Proceedings 56th US Rock Mechanics / Geomechanics Symposium最新文献_第5页

ASSESSING THE EFFECT OF IN-SITU STRESS CONDITIONS IN BACK-ANALYSIS OF ROCK MASS PARAMETERS OF TUNNELS USING MACHINE LEARNING TECHNIQUES 利用机器学习技术评估地应力条件对隧道岩体参数反分析的影响

Proceedings 56th US Rock Mechanics / Geomechanics Symposium Pub Date : 2022-06-26 DOI: 10.56952/arma-2022-0059

A. Khetwal, M. Gutierrez

{"title":"ASSESSING THE EFFECT OF IN-SITU STRESS CONDITIONS IN BACK-ANALYSIS OF ROCK MASS PARAMETERS OF TUNNELS USING MACHINE LEARNING TECHNIQUES","authors":"A. Khetwal, M. Gutierrez","doi":"10.56952/arma-2022-0059","DOIUrl":"https://doi.org/10.56952/arma-2022-0059","url":null,"abstract":"One approach to improve the reliability of predicting the response of tunnels is the \"design as you go\" method, where tunnel response is monitored during tunneling using field instrumentation. In the present study, various machine learning (ML) techniques are evaluated, and the best approach is proposed for the back-analysis of tunnel response. Incorporating in-situ stress conditions in back analysis is also essential as these are responsible for short- and long-term deformations. The study aims at predicting the cohesion and friction angle for a tunnel by setting the monitoring data and in-situ stress conditions. The ML techniques are combined with the results obtained from the commercially available finite difference code FLAC, widely used in geotechnical modeling. The ML algorithm with maximum accuracy is then used to determine the input parameters using the synthetic monitoring data. The present study evaluates a single tunnel with an overburden of 1000 m and an in-situ stress ratio ranging from 0.25 to 3 to prepare a training and validation set. The results show that with an acceptable 0.1% error, the Levenberg-Marquardt Back-Propagation Method (LMBP) of Artificial Neural Network (ANN) is found to be the most suitable ML algorithm.Keywords: Machine learning, in-situ stress ratio, back analysis, FLAC, neural network, tunnel","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121347065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Vermiculite as an Anti-Sag Additive for Water-Based Drilling Fluids 蛭石作为水基钻井液的抗凹陷添加剂

Proceedings 56th US Rock Mechanics / Geomechanics Symposium Pub Date : 2022-06-26 DOI: 10.56952/arma-2022-0167

Salem Basfar, Ashraf Ahmed, S. Elkatatny, B. Bageri

{"title":"Vermiculite as an Anti-Sag Additive for Water-Based Drilling Fluids","authors":"Salem Basfar, Ashraf Ahmed, S. Elkatatny, B. Bageri","doi":"10.56952/arma-2022-0167","DOIUrl":"https://doi.org/10.56952/arma-2022-0167","url":null,"abstract":"Barite is widely used as a weighing material since it has several advantages such as high specific gravity, readily accessible, and environmentally benign. Even though, several difficulties with barite particle settling particularly at high-pressure high-temperature drilling operations and removal efficiency necessitate further investigation. The utilization of magnesium-aluminum-iron silicate (vermiculite) with its ecofriendly effect was studied in this work as an additive for improving the drilling fluid characteristics. Variable concentration of vermiculite was added to the water-based mud (WBM) to address the static and dynamic sag tendencies at 250 and 120 °F, respectively. Furthermore, the influence of vermiculite on rheological characteristics and filtration performance was studied under HPHT circumstances. The sagging experiments showed that adding 4 lb/bbl vermiculite improved the WBM stability properties by increasing the suspension capacity of barite particles. Also, this amount of vermiculite significantly enhanced the rheological characteristics as the plastic viscosity to yield point ratio (YP/PV) was increased from 1.6 to 2.5. The HPHT filtration showed that 4 lb/bbl decreased the filter cake thickness by 37.5% and reduced the filtrated volume by 39%.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126930836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Coarse-graining methods for the modified JKR contact model on a triaxial compression test 修正JKR接触模型三轴压缩试验的粗粒化方法

Proceedings 56th US Rock Mechanics / Geomechanics Symposium Pub Date : 2022-06-26 DOI: 10.56952/arma-2022-0210

Daniyar Kazidenov, F. Khamitov, Y. Amanbek

{"title":"Coarse-graining methods for the modified JKR contact model on a triaxial compression test","authors":"Daniyar Kazidenov, F. Khamitov, Y. Amanbek","doi":"10.56952/arma-2022-0210","DOIUrl":"https://doi.org/10.56952/arma-2022-0210","url":null,"abstract":"The Discrete Element Method (DEM) modeled by coarse-graining approaches has been gaining importance in many applications including a triaxial compression test that represents the key micromechanical behaviors of deformable solids. In this work, the triaxial compression test has been investigated using a realistic particle-size distribution sample that replicates the weak cemented sandstone in Kazakhstan. The simulation was performed by the modified Johnson-Kendall-Roberts (JKR)-based DEM model with cohesive contact forces. According to the model, bonds between particles are broken at the maximum value of the normal contact force, and no new bonds are formed after the breakage. In this research, we implemented the coarse-graining methods for the modified JKR model. A scaling law was developed for each material parameter in the model such as density, surface energy density, Young's modulus, Poisson's ratio, friction and restitution coefficients . In addition, those approaches were combined with the same statistic weight (SSW) and same size parcel (SSP) scaling methods in order to scale the polydisperse particles. These combined methods are based on the conservation of mass and momentum by applying statistic weights to the particle diameters. First, the original particle simulation with the modified JKR settings was validated with the experimental data. Then, the stress-strain response and bonding behavior were compared between the original particle system and coarse-grained simulations. There is a good agreement between the results obtained from the original particle system and coarse-grained particle models. Moreover, the speedup of the coarse-grained simulations in parallel computing is achieved approximately 15 times faster than the original particle system with the same number of cores.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116806350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Simulation-Based Patterns Optimization of Enhanced Geothermal System 基于仿真的增强型地热系统模式优化

Proceedings 56th US Rock Mechanics / Geomechanics Symposium Pub Date : 2022-06-26 DOI: 10.56952/arma-2022-0785

Jerjes Porlles Hurtado, H. Jabbari

引用次数: 0

Modeling Thermomechanical Failure and Entrainment of Structural and Geological Materials into a Nuclear Fireball 模拟结构和地质材料进入核火球的热力学破坏和夹带

Proceedings 56th US Rock Mechanics / Geomechanics Symposium Pub Date : 2022-06-26 DOI: 10.56952/arma-2022-0736

Joseph Morris

引用次数: 0

Analysis of Pillar Strength and Design in a Karst-affected Underground Stone Mine 岩溶影响下地下石矿矿柱强度分析与设计

Proceedings 56th US Rock Mechanics / Geomechanics Symposium Pub Date : 2022-06-26 DOI: 10.56952/arma-2022-0486

A. Soni, J. Monsalve, N. Ripepi

{"title":"Analysis of Pillar Strength and Design in a Karst-affected Underground Stone Mine","authors":"A. Soni, J. Monsalve, N. Ripepi","doi":"10.56952/arma-2022-0486","DOIUrl":"https://doi.org/10.56952/arma-2022-0486","url":null,"abstract":"Underground stone mines are often prone to karst formations created by the gradual erosion of carbonate rocks due to groundwater flow. The prevalent fracture network in these stone deposits offers favorable conditions for acidic dissolution which leads to the formation of large karst cavities. The interaction of these cavities with the extensive presence of discontinuities is the major cause of ground control problems encountered during stone mining operations. This paper presents a case study of the effect of the karst cavity on the strength of a pillar in an underground stone mine. Numerical analyses show that presence of these voids in a pillar contributes to a considerable decrease in load-bearing capacity. Any excavation or blasting into the affected areas may pose a safety hazard to the miners. This may also disrupt production and burden the planned mine operations. The study for estimating pillar strength using numerical modeling could provide a pragmatic approach to designing future pillars affected by karsts. The shape and volume of the cavities inside the concerned pillar were approximated using ground-penetrating radar (GPR) surveys. LiDAR scans were used to map the discontinuity network around the pillars, and a Discrete Fracture Network (DFN) was created to simulate the joint network in the pillar’s rock mass. The behavior of the pillar with the increase in axial compressive stress was observed with the help of Distinct-element modeling (DEM) using 3DEC. The pillar model is simulated using Elastic and Mohr-Coulomb constitutive models. Two scenarios are presented to assess the pillar strength with and without the presence of karst. Pillar strength is compared to the estimated current stress levels to understand the potential for improvement in the pillar design. The research emphasizes the importance of pillar design while maximizing safety and production in underground stone mines with karst cavities to prevent pillar instability or local roof failures.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117020085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Westerly granite anisotropy study 西风花岗岩各向异性研究

Proceedings 56th US Rock Mechanics / Geomechanics Symposium Pub Date : 2022-06-26 DOI: 10.56952/arma-2022-0057

T. Lokajíček, M. Petružálek, T. Svitek

{"title":"Westerly granite anisotropy study","authors":"T. Lokajíček, M. Petružálek, T. Svitek","doi":"10.56952/arma-2022-0057","DOIUrl":"https://doi.org/10.56952/arma-2022-0057","url":null,"abstract":"Westerly granite (WG) is well known rock, believed to be isotropic. We studied four samples of WG heated between 100°C and 600°C, by ultrasonic sounding on spherical samples under hydrostatic pressure up to 400 MPa, neutron diffraction on identical samples and scanning electron microscopy (SEM). Thermal treatment studies are important for localities like nuclear waste storages, geothermal projects, rock and earthquake mechanics. All measurements were done at room temperature. The 3D distribution of P-wave velocities at high pressures reflects intrinsic structure and even though the anisotropy is low, the orientation of the minimum velocity corresponds to the highly preferred orientation of plagioclase (010) and biotite (001). Image analyses showed that there is also preferred orientation of microcracks regardless of their size and thermal treatment level. Neutron diffraction measurements of the samples heated to 100°C and 600°C confirm weak intrinsic elastic anisotropy, which remain unchanged due to the thermal treatment. We can assume that in Westerly granite there are two types of anisotropy: crystal preferred orientation which was formed during igneous crystallization and second one is due to the oriented microcracks which have been formed during tectonic exhumation or during sample excavation in the quarry. Both seems to be unrelated.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132299844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Permeability-Friction Relationships for Propped Fractures in Shale 页岩支撑裂缝的渗透率-摩擦力关系

Proceedings 56th US Rock Mechanics / Geomechanics Symposium Pub Date : 2022-06-26 DOI: 10.56952/arma-2022-0628

Jiayi Yu, Jiehao Wang, Yan Li, A. El-Fayoumi, Ruiting Wu, D. Liu, Peggy Rijken, A. Rathbun, D. Elsworth

{"title":"Permeability-Friction Relationships for Propped Fractures in Shale","authors":"Jiayi Yu, Jiehao Wang, Yan Li, A. El-Fayoumi, Ruiting Wu, D. Liu, Peggy Rijken, A. Rathbun, D. Elsworth","doi":"10.56952/arma-2022-0628","DOIUrl":"https://doi.org/10.56952/arma-2022-0628","url":null,"abstract":"We investigate controls on fluid transfer into massive hydraulic fractures due to reactivation of, and proppant penetration into, oblique fractures transecting the main fracture face during long-term reservoir depletion through tightly constrained laboratory experiments. Permeability evolution of fracture-contained proppant permeability/conductivity is highly sensitive to both normal stress and proppant loading concentration and less sensitive to shear displacement rate. By experimentally examining the shale and steel fractures – as an analog to end-member manifestations of soft/weak and hard/strong fracture surfaces – and calibrating using granular mechanics models (DEM), we conclude that the evolution of friction-permeability relationship of a propped shale fracture is largely controlled by the rock friction/rigidity. To be specific, propped hard/strong fractures show a continuous permeability decay at near-constant rate throughout a shear deformation. Conversely, permeability of soft/weak fractures declines rapidly during pre-steady-state-friction then declines more slowly after transitioning to steady-state-friction. We posit that weak fracture walls accommodate shear deformation via the combined effects of distributed deformation across the interior of the proppant pack and from sliding at the fracture-proppant interface. However, strong rocks accommodate shear deformation primarily through distributed deformation within the proppant pack.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124568759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Improved Upscaling Methods for Carbonate Rock Image Data 碳酸盐岩图像数据的改进升级方法

Proceedings 56th US Rock Mechanics / Geomechanics Symposium Pub Date : 2022-06-26 DOI: 10.56952/arma-2022-0688

A. K. Shahi, Anil Kumar, K. H. Singh, R. Gamage

{"title":"Improved Upscaling Methods for Carbonate Rock Image Data","authors":"A. K. Shahi, Anil Kumar, K. H. Singh, R. Gamage","doi":"10.56952/arma-2022-0688","DOIUrl":"https://doi.org/10.56952/arma-2022-0688","url":null,"abstract":"Volumetric image data of rocks often need sophisticated image processing steps in any rock physics and petrophysics workflow. While the segmentation is highly dependent on the quality of data, a trade-off between resolution and field of view is inevitable. This work attempts to resolve this using multiple-point statistics that have long been used for generating synthetic images, though mostly applied to sandstone rocks where the heterogeneity is significantly less than that of carbonates. These algorithms work by sequentially populating a grid to emulate the observed image. However, finding the optimum kernel parameters is crucial to capturing the spatial characteristics of the data. Also, when dealing with multiple images, finding a single set of kernel parameters might not be a trivial task. Further, these methods work by computing a covariance kernel that scales as the third power with the number of training examples, thus not scaling well with more data. Therefore, we seek to design a single image-based upscaling method that would help alleviate these difficulties. We test the proposed methodology on carbonate rock sample data which are known for their complexities at various scales. In this study images of 4 samples are considered. An upsample-deblur is developed that consistently works better than the conventional bicubic interpolation-based upsampling technique. For this, a low-resolution 2D image sample is extracted from an X-ray microtomography dataset which was then subjected to a Random Forest-based upsampling algorithm. It is found that the data from low scale could be improved to form a single super-resolution image. The algorithm produces an image that is always better than the bicubic algorithm. We anticipate this strategy would help design advanced algorithms where the amount of training examples is less.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125323801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Review of Tensile Strength Measurement in Rock with Laminations/Bedding and its Implication on Rock Mechanical Properties and Fracture Pressure Gradient Estimation 层状/层理岩石抗拉强度测量及其对岩石力学特性和破裂压力梯度估算的意义

Proceedings 56th US Rock Mechanics / Geomechanics Symposium Pub Date : 2022-06-26 DOI: 10.56952/arma-2022-2374

D. Moronkeji, Christopher Wolfe

{"title":"A Review of Tensile Strength Measurement in Rock with Laminations/Bedding and its Implication on Rock Mechanical Properties and Fracture Pressure Gradient Estimation","authors":"D. Moronkeji, Christopher Wolfe","doi":"10.56952/arma-2022-2374","DOIUrl":"https://doi.org/10.56952/arma-2022-2374","url":null,"abstract":"The tensile strength (TS) has been used extensively in estimating the unconfined compressive strength of a rock formation when the number of UCS measurements are limited. A well-known method of determining the TS of a rock sample is the Brazilian tensile strength (BTS) test. In horizontal rock samples with bedding planes (BP), lower horizontal tension at failure typically occurs in a BTS test when loading the sample parallel to bedding (PLTB) versus perpendicular to bedding (PDTB). This is because bedding activation failure mode dominates in PLTB versus typical central fracture failure mode in PDTB. Numerous studies have been done on BTS; however, this study is a review of the implication of the differences in BTS obtained between PLTB and PDTB loading to observe the effect of BP. In this review, we measured BTS tests and observed variation between PLTB and PDTB measurements. These differences have implications on the prediction of rock mechanical properties and fracture pressure gradient estimation. This study shows an overall good fit to a relationship existing to derive a useful correlation between PLTB and PDTB tensile strength measurements that can be used in unconventional shale resources when the amount of core samples is limited or restricted to horizontal rotary sidewall cores.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121696413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0