Temporary Structural Support Research Articles

Chemical Synthesis of Human Proteoforms and Application in Biomedicine.

Limited understanding of human proteoforms with complex posttranslational modifications and the underlying mechanisms poses a major obstacle to research on human health and disease. This Outlook discusses opportunities and challenges of de novo chemical protein synthesis in human proteoform studies. Our analysis suggests that to develop a comprehensive, robust, and cost-effective methodology for chemical synthesis of various human proteoforms, new chemistries of the following types need to be developed: (1) easy-to-use peptide ligation chemistries allowing more efficient de novo synthesis of protein structural domains, (2) robust temporary structural support strategies for ligation and folding of challenging targets, and (3) efficient transpeptidative protein domain-domain ligation methods for multidomain proteins. Our analysis also indicates that accurate chemical synthesis of human proteoforms can be applied to the following aspects of biomedical research: (1) dissection and reconstitution of the proteoform interaction networks, (2) structural mechanism elucidation and functional analysis of human proteoform complexes, and (3) development and evaluation of drugs targeting human proteoforms. Overall, we suggest that through integrating chemical protein synthesis with in vivo functional analysis, mechanistic biochemistry, and drug development, synthetic chemistry would play a pivotal role in human proteoform research and facilitate the development of precision diagnostics and therapeutics.

The Potential of Recycling and Reusing Waste Materials in Underground Construction: A Review of Sustainable Practices and Challenges

Underground infrastructure projects pose significant environmental risks due to resource consumption, ground stability issues, and potential ecological damage. This review explores sustainable practices for mitigating these impacts throughout the lifecycle of underground construction projects, focusing on recycling and reusing excavated tunnel materials. This review systematically analyzed a wide array of sustainable practices, including on-site reuse of excavated tunnel material as backfill, grouting, soil conditioning, and concrete production. Off-site reuses explored are road bases, refilling works, value-added materials, like aggregates and construction products, vegetation reclamation, and landscaping. Opportunities to recover and repurpose tunnel components like temporary support structures, known as “false linings”, are also reviewed. Furthermore, the potential for utilizing industrial and construction wastes in underground works are explored, such as for thermal insulation, fire protection, grouting, and tunnel lining. Incorporating green materials and energy-efficient methods in areas like grouting, lighting, and lining are also discussed. Through comprehensive analysis of numerous case studies, this review demonstrates that with optimized planning, treatment techniques, and end-use selection informed by material characterization, sustainable practices can significantly reduce the environmental footprint of underground infrastructure. However, certain approaches require further refinement and standardization, particularly in areas like the consistent assessment of recycled material properties and the development of standardized guidelines for their use in various applications. These practices contribute to broader sustainability goals by reducing resource consumption, minimizing waste generation, and promoting the use of recycled and green materials. Achieving coordinated multi-stakeholder adoption, including collaboration between contractors, suppliers, regulatory bodies, and research institutions, is crucial for maximizing the impact of these practices and accelerating the transition towards a more sustainable underground construction industry.

Mathematical model of dry stack structural elements with geometric imperfections under a cyclic bending moment

Dry stack structural elements are characterized by nonlinear stiffness that arises from geometric imperfections of their components and the absence of any bonding between them. Moreover, such elements dissipate energy under cyclic loading because of their internal structure. The authors considered dry stack structural elements loaded with a bending moment to propose a relatively simple mathematical model of dry stacks composed of only three elements. The model consists of a linear spring, a nonlinear spring, and a spring with hysteresis in series. In this model, the first element describes the idealized properties of a dry stack element, while the second and third elements correspond to the influence of geometric imperfections and the behaviour of dry joints. Furthermore, the authors described a procedure for determining the parameters of the model based on test results. The proposed solution was verified via experimental studies of temporary support structures consisting of a stack of cuboid elements and a hydraulic jack typically used in the process of building rectification. This study showed that the proposed model adequately describes both the nonlinearity and the energy dissipation under a cyclic bending moment.

Mechanical Properties of Super-large and Shallow-buried Loess Tunnel with the Prefabricated Temporary Support

Background: At present, there are few studies on the mechanical properties of tunnels with prefabricated temporary support. Based on the project of the Xichengshan Tunnel on the highway from Zhuanglang to Tianshui, this paper studies the mechanical properties of tunnels with prefabricated temporary support The utility model patent for this article is a temporary steel support device for loess tunnel excavation. The patent number is ZL 2022 2 0141276. 1. Objective: The study aims to show the mechanical properties of a super large section of prefabricated temporary support shallow tunnel. Methods: The mechanical properties of the tunnel surrounding rock, lining, steel arch, anchor, and temporary support during construction were analyzed by combining numerical simulation and theoretical analysis. The maximum and minimum stresses of the tunnel surrounding rock, lining, steel arch, and anchor, and the maximum and minimum displacements of prefabricated temporary support were found through the analysis results. Results: The stress and displacement fields of surrounding rock, lining, steel arch, bolt, and temporary support of loess tunnel were analyzed. Results showed that the maximum principal stress of the surrounding rock is 0.293MPa, and the maximum horizontal displacement is 0.359cm. The maximum horizontal displacement of the lining is 0.413cm, the maximum vertical displacement of the steel arch is 1.538 cm, and the maximum displacement of the temporary support structure is 1.459 cm. The above data verify the safety of the proposed combined temporary support structure. Conclusion: Through the analysis results, the maximum and minimum stresses of the tunnel surrounding rock, lining, steel arch, and anchor, and the maximum and minimum displacements of assembled temporary support are found, which can guide subsequent construction.

Mechanical analysis of eight-legged temporary support structure under wave forces.

This paper presents a mechanical analysis of the foundation of a temporary offshore platform using a temporary embedded eight-leg support structure. The model is simulated using the finite element simulation software MIDAS-3D, with the modified RANS equation and Forchheimer saturated resistance model used to control the fluid. The stress analysis principle of the structure is simplified by the pile group theory. The stability of the eight-legged supporting structure is investigated under different embedding depths, pile diameters, wave periods, and amplitudes of the main piles. The results show that the eight-legged supporting structure can intercept and divert water flow, eliminating the impact of the water flow on the main piles during large waves. Additionally, as the diameter of the structure increases under the same wave conditions, the influence of the base volume and surface curvature gradually increases, deteriorating the stress environment of the main pile and decreasing the supporting effect of the eight-legged support structure. Numerical calculations of the seabed rock foundation of the eight-leg supporting structure show that the shallow pile foundation undergoes significant deformation, while the eight-leg supporting structure is still supported by the dead weight of the main pile.

Determination of the elastoplastic properties of Ti-6Al-4V alloy manufactured by electron beam melting

PurposeThis study aims to evaluate and assess the elastoplastic properties of Ti-6Al-4V alloy manufactured by Arcam Q20 Plus electron beam melting (EBM) machine by a tensile test campaign and micro computerized tomography (microCT) imaging.Design/methodology/approachASTM E8 tensile test specimens are designed and manufactured by EBM at an Arcam Q20 Plus machine. Surface quality is improved by machining to discard the effect of surface roughness. After surface machining, hot isostatic pressing (HIP) post-treatment is applied to half of the specimens to remove unsolicited internal defects. ASTM E8 tensile test campaign is carried out simultaneously with digital image correlation to acquire strain data for each sample. Finally, build direction and HIP post-treatment dependencies of elastoplastic properties are analyzed by F-test and t-test statistical analyses methods.FindingsModulus of elasticity presents isotropic behavior for each build direction according to F-test and t-test analysis. Yield and ultimate strengths vary according to build direction and post-treatment. Stiffness and strength properties are superior to conventional Ti-6Al-4V material; however, ductility turns out to be poor for aerospace structures compared to conventional Ti-6Al-4V alloy. In addition, micro CT images show that support structure leads to dense internal defects and pores at applied surfaces. However, HIP post-treatment diminishes those internal defects and pores thoroughly.Originality/valueAs a novel scientific contribution, this study investigates the effects of three orthogonal build directions on elastoplastic properties, while many studies focus on only two-build directions. Evaluation of Poisson’s ratio is the other originality of this study. Furthermore, another finding through micro CT imaging is that temporary support structures result in intense defects closer to applied surfaces; hence high-stress regions of structures should be avoided to use support structures.

Evaluating the Safety and the Effect of Blast Loading on the Shotcrete together with lattice girder Support of Tunnels

Damage to tunnels caused by explosions may damage the support structure and the stability. This damage is due to either blasting the working face for drilling progress or an explosion inside the tunnel. The present study investigates the dynamic parameters resulting from the blasting pattern on the temporary support structure of the tunnel considered as a lattice girder and shotcrete equivalent cross-section. For this purpose, LS-DYNA finite element software was used to assess the dynamic response of the structure to the vibration of the blasting-induced explosion. The peak particle velocity (PPV) was considered to evaluate the safety of the tunnel under dynamic loads. According to the results of this study, by exceeding the velocity of 0.9 m/s in the elements, some levels of destruction will occur. Regarding the elements of the temporary support structure of the tunnel, it is found that the damage occurs near the face and 2 m from the tunnel.

Mechanical behavior of an FGM-type frozen soil wall: Theory and numerical analysis.

With a laminate model foundation, we have used the complex variable function method to calculate the boundary displacement and stress of a frozen soil wall in a horizontal connecting passage. Using an actual engineering case, the effects of the number of divided layers of a functionally graded material-type frozen soil wall, the position of the freezing pipe and the section shape of the connecting passage on the displacements and tangential stresses of the frozen soil wall are discussed. The results indicate that the frozen soil wall as a temporary support structure exhibits a good supporting effect. With the increase of layers, the material strength of the frozen soil wall weakens, and the displacements and tangential stresses of the inner boundary increase. When the midline of the freezing pipe moves toward the inner boundary, the tensile area in the frozen soil wall begins to shift, and the displacements and tangential stresses of the inner boundary decrease differently. Thedistributions of internal boundary displacements and tangential stresses are significantly affected by the section shape of the frozen soil wall, and the internal boundary displacements and tangential stresses of the frozen soil wall of the small section are more uniform than those of the frozen soil wall of the large section.

Design and Practice of Deep Foundation Pits for Large Storage Ponds in Complex Environments

Storage ponds (storm detention ponds) are an important part of sponge city construction, and the construction process involves deep and large pit excavation in a complex and sensitive environment. Combined with a large storage pond pit engineering design and practice process, in this study, the complex environment of the design of the large storage pond pit method has been explored, using the field measurement data to test the support design of the deformation control effect and to summarize the practice of the key, difficult points of treatment measures. The results show that the procedure adopted in this project is a successful practice for using the pit characteristics, and the special treatment carried out for addressing the difficult points can effectively control the deformation, thus achieving waterproofing and deformation requirements of large-capacity water storage ponds. The design of the support is very effective in controlling the duration and deformation. The cover-cut excavation method, in combination with the support system, is highly effective in deformation control, whereas the open-cut excavation method is more likely to shorten the duration. However, there is an uncertainty in the deformation control during the removal of temporary structures in this method. The deformation characteristics of the pit enclosure and the surrounding ground surface are within the design requirements. The horizontal displacement of the wall and the surrounding settlement are mainly developed during the stage of dismantling the temporary support structure after excavating the first basement level and during the construction of the first and second slabs. The other stages benefit from the strong integrity of the support system, which can efficiently control the deformation. The treatment measures, support types, and component connection methods summarized in this article can provide a reference for the construction of similar underground storage ponds.

Mechanical behaviour of continuous girder bridge with corrugated steel webs constructed by RW

Abstract Rapid construction of ripple web (RW) is a new construction technology that can be applied to the prestressed concrete (PC) box girder bridge with corrugated steel webs (CSWs). In order to analyse the mechanical behaviour in the construction process when the RW method is applied, the main bridge of Zhao-Jun Yellow River Super Large Bridge was adapted as the engineering background, and a three-dimensional simulation finite element model was established. Thereafter, detailed mechanical analyses were carried out for CSWs, top concrete and bottom concrete, lining concrete, temporary support and other structures in the construction process when the RW method was used. The results reveal the excellent quality of the mechanical properties of the structure, thus indicating the structure’s safety and reliability. This study can provide a reference for similar research and have a positive impact on the further promotion of the RW method for application in the continuous girder bridge with CSWs.

Vibration response and failure modes analysis of the temporary support structure under blasting excavation of tunnels

The blasting impact poses a serious threat to the safety of temporary support structures in tunnel blasting construction, such as a temporary middle wall. Thus, this study investigated and explored these problems. First, the dynamic response results of the temporary middle wall after the explosion were studied according to the field monitoring data. Subsequently, the damage characteristics of the temporary middle wall near the blasting source were investigated on field, and the development stages of the failure evolution were summarized. Furthermore, combined with the explicit finite element software LS-DYNA, the fluid–solid coupling algorithm was used to simulate the vibration response and the failure modes of the temporary middle wall under the condition of different charge weight and blasting distances. According to the field investigation, the closest blasting holes away from the temporary middle wall had a much more significant impact on its damage than other holes. The failure reason of the sprayed concrete of the supporting structure is caused by the excess high peak tension or compression stress. The failure process of supporting structure can be divided into four development stages with the reduced distance away from the blasting source: the appearance of the cracks, the cracks interconnect to form large X-shaped cracks, structural bending-shear coupling failure, and instability failure. The displacement values of the steel arch in the temporary middle wall continuously exceed 7 cm, 20 cm, 28 cm, and 34 cm, respectively, corresponding to the above four failure stages. The relation function containing the blasting tensile stress (BTS) parameter is obtained through dimensional analysis, which can be directly used to design and the damage evaluated of temporary support structures subjected to blasting at close range.

Large deformation characteristics and controlling measures of steeply inclined and layered soft rock of tunnels in plate suture zones

To clarify the inducing factors and mechanisms of geological disasters, such as large deformation and tunnel collapse, tunnels with layered and soft rock in the Luang Prabang suture zone were examined in this paper. Based on an investigation and summary of the disaster characteristics of tunnel deformation, the excavation loosening zone and geo-stress conditions were field-tested by using a sonic detector and a hollow inclusion strain gauge to analyse the correlation between the surrounding rock deformation and the extent of the excavation loosening zone and geostress distribution. The results show that, influenced by the Luang Prabang geological suture zone, underground water and the mechanical characteristics and occurrence of the rock mass, the surrounding rock mass deformation presents obvious asymmetric features. A large deformation of the rock mass more easily occurs at the tunnel crown and right spandrel (waist), and the main deformation phenomena are the spalling and cracking of shotcrete, buckling and bending of the steel arch and large horizontal convergent deformation. According to the sonic velocity monitoring of the rock mass, the scope of the excavation loosening zone of the rock mass is approximately 5.5 m to 7 m, which is beyond 60% of the tunnel width. Based on the field geostress test, the tunnels in plate suture zones bear intensively horizontal tectonic action, and the maximum lateral pressure coefficient of three tunnels is more than 1.5 (σ1/σ3). Thus, the horizontal convergence deformation and supporting structure failure of the tunnel are serious. Some controlling measures were adopted to release and control rock mass deformation, such as improving the advance support structure, enhancing the steel arch strength and increasing the allowed deformation of the rock mass. Moreover, asymmetric support design, such as local borehole grouting and temporary horizontal support structures, also be implemented. Additionally, the optimal design of rock bolt installation and grouting reinforcement depth should be given more attention during tunnelling.

On preventing the dripping effect of overhang constraints in topology optimization for additive manufacturing

This article falls within the scope of topology optimization for Additive Manufacturing processes and proposes an alternative strategy to prevent the phenomenon known as the Dripping Effect. The Dripping Effect is when an overhang constraint is imposed on topology optimization processes for Additive Manufacturing and is defined as the formation of oscillatory contour trends within the prescribed threshold angle. Although these drop-like formations constitute local minimizers of the constraint function, they do not provide a printable feature, and, therefore, they neither eliminate the need to form temporary support structures. So far, there has been no general agreement on how to prevent the Dripping Effect, so this work aims to introduce a strategy that effectively prevents it, and that at the same time may be easy to extrapolate to other types of geometric overhang restrictions. This paper provides a study of the origin of the Dripping Effect and gives detailed instructions on how the proposed prevention strategy is applied. In addition, several benchmark examples where the Dripping Effect is prevented are shown.

Additive Manufacturing of Carbon Nanotube Reinforced Bioactive Glass Scaffolds for Bone Tissue Engineering

Abstract Scaffolds play an essential role in bone healing by providing temporary structural support to the native bone tissue and by hosting bone cells. To this end, several biomaterials and manufacturing methods have been proposed. Among the biomaterials, bio-active glasses have attractive properties as a scaffold material for bone repair. Simultaneously, additive manufacturing (AM) techniques have attracted significant attention owing to their capability of fabricating complex and patient-specific scaffolds. Accordingly, borosilicate bio-active glass (BG-B30) has been used to fabricate the scaffolds using an extrusion-based AM devices in this study. Pluronic F-127 was used as an ink carrier that showed suitable shear thinning behavior for fabrication. The pure BG-B30 scaffold had a compressive strength of 23.30 MPa and was reinforced further with functionalized multiwalled carbon nanotube (MWCNT-COOH) to reduce its brittleness and enhance its compressive strength. When compared to the conventional polymer foam replication technique, the combination of MWCNT-COOH reinforcement and AM resulted in an enhancement of the compressive strength by ∼646% (1.05 MPa to 35.84 MPa). Further, structural analysis using microcomputed tomography revealed that the scaffolds fabricated using AM had better control over strut size and pore size in addition to better network connectivity. Finally, in vitro experiments demonstrated its bio-active behavior by the formation of hydroxyapatite, and the cellular studies revealed good cell viability and osteogenesis initiation. These results are promising for the fabrication of patient-specific CNT-reinforced bio-active glass porous scaffolds for bone tissue engineering applications.

Topology optimization of support structure layout in metal-based additive manufacturing accounting for thermal deformations

This paper focusses on topology optimization of support structures for metal-based additive manufacturing. Processes based on powder bed fusion are subjected to deformations during manufacturing due to large thermal stresses. Controlling these deformations by adding temporary support structures is essential in guaranteeing qualitative end products and improving print success rates. This paper first describes an adapted stiffness tensor formulation for lattice type support structures based on a surrogate model. Next, a general inherent strain method is presented to simulate the complex thermal behaviour of the printed part. These ingredients are used in a topology optimization framework that is capable of automatically generating an optimized support structure layout to limit the vertical displacements of each layer of the printed part to a specified maximum value. The proposed framework is applied to a 2D and 3D benchmark problem to demonstrate that the vertical deformations induced during the manufacturing process are successfully reduced.

Study on Key Construction Procedures of CRD Method for Re Shuitang No.3 Tunnel

Controlling the critical construction steps of the CRD method plays an important role in ensuring construction and ensuring construction safety. When using the CRD method for the construction of the Re Shuitang No. 3 tunnel, through the numerical simulation of the initial support structure and the temporary support structure during the tunnel construction process, it is concluded that the left upper step, the upper right step and the temporary support structure are obviously stressed. Construction steps. According to the analysis results, the surrounding rock of the vault should be strengthened in advance, and the second lining structure should be applied after the surrounding rock is stabilized.

Stretchable Mold Interconnect Optimization: Peeling Automation and Carrierless Techniques

The primary bottleneck of the stretchable mold interconnect (SMI) technology is its reliance on carrier boards. These are necessary to handle the meandered circuit during production and to ensure dimensional stability of the flexible circuit board before encapsulation. However, for all the problems it solves, it also introduces a new major problem by requiring a peeling step—which is difficult to automate. This paper aims to present some of the work that went into eliminating this problem, discussing both unsuccessful and functioning methods to tackle this conundrum and some of the experimental work that went into verifying these techniques. First, alterations to the design to simplify peeling are considered, followed by adhesive-based peeling processes and mechanical pin-based systems. Next, masking and structuring of the carrier board adhesive are considered. Finally, two carrierless methods that circumvent the problems are discussed, a two-step process—which cuts temporary support structures after partial encapsulation—and a technique whereby the frame is designed to fail in a controlled manner during the first use of the circuit, creating a carrierless process feasible for high-volume production.

Combined length scale and overhang angle control in minimum compliance topology optimization for additive manufacturing

This paper focuses on topology optimization for additive manufacturing. In order to ensure that the optimized design is immediately manufacturable, it is essential to take into account the appropriate geometric constraints during the optimization. Two important constraints are minimum length scale and maximum overhang angle. A minimum length scale is needed to ensure that the condition on minimal printable feature sizes is satisfied, while an imposed overhang angle eliminates the need for a temporary support structure. This paper first shows that both constraints cannot simultaneously be met by a straightforward coupling of existing methods for length scale and overhang angle control. Next, a new filtering scheme is introduced, based on a specific combination of spatial filters, which allows direct control over these constraints in a minimum compliance topology optimization problem. A 2D benchmark problem and a complex 3D case study are presented to demonstrate that the proposed filtering scheme successfully imposes a target length scale in both the solid and the void phase of the design domain, while simultaneously allowing control over the overhang angle.

Ground-freezing experience on the east side access Northern Boulevard crossing, New York

A brief review is given of ground-freezing technology as a means of providing groundwater cut-off and temporary structural support in weak ground for transportation tunnelling and shaft-sinking operations. Then, detailed coverage of a particular case history is reported in variable soils in Queens, New York, NY, USA. As part of the upgrading of rail access from Long Island into Manhattan, a tunnel was required that necessitated a frozen arch structure under a ‘live’ roadway and rail lines. The installation, development and performance of the frozen zone are described. At two small locations, groundwater continued to flow through the line of the frozen arch, as the heat in the newly arrived groundwater was greater than the capacity of the ground-freezing technique to remove that heat, thereby preventing final ‘closure’ by the frozen soil at those points. The remedial works to overcome these difficulties are described. Some conclusions are drawn concerning the reasons when and why these localised unfrozen ‘windows’ can be anticipated in freeze zones and about the requirements for remedial solutions.

Antibacterial active open-porous hydroxyapatite/lysozyme scaffolds suitable as bone graft and depot for localised drug delivery.

An engineered synthetic scaffold for bone regeneration should provide temporary structural support and a medium for controlled and localised release of bioavailable medical drugs. In this work, a method is proposed to incorporate biologically active agents without impairing agent activity into open-porous resorbable hydroxyapatite scaffolds. Scaffolds are obtained by a one-pot freeze gelation process and loaded with different amounts of lysozyme, a model macromolecular drug with antibacterial activity. The antibacterial activity is tested by submerging hydroxyapatite scaffolds with 0.5 to 2.5 wt.% lysozyme into two different bacteria stock solutions. A complete dieback of M. luteus bacteria when in contact with the scaffolds is observed. Higher lysozyme amount in the scaffold leads to faster dieback. In contact with scaffolds containing 2.5 wt.% lysozyme after 30 min, no viable bacteria can be observed. An amount of 0.5 wt.% lysozyme in the scaffolds is sufficient to kill all bacteria after a contact time of 24 h. For L. innocua, a bacteriostatic effect is observed. The scaffolds have spongiosa-like stability and are suitable bone implant substitutes. As agents are released from the scaffolds by degrees over a time period of at least 9 days, they are particularly attractive as depot for localised drug delivery of bioactive macromolecular drugs.