scholarly journals Analysis and Application of the Mechanical Properties of the Karst Collapse Column Fillings

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Zhibin Lin ◽  
Boyang Zhang ◽  
Xiaofei Gong ◽  
Limin Sun ◽  
Wenzhen Wang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Moisture Content ◽  
Water Inrush ◽  
Friction Angle ◽  
Karst Collapse ◽  
Filling Material ◽  
Cohesive Stress ◽  
Consolidation Pressure ◽  
Collapse Column

The filling material of the karst collapse column (KCC) is easy to be activated by mining. During this process, the mechanical properties of KCC fillings change, and its water resisting capacity constantly deteriorates and thus often leads to water inrush disaster. In this study, the samples of KCC fillings were taken on-site and then were remolded by the consolidation drainage method. The variation laws of the compressive strength, tensile strength, cohesive stress, internal friction angle, and permeability of the filling samples with respect to the consolidation pressure and moisture content were tested and analyzed. Based on an engineering example, the yield and activation and particle loss of the filling material of the KCC are analyzed. A mechanism for the lagging water inrush of KCC in the process of mining is proposed. The main results of the present study can be concluded concisely as follows. (1) The KCC fillings show obvious soft rock characteristics in the process of uniaxial compression and Brazilian split. The ratio of the uniaxial compressive strength to splitting tensile strength is between 12 : 1 and 8 : 1. The larger the consolidation pressure or the smaller the moisture content, the larger the ratio. (2) With the increase of consolidation pressure or the decrease of moisture content, the uniaxial compressive strength, elastic modulus, splitting tensile strength, cohesive stress, and internal friction angle of the filling material of the KCC increase linearly, while its permeability increases exponentially. (3) When the crack field of the surrounding rocks of the stope is connected with the KCC, its filling material will continue to yield, activate, and migrate under the fluid-solid coupling effect and finally result in the lagging water inrush from the KCC.

scholarly journals AN INVESTIGATION ON THE EFFECTS OF MICRO-PARAMETERS ON THE STRENGTH PROPERTIES OF ROCK

2021 ◽  
Vol 36 (1) ◽  
pp. 111-119
Author(s):  
Behzad Jafari Mohammadabadi ◽  
Kourosh Shahriar ◽  
Hossein Jalalifar ◽  
Kaveh Ahangari
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Friction Coefficient ◽  
Critical Stress ◽  
Friction Angle ◽  
Strength Properties ◽  
Brazilian Tensile Strength ◽  
The Relationship

Rocks are formed from particles and the interaction between those particles controls the behaviour of a rock’s mechanical properties. Since it is very important to conduct extensive studies about the relationship between the micro-parameters and macro-parameters of rock, this paper investigates the effects of some micro-parameters on strength properties and the behaviour of cracks in rock. This is carried out by using numerical simulation of an extensive series of Uniaxial Compressive Strength (UCS) and Brazilian Tensile Strength (BTS) tests. The micro-parameters included the particles’ contact modulus, the contact stiff ness ratio, bond cohesion, bond tensile strength, the friction coefficient and the friction angle, and the mechanical properties of chromite rock have been considered as base values of the investigation. Based on the obtained results, it was found that the most important micro-parameters on the behaviour of rock in the compressive state are bond cohesion, bond tensile strength, and the friction coefficient. Also, the bond tensile strength showed the largest effect under tensile conditions. The micro-parameter of bond tensile strength increased the rock tensile strength (up to 5 times), minimized destructive cracks and increased the corresponding strain (almost 2.5 times) during critical stress.

Study of Correlation on Unconfined Compressive Strength between Different Soil

2013 ◽  
Vol 838-841 ◽  
pp. 926-929
Author(s):  
Xia Zhao
Keyword(s):  
Compressive Strength ◽  
Soil Moisture ◽  
Moisture Content ◽  
Unconfined Compressive Strength ◽  
Laboratory Tests ◽  
Soil Moisture Content ◽  
Correlation Coefficients ◽  
Friction Angle ◽  
Silty Clay ◽  
Soil Cohesion

Take the silty clay and clay as the research object, the correlation between bulk density, moisture content, cohesion, friction angle and unconfined compressive strength was analyzed using laboratory tests, and the results showed that soil cohesion, friction angle and unconfined compressive strength with good correlation, the correlation coefficients were all above 0.9, while severe and soil moisture content and unconfined compressive strength of correlation is weak, followed by the correlation formulas of the index and unconfined compressive strength were established, these formulas can used to predict the unconfined compressive strength of soil.

Strength and Elastic Properties of Cassava Tuber

2007 ◽  
Vol 3 (5) ◽  
Author(s):  
Oladele Peter Kolawole ◽  
Leo Ayodeji Sunday Agbetoye ◽  
A. S. Ogunlowo
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Moisture Content ◽  
Elastic Properties ◽  
Engineering Properties ◽  
Under Five ◽  
Moisture Contents ◽  
Spring Balance

In this study, some engineering properties of cassava tuber samples were determined experimentally under five moisture content levels of 70 %, 65 %, 60%, 55 %, and 50 %wet basis. The properties measured were tensile strength, compressive strength and elasticity. Three experimental tools were designed and fabricated using spring balance, hose-clips, and 12Volts motor with reels and rope for the investigations. The IITA improved cassava variety TMS 4(2) 1425 was used in the experiments. Results of the tests indicated that all the properties measured were influenced by the moisture contents of the tuber.

scholarly journals Modelling igneous rock mechanics parameter based on logging data in Shunbei oil field

2021 ◽  
Vol 2076 (1) ◽  
pp. 012008
Author(s):  
Wenxia Li ◽  
Weiqiang Song ◽  
Jingtao Liu ◽  
Xiuping Chen ◽  
Huidong Mu
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Rock Mechanics ◽  
Igneous Rock ◽  
Friction Angle ◽  
Rock Breaking ◽  
Oil Field ◽  
Rate Of Penetration ◽  
The North ◽  
Rock Strata

Abstract In order to improve the rate of penetration (ROP) in Permian igneous rock strata, the rock mechanics is modeled based on the continuous logging data (acoustic, density, caliper, resistivity and gamma logging) and confirmatory indoor experiments. The model considers the influence of well collapse and expansion on logging data in igneous rock formation to improve the calculation accuracy. Based on this model, the continuous profile of Permian compressive strength, tensile strength, mud content, internal friction angle are calculated, and then the differences of Permian strata in the north, middle and south of the oilfield are further compared and analyzed. The results can provide support for the optimization of efficient rock breaking and reservoir fracturing technology.

scholarly journals A non-linear flow model for the flow behavior of water inrush induced by the karst collapse column

RSC Advances ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 1656-1665 ◽  
Author(s):  
Xian'gang Hou ◽  
Wenhao Shi ◽  
Tianhong Yang
Keyword(s):  
Flow Model ◽  
Flow Behavior ◽  
Water Inrush ◽  
Karst Collapse ◽  
Flow Transition ◽  
Linear Flow ◽  
Non Linear ◽  
Collapse Column

A non-linear flow model that couples three flow types is built based on flow transition to investigate the flow behavior of water inrush induced by KCC.

scholarly journals Modeling Rock Fracture Propagation and Water Inrush Mechanisms in Underground Coal Mine

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Shichuan Zhang ◽  
Baotang Shen ◽  
Yangyang Li ◽  
Shengfan Zhou
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Rock Fracture ◽  
Water Inrush ◽  
Water Channel ◽  
Karst Collapse ◽  
Mining Equipment ◽  
Geological Conditions ◽  
Fracturing Process ◽  
Collapse Column

Water inrush in underground mines is a major safety threat for mining personnel, and it can also cause major damage to mining equipment and result in severe production losses. Water inrush can be attributed to the coalescence of rock fractures and the formation of water channel in rock mass due to the interaction of fractures, hydraulic flow, and stress field. Hence, predicting the fracturing process is the key for investigating the water inrush mechanisms for safe mining. A new coupling method is designed in FRACOD to investigate the mechanisms of water inrush disaster (known as “Luotuoshan accident”) which occurred in China in 2010 in which 32 people died. In order to investigate the evolution processes and mechanisms of water inrush accident in Luotuoshan coal mine, this study applies the recently developed fracture-hydraulic (F-H) flow coupling function to FRACOD and focuses on the rock fracturing processes in a karst collapse column which is a geologically altered zone linking several rock strata vertically formed by the long-term dissolution of the flowing groundwater. The numerical simulation of water inrush is conducted based on the actual geological conditions of Luotuoshan mining area, and various materials with actual geological characteristics were used to simulate the rocks surrounding the coal seam. The influences of several key factors, such as in situ stresses, fractures on the formation, and development of water inrush channels, are investigated. The results indicate that the water inrush source is the Ordovician limestone aquifer, which is connected by the karst collapse column to No. 16 coal seam; the fracturing zone that led to a water inrush occurs in front of the roadway excavation face where new fractures coalesced with the main fractured zone in the karst collapse column.

Tensile Strength of Concrete at Different Strain Rates

1985 ◽  
Vol 64 ◽  
Author(s):  
Parviz Soroushian ◽  
Ki-Bong Choi ◽  
Gung Fu
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Moisture Content ◽  
Strain Rate ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Direct Tension ◽  
Dynamic Tensile Strength ◽  
Strength Tests ◽  
Compressive Strength Of Concrete

ABSTRACTResults of dynamic tensile strength tests of concrete, produced by the authors and other investigators, were used to study the effects of strain rate on the tensile strength of concrete. The influence of moisture content and compressive strength of concrete, and type of test (splitting tension, flexure, or direct tension) on the strain rate-sensitivity of the tensile strength were evaluated. An empirically developed expression is presented for the dynamic-to-static ratio of concrete tensile strength in terms of the rate of straining.

scholarly journals PANEL DINDING GEOPOLIMER DENGAN PERKUATAN WIREMESH

2020 ◽  
Vol 16 (1) ◽  
pp. 13-23
Author(s):  
Andini Pratiwi Putri ◽  
Iman Satyarno ◽  
Ashar Saputra
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Sulfuric Acid ◽  
Fly Ash ◽  
Environmentally Friendly ◽  
High Hardness ◽  
Filling Material ◽  
Acidic Environment ◽  
Heat Temperature ◽  
Wall Panels

ABSTRAK Pengembangan fly ash berbasis geopolimer sangat cocok untuk memperluas aplikasi pracetak khususnya panel dinding pada lingkungan asam sulfat. Panel berbahan abu terbang ini dapat dijadikan pertimbangan karena memiliki keunggulan diantaranya kekerasan tinggi, ramah lingkungan, tidak menghasilkan gas karbon (CO2), tahan pada temperatur panas antara 600-800° C, tahan lingkungan asam, dan tidak memerlukan perawatan panas. Untuk pembuatan struktur panel pracetak menggunakan bahan pengisi berupa mortar berbahan geopolimer dengan komposisi NaOH 14 M, rasio NaOH/Na2SiO3 sebesar 1 :2, rasio alkaline : fly ash sebesar 35%, dan menggunakan variasi wiremesh sebagai perkuatan, dengan ukuran benda uji panel 800x400x40 mm. Hasil yang didapat kuat tekan umur 1 hari sebesar 11.27 MPa umur 28 hari 60,84 MPa, dengan nilai modulus 28 hari sebesar 13808 MPa. Pengujian kuat tarik 1 hari sebesar 1.02 MPa dan 28 hari sebesar 2,95 MPa Pengujian kuat lentur didapatkan 3,52 MPa tanpa perkuatan dan 4,52 dengan perkuatan. Kata kunci: Geopolymer, panel, wiremesh  ABSTRACT Geopolymer-based fly ash development is perfect for expanding precast applications especially wall panels in sulfuric acid environments. Panels made of fly ash can be considered because it has the advantage of high hardness, environmentally friendly, does not produce carbon gas (CO2), resistant to heat temperature between 600-800 ° C, resistant to acidic environment, and not require hot maintenance.To create the structure of precast panels using mortar filling material with geopolymer with composition NaOH 14 M, ratio of NaOH/Na2SiO3 is 1:2, ratio alkaline ratio: fly ash 35%, and use wiremesh variation, size of panel 800x400x40 mm. Results obtained compressive strength of 1 day 11.27 MPa, age 28 Days 60.84 MPa, modulus elasticity 28-day 13808 MPa. Result tensile strength 1-day 1.02 MPa and 28 days 2.95 MPa, frexural strength panel 3.52 MPa without wiremesh and 4.52 with wiremesh. Keywords: Geopolymer, panels, wiremesh

scholarly journals Evolution Mechanism of Water-Conducting Channel of Collapse Column in Karst Mining Area of Southwest China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zhengzheng Cao ◽  
Yulou Ren ◽  
Qinting Wang ◽  
Banghua Yao ◽  
Xinchao Zhang
Keyword(s):  
Coal Seam ◽  
Southwest China ◽  
Water Inrush ◽  
Mining Area ◽  
Karst Collapse ◽  
Coal Field ◽  
Conducting Channel ◽  
Evolution Mechanism ◽  
Working Face ◽  
Collapse Column

There are many karst collapse columns in coal seam roof in the southern coal field in China, which are different from those in coal seam floor in the northern coal field, due to the stratum characteristics. The karst collapse column in coal seam roof tends to reactivate and conduct water and induce the serious water inrush disaster, when the karst collapse column communicates with the overlying aquifer. In order to reveal the evolution mechanism of water-conducting channel of collapse column in karst mining area of southwest China, the aquifers and water inflow rule in 1908 working face in Qianjin coal mine are analyzed. Besides, the particle size distribution and mineral component of collapse column are researched by the X-ray diffraction test and the screening method, which are the basis for researching the water inrush mechanism in karst collapse column. On this basis, the water inrush of roof collapse column under the influence of mining is researched by establishing the numerical calculation model with the UDEC numerical software. The results show that the water flowing into the 1908 working face comes from the Changxing formation aquifer and Yulongshan formation aquifer above the coal seam, and the proportion of coarse particles and fine particles in collapse column is 89.86% and 10.14%, respectively. With the advance of working face, the water-conducting channel connected the working face with the aquifer, or the surface is formed by collapse pits, karst caves, and collapse column. The research results can be treated as an important basis for the water-preserved mining in southern coal field in China.

scholarly journals Seepage Property of Crushed Mudstone Rock in Collapse Column

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Bo-Yang Zhang ◽  
Zhi-Bin Lin
Keyword(s):  
Particle Size ◽  
Water Resource ◽  
Water Inrush ◽  
Underground Water ◽  
Economic Losses ◽  
Karst Collapse ◽  
Hydraulic Pressure ◽  
Water Flow Velocity ◽  
Collapse Column ◽  
Seepage Properties

The karst collapse column composed of crushed rocks and fine argillaceous or clay particles is easy to form the fissure channels between the coal seam working face and the confined limestone aquifer under mining and causes water inrush disasters with the loss of underground water resource, economic losses, and casualties. It is of great necessity to understand the seepage properties of crushed rock in karst collapse column for the prevention of water inrush and the protection of underground water resource. A self-developed seepage test system is used in this paper to conduct laboratory experiments on seepage properties of crushed mudstone specimens. The effects of the particle size distribution, the porosity (specimen height), and the hydraulic pressure on the water flow velocity and the permeability of crushed specimen are analyzed. The results indicate that the permeability of specimen increases with the particle size, porosity, and hydraulic pressure. It can be known from the comparative experiments of progressive hydraulic pressure on one specimen and variable hydraulic pressure on different specimens with constant particle size and porosity that more fine particles leak out from the specimen with repeated application of hydraulic pressure on one specimen. Therefore, the permeability of one specimen is bigger than that of different specimens under the condition of same hydraulic pressure.

Sign in / Sign up

Export Citation Format

Share Document