Experimental Research on Creep Laws of High-Water Material under Real Pressure Water Environment

2016 ◽  
Vol 705 ◽  
pp. 350-354
Author(s):  
Hui Xie ◽  
Ying Chen
Keyword(s):  
Experimental Research ◽  
Carrying Capacity ◽  
Water Pressure ◽  
Water Environment ◽  
High Water ◽  
Term Strength ◽  
Steady Creep ◽  
Creep Tests ◽  
Pressure Water

High-water material is a kind of new inorganic nonmetal material which mainly used in coal mine goaf filling. In order to simulate the real stress conditions of this material in goaf filling, the creep tests of high-water material in real pressure water environment were conducted and the creep laws were also researched. The results showed that water environment was conductive to maintaining and developing the strength of high-water material, and pressure water environment can improve the carrying capacity and long-term strength of high-water material. The deformation of steady creep period decreased while water pressure increased. And strain increasing caused by axial compression was less than strain increasing caused by water pressure. The time needed from starting to steady creep period was longer when water pressure was bigger.

scholarly journals Analysis on Water Inrush Process of Tunnel with Large Buried Depth and High Water Pressure

Processes ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 134 ◽  
Author(s):  
Weimin Yang ◽  
Zhongdong Fang ◽  
Hao Wang ◽  
Liping Li ◽  
Shaoshuai Shi ◽  
...  
Keyword(s):  
High Pressure ◽  
Model Test ◽  
Water Pressure ◽  
Water Inrush ◽  
High Water ◽  
Surrounding Rock ◽  
Karst Cave ◽  
Tunnel Excavation ◽  
Pressure Water ◽  
High Water Pressure

In order to explore the catastrophic evolution process for karst cave water inrush in large buried depth and high water pressure tunnels, a model test system was developed, and a similar fluid–solid coupled material was found. A model of the catastrophic evolution of water inrush was developed based on the Xiema Tunnel, and the experimental section was simulated using the finite element method. By analyzing the interaction between groundwater and the surrounding rocks during tunnel excavation, the law of occurrence of water inrush disaster was summarized. The water inrush process of a karst cave containing high-pressure water was divided into three stages: the production of a water flowing fracture, the expansion of the water flowing fracture, and the connection of the water flowing fracture. The main cause of water inrush in karst caves is the penetration and weakening of high-pressure water on the surrounding rock. This effect is becoming more and more obvious as tunnel excavation progresses. The numerical simulation results showed that the outburst prevention thickness of the surrounding rock is 4.5 m, and that of the model test result is 5 m. Thus, the results of the two methods are relatively close to each other. This work is important for studying the impact of groundwater on underground engineering, and it is of great significance to avoid water inrush in tunnels.

scholarly journals Evaluating Long-Term Strength and Time to Failure of Sandstone with Different Initial Damage

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Rongbin Hou ◽  
Yanke Shi ◽  
Leige Xu ◽  
Jinwei Fu ◽  
Kai Zhang
Keyword(s):  
Failure Time ◽  
Term Strength ◽  
Steady Creep ◽  
Creep Failure ◽  
Damage State ◽  
Term Stability ◽  
Long Term Stability ◽  
Creep Stress ◽  
Initial Damage

Long-term strength (LTS) of rock materials is important for the long-term stability analysis and the failure prediction of structures in rock engineering. Numerous studies have been carried out on the LTS for various kinds of rock; however, the effects of initial damage on the LTS and creep failure time of rock have not been conducted. In the present study, the creep experiment with controllable initial damage state of rock was designed. Then, the LTS of rock specimens with different initial damage was determined by four methods (i.e., the isochronous stress-strain curve method, the steady creep discriminated method, the volumetric strain inflexion point determined method, and the intersection of the steady creep rate method). The results show that, with the increase in the initial damage, the LTS of rock decreases and the relationship between the initial damage and the LTS of rock can be described as a linear function. Finally, an evaluation method for predicting the creep failure time of rock under a single stress level was proposed. In addition, the creep failure time of rock with different initial damage under different creep stress levels was obtained by the method. The results indicate that both the initial damage and the creep stress levels have a great influence on creep failure time, i.e., greater initial damage or creep stress leads to a shorter period for rock failure. Thus, for analyzing the long-term stability of rock mass structure, not only the influence of in situ stress but also the initial damage state of the surrounding rock should be considered.

scholarly journals The implosion of cylindrical shell structures in a high-pressure water environment

2013 ◽  
Vol 469 (2160) ◽  
pp. 20130443 ◽  
Author(s):  
C. M. Ikeda ◽  
J. Wilkerling ◽  
J. H. Duncan
Keyword(s):  
High Pressure ◽  
Cylindrical Shell ◽  
Time Scale ◽  
Water Pressure ◽  
Water Environment ◽  
Mode Number ◽  
Shell Structures ◽  
Internal Diameter ◽  
Cross Sectional ◽  
Pressure Water

The implosion of cylindrical shell structures in a high-pressure water environment is studied experimentally. The shell structures are made from thin-walled aluminium and brass tubes with circular cross sections and internal clearance-fit aluminium end caps. The structures are filled with air at atmospheric pressure. The implosions are created in a high-pressure tank with a nominal internal diameter of 1.77 m by raising the ambient water pressure slowly to a value, P c , just above the elastic stability limit of each shell structure. The implosion events are photographed with a high-speed digital movie camera, and the pressure waves are measured simultaneously with an array of underwater blast sensors. For the models with larger values of length-to-diameter ratio, L / D 0 , the tubes flatten during implosion with a two-lobe (mode 2) cross-sectional shape. In these cases, it is found that the pressure wave records scale primarily with P c and the time scale (where R i is the internal radius of the tube and ρ is the density of water), whereas the details of the structural design produce only secondary effects. In cases with smaller values of L / D 0 , the models implode with higher-mode cross-sectional shapes. Pressure signals are compared for various mode-number implosions of models with the same available energy, P c V , where V is the internal air-filled volume of the model. It is found that the pressure records scale well temporally with the time scale , but that the shape and amplitudes of the pressure records are strongly affected by the mode number.

scholarly journals Effect of Moisture Content On The Time-Dependent Mechanical Characteristics of Loess

2021 ◽  
Author(s):  
Lijie Chen ◽  
Jianbing Peng ◽  
Fei Xie ◽  
Yanqiu Leng ◽  
Penghui Ma ◽  
...  
Keyword(s):  
Moisture Content ◽  
Failure Mode ◽  
Shear Failure ◽  
Time Dependent ◽  
Shanxi Province ◽  
Peak Strain ◽  
Term Strength ◽  
Creep Tests ◽  
Effect Of Moisture

Abstract It is of great significance to study the time-dependent mechanical properties of loess, as loess landslides are closely related to them. The purpose of this study is to investigate the effect of moisture content on instantaneous and time-dependent deformation, strength and failure behaviors of undisturbed loess specimens from Nangou in Yan'an City, Shanxi Province, China, via triaxial shearing tests and multi-loading triaxial creep tests under moisture contents of 5%, 10%, 17% and 22%. The results show that the time-dependent deformation of loess increase with the moisture content, while the time-dependent deformation rate decreases slowly. The soil deformation is divided into four stages based on the peak strain rate. Furthermore, the instantaneous and long-term strength of loess decrease with increasing moisture content, and the instantaneous strength decreases more than the long-term strength. The failure mode of undisturbed loess changes from shear failure to homogeneous failure with increasing moisture content; when the failure mode is shear failure, the thickness of the shear band that forms at the specimen surface over time is smaller than the corresponding thickness that forms instantaneously. Finally, the macroscopic morphology and microstructure of loess specimens were considered together to analyze the effect of moisture content on the instantaneous and long-term mechanical behavior of loess and to discuss the process of loess deformation to failure.

scholarly journals Long-Term Strength of Porous Geomaterials by a Micromechanical Model considering Alternate Wetting and Drying Condition

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Jin Zhang ◽  
Shirong Fu ◽  
Tao Ni ◽  
Bei Han ◽  
Chong Shi
Keyword(s):  
Water Pressure ◽  
Micromechanical Model ◽  
Boundary Surface ◽  
Solid Matrix ◽  
Term Strength ◽  
Wetting And Drying ◽  
Alternate Wetting And Drying ◽  
Drying Condition ◽  
Variable Water

This study is devoted to determining the long-term strength of porous geomaterials under alternate wetting and drying condition by statical shakedown analysis. In the framework of micromechanics of porous materials, Gurson’s hollow sphere model with Drucker-Prager solid matrix is adopted as the representative volume element. The effects of alternate wetting and drying are considered as variable water pressure imposed on the inner boundary surface of the unit cell. The cyclic responses are separated as a pure hydrostatic part under compressive/tensive loads and an additional deviatoric part to capture shear effects. The reduction of the long-term strength due to inner water pressure is observed by the illustration of obtained macroscopic criteria with respect to various load parameters. In addition, the accuracy of the analytical solution is also verified by comparing to the results of FEM-based step-by-step computations.

Study on Automatic Monitoring Technology of Tunnel Crossing Coal Bed and Gas

2014 ◽  
Vol 488-489 ◽  
pp. 778-781
Author(s):  
Cong He
Keyword(s):  
Evaluation Method ◽  
Water Pressure ◽  
Automatic Monitoring ◽  
High Water ◽  
Western China ◽  
Coal Bed ◽  
Key Factors ◽  
Pressure Water ◽  
Mixing Method ◽  
Specific Implementation

Based on a tunnel in western China as a project, with high water pressure, water-rich, karst features and other projects, launched grouting water research, the cement-silicate slurry mixing method for determining the mixing ratio to ensure the effectiveness and construction safety grouting key factors, as well as the specific implementation grouting effect evaluation method has important theoretical and practical value for the design and construction of similar tunnels provide a reference.

scholarly journals Experimental Study on the Creep Characteristics of Cemented Backfill in a Goaf under Water Pressure

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
JingYu Zhang ◽  
Huafeng Deng ◽  
GuoYong Duan ◽  
LiangPeng Wan ◽  
Zuosen Luo ◽  
...  
Keyword(s):  
Creep Rate ◽  
Creep Strain ◽  
Axial Stress ◽  
Water Pressure ◽  
Steady Creep ◽  
Long Term Stability ◽  
Groundwater Environment ◽  
Creep Characteristics ◽  
North Water

As the groundwater environment changes in a goaf, the creep deformation of the backfill underwater pressure is worthy of attention. This paper takes the undercut goaf filling in the Yuzhou section of the middle route of the South-to-North Water Transfer Project as an example. Grading loading creep testing of the backfill under different water pressures was carried out using equipment developed by our research team. Based on the experimental results, the following key points were observed: (1) under the same axial stress, the creep strain and steady creep rate increase with increasing water pressure. Under the same water pressure, the creep strain and steady creep rate also increase with increasing axial stress. (2) The long-term strength of a backfill sample decreases with increasing water pressure and has a nonlinear relationship with water pressure. (3) The increase in water pressure exacerbates the damage of a backfill sample, which is manifested by the secondary crack propagation at the time of failure. Therefore, the increase in water pressure degrades the mechanical properties of the backfill to some extent. The results of this paper provide a reliable theoretical basis for the long-term stability analysis of goaf filling underwater pressure.

Denitrification of groundwater: pilot-plant testing of cotton-packed bioreactor and post-microfiltration

2000 ◽  
Vol 42 (1-2) ◽  
pp. 353-359 ◽  
Author(s):  
M. I. Soares ◽  
A. Brenner ◽  
A. Yevzori ◽  
R. Messalem ◽  
Y. Leroux ◽  
...  
Keyword(s):  
Drinking Water ◽  
Carbon Source ◽  
Feed Rate ◽  
Pilot Plant ◽  
Water Pressure ◽  
High Water ◽  
Crossflow Microfiltration ◽  
Number Of Bacteria ◽  
High Water Pressure

The use of raw cotton as carbon source in the denitrification of drinking water was tested in a field pilot-plant. The reactor treated water from a well in which the concentration of nitrate varied from 22 mg N l–1 in summer to a minimum of 9 mg l–1 in winter. The experimental reactor had a capacity of approximately 9 m3 and could be packed with up to 1500 kg of unprocessed cotton. The highest rate of denitrification observed was 0.36 kg N m–3 d–1, at a feed rate of 6 m3 h–1. However, this performance could be sustained only temporarily as the relatively high water pressure caused serious compression of the bed. The long-term (six months) performance of the system was studied at feed rates of 0.8 and 1.5 m3 h–1. The process was stable and 80–100% of the influent nitrogen was removed. The increase in DOC at the outlet was usually less than 7 mg l–1, and the number of bacteria was in the order of 105–106 CFU ml–1. Crossflow microfiltration was an effective post-treatment for the removal of bacteria and elimination of turbidity.

Experimental Study on Direct Shear Creep Characteristics and Long-Term Strength of Red Layer Sliding Zone Soil in Southern Hunan

2013 ◽  
Vol 842 ◽  
pp. 782-787 ◽  
Author(s):  
Feng Zhu ◽  
Zhong Yuan Duan ◽  
Zhen Yu Wu ◽  
Yu Qi Wu ◽  
Tian Long Li ◽  
...  
Keyword(s):  
Shear Stress ◽  
Term Strength ◽  
Direct Shear ◽  
Creep Tests ◽  
Shear Creep ◽  
Creep Characteristics ◽  
Southern Hunan ◽  
Sliding Soil ◽  
Sliding Zone

The creep characteristics of red layer sliding soil under the condition of different vertical loads and water contents were studied through a series of direct shear creep tests. Tests results showed that the water infiltrated to the sliding zone along the fissure of red layer sliding belt due to the crush of red layer sliding rock, leading to softening of sliding zone and acceleration of shear creep. When the shear stress reached the limit of long-term shear strength, sliding soil was broken suddenly with small vertical loads (50 kPa and 100kPa), while the sliding soil presented as a constant acceleration creep with enough vertical loads (200 kPa and 300 kPa). The inflection point in shear stress-shear displacement isochronous curve corresponded to the long-term strength of the soil.

Study on Grouting Comprehensive Technical of Karst Tunnel with Water-Rich and High-Pressure

2014 ◽  
Vol 488-489 ◽  
pp. 786-789
Author(s):  
Yu Lin Zou
Keyword(s):  
Evaluation Method ◽  
Water Pressure ◽  
High Water ◽  
Western China ◽  
Effect Evaluation ◽  
Key Factors ◽  
Karst Tunnel ◽  
Pressure Water ◽  
Mixing Method ◽  
Specific Implementation

Based on a tunnel in western China as a project, with high water pressure, water-rich, karst features and other projects, launched grouting water research, the cement-silicate slurry mixing method for determining the mixing ratio to ensure the effectiveness and construction safety grouting key factors, as well as the specific implementation grouting effect evaluation method has important theoretical and practical value for the design and construction of similar tunnels provide a reference.

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