Shaft Structures Research Articles

Inrushing failure characteristics of deep shaft structures in soft soils based on material point method simulation

In areas with soft soil, inrushing may occur during the construction of deep shaft structures under high water pressures, causing destructive accidents. Most studies on inrushing have used the finite element method. However, it is difficult to achieve a large deformation simulation because of mesh limitations. The material point method is not constrained by the mesh, and the material properties and motion information of the material are stored at the material points. Therefore, it can be used to effectively simulate large soil deformations. In this study, a numerical model for a deep shaft structure in Shanghai was formulated using the material point method to simulate the evolution of inrushing failure. The likelihood of inrushing damage at different excavation depths was analyzed. Soil heave at the bottom of the pit in the absence of inrushing was examined. The structural and environmental factors affecting the inrushing process are discussed. Strategies have been proposed from different perspectives, such as structure, environment, and construction methods, to reduce the damage caused by inrushing, thereby providing a reference for the safer construction of deep shaft structures.

Erectile Dysfunction Pharmacotherapy Utilization after 60Gy in 20 Fractions Volumetric Modulated Arc Therapy to the Prostate

To determine which factors predict for worsening erectile function after highly conformal, modestly hypofractionated radiotherapy to the prostate. All patients who received 60Gy in 20 fractions, volumetric modulated arc therapy to the prostate across 4 centers over 9 years were included in this study. The provincial electronic medical record was interrogated to identify any new prescriptions for erectile dysfunction (ED) medication, any change in prescription of ED medication or any permanent discontinuance of ED medication persisting beyond 6 months post completion of any androgen deprivation therapy. The penile bulb, penile crux and penile shaft structures were retrospectively contoured. A Youden receiver-operator-curve analysis, logistic regression, and neural network based interpretable machine learning analysis were then used to determine dependencies between worsening ED and clinical factors including mean doses to these structures. Two-hundred-twelve patients with median (inter-quartile-range) follow-up of 3.6 (3.2-4.4) years were identified. Median age was 72 (67-76) years. 104 (49%) patients received androgen deprivation therapy. Prior to treatment, 52 (25%) patients were on ED medication: 20 (9%) on sildenafil, 28 (13%) on tadalafil and 4 (8%) on vardenafil. Median PTV volume was 158.9 (129.8-192.1) cc. Median penile bulb, penile crux and penile shaft volumes were 4.7 (3.6-6.2) cc, 6.5 (5.1-8.5) cc and 93.3 (80.6-106.2) cc, respectively. PTV V95 was 99.8 (99.5-99.9)%. Mean doses to penile bulb, penile crux and penile shaft were 2094.8 (1306.2-3036.3) cGy, 2094.8 (1306.2-3036.3) cGy and 444.4 (313.2-650.5), respectively. Fifty-nine (28%) patients had a worsening of ED after treatment: 25 (12%) started a new ED medication, 6 (3%) had a prescription change and 28 (13%) stopped ED medication. On univariate analyses pretreatment use of ED medication predicted for worsening ED: odds ratio (OR) yes vs no: 10.2 (5.0 - 20.8; p<0.001). A trend towards mean dose to penile bulb [OR ≤2343.9 vs >2343.9: 1.7 (0.9-3.2; p = 0.08)] predicting for worsening ED was observed. Mean doses to penile crux [OR <1725.8 vs > 1725.8: 2.6 (1.3-5.2; p = 0.005)] and penile shaft [OR ≤344.9 vs >344.9: 5.2 (2.2-12.2; p<0.001)] predicted for worsening ED. Use of androgen deprivation therapy, and age at time of radiotherapy were not predictive of worsening ED. On multivariate analysis, only mean dose to penile shaft [OR ≤344.9 vs >344.9: 6.3 (1.9-20.3; p = 0.002)] and pretreatment use of ED medication [OR yes vs no: 11.1 (5.3-23.2; p<0.001)] predicted for worsening ED. A neural network analysis suggested that penile shaft mean dose and pre-treatment ED medication use are the most important factors in predicting worsening ED. In this limited analysis, pre-treatment use of ED medication and mean dose to penile shaft predicted for worsening ED after treatment with modestly hypofractionated radiotherapy for prostate cancer.

Permeability evolution and pore characteristics of reactive powder concrete of drilling shaft with initial salt erosion damage

The aim of this study was to investigate the relationship between permeability properties and pore characteristics of reactive powder concrete (RPC) of drilling shaft under the coupling effect of high-salinity underground water pressure and surrounding rock pressure. Stress–seepage coupling tests were performed on the RPC specimens with standard curing and autoclave curing (prepared using the same mix ratio) after composite salt damage erosion. The characteristics of initial absolute permeability and permeability evolution of RPC in the entire process of volume deformation were analyzed accordingly. Then, computed tomography and AVIZO software were used to construct a three-dimensional meso-equivalent pore network model of RPC. The model was used to analyze the spatial pore structure characteristics of both RPC specimen groups. The results showed that during volume deformation and failure, the permeability of RPC exhibited three stages along with the volume strain: obviously decreasing, sharply rising, and tending to be stable. The larger porosity and more seepage channels in the RPC matrix increased its permeability. Additionally, the pore structure obtained by three-dimensional reconstruction simulation showed that the pore throat area of the RPC specimens with standard curing and autoclave curing ranged from 0 to 11.40 mm2 and 0 to 1.35 mm2, respectively. The size distribution range of their pore throat was 1–8 mm and 1–4 mm, respectively. The research results can accelerate the application of RPC in building drilling shaft structures.

Numerical study of the fire-smoke temperature law in the shaft of a high-rise building under the chimney effect in winter

Shaft structures in high-rise buildings may increase fire coverage due to chimney effects. However, few previous studies have considered the motion of the flue gas under the combined effect of the chimney effect and thermal buoyancy. So, we set a continuous gradient differential pressure opening based on the characteristics of the chimney effect in winter. The CFD method is used to simulate 12 operating conditions with different fire source locations and rates of heat release from the ignition source. We compare and analyze the temperature rise, the flue gas rise law and the variation of the thermal pressure difference between the inner and outer shafts for different fire source powers. The results show that, in the case of low-floor fires, the range of temperature appreciation and fluctuation at the local measurement point increases with the fire power and the distribution of temperature appreciation decreases with the height. The relationship between the dimensionless time and the dimensionless height of the flue gas layer is exponential for different fire position conditions. The fire causes the neutral surface to shift, and below the original neutral surface, the higher the position of the fire source, the more pronounced the shift of the neutral surface.

Improving pose estimation accuracy for large hole shaft structure assembly based on super-resolution.

Image resolution is crucial to visual measurement accuracy, but on the one hand, the cost of increasing the resolution of the acquisition device is prohibitive, and on the other hand, the resolution of the image inevitably decreases when photographing objects at a distance, which is particularly common in the assembly of large hole shaft structures for pose measurement. In this study, a deep learning-based method for super-resolution of large hole shaft images is proposed, including a super-resolution dataset for hole shaft images and a new deep learning super-resolution network structure, which is designed to enhance the perception of edge information in images through the core structure and improve efficiency while improving the effect of image super-resolution. A series of experiments have proven that the method is highly accurate and efficient and can be applied to the automatic assembly of large hole shaft structures.

Durability analysis and damage constitutive modeling of fiber-reinforced reactive powder concrete of drilling shaft in porous water-bearing rock stratum

The drilling activities at the mining sites in western China generally involve an extremely high drilling depth and complex formation environment, and the external load borne by the drilling shaft lining is also very high. Hence, in this study, fiber-reinforced reactive powder concrete (FRRPC) is proposed as the construction material to enhance the durability of deep drilling shaft structures. Firstly, the main physical and mechanical properties of FRRPC are examined by an orthogonal test method. Then, range analysis and comprehensive balance method are used to determine the optimal mix ratio of FRRPC as cement: silica fume: quartz sand: quartz powder: water: water reducer = 1: 0.25: 1.1: 0.40: 0.0237: 0.031. Next, taking C70 concrete commonly used in drilling engineering of deep loose layers in central and eastern China as a control, the permeability resistance and sulfate resistance of drilling shaft FRRPC in porous water-bearing rock stratum are investigated. The results show that compared with the C70 control group, the relative permeability and corrosion resistance coefficient of FRRPC are increased by 87.7% and 9.9%, respectively. Besides, the FRRPC specimen exhibits significantly better impermeability and sulfate resistance than the C70 control group. Finally, a damage constitutive model of FRRPC under sulfate attack is deduced based on the sulfate resistance test. Overall, this study provides useful insights to boost the application of FRRPC in drilling shafts in northwest China.

ДО ПИТАННЯ ГРАФІЧНОЇ РЕКОНСТРУКЦІЇ ДЕРЕВ’ЯНИХ ЕЛЕМЕНТІВ ОБОРОННИХ ВАЛІВ ХVІ–ХVІІ СТ.

The remains of defensive structures are an important component of the holistic perception of the historical context of many settlements in Ukraine. Local administrations show interest in creating graphic reconstructions of monuments as one of the easiest means of popularizing the historical heritage of the area. Over the past decades, the technical capabilities of modeling historical defense objects in three-dimensional images have significantly improved, which has actualized the problem not only of creating realistic images in the transmission of the environment, but also of creating reliable models that can serve as an information base for scientific discussions and the basis of shaping the cultural development of the population. On the way to creating graphic reconstructions of defense structures, a number of problems arise related to the need to reconstruct lost elements about which there is insufficient information. The remains of wooden and earthen fortifications, although they are more numerous than those of masonry, are much worse preserved. Insufficient study of this type of fortifications, especially from the period of the 16th - 17th centuries, can lead to the selection of false analogues and the implementation of unreliable reconstructions. The article applies the methodology of studying defense structures based on the signs of belonging to a certain system of organization of defense structures. Differences in the solution of wooden shaft structures before and after the period of the spread of artillery are characterized. Problems of interpretation of information from written sources about the existence of shafts and their accompanying wooden structures in the 16th–17th centuries are highlighted. Examples of references to wooden elements of bastion fortifications in written sources are given. Treatises on fortification of the 16th–17th centuries have been analyzed. on the subject of determining the principles of strengthening shafts with wooden elements that were used for external equipment (stockade, paling, wattle, palisade, stakes, etc.). Results of our investigations can be applied in graphic reconstruction and visualization of defensive structures of the 16th–17th centuries, carried on according to the principles of the bastion and round bastion systems of fortifications.

Quasi-static mechanical behavior of filament wound composite thin-walled tubes: Tension, torsion, and multi-axial loading

In recent years, with the application of filament wound composite (FWC) materials in shaft structures, the mechanical behavior study of this material under related loads is urgently needed. This paper presented the experimental study on the mechanical behavior of filament wound carbon fiber reinforced polymer under uniaxial tensile loading, torsional loading, and multi-axial loading. To alleviate the stress concentration effect caused by clamping, an improved filament wound specimen was designed and produced by reinforcing each end. A new method of analysis from the inside of a winding pattern was used to investigate failure modes and behavior under different loading conditions. To further describe the mechanical behavior, the strength, stiffness, and failure mechanisms were evaluated by the stress analysis and the measurement techniques, such as the extensometer, the strain gauge, and the scanning electron microscope (SEM). The results show that the pipe is nonlinearly progressively damaged until final failure under tensile load. Brittle failure is dominant under pure torsional load. Under tension–torsional load, the pipe is progressively damaged with slight nonlinearity and the final failure strength is much lower than the pure tension or torsion load condition.

Self-Assembling Flexible 3D-MEAs for Cortical Implants

Abstract Flexible Multi Electrode Arrays (MEAs) for neural interfacing reduce the mechanical mismatch between the soft brain tissue and the electrode arrays allowing accurate signal recordings and neural stimulation while reducing inflammatory responses. Many standard manufacturing processes of MEAs are designed for planar structures and the production of three-dimensional structures is challenging. In the present study, shaft structures with one to two circular gold microelectrodes (10 - 20 μm), each on a base polyimide (PI) substrate, were investigated. We describe a fabrication method, with which shafts made from bi-layer PI flip into the third dimension, which is a first step towards spontaneous assembly of electrodes in flexible 3D MEAs for neuroelectronic applications. A lift-up of the shafts was achieved by the contraction of a second PI layer and a steady nitrogen flow during polycondensation. This shrinking PI was structured in pits with a width of 5 - 600 μm. We achieved liftup angles of up to 42 degrees. The shaft structures can be hardened and later be used for neural implantation experiments.

New analytical algorithm for calculating the end leakage magnetic field of a 300Mvar synchronous condenser under no‐load condition

Aiming at the complexity of end structures in the end region of large synchronous machines, it is difficult to obtain an analytical method for the end leakage magnetic field. In order to solve such a problem, a new analytical algorithm (NAA) considering the influence of the rotor end shaft and air gap is proposed. The mirror image of the rotor end current with the core end plane and the rotor shaft cylinder as mirror surfaces is studied. The air-gap effect is considered by the equivalent air-gap current, and the equivalent air-gap current equation of synchronous machines in the polar coordinate system is derived. Then, a 300Mvar synchronous condenser (SC) is proposed for the first time in China as an example; according to the Biot–Savart law and the superposition principle, the end leakage magnetic field of the SC under no-load condition is calculated, and the influence of different shaft structures on the end leakage magnetic field is analysed. Finally, the calculation results are compared with the 3-D finite element method, which verifies the accuracy of the NAA.

Analysis of earth pressure distribution on deep circular shafts in composite geological strata using centrifuge modelling

With the rapid development of urban underground space, the depth of working shaft has been gradually becoming deeper to accommodate the underground construction needs. The existing studies for earth pressure distribution of shafts are mainly focused on sandy soils within 30 m. There is a strong need to investigate the earth pressure distribution on deep shafts (more than 30 m) in complicated soil conditions using centrifuge modelling to fill the knowledge gap and provide experimental basis for design. In this paper, geotechnical centrifuge modelling was used to investigate the earth pressure distribution along deep circular shaft structures (with a depth of 100 m) in composite geological strata. Three centrifuge tests on model shafts in layered ground with different thickness of clay and sand were carried out, respectively. Drainage method was used in the experiment to simulate the unloading effect caused by excavation of soils inside the shaft model. The earth pressure distributions along the shaft lining before and after the excavation were investigated. The results were analysed and compared with other existing earth pressure theories. This research provides valuable insights for earth pressure distribution for design of circular deep shafts (e.g. 100 m) in composite geological strata.

Analysis on the Influence of Shaft and Cross Passage Turn to the Main Line of Ingate under Different Construction Schemes

In the weak stratum, the construction of ingate is a key technical problem at the place where the shaft and cross passage turn to the tunnel. Based on Lanzhou Metro, the corresponding changes to the construction plan of the ingate of the section tunnel were made. Finite element software is used to carry out three-dimensional modeling and design of subway shaft, cross passage, and tunnel structures in connected sections. The influence of the two construction schemes on surface settlement, deformation, and stress of tunnel support structure and stress conversion of ingate are compared, as well as the fitting degree between numerical simulation results and field monitoring data. Finally, the optimal scheme and key points of construction control are determined. The results show that the optimization scheme has obvious advantages in the control of surface settlement and the deformation of shaft and cross passage support. However, the difference between the stress and deformation of the tunnel supporting structure and the original plan is not obvious. Since the project focuses on shaft, cross passage, and tunnel connection section, the changed construction scheme is better.

Reflection on inactive and energetic survey of sandwich synthesized glazed layers

Right now, study the material and geometric vulnerability consequences for the static, free vibration and dynamic conduct of sandwich shaft structures. A higher-request sandwich board hypothesis is considered for the examination. The flexible properties of the sandwich pillar are considered as 1-D non -Gaussian irregular field which causes neighborhood variety in mass and firmness frameworks of the shaft. The discretization of the non-Gaussian irregular fields is performed utilizing the development ideal direct estimation. To play out the numerical investigation, Monte-Carlo reproduction alongside the computationally proficient time-space ghastly component technique is proposed. Numerical outcomes are acquired for various limit conditions just as for various materials in the sandwich face sheet and center. Results got right now the impacts of material and geometric vulnerability in the reaction conduct of a sandwich shaft. The individual impact of center thickness and Poisson's proportion of the center on the static, free vibration and dynamic reaction is measured. It is seen that the vulnerabilities in material and geometric properties alongside stacking and limit conditions impact the static, free vibration and dynamic reaction.

Evaluation Method of Shaft Structure Stability in Coal Mine Raise Boring Engineering

Raise boring method is one of the key technologies for coal mine shaft construction. The typical engineering of raise boring method is two types: large diameter shafts and small diameter gas pipeline shafts. Ensuring the stability of these two types of shaft structures is a key issue that determines the quality of raise boring engineering. In order to solve this problem, a method of evaluating the stability of shaft structure constructed by raise boring method is proposed in this paper. First, for large-diameter shafts, it is clear that the stability of surrounding rock is the key factor. Based on the strength reduction method, the stability coefficient of surrounding rock k0=2.5 is proposed. Secondly, for the small diameter gas pipe shaft, it is clear that the stability of the gas pipe under the pressure of the filling material is the key factor. The functional equations of allowable compressive stress of the pipe material, the initial deviation of the gas pipes and the ultimate pressure are established, and a method with results biased towards safety is proposed for the design and verification of gas pipes.

Three-dimensional analysis of effects of ground loss on static and seismic response of shafts

During the construction and use of underground structures, it is difficult to avoid ground loss. Previous studies suggested a correlation between ground loss and damage of underground structures. But the current studies are mainly focused on the two-dimensional analysis of tunnels. In the two-dimensional analysis, the simulation of ground loss is flawed, and the results cannot be applied to the shaft structures. Based on the Suzhou River deep underground drainage and storage system, this paper establishes a three-dimensional finite element model of the shaft. Voids of different depth, angle and location are set behind the shaft wall, and the effects of ground loss on static and seismic response of the shaft are analysed. It is found that the existence of ground loss leads to a stress concentration which changes the static deformation and internal force of the shaft. And large positive and negative bending moments occur in the circumference direction which may cause damage to the shafts. During the earthquake, the ground loss will increase the bending moments and reduce the axial pressure. But it has no significant effect on the response in the cross sections. This paper indicates that ground loss can change the static and seismic response of the shaft and it is a potential unsafe factor. Ground loss should be avoided as much as possible during shaft construction, and the impact of ground loss should be considered as appropriate in the design.

Hydrodynamic modelling approaches to assess mechanisms affecting the structural performance and maintenance of vortex drops shaft structures

ABSTRACTVortex drop shafts, a key hydraulic structure within modern day deep sewer conveyance systems, must be designed structurally to sustain performance and longevity of operating life under very energetic loading conditions. This has significant cost implications but to date little research has been undertaken to investigate the loading conditions with a view to optimising the shaft designs and thus lowering costs. In this study, several modelling methods were adopted to simulate hydrodynamic conditions within a vortex drop shaft to assess hydrodynamic mechanisms that impact a drop shaft liners structural performance and maintenance. A 1/10 scaled physical hydraulic model of a tangential inlet vortex drop shaft structure is tested and used to validate a three-dimensional multiphase numerical model. Collectively, the study presents methods on identifying hydrodynamic phenomena such as pressures, velocities, erosion and abrasion mechanisms, debris impact locations and blocking mechanisms. The study highlighted that the hydrodynamic forces that threaten structural integrity reside in the vortex generator and a short length of the drop shaft downstream. This is shown through a new model developed by the authors to predict centrifugal forces along the length of the drop. Through these methods, the study proposes that drop shaft liners can be designed more efficiently.

Identification of torsional receptances

Identification of torsional receptances of shaft structures has been a challenge. This paper presents a method for measuring or estimating high-quality torsional receptances using two different methods based on the Receptance Decoupling Technique. In both methods, a T-block needs to be attached to facilitate the generation of torsion, and only the numerical receptance data of the T-block cast in a simple theoretical model and a few measured receptance data of the assembled system are required. Both methods are studied and assessed in numerical simulation, and the more robust method is further validated in experiments. The usage of rotational accelerometer is shown to significantly improve the quality of the estimation when the noise level is high. It is demonstrated that high-quality torsional receptances can be indirectly measured with high repeatability using the proposed method and thus can be used subsequently to identify torsional modal parameters, update finite element models, make structural modifications, or implement active torsional vibration control. Due to ubiquitous use of rotating machines, this novel method has significant applications.

Dynamic characteristics of cracked uncertain hollow-shaft

Abstract Considering the parametric uncertainties, the model of a rotor system with transverse crack is investigated. Polynomial Chaos Expansion is used to describe the uncertainties. The Harmonic Balance method is employed to solve the dynamic equations of cracked uncertain hollow-shaft system. The application of the PCE in hollow shaft structures will be tested and the results can provide practical reference for engineering context. Validation of present method is verified by comparing with Monte Carlo simulations. From the simulation results, the multi-vibration peaks near the first critical speed and the sub-critical speeds are sensitive to the uncertain parameters. When considering the uncertain parameters, the non-linear responses in harmonic components of the rotor system are key indicators for the detection of transverse crack.

FAM83G/Fam83g genetic variants affect canine and murine hair formation.

FAM83G/Fam83g genetic variants have been described in dogs, mice and recently also in humans. They are associated with palmoplantar keratoderma and altered hair or coat phenotype, reported as wooly phenotype in mice. FAM83G/Fam83g is an unexplored effector of temporally and spatially coordinated Wnt and BMP signalling which are key pathways in pre- and postnatal hair follicle morphogenesis and differentiation. The aim of this study was to unravel phenotypic consequences of FAM83G/Fam83g variants on hair coat formation in dogs and mice. Our results show differences in hair types and hair shaft structures in both species. Additionally, mice exhibit deregulated hair cycle progression which timely correlates with defective Wnt signalling (Axin2) and Bmp2/4 expression. These results affirm the involvement of FAM83G in hair morphogenesis, hair follicle differentiation and cycling.

Optimal Analysis of Tunnel Construction Methods through Cross Passage from Subway Shaft

The conversion section of the cross passage and shaft is a priority concern in the stress transformation of a tunnel structure during subway underground excavation. In the construction of Subway Line 5 in Xi'an, China, the main line in the loess layer was constructed through the cross passage from the subway shaft of the Yue Deng Pavilion–San Dian Village Station tunnel section. Numerical simulation and field measurement were adopted to study the construction stability of the cross passage and shaft under two possible construction methods: the “shaft followed by cross passage construction” method and the “cross passage parallel shaft construction” method. The results showed that the surface deformation and plastic zone of the surrounding rock are similar under the two construction methods. However, of the two, the “cross passage parallel shaft construction” method was more advantageous in controlling the structural deformation of the original shaft and the stress distribution of the horsehead structure. The field monitoring data showed that the surface settlements and the deformation of the original shaft structures meet the requirement of control standards under the “cross passage parallel shaft construction” method.