Support Structure Parameters Research Articles

Assessing patient transport conditions during ambulance transit.

Emergency ambulances play a vital role in medical rescue and patient transportation, but their transit can impact patient health due to vehicle dynamic forces and vibrations. This study evaluates patient transport conditions on a stretcher subjected to vertical vibration excitation from road unevenness. Using an eight-degree-of-freedom numerical model, we analyze the construction parameters of a medical stretcher's support and vehicle suspension. Actual experimental data from an emergency vehicle were utilized to assess the vibration conditions experienced by both the stretcher and the ambulance floor. The model is adjusted based on measurements, specifically targeting the main vibration modes. The investigation involves determining temporal responses for vertical accelerations and characterizing vibration modal parameters under various transportation conditions. Notably, several system natural frequencies fall within the range of human body frequencies, making them susceptible to mechanical excitation, particularly in the human neck, abdomen, and spine. A sensitivity analysis underscores the influence of medical stretcher support structure parameters on patient comfort. Increasing support stiffness, which alters the stretcher's natural frequency, and damping coefficient reduce vibration propagation between the vehicle and the patient. Additionally, the research predicts the model's dynamic behavior on roads with low-quality pavement, indicating vibrational amplitudes that could potentially be discomforting and unhealthy for individuals. The study illustrates a vibration exposure period on a class E road, revealing that transportation longer than 25 min may cause damage to patient health.

Risk Reduction Measures and Monitoring Analysis of Deep Foundation Pit with Water in a Metro Station in Hefei

The construction of an urban metro will inevitably involve deep excavation. Risk assessment before deep excavation, risk reduction measures, and real-time monitoring during excavation can effectively ensure the safety of deep excavation. Taking the deep excavation pit of Lingbi Road Station of Hefei Rail Transit Line 8 as the research object, this paper first analyses and evaluates the self-risk, groundwater risk, and surrounding environmental risk of the deep excavation pit, and gives the corresponding measures to reduce the risk of the deep excavation pit. Then, the monitoring content of the excavation process is determined according to the environment of the excavation, the hydrogeological conditions, and the type of supporting structure, and the monitoring scheme is designed. Finally, the entire excavation process is monitored in real time. By analyzing the monitoring data of 13 projects, such as horizontal displacement of the wall top, axial support force, groundwater level, etc., it is found that the monitoring values of 13 projects do not exceed the control value. This proves that the composite internal bracing structure of the underground diaphragm wall is suitable for deep foundation pit support in the Hefei area, as the selection of the water-bearing deep foundation pit support structure, the value of the support structure parameters, and the design of the foundation pit dewatering scheme are all reasonable. The study of this paper also serves as a case reference for the support design of water-bearing deep excavation of subway station in Hefei area.

Influence Analysis of Rock Mass Mechanical Properties on Tunnel Rock Stability Based on Sensor Data Integration

This study takes the multisensor monitoring data of tunnel support structure and surrounding rock mechanical properties during TBM construction as the research object, integrates the monitoring data of multisensor through an intelligent optimization algorithm, and explores the self‐consistent fusion characteristics between the multisensor structural mechanical properties and the field monitoring data. At the same time, the support structure parameters and construction progress in the tunnel construction process are dynamically adjusted and scientifically integrated through the information feedback of monitoring data. The research results are as follows: (1) The tunnel excavation rate is different under different rock strengths and surrounding rock levels. The overall performance is that the harder the surrounding rock, the lower the surrounding rock level, and the faster the tunnel excavation rate. The relationship between the FPI parameters of surrounding rock and the deformation of tunnel surrounding rock is closer, and the correlation coefficient reaches 98%. The mechanical properties of the surrounding rock have the greatest influence on its deformation. (2) The rotation speed, thrust, and torque of TBM machinery as well as the surrounding rock workability index and the tunnel surrounding rock deformation maintain a good fitting relationship, with a fitting rate of more than 85%. After the improved PSO‐BP algorithm is used to calculate and fit the four parameters of torque, rotational speed, thrust, and surrounding rock drivable coefficient during TBM mechanical construction, the fitting accuracy is higher than 94%. (3) At the same time, according to the analysis of the fitting results, the fitting effect of TBM mechanical thrust is the best among the four‐parameter algorithm analysis fitting degrees, which is 99.3%. (4) The measured points are evenly distributed near the surrounding rock deformation surface calculated by the improved PSO‐BP algorithm, and the fitting variance is 0.972. With the tunnel excavation, the settlement deformation of surrounding rock first increases rapidly, and then, the settlement deformation enters a slow growth stage and finally reaches a relatively stable state. (5) After the jam occurs, the tunnel is expanded from the telescopic shield or tail shield to the outer side of the shield to reduce the contact area between the shield and the surrounding rock to reduce the extrusion of the surrounding rock pressure on the shield.

Model Test Study on the Influence of Supporting Structure on the Long-Term Stability of Tunnel Surrounding Rock

Objective: To explore the influence of different supporting structures on the long-term stability of tunnel surrounding rock. Methods: establish the mechanical model of tunnel surrounding rock, and explore its influence on the model shape by changing the support structure parameters. Results: different supporting structures will affect the shape of tunnel surrounding rock model, indicating that it has a certain impact on the long-term stability of tunnel surrounding rock. Conclusion: when carrying out tunnel surrounding rock support, four reasonable support parameter design schemes, such as 0.5m structural plane spacing and 75 ° ~90 ° inclination angle, can be selected to ensure the safety and stability of tunnel surrounding rock to the greatest extent.

Analysis on the Influence Degree of Deformation Control Factors of Deep-Buried Roadway’s Fractured Surrounding Rock Using Orthogonal Design

It is a complex issue to select the support structure parameters for a deep-buried roadway with fractured surrounding rock; especially when the support structure parameters need to be adjusted, the influence degree of support structure parameters on roadway deformation needs to be determined. The deformation of deep-buried roadway’s fractured surrounding rock development was investigated using multi-index orthoplan in this paper. According to the coal mine field investigation, support structure’s failure often occurs, and some need to be repaired many times. Through the roadway surrounding rock drilling, it was found that the stress of the surrounding rock was relieved, resulting in the cavity and separation of the stratum layer. The two sidewalls’ development and roof fractures are mainly tangential, and the original rock state appears only beyond 6.3∼8.2 m. The length of bolts, the row distance between bolts, the length of cables, and the row distance of U-shaped steel were selected as control factors in the multi-index orthogonal design, and roadway’s deformation values were taken as the test indexes. According to the orthoplan, nine numerical simulation schemes were designed, and FLAC3D was used for establishment. The range analysis method was used to analyze the test results. The results show that the control factors’ influence order on the total deformation of the roadway is as follows: row spacing between U-shaped steel > bolt length > cable length > row spacing between bolts, the influence order on the deformation of the roadway floor is as follows: row spacing between U-shaped steel > row spacing between bolts > bolt length > cable length, same as the left sidewall and right sidewall, and the influence order on the roadway roof’s deformation is as follows: row spacing between U-shaped steel > bolt length = cable length > row spacing between bolts, which provide a reference for the support design of deep-buried roadways with fractured surrounding rock, especially the adjustment of the supporting structure.

Investigation of support structure parameters and their affects during additive manufacturing of Ti6Al4V alloy via electron beam melting

Electron beam melting technology offers various benefits like the reduced product cycle time, customization, flexibility, high energy density and less material wastage. However, electron beam melting still suffers from redundant usage of support structure material while fabricating overhang structures. The support structures not only consume additional material, but also require additional time for their design and removal. The optimized support structures have to be designed in such a way that they consume minimum material, are easy to remove and are free from defects. The aim of the current study is to study the effect of support design and process parameters on the performance of the support structures (cost and quality) during additive manufacturing of Ti6Al4V alloy via electron beam melting. The results show that the support structures parameters play a significant role in the cost of the applied support and the accuracy of the fabricated object. It was found that with appropriate selection of support design and process parameters, it is possible to reduce the support volume and hence the fabrication cost in metal additive manufacturing (AM). A tooth height of 3 mm, no support offset of 2 mm, and fragmentation separation width of 0.8 mm resulted in lower support volumes without having any effect on the quality of the overhang. This study systematically investigated the support structure design and their outcomes on overhang fabrication. Its conclusions could add value to the researchers working on additive manufacturing of Ti6Al4V alloy by electron beam melting.

In-situ stress measurement at deep position and optimization of roadway support structure parameters in underground mines

In view of the fact that the mining depth is increasing year by year and the ground pressure disaster is becoming more and more serious in a coal mine, the in-situ stress in deep areas was measured by using the stress relief by overcoring method. The confining pressure rate test and the temperature compensation test were carried out in the laboratory. In-situ stress states and its distribution law ware obtained. Appropriate mechanical parameters and support parameters were selected through research on roadway support theory. By adopting numerical simulation software, the primary support and the secondary support of roadway ware numerically simulated and compared, which can offer a scientific, reasonable and economic plan for the secondary support of roadway. After field application, the roadway support effect had been significantly improved.

Study on the Stability of a Transition Section from Soft to Hard Surrounding Rock Based on the Solid‐Fluid Coupling Effect

To study the stability of a transition section of a tunnel from soft to hard surrounding rock under seepage conditions, FLAC3D software was used to numerically simulate the transition section of the Laomushan Tunnel from the Shiqian to Yuping (Dalong) Expressways in Guizhou Province, China, and to explore different working conditions. The characterization of the tunnel seepage field, stress field, and displacement field and the analysis of the force of the primary lining support structure describe the influence of the seepage field on the stress field distribution and displacement field changes. The reliability of the calculation results is verified by comparison with displacement measurements collected during field monitoring. The design values of the primary support structure parameters of the transition section from soft to hard surrounding rock of the Laomushan Tunnel basically met the strength requirements. The research results provide references for the design and construction of similar projects.

CAD-based design and pre-processing tools for additive manufacturing

This paper discusses a set of geometry based computational pre-processing algorithms developed for Powder Bed Fusion Additive Manufacturing (PBFAM) processes. To start with, based on an initial part design, an automatic support structure generation module generates customized CAD-based support structures for a given part build orientation. Various additive manufacturing (AM) parameters and Design for Additive Manufacturing (DFAM) metrics are calculated on the fly for assigning producibility scores at different part build orientations. A set of stand-alone computational geometry-based algorithms with associated graphical user interfaces (GUI) are developed for calculating support structure parameters, as well as for detecting and highlighting DFAM features that are difficult to manufacture. These stand-alone tools provide a quantified output for each of the parameters or features, which are then used downstream during the producibility index (PI) calculation. An algorithm that evaluates ease of removing supports during the post-processing phase, and suggests the optimum number of setups needed to remove support structures is developed. Finally, Producibility Index, which is a weighted optimization metric, brings together the quantified outputs of the DFAM analysis, support structure parameters, accessibility analysis and suggests the best build orientations for the given part geometry. All the algorithms are implemented within the Siemens NX modelling environment utilizing C++ and NX API functions. The developed algorithm and tools have been succesfully demonstrated on two sample parts.

Part Build Orientation Optimization and Neural Network-Based Geometry Compensation for Additive Manufacturing Process

Significant advancements in the field of additive manufacturing (AM) have increased the popularity of AM in mainstream industries. The dimensional accuracy and surface finish of parts manufactured using AM depend on the AM process and the accompanying process parameters. Part build orientation is one of the most critical process parameters, since it has a direct impact on the part quality measurement metrics such as cusp error, manufacturability concerns for geometric features such as thin regions and small fusible openings, and support structure parameters. In conjunction with the build orientation, the cyclic heating and cooling of the material involved in the AM processes lead to nonuniform deformations throughout the part. These factors cumulatively affect the design conformity, surface finish, and the postprocessing requirements of the manufactured parts. In this paper, a two-step part build orientation optimization and thermal compensation methodology is presented to minimize the geometric inaccuracies resulting in the part during the AM process. In the first step, a weighted optimization model is used to determine the optimal build orientation for a part with respect to the aforementioned part quality and manufacturability metrics. In the second step, a novel artificial neural network (ANN)-based geometric compensation methodology is used on the part in its optimal orientation to make appropriate geometric modifications to counteract the thermal effects resulting from the AM process. The effectiveness of this compensation is assessed on an example part using a new point cloud to part conformity metric and shows significant improvements in the manufactured part's geometric accuracy.

Adaptive tower damping control for offshore wind turbines

This paper deals with the problem of wind turbine tower damping control design and implementation in situations where the support structure parameters vary from their nominal design values. Such situations can, in practice, occur for onshore and especially offshore wind turbines and are attributed to aging, turbine installation, scour or marine sand dunes phenomena and biofouling. Practical experience of wind turbine manufacturing industry has shown that such effects are most easily quanti?ed in terms of the ?rst natural frequency of the turbine support structure. The paper brings forward a study regarding the amount to which nominal tower damping controller performance is affected by changes in the turbine natural frequency. Subsequently, an adaptive tower damping control loop is designed using linear parameter-varying control synthesis; the proposed tower damping controller depends on this varying parameter which is assumed throughout the study to be readily available. An investigation of the fatigue load reduction performance in comparison with the original tower damping control approach is given for a generic three-bladed horizontal-axis wind turbine. Copyright a#169; 2016 John Wiley aamp; Sons, Ltd.

Analysis of the Tunnel-Support Interaction Through a Probabilistic Approach

The analysis of the behavior of a tunnel requires the evaluation of numerous parameters, relative to the ground and the support structure and which are generally only known with a certain degree of approximation. The uncertainty of these parameters is reflected on the results of the calculation, that is, on the state of stress in the support structure. In order to be able to manage this uncertainty on the representative ground and support structure parameters in a rational way, it is useful to resort to a probabilistic type analysis, making use of the Monte- Carlo method and to simple analytical methods for an analysis of the tunnel-support structure interaction. A calculation procedure of probabilistic type that is able to establish representative values of the maximum moment and of the associated normal force in the support structure is presented in this study. This procedure can be used to verify the suitability of the support structure to sustain the induced loads

Supporting Numerical Simulation of Roadway Surrounding Rock in Deep High Stress Based on Broken-Expand Deformation

According to large deformation and supporting problem ofroadway surrounding rock under deep high stress caused by broken-expanddeformation, supporting numerical simulation and optimization on a roadway werestudied. Two primary support scheme of medium length anchor with self-drillinganchor and short pre-stressed anchor withself-drilling anchor and three secondary support scheme of 5m, 6mand 7m length cable were proposedbased on roadway engineering characteristics; Calculationparameters of support structureparameters and surrounding rock were determined based on broken-expanddeformation mechanism, and scheme were calculated respectively; Deformation, plasticzone and stable state of surrounding rock under different support were analyzedbased on results individually, and optimal support scheme were opted. Theresults showed that roadway used 5.5~6.0manchor cable as secondary support whose stability factor can be achieved 1.28could meet productive requirement.

Large Extrusion Deflection Control Technology for Tunnel in Active Fault Zone

The Wushaoling tunnel passes the active engineering fault 7(simply called F7 below), where the surrounding rock is broken, mainly composed of fault boulder clay and rubble with very low strength/geostress ratio, resulting in remarkable deflection. Measures have been taken to control the large deflection of the primary support effectively and to ensure safety of the lining structure so that the F7 can be passed as early as possible . Two small-section roundabout drifts for left and right line each, affected less by the high geostress, are excavated in order to continue the construction ahead, to release partial geostress and to conduct experimental study guiding the design &construction of the main tunnels. At the same time, in-situ experiments are carried on against different pattern and parameters of support structure. Based on the above study, the measures are finally determined such as adopting circular multiple-support composite lining, setting deformation joints per segment to absorb the movement of the active fault, adhering the construction principle of “rapid excavation, rapid support, rapid closure and timely lining”, etc. As a result, the large deflection is controlled effectively in subsequent construction and the large-scale active fault rarely encountered domestic and abroad has been passed successively.