scholarly journals Research improvement of the strength characteristics of rocks under volumetric compression

2021 ◽  
Vol 315 ◽  
pp. 01012
Author(s):  
Eugeny Pudov ◽  
Nikolay Bedarev ◽  
Vitaly Shakhmanov ◽  
Oleg Lyubimov
Keyword(s):  
Rock Strength ◽  
Strength Characteristics ◽  
Special Device ◽  
Test Results ◽  
Rock Samples ◽  
Scope Of Application ◽  
Complex Equipment ◽  
Compression Chamber

The article describes some aspects of the research and applied works, which the authors carried out to expand the scope of application in the study of rock strength indicators in the laboratory of KuzSTU (Prokopyevsk branch) on a complex equipment. It consists of an extreme deformation chamber and a volumetric compression chamber. It describes the disadvantages of the volumetric compression chamber. The disadvantages have been eliminated by using a special device for fixing the sample when descending into the volumetric compression chamber. The article also gives the description of the operation of a volumetric compression chamber with the possibility of testing rock samples for a breakage under the volumetric compression. The first test results are presented.

scholarly journals Analysis and Disposal of Typical Breakdown Failure for Resin Impregnated Paper Bushing in the Valve Side of HVDC Converter Transformer

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4303 ◽  
Author(s):  
Hao Tang ◽  
Guangning Wu ◽  
Ming Chen ◽  
Jiang Deng ◽  
Xining Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fault Current ◽  
Special Device ◽  
Test Results ◽  
The Finite Element Method ◽  
Load Current ◽  
High Voltage Direct Current ◽  
Root Cause ◽  
Current Characteristics

This paper presents analysis, diagnosis and disposal with a typical internal breakdown failure of the resin impregnated paper (RIP) valve side bushing in high voltage direct current (HVDC) converter transformer. Based on the analysis of fault current characteristics at the time of the RIP valve side bushing failure, and field test results of insulation parameters, a method of diagnosing typical breakdown failures of valve side bushings is proposed. Through disassembly inspection of the internal overheating and arcing traces on the failure bushing, the root cause of this typical breakdown failure is found, which is upper axial flashover along the RIP condenser/SF6 interface caused by the abnormal contact of two current-carrying conductive tubes. Temperature distribution inside the bushing with an abnormal contact resistance between the copper conductive tube and aluminum conductive tube under different load current is simulated by using the finite element method. An special device is also developed for repairing defective bushing on-site, and 75 bushings with conductive contact defects have been repaired on the premise of not pushing converter transformers away from the valve hall and even without pulling out defective bushings.

Experimental Study on the Engineering Characteristics of Improved Soil

2010 ◽  
Vol 168-170 ◽  
pp. 1426-1431
Author(s):  
Zhi Qing Li ◽  
Zhen Dong Cui ◽  
Yan Ping Wang ◽  
Li Chao Wang ◽  
Duo Zhong
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Fly Ash ◽  
Physical And Mechanical Properties ◽  
Hybrid Structure ◽  
Strength Characteristics ◽  
Shanxi Province ◽  
Hydration Reaction ◽  
Test Results ◽  
Shearing Strength

According to the typical loess in Shuozhou in Shanxi province, tests involved in compaction characteristics, shearing strength characteristics and disintegration are carried out by using loess and three kinds of improved loess, namely lime and fly-ash, lime and cement, cement and fly-ash. The best improved soil method is selected. The test results indicate that the compact hybrid structure is formed by fly ash and loess. The activity of fly ash is activated as a result of the lime mixing. A series of hydration reaction prompt the intensity of modified loess. And the physical and mechanical properties of improved loess are improved noticeably.

scholarly journals Korelasi Point Load Index dan Uniaxial Compressive Strength pada Satuan Batupasir dan Batulempung Formasi Latih untuk Penentuan Koefisien Kekuatan Batuan di Pit X Tambang Batubara PT Berau Coal, Kalimantan Timur

2021 ◽  
Vol 9 (1) ◽  
pp. 9-16
Author(s):  
Yan Adriansyah ◽  
Guruh Krisnantara ◽  
Kurniawan Setiadi
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Mining Industry ◽  
Point Load ◽  
Engineering Properties ◽  
Test Results ◽  
Rock Engineering ◽  
Point Load Index ◽  
Rock Samples ◽  
Laboratory Test Results

Physical and mechanical properties of rock for engineering purposes are indispensable for any civil/construction, mining and other engineering requirment. The results of the uniaxial compressive strength (UCS) test are very much needed in various geotechnical analyzes or engineering, in particular in the mining industry in relation to the calculation of the pit slope design and other mining infrastructure. Rock samples used in this study were obtained from the results of geotechnical drilling (full core drilling). The rock engineering properties test to obtain UCS and PLI values was carried out in the laboratory. Testing the rock hardness index using the point load index (PLI) can be done more quickly, cheaply, practically and can use rock samples with a variety of sample shapes.         The focus and object of the research are mudstone and sandstone units as part of the Lati Formation. These two types of layers are the most dominant rock types as a constituent of the pit slopes in the research area. To ensure that the correlation results are in accordance with the rules of scientific research, the distribution of UCS and PLI data from laboratory test results is verified using a statistical approach / testing. Correlation and analysis between the two rock engineering properties test results are very useful for geotechnical analysis data input. The coefficient or constant values obtained can be used to determine the rock strength values used in various geotechnical analyzes so that the analysis can be carried out more efficiently, effectively and quickly and can support geotechnical engineering work.

scholarly journals КОЭФФИЦИЕНТЫ ДЕГРАДАЦИИ ПРОЧНОСТИ СИЛОВЫХ ЭЛЕМЕНТОВ КУПОЛА ПАРАШЮТА ПОСЛЕ ДЛИТЕЛЬНОЙ ЭКСПЛУАТАЦИИ ИЛИ ХРАНЕНИЯ

2019 ◽  
pp. 62-71
Author(s):  
Петр Александрович Фомичев ◽  
Игорь Михайлович Сила
Keyword(s):  
Service Life ◽  
Breaking Load ◽  
Strength Characteristics ◽  
Test Results ◽  
Structural Elements ◽  
Term Operation ◽  
Lower Confidence ◽  
Strength Tests ◽  
Normal Law

The technique of processing the test results to the destruction of samples cut from slings and dome fabric after prolonged use or storage of the parachute is described. The normal law of load distribution before failure is adopted.It is proposed to find the minimum breaking load as the lower confidence limit depending on the number of tested samples and a confidence probability of 0.99.The results of strength tests of samples from the parachutes of the landing D-5 series 2 of 1983, the spare Z-5 of 1984, and the rescue S-5K series 2 of 1989 are presented.A total of 301 samples were tested, including 54 samples from slings D-5, 48 samples from slings Z-5 and S-5K, samples from fabrics of domes on the base and weft. Samples from slings were cut out at the edge of the dome, in the middle, at the arc buckles.Fabric samples were cut radially from the top to the edge of the dome. The dependence of the strength characteristics on the location of the samples along the length of the slings or the dome panel has not been established.There are no gross errors in the tests according to the Grubbs criterion.The strength degradation coefficients of the slings and fabrics of the domes are determined as the ratio of the breaking load after long-term operation or storage to the initial values adopted during the design.The proximity of the degradation coefficients of slings and dome fabrics was noted. Based on the set of test results in order to obtain the minimum values of the degradation coefficients, a linear dependence on the life of the parachute is established.This period should be counted from the year the parachute was made.The dependence of the minimum degradation coefficients (maximum degradation) on the service life makes it possible to assess the drop in the strength characteristics of the structural elements with increasing service life. This dependence allows you to predict the maximum allowable landing speed when deciding on the extension of the life of the parachute.

scholarly journals Comparison of fatigue characteristics of 38ХН3МФА and 40ХН high-tensile-strength steels based on test results

2020 ◽  
Vol 4 (394) ◽  
pp. 63-69
Author(s):  
Semyon D. Knoring ◽  
Victor V. Platonov ◽  
Nikolay G. Popov ◽  
Valery M. Shaposhnikov
Keyword(s):  
Fatigue Strength ◽  
Fresh Water ◽  
Strength Characteristics ◽  
Test Results ◽  
Cyclic Tests ◽  
40Kh Steel ◽  
Notched Specimens ◽  
Steel Grades ◽  
Fatigue Characteristics ◽  
Better Than

Object and purpose of research. The object of work is steel “38ХН3МФА”, planned for use in the propeller shafts manufacture of the lead-ship (project 10510), and less strong steel “40XH”, used in the propeller shafts manufacture for icebreakers of lower ice categories and lower power. The purpose of the study is to compare the fatigue strength of these steel grades. Materials and methods. Investigations of the fatigue strength characteristics of steels were carried out by cyclic tests of flat notched specimens in air and cylindrical specimens in fresh water. Main results. It is shown that lowest fatigue strength results correspond to external cyclic loading of specimens with stress concentrator (notch). But even in these conditions, fatigue strength of 38ХН3МФА steel is better than that of 40XH steel. As for the tests of smooth samples in fresh water, 38ХН3МФА steel also has a clear advantage over 40XH steel. Conclusion. The studies have shown that fatigue strength characteristics of 38ХН3МФА steel in the air and in corrosive environment exceed those of 40XH steel. Environmental sensitivity and stress concentration of 38ХН3МФА steel turned out to be higher than for 40KH steel.

Strength Attenuation Law of Damaged Rock Samples and its Structure Effect

2013 ◽  
Vol 353-356 ◽  
pp. 602-607
Author(s):  
Hai Jian Su ◽  
Hong Wen Jing ◽  
Chen Wang ◽  
Bo Meng
Keyword(s):  
Uniaxial Compression ◽  
Axial Compression ◽  
Confining Pressure ◽  
Structure Effect ◽  
Thick Wall ◽  
Test Results ◽  
Compression Tests ◽  
Rock Samples ◽  
Nonlinear Fitting ◽  
Attenuation Value

In order to study the post-peak mechanics behavior of rock samples with a thick wall cylinder structure, damaged rock samples were precast with a new method. The uniaxial compression tests and tri-axial compression tests were conducted on the samples and the test results were compared with that of complete rock samples. The results show that strength attenuation value of the damaged samples increased with the confining pressure and the specific relationship was obtained by nonlinear fitting as (is the strength attenuation value and is the confining pressure); destructiveness of damaged samples was more serious than the complete ones; a new nearly horizontal failure phenomenon appeared under the tri-axial compression and it was more general with the increase of confining pressure. Structure effect of uniaxial strength attenuation was revealed based on the particle flow software system (PFC) and the corresponding theoretical model was found as (is the strength attenuation value under uniaxial compression of any damaged sample with a thick wall cylinder structure; is the strength attenuation value of standard damaged samples under uniaxial compression; is the structure ratio, and are the parameters of the material). Characteristic value of the strength attenuation value under uniaxial compression was obtained by calculation when the structure ratio was indefinitely large.

Experimental Study on Strength Characteristics Comparison of Tamped and Poured Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 492-497
Author(s):  
Xi Yuan Liu ◽  
Yan Feng Li ◽  
Zhao Xia Chen ◽  
Ling Wang
Keyword(s):  
Compressive Strength ◽  
Influence Factors ◽  
Strength Characteristics ◽  
Test Results ◽  
Optimum Parameters ◽  
Foundation Treatment ◽  
Mix Proportion ◽  
Curing Condition ◽  
The Difference ◽  
The Cost

Piles formed by tamped concrete are a kind of technology in foundation treatment. In order to study the difference of strength characteristics between tamped and ordinary poured concrete, optimum parameters of mix proportion on tamped concrete are obtained by heavy compaction test in laboratory, then unconfined compressive strength tests are accomplished on the basis of optimum parameters of mix proportion. Influence factors of strength characteristics of tamped concrete are studied, such as cement-aggregate ratio, curing age, curing condition and so on. Finally, strength characteristics of tamped and ordinary poured concrete are compared. The test results indicate that the tamped concrete is hardened quickly and early-strength. In standard, water and saturated soil curing condition, compressive strength all grows sufficiency, thus tamped concrete can be used in ground and underground environment. At the same time, a higher strength can be obtained by smaller cement content, and the cost of tamped concrete can be reduced effectively.

Experimental Research on Brittle Shale Failure Caused by Drilling Fluid Activity

2013 ◽  
Vol 807-809 ◽  
pp. 2550-2553 ◽  
Author(s):  
Ming Wang Peng ◽  
Hang Wen ◽  
Wei Zhou ◽  
Zhao Jun Wen ◽  
Xiao Ming Liu ◽  
...  
Keyword(s):  
Internal Structure ◽  
Experimental Research ◽  
Rock Strength ◽  
Drilling Fluid ◽  
Expansion Ratio ◽  
Wellbore Stability ◽  
Test Results ◽  
Fracture Formation ◽  
Set Up ◽  
Activity Window

The crack formed under the action of circular medium fluid around the wellbore of brittle shale has been a hot issue in recent years. This paper considers the brittle shale micro fracture formation mechanism from the perspective of inhibitive ability of drilling fluid activity. The model of activity-swelling-hydration is set up firstly through revising generalized Usher model, it states the drilling fluid activity range to keep wellbore in osmotic hydration stage with the critical expansion ratio, thus puts forward the concept of activity window and is verified by indoor test. Results show that the different activity of drilling fluid brings difference in rock strength in macro and time sensitive effect for internal structure of rock in micro. This mechanism can provide a more accurate range design for drilling fluid activity and strong guarantee for wellbore stability.

Cavitation Testing of Propellers in a Free Surface Tunnel Utilizing Micro Air Bubble Control

1975 ◽  
Vol 97 (4) ◽  
pp. 523-531 ◽  
Author(s):  
K. Albrecht ◽  
O. Bjorheden
Keyword(s):  
Free Surface ◽  
Air Bubbles ◽  
Special Device ◽  
Test Results ◽  
Air Bubble ◽  
Bubble Cavitation ◽  
Marine Laboratory

Cavitation testing in a free surface tunnel presents specific problems in terms of low content of undissolved micro air bubbles in the water owing to the high de-aerating capacity of the tunnel. Such air nuclei are necessary to provide realistic conditions for the inception and extension of cavitation, in particular bubble cavitation at intermediate propeller loading. This paper gives a brief discussion of the problem in relation to some test results obtained in the new free surface tunnel at the KMW Marine Laboratory. A special device built into the tunnel circuit to produce the necessary amount of micro bubbles and its effect on cavitation and propeller forces is described.

scholarly journals PROMINE

PROMINE ◽  
2017 ◽  
Vol 5 (2) ◽  
pp. 42-47
Author(s):  
Delita Ega Andini
Keyword(s):  
Surface Water ◽  
Future Development ◽  
Water Samples ◽  
Field Observation ◽  
Test Results ◽  
Static Test ◽  
Rock Samples ◽  
Al Content ◽  
Surface Water Samples

The condition of water, soil and rock in Bangka Belitung University can be one of reference forconservation area and future development. Field observation known that the research location isgrouped into formation of sedimentary is Tanjung Genting Formation. Average pH of water 5,3; TDS41.1 mg/l; TSS 11,1 mg/l and Al content 0,18 mg/l; Fe 0.32 mg/l; Cu 0.14 mg/l taken from groundwaterand surface water samples. Rock samples of static test results obtained that the rocks are acidic butinto the category is uncertain. However, from the paste pH it was found that the pH of rocks is 5,39and this shows that the rocks are not potentially acidic.

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