pressure on the meso-energy conversion process and phase evolution of jointed sandstone. Through analysis, it is found that the input meso total strain energy is transformed into meso dissipated energy and meso-elastic strain energy. Macroscopic and microscopic joint sandstone law is consistent with the overall energy evolution; and the difference is reflected in two aspects: (1) the microlevel energy evolution has no initial compaction energy consumption section and (2) the linear energy storage section before the macroenergy evolution peak can be subdivided into two sections in the meso-level energy evolution. Under uniaxial compression, the energy values at the characteristic points of the meso-level energy evolution phases first asymmetrically decrease and then increase with the increase of the joint inclination. The initiation point of jointed sandstone is significantly affected by the length of the joint, and the degradation effect of the meso-energy at the damage point and peak point weakens with the increase of the joint length. Comparing the data obtained from the PFC numerical simulation with the experimental data, it is found that the error is small, which shows the feasibility of the numerical model in this paper. Under biaxial compression, the accumulation rate of meso-elastic strain at the peak point of the jointed sandstone first decreases and then increases with the joint inclination angle. After the peak of jointed sandstone, the rate of sudden change of meso-energy change decreases with the increase of joint length. The conditions of high confining pressure will promote the meso-accumulated damage degree of the jointed sandstone before the peak, while inhibiting the meso-energy and the mutation degree of the damage after the peak. The higher the confining pressure, the more obvious the joint length and inclination effect characteristics of the elastic strain energy at the peak point of the jointed sandstone.

scholarly journals An Experimental Investigation of the Progressive Failure of Sandstone and Its Energy Evolution Characteristics

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Yan Chen ◽  
Baohua Guo
Keyword(s):  
Crack Propagation ◽  
Crack Closure ◽  
Progressive Failure ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Energy Evolution ◽  
Evolution Characteristics ◽  
Confining Pressures ◽  
The Relationship

In this research study, the progressive failure and energy evolution characteristics of sandstone samples with different sizes were explored under uniaxial and triaxial compression conditions. The characteristic stresses and strains were captured using the crack axial strain levels and dissipative energy. The results showed that, with the increase in the ratios of the height to diameter (H/D), the crack closure stresses increased, while the crack damage stresses decreased. However, the levels of both the crack closure stresses and crack damages were observed to increase with the H/D. With increase in the confining pressure, it was found that the crack closure and crack damage stresses increased, while their levels decreased. The strains of the crack closures, peak crack axial, and crack propagation were observed to decrease with the H/D, while the crack closure strain levels increased. Also, the crack propagation strains were observed to increase with the confining pressures, while the crack closure, peak crack axial, and crack closure strain levels decreased. The progress failure of the sandstone samples was also obtained based on the evolution characteristics of the dissipative energy. The relationship between the energy densities during each phase and the H/D was also analyzed. It was determined that, with the increasing of the H/D, the input, elastic, and dissipative energy densities displayed different evolution characteristics. Furthermore, with the increases in the characteristic stresses, the input and elastic energy densities were found to increase. The dissipative energy density displayed a slight increase with the increases in the peak strength, which resulted in variations with regard to the crack closures and crack damage stresses.

scholarly journals Determining crack initiation stress in unconventional shales based on strain energy evolution

2021 ◽  
Vol 18 (5) ◽  
pp. 642-652
Author(s):  
Jiali Ren ◽  
Yang Wang ◽  
De-Hua Han ◽  
Luanxiao Zhao ◽  
Teng Long ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Strain Energy ◽  
Failure Modes ◽  
Failure Process ◽  
Wellbore Stability ◽  
New Method ◽  
Lateral Strain ◽  
Energy Evolution ◽  
Crack Initiation Stress ◽  
Initiation Stress

Abstract Determining the crack initiation stress (Ci) for unconventional shale rocks is of critical importance in describing the entire failure process of unconventional shale reservoirs. We propose a new method to identify Ci values based on triaxial failure tests on four organic shale samples, attempting to improve the shortcomings of other methods. The new method is based on the relationship between crack development and strain energy evolution (SEE). Additionally, the proposed SEE method is compared with three widely used methods, including crack volumetric strain (CVS), moving point regression (MPR) and the lateral strain response (LSR), intending to examine the performance of different methods. The contrastive results indicate that the LSR method cannot determine Ci when the rock ruptures without volumetric dilatancy, which frequently occurs in the compression process of organic shales. Ci values obtained using the SEE method are consistent with those from the CVS and MPR methods. However, the proposed SEE method with a solid physical basis is more objective and stable than the CVS and MPR methods. The proposed method, from one aspect, compensates for the shortcomings of other methods when facing different failure modes in organic shales. From the other aspect, it provides a way to precisely determine Ci values for applications in wellbore stability evaluation and hydraulic fracturing design.

scholarly journals Experimental Investigation of Early-Warning Critical Energy for Strainbursts

2021 ◽  
Author(s):  
Wang Ling ◽  
Ruyu Yan ◽  
Zhang zhi ◽  
Xie Lei ◽  
Huang chuhui
Keyword(s):  
Acoustic Emission ◽  
Energy Dissipation ◽  
Early Warning ◽  
Elastic Strain ◽  
Strain Energy ◽  
Triaxial Compression ◽  
Elastic Strain Energy ◽  
Critical Energy ◽  
Input Energy ◽  
Energy Evolution

Abstract This research aimed to establish an early-warning critical energy for coal instability based on the energy theory and acoustic emission characteristics of coal under triaxial compression. To obtain an early-warning critical strain energy indicating the increase in the risk of coal instability, conventional triaxial compression and acoustic emission (AE) tests were carried out on coal specimens taken from a 980-m-deep mine with initial confining pressures of 10, 15, 20, 25, 30 and 35 MPa. Stress-strain relations, AE features, and energy evolution characteristics during triaxial compression were analyzed. It was found that the energy evolution and AE event count changes across different loading stages. With increasing axial stress, most of the input energy stored in the coal specimens was in the form of elastic strain energy and the AE event count was close to zero, indicating that the coal grains reach a state of balance. After the elastic deformation stage, a portion of the input energy was consumed by inelastic deformation. Once the stress level exceeded the volumetric compressibility–dilatancy transition stress, the AE event entered a period of relative quiet, and the rate of energy dissipation abruptly accelerated, indicating that the coal grains achieved another state of balance before THE instability or failure. The balance of the rock grains is broken again (AE event count and the rate of energy dissipation both increased dramatically), coal achieved the peak strength and instability soon. The point at which the dissipated energy ratio α increased rapidly or the starting point of a quiet period, indicates an increase in the risk of coal instability. The corresponding elastic strain energy accumulated within the coal can be regarded as a precursor to instability or strainburst. Accordingly, a fitting formula is presented to predict the early-warning critical energy for brittle coal subject to different minimum principal stress. The analysis results in this paper can be helpful in the assessment of coal instability risk.

scholarly journals Study on the Progressive Failure Characteristics of Coal in Uniaxial and Triaxial Compression Conditions Using 3D-Digital Image Correlation

Energies ◽  
2018 ◽  
Vol 11 (5) ◽  
pp. 1215 ◽  
Author(s):  
Yang Tang ◽  
Seisuke Okubo ◽  
Jiang Xu ◽  
Shoujian Peng
Keyword(s):  
Digital Image Correlation ◽  
Uniaxial Compression ◽  
Digital Image ◽  
Progressive Failure ◽  
Triaxial Compression ◽  
Failure Process ◽  
Volumetric Strain ◽  
Image Correlation ◽  
Energy Evolution ◽  
3D Digital Image Correlation

To investigate the progressive failure process of coal, a series of uniaxial and triaxial compression tests were conducted and a novel 3D digital image correlation instrument with six cameras combined with a special transparent pressure cell was used for the strain measurement. The stress thresholds of coal were obtained in uniaxial and triaxial compression. The energy evolution during the compression was discussed, coupled with the crack volumetric strain. The field strain of the whole specimen surface and crack propagation at different stress levels were described to study the progressive failure mechanism of coal. The average stress level of crack initiation and crack damage of coal in uniaxial compression are 43.75% and 63.03%, while that in the triaxial compression are 74.53% and 89.84%, respectively. The dissipation energy evolution corresponds to the crack volumetric strain, while the elastic energy release leads to flake ejection and coal failure. The crack evolution and localization of coal indicated the progressive failure process that the coal sample undergoes in tension failure in uniaxial compression and in tension-shear failure in triaxial compression. The findings of this study can serve as a reference to understand the failure process of coal and improve the stability and safety of mining engineering.

scholarly journals An Energy Preservation Index for Evaluating the Rockburst Potential Based on Energy Evolution

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3636
Author(s):  
Lin Gao ◽  
Feng Gao ◽  
Yan Xing ◽  
Zhizhen Zhang
Keyword(s):  
Elastic Strain ◽  
Strain Energy ◽  
Failure Modes ◽  
Elastic Strain Energy ◽  
Rock Deformation ◽  
Energy Evolution ◽  
Deformation And Failure ◽  
Rock Materials ◽  
Energy Preservation ◽  
Evolution Characteristics

The estimation of rockburst potential has attracted great attention in the field of rock mechanics and engineering. In this study, an original energy preservation index is proposed to evaluate the rockburst potential in view of the energy evolution characteristics of rock materials. To investigate the energy evolution during rock deformation and failure, a number of cyclic uniaxial compression experiments on five kinds of rocks were carried out. The results showed that the curves of energy evolution exhibited obvious stages and there were significantly different weakening degrees for different rock materials embodied by the decreasing degrees of the ratios of elastic strain energy to dissipated strain energy at the weakening stage. Then, the energy preservation index was further formulated based on the decreasing ratio. Furthermore, by analyzing the acoustic emission activities at the failure stage and failure modes of the five rock materials, the rockburst potential was analyzed according to the energy preservation index.

Prediction and evaluation of fatigue life via modified energy method considering surface processing

2021 ◽  
pp. 105678952110451
Author(s):  
Haijie Wang ◽  
Xintian Liu ◽  
Tie Chen ◽  
Shen Xu
Keyword(s):  
Fatigue Life ◽  
Strain Energy ◽  
Life Prediction ◽  
Failure Process ◽  
Prediction Method ◽  
Test Results ◽  
Surface Processing ◽  
Plastic Strain Energy ◽  
The Relationship ◽  
Effect Of Surface

To predict fatigue life more accurately, we consider the relationship between static toughness and fatigue toughness in fatigue failure process, the numerical model of total dissipated plastic strain energy (TDPSE) and fatigue life is established. And considering the effect of surface roughness and surface processing coefficient on fatigue life, the life prediction method of TDPSE is modified. In addition, the fatigue life of Non-Masing and Masing materials are predicted by TDPSE and modified TDPSE method, respectively. Compared with TDPSE method, the life estimated by the modified TDPSE method are closer to the test results, and the modified TDPSE method lays a technical foundation for the development of mechanical components.

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