Heinz Konietzky

TU Bergakademie Freiberg

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

Thomas Frühwirt

Graz University of Technology

Zhengyang Song

University of Science and Technology Beijing

Martin Herbst

TU Bergakademie Freiberg

Fei Wang

Northeastern University

Wengang Dang

Sun Yat-sen University

L. te Kamp

Itasca Consultants (Germany)

Xin Tan

Hunan University

Qingsheng Bai

TU Bergakademie Freiberg

P.L.P. Wasantha

Victoria University

Xibing Li

Central South University

Cooperative Institutions

TU Bergakademie Freiberg

China University of Mining and Technology

Central South University

Northeastern University

Chinese Academy of Sciences

Shandong University of Science and Technology

Helmholtz Centre for Environmental Research

Chongqing University

Ministry of Education of the People's Republic of China

Sichuan University

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

A new continuum-based constitutive model for the simulation of the inherent anisotropy of Opalinus clay

Tunnelling and Underground Space Technology (2019)

Mohamed Ismael Heinz Konietzky Martin Herbst

Mohr–Coulomb theory

Brittleness

Bedding

Stress path

Hardening (computing)

Viscoplasticity

10.1016/j.tust.2019.103106

Cite

Citations (18)

Numerical analysis of soil pipe effects on hillslope water dynamics

Acta Geotechnica (2009)

Raj Sharma Heinz Konietzky Ken’ichirou Kosugi

10.1007/s11440-009-0104-5

Cite

Citations (17)

Simulating the Single- and Multi-Stage Hydraulic Fracturing: Some Insights Gleaned from Discontinuum and Continuum Modelling

Procedia Engineering (2017)

Heinz Konietzky P.L.P. Wasantha Fabian Weber

Discontinuum and continuum modelling approaches were used to simulate the single- and multi-stage hydraulic fracturing. Two-dimensional discontinuum modelling of single-stage fracturing revealed a marked modification of the stress field in the vicinity of the fracture (stress shadow effect) during fracture propagation which was identified as the reason for the significant asymmetry of fracture propagation about the wellbore observed for multi-stage fracturing. Allowing the fracturing fluid to flow back after each fracturing stage appeared to minimize this stress shadow effect on fracture propagation geometry. Three-dimensional discontinuum modelling results showed similar behaviors as two-dimensional modelling. Inclined orientation of wellbores with respect to principal stresses and enabling fluid backflow after each fracturing stage were found to be effective to minimize the stress shadow effect on fracture propagation geometry after three-dimensional discontinuum modelling. Our three-dimensional continuum modelling of hydraulic fracture propagation so far revealed some promising results demonstrating its capability to simulate hydraulic fracturing applications. Finally, the specific and contrasting features of both approaches are discussed here giving some useful insights into both approaches to assist users with choosing the appropriate method for a particular simulation project.

Fracturing fluid

Backflow

Multi stage

Stress field

10.1016/j.proeng.2017.05.283

Cite

Citations (9)

A Novel Method for Rock Permeability Determination Based on the Pressure Pulse Decay Method and Inverse Numerical Simulations

Rock Mechanics and Rock Engineering (2024)

Qingquan Liu Biao Lv Heinz Konietzky Giovanni S. Alberti Kun Sang Lee

Inverse method

10.1007/s00603-024-04095-y

Cite

Citations (0)

Cerchar Abrasion Ratio (CAR) as a New Indicator for Assessing Rock Abrasivity, Rock–Stylus Interaction and Cutting Efficiency

Rock Mechanics and Rock Engineering (2020)

Guangzhe Zhang Heinz Konietzky

Stylus

Abrasion (mechanical)

10.1007/s00603-020-02112-4

Cite

Citations (11)

Strain Energy Dependent Numerical Simulation of Rock Fracture Initiation and Propagation Using Soundless Cracking Demolition Agents (Scda): Effects of Scda-Filled Rock Joints

V.R.S. De Silva Heinz Konietzky P.G. Ranjith U. I. Manatunga

Soundless Cracking Demolition Agents (SCDA) are gaining traction as an innovative technique for controlled rock fracturing in applications such as underground energy, mineral extraction, and excavation. This paper presents a novel numerical approach to simulate SCDA-charged rock fracture initiation using the strain energy density of SCDA. This approach eliminates the need for prior knowledge of the peak expansive pressure developed in a rock, a common requirement in conventional SCDA modelling. An empirically derived model is presented which captures the rate of energy release in SCDA as a function of applied strain to the surrounding material. The model was implemented in the 3-dimensional Distinct Element Code by applying an exponential strain-rate decay function. The proposed fracture stimulation method accurately mimics the expansion behaviour and finite strain energy release from SCDA expansion. The method was extended to simulate SCDA expansion in rock joints. The SCDA expansion method was assessed by creating a numerical model in which a central injection well was intersected by a horizontal joint and SCDA expansion was simulated in the injection well and the joint. The simulations were verified against laboratory fracture experiments. The model was extended to evaluate the fracturing performance of SCDA under varying joint roughness and confining pressures. SCDA expansion in rock joints introduces an additional compressive stress field that inhibits fracture initiation and propagation near the joint. Increasing fracture roughness suppressed fracture growth, but led to more fracture nucleation points around the injection well and shear damage at the joint interface. The simulation method employed shows sensitivity to confining pressures and simulates the fracturing potential of SCDA in different rocks subjected to confining pressures without requiring further calibration of the SCDA expansion parameters. The proposed numerical simulation method improves the accuracy in investigating the fracturing potential of expansive agents over existing simulation methods for SCDA.

Strain (injury)

Strain energy

10.2139/ssrn.4679631

Cite

Citations (0)

Dynamic compressive strength and failure mechanisms of microwave damaged sandstone subjected to intermediate loading rate

Transactions of Nonferrous Metals Society of China (2022)

Pin WANG Tubing Yin Xibing Li Heinz Konietzky

To investigate the influence of microwave heating on the dynamic behavior and failure mechanisms of rock, dynamic compression tests were conducted on microwave-irradiated sandstone specimens using a modified split Hopkinson pressure bar (SHPB) system. Experimental results show that microwave radiation can effectively weaken the compressive strength of sandstone. Rock specimens show three different failure modes under impact load: tensile failure, tensile—shear composite failure and compressive—shear failure. The dynamic Poisson's ratio, calculated using the measured P- and S-wave velocities, is introduced to describe the deformation characteristics of sandstone. With the increase in microwave power and heating time, the Poisson's ratio declines first and then increases slightly, and the turning point occurs at 244.6 °C. Moreover, the microstructural characteristics reveal that microwave radiation produces dehydration, pore expansion, and cracking of the rock. The damage mechanisms caused by microwave radiation are discussed based on thermal stress and steam pressure inside the rock, which provides a reasonable explanation for the experimental results.

Split Hopkinson Pressure Bar

Dynamic range compression

10.1016/s1003-6326(22)66052-7

Cite

Citations (3)

Numerical Simulation of Turbulent Fluid Flow in Rough Rock Fracture: 2D Case

Rock Mechanics and Rock Engineering (2023)

M. Finenko Heinz Konietzky

Abstract We investigate both laminar and turbulent flow regimes in a rough-walled rock fracture via numerical CFD simulations. While previous studies were limited to either fully viscous Darcy or inertial Forchheimer laminar flow regimes, we chose to cover the widest possible Reynolds number range of 0.1– $$10^6$$ 10 6 . We introduce CFD simulation of a turbulent flow for rough-walled fractures, implementing RANS approach to turbulence modeling. We focus on 2D fracture geometries and implement changes in both shear displacement and wall roughness, systematically examining their effect on fracture permeability and friction factor in a manner similar to the fundamental studies of the flow in rough-walled pipes. For a curvilinear fracture, laminar flow becomes non-stationary between $$Re \, {\sim } \, 10^2$$ R e ∼ 10 2 – $$10^3$$ 10 3 , earlier for larger shear displacement and wall roughness. Laminar–turbulent transition starting at $$Re_{\textrm{cr}} \, {\sim } \, 2300$$ R e cr ∼ 2300 may lead to a sharp drop in permeability depending on the fracture geometry; this gap vanishes for larger shear displacement and wall roughness. Depending on the fracture geometry, bottlenecks closing with shear become a major negative factor for the overall permeability.

10.1007/s00603-023-03551-5

Cite

Citations (2)

Prediction of Brickwork Failure Using Discrete-Element Method

Journal of Materials in Civil Engineering (2018)

Wei Chen Heinz Konietzky Chao Liu Helin Fu Jiabing Zhang

In this study, a discrete element approach is used to simulate brickwork. Bricks are represented by blocks with Mohr-Coulomb plasticity and strain softening. The mortar consists of elastic Voronoi blocks connected by elastoplastic contacts. First, the parameters for brick and mortar are calibrated through a series of bending and compression tests conducted on brick and mortar samples, respectively. Then, shear tests on triplets are performed and Brazilian tests on disc samples are investigated by the numerical approach. Compared with results from other researchers, the numerical model can not only reproduce accurate strength values of the samples but is also able to display the damage development and fracture patterns of the brick as well as mortar.

Brickwork

Brick

Cuboid

10.1061/(asce)mt.1943-5533.0002431

Cite

Citations (9)

Numerical modelling of natural rock formations to estimate stability using the example of a sandstone massif in Saxony / Numerische Modellierung natürlicher Felskomplexe zur Abschätzung der Standsicherheit am Beispiel des Wehltumkomplexes in der Sächsischen Schweiz

Geomechanics and Tunnelling (2012)

Martin Herbst Heinz Konietzky

Abstract Statements about stability, weathering behaviour and possible rockfalls affecting a real rock massif were made possible by creating a 3D surface/volume model, using as example the “Großer Wehturm” rock massif, using the high‐resolution laser scanning process together with rock mechanical 3D model calculations. The emphasis of this paper is the mathematical modelling, particularly the generation of the 3D model from the surface point cloud and the simulation possibilities. The numerical calculations are based on the Discrete Element Method, considering the rock matrix and joint or bedding interfaces. The 3D modelling delivers, in addition to answers to questions about the extent and degree of deformations and movement mechanisms, knowledge relevant to the transfer of the procedure to other locations. Aussagen zu Standsicherheit, Verwitterungsverhalten und möglichen Felsstürzen an konkreten Felsmassiven wurden mittels der Erstellung und Auswertung eines 3D‐Oberflächen‐/Volumenmodells am Beispiel des Felsmassivs “Großer Wehturm” unter Nutzung des hochauflösenden Laserscansverfahrens mit kombinierter felsmechanischer 3D‐Modellberechnungen durchgeführt. Der Schwerpunkt dieser Veröffentlichung liegt auf der Numerik, insbesondere der 3D‐Modellgenerierung aus der Oberflächenpunktwolke und den Simulationsmöglichkeiten. Die numerischen Berechnungen basieren auf der dreidimensionalen Diskreten Elemente Methode unter Berücksichtigung der Gesteinsmatrix und Kluft‐ bzw. Schichtgrenzen. Die 3D‐Modellierung liefert neben Antworten auf Fragen zu Umfang und Ausmaß von Deformationen und Bewegungsmechanismen auch Erfahrungen bzgl. der Übertragung auf andere Standorte.

Massif

10.1002/geot.201200026

Cite

Citations (1)