Unsteady Seepage Through Random Fracture Network in Rock Mass

2010 ◽  
pp. 31-37
Author(s):  
Junrui CHAI ◽  
Yang HE ◽  
Kanghong LI
Keyword(s):  
Rock Mass ◽  
Fracture Network ◽  
Random Fracture

scholarly journals A methodology of re-generating a representative element volume of fractured rock mass

2020 ◽  
Vol 71 (4) ◽  
pp. 347-358
Author(s):  
DANG Hong-Lam ◽  
THINH Phi Hong
Keyword(s):  
Rock Mass ◽  
Fractured Rock ◽  
Fracture Network ◽  
Hydraulic Calculation ◽  
Fractured Rock Mass ◽  
Fracture Characteristics ◽  
Mechanical Calculation ◽  
Representative Element ◽  
Representative Element Volume ◽  
Actual Fracture

In simulation of fractured rock mass such as mechanical calculation, hydraulic calculation or coupled hydro-mechanical calculation, the representative element volume of fractured rock mass in the simulating code is very important and give the success of simulation works. The difficulties of how to make a representative element volume are come from the numerous fractures distributed in different orientation, length, location of the actual fracture network. Based on study of fracture characteristics of some fractured sites in the world, the paper presented some main items concerning to the fracture properties. A methodology of re-generating a representative element volume of fractured rock mass by DEAL.II code was presented in this paper. Finally, some applications were introduced to highlight the performance as well as efficiency of this methodology.

scholarly journals Flow characteristics of fractal fracture with different fractal dimension and different fracture width

2021 ◽  
Vol 25 (6 Part B) ◽  
pp. 4477-4484
Author(s):  
Jun-Jun Liu ◽  
Jing Xie ◽  
Yi-Ting Liu ◽  
Gui-Kang Liu ◽  
Rui-Feng Tang ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Rock Mass ◽  
Flow Characteristics ◽  
Fracture Network ◽  
Basic Element ◽  
Single Fracture ◽  
Flow State ◽  
Complex Flow ◽  
Fracture Width ◽  
Fracture Models

Single fracture is the most basic element in complex fracture network of rock mass. Therefore, the study of flow characteristics of single fracture is an important way to reasonably predict the complex flow state in engineering rock mass. In order to study the flow characteristics of fractal single fracture, fracture models with dif?ferent fractal dimension and different fracture width are established in this paper. The results show that: the blocking effect of rough structure on fluid is obviously enhanced under high pressure. In addition, it is weakened and reaches a steady-state with the increase of fracture fractal dimension. The larger the fracture width is, the more obvious the phenomenon is. The hydraulic gradient index tends to 0.5 with the increase of fracture width when fractal dimension is greater than 1.3. It also could tend to 0.5 with the increase of fractal dimension when fracture width is greater than 1 mm.

3-D fracture network dynamic simulation based on error analysis in rock mass of dam foundation

2018 ◽  
Vol 25 (4) ◽  
pp. 919-935 ◽  
Author(s):  
Deng-hua Zhong ◽  
Han Wu ◽  
Bin-ping Wu ◽  
Yi-chi Zhang ◽  
Pan Yue
Keyword(s):  
Rock Mass ◽  
Error Analysis ◽  
Dynamic Simulation ◽  
Fracture Network ◽  
Network Dynamic ◽  
Dam Foundation ◽  
Simulation Based

Analysis of Coupled Three-Dimensional Seepage and Temperature Fields in Fracture Network of Rock Mass

2019 ◽  
Vol 17 (04) ◽  
pp. 1950005 ◽  
Author(s):  
Zengguang Xu ◽  
Yang Liu ◽  
Yaping Wang ◽  
Junrui Chai ◽  
Yanlong Li
Keyword(s):  
Rock Mass ◽  
Coupling Effect ◽  
Fractured Rock ◽  
Seepage Flow ◽  
Fracture Network ◽  
Temperature Fields ◽  
Fractured Rock Mass ◽  
Flow Temperature ◽  
Geothermal Resources ◽  
Mass Temperature

The coupling effect of seepage and temperature fields in fractured rock mass is a hot topic in the area of water conservancy, nuclear waste disposal and geothermal resources development. A coupling mathematical model of the seepage, flow temperature and rock mass temperature fields in the fracture network of rock mass is established based on the seepage and temperature interaction. A calculation program is developed and applied to calculate the seepage and temperature fields of the dam foundation of a water conservancy project. The interaction mechanism of the seepage, flow temperature and rock mass temperature fields is analyzed in this paper. Results show that the seepage field largely influences the temperature field, which can provide several suggestions for the deep underground disposal of nuclear waste, geothermal resources development and fractured rock mass in dam foundations. Considering the coupling effect of the seepage, flow temperature and rock mass temperature fields by the fracture network method is necessary.

Construction of 3D Discrete Fracture Network Model using Structural and Hydrogeological Data

2020 ◽  
Author(s):  
Mohammadreza Jalali ◽  
Zhen Fang ◽  
Pooya Hamdi
Keyword(s):  
Rock Mass ◽  
Network Model ◽  
Fracture Network ◽  
Crystalline Rock ◽  
Discrete Fracture Network ◽  
Seismic Survey ◽  
Discrete Fracture ◽  
Dfn Model ◽  
Hydrogeological Data

<p>The presence of fractures and discontinuities in the intact rock affects the hydraulic, thermal, chemical and mechanical behavior of the underground structures. Various techniques have been developed to provide information on the spatial distribution of these complex features. LIDAR, for instance, could provide a 2D fracture network model of the outcrop, Geophysical borehole logs such as OPTV and ATV can be used to investigate 1D geometrical data (i.e. dip and dip direction, aperture) of the intersected fractures, and seismic survey can mainly offer a large structure distribution of the deep structures. The ability to combine all the existing data collected from various resources and different scales to construct a 3D discrete fracture network (DFN) model of the rock mass allows to adequately represent the physical behavior of the interested subsurface structure.</p><p>In this study, an effort on the construction of such a 3D DFN model is carried out via combination of various structural and hydrogeological data collected in fractured crystalline rock. During the pre-characterization phase of the In-situ Stimulation and Circulation (ISC) experiment [Amann et al., 2018] at the Grimsel Test Site (GTS) in central Switzerland, a comprehensive characterization campaign was carried out to better understand the hydromechanical characteristics of the existing structures. The collected multiscale and multidisciplinary data such as OPTV, ATV, hydraulic packer testing and solute tracer tests [Jalali et al., 2018; Krietsch et al., 2018] are combined, analyzed and interpreted to form a combined stochastic and deterministic DFN model using the FracMan software [Golder Associates, 2017]. For further validation of the model, the results from in-situ hydraulic tests are used to compare the simulated and measured hydraulic responses, allowing to evaluate whether the simulated model could reasonably represent the characteristics of the fracture network in the ISC experiment.</p><p> </p><p><strong>References</strong></p><ul><li>Amann, F., Gischig, V., Evans, K., Doetsch, J., Jalali, M., Valley, B., Krietsch, H., Dutler, N., Villiger, L., Brixel, B., Klepikova, M., Kittilä, A., Madonna, C., Wiemer, S., Saar, M.O., Loew, S., Driesner, T., Maurer, H., Giardini, D., 2018. The seismo-hydromechanical behavior during deep geothermal reservoir stimulations: open questions tackled in a decameter-scale in situ stimulation experiment. Solid Earth 9, 115–137.</li> <li>Golder Associates, 2017. FracMan User Documentation.  Golder Associates Inc, Redmond WA.</li> <li>Krietsch, H., Doetsch, J., Dutler, N., Jalali, M., Gischig, V., Loew, S., Amann, F., 2018. Comprehensive geological dataset describing a crystalline rock mass for hydraulic stimulation experiments. Scientific Data 5, 180269.</li> <li>Jalali, M., Klepikova, M., Doetsch, J., Krietsch, H., Brixel, B., Dutler, N., Gischig, V., Amann, F., 2018. A Multi-Scale Approach to Identify and Characterize the Preferential Flow Paths of a Fractured Crystalline Rock. Presented at the 2<sup>nd</sup> International Discrete Fracture Network Engineering Conference, American Rock Mechanics Association.</li> </ul>

A New Method to Determining the Strength Parameters of Fractured Rock Mass

2014 ◽  
Vol 898 ◽  
pp. 378-382
Author(s):  
Yun Hua Guo ◽  
Wei Shen Zhu
Keyword(s):  
Rock Mass ◽  
Mechanical Response ◽  
Fractured Rock ◽  
Fracture Network ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Constitutive Relationship ◽  
Hydropower Station ◽  
Rock Masses ◽  
Fractured Rock Mass

A Hydropower Station is located in the middle reach of the Dadu River in southwest China. The natural slope angles are generally 40°~65° and the relative elevation drop is more than 600m. Complex different fractures such as faults, dykes and dense fracture zones due to unloading are developed. Many abutment slopes were formed during construction of the abutments. The stability of these steep and high slopes during construction and operation period plays an important role for the safe construction and operation of the hydropower station. According to the statistical distribution of joints and fractures at the construction site, the slope is divided into a number of engineering geological zones. For each zone, a stochastic fracture network and a numerical model which is close to the real state of the fractured rock mass are established by the Monte-Carlo method. The mechanical response of fractured rock masses with different sizes of numerical models is studied using FLAC3D. The REV characteristic scale is identified for rock masses in the slopes with stochastic fracture network. Numerical simulation is performed to obtain the stress-strain curve, the mechanical parameters and the strength of the jointed rock mass in the zone. A constitutive relationship reflecting the mechanical response of the jointed rock mass in the zone is established. The Comparison between the traditional method and the method in this paper has been made at the end.

scholarly journals Modelling the variation in the behaviour of pre-fractured rocks subjected to hydraulic fracturing with permeability of the rock matrix using finite-discrete element method

2020 ◽  
Vol 205 ◽  
pp. 08001
Author(s):  
Shahrzad Roshankhah ◽  
Arman K. Nejad ◽  
Orlando Teran ◽  
Kami Mohammadi
Keyword(s):  
Rock Mass ◽  
Finite Elements ◽  
Hydraulic Fracturing ◽  
Discrete Element Method ◽  
Fractured Rocks ◽  
Discrete Element ◽  
Fracture Network ◽  
Rock Matrix ◽  
Flow Through ◽  
Element Method

In this study, we present the results of two-dimensional numerical simulations for the effects of rock matrix permeability on the behaviour of hydraulic fractures in intact and pre-fractured rocks. The simulations are performed using the Finite-Discrete Element Method (FDEM). In this method, the deformation and fluid pressure fields within the porous rock blocks, pre-existing fracture network, and hydraulically induced fractures are calculated through a fully coupled hydromechanical scheme. Furthermore, new fractures can initiate in crack elements located between each pair of finite elements and can propagate in any path that the boundary and loading conditions require according to non-linear fracture mechanics criteria. Fluid channels are also defined between pairs of finite elements simulating the inter-connected flow paths through porous media. Four models of the rock mass are created in this study: (i) homogeneous-impermeable, (ii) homogeneous-permeable, (iii) heterogeneous-impermeable matrix, and (iv) heterogeneous-permeable matrix. Heterogeneous rock masses contain a discrete fracture network (natural fractures) in the rock mass structure. Hydraulic fracturing is modelled in domains of 40×40 m2 with the four different structures and mass transport capacities, and the results are compared to each other. The results highlight the significant effect of diffusive fluid flow through rock blocks, in addition to the flow through fracture network, on the global hydromechanical behaviour of the rock mass. These results help to understand the governing hydromechanical processes taking place in fractured rocks with matrix of different permeability, such as granites, shales, carbonate rocks, and sandstones and the extent of complexities required to model their behaviour to achieve reasonable accuracy.

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