Joint Sets Research Articles

An index based on fracture length and aperture to predict groundwater inflow rates in tunnels excavated in fractured-rock

The surface area of the fractures at the wall of a tunnel is used to develop a representative index, as inflow index, for the prediction and the classification of the inflow rate to a tunnel that is excavated in a fractured rock mass. For this purpose, an analytical model has been developed for the calculation of the inflow index based on geometrical characteristics of the discontinuities and of the tunnel. The result of the analytical model is validated by numerical simulations using 3DEC version 7.0 software. Furthermore, the simulation results demonstrate the capacity of the inflow index to predict the inflow rate to the tunnel. At a constant value of the water head, the inflow rate to the tunnel increases with increasing value of the inflow index. In addition, the inflow rate could be classified to various levels, based on the values of inflow index. The study has identified that the hydraulic aperture, joint spacing, tunnel radius and the angle between tunnel and normal to joint sets have the most important impacts on the inflow index and among them, the effect of hydraulic aperture is the most important one.

Estimation of non-stationary return levels of extreme temperature by CMIP6 models

Abstract This study aims to investigate the effects of climate change on return level of extreme maximum temperature (EMT) events in Iran. To this end, the CRU gridded dataset was used to collect EMT for the 1901–2014 period and future data were projected from four available CMIP6 models, where the BCC-CSM2-MR performed best under the latest Shared Socioeconomic Pathways-Representative concentration pathways (SSPs-RCPs) emission scenarios for the 2015–2100 period. The non-stationary state of the distribution was considered under three models GEV0 (location and scale parameters are constant), GEV1 (nonstationary of location), and GEV2 (nonstationary of scale) based on the evaluation criteria . The findings indicate that, when using a non-stationary approach and considering the SSP5-8.5 scenario for a 2-year return period, the return level of extreme temperature increased by up to +4°C compared with the stationary approach, while considering a non-stationary approach without climate change, the increase in the return level of extreme temperature was much smaller(up to +0.7°C). MCMC and DE-MC showed no significant differences and demonstrated that all stations are non-stationary in terms of the location parameter (GEV1).

Shear performance of elliptical head one-sided bolt double-lapped joint with plug-in gasket

One-sided bolts are commonly used for bolted connections between closed section members to address the issue of insufficient space for nut installation. Among them, the elliptical head one-sided bolt uses the difference in length between its long and short axes. This allows the bolt head to be inserted into the elliptical bolt hole and subsequently rotated by 90 degrees, effectively achieving anchoring. But the use of elliptical bolt holes may cause some problems, such as bolt slippage and stress concentration around the bolt holes. In this paper, building upon the elliptical head one-sided bolt concept, a novel structure for one-sided bolted connection is proposed, incorporating a plug-in gasket to improve the mechanical properties of the elliptical one-sided bolted joints. Six sets of steel plate double-lapped joints, connected by elliptical head one-sided bolts and plug-in gaskets, were designed for shear resistance tests. A finite element model was designed using ABAQUS, based on the test specimen parameters. By comparing the simulation results with the experimental findings, the reinforcing effect of the gasket on joint stress was analyzed and validated. The results show that the plug-in gasket effectively resolves the excessive slippage issues and enhances the initial stiffness of the joint. Moreover, when pressure is applied to the bolt hole, the plug-in gasket reduces the stress concentration caused by the extrusion between the bolt hole and the bolt shank, thus preventing local premature failure of the bolt hole.

Effect of anti-inflammatory treatments on patient outcomes and concentrations of inflammatory modulators in the post-surgical and post-traumatic tibiofemoral joint setting: a narrative review.

There are several anti-inflammatory therapeutic options that can be used in the context of post-surgical and post-traumatic knee settings. Each of these options carries with it certain benefits, as well as potential issues depending on the duration and administration of each therapy. An understanding of how these anti-inflammatory drugs modulate various biomarkers of inflammation is also necessary in understanding how they can affect patient and objective outcomes following acute knee injury or surgery. This review covers the many traditional therapeutic options that have been used in treating knee injuries, as well as some natural therapeutics that have shown anti-inflammatory properties. A current review of the literature was conducted and synthesized into this narrative review. Many traditional anti-inflammatory therapeutics have been shown to be beneficial in both post-traumatic and post-surgical tibiofemoral joint settings at reducing inflammation and improving patient outcomes. However, many of these treatments have risks associated with them, which becomes problematic with prolonged, repeated administration. Natural anti-inflammatory compounds may also have some benefit as adjunctive treatment options in these settings. There are multiple different therapeutic options that can be used in acute knee settings, but the specific mechanism of injury or surgical context should be weighed when determining the best clinical approach.

Structural Analysis for Slope Stability Assessment of Selected Sites at ShurShirin Valley, Zurbatiyah Region, Eastern Iraq

Shurshirin Valley and surrounding areas are the most wonderful places as tourist areas in the east of Iraq. Many rock slopes appear as dangerous geological locations along this valley. One of the most effective geological structures on the rock slope stability is the orientation of the joints concerning the attitude of the bedding plane and the slope (inclination angle and direction), thus a geometrical analysis for joints has been performed for rock slopes along Shurshirin Valley to assess their instability; Five stations have been studied for both Tertiary rocks and Alluvial fan sediments which exist in three stations only. The main failure types in the study area are rock fall in all stations, toppling in two stations, and (potentially wedge sliding )in one station along the intersection line of the joint sets concerning the lateral slope of station No.2. While the suggested ways to improve the slope stability and protection versus rock failures are re-slope, trimming, ditches, and wire mesh.

Stiffness and damping characteristics of jointed rocks under cyclic triaxial loading subjected to prolonged cyclic loading

A modelled rock joint set featuring a rough joint surface inclined at 60° was fabricated, and cyclic triaxial and conventional monotonic triaxial experiment series were carried out at various confining stresses. Cyclic deviatoric loading was applied up to 500,000 cycles at 8 Hz frequency to evaluate the impact of prolonged repeated loading on the stiffness and damping properties of rock joints and their variation with irreversible axial strain. The analysis of the experimental data revealed that, under the tested conditions, the accumulation of irreversible axial strain exhibited a progressive rise as the repeated loading advanced, particularly in the early stage of deformation. Furthermore, the resilient moduli demonstrated a downward trend in relation to cumulative irreversible axial strain, while the damping ratio showed a rapid decrease initially and then increased slowly with cumulative irreversible axial strain. Moreover, with the rise in confining stress, the accumulated irreversible axial strain reduced while resilient moduli and Young’s moduli increased, and the damping ratio decreased. Through nonlinear regression analysis, empirical relationships for the resilient moduli variation with the irreversible axial strain and variation of critical dynamic irreversible axial strain with cyclic stress ratio were developed.

Evaluating the Accuracy of Bonded Block Models for Prediction of Rockmass Analog Mechanical Behavior.

Large-scale rock formations, referred to as "rockmasses", consist of intact rock separated by pre-existing discontinuities (i.e., joints). The mechanical behavior of rockmasses is difficult to directly test in the laboratory due to the required specimen scale. Instead, Synthetic Rockmass Modeling (SRM) is often used to simulate field-scale rockmass behavior. SRM requires a calibrated discrete element model (DEM) of intact rock combined with a Discrete Fracture Network (DFN). While the SRM concept has been informally determined to provide reasonable results based on practitioner experience, detailed and peer-reviewed validation is lacking. The goal of this study was to evaluate the predictive capabilities of the SRM method. Previously available data on intact and rockmass analog laboratory specimens of Blanco Mera granite containing DFNs with two joint sets were used as a basis for the SRM created in this study. Specifically, the intact DEM was a Bonded Block Model (BBM), generated to match the grain structure and composition of Blanco Mera granite and the model's input parameters were calibrated so that the behavior of the BBM matched that of the intact laboratory specimens. The predictive capabilities of the model were evaluated by recreating the DFN from the jointed laboratory specimens within the intact BBM and comparing the behavior of the jointed models back to the jointed laboratory specimens, which has not been previously studied in the literature. The BBM was found capable of approximately predicting the behavior of rockmass analog specimens containing a pre-existing DFN without further calibration, which shows potential for the use of SRM in both industry and academia. Specifically, the BBM predicted the strength, dilatancy, and microfracturing behavior of the jointed laboratory specimens.

Stress–Structural Failure of a 610 m Crushing Station Left-Side Tunnel Section in Jinchuan II Mine: A Numerical Simulation Study

To address the stress–structural failure phenomenon that can be induced by the excavation of a left-side tunnel section of a 610 m crushing station, an unmanned aerial vehicle was used in this study to collect the geological conditions and rock mass information of the working face, and important geometric information such as the attitude and spacing of rock mass were extracted. Based on the identified attitude and spacing information, a three-dimensional rock mass structure and numerical simulation model of the 610 m crushing station left-side tunnel section were constructed using discrete element numerical simulation software (3DEC) (version 5.0). The results show that the surrounding rock instability of the left-side tunnel section of the 610 m crushing station is controlled by both the stress field in the contact zone between reddish-brown granite stratum and the gray-black-gray gneiss stratum. The cause of stress–structural failure is that the joint sets (JSet #2 and JSet #3) are most likely to form unfavorable blocks with the excavation surface due to unloading triggered by the excavation. Therefore, stress–structural failure disasters in jointed strata sections are one of the key issues for surrounding rock stability during crushing station excavation. It is suggested to adopt ‘optimized excavation parameters + combined support forms’ to systematically control stress–structural failure after unloading due to the excavation from three levels: surface, shallow, and deep. The stress–structural failure mechanism of deep rock mass is generally applicable to a large extent, so the results of this research have reference value for engineering projects facing similar problems around the world.

Behavior of a Rock Mass in Uplift Field Tests of Rock Anchors

AbstractRock anchors are high-capacity reinforcement measures used to stabilize large-scale infrastructures. According to the literature, they can fail in one of the four ways: (1) steel tensile failure; (2) tendon–grout interface failure; (3) grout–rock interface failure; and (4) rock mass uplift failure. Rock mass uplift field tests were performed in a limestone quarry to test this fourth failure mode. The tests were designed to induce rock mass failure around rock anchors. The ground surface heaved asymmetrically around the anchors and the pre-existing joints in the rock mass tended to open first. The seismic activity in the rock mass was greatest close to the anchor, decreasing with distance. The failure crater in the rock followed the joint sets in the rock mass, and the shape was partly controlled by the pre-existing joints. The apex angle of the failures was measured to be between 125 and 140$$^{\circ }$$ ∘ . The horizontal stress in the rock mass increased when the anchor was pulled, indicating load arching around the anchor. The observed failure was a combination of rock mass uplift and grout–rock bond failure. The measured anchor capacity was much higher than the estimated rock mass capacity using the recommended design methods of the Norwegian Public Roads Administration.

Analysis of aperture values of stratabound fractures in bedded rock: Use of the maximum likelihood method in studying a truncated data set

In this study, a truncated data set of aperture values of stratabound joints in carbonate rocks, already studied in a previous work and in which sampling of smallest fractures was problematic, has been reanalysed through regression analysis by means of Maximum Likelihood Estimation (MLE). This analysis criterion has been tested through Monte Carlo simulations, which demonstrated that MLE is able to correct the measurement bias due to truncation. The statistics corroborate as the median joint aperture value is mainly controlled by mechanical bed thickness, according to a linear regression law with non-zero intercept. The achieved results are of interest (i) from the viewpoint of statistical methodology as well as (ii) for the purpose of characterizing stratabound joint sets. With reference to point (i), the proposed method is significantly more reliable than the Least Squares Method (LSM). Therefore, it may be routinely employed in fracture analysis and potentially adapted also for other cases in which there is an analogue bias at lower limits of the sampling range. Regarding point (ii), these results provide a step ahead in characterizing and modeling of stratabound joint networks based on bed thickness data, which is relevant to identify pathways and storage systems in oil reservoir study, in hydrogeology and in all environmental problems involving ground fluids.

Joint Studies In The Western Part Of Ikom-Mamfe Basin, Lower Benue Trough, Nigeria

The Ikom-Mamfe basin, also called the Mamfe embayment, is a bifurcation of the Benue trough in southeastern Nigeria and southwestern Cameroun. The basin is about 130km long, 60km wide basin and is filled with about 4km thick sedimentary rocks. Deformational events led to gentle folding of rocks in the basin and emplacement of magmatic rocks. Systematic and detailed field studies were carried out in eight (8) locations within the study area, in which the orientations of 1437 joints and 102 veins were acquired. Two sets of orthogonal joints observed in the study exhibited symmetry with respect to the directions of the fold axes and were dominated by high-angle dips averaging about 80o. This implies a syntectonic origin of these structures also during their propagation, the maximum principal stress directions (σ1) were orientated in two different directions NW- SE and NNE-SSW for DI and D2 respectively. The relative strength of deformation during DI was greater than D2 and it was also unfolded that the ‘ac’ extension joints trending NW- SE and NNE-SSW hosted relatively thicker veins in both DI and D2. These joints served as better conduits for mineralizing fluids and also most suitable directions for future prospecting.

A Low-Cost and Fast Operational Procedure to Identify Potential Slope Instabilities in Cultural Heritage Sites

Italy is famous for its one-of-a-kind landscapes and the many cultural heritage sites characterizing the story of its regions. In central Italy, during the medieval age, some of them were built on the top of high and steep cliffs, often on the top of ancient ruins, to protect urban agglomerations, goods and people. The geographical locations of these centers allowed them to maintain their original conformation over time, but, at the same time, exposed them to a high risk of landslides. In this context, this research aimed to present an integrated and low-cost approach to study the potential landslide phenomena affecting two medieval towns. Field surveys and mapping were carried out through the use of innovative digital mapping tools to create a digital database directly on the field. Data gathered during field surveys were integrated with GIS analyses for an improved interpretation of the geological and geomorphological features. Due to the inaccessibility of the cliffs surrounding the two villages, a more detailed analysis of these areas was performed through the use of unmanned aerial vehicle-based photogrammetry, while advanced differential synthetic aperture radar interferometry (A-DInSAR) interpretation was undertaken to verify the stability of the buildings in proximity to the cliffs and other potential active failures. The results of the study highlighted the similar geometry and structural settings of the two areas. Kinematically, the intersection of three main joint sets tends to detach blocks (sometimes in high volumes) from the cliffs. The A-DInSAR analysis demonstrated the presence of a landslide failure along the northwest side of the Monte San Martino town. The buildings in proximity to the cliffs did not show evidence of movements. More generally, this research gives insights into the pro and cons of different survey and analysis approaches and into the benefits of their procedural integration in space and in time. Overall, the procedure developed here may be applied in similar contexts in order to understand the structural features driving slopes’ instabilities and create digital databases of geological/monitoring data.

Spatial Response Discrimination May Elicit a Simon Effect on a Non-Complementary Task.

When paired participants are each assigned a complementary half of the Simon task, a joint Simon effect (JSE) has been observed. Co-representation, a cognitive representation of not only one's own task but also that of the co-actor, has been one of several proposed mechanisms in the JSE. Using the response-discrimination hypothesis as a framework, we tested whether it was sufficient to highlight alternative task keys in a two-person setting in which a non-complementary task was completed to elicit a Simon effect (SE). In our design, the participant's role was to perform the Go/No-Go Simon task and the co-actor's role was to initiate each trial for the participant. In one two-person setting participant group (SK group), the same task key was assigned to both the participant and the co-actor; another group (OK) was assigned spatially opposite task keys. In a third group (joint setting, TS group), the standard joint Simon task was also completed to verify that a JSE could be replicated. We hypothesized that an SE would be elicited in the OK group, since opposite task keys would uniquely promote spatial coding. We found a weak but marginally significant SE in the OK group but not in the SK group. These results suggest that, on a non-complementary task, response discrimination may contribute to the emergence of a SE in a two-person setting, while it does not have the same impact as a complementary task completed in a joint setting (TS group) that may afford more robust response representations that reveal the enhanced so-called JSE.

Online pattern recognition of lower limb movements based on sEMG signals and its application in real-time rehabilitation training

AbstractAn online pattern recognition method of lower limb movements is proposed based on the personalized surface electromyography (sEMG) signals, and the corresponding experimental researches are performed in the rehabilitation training. Further, a wireless wearable acquisition instrument is used. Based on this instrument, a host computer for the personal online recognition and real-time control of rehabilitation training is developed. Three time-domain features and two features in the nonlinear dynamics are selected as the joint set of the characteristic values for the sEMG signals. Then a particle swarm optimization (PSO) algorithm is used to optimize the feature channels, and a k-nearest neighbor (KNN) algorithm and the extreme learning machine (ELM) algorithm are combined to classify and recognize individual sample data. Based on the multi-pose lower limb rehabilitation robot, the real-time motion recognition and the corresponding rehabilitation training are carried out by using the online personalized classifier. The experimental results of eight subjects indicate that it takes only 6 min to build an online personalized classifier for the four types of the lower limb movements. The recognition between switches of different rehabilitation training movements is timely and accurate, with an average recognition accuracy of more than 95%. These results demonstrate that this system has a strong practicability.

Rock mass joint set identification at Draa Sfar mine in Morocco through stereographic projection and K-means clustering

Rock mass joint set identification at Draa Sfar mine in Morocco through stereographic projection and K-means clustering

A Numerical Method for Evaluating the Collapse of High-Steep Scarp Slopes Based on the Bonded Block Model–Discrete Fracture Network Model

Geotechnical engineering works in deep-incised valleys or open-pit mining areas often encounter high-steep scarp slopes with a slope angle greater than 75°. This type of slope directly threatens the safety of construction personnel, so assessing their stability is essential to ensure construction safety. The natural geometry of high-steep scarp slopes possesses complexity in terms of geometric morphology, structural features of rock mass, and occurrence mechanisms of collapse. There is little research and less emphasis on the evaluation of the collapse risk of high-steep scarp slopes. In particular, the fracture of intact rock or rock bridges is generally ignored in the analysis of collapse processes. A bonded block model (BBM)–discrete fracture network (DFN) coupling characterization model for the high-steep scarp slope is proposed based on a high-steep scarp slope containing dominant joint sets on the left bank of the dam site of the Huangzangsi Water Conservancy Project (Qinghai Province, China). By using the model, the complex geometric forms of the surface of the high-steep scarp slope are quantified, and the fracture process of falling rock masses as well as the controlling effect of dominant joints on the collapse of the scarp slope are revealed. A strength reduction method based on the BBM–DFN model is constructed, and the safety factor of the collapse-prone scarp slope is evaluated. The research results show that (1) the BBM–DFN model can be used to describe the local collapse process; (2) the occurrence of dominant joints plays an important part in controlling the collapse process; (3) there are differences in the safety factor of the scarp slope with different coupling methods; the collapse and failure modes also differ. For safety considerations, the safety factor of the scarp slope on the left bank of the dam site area is determined to be 1.85. The research findings can be used to guide the safety assessment of high-steep scarp slopes and the formulation of both collapse risk prevention and control measures to ensure construction safety in high-steep scarp slope areas.

Extrapolation Paleostress Orientations Deduced from Joints Analyses at Spi Rais and West Part of Chai Gara Anticlines, Duhok Area, Kurdistan Region, Iraq

Spi Rais anticline (East part of major Bekhair anticline) and western part of Chia Gara anticline were chosen to study joint paths. They are located within the highly folded zone of the western zagros fold and thrust belt, Iraqi segment. These anticlines arranged in an en-echelon pattern and they expose rocks range in age from Late Cretaceous to Late Miocene. The Late Cretaceous (Campanian – Maastrichtian) succession represented by Bekhme and Shiranish Formations. The lithologies of these rocks are competent and consist of limestone, dolomitic limestone and marly limestone whichare favorable to joint development. Different types of joints were developed in such rocks due to stresses resulted from collision between Arabian and Eurasian (Turkish and Iranian) plates. The joint sets and systems are the most abundant fractures in the rocks of the study area. The chronological relationships of the joints refer that the area had witnessed multiple tectonic pulses in the form of compressional and extensional stresses. The stereonet and the Win – Tensor programs were used to plot the attitudes of joints and deduce their paleostresss orientations. Furthermore, the orientations of deduced paleostresses were plotted onto geological map of investigated area and simulated as paleo trajectories as well. The deduced paleostress direction responsible for folding in traverse 1 was (356° - 195°), in traverse 2 (330° - 168°) and in traverse 3 (353°- 163°).

Five Inhibitory Receptors Display Distinct Vesicular Distributions in Murine T Cells.

T cells can express multiple inhibitory receptors. Upon induction of T cell exhaustion in response to a persistent antigen, prominently in the anti-tumor immune response, many are expressed simultaneously. Key inhibitory receptors are CTLA-4, PD-1, LAG3, TIM3, and TIGIT, as investigated here. These receptors are important as central therapeutic targets in cancer immunotherapy. Inhibitory receptors are not constitutively expressed on the cell surface, but substantial fractions reside in intracellular vesicular structures. It remains unresolved to which extent the subcellular localization of different inhibitory receptors is distinct. Using quantitative imaging of subcellular distributions and plasma membrane insertion as complemented by proximity proteomics and biochemical analysis of the association of the inhibitory receptors with trafficking adaptors, the subcellular distributions of the five inhibitory receptors were discrete. The distribution of CTLA-4 was most distinct, with preferential association with lysosomal-derived vesicles and the sorting nexin 1/2/5/6 transport machinery. With a lack of evidence for the existence of specific vesicle subtypes to explain divergent inhibitory receptor distributions, we suggest that such distributions are driven by divergent trafficking through an overlapping joint set of vesicular structures. This extensive characterization of the subcellular localization of five inhibitory receptors in relation to each other lays the foundation for the molecular investigation of their trafficking and its therapeutic exploitation.

A webcam-based machine learning approach for three-dimensional range of motion evaluation.

Joint range of motion (ROM) is an important quantitative measure for physical therapy. Commonly relying on a goniometer, accurate and reliable ROM measurement requires extensive training and practice. This, in turn, imposes a significant barrier for those who have limited in-person access to healthcare. The current study presents and evaluates an alternative machine learning-based ROM evaluation method that could be remotely accessed via a webcam. To evaluate its reliability, the ROM measurements for a diverse set of joints (neck, spine, and upper and lower extremities) derived using this method were compared to those obtained from a marker-based optical motion capture system. Data collected from 25 healthy adults demonstrated that the webcam solution exhibited high test-retest reliability, with substantial to almost perfect intraclass correlation coefficients for most joints. Compared with the marker-based system, the webcam-based system demonstrated substantial to almost perfect inter-rater reliability for some joints, and lower inter-rater reliability for other joints (e.g., shoulder flexion and elbow flexion), which could be attributed to the reduced sensitivity to joint locations at the apex of the movement. The proposed webcam-based method exhibited high test-retest and inter-rater reliability, making it a versatile alternative for existing ROM evaluation methods in clinical practice and the tele-implementation of physical therapy and rehabilitation.

Comparison of existing joint orientation parameters and their effect on rock erodibility in dam spillways

Rock mass erosion in unlined spillways causes significant structural damage and necessitates expensive repairs. The rock mass is made up of blocks formed by various arrangements of joint sets. The volume and the protrusion of these blocks, as well as the orientation, opening and roughness of the joints, are all features that can affect rock erodibility. Most of these features are incorporated in parameters developed for rock mass characterization. Three joint orientation parameters are compared in this article using a database containing geological and hydraulic information on scoured spillways. According to the detailed method, data are first classified according to rock quality using the Geological Strength Index obtained with the chart suggested by Marinos and Hoek (GSI chart ). Then, for each GSI chart class, data are distributed according to the damage level, stream power and joint orientation parameter chosen. This study shows that no joint orientation parameter is currently able to accurately represent the effect of joint orientation on erosion of excellent- to poor-quality rock mass. Moreover, this study shows that the GSI chart index is not a rock quality index that completely evaluates rock erosion, as some relevant parameters for evaluating rock erodibility are not considered.