scholarly journals Experimental Study on the Relationship between Compression Stability and Deformation Localization of Viscous/Brittle Rock-Like Materials

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiangfeng Lv ◽  
Yahan Yang ◽  
Yan Chen ◽  
Nianjin Wang ◽  
Min Yang ◽  
...  
Keyword(s):  
Physical Map ◽  
Quantitative Description ◽  
Test Method ◽  
Brittle Rock ◽  
Deformation Localization ◽  
Deformation And Failure ◽  
Deformation Stage ◽  
Compression Deformation ◽  
Localization Zone ◽  
Monitoring Test

Rock-like materials often exhibit irregular failure deformation under long-term service conditions, and the deformation and failure of asphalt and concrete materials is a serious problem that leads to subgrade failure. In this study, two different viscous/brittle rock-like materials were prepared by the in situ loading and optical speckle synchronous monitoring test method, and the evolution characteristics of the deformation field were studied during compression. The formation process of the compression deformation localization of rock-like materials and their relationship with stability were analyzed. A quantitative description of the compression deformation stage and localization characteristics of the viscous/brittle rock-like materials is presented. The results can be summarized as follows. At the initial stage of compression, the deformation localization zone of viscous/brittle rock-like materials begins to expand from the middle area to the surrounding area. Preliminary results of the deformation localization of the linear elastic deformation stage were obtained. The failure cloud image is completely formed at the peak, which is consistent with the failure physical map. The deformation process of compression can be quantitatively described using the deformation localization characteristics of rock-like materials.

Influence of Cavity above Tunnel on Stratum Deformation and Failure in Urban Tunnelling

2012 ◽  
Vol 170-173 ◽  
pp. 1810-1815
Author(s):  
Yanan Zhang ◽  
Cheng Ping Zhang ◽  
Qian Qian Li ◽  
Zheng Li ◽  
Yi Cai
Keyword(s):  
Failure Process ◽  
Test Method ◽  
Test Results ◽  
Tunnel Engineering ◽  
Deformation And Failure ◽  
Tunnel Section ◽  
Section Size ◽  
Ground Cavity ◽  
Stratum Deformation ◽  
Beijing Subway

In order to study the influence of cavity above the tunnel on stratum deformation and failure in urban tunnelling, the model test method was adopted based on the parameters of the stratum and tunnel section size in Beijing subway. The stratum responses were obtained under the conditions without ground cavity and with ground cavity above the tunnel. The responses include the stratum stress distribution, stratum settlement law and stratum failure process. It was concluded that the existence of ground cavity above the tunnel worsened the stratum condition and accelerated the progress of stratum deformation and failure. Furthermore, the failure began from the cavity and the damage scope was bigger than that under the condition without cavity according to the test results. The research results can be referenced for the similar tunnel engineering.

scholarly journals Deformation and Failure Characteristics and Control Technology of Roadway Surrounding Rock in Deep Coal Mines

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Jucai Chang ◽  
Dong Li ◽  
Tengfei Xie ◽  
Wenbao Shi ◽  
Kai He
Keyword(s):  
High Stress ◽  
Development Stage ◽  
Surrounding Rock ◽  
Deformation And Failure ◽  
Deformation Stage ◽  
Mining Depth ◽  
Floor Heave ◽  
Rock Tunnel ◽  
Two Sides

With the increase in mining depth, the problem of the floor heave of a roadway is becoming increasingly prominent. Solving this problem for a deep high-stress roadway is the key to ensure safe supply and utilization of coal resources in China. This study investigates the floor heave of a horizontal transportation rock roadway at the depth of 960 m at the Xieyi Mine. A four-way loading simulation test frame similar to the Xieyi Mine was used to reproduce the high-stress environment of a deep roadway by loading different pressures on the roof, floor, and two sides of the roadway. The experimental results show that after the tunnel had been excavated, the surrounding rock failure could be divided into three stages: the initial deformation stage, fissure development stage, and mild deformation stage. The destruction time periods of these stages were 0–0.5 h, 0.5–2 h, and 2–6 h, and the destruction ranges were 0.4 m, 1 m, and 1.5 m, respectively. The amount of roof subsidence, the displacement of the two sides, and the floor heave influence each other, and the range of the bearing ring (5.6 m) of the floor is larger than that of the roof (3.4 m) after the surrounding rock has been damaged. The findings suggest that the floor should be supported first, before the two sides and the roof; then, the support of the key parts (roof and floor corners) should be strengthened. The roof, floor, and two sides are considered for controlling the deformation of the surrounding rock in a coupled trinity support mode. Because of the unfavorable conditions in the area, overexcavation backfill technology was used. The new support was successfully applied during the subsequent construction of the rock tunnel. Based on the long-term monitoring results of the surrounding rock deformation, the floor heave control yielded satisfactory results and maintained the long-term stability of the roadway. Therefore, this study can serve as a reference for preventing floor heave in similar high-stress roadways in the future.

scholarly journals Study of Damage Constitutive Model of Brittle Rocks considering Stress Dropping Characteristics

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Fei Li ◽  
Shuang You ◽  
Hongguang Ji ◽  
Hao Wang
Keyword(s):  
Constitutive Model ◽  
Triaxial Compression ◽  
Strain Curve ◽  
Brittle Rock ◽  
Model Parameters ◽  
Deformation And Failure ◽  
Brittle Rocks ◽  
Whole Process ◽  
Confining Pressures ◽  
Damage Constitutive Model

Deep brittle rock exhibits characteristics of rapid stress dropping rate and large stress dropping degree after peak failure. To simulate the whole process of deformation and failure of the deep brittle rock under load, the Lemaitre strain equivalent theory is modified to make the damaged part of the rock has residual stress. Based on the damage constitutive model considering residual strength characteristics, a correction factor reflecting stress dropping rate is added, the Weibull distribution is used to describe the inhomogeneity of rock materials, and Drucker–Prager criterion is used to quantitatively describe the influence of stress on damage; a damage constitutive model of deep brittle rock considering stress dropping characteristics is established. According to the geometric features of the rock stress-strain curve, the theoretical expressions of model parameters are derived. To verify the rationality of the model, triaxial compression experiments of deep brittle rock under different confining pressures are conducted. And the influence of model parameters on rock mechanical behaviour is analysed. The results show that the model reflects the stress dropping characteristics of deep brittle rock and the theoretical curve is in good agreement with the experimental results, which indicates that the proposed constitutive model is scientific and feasible.

Research on the Conversion Relationship for Three-Point Bending Specimen With Fixed Constraints in the Large Deformation Stage

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Hai-Yang Yu ◽  
Guo-Yan Zhou ◽  
Fa-Kun Zhuang
Keyword(s):  
Large Deformation ◽  
Creep Test ◽  
Geometric Parameters ◽  
Test Method ◽  
Three Point Bending ◽  
Deformation Stage ◽  
Creep Stress ◽  
Uniaxial Creep ◽  
Conversion Coefficients ◽  
Beam Bending

Abstract In this study, based on the rod tensile model, a conversion relationship between three-point bending specimen with fixed constraints (TPBSF) and uniaxial creep data in the large deformation stage is defined by the reference stress method. Using finite element method, conversion coefficients are determined. Then it is verified by the creep test data of A7N01 at 350 °C (Zhuang, F. K., 2014, “Research on Creep Test Method of Small Specimen Based on Beam Bending Theory,” Ph.D. thesis, East China University of Science and Technology, Shanghai, China). The results show that creep stress exponent n is the same, but creep constant B obtained by rod tensile model is much closer to uniaxial creep than beam bending model. Finally, effects of geometric parameters and friction on conversion coefficients are investigated. On this basis, the specimen cross section aspect ratio greater than 1 and the indenter radius larger than 1 mm are recommended to minimize the influence of TPBSF geometric parameters on conversion coefficients. The influence of friction on conversion coefficients can be negligible.

Structural Analysis of Compression Deformation and Failure of Aluminum in Fire

2011 ◽  
Vol 137 (7) ◽  
pp. 728-738 ◽  
Author(s):  
S. Feih ◽  
E. Kandare ◽  
B. Y. Lattimer ◽  
A. P. Mouritz
Keyword(s):  
Structural Analysis ◽  
Deformation And Failure ◽  
Compression Deformation ◽  
In Fire

scholarly journals A Test Method for Creep Characteristics of Loess Based on the One-Dimensional Consolidator

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Rongbin Huang ◽  
Shuangming Wang ◽  
Shuancheng Gu ◽  
Zhengjun Mao
Keyword(s):  
Influence Factors ◽  
Test Method ◽  
Creep Process ◽  
Deformation And Failure ◽  
Creep Stage ◽  
One Dimensional ◽  
Process Characteristics ◽  
Whole Process ◽  
Creep Characteristics ◽  
Accelerated Creep

When the traditional one-dimensional consolidator is used to study the creep characteristics of loess, due to the hoop effect of the ring cutter, only the attenuation creep stage and stable creep stage of loess can be studied, but the accelerated creep stage cannot be presented. In order to avoid the influence of drilling on the creep characteristics of loess, the paper improves the consolidation instrument by drilling holes along the diameter direction in the center of the sample to provide artificial space for soil failure. At the same time, the sample size is increased to ensure that the diameter of the sample is greater than five times of the diameter of the borehole, so as to avoid the influence of drilling on the creep characteristics of loess. The creep characteristics of loess are studied by step loading (vertical pressure at all levels is 125 kPa, 175 Pa, 225 kPa, and 275 kPa), and the whole creep process characteristic curves of loess under different stress conditions are obtained. An endoscope was placed in the hole to observe the deformation and failure characteristics of loess in different stages of creep. This method makes up for the defect that the traditional one-dimensional consolidator cannot obtain the whole process characteristics of loess creep. At the same time, it has the advantages of simple operation, less external influence factors, stronger data reliability, and can directly observe the changes of loess creep soil. It has a beneficial role in promoting the experimental research of loess creep characteristics.

scholarly journals PENERAPAN PENDEKATAN PRAGMATIK (PRINSIP-PRINSIP PENGGUNAAN BAHASA) DISERTAI TEKNIK KOREKSI SESAMA TEMANDAN KOREKSI OLEH GURU UNTUK MENINGKATKAN KETERAMPILAN MENCERITAKAN PENGALAMAN PADA SISWA KELAS VIIE SMP NEGERI 5 NEGARA

2013 ◽  
Vol 3 (2) ◽  
pp. 110-121
Author(s):  
I Putu Mas Dewantara
Keyword(s):  
Language Use ◽  
Quantitative Description ◽  
Test Method ◽  
Qualitative Description ◽  
Learning Activity ◽  
Pragmatic Approach ◽  
Learning And Teaching ◽  
Correction Technique ◽  
Questionnaire Method ◽  
Teaching Learning

This research was intended to (1) describe the development of telling experience skill of the students of class VII E SMP Negeri 5 Negara through the implementation of pragmatic approach (principles of language use) accompanied by pair correction technique and correction by Teacher, (2) describe the steps of learning and teaching activities in the implementation of pragmatic approach (principles of language use) accompanied by pair correction technique and correction by Teacher to develop the skill of telling experiences by the students of VII E SMP Negeri 5 Negara, and (3) describe students’ response about the implementation of pragmatic approach (principles of language use) accompanied by pair correction technique and correction by teacher. The subjects of this research were students and teacher of bahasa Indonesia in SMP Negeri 5 Negara. This research used the two-cycle classroom action research. The data about the skill of telling experiences was gathered through test method analyzed by qualitative description method. The data about students’ response was gathered through questionnaire method analyzed by qualitative description and quantitative description. The result of the research showed that the implementation of pragmatic approach (principles of language use) accompanied by pair correction technique and correction by teacher can (1) develop the skill of telling experience by students, (2) be done through 19 appropriate learning steps, and (3) develop students’ positive response in telling experience. Bahasa Indonesia’s teachers is hoped to implement the pragmatic approach (principles of language use) accompanied by pair correction technique and correction by teacher to develop the skill of telling students’ experiences that make the teaching-learning activity can run conducive, creative, and innovative.

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