Foot Arch Research Articles

Influence of Ventilation Parameters on Gas Transportation Patterns in Long Highway Tunnels and Sustainable Development of Ventilation Systems

In order to study the influence of ventilation parameters on gas movement in large sections of highway tunnels, a mathematical model of gas movement in tunnels is established based on the Yijin Expressway’s Kahaluo No. 1 three-lane tunnel project in Sichuan Province, by using Fluent numerical simulation software to simulate gas tunnel construction. The space–time distribution characteristics of the gas concentration in tunnel construction are obtained, and the influence of ventilation parameters on gas movement is analyzed, the ventilation parameters of the tunnel construction site were optimized. The results show that after ventilation for 20 min, the flow field in the tunnel gradually developed and stabilized, and the gas concentration developing area finally extended to the 45 m position behind the working face, and the gas in the 9 m area behind the face mainly accumulated at the different side of the arched feet of the air duct. Ultimately, the internal flow field structure of the tunnel is mainly composed of a vortex zone (within 10 m in front of the tunnel), a development zone (10–50 m in front of the tunnel), and a stable zone (50–200 m in front of the tunnel). Under the background of the project, the optimal ventilation parameters are as follows: wind velocity 12 m/s, duct diameter 2.0 m, distance from outlet to working face 8 m, and distance from outlet to secondary lining trolley 24 m. According to the optimal ventilation parameter combination, the ventilation system of Cahalo No. 1 tunnel was optimized. It was found that the gas concentration in the tunnel decreased obviously with the increase in ventilation time. The above research further improves the gas tunnel ventilation study, which is of great significance in guiding the site to optimize the ventilation system and guaranteeing the sustainable development of the tunnel ventilation system.

Numerical Study on Soil‐Arching Behavior in Pile‐Supported Embankments With Pile Settlement by Developed Damping Spring‐Based Trapdoor Model

ABSTRACTSoil arching is one of the main mechanisms for load transfer in pile‐supported embankments, and the soil arching evolution patterns varied significantly depending on fill heights, pile spacings, pile stiffness, and soil stiffness. However, research on the effect of pile settlement on soil arching is relatively scarce, and most studies still use the traditional trapdoor test with a fixed arch foot to examine the soil arching. Therefore, this study establishes numerical models of a damping spring‐based trapdoor that considers pile settlement, and through 52 sets of spring‐based trapdoor tests and 1 set of reference tests, it systematically investigates the effects of various factors such as pile–soil stiffness ratio, fill height, and pile spacing on the soil arching under pile settlement conditions. The research results show that reducing the pile–soil stiffness ratio will reduce differential settlement between piles and soil, but it will exacerbate overall settlement. The stiffness ratio has a significant impact on soil arching: appropriately reducing the pile–soil stiffness ratio will help to recover fill deformation and suppress the formation of passive soil arch; increasing the stiffness ratio will enhance the stability of the soil arching. In addition, when the soft soil stiffness ks is low, pile settlement helps to enhance the soil arching, and the enhancement effect becomes more significant with an increase in fill height H and pile spacing S/a. When ks is high, pile settlement weakens the soil arching, which intensifies with an increase in fill height but weakens with an increase in S/a.

Transspinal stimulation downregulates flexion reflex pathways during walking in healthy humans.

The phase-dependent modulation pattern of the tibialis anterior (TA) flexion reflex was characterized during treadmill walking while transspinal stimulation was delivered at 15, 30, and 50 Hz above and below paresthesia in healthy participants. The flexion reflex was elicited following medial arch foot stimulation with a 30 ms (300 Hz) pulse train. During treadmill walking, the flexion reflex was evoked in the right leg every 3 to 5 steps, and stimuli were randomly dispersed across the step cycle that was divided into 16 equal bins. For each participant, condition and bin of the step cycle, the flexion reflex was measured as the area of the linear EMG envelope starting 20 ms after the end of the pulse train up to 200 ms and was normalized to the maximum locomotor TA EMG activity. The unconditioned flexion reflex was modulated in a phase-dependent manner. Transspinal stimulation, regardless frequency, or intensity produced pronounced flexion reflex depression during walking that coincided with an unchanged slope and intercept, computed from the linear relationship between the flexion reflex and background EMG activity. These findings suggest that transspinal stimulation above and below paresthesia intensities at 15, 30, and 50 Hz downregulates the flexion reflex. Based on our recently reported absent effects on the soleus H-reflex under similar conditions and our current findings we propose that transspinal stimulation downregulates flexion and not extension reflex pathways. More research is needed to delineate whether similar neuromodulation effects are present in flexion and extension reflexes after spinal cord injury in humans.

Research on the influence of curtain grouting parameters on the stability of tunnel surrounding rock and lining structure under the action of local high water pressure

Choosing the reasonable and economical grouting parameters is crucial for controlling the seepage field of surrounding rock and tunnel stability. This paper adopted the fluid–solid coupling theory based on FLAC3D to establish numerous simulations on the stability of surrounding rock and lining structure in karst tunnels under the different grouting conditions. The influences of grouting layer thicknesses and their permeability coefficients on the mechanical behaviors of lining structure, seepage, and stress properties of surrounding rock were investigated. The results show that with the increase of grouting thickness and its ratio of permeability, the maximum flow velocity and flow rate per liner meter in surrounding rock, the bending moments and axial forces, and the horizontal and vertical displacements of the lining structure all exponentially decrease, but safety factors at different positions of the lining structure first rapidly and then slowly increase. The changes in safety factor and uplift displacement at the inverted arch are more significant, and the minimum safety factor occurs at the left arch foot. As the grouting thickness and its ratio of permeability increase, the plastic zone range in surrounding rock decreases and expands, respectively. Through considering the improvement effect and economy of grouting comprehensively, choosing a grouting layer thickness of 7–9 m and a ratio of permeability of 20–50 is an ideal configuration parameter to ensure the stability and safety of karst tunnels under the conditions of this paper. The research results could provide references for choosing the reasonable grouting parameters in karst tunnels.

Insoles in the treatment of pes planovalgus : A prospective, randomised, double-blind, placebo-controlled comparative trial of sensomotoric and supportive insoles

In adults, flexible symptomatic flat foot is treated conservatively with supportive foot orthoses. Sensorimotor foot orthoses, however, are controversial due to insufficient data. Comparison of the effectiveness of sensorimotor and supportive foot orthoses in adults. In 73patients, in addition to foot gymnastics, supportive, sensorimotor or placebo insoles were compared over 3measurement points during 1 year as part of adouble-blind, prospective, randomised placebo-controlled clinical trial using Numeric Rating-Scala, the Foot and Ankle Disability Index, as well as pedobarography and valgus index. The statistical analysis was performed using ANOVA with repeated measures. The valgus index increased significantly with supportive foot orthoses. In the follow-up, the foot contact area was only significantly reduced with sensorimotor foot orthoses in static and dynamic measurements. Supportive foot orthoses led to afaster reduction in pain, but withoutreducing the contact area of the foot. There were no relevant differences in functionality. The reduction of the contact surface in combination with sensorimotor foot orthoses shows the potential for muscular addressing of the flexible flat foot. There were no disadvantages compared to other treatments. Supportive foot orthoses led to afaster reduction in subjective complaints, but appear to weaken the muscles supporting the arch of the foot. In the longer term, consistent foot muscle training also appears to be effective, as wearing placebo foot orthoses also led to an improvement in subjective well-being without significant biomechanical changes.

The Relationship of Dynamic Foot Posture with Injuries and Other Related Factors in Recreational Long Distance Runners

Foot posture is one of the risk factors that is thought to play a role in the occurrence of running-related injuries. This research aims to see if there is an association between foot posture and running-related injuries in long-distance recreational runners. Methods A cross-sectional research was conducted on 131 recreational long-distance runners (94 men and 42 women). Foot posture was determined by Arch Index values calculated from static and dynamic footprints, then tested whether it was associated with running-related injuries. The results showed that dynamic and static foot posture were not associated with running-related injuries in recreational long-distance runners (OR=0.67(0.21-2.20), 95% CI, p=0.516), (OR=0.87(0.29-2.61), 95% CI, p=0.806). On dynamic examination, low arch and high arch foot postures were not associated with running-related injuries in recreational long distance runners (OR=0.67(0.21-2.19), 95% CI, p=0.508), (OR=0.86(0.07-10.67), 95% CI, p=1.00). Most subjects had low arch foot posture on dynamic (83.8%) and static (82.4%) examination. Running-related injuries were found to be 28.7%, with most injuries in the knee (19.5%), calf (17.9%), and sole (15.6%) areas. The conclusions and suggestions in this research are that dynamic and static foot posture are not associated with running-related injuries in long-distance recreational runners, so further prospective research needs to be done to get a clearer picture of other risk factors that cause running-related injuries.

Gender Variation in Squatting Facet of Talus Bone

Context: Talus is the most important key bone of the tarsals as it carries the weight in static and kinetic position during movement. Squatting facet is present on the superior surface of the neck of the talus. Appearance of squatting facet occur due to postural adaptation like squatting position during extreme dorsiflexion in climbing, prolonged standing, harvesting, performing prayers and high arched foot. Squatting facet can determine the race of an individual, can be utilized by forensic experts and anthropologists while dealing with unidentified bones. Material and Method: This cross sectional observational study was conducted on 150 fully ossified dry adult human left tali (of which 83 were male and 67 were female). Types of squatting facets were observed in the Department of Anatomy of Dhaka Medical College, Dhaka from January, 2018 to December,2018. Results: In male, out of 83 left tali, lateral squatting facet were observed in 24 cases (28.9%), medial squatting facet in 4 cases (4.8%), combined (medial and lateral) squatting facet in 9 cases (10.8%), no squatting facet in 46 cases (55.4%). In female, out of 67 left tali, lateral facet were found in 15 cases (22.4%), medial facet in 2 cases (3.0%), combined facet in 5 cases (7.5%) and no squatting facet in 45 cases (67.2%). Conclusion: In the present study, lateral squatting facets were the commonest in both male and female. Bangladesh Journal of Anatomy July 2021, Vol. 19, No. 1, pp. 13-16

A comparison of kinematic and kinetic characteristics of intrinsic flexor muscles of the foot exercises: Effect on the medial longitudinal arch of the foot

Background Standing toe curl (STC) has an immediate effect on muscle activity, but the kinematics of the exercise and its effect on the medial longitudinal arch of the foot are unknown. Objective The purpose of this study was to examine the differences in kinematic and kinetic changes during toe flexion while performing towel curl (TC) in a standing position and STC. Methods Ten healthy adults with normal feet (18 limbs) participated in this study. Using a three-dimensional motion analysis system, we calculated the toe flexion angle, medial longitudinal arch (MLA) angle, MLA height, MLA length, ankle joint angle, center of foot pressure, and center position of the hip joint during toe flexion using TC and STC exercises. Results The TC exercise resulted in a decrease in the MLA due to the backward shift in the center of pressure and ankle dorsiflexion. On the other hand, STC did not demonstrate any significant difference in the position of the center of pressure or ankle joint angle, allowing the toes to flex while maintaining a standing posture and resulting in an increase in the MLA. Conclusions STC was suggested to be effective in maintaining MLA for weight support.

Ankle-hip joint trade-off in normal gait: Exploring the kinematic influence of the medial longitudinal arch of the foot

BackgroundIn human gait, leg progression into the swing phase involves two primary strategies: ankle plantar flexion and hip flexion. These strategies are believed to exhibit a trade-off relationship; however, it is unclear whether this relationship holds for normal gait and the role of the medial longitudinal arch (MLA) in shaping these strategies. Research questionsDoes a trade-off relationship exist between ankle plantar flexion and hip flexion strategies during normal gait in young healthy adults? Do the kinematics of MLA during gait influence the strategies during leg progression into the swing phase? MethodsData from 36 young healthy adults were analyzed. Gait speed and peak moment, angular impulse, peak power and joint work at ankle plantar flexion and hip flexion were assessed within the context of the normal gait task. The parameters were also assessed using ankle-to-hip joint ratios (ankle/hip indices). Kinematics of MLA, including peak MLA angle, amount of descent, and amount of elevation during gait, were also measured. To exclude the effect of gait speed, partial correlation coefficients were employed to explore the relationship between ankle and hip variables as well as the ratio of ankle/hip indices and MLA kinematics. ResultsA significant negative correlation between ankle plantar flexion work and hip flexion work was detected. Moreover, a positive correlation between the ankle plantar flexion work to hip flexion work ratio and MLA elevation was detected. SignificanceA trade-off relationship between ankle plantar flexion and hip flexion strategies during normal gait in young healthy adults was confirmed, suggesting that these parameters are fundamental to normal gait. Additionally, the MLA elevation during late stance may influence the establishment of ankle plantar flexion and hip flexion strategies. These findings enhance our understanding of gait mechanisms and highlight the role of MLA kinematics in shaping gait strategies.

Effect of plantar fascia stiffness on plantar windlass mechanism and arch: Finite element method and dual fluoroscopic imaging system verification

This study explored the relationship between the foot arch stiffness and windlass mechanism, focusing on the contribution of the posterior transverse arch. Understanding the changing characteristics of foot stiffness is critical for providing a scientific basis for treating foot-related diseases. Based on a healthy male's computed tomography, kinematic, and dynamics data, a foot musculoskeletal finite element model with a dorsiflexion angle of 30°of metatarsophalangeal joint was established. Analyze the changes in stress distribution of the plantar fascia, metatarsophalangeal joint angle, arch height, and length during barefoot walking as the stiffness of the plantar fascia varies from 25 % to 200 %. For validation, the simulated arch parameters were compared with the dual fluorescence imaging system measurements. The width of transverse arch, height, and length of longitudinal arch measured by the dual fluorescence imaging system were 45.14 ± 1.63 mm, 29.29 ± 1.57 mm, and 155.16 ± 2.69 mm, respectively. The results of the simulation were 46.51 mm, 29.96 mm, and 156.71 mm, respectively. With the increase of plantar fascia stiffness, the effect of the windlass mechanism increased, the flexion angle of the metatarsophalangeal joint decreased, the distal stress of plantar fascia decreased gradually, while the proximal and middle stress increased, the transverse arch angle increased, but when the plantar fascia stiffness exceeds 150 %, the transverse arch angle decreases. The increase of plantar fascia stiffness will increase the effect of the windlass mechanism but decrease the flexion angle of the metatarsophalangeal joint. The stiffness of the plantar fascia influences the behavior of the plantar fascia. The plantar fascia stiffness affects the distal tension of the plantar fascia by affecting the flexion of the metatarsophalangeal joint in the plantar windlass mechanism. It affects the stiffness of the transverse arch of the foot together with the ground reaction force acting on the distal metatarsal.

Mathematical modelling for seismic affected zoning of tunnel cavity section under SH wave incidence and shaking table verification

Tunnel portals are particularly vulnerable during seismic events due to the influence of adjacent slope geometry and fractured rock formations. This study evaluates the seismic response of tunnel portals and determines an appropriate fortification range. Ray theory is employed to calculate the displacement field of a single-sided slope subjected to incident SH waves, while the tunnel entrance is modeled as an elastic foundation beam. An analytical expression for hoop strain is derived, accounting for the interaction between the tunnel and the surrounding rock, as well as the attenuation of seismic waves. A parametric analysis is also performed to examine the impact of slope angle, seismic wavelength, frequency, and foundation stiffness on the tunnel response. Shaking table tests are conducted to validate the theoretical results and reveal failure patterns in both the slope and tunnel. The findings show that the spandrel and arch foot exhibit the highest hoop strain responses, identifying these positions as critical points of seismic vulnerability. The seismic-affected zones of the tunnel portal are classified into three distinct regions based on the distribution of peak hoop strain. The recommended fortification range for the tunnel portal extends up to 7.5 times the tunnel span, effectively encompassing the areas of peak strain to mitigate potential damage.

USO DE TERAPIAS MANUAIS NA REABILITAÇÃO DA FASCITE PLANTAR: UMA REVISÃO SISTEMÁTICA.

Fasciitis is an inflammation of the plantar fascia, a structure that helps support the medial arch of the foot and is designed to absorb much of the impact. Plantar fasciitis can result from a number of factors, including excessive stress and overload, which can result in inflammation, stress fractures of the calcaneus, compressive neuropathy of the plantar nerves, and more. The aim of this study is to to elucidate how manual therapies can be effective in the treatment of plantar fasciitis. In its preparation, a literature review was carried out to evaluate the effectiveness or not of manual therapies in the treatment of plantar fasciitis, the databases used were: Pubmed, SciElo and PEDro , in Portuguese and English, in the period from January 2019 to December 2024. Ten studies were included to be analyzed in this systematic review, and it showed that manual therapy provides significant benefits, such as reducing pain and improving the function of patients with plantar fasciitis. In conclusion, this study offers valuable insight into how an integrated approach can benefit patients with plantar fasciitis . The findings reinforce the need for personalized treatments, emphasizing that combining different modalities may be key to successful recovery. However, there have been few scientific articles on these manual techniques, so it is worth highlighting the importance of encouraging further studies.

The Relationship of Arcus Pedis Form with Running Speed in Markentho's Football Running Community at Manahan Stadium

Background: Running speed refers to a person's ability to perform consecutive movements to cover a distance in the shortest possible time. This speed is influenced by the arch of the foot (arcus pedis), which can be classified as low, high, or average, and functions as a shock absorber when the foot contacts the ground. Common deformities in abnormal foot structures include pes cavus and flat feet. Aim: To determine the relationship between the condition of the arcus pedis and running speed in the Anak Buah Markentho running community at Manahan Stadium. Methods: This research was conducted on 25 members of a running community. The normality test was performed using the Shapiro-Wilk test, and the hypothesis was tested using Spearman's correlation. Results: The analysis yielded a significance value of 0.000 (p < 0.05), indicating a significant correlation between the shape of the arcus pedis and running speed. The Spearman correlation coefficient was 0.691, showing a positive and strong correlation. Conclusion: Greater deviations in the arch shape are associated with lower running speed, demonstrating a significant and strong correlation. This suggests a clear relationship between the shape of the arcus pedis and running speed.

ВИЗНАЧЕННЯ СИЛОВОГО НАВАНТАЖЕННЯ НА ВЕРХНЮ ЧАСТИНУ ОРТОПЕДИЧНОГО ТА ПІСЛЯОПЕРАЦІЙНОГО ВЗУТТЯ

The results of determining the force load on the upper part of orthopedic and postoperative shoes, taking into account the bending of the sole, are presented. To determine the force of the load on the top of the postoperative orthopedic shoes, the friction forces between the side surfaces of the shoes and the outer sides of the foot were neglected in the work. Thus, the task was reduced to the compilation of equilibrium equations of a plane system of forces. To determine the unknown forces, it was necessary to compile a system of two equilibrium equations, which will represent the algebraic sums of the projections of all forces on the horizontal and vertical axes, which will be equal to zero. The most common type of deformation acting on shoe parts during manufacturing and operation is stretching and bending. It is the last factor that affects the force load on the upper part of orthopedic and postoperative shoes. Deviation of the human musculoskeletal system from the normal anatomical structure and functioning is one of the serious and widespread ailments of the population. An important factor in reducing the inconvenience caused by this disease is the rational choice of orthopedic shoes. Compliance of orthopedic footwear with the functions that rely on it (supporting the arch of the foot, relieving painful areas, making the limb supportive, increasing the area of ​​foot support) is achieved by a reasoned approach to choosing the design of the product, including in the structure of special, special shape and size details, etc.. Degree compliance of this type of footwear with the real needs of the consumer depends on a complex of factors, and the ability to satisfy them is largely determined by the optimal ratio of indicators of reliability and comfort in the use of upper materials. Textile materials are widely used in the footwear industry for uppers, insoles, insoles, linings, and other parts of various types of footwear. This is caused by their valuable consumer properties, such as low hardness and surface density, pleasant texture, high heat-insulating properties, and a variety of artistic and colorful decoration.

The Effect of Towel Toe Curl Exercise and Tibialis Posterior Strengthening on Dynamic Balance of Flatfoot Patients at SD Negeri 104242 Lubuk Pakam

Background: Improper use of the foot can cause problems when walking and even endanger a person's health. The arch of the foot helps withstand impact pressure and provides stability when standing or walking. Flatfoot is a deformity related to the foot, such as medial longitudinal arch disorders of the foot, valgus deformity of the heel, and forefoot abduction. The exercise methods that can be given to overcome flatfoot are Towel toe curl exercise and tibialis posterior strengthening. Purpose: to improve foot function by strengthening the intrinsic muscles of the foot. While tibialis posterior strengthening exercise is to strengthen the tibialis posterior muscle, which is part of the extrinsic muscle. Research method: This type of research is quantitative with a one group pre-test and post-test design. Data analysis using paired sample t-test. The sample of this study were children at SD Negeri 104242 Lubuk Pakam who suffered from flatfoot with a total of 22 samples. The intervention given was towel toe curl and tibialis posterior strengthening 3 times a week for 4 weeks with a total of 12 actions. Before the dynamic balance intervention, respondents were measured first (pretest) with the Y Balance Test (YBT) and re-measured after the intervention (Posttest). Results and discussion: The results of the paired sample t-test obtained a significant value (p) of 0.000, greater than the alpha value (a) (0.000 <0.05), meaning that there is a significant effect of towel toe curl exercises and tibialis posterior strengthening on improving dynamic balance in flatfoot children. Conclusion: Based on the results of the study, it can be concluded that towel toe curl exercises and tibialis posterior strengthening can be one of the training methods that can be applied to overcome dynamic balance disorders in flatfoot sufferers

ВЗАИМОСВЯЗЬ УТОЛЩЕНИЯ СВОДА СТОПЫ И РАЗВИТИЯ ЦНС У ДЕТЕЙ. (ОБЗОР ЛИТЕРАТУРЫ)

Today, the World Health Organization believes that musculoskeletal disorders in children occupy a leading position. According to statistics provided by Russian orthopedists over the past year, 24.2 - 67.3% of schoolchildren, depending on the region, have longitudinal or transverse flat feet. The second most common disorder in children is developmental disorders in the field of intellectual activity. Motor activity is a natural need for people to move. Intellectual development is understood as a set of various cognitive functions of an individual in society: from thinking, as well as perception, to the imagination and thinking of a person. Therefore, studying the relationship between the musculoskeletal and nervous systems in children is an important task of our time. The purpose of our study was to assess the relationship between thickening of the arch of the foot and the development of the central nervous system in children, through the prism of scientific works of orthopedists, pediatricians, neurologists and psychologists. Our review of the literature proves the importance of studying this problem and the need for a clinical study. To improve diagnostics, it is necessary to create a combined universal assessment system that will allow comparing results and conducting a mathematical analysis of the initial state of the musculoskeletal system and intellectual level in children, as well as to analyze changes in the course of therapy. Also, in our opinion, it is necessary to develop a set of exercises for therapeutic physical training that will not only strengthen muscles, form the arches of the feet, but also simultaneously train the frontal lobes of the brain, which will enhance concentration and develop memory. Therefore, we consider it necessary to expand the range and conduct extensive studies with a large sample size.

Research on the Construction Mechanics and Stability Control Technology of Expressway Tunnel Based on Numerical Analysis

As an effective structural form, connecting arch tunnel has been widely used in practical engineering because of its smooth linear shape, small footprint and good bridge and tunnel connection. With the increase of domestic traffic volume year by year, the width of the even arch tunnel is gradually changed from two-way four lanes to two-way six lanes. I20 I-steel, spacing 0.75∼1 m, anchor length 3∼4 m, ring spacing 0.5∼1 m, the side ring spacing of the middle wall is 0.75 m, the side ring spacing of the side wall is 1 m, and the shotcrete thickness is 0.25∼0.3 m. The excavation span of a two-way six-lane continuous-arch tunnel is considerable, leading to complex stress characteristics, thereby posing risks to construction safety and structural stability. Following the construction of the initial tunnel, disturbance to the surrounding rock occurs, affecting subsequent excavation phases. The initial support requirements for subsequent excavations are more intricate, with increased internal forces compared to the initial tunnel segment. As the rear tunnel progresses, the surrounding rock near the middle wall shifts towards the rear tunnel, reducing internal forces in the concrete and steel arch frame. However, as the rear tunnel distance increases, concrete stress and axial forces on the middle wall side of the initial tunnel begin to rise. Throughout the construction, the steel arch frame’s internal forces and spray concrete stress on the middle wall side’s arch waist and foot are the highest, making them susceptible to disruption from construction on the opposite side, thus constituting critical tunnel components. Numerical simulations effectively capture surrounding rock and structural stress dynamics during large-span arch tunnel construction. Simulation outcomes align closely with field measurements, particularly in three-dimensional simulations, enhancing construction understanding and management.

Research on the failure mechanisms and preventive actions of tunnels under butterfly load in loess regions

The results of surrounding rock pressure measurements from numerous loess tunnels exhibit a butterfly distribution pattern, subsequently referred to as ’butterfly load’. This pattern significantly deviates from the load distribution and magnitude—referred to as ’specification load’—calculated by current Chinese tunnel design specifications. By means of model experimental and numerical simulation, the mechanical behavior, failure cause, failure mechanism and preventive actions of tunnel structure under different load distribution are studied. The experimental results indicate that the ultimate bearing capacity of the tunnel structure under the butterfly load is significantly lower than that under the specification load, with the ultimate bearing capacity decreasing as load unevenness increases. The butterfly load increases the unevenness of the axial force distribution throughout the annular structure and also causes the structure to produce reverse moments in the vault and arch shoulder. Similarly, the morphological characteristics of the cracks show that the butterfly load most significantly influences the tunnel vault and arch shoulder. Under the influence of the butterfly load, the lining structure is prone to developing cracks at the arch shoulder and arch foot positions, with tensile cracks located at the vault position. Aiming at the failure mechanism of tunnel structure under butterfly load, it is suggested to implement advanced small conduit grouting at the tunnel arch to suppress the dislocation of the formation and to lay root piles at the arch foot to improve the bearing capacity of the tunnel bottom. The prevention effect of this technology in different loess regions is sandy loess > general loess > clay loess.

Research on the Evolutionary Law of Fracture Formation in Loose Seams Under High-Intensity Mining with Shallow Depth

The western mining regions of China, known for shallow-buried and high-intensity mining activities, face significant ecological threats due to damage to loose strata and the surface. The evolution of fissures within the loose layer is a critical issue for surface ecological environment protection in coal mining areas. The study employed field measurements, mechanical experiments, numerical simulations, and theoretical analysis, using the ‘triaxial consolidation without drainage’ experiment to assess the physical and mechanical properties of various strata in the loose layer. Additionally, the PFC2D numerical simulation software was employed to construct a numerical model that elucidates the damage mechanisms and reveals the evolution of loose layer fissures and the development of ground cracks. The research findings indicate that during shallow-buried high-intensity mining loose layer fissures undergo a dynamic evolution process characterized by “vertical extension-continuous penetration-lateral expansion”. As the working face advances, these fissures eventually propagate to the surface, forming ground cracks. The strong force chains within the overlying rock (or soil) layers develop in the form of an “inverted catenary arch”. As the arch foot and the middle of the arch overlap, fissures propagate along these strong force chains to the surface, resulting in ground cracks. The study elucidates the surface damage patterns in shallow-buried, high-intensity mining, offering theoretical insights for harmonizing coal mining safety with ecological conservation in fragile regions.

Contribution of the plantar fascia and long plantar ligaments to the stability of the longitudinal arch of the foot

The contribution of the Plantar Fascia (PF) and Long Plantar Ligament (LPL), two ligaments extending from the hindfoot to the forefoot, to arch stability has been studied in the past using in vivo, in vitro, and in silico methodologies. In silico studies were based on one single model obtained from one single subject and did not account for the known inter-subject morphological and biomechanical variations. In the present study, we developed computational dynamic models of nine different legs obtained from nine different individuals to evaluate the role of the LPL and PF in arch support, accounting for biological differences between subjects. These models were validated by comparing the simulation results against experimental results from the corresponding cadaver legs. After validation, we simulated body weight conditions for each model by applying a vertical load to the tibia, starting from zero and increasing linearly to 720 N. Kinematic and dynamic parameters, including the variation of the medial arch angle and of the navicular height, as well as the passive forces developed by the LPL and PF, were used to evaluate the contribution of these ligaments to arch support under body weight. The results indicate that a total collapse of the medial longitudinal arch occurred only when both the LPL and PF were absent, but a stable arch was maintained when either one of these two ligament structures were present. The results varied significantly among the specific models, highlighting the importance of using multiple models to account for inter-subject morphological differences.