Foot Arch Research Articles

Numerical Simulation Study of the Vibrational Response of Continuous Arch Tunnels under the Action of Overlying Train Loads

With the rapid development of transportation infrastructure in China, continuous arch tunnels passing under existing operational railways are increasingly encountered. This paper primarily investigates the mechanical response patterns of the lining of continuous arch tunnels under the vibrational loads generated by trains traveling on railways. To this end, a three-dimensional finite element model of the dynamic response of continuous arch tunnels under train vibrational loads was constructed using Midas GTS/NX software. This model explores the patterns of acceleration, dynamic displacement, and dynamic strain responses of continuous arch tunnels under the action of moving train loads. The study reveals that under train vibrational loads, the vertical acceleration, vertical displacement, and strain time history curves at various monitoring points in the continuous arch tunnel exhibit vibrational characteristics. The acceleration, vertical displacement, and dynamic strain increase as the train enters, fluctuate within a certain range, and then decrease to zero as the train exits. Under high-speed train loads, the acceleration peak values at the arch feet and outer sidewalls of the left and right tunnels are larger, with a greater peak value difference. The vertical displacement peak values at the arch shoulders and crown are larger, whereas those at the middle partition wall and base slab are smaller. During the process from the train's entry to its exit, the dynamic strain exhibits a trend of initially increasing, then stabilizing, and finally decreasing to zero, all while displaying vibrational characteristics. The strain response on the tunnel side where the train enters is greater than that on the side where it exits.

Mechanism and prevention of “Closed Door” collapse in tunnel construction: A case study

The prevention of “closed door” collapse is crucial for tunnel construction safety and progress assurance. To address the challenge of preventing “closed door” collapse, a study was conducted based on a case of tunnel collapse. This tunnel passes through sections of fractured rock with groundwater development. The main research methods are on-site monitoring and mechanical model calculations. The research findings indicate that weak fractured rock, groundwater, initial support quality issues, long trailing distances, and extensive excavation footage all contributed to the “closed door” collapse. On-site monitoring in the fractured rock section showed the tunnel deformation is high sensitivity to construction disturbances. Even without disturbances, tunnel deformation gradually increases. This contributes about 20% of the total deformation, worsening surrounding rock damage and loosening. Additionally, the initial support exhibits cantilever arch mechanical response characteristics due to excavation of the surrounding rock on one side of its lower part. The mechanical model calculation has verified that under a cantilever arch state, the initial support lacks the bearing capacity to withstand loose load. The continuous deformation of the surrounding rock damages the collapsed body, generating loose load. Excavation of the surrounding rock beneath the initial support arch foot changed the structure from a fixed arch to a cantilever arch, ultimately leading to the joint failure of the surrounding rock-support structure system. This is the mechanism behind the collapse. By combining the convergence confinement method, the influence mechanism of factors such as excavation footage and trailing distance on the “closed door” collapse was further elucidated. Finally, according to the stability evaluation of the collapsed cavity, a strategy of “supporting first and then grouting” is adopted for collapse treatment. Drawing from the understanding of the “closed door” collapse mechanism, the following principles for collapse prevention are proposed: “small excavation footage, ensuring the quality of initial support, short trailing distance, quick support, frequent measurement.”

Effect of arch foot settlement on soil arching in pile-supported embankments under localized surface loading: Numerical damping spring-based trapdoor tests

In most existing trapdoor tests, the supporting structures beneath the arch feet are usually stationary, however, for embankments with flexible or floating piles in deep soft soil areas, piles supporting the arch foot usually settle under vehicle loads, significantly affecting the settlement deformation and load transfer of the embankment. Therefore, A numerical damping spring-based trapdoor model that can account for arch foot settlement is proposed to investigate the effect of arch foot settlement on the soil arching, while comprehensively considering the influence of the interaction among the pile, embankment fill, and soft soil on the evolution of soil arching in a pile-supported embankment. The results show that arch foot settlement on the soil arching differs significantly at different stages: it weakens the soil arching in the initial state and enhances the soil arching in the recovery state but little affects the soil arching in the ultimate state. Moreover, the arch foot settlement significantly reduces the height and stability of the soil arch in relatively high soft soil stiffness conditions, leading to a soil arch that is susceptible to degradation under localized loads. In addition, the arch foot settlement increases the normalized displacement needed for full mobilization of soil arching, resulting in varied levels of mobilization under the same differential settlement.

Conventional vs Augmented Reality-Guided Lateral Calcaneal Lengthening Simulated in a Foot Bone Model.

Acquired adult flatfoot deformity (AAFD) results in a loss of the medial longitudinal arch of the foot and dysfunction of the posteromedial soft tissues. Hintermann osteotomy (H-O) is often used to treat stage II AAFD. The procedure is challenging because of variations in the subtalar facets and limited intraoperative visibility. We aimed to assess the impact of augmented reality (AR) guidance on surgical accuracy and the facet violation rate. Sixty AR-guided and 60 conventional osteotomies were performed on foot bone models. For AR osteotomies, the ideal osteotomy plane was uploaded to a Microsoft HoloLens 1 headset and carried out in strict accordance with the superimposed holographic plane. The conventional osteotomies were performed relying solely on the anatomy of the calcaneal lateral column. The rate and severity of facet joint violation was measured, as well as accuracy of entry and exit points. The results were compared across AR-guided and conventional osteotomies, and between experienced and inexperienced surgeons. Experienced surgeons showed significantly greater accuracy for the osteotomy entry point using AR, with the mean deviation of 1.6 ± 0.9 mm (95% CI 1.26, 1.93) compared to 2.3 ± 1.3 mm (95% CI 1.87, 2.79) in the conventional method (P = .035). The inexperienced had improved accuracy, although not statistically significant (P = .064), with the mean deviation of 2.0 ± 1.5 mm (95% CI 1.47, 2.55) using AR compared with 2.7 ± 1.6 mm (95% CI 2.18, 3.32) in the conventional method. AR helped the experienced surgeons avoid full violation of the posterior facet (P = .011). Inexperienced surgeons had a higher rate of middle and posterior facet injury with both methods (P = .005 and .021). Application of AR guidance during H-O was associated with improved accuracy for experienced surgeons, demonstrated by a better accuracy of the osteotomy entry point. More crucially, AR guidance prevented full violation of the posterior facet in the experienced group. Further research is needed to address limitations and test this technology on cadaver feet. Ultimately, the use of AR in surgery has the potential to improve patient and surgeon safety while minimizing radiation exposure. Subtalar facet injury during lateral column lengthening osteotomy represents a real problem in clinical orthopaedic practice. Because of limited intraoperative visibility and variable anatomy, it is hard to resolve this issue with conventional means. This study suggests the potential of augmented reality to improve the osteotomy accuracy.

Experimental and numerical study of the three-dimensional temperature field in the arch ribs of the reinforced concrete ribbed arch bridge during construction

The unique structural design of an arch ring featuring varying inclination angles for individual segments causes variations in the longitudinal distribution of the temperature field d along the arch axis. This study aims to enhance the understanding of temperature fields in reinforced concrete (RC) arch bridges with diverse arch ring structural configurations during their construction phases. A comprehensive investigation into the three-dimensional distribution pattern of solar-induced temperature fields within arch ribs during the construction of RC ribbed arch bridges was conducted. A field test specifically measuring the temperature distribution across arch rib cross-sections was conducted on-site, involving an RC arch bridge constructed using the cable-stayed cantilever cast in situ method. Analyzing the monitored on-site temperature data revealed the distribution characteristics of temperature fields at the arch foot cross-section under solar radiation. By comparing these findings with international standards, a vertical temperature gradient fitting model for arch rib cross-sections under solar radiation was formulated. Drawing upon meteorological records and solar radiation principles, an adaptive numerical simulation finite element model was developed to depict the temperature field within an arch rib section. This model was rigorously verified. Subsequently, a comprehensive analysis of the three-dimensional temperature field of the arch rib under solar radiation was performed. Additionally, a three-dimensional temperature gradient fitting model was proposed, accounting for the longitudinal inclination of the bridge.

Arches of the foot

Arches of the foot

Arch First and Beam Later Technology: An Accelerated and Safe Construction for Tied Arch Bridges

The Taidong River Bridge, a 115 m tied arch bridge, was opened in 2021 over the Taidong River in Jiangsu, China. Due to the significant role of the Taidong River as a crucial navigation channel for local transportation, construction activities aimed to reduce the duration of river closure. The bridge construction employed the pioneering technique of arch first and beam later without support mechanisms in the river course. This method entailed the integral hoisting of arch ribs via a floating crane, and the tied-arch bridge's longitudinal deformation was temporarily consolidated with tension during construction phases. The investigation analyzes the hoisting point layouts, arch rib limiting devices, structural system transformations implemented, as displacement, and horizontal thrust of the arch foot during the temporarily consolidated tensioning construction stage of the bridge. The research results showed that the arch first and beam later method without support construction adopted in this project demonstrated impressive compliance with the navigation standards stipulated for the Taidong River. In addition, this study proposes a method that combines mechanical calculation formulas with the Midas model to determine the position of the arch rib suspension point and provide theoretical values for temporary consolidation forces during the construction stage. The findings of this study offer valuable practical guidance that can be applied to comparable bridge projects.

Effect of Weight Bearing on Medial Longitudinal Arch of Foot in Healthy Adults

Background: The medial longitudinal arch (MLA) of the foot plays a pivotal role in biomechanical stability and mobility. Understanding its behavior under different loading conditions is crucial for both clinical and sports-related applications. Previous studies have offered insights into the arch's adaptability, yet the impact of gender on this dynamic has remained underexplored. Objective: This study aimed to investigate the differences in medial longitudinal arch height between genders in non-weight bearing (NWB) and full weight bearing (FWB) positions, to ascertain if gender influences arch behavior under various loading conditions. Methods: Conducted at the Biomechanics and Kinesiology Laboratory of Shifa Tameer e Millat University, this cross-sectional study enrolled volunteers aged 18 to 40 years with normal foot arches. Exclusion criteria included history of foot pain, foot anomalies, pregnancy, or menstruation at the time of data collection. Navicular height was measured using Kinovea software (Version 0.9.5), with participants in both NWB and FWB positions. The study received approval from the Institutional Review Board and Ethics Committee of Shifa International Hospital (IRB # 0213-23). Statistical analysis was performed using independent and paired sample t-tests. Results: The study involved equal numbers of male and female participants, with no significant gender-based differences observed in navicular height in NWB (Males: Left Foot 5.17 ± 0.865, Right Foot 5.19 ± 0.675; Females: Left Foot 5.24 ± 0.89, Right Foot 5.39 ± 0.867) and FWB positions (Males: Left Foot 4.73 ± 0.834, Right Foot 4.88 ± 0.846; Females: Left Foot 4.83 ± 0.898, Right Foot 4.80 ± 0.837). Significant reductions in navicular height from NWB to FWB were noted across both genders (p < 0.01). Conclusion: The medial longitudinal arch height significantly changes under weight bearing, displaying a similar pattern of adaptability across genders. This indicates that gender does not significantly influence the biomechanical behavior of the MLA under the tested conditions.

Experimental study on the damage performance and forced response of concrete lining in fault-crossing tunnel

Understanding the adverse effects of tunnel crossing active faults on tunnel structures is crucial for ensuring their safe operation and construction. This paper presents the results of a series of model tests conducted at a scale of 1:40 using a fault sliding test box. Three sets of fault comparison tests were carried out, namely: (1) the tunnel does not cross the fault, (2) the spring stiffness is reduced, and (3) the model is not reinforced. The objective was to study the failure characteristics of tunnels crossing active faults. The findings reveal that when the hanging wall moves downwards, cracks appear on the surrounding rock surface of the hanging wall, specifically above the tunnel lining crossing the fault. The lining is significantly damaged within the range of − 30–+ 30 cm. All points of axial force exhibit an increasing compression trend. The section of axial force and bending moment near the fault fracture surface is notably larger than that far from the fault fracture surface. The safety factor of the entire structure decreases sharply after dislocation, making the tunnel more susceptible to cracking at various locations such as the vault, arch waist, left and right arch feet, and inverted arch. It has been proven that the shear compression of the fracture surface during fault dislocation is the main cause of longitudinal through cracks in the lining. The use of springs with higher stiffness effectively ensures the reciprocating dislocation of the upper and foot walls, with long duration and large displacement, providing a better simulation of the dislocation of active faults.

Treatment for plano-valgus foot in children with subtalar arthroereisis. A review

Plano-valgus foot is a common problem among children and adolescents. The problem is most often noticed in early childhood, as this is the period when the arches of the foot should achieve a normal structure through the disappearance of the fat pad that is present from birth. During this period, the child's skeletal system is very malleable and its remodelling can be considerably influenced by additional factors. This is due to the high amount of cartilage tissue present in a child's skeletal system. Plano-valgus foot can be treated with non-operative methods, such as physiotherapy or the use of orthopaedic supplies, such as suitable orthopaedic insoles. Unfortunately, non-operative treatment is not always sufficient. If physiotherapy does not achieve the expected results, a physician may opt for surgical treatment to restore a correct foot alignment. The most commonly performed plano-valgus foot procedure is subtalar arthroereisis. It is a minimally invasive procedure that takes approximately 10–30 minutes to perform. During the procedure, appropriate implants of various types and sizes are inserted into the tarsal sinus to reduce excessive foot pronation. Studies have shown that the procedure is beneficial to the patient, as it positions the foot correctly and children can return to performing physical activities without experiencing pain and/or rapid muscle fatigue in the foot area. The most commonly used measurements to assess the effects of plantar arthrodesis are those calculated from X-rays, such as Meary's angle, calcaneal inclination pitch angle (CP), talocalcaneal angle (Kite's angle), and surveys using The American Orthopaedic Foot and Ankle Society’s (AOFAS’s) ankle and hindfoot scoring system.

Correlation between Foot Transverse Arch Index and Foot Posture Index in Identifying Foot Arches in Healthy Population

Background: Medial longitudinal arch of foot plays a crucial role on maintaining ankle during weight bearing activities. In previous studies arch index derived from foot print shows a negative correlation with the navicular height. There are no other studies have correlated mathematically derived foot print values with standing arch height measurements with an acceptable equation. This study correlates arch index and foot posture index to identify foot arches. Methods: subjects with high arch have taken for the study. The study type is observational study was done on sample size n=60,foot arch index and foot posture index was evaluated with the samples. Findings: a r- value of 0.333, there is a Negative correlation between Arch index and Foot posture index in low arched foot. There is no significant correlation, and the a r- value of 0.173, there is a low positive correlation between arch index and foot posture index in high arched foot. Interpretation: Among high arched foot and low arched foot, Foot Posture Index and Arch Index is correlated, according to Pearson's correlation, only high arched foot shows low positive correlation between Foot Posture Index and Arch Index. Flatfoot shows negative correlation.

Effects of BOSU Ball Exercises Versus Wobble Board Exercises on Pain and Balance in Individuals with Pes Planus

Background: Pes planus, usually called flat foot is a deformity that causes the medial longitudinal arch to collapseand makes the foot flat to the floor level. Flat feet may be caused by aging, pregnancy, heredity, physiologicalcondition or an injury to the foot ligaments. Weight-bearing exercises are performed on an unstable surface suchas wobble board and BOSU ball as part of the balance board training technique.Purpose: To find out the effect of BOSU ball exercises versus wobble board exercises among individuals with pesplanus.Materials and Methods: A sample of 30 was taken using a navicular drop test on the arch of the foot, NPRS on pain,and Berg balance scale on balance. According to the selection criteria for the study which was divided into twogroups, a BOSU ball with ultrasound (n=15) and wobble board with ultrasound (n=15) were given. Interventionswere given as 6 sessions a week for 2 weeks. The entire process was performed from November 2022 to April 2023.Result: The mean value of BOSU ball exercises at the post-test was found to be higher than the mean value ofwobble board exercises with a p-value of <0.0001.Conclusion: The study concludes that the BOSU ball with ultrasound therapy has a higher positive outcome inmanaging pes planus.

To Study the Effectiveness of Dry Needling on Functional Performance with Plantar Fascitiis

Background: Plantar fasciitis (PF) is a chronic and progressive disease that impairs patients’ quality of life anddaily activities. PF is caused by repeated tissue injury at the origin of the calcaneus’ medial tuberosity. Thesymptoms include Pain expanding from the heel’s medial aspect into the arch of the foot. Pain is frequently worsein the morning, after a period of rest, or after engaging in physical exercise. These signs and symptoms can becomeparalyzing as the illness advances, reducing the individual’s ability to bear weight. According to recent research,the condition should be called fascists because the pathology is more similar to that of tendinosis. The thickness ofthe plantar fascia increases, as does degenerationPurpose: The purpose of the study to determine the effectiveness of dry needling for the subjects with plantarfasciitisMaterials and Methods: 68 subjects in total were chosen based on the inclusion and exclusion criteria. Experimentalgroup (n=34) patients received dry needling of intended sites using a 30 mm needle that was gradually withdrawnafter 15 minutes. The conventional group (n=34) received the Ultrasound therapy was applied at 3.0-MHzfrequency .Patients taken from the five plus hospital. The study period was from December 2022 to March 2023.Results: Statistical analysis of 6 minute Walk test and NPRS examination post values revealed the constantlysignificant differences, With the P value of <0.0001.Conclusion: Dry needling with strengthening exercise was found to be comparatively more effective thanultrasound therapy with strengthening exercise.

Cone-beam computed tomography in the diagnosis of flatfoot deformity: prospective study: a prospective study

INTRODUCTION: Flat deformities are one of the most common pathological changes of the feet. Flatfeet is a disease with high social significance, since it not only affects on the quality of life, but is also an important factor in classification of fitness for military service. The main method of diagnosis of these diseases is radiography of the feet in a lateral projection in the standing position. Despite numerous publications describing various methods for assessing the ratio of the bones of the foot, there is no consensus in the scientific community about the exact criteria for flatfoot and its degrees. At the same time, it is noted that the final conclusion is influenced not only by the method of evaluating the finished image, but also by the method of conducting the study. The construction of modern digital X-ray systems in most cases is not adapted for classical X-ray podography, and the study without special devices and the impossibility of strict adherence to the methodology lead to significant distortions of the results. It follows from this that specialized equipment is required for the diagnosis of flatfoot deformities, which allows developing a unified methodology for conducting research and limiting the possibilities of simulations and aggravations.OBJECTIVE: To determine the possibilities of cone-beam computed tomography in the diagnosis of flatfoot deformities in a standing position with a natural load.MATERIALS AND METHODS: This study included 100 patients underwent examination at the S.M.Kirov Military Medical Academy. All patients were examined using the classical radiography and using the cone-beam computed tomograph (CBCT) «ATRISS» (Electron, Russia). Tomograms were evaluated by two methods: using an averaged image and using a thin slice. The study was conducted by two doctors with the determination of the height and angle of the arch of the foot, followed by an assessment of the degree of flatfoot. Statistics. Statistical analysis was performed using Medcalc software (version 18.2.1). The absolute results of measurements for longitudinal and transverse flatfoot obtained by various methods were compared, as well as the time spent on the study (Wilcoxon and Friedman criteria), the degree of correlation between measurements (Spearman’s criterion), as well as the degree of consistency of the conclusions of two experts to identify longitudinal and transverse flat feet (Kappa-Cohen coefficient). RESULTS: Angle measurements in absolute values did not differ significantly between all the methods used (p=0.1803). There were significant differences between measurements of the height of the arch of the foot between the X-ray method and CBCT (p<0.01). In a comparative analysis of radiography and CBCT, two experts noted a high consistency of research results. CBCT made it possible to perform studies with less time (p<0.01). The effective dose for CBCT is significantly higher than for radiography (p<0.01), but does not exceed 0.12 mSv.DISCUSSION: According to the results of the study, it was found that the effectiveness of CBCT in the diagnosis of flatfoot deformities is not worse than classical radiography. At the same time, the CBCT allows you to avoid positioning errors, stacking and cases of attempted simulation. The effective dose for CBCT allows using the technique as a preventive study. Also, CBCT has a high throughput and allows you to get significantly more information in one scan than with radiography.CONCLUSION: CBCT in a standing position with a natural load is not worse then classical radiography techniques in the accuracy of diagnosis of flatfoot deformities. At the same time, the CBCT has extensive postprocessing capabilities, higher throughput, low radiation load, and also reduces the likelihood of methodological errors and cases of aggravation. CBCT is promising in the consciousness of a universal methodology for measuring and classifying of flatfoot with a more precise formulation of setting points for measuring the angles of the arch and deviation of the hallux.

Study on Numerical Simulation of Surrounding Rock Structure Safety of Urban Underwater Shield Tunnel: A Case in Chongqing

Based on the engineering background of shield construction of a subway section in Chongqing, which needs to pass through a park and there is a lake inside this park, this paper adopts theoretical analysis methods and numerical simulation calculation methods to explore the distribution law of the seepage field and the characteristics of water pressure in lining segments during shield tunneling. The results show that, during the whole excavation of a double-track tunnel with EPB shield, the maximum vertical effective stress is about 4.24 MPa, which is located at the arch foot of the tunnel. The maximum effective stress in the horizontal direction is about 3.61 MPa, which is located on both side walls of the tunnel in the horizontal direction; after the left and right tunnels are excavated in sequence, a “double precipitation funnel-shaped” pore pressure distribution is formed around the tunnel; during the construction of the shield tunnel, the vertical displacement and horizontal displacement of the surrounding rock show an increasing trend and gradually tend to be stable values of 24.09 mm and 25.28 mm; the segment vault has settlement, the maximum settlement is 21.8 mm, the arch bottom has uplift, and the maximum uplift is 24.4 mm. The maximum horizontal displacement of the segment appears on both sides of the arch waist, and the maximum horizontal displacement decreases with the increase of excavation steps; the positive bending moment of the lining segment is mainly distributed on both sides of the arch crown, and the negative bending moment is mainly distributed on both sides of the arch bottom. The axial force of the lining segment is compressive stress, and the maximum axial force is mainly distributed on both sides of the arch waist. The maximum normal shear stress occurs on both sides of the segment arch bottom. The study conclusions provide theoretical foundation and a new guidance for long-term safety evaluation of underwater tunnel structures.

An Emphasis on the Role of Peroneus Brevis to Peroneus Longus Transfer in Progressive Collapsing Flatfoot Deformity

The role of the peroneal tendons in progressive collapsing flatfoot deformity (PCFD), also traditionally known as posterior tibial tendon dysfunction, is likely overlooked and almost certainly understudied. We explored the impact of peroneus brevis (PB) to peroneus longus (PL) transfer in the adult population with flexible PCFD deformities class A1 (flexible hindfoot valgus), B1 (flexible midfoot abduction), and C1 (flexible forefoot varus) as an augmentative measure combined with various bony procedures with proper assessment functionally, clinically, and radiologically. PB to PL tendon transfer poses a simple procedure dealing with muscle imbalance between the medial and lateral columns of the foot. It deals with the new understanding of the PCFD complex as a three-dimensional deformity. It works mainly on the axial plane to limit midfoot abduction and strongly augments the PL acting on the sagittal plane to address the forefoot varus. Finally, to a lesser extent, it deals with the coronal plane of hindfoot valgus, eliminating the primary evertor of the foot (PB) while simultaneously strengthening the PL, which contributes to the medial longitudinal and transverse arches of the foot, therefore decreasing the possibility of lateral column overload commonly caused by the Evans osteotomy through reducing pressure across the calcaneocuboid joint. This procedure is preferably indicated for flexible PCFD deformities class (A1, B1, and C1), yet is contraindicated in neuromuscular deformities with peroneal nerve palsy. Level of Evidence: Level IV.

A rare case of adult-onset spastic paraparesis associated with Klinefelter syndrome

ReportThe rare association of Klinefelter syndrome and the clinical presentation of a late onset chronic progressive spastic paresis.Clinical Presentation and GeneticsAn infertile, 61-year-old man, presented with late adult onset of gait problems, deep muscle pain, and bladder problems. He presented for the first time, years after onset with a spastic paraparesis with high arched feet. His parents had already died, but the patient described high arched feet with his mother. There is no further certain information about the parents. After thorough investigation, an additional X chromosome was found, whereafter the diagnosis of Klinefelter syndrome could be made. Other acquired and genetic causes for spastic paraparesis or hereditary motor neuropathy are excluded.ConclusionThis rare case, together with three other literature reports by Sasaki (Intern Med 58(3):437–440, 2019), Sajra (Med Arh 61(1):52–53, 2007) and Matsubara et al., (J Neurol Neurosurg Psychiatry 57(5):640–642, 1994). suggests that Klinefelter syndrome can be associated with spastic paraparesis, besides the other various neuropsychiatric symptoms that are more commonly described.

Effects of Plantar Fascia Release and the Use of Foot Orthoses Affect Biomechanics of the Medial Longitudinal Arch of the Foot: A Cadaveric Study.

The aim of the study is to evaluate the effect of minimally invasive ultrasound-guided fascial release and a foot orthoses with first metatarsal head cutout on the biomechanics of the medial longitudinal arch of the foot in cadaveric specimens. A cross-sectional study was designed (20 body donors). Anthropometric measurements of the foot, foot posture index, and the windlass test and force were measured in different conditions: unloaded, loaded position, with foot orthoses, after a 25% plantar fascia release and after a 50% release. For the anthropometric measurements of the foot, differences were found in foot length ( P = 0.009), arch height ( P < 0.001), and midfoot width ( P = 0.019) when comparing the unloaded versus foot orthoses condition. When foot orthoses were compared with 25% plantar fascial release, differences were found in foot length ( P = 0.014) and arch height ( P < 0.001). In the comparison with 50% plantar fascial release, differences were found in the arch height ( P < 0.001). A significant interaction between foot orthoses condition and grades was found in the arch height during the windlass test ( P = 0.021). The results indicate that the presence of foot orthoses leads to a significant increase in arch height compared with other conditions. Furthermore, when plantar fascia release is performed, the arch does not exhibit any signs of collapse.

Study of the damage characteristics and corrosion mechanism of tunnel lining in a sulfate environment

Sulfate corrosion is one of the main causes of tunnel lining deterioration. An accurate understanding of the damage characteristics and corrosion mechanism of sulfate-corroded tunnels is the basis for the anti-corrosion design and damage control of the tunnel lining. Based on a project concerning a sulfate-corroded tunnel in the mountainous area of Southwest China, this study conducted a field investigation and laboratory tests and, combined with existing research data, summarized the damage characteristics and corrosion mechanism of this type of tunnel and proposed the characteristic corrosion state of tunnel lining in a sulfate environment. The results show that 1) sulfate corrosion led to leakage, surface spalling crystallization, and strength loss, and the corrosion typically occurred at the arch waist and arch foot. 2) Physical and chemical corrosion occurred in the tunnel lining, and the corrosion products included sodium sulfate, calcium carbonate, gypsum, ettringite, and thaumasite. 3) In China, this type of tunnel is mainly located in the Southwest and Northwest, and its lining is in a special state of “one-sided accelerated corrosion.”

Technical note: A volumetric method for measuring the longitudinal arch of human tracks and feet.

Fossil footprints (i.e., tracks) were believed to document arch anatomical evolution, although our recent work has shown that track arches record foot kinematics instead. Analyses of track arches can thereby inform the evolution of human locomotion, although quantifying this 3-D aspect of track morphology is difficult. Here, we present a volumetric method for measuring the arches of 3-D models of human tracks and feet, using both Autodesk Maya and Blender software. The method involves generation of a 3-D object that represents the space beneath the longitudinal arch, and measurement of that arch object's geometry and spatial orientation. We provide relevant tools and guidance for users to apply this technique to their own data. We present three case studies to demonstrate potential applications. These include, (1) measuring the arches of static and dynamic human feet, (2) comparing the arches of human tracks with the arches of the feet that made them, and (3) direct comparisons of human track and foot arch morphology throughout simulated track formation. The volumetric measurement tool proved robust for measuring 3-D models of human tracks and feet, in static and dynamic contexts. This tool enables researchers to quantitatively compare arches of fossil hominin tracks, in order to derive biomechanical interpretations from them, and/or offers a different approach for quantifying foot morphology in living humans.