scholarly journals Experimental Study on Sand Inrush Hazard of Water-Sand Two-Phase Flow in Broken Rock Mass

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Junce Xu ◽  
Hai Pu ◽  
Jiarui Chen ◽  
Ziheng Sha
Keyword(s):  
Rock Mass ◽  
Western China ◽  
Fracture Aperture ◽  
Exponential Relationship ◽  
Two Phase ◽  
Rock Mass Structure ◽  
Fracture Angle ◽  
Sand Mixture ◽  
Control Factors ◽  
Seepage Characteristics

In the western region of China, coal mining activities are prone to induce water and sand inrush disasters, which seriously threaten the safe production of the coal resources. In this paper, an experimental device was designed to simulate the process of water and sand inrush, and then, the control factors of the disasters in the broken rock mass in the goaf were investigated. Also, the seepage fracture channels in the broken rock mass were simplified by using the 3D printing technology, and the effects of fracture aperture and angle on the seepage characteristics of water-sand mixtures were analyzed. The experimental results showed that the porosity and skeleton structure of the broken rock mass were the key factors to control the water and sand inrush disasters. The smaller the initial porosity of the broken rock mass, the weaker its permeability, and the less probable to form a dominant channel for the water and sand inrush disasters. Conversely, the broken rock mass structure with larger size gradation was more likely to form the permeable channels, and the quality of the sand inrush was greater. In addition, it was also found that the angle of the fractures within the broken rock mass affected the seepage characteristics of water-sand mixture, and the permeability showed an exponential relationship with the fracture angle. Meanwhile, as the fracture aperture increased, the fracture angle generated greater influence on the permeability. Finally, we proposed the water and sand inrush prevention and control technology based on the experiment results. The results of this study can provide a reference for the control of water and sand inrush disasters in western China.

scholarly journals Experimental Study on Water-Sand Seepage Characteristics in Fractured Rock Mass under Rheological Effect

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Jiarui Chen ◽  
Hai Pu ◽  
Jianxiong Liu ◽  
Jihua Zhang ◽  
Peitao Qiu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Rheological Model ◽  
Fractured Rock ◽  
Western China ◽  
Rheological Parameters ◽  
Sand Filtration ◽  
Fractured Rock Mass ◽  
Exponential Relationship ◽  
Rock Samples ◽  
Mixed Fluid

This study investigates water-sand bursting disasters associated with fractured rock that affect safe mining in the mining areas of Western China. A broken rock water-sand seepage rheological test device was developed, and rheological tests were conducted on multiple groups of broken rock samples with single-stage axial loading and different load levels. When the rheology of each group of broken rock samples was stable, water-sand mixed fluid was injected into the samples at a certain pressure gradient to conduct water-sand seepage tests on broken rock masses. It was found that when the porosity of a fractured rock mass is within a certain range, the water-sand mixed fluid does not completely pass through the fractured rock mass and some sand particles are filtered by the fractured rock sample. There is an exponential relationship between the sand breaking ability and the sand filtration ability of fractured rock and its initial porosity, and the permeability of fractured rock decreases by a certain extent after sand filtration. However, for different load levels, when the flow through a fractured rock mass tends to be stable, the final porosity of the fractured rock mass decreases exponentially with axial compression. Based on the classical Kelvin rheological model and the basic theory of fractional calculus, a new fractional rheological model has been proposed and the rheological parameters under different load levels were fitted to the model. The new fractional rheological model is better able to describe the rheological characteristics of broken mudstone.

scholarly journals Seepage Characteristics and Its Control Mechanism of Rock Mass in High-Steep Slopes

Processes ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 71 ◽  
Author(s):  
Hong Li ◽  
Hongyuan Tian ◽  
Ke Ma
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Fractured Rock ◽  
Scientific Progress ◽  
Control Measures ◽  
Cycle Performance ◽  
Fracture Aperture ◽  
Integrated Monitoring ◽  
Seepage Control ◽  
Seepage Characteristics

In Southwest China large-scale hydropower projects, the hydraulic conductivity and fracture aperture within the rock mass of a reservoir bank slope has dramatically undergone a time series of evolution during dam abutment excavation, reservoir impounding and fluctuation operation, and discharge atomization. Accordingly, seepage control measures by hydro-structures such as drainage or water insulation curtains should be guided by scientific foundation with a dynamic process covering life-cycle performance. In this paper, the up-to-date status of studying the evolution mechanism of seepage characteristics relating to fractured rock hydraulics from experimental samples to the engineering scale of the rock mass is reviewed for the first time. Then, the experimental findings and improved practice method on nonlinear seepage flow under intensive pressure drives are introduced. Finally, the scientific progress made in fractured rock seepage control theory and optimization of the design technology of high-steep slope engineering is outlined. The undertaken studies summarized herewith are expected to contribute to laying a foundation to guide the further development of effective geophysical means and integrated monitoring systems in hydropower station construction fields.

scholarly journals Evolution Pattern and Matching Mode of Precursor Information about Water Inrush in a Karst Tunnel

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1579
Author(s):  
Jie Song ◽  
Diyang Chen ◽  
Jing Wang ◽  
Yufeng Bi ◽  
Shang Liu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Stress Field ◽  
Displacement Field ◽  
Water Inrush ◽  
Seepage Field ◽  
Karst Tunnel ◽  
Rock Mass Structure ◽  
Evolution Pattern ◽  
Water Blocking ◽  
Precursor Information

The water inrush of the Shangjiawan karst tunnel is used to study the evolution pattern of precursor water inrush information in water-filled caves and to further reveal the matching mode of the information. The three-dimensional numerical method FLAC3D was used to simulate the evolution process of water inrush after damage to a water-blocking rock mass structure in a water-filled cave and to obtain the evolution pattern of precursor water-inrush information caused by the damage. The results show that the multifield response to the characteristic precursor information of the water-inrush pattern after the fracture of the water-blocking rock mass follows the order of stress-field displacement-field seepage-field. Further, the matching pattern of the information shows that the stress field increased first and then decreased, the displacement field always increased, and the seepage field increased first and then decreased.

Rock mass structure analysis based on seismic velocity and attenuation images

2000 ◽  
Vol 45 (13) ◽  
pp. 1211-1216 ◽  
Author(s):  
Xu Chang ◽  
Yike Liu ◽  
Hui Wang ◽  
Xing Gao
Keyword(s):  
Rock Mass ◽  
Structure Analysis ◽  
Seismic Velocity ◽  
Rock Mass Structure

Modelling Rheological Behavior of Fresh Cement-Sand Mixtures

2014 ◽  
Author(s):  
Hooman Hoornahad ◽  
Eduard A. B. Koenders
Keyword(s):  
Rheological Behavior ◽  
Phase Model ◽  
Single Element ◽  
Void Space ◽  
Two Phase ◽  
Sand Mixture ◽  
Equal Thickness ◽  
Element Interactions

In this paper, the effect of the mix composition on rheological behavior of fresh cement-sand mixture is studied by considering a mixture as a two-phase model that is decomposed into a granular and a paste phase. The paste itself is subdivided into void paste and excess paste. Void paste fills the void space between the grains when they are in a fully compacted state while excess paste will use the remaining paste to form a paste layer around each individual grain particle, with equal thickness. By considering each grain particle covered with the excess paste layer as a single element, the rheological behavior of cement-sand mixtures can be related to their inter-element interactions for all sets of particle combinations.

Evaluation Method for Rock Mass Structure Integrity Based on Borehole Multivariate Data

2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Jinchao Wang ◽  
Hanhua Xu ◽  
Wei Chen ◽  
Chuanying Wang ◽  
Zengqiang Han
Keyword(s):  
Rock Mass ◽  
Evaluation Method ◽  
Multivariate Data ◽  
Rock Mass Structure

Assessment of Weathering Effects on Rock Mass Structure

2014 ◽  
Vol 72 (1) ◽  
Author(s):  
Seyed Vahid Alavi Nezhad Khalil Abad ◽  
Edy Tonnizam Mohamad ◽  
Ibrahim Komoo ◽  
Roohollah Kalatehjari
Keyword(s):  
Rock Mass ◽  
Stereographic Projection ◽  
Granitic Rock ◽  
Rock Mass Structure ◽  
Joint Spacing ◽  
Specific Relation ◽  
Joint Characteristics ◽  
Increasing Trend ◽  
Weathering Effects

This paper presents an assessment of weathering effect to the rock mass structure by studying the joint characteristics of tropically weathered granite. Joint survey was performed by scanline method and the results were analyzed statistically by stereographic projection plots. The overall trend of mean joint spacing followed a sharp decrement from fresh to moderately weathered zone and then a slight increment to highly and completely weathered zones, whereas the overall trend of mean joint trace length showed a gradual decrement over progress of weathering. In addition, the degree of joints inclination and weathering zones revealed an increasing trend in the percentage of horizontal joints from fresh to completely weathered rocks, while no specific relation was found between the numbers of major joint set and different weathering zones. The results of this study may contribute to understanding the behavior and better classification of weathered granitic rock mass as a heterogeneous mass in engineering works.

scholarly journals Prediction Models of Droplet Characteristics Based on the Locally Convergent Configurations in PMMA Microchips

2021 ◽  
Vol 2097 (1) ◽  
pp. 012027
Author(s):  
Zhongxin Liu ◽  
Zhiliang Wang ◽  
Chao Wang ◽  
Jinsong Zhang
Keyword(s):  
Flow Rate ◽  
Relative Position ◽  
Prediction Models ◽  
Continuous Phase ◽  
Lubricating Oil ◽  
Flow Rate Ratio ◽  
Phase Flow ◽  
Exponential Relationship ◽  
Two Phase ◽  
Relationship Of

Abstract This paper novel designed the local convergence configuration in the coaxial channels to study the two-phase flow (lubricating oil (continuous phase, flow rate Q c)/deionized water (dispersed phase, flow rate Q d)). Two geometric control variables, the relative position (x) and tapering characteristics (α), had the different effects on the droplet formation. The increase of relative position x caused the higher frequency and finer droplets, and the increase of convergence angle α, took the opposite effects. The results indicated that the equivalent dimensionless droplet length Ld/Wout and the flow rate ratio Qd/Qc had an exponential relationship of about 1/2. Similarly, it was found that the dispersed droplets generating frequency and the two-phase capillary number, CaTP = uTPμc/σ, had an exponential relationship. The advantage of the convergent configurations in micro-channel was the size and efficiency of droplet generation was very favorable to be controlled by α and x.

Rock mass structure

1999 ◽  
pp. 48-86
Author(s):  
B. H. G. Brady ◽  
E. T. Brown
Keyword(s):  
Rock Mass ◽  
Rock Mass Structure
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