Steel Arch Research Articles

Study on Bearing Mechanism and Coupling Mechanism of Steel Arch-concrete Composite Structure of Initial Support System of Large Section Tunnel

Fully utilizing and developing underground space is an important direction of future world development. In order to meet the increasing traffic demand, there are more and more super-large section tunnel projects such as two-way eight-lane tunnel. In the initial support system of NATM, “steel arch + concrete shotcrete” is widely used in engineering as one of the most common forms of support. But at present, in the study of supporting system, most researches are based on mechanical analysis of single steel arch, and few of them consider the spatial combination of multi-arch and the influence of concrete shotcrete. Therefore, in order to grasp the spatial combination effect of multi-arch and the influence of concrete shotcrete layer on the bearing mechanism of initial support system, and to establish the analysis and calculation model of initial support system, this paper carries out numerical tests on the mechanical characteristics of three composite steel arch + concrete shotcrete initial support system, and clarifies the spatial combination effect of multi-arch and the effect of concrete shotcrete on initial support. Based on the bearing capacity of the initial support system, the influence of concrete shotcrete strength, arch spacing and longitudinal connection spacing on the mechanical properties of the initial support system is comprehensively analyzed. The research results can provide theoretical basis for the design and application of related engineering.

A Case Study on the Asymmetric Deformation Characteristics and Mechanical Behavior of Deep-Buried Tunnel in Phyllite

When tunneling through deep-buried layered soft strata, asymmetric deformation of surrounding rock and asymmetric mechanical behavior of supporting structures are often encountered. This paper investigates the anisotropic mechanical properties of deep-buried carbonaceous phyllite and its influence on the asymmetrical mechanical behavior of supporting structures in the Zhegu mountain tunnel in Sichuan Province, China. It is a typical road tunnel that suffered from large asymmetrical deformation and cracking of the secondary lining due to layered strata and high geo-stresses. Firstly, experimental tests were conducted to investigate the influence of bedding angle on the mechanical properties and failure behavior of phyllite. Then, the UDEC numerical software was adopted to study the effects of the lateral pressure coefficient, rock layer inclination angle, bedding spacing and shear stress on the mechanical behavior of supporting structures. Moreover, a field test was conducted to measure the pressure between the surrounding rock and the primary support as well as the internal force of the steel arch and the secondary lining. Based on the field data and numerical simulation results, it can be concluded that the asymmetrical deformations of surrounding rock and the cracking of secondary lining in the Zhegu mountain tunnel were results of the coupling effect of layered soft rock and shearing action along the foliation.

Osseointegrated implant as an auxiliary of orthodontic leveling in case of asymmetric vertical skeletal discrepancy – case report

The aim of this work is to present a case report where an osteointegrated implant was used as skeletal anchorage unit in association with fixed orthodontic appliance in the treatment of an adult patient with vertical asymmetrical skeletal discrepancy. In this case report, the pre-existing osseointegrated implant in the region of element 21 was used as an aid of skeletal anchorage for the leveling of the upper occlusal plane by means of the straight-wire technique, Capelozza standard I slot .022 ", using the sequence of arches of nickel-titanium thermo-activated .014 ", .016", .017 "X.025" and .019X.025 ", followed by the steel arch .019" X.025". The results presented in this report demonstrated the osteointegrated implant as a good option, when used as anchorage resource to help orthodontics, providing better conditions of comfort and esthetics, as well as simplifying the technique.

Research on fuzzy PID control of forearm of tunnel steel arch mounting machine

Taking the smooth transition of angular velocity as the key point, the forearm vibration reduction control system based on fuzzy PID control is studied to reduce the influence of the forearm vibration on the docking operation of steel arch. According to the fuzzy rules, the control system establishes the correspondence between the real-time rotation angle error of the forearm and the control signal to reduce the self-vibration caused by the sudden change of the speed at the end of the rotation. By establishing the AMESim-Simulink joint simulation model of the forearm rotation system, the application effect of the fuzzy PID control system on the forearm vibration reduction control is studied. The simulation and experimental results show that this control system effectively reduces the sudden change of the speed and the influence of the self-vibration of the forearm, and each small-angle posture adjustment time can be controlled within 3s.

Comparative Evaluation of Frictional Resistance of Three Different Types of Passive Self-ligating Ceramic Brackets Using Coated and Uncoated Stainless Steel and Nickel Titanium Arch Wires: An In Vitro Study

Comparative Evaluation of Frictional Resistance of Three Different Types of Passive Self-ligating Ceramic Brackets Using Coated and Uncoated Stainless Steel and Nickel Titanium Arch Wires: An In Vitro Study

Mechanical behaviour analysis and support system field experiment of confined concrete arches

Soft rock control is a big challenge in underground engineering. As for this problem, a high-strength support technique of confined concrete (CC) arches is proposed and studied in this paper. Based on full-scale mechanical test system of arch, research is made on the failure mechanism and mechanical properties of CC arch. Then, a mechanical calculation model of circular section is established for the arches with arbitrary section and unequal rigidity; a calculation formula is deduced for the internal force of the arch; an analysis is made on the influence of different factors on the internal force of the arch; and a calculation formula is got for the bearing capacity of CC arch through the strength criterion of bearing capacity. With numerical calculation and laboratory experiment, the ultimate bearing capacity and internal force distribution is analyzed for CC arches. The research results show that: 1) CC arch is 2.31 times higher in strength than the U-shaped steel arch and has better stability; 2) The key damage position of the arch is the two sides; 3) Theoretical analysis, numerical calculation and laboratory experiment have good consistency in the internal force distribution, bearing capacity, and deformation and failure modes of the arch. All of that verifies the correctness of the theoretical calculation. Based on the above results, a field experiment is carried out in Liangjia Mine. Compared with the U-shaped steel arch support, CC arch support is more effective in surrounding rock deformation control. The research results can provide a basis for the design of CC arch support in underground engineering.

Classification of the technical condition of steel arch supports in dog headings with a long-term service life

A large number of dog headings is made and maintained in Polish underground mines that extract hard coal. These headings are often used for many years. However, a gradual deterioration of the technical condition of the supports occurs over all those years, which may pose a serious threat to the safe use of the heading. Therefore, in order to prevent dangerous situations, it is necessary to conduct an ongoing assessment of the technical condition of mine headings and, based on it, make decisions regarding the need to carry out protective and maintenance works. For this purpose, the classification of the technical conditions of steel arch supports suggested in this article can be used. It allows to assess the support conditions according to homogeneous criteria and is a convenient tool to carry out diagnostics of dog headings throughout the entire period of their use. It also gives the possibility to compare different support designs which are used in similar conditions and to verify the developed technical forecasts, regardless of the methodology used to calculate the support.

Assessment of the risk of loss of stability of the steel arch support of the underground excavations

The stability of underground excavations depends on many natural, mining, technical and technological factors. The conducted research has shown that the data accepted for design are often characterized by considerable variability both in time and in space. In order to take into account the variability of parameters characterizing the conditions of maintaining the excavation stability, the probabilistic structure analysis method was used in which the probability of failure was assumed as the risk measure and the values of parameters accepted for analysis as random variables with normal distribution. The paper presents solutions for assessing the safety of excavations based on probabilistic methods of level II and level III. For practical purposes, classification of the degree of risk of loss of excavation stability was proposed, in which the probability of loss of stability (level II method) and probability of dangerous state (level III method) were assumed as a criterion. The general characteristics of the excavation support behaviour were indicated for individual stages. The whole is supported by practical examples from over 20 exploitation fields in several mines of the Upper Silesian Coal Basin. The proposed method can be used both at the stage of design and use of the excavation.

Geotechnical Monitoring and Analyses on the Stability of Highway Tunnel Constructed in Carbonaceous Slate Stratum

There were several damaging behaviors observed in a highway tunnel under construction, caused by the large deformation of rock mass. For this reason, a laboratory test to analyse the mineral composition was implemented, which aims to figure out the cause of the large deformation when tunneling in carbonaceous slate stratum. The laboratory test shows the reactivity of clay minerals with water is one of the important reasons lead to large deformation. Especially, field test was adopted to evaluate the structural stability and safety, affected by large deformation resulted from carbonaceous slate stratum. Displacement of primary lining, internal force of steel arch, pressure between primary lining with rock mass, internal force of secondary lining and seepage pressure of tunnel bottom were monitored and presented during tunneling. The results demonstrate that the mechanical response and stress state of the tunnel reflect the influence of the large deformation. For primary lining, large and asymmetrical deformation, which may result in the failure of steel arch, shows high risk in safety. Moreover, according to the calculated criterion of bearing capacity, once the secondary lining starts to bear pressure from rock mass, unsafety and minor safety reservation of the secondary lining were obtained in two regions of this structure. The result in this paper can provide valuable guidance for the subsequent construction and the similar engineering projects located in this area.

Experimental and numerical studies of double corrugated steel arch panels

Arch structures made of double corrugated steel sheets, known as K-span, are used as self-supporting building roofs. The cold-rolling method of arch panel production causes the creation of deep-press formed transverse corrugation. The unusual profile shape significantly impedes the use of known design methods. In extreme cases, this might lead to the failure and collapse of K-span structures. This paper presents a method for testing full-size K-span structures using various measuring techniques, and provides a method of numerical analysis of the double corrugated structures. The results of the tests were compared with the results of the numerical analysis to assess the validity of the assumptions made for the calculations. A comparison of the test results and the numerical analyses helped to give practical guidelines for evaluation of the load capacity and stability of double corrugated K-span structures.

Evaluation of Coating Stability, Surface Characteristics and Biocompatibility of Nano Particle Coated Stainless Steel, Nickel-Titanium and Beta-Titanium Orthodontic Arch Wires in Comparison with Uncoated Wires: An In-Vitro Study

Background: Friction plays a major role during tooth movement as it takes up to 60% of the applied force, hence reducing the force available for tooth movement. Coating the surface of orthodontic wires by various techniques is being developed to improve their mechanical and biological properties. Objectives: To evaluate the characteristics of nano particle coated and uncoated stainless steel, nickel-titanium, and beta-titanium wires for (1) coating stability, (2) surface characteristics and (3) biocompatibility after 21 days of exposure to artificial saliva. Methods: Six types of wires were tested for coating stability, surface characteristics before and after exposure to artificial saliva using scanning electron microscope and the artificial saliva was tested for leaching of ions by inductively coupled plasma optical emission spectrometer. Results: Coating thickness was reduced in each group after exposure to artificial saliva which was statistically significant. Significant changes in surface morphology such as delamination and irregularity of the coating was noted. Coated NiTi wires showed lesser leaching of ions when compared with uncoated NiTi wires but the difference was not statistically significant. Conclusions: Coating delamination and irregularities were seen in many areas. The highest concentration of ions leached among all the groups were of iron, followed by silica.

Supporting mechanism and mechanical behavior of a double primary support method for tunnels in broken phyllite under high geo-stress: a case study

Large squeezing deformation has always been a critical concern in the construction of deep-buried tunnels in soft-weak rock masses. This paper describes a case study on the large deformation mechanism and supporting method of the Maoxian tunnel in Sichuan Province, China, which is located in the core area influenced by the 2008 Wenchuan earthquake and suffered severe large deformation in broken phyllite under high geo-stress. Through a survey on the geological features, the deformation mechanism of surrounding rock and the failure characteristics of supporting structures of the Maoxian tunnel in F1 fault zone were studied. It was found that the occurrence of large deformation was due to the combined action of the high geo-stress and poor self-stability of carbonaceous phyllite. In order to control the squeezing deformation, single and double primary support methods were adopted in succession. A comparative field test was conducted to study their supporting mechanism and mechanical behavior in terms of surrounding rock pressure, internal stress of the steel arch, and axial force and bending moment of the secondary lining. The results revealed that the single primary support method cannot ensure the long-term safety of the tunnel, since many cracks in concrete occurred after about 180 days. The double primary support method, however, was able to control the large deformation and rheological effects of broken phyllite under high geo-stress effectively.

Vibration-based dual-criteria approach for damage detection in arch bridges

Vibration characteristics of a structure can be used as an indication of its state of structural health as they vary if the structural health is affected by damage. This is the broad principle used in structural health monitoring for vibration-based damage detection of structures. Although most structures are built to have a long life span, they can incur damage due to many reasons. Early damage detection and appropriate retrofitting will enable the continued safe and efficient functioning of structures. This study develops and applies a dual-criteria method based on vibration characteristics to detect and locate damage in arch bridges. Steel arch bridges are one of the most aesthetically pleasing bridge types, which are reasonably popular in Australia and elsewhere. They exhibit three-dimensional and somewhat complex vibration characteristics that may not be suitable for traditional vibration-based damage detection methods. There have been relatively fewer studies on damage detection in these bridge types, and in particular the arch rib and struts, which are important structural components, have received little attention for damage detection. This study will address this research gap and treat the damage detection in the arch bridge structural components using the dual-criteria method to give unambiguous results. The proposed method is first validated by experimental data obtained from testing of a laboratory arch bridge model. The experimental results are also used to validate the modelling techniques and this is followed by damage detection studies on this bridge model as well as on a full-scale long-span arch bridge. Results demonstrate that the proposed dual-criteria method based on the two damage indices can detect and locate damage in the arch rib and vertical columns of deck-type arch bridges with considerable accuracy under a range of damage scenarios using only a few of the early modes of vibration.

Load Capacity of steel arches with shotcrete coating

The shotcrete technology (application of a concrete layer) is widely used in coal mines. The applied layer of shotcrete to the underground workings support, changes the load capacity of the entire supporting system (and its elements). The coating of shotcrete is several times cheaper, faster and safer compared to the traditional reconstruction of the roadways - replacement of the supports. Appropriate selection of shotcrete parameters will allow applying shotcrete to places previously dedicated for reconstruction, and thus reduce the financial resources consumed in the mines for the reconstruction of underground workings. The article presents a method of testing steel arch supports covered with shotcrete, a station for weighting support section and a test plan.

“Wireline + Wireless” Networking Remote Monitoring Technology for Analysing the Unloading Deformation Characteristics of the Fractured Surrounding Rock Mass Induced by Underground Excavation

Collapse or large deformation of fractured surrounding rock mass occurs frequently in underground tunnelling and results in many casualties and extensive property damage. This paper proposed a new type of remote telemetry system for monitoring the mechanical responses of underground tunnels during unloading. This system adopted both wired and wireless networking schemes, including a signal collection and transmission subsystem, a management analysis subsystem, and a remote receiving subsystem, in the tunnels. The application of this new approach in a subway tunnel indicated that the complete unloading performance of a surrounding rock mass can be captured in real time and high frequency using this method, recording the deformation of the surrounding rock, the stress in the bolts, and the stress in the shotcrete between the surrounding rock and steel arch. The in situ experimental study also found that deformation of the fractured surrounding rock mass in the Dashizi Tunnel showed a step‐like fluctuating growth pattern. Additionally, the mechanical response of the surrounding rock mass during unloading tended to stabilize when the opening face was approximately 35 m away from the monitoring section, providing new ways to optimize the excavation process and support measure.

Application of Constant Resistance and Large Deformation Anchor Cable in Soft Rock Highway Tunnel

Muzhailing Highway Extra‐long Tunnel in Lanzhou, Gansu Province, China, belongs to the soft rock tunnel in the extremely high geostress area. During the construction process, large deformation of the soft rock occurred frequently. Taking the no. 2 inclined shaft of Muzhailing tunnel as the research object, an NPR (negative Poisson’s ratio) constant resistance and large deformation anchor cable support system based on high prestress force, constant resistance, and releasing surrounding rock pressure was proposed. The characteristics of the surrounding rock under the steel arch support and NPR anchor cable support were compared and analyzed by using 3DEC software. A series of field tests were conducted in the no. 2 inclined shaft, and the rock strength, displacement of the surrounding rock, deep displacement of the surrounding rock, internal force of steel arch, and axial force of anchor cable were measured to study the application effect of the NPR anchor cable support system in tunnel engineering. Moreover, the 3DEC numerical simulation results were compared with the field test results. The research results show that the application of NPR constant resistance and large deformation anchor cable support system in tunnel engineering has achieved good results, and it plays a significant role in controlling the large deformation of the tunnel surrounding rock.

The resistance to axial dislodgement of nickel titanium compression arch wire hooks – an in vitro study

Abstract Objective To evaluate the level of force required to axially dislodge nickel titanium compression hooks (Trillium Compression HookTM, Hespeler Orthodontics) placed on orthodontic arch wires in vitro. Materials and methods Nickel titanium compression hooks were placed on arch wires with a specially designed pair of pliers. The resistance to axial dislodgement was tested on a total of 260 hooks placed in a standardised way on round (0.016″, 0.018″, 0.020″), square (0.020 × 0.020″) and rectangular (0.016 × 0.022″, 0.019 × 0.025″, 0.021 × 0.025″) stainless steel (Rocky Mountain Orthodontics), nickel titanium, or β-titanium (Hespeler Orthodontics) arch wires. The forces required to displace the hooks were recorded using an Instron tensile testing machine. The data were compared with the results reported in similar studies on stainless steel crimpable arch wire hooks. Results The forces required to dislodge the compression hooks varied between 45.0 N and 161.9 N. The hook’s resistance to dislodgement was found to be high in all tested hook/wire combinations. The lowest recorded average dislodging force was found in the 0.020″ nickel titanium group and the highest average force was in the 0.016 × 0.022″ β-titanium group. Conclusion The forces needed to dislodge the tested nickel titanium compression arch wire hooks exceed the force levels previously reported for stainless steel crimpable arch wire hooks.

Nonlinear analyses of steel beams and arches using virtual unit moments and effective rigidity

This study examined geometric and physical nonlinear analyses of beams and arches specifically from rolled profiles used in mining and underground constructions. These profiles possess the ability to create plastic hinges owing to their robustness. It was assumed that displacements in beams and arches fabricated from these profiles were comparable with the size of the structure. It also considered changes in the shape of a rod cross-section and the nonlinearities of the structure. The analyses were based on virtual unit moments, effective flexural rigidity of used open sections, and a secant method. The use of the approach led to a solution for the after-critical condition in which deformation increased with decreases in loads. The solution was derived for static determinate beams and static indeterminate arches. The results were compared with results obtained in other experimental tests and methods.

Устойчивость по изгибно-крутильной форме стержневых криволинейных элементов стальных арок за пределом упругости

Устойчивость по изгибно-крутильной форме стержневых криволинейных элементов стальных арок за пределом упругости

Устойчивость по изгибно-крутильной форме стержневых криволинейных элементов стальных арок за пределом упругости

Устойчивость по изгибно-крутильной форме стержневых криволинейных элементов стальных арок за пределом упругости