Fracture Depth Research Articles

Investigation of fracture properties and microbially induced calcite precipitation (MICP) restoration in coal mining areas within the diverse Terrain of Northern Shaanxi, China

The complex and diverse nature of coal mining sites, including different landforms and working conditions, presents challenges for rehabilitation efforts. To address this, we conducted a comprehensive experimental study focusing on microbially induced calcium carbonate precipitation (MICP) remediation, considering the fracture characteristics of coal mining sites. The MICP-restored samples were subjected to confined/unconfined compressive strength, uniaxial/triaxial permeability, and souring tests to assess their restoration efficacy. The results showed that under similar mining conditions, the average depth of parallel fractures was 0.185 m for loess ridges, 0.16 m for the valley, and 0.146 m for the blown-sand region, while the average depth for boundary fractures was 0.411 m for loess ridges, 0.178 m for the valley, and 0.268 m for the blown-sand region. Notably, parallel fractures showed negligible filling in all landforms, whereas boundary fractures in the blown-sand region were completely filled with wind-deposited sand. The valley landform was filled with alluvium and wind-deposited sand, whereas the loess landform was filled with wind-deposited sand and loess. MICP-restored soil samples in all landforms achieved a strength comparable to remolded fracture-free soil samples. Across all landforms, the maximum permeability coefficient of MICP-restored soil samples closely matched that of remolded fracture-free soil samples. Under similar topographic and rainfall conditions MICP restorations scoured 31.3 g on blown-sand region, 19.3 g on loess ridges, and 17.6 g on valleys. These research findings provide an experimental foundation for MICP repair of coal mining ground fractures.

ENHANCING FORMABILITY OF AA6061 IN INCREMENTAL SHEET FORMING: EXPLORING PARAMETER EFFECTS ON FRACTURE DEPTH

AA6061's high strength and strain rate sensitivity in Incremental Sheet Forming (ISF) demand precise parameter control to prevent early fractures, especially at steep wall angles. Tool diameter influences the distribution of deformation forces, while spindle speed, step depth, and feed rate control the rate and extent of material deformation, collectively impacting the forming. This paper investigates the effect of these process parameters on the formability in terms of fracture depth. A statistical analysis is performed to identify the significant factors affecting forming depth. The main effect plot suggests that except the spindle speed, all three process parameters influence forming depth. However, the interaction plot reveals a more complex relationship, where step depth has a stronger effect on fracture depth, particularly at higher feed rates. These findings indicate that the interplay between these factors is crucial for determining optimal process parameters, where nearly 10% of increase in forming depth was achieved.

Prevalence of femoral condyle injuries in the setting of tibial plateau fractures

BackgroundTibial plateau fracture patterns are influenced by the direction and energy of the impact, and the bone quality. Associated articular femoral injuries can result from the same impact but are insufficiently studied. This study quantifies the prevalence of three distinct articular femoral condyle injuries: (1) impaction fractures, (2) contusions, and (3) condyle fractures. For impaction fractures we assessed the depth, width, length, and surface area. MethodsWe retrospectively reviewed patients who had undergone surgery for a tibial plateau fracture in a tertiary trauma center. Two fellowship-trained radiologists analyzed preoperative CT scans for associated femoral condyle injuries. We defined (1) impaction fractures (depressions ≥ 1.5 mm) with a sclerotic band, a fracture line, or both; (2) contusions (depressions < 1.5 mm) with a sclerotic band; and (3) condyle fractures as sub- or osteochondral fractures. ResultsWe identified 149 patients (62 male) with a tibial plateau fracture with a CT scan available. The overall prevalence of articular femoral condyle injuries was 26% (n = 39). The prevalence of impaction fractures was 9.4% (n = 14), of contusions 14% (n = 21), and of condylar fractures 3.0% (n = 4). Factors associated with a higher prevalence of femoral condyle injury were younger age (p = 0.029), male sex (p = 0.014), and absence of comorbidity (p = 0.005). The mean depth of impaction fractures was 2.3 mm (SD: 0.78; range 1.6 to 4). ConclusionConcomitant articular femoral condyle injuries occur in one out of four patients with a tibial plateau fracture. Although most femoral injuries were subtle, and none underwent surgical treatment, they might harbor information regarding the likelihood of future joint degeneration and knee instability.Level of evidence: IV.

Numerical study of influence of karst fracture water on heat transfer performance of borehole heat exchanger

Groundwater flow within karst fractures can significantly enhance the heat exchange efficiency between a borehole heat exchanger (BHE) and the surrounding rock. The development of artificial fractures to intensify heat transfer between the BHE and rock has emerged as a promising direction in geothermal exploration. This study presents a three-dimensional finite element simulation model that integrates fracture flow with BHE heat transfer, accounting for various characteristics of horizontal fractures. Data analysis was conducted using range analysis and multi-criteria comprehensive evaluation, based on the principles of orthogonal experiments. The results indicate: (i) Fracture water flow substantially improves BHE heat transfer performance in summer, with even the lowest-performing configuration in the orthogonal test showing a 5.36 % increase in heat transfer per unit length of the BHE (HPLU) compared to the natural control group without fractures; (ii) The influence of different fracture characteristics on BHE heat transfer performance follows this order: fracture water velocity > fracture aperture > fracture depth > fracture flow direction > fracture water temperature; (iii) The optimal configuration enhances HPLU by 16.95 % over the natural control group, demonstrating that developing well-designed artificial fractures in karst regions can substantially improve BHE heat transfer efficiency.

Use of a percutaneous bone fiducial screw for elevating simple closed depressed skull fractures: illustrative cases.

Depressed skull fractures in infants often present as "ping-pong ball" fractures with inward buckling of the calvarium, secondary to trauma. Management varies widely, and few concrete guidelines exist in the literature to guide decision-making when choosing a methodology for fracture elevation. The authors present two cases of attempted depressed skull fracture elevation with traction on a percutaneously placed bone fiducial screw, followed by a review of the literature, in order to further investigate the factors considered when selecting an intervention. An 8-month-old female and a 10-month-old male presented with a right parietal depressed skull fracture. Both underwent attempted fracture elevation with a self-tapping screw anchored into the skull. The authors directly elevated the fracture with the screw technique in the 8-month-old female patient. The 10-month-old male had persistent depressed skull deformity; thus, the authors extended the incision for a standard craniotomy for depressed skull fracture elevation. Percutaneous screw placement may be considered an option in the spectrum of treatment strategies for select patients with depressed skull fractures. Consideration of patient age, skull thickness, and depth of skull fracture can assist with the choice of treatment strategy and the preoperative prediction of the likelihood of fracture elevation success with this technique. https://thejns.org/doi/10.3171/CASE23742.

Numerical and experimental study of three-layered Al 1050/Mg AZ31B/ Al 1050 sheets formability considering strain and stress conditions through single point incremental forming

This article examines the formability of 3-layer Al 1050/Mg-AZ31B /Al 1050 sheets experimentally and numerically. Mg AZ31B, with its high strength-to-weight ratio, and Al 1050, with its formability and lightweight, are attractive industrial metals. In the experimental method, the forming limit diagram (FLD), the Forming limit angle (FLA), and the fracture depth were investigated for the 3-layer and base samples with two pyramid and cone geometries. The results showed that the ductility in the cone geometry is higher than that of the pyramid. Also, by comparing the FLD of the 3-layer sample to the base sample, the results showed that the formability of the 3-layer sample increased compared to the Mg-AZ31B base sample. In contrast, the formability decreased compared to the base sample of Al 1050. Numerical studies for predicting the FLD using the SPIF method were carried out using Abaqus software. The numerical techniques considered the second deviation minor strain (SDMIS), second deviation effect strain (SDEF), second deviation thickness (SDT), and second deviation major strain (SDMS). The results showed that the highest accuracy occurred for the SDT method compared to other numerical methods. To remove the effect of the strain path on the numerical analysis for predicting the FLD (from the stress analysis method), a second deviation of von Mises stress (SDVMS) was used. By examining the results, it was found that the results of numerical methods considering stress could be highly accurate.

Monitoring stress-induced brittle rock mass damage for preventative support maintenance

Stress-induced brittle fracturing near an excavation boundary results in a volume increase, known as bulking. Excessive bulking places added demand on the rock support, which, if not detected and addressed through preventative support maintenance (i.e., proactively added reinforcement), can cause the support to fail, leading to a safety hazard and costly production delays for underground mining operations. For caving mines, these project risks are exacerbated during cave establishment due to the large abutment stress from undercutting that redistributes and concentrates stresses near excavations critical for production. This paper reports the findings from research conducted to develop and improve geotechnical monitoring practices to support preventative support maintenance in deep mining operations. This research uses a unique geotechnical monitoring database collected for the Deep Mill Level Zone panel cave mine. The data was collected across a large footprint during the mine's ramp-up period and represents an initial step toward best practices for data collection at cave mines operating in high-stress environments. Borehole camera surveys supplemented by multi-point borehole extensometers have been used to determine the depth of stress fracturing in pillar walls as a function of the distance away from the undercut. Convergence measurements and LiDAR scanning are used to characterize the corresponding rock mass bulking. The results show that the interpretation of monitoring data can be used to identify the long-term depth of stress fracturing and bulking trends in response to undercut advances. These show that direct measures of stress-induced fracturing damage provide an early indication of excavations vulnerable to bulking and that LiDAR scanning is an effective method for capturing the onset of bulking and anticipating local areas likely to experience greater deformation demand as bulking progresses. Proactive and strategic geotechnical monitoring based on the long-term depth of stress-induced fracturing trends is proposed to assist with preventative support maintenance practices.

Theoretical stability of ice shelf basal crevasses with a vertical temperature profile

Abstract Basal crevasses threaten the stability of ice shelves through the potential to form rifts and calve icebergs. Furthermore, it is important to determine the dependence of crevasse stability on temperature due to large vertical temperature variations on ice shelves. In this work, considering the vertical temperature profile through ice viscosity, we compare (1) the theoretical crack depths and (2) the threshold stress causing the transition from basal crevasses to full thickness fractures in several fracture theories. In the Zero Stress approximation, the depth-integrated force at the crevassed and non-crevassed location are unbalanced, violating the volume-integrated Stokes equation. By incorporating a Horizontal Force Balance (HFB) argument, recent work showed analytically that the threshold stress for rift initiation is only half of that predicted by the Zero Stress approximation. We generalize the HFB theory to show that while the temperature profile influences crack depths, the threshold rifting stress is insensitive to temperature. We compare with observations and find that HFB best matches observed rifts. Using HFB instead of Zero Stress for cracks in an ice-sheet model would substantially enlarge the predicted fracture depth, reduce the threshold rifting stress and potentially increase the projected rate of ice shelf mass loss.

Study on the early warning of cracking and water inrush risk of coal mine roof and floor

Microseismic monitoring has proven to be an effective approach for detecting and preempting water inrush incidents within mining operations. However, challenges persist, particularly in terms of relying on a singular early warning index and the complexities involved in quantification. In response to these obstacles, a dedicated investigation was undertaken against the backdrop of mining activities at the 11,023 working face of Paner Coal Mine. Primarily, a novel methodology for categorizing the roof and floor into distinct zones was established based on the vertical distribution of microseismic events. Furthermore, this study delves into the dynamic evolution of key source parameters, such as microseismic energy, apparent stress, and apparent volume, amidst mining disturbances, enabling a comprehensive evaluation of the risk associated with roof and floor cracking, as well as potential water inrush incidents. A groundbreaking approach to early warning was proposed, operating on three pivotal dimensions: the depth of fractures, the intensity of fractures, and the likelihood of water inrush. Through rigorous validation during mining operations at the 11,023 working face, the efficacy was substantiated. Ultimately, the achievements offer invaluable insights and practical guidance for the advancement and implementation of water inrush early warning systems in coal mining contexts.

Investigation on tribological behaviors of a novel generation polymer-coated ceramsite particle for fracturing

During fracturing, proppant particles can create favorable pathways for shale gas production. To solve the problem of low production efficiency of shale gas, a new polymer coated particle was prepared by experiment. And its mechanical properties were tested and tribological properties were studied under different speeds, loads and medium states. The results show that the new polymer coated particles have excellent tribological and mechanical properties. The friction coefficient between proppant particles and fracture surface decreases with increasing velocity. In addition, the new proppant particles have excellent hydrophobicity under lubricating conditions, indicating that the proppant has excellent migration efficiency. When proppants just pumped into the fracture, it can reach the fracture depth quickly. In addition, the friction coefficient between proppant particles and fracture surface gradually increases with the increase of load. It is further proved that when the proppant particles enter the fracture, the friction coefficient increases due to the extrusion of the fracture, and the reverse displacement can be effectively reduced. This research has important theoretical and practical engineering application value for improving the efficiency of shale gas stimulation.

Experimental Study on the Crack Concrete Repaired via Enzyme-Induced Calcium Carbonate Precipitation (EICP).

A low-carbon and environmentally friendly EICP method for repairing concrete cracks is presented to prolong the service life of concrete. In this study, we took concrete as the research object and quartz sand as the filling medium and employed the EICP injection method to repair concrete cracks. The internal repair effect of EICP on concrete cracks was evaluated with a combination of ultrasonic and compressive strength tests. The concrete repair mechanism of EICP was identified with a combination of EDS, XRD, and SEM tests. The results indicate that with an increase in the fracture depth, the ultrasonic sound time of the crack specimen increased gradually, and the ultrasonic wave transit time value of the crack specimen decreased significantly after EICP repair. After repair, the compressive strength rose. The highest compressive-strength recovery rate of a 0.3 mm wide specimen is 98.41%. The calcium carbonate crystal formed using EICP is vaterite. The probability density function model of the Laplace distribution was constructed, which showed good applicability and consistency in the ultrasonic sound time and compressive strength measured via experiments. The formed calcium carbonate crystals can be tightly and evenly attached to the cracks with the EICP injection repair method, resulting in a better repair effect.

Comparative study on mechanism of hydrogen embrittlement of Fe–18Mn-0.6C twinning-induced plasticity (TWIP) steel subjected to friction-stir welding (FSW) and tungsten inert-gas (TIG) welding

In present study, we investigated the effect of welding technique on resistance of hydrogen (H) embrittlement in Fe–18Mn-0.6C (wt.%) twinning-induced plasticity (TWIP) steel by using an electrochemical H-charging, thermal desorption spectroscope, and electron microscope. The friction-stir welding (FSW) specimen was less sensitive to H embrittlement relative to base metal and tungsten inert-gas (TIG) welding specimens by differences in microstructure and deformation mechanism. During H-charging of the FSW specimen, numerous dislocations/Σ3 boundaries reduced H diffusion into specimen interior, causing shallowest depth of brittle fracture. In contrast, the depth of brittle fracture in the H-charged TIG specimen was much larger due to rapid H diffusion by decreased grain boundaries including Σ3 annealing twin boundaries. During tensile deformation, the H-charged FSW specimen underwent the reduction in stress concentration by inactive TWIP as well as strong resistance of boundary decohesion. It was because of alleviation of H-enhanced localized plasticity (HELP) mechanism, leading to suppression of H-induced crack growth. Conversely, the H-charged base metal and TIG specimens revealed large stress concentration by active TWIP and weak boundaries owing to strong effects of HELP + H-enhanced decohesion (HEDE) mechanisms, exhibiting rapid H-induced crack propagation.

Deterioration mechanisms of tuff with surface fractures under freeze–thaw cycles

In practical engineering, the development of surface cracks is one of the most important reasons for the destruction of the rock mass, and the development of complex morphology fractures on the rock mass surface significantly influences rock mass mechanics. This paper addresses the freeze–thaw damage issue in rock mass containing surface fractures in cold regions. Tuffs and a control group are selected as research samples, with the control group being prefabricated surface jointed specimens with an inclination angle of 70° and a fracture depth ratio d (crack depth) /t (sample width) of 0.26. The study analyzes the mass, wave velocity loss, macro-microcosmic fracture damage morphology, and mechanical properties of the two specimen groups through laboratory freeze–thaw cycle tests, uniaxial compression tests, and scanning electron microscopy examinations. The results show an overall decrease in mass, wave velocity, and uniaxial compressive strength as the cycle number increases, with the prefabricated jointed group samples showing more significant changes. However, the two specimen groups exhibit different macroscopic failure fracture states. In addition, scanning electron microscopy images illustrate that after freeze–thaw cycles, the large rock mass particles break into smaller fragments, resulting in looser particle arrangements and a transition from initial surface cementation to point contact., which weakens the compressive strength of the rock mass. The paper also explains the mechanism of the diminishing impact of freeze–thaw cycles on the strength of the rock mass after a certain number of cycles. The research outcomes hold significant reference value for engineering construction in cold regions.

Unveiling damage mechanisms of SiC fiber-reinforced titanium matrix composites through ultrasonic scratching

SiCf/Ti composites are increasingly being utilized in the aerospace field due to their excellent performance. However, during the application of this material, issues such as fiber fracture and debonding often occur during processing. Ultrasonic vibration-assisted machining technology avoids the waste of cutting fluid and its environmental impact in traditional production, making it widely used in the ultra-precision and environmentally friendly processing of composite materials. This study explores the damage formation mechanism during material removal using diamond scratching. A comparison was made between the specific energy and morphology of ultrasonic scratching and conventional scratching, and a model for fiber fracture depth was established. The results indicate that conventional cutting leads to fiber bending and crushing, with bent fibers causing deformation to the matrix, which further affects the fibers behind. EBSD results confirm that fiber bending deformation affects the microstructure changes in the matrix. Under ultrasonic scratching, scratching force and specific energy decreased by 25% and 50%, respectively, compared to conventional scratching. This effectively reduces the deformation of fibers on the matrix during cutting and enhances the tool's ability to shear and remove fibers. CT analysis of the subsurface showed that under ultrasonic scratching, the maximum decrease in fiber fracture depth was 13% compared to traditional methods. This study guides the clean and low-damage machining of SiCf/Ti composites.

Pediatric ping-pong skull fractures treated with vacuum-assisted elevation.

Depressed ("ping-pong") skull fractures can be treated by different means, including observation, non-surgical treatments, or surgical intervention. The authors describe their experience with vacuum-assisted elevation of ping-pong skull fractures and evaluate variables associated with surgical outcomes. The authors present a retrospective review of all ping-pong skull fractures treated with vacuum-assisted elevation at the Children's Hospital of Orange County in 2021-2022. Variables included patient age, mechanism of injury, fracture depth, bone thickness at the fracture site, and degree of elevation. Seven patients underwent vacuum-assisted elevation of ping-pong fractures at thebedside without the use of anesthesia. Fractures caused by birth-related trauma were deeper than those caused by falls (p < 0.001). There was no significantdifference between groups in bone thickness at the fracture site (2.10mm vs 2.16mm, n.s). Six of the seven patients experienced significant improvement in fracture site depression, with four displaying a complete fracture reduction and two displaying a significant reduction. The degree of fracture reduction was modestly related to the depth of fracture, with the two deepest fractures failing to achieve full reduction. Age appeared to be related to fracture reduction, with the lowest reduction observed in one of the oldest patients in this sample. No complications were observed in any patient other than temporary mild swelling at the suction site, and no re-treatment or surgery for the fractures was required. Vacuum-assisted elevation of ping-pong skull fractures is a safe and effective noninvasive treatment option for infants that can be used under certain circumstances. The procedure can be done safelyat the bedsideand is a relatively quick procedure.Itavoids the need for open surgical intervention, anesthesia, or hospital admission, andcan lead to excellent outcomes.

Surface crack effect on frequency and vibration mode switching of solar-powered aerospace structures

In the engineering design of modern wing panels and their optimal control system, the first step is to find and predict their dynamic characteristics. These characteristics are dependent on material properties, panel geometry, and boundary conditions. In addition, possible fracture existence, imperfections and environmental conditions may unpredictably change the frequency and modes shape of the panel and then the parameters of a control system. In the present paper, the effect of surface fracture depth and orientation on frequency and vibration mode switching of perovskite solar cells-based aircraft wing panels is investigated for the first time. The PSC (perovskite solar cell) panel is made of a polymer substrate reinforced with even-distributed graphene platelets (GPLs) and thin solar layers to enhance the overall electromechanical performance of the whole structure. Equations of motion of the panel are obtained by the Hamilton approach based on the properties of Reddy's third-order shear deformation theory and linear components of the Green-Lagrange strain tensor. The novel aspect is a line-spring model of surface crack by Cartmell et al. adapted to the model of the PSC panel under consideration. The discretization of the established equations of motion for the cracked panel is carried out by the element-free IMLS-Ritz method with mesh-free features. Validation of the obtained solutions is carried out by comparisons with results from previous studies for cracked laminated plates.First, material and geometric properties effect on vibration characteristics of the PSC structure was investigated. Next, partial surface crack depth and orientation angle are examined to show changes in frequency and vibration modes shape of the panel. It is shown, that there is a mode swapping between the second and third modes when transitioning from an intact panel to a cracked one. As the crack length increases, higher-order mode variations become more noticeable, potentially leading to their swapping or the excitation of new ones. Additionally, the findings demonstrate that the surface crack orientation angle significantly impacts the higher-order modes of the panel. When the orientation angle is 90°, the first six modes align with those of the intact plate. Mode shapes and frequency shifts are significant for crack orientation angles between 0° and 90°.

Hydraulic fracturing simulation of concrete dam integrating intelligent crack detection and refined modeling methods

Concrete dams are prone to cracks during construction and operation process. Cracks on the upstream surface may induce the risk of hydraulic fracturing, thereby significantly reducing the safety of dam structure. Nevertheless, image processing technology, non-destructive testing technology and structural performance analysis technology with cracks are in a relatively independent state, leading to difficulties in analysis of actual cracks combined with numerical simulations. This paper proposes a novel approach for combination of intelligent identification technology and refined finite element method (FEM) for modeling and simulating the hydraulic fracturing resistance of the actual crack in concrete dams. With image processing technology and non-destructive testing technology, direction and depth of actual cracks are identified and extracted, then the 3D geometric model of actual cracks is generated. The refined model with the identified actual crack is constructed by the node projection strategy. This approach is used to assess the hydraulic fracturing resistance of the concrete dam with actual cracks in the alpine region. The results demonstrate that the critical crack depth of hydraulic fracturing is 12.93 m, and the opening width is 1.01 mm, which is 2.53 times the limit value for Class D cracks in the code (DL/T5251–2010). The refined modelling method based on actual crack detected on site can accurately evaluate the crack state compared to the conservative code.

Improvement of the methodology for calculating the expected drilling speed with PDC chisels

Purpose. Determination of the dependence of the depth of penetration of the PDC cutter into the bottom hole rock, taking into account its geometric parameters and spatial placement in relation to the destroyed array. Methodology. The tasks were solved by a comprehensive research method, including analysis and generalization of literary and patent sources, conducting theoretical research, which consists in solving the theoretical problem of the impact of a superhard circular cutter on an elastically fragile mountain range, using computer and mathematical modeling methods. Findings. A simplified expression has been obtained that allows taking into account the features of the PDC cutter with sufficient accuracy for engineering calculations when determining the depth of its penetration into the bottom hole rock. A method is proposed for calculating the depth of fracture in one revolution of a diamond carbide cutter PDC into the rock of the bottom of the well. The patterns of destruction by the proposed diamond-hard-alloy PDC chisel of a rock mass at the bottom of the well from the parameters of the drilling regime and the hardness of the drilled rocks have been established. Originality. For the first time, the dependence has been obtained of the influence of the geometric parameters of the shape of a single diamond-carbide PDC cutter and its spatial placement in the body of the bit matrix on the magnitude of the technological parameters of drilling a well, and their effect on the nature of the destruction of the array PDC cutter. Practical value. A technique for determining the depth of penetration of a single PDC cutter is proposed, the use of which will allow predicting the mechanical speed, depending on the geological and technical conditions of drilling wells. And taking into account the abrasive properties of rocks, it is possible to reduce the wear of the bits, and therefore the amount of necessary rock-crushing tools for the entire volume of drilling operations during the construction of the well.

How to Reduce Inferomedial Orbital Wall Fracture Using a Navigation System: Tips and Pearls.

The orbit is a confined space with a defined bony structure. Bony protrusion into the ethmoid or maxillary sinuses by the blowout fracture can displace orbital tissues, including rectus muscles and adjacent fascial septae. Especially, reconstructing the orbit's floor and medial wall can be challenging when the inferomedial strut or posterior bony ledge is affected, leading to a loss of critical anatomic landmarks and support. Correctly positioning an implant in the precise anatomic location can be challenging. Recent updates to the navigation system have addressed this issue. Despite its early application, using a navigation system in these orbital fractures advances plastic surgeons in a way that has more confidence and accuracy in surgical planning. The video demonstrates how these 2 can be combined in an operating room. Intraoperatively, the authors check the superior, anterior, and posterior ends of the medial wall fracture and the posterior end of the floor fracture. A single orbital implant was trimmed and reshaped to match defect measurements. The implant placement was meticulously executed to repair the fracture while ensuring the inferior oblique muscle was not injured. After confirming the correct placement of the implant, it was secured to the inferior orbital rim using a single screw. Depending on the medial orbital wall fracture depth or degree of soft tissue herniation, the authors used an artificial dermal matrix or trimmed absorbable mesh plate to cover the uppermost part of the medial wall fracture to prevent postoperative enophthalmos. Finally, a forced duction test was performed. Our study shows that navigation-assisted inferomedial orbital wall reconstruction using materials readily available in the market is safe and effective.

Level evaluation of concrete dam fractures based on game theory combination weighting-normal cloud model

Hazard evaluation of concrete dam fractures is vital for safe operations. The width (S1), length (S2), and depth (S3) of fractures are adopted as the assessment index, and the game theory combination weighting-normal cloud model is introduced. The normal cloud model of certain dam fractures is subsequently established. The weight coefficients of each index are calculated using game theory combination weighting, and the certainty degree of each index is determined using the cloud model. Finally, the hazard levels of the concrete dam fractures are judged. The proposed model solves the fuzziness and randomness of different indexes; the conclusions demonstrate that the model is feasible for the hazard assessment of concrete dam fractures, and its accuracy is very high; therefore, a new approach can be provided for future hazard-level assessments of concrete dam fractures.