scholarly journals Experimental Investigation on Seepage Stability of Filling Material of Karst Collapse Pillar in Mining Engineering

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Bangyong Yu ◽  
Zhanqing Chen ◽  
Jiangyu Wu
Keyword(s):  
Water Flow ◽  
Water Pressure ◽  
Water Flow Rate ◽  
Test System ◽  
Initial Porosity ◽  
Karst Collapse ◽  
Filling Material ◽  
Karst Collapse Pillar ◽  
Seepage Properties ◽  
Cementing Material

In northern China, groundwater inrush of Karst collapse pillar (KCP) often affects the coal mining process. Current studies rarely consider the seepage stability of filling materials of KCP, especially through experimental investigations. This study is to quantify the impacts of variable initial porosity and cementing strength on the seepage properties of filling material. For this purpose, we designed and fabricated a test system. This system can offer high water pressure and abundant water flow rate. We tested three types of specimens which were cemented by clay, gypsum, and cement, respectively. The seepage properties were obtained under the initial porosity of 0.11, 0.13, 0.15, and 0.17, respectively. The change mechanism of seepage properties was measured through the comparison between mass loss and mass gain. The results showed the followings findings: (1) The permeability-time curves have two types: the first type is that permeability gradually increases up to the occurrence of seepage instability and the second type is that permeability gradually decreases and approaches to a stable value. No seepage instability is observed. (2) Initial porosity and cementing material significantly affect the water flow properties of filling material. In general, larger initial porosity has larger permeability. For clay as cementing material, seepage instability occurs soon and higher initial porosity has shorter time to reach seepage instability. For gypsum, seepage instability occurs after a period of time when initial porosity is large enough. For cement, the permeability decreases gradually and approaches to a stable value. The permeability-time curves have rapid decrease and slow decrease. (3) The permeability has a magnitude of 10−15–10−13 m2 and varies with initial porosity and cementing materials. The permeability is the largest for clay cementing and is the smallest for cement cementing.

scholarly journals Water Discharge Management Based on Open and Closed Cylinders in the Gravitation Water Vortex Power Plant

2021 ◽  
Vol 5 (1) ◽  
pp. 22-36
Author(s):  
Muhammad Hasan Basri ◽  
Ainun Nasuki
Keyword(s):  
Power Plant ◽  
Water Flow ◽  
Flow Rate ◽  
Water Pressure ◽  
Water Discharge ◽  
Water Flow Rate ◽  
Discharge Measurement ◽  
Closed Basin ◽  
Advantages And Disadvantages ◽  
Discharge Management

A Gravitation Water Vortex Power Plant (GWVPP) tool has been made to determine how much water flow is needed to generate electricity. This research was conducted by changing the flow rate and water pressure to determine the effect on the performance of a vortex power plant, and in previous studies, no one has made changes to the discharge and water pressure. The type of basin position used in this study is an open basin position and a closed basin position. Based on the advantages and disadvantages of each type of blade used, a study was carried out using the type of turbine blade model L by changing the water flow rate and water pressure at a predetermined position to determine the effect of water discharge and pressure on the turbine rotational speed. From the results of testing the water discharge measurement in a closed basin which is carried out on the addition of each flow of water discharge at the angle of the faucet 0o to 90o with a volume (V) 98 L and time (t) 1.11 minutes to 2.5 minutes, it can be seen that the average discharge value (Q) the resulting 81.08 l / s. and from the results of testing the water discharge measurement in the open basin which is carried out to the addition of each flow of water discharge at the angle of the faucet 0o to 90o with a volume (V) 98 L and time (t) 1.28 minutes to 4.1 minutes it can be seen that the average discharge value (Q ) resulting in 65.21 l / s.

scholarly journals Experimental Study of Pore Permeability Characteristics Based On Variable-Mass System In Karst Collapse Pillars

2022 ◽  
Author(s):  
Mingkun Pang ◽  
Tianjun Zhang ◽  
Rongtao Liu ◽  
Haotian Wang
Keyword(s):  
Pore Structure ◽  
Fine Particles ◽  
Structural Characteristics ◽  
Water Pressure ◽  
Variable Mass ◽  
Test System ◽  
Crushed Rock ◽  
Karst Collapse ◽  
Mass System ◽  
Particle Loss

Abstract Particle loss is the root cause for the occurrence of Karst Collapse Pillars (KCP) sudden water events. The pore adjustment of KCP filler will further induce seepage destabilization, and it is also a process that sudden water catastrophe must go through. In order to investigate the direct relationship between stress conditions, water pressure conditions, and gradation structure on the pore structure of rock samples, the steady-state percolation method was used to investigate the percolation test system of variable-mass crushed rock masses. The results show that: 1) the structural characteristics of rock grains under the same stress environment are closely related to their extrusion fragmentation process and the softening and scouring effect of water. Rubbing, rotating, fracturing, grinding and plugging are the main forms of action of their intergranular action. 2) The filling particles before and after the loss meet the fractal law and have fractal characteristics. 3) The percentage of fine particles in the whole process of infiltration loss is as high as 34.4%. The adjustment of pore structure is related to the particle size gradation, and the reciprocal action of water flow will form a stable water-conducting channel. 4) The sudden water process of the specimen under particle loss can be divided into three stages: initial seepage, catastrophic destabilization and pipe flow surge.

scholarly journals SMART WATER NETWORK MONITORING: A CASE STUDY AT UNIVERSITI TEKNOLOGI MALAYSIA

2022 ◽  
Vol XLVI-4/W3-2021 ◽  
pp. 3-7
Author(s):  
N. A. A. Abdul Aziz ◽  
T. A. Musa ◽  
I. A. Musliman ◽  
A. H. Omar ◽  
W. A. Wan Aris
Keyword(s):  
Real Time ◽  
Water Flow ◽  
Water Pressure ◽  
Water Flow Rate ◽  
Water Monitoring ◽  
Geographical Information ◽  
Smart Water ◽  
Cloud Computing Service ◽  
Water Measurement ◽  
Water Uses

Abstract. Water uses need to be measured, which is critical for evaluating water stress. The Industry 4.0 via the Internet of Things (IoT) and usage of water measurement sensor can provide real-time information on the water flow rate and water pressure, that is crucial for water monitoring and analysis. There is a need for online smart water monitoring that gives out more efficient and sustainable water uses at Universiti Teknologi Malaysia (UTM) campus. A prototype of an online smart water monitoring for UTM, which was developed based on the integration of IoT and Geographical Information System (GIS), consist of four layers; (1) physical layer; (2) network layer; (3) processing layer and, (4) application layer. The findings show that when the water flow increases, the water pressure decreases. When there is no water flow, the lowest value is 52.214 Psi, and the highest value is 60.916 Psi. The latest technology integrating the IoT-GIS for smart water monitoring has shown a very efficient way of providing real-time water parameters information, cost and time effective, and allowing for continuous water consumption analysis via the cloud computing service.

scholarly journals Experimental Study on the Failure Mechanism of Tunnel Surrounding Rock under Different Groundwater Seepage Paths

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Yingchao Wang ◽  
Yang Liu ◽  
Yongliang Li ◽  
Wen Jiang ◽  
Yueming Wang
Keyword(s):  
Failure Mechanism ◽  
Water Flow ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Water Flow Rate ◽  
Surrounding Rock ◽  
Tunnel Engineering ◽  
Measuring Point ◽  
Groundwater Seepage

The influence of groundwater on tunnel engineering is very complicated. Due to the complexity of water flow water pressure transfer and uncertain defects in the stratum, all of which are key factors with regard to the design of tunnel engineering. Therefore, the variation of surrounding rock during excavation and the deformation and failure of soft surrounding rock under different seepage paths of underground water after excavation systematically. Experimental results showed that the stress change of surrounding rock caused by tunnel excavation can be divided into 3 stages: stress redistribution, stress adjustment, and stress rebalancing. In the process of water pressure loading, water flow rate is closely related to the experimental phenomenon. The between stable loading water pressure pore water pressure of the tunnel surrounding rock and the distance from the measuring point to the edge of the tunnel obey the exponential function of the decreasing growth gradient. With the increase of loading pressure, the pore water pressure and stress at the top of the tunnel increase, and the coupling of stress field and seepage field on both sides of surrounding rock more and more intense. The failure process of the tunnel can be divided into 6 stages according to the damage degree. The final failure pattern of the surrounding rock of the tunnel is mainly determined by the disturbed area of excavation. The arched failure area and the collapse-through failure area are composed of three regions. The surrounding rock is characterized by a dynamic pressure arch in the process of seepage failure, but it is more prone to collapse failure at low water pressure. The results of this study are the progressive failure mechanism of tunnel under different groundwater seepage paths and would be of great significance to the prevention of long-range disasters.

scholarly journals Evolution Model of Seepage Characteristics in the Process of Water Inrush in Faults

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Jianli Shao ◽  
Fei Zhou ◽  
Wenbin Sun
Keyword(s):  
Water Flow ◽  
Water Pressure ◽  
Water Inrush ◽  
Water Flow Rate ◽  
Initial Permeability ◽  
Effective Porosity ◽  
Evolution Model ◽  
Particle Migration ◽  
Evolution Process ◽  
Seepage Characteristics

Although the mechanism and influence of fault water inrush have been widely studied, there are still few studies on the migration of filling particles and the evolution process of seepage characteristics within faults. In this work, the coupling effects of water flow, particle migration, and permeability evolution are considered synthetically, and the evolution model of seepage characteristics with multifield coupling is established. This model was used to investigate the evolution process of water inrush within faults and the effects of water pressure, initial effective porosity, and initial permeability on water flow rate. The results show that the evolution of seepage characteristics can be divided into three phases: (i) low velocity seepage, (ii) drastic changes with substantial particle migration, and (iii) steady-state water flow. The multifield coupling causes the effective porosity, permeability, flow velocity, and particle concentration to accelerate each other during the dramatic phase. Moreover, the increases in initial water pressure, initial porosity, and initial permeability have different degrees of promotion on the water flow rate. Finally, the simulation results are approximately the same as the data of water inrush in the mining area, which verifies the correctness of the evolution model established in this work. This work provides new approaches to the evolution process and prevention of water inrush in faults.

scholarly journals Predicting Erosion-Induced Water Inrush of Karst Collapse Pillars Using Inverse Velocity Theory

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Banghua Yao ◽  
Zhongwei Chen ◽  
Jianping Wei ◽  
Tianhang Bai ◽  
Shumin Liu
Keyword(s):  
Water Flow ◽  
Water Pressure ◽  
Water Inrush ◽  
Karst Collapse ◽  
Power Relationship ◽  
Exponential Relationship ◽  
Fracture Geometry ◽  
Rock Heterogeneity ◽  
The Impact ◽  
Inverse Velocity

Although the impact of Karst Collapse Pillars (KCPs) on water inrush has been widely recognized and studied, few have investigated the fluid-solid interaction, the particles migration inside KCPs, and the evolution feature of water inrush channels. Moreover, an effective approach to reliably predict the water inrush time has yet to be developed. In this work, a suite of fully coupled governing equations considering the processes of water flow, fracture erosion, and the change of rock permeability due to erosion were presented. The inverse velocity theory was then introduced to predict the water inrush time under different geological and flow conditions. The impact of four different controlling factors on the fracture geometry change, water flow, and inrush time was discussed in detail. The results showed that the inverse velocity theory was capable of predicting the occurrences of water inrush under different conditions, and the time of water inrush had a power relationship with the rock heterogeneity, water pressure, and initial particle concentration and an exponential relationship with the initial fracture apertures. The general approach developed in this work can be extended to other engineering applications such as the tunneling and tailing dam erosion.

Flow Erosion Resistance of Concrete - Interaction of High-Speed Water Jet and Concrete

2019 ◽  
Vol 296 ◽  
pp. 215-220
Author(s):  
Lenka Bodnárová ◽  
Rudolf Hela ◽  
Libor Sitek ◽  
Petr Hlaváček ◽  
Josef Foldyna
Keyword(s):  
Water Flow ◽  
High Speed ◽  
Water Pressure ◽  
Water Flow Rate ◽  
Concrete Surface ◽  
Water Jet ◽  
Cement Matrix ◽  
Polypropylene Fibres ◽  
Steel Fibres ◽  
Erosive Effect

In the paper, the resistance of concrete to the erosive effect of water from a water jet was monitored. The tests were performed on concrete without the addition of fibres and on concrete with the addition of polypropylene fibres and steel fibres. The water flow hit the concrete surface at an angle of 90°. The water flow rate was 1.1 l/min and the water pressure was 80 MPa. After blasting the concrete with water jet, no cracks in the concrete were observed and the intended rugged surface relief was created. Steel fibres remained firmly anchored into the cement matrix.

Experimental Study on Thermal Characteristics of Finned Coil LHSU Using Paraffin as Phase Change Material

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Guansheng Chen ◽  
Nanshuo Li ◽  
Huanhuan Xiang ◽  
Fan Li
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Phase Change ◽  
Phase Change Material ◽  
Water Flow ◽  
Water Flow Rate ◽  
Thermal Characteristics ◽  
Heat Transfer Fluid ◽  
Latent Heat Storage ◽  
Change Material

It is well known that attaching fins on the tubes surfaces can enhance the heat transfer into and out from the phase change materials (PCMs). This paper presents the results of an experimental study on the thermal characteristics of finned coil latent heat storage unit (LHSU) using paraffin as the phase change material (PCM). The paraffin LHSU is a rectangular cube consists of continuous horizontal multibended tubes attached vertical fins at the pitches of 2.5, 5.0, and 7.5 mm that creates the heat transfer surface. The shell side along with the space around the tubes and fins is filled with the material RT54 allocated to store energy of water, which flows inside the tubes as heat transfer fluid (HTF). The measurement is carried out under four different water flow rates: 1.01, 1.30, 1.50, and 1.70 L/min in the charging and discharging process, respectively. The temperature of paraffin and water, charging and discharging wattage, and heat transfer coefficient are plotted in relation to the working time and water flow rate.

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