Numerical simulation of frost jacking response of a single pile considering hydro-thermo-mechanical coupling

Permafrost is widely distributed in China and around the world.In permafrost regions,soil frost heave and thawing are severe and frequent,and can destabilize pile foundations.To this end,a finite element model of a single pile in frozen soil is established to investigate the frost heave and frost jacking response to ensure its safety in the Qinghai-Tibet Plateau.Firstly,a hydro-thermal coupling model of a single pile in frozen soil is established based on coupling parameters and initial and boundary conditions.Then the temperature and moisture distributions are analyzed through the established coupling model.A hydro-thermo-mechanical coupling model is developed by importing the ice content and temperature results.Simulation results indicate that the amount of frost heave is greater at locations closer to the ground surface,and the displacement is smaller for frozen soil that is closer to the side of the pile.The results on frost jacking behavior of piles from this study can serve as a reference for the design,construction and maintenance of foundations.

Finite Element Analysis Study of Box Culvert Jacking-Out Construction under Existing Railway Line

To shorten the existing box culvert demolition construction period and ensure the normal operation of the railway, the jacking-out construction method was adopted. The ABAQUS finite element software was used to establish a three-dimensional model of the box culvert and soil body of the relying project, and three excavation thickness (0m, 1 m, 2 m) were used as the main variation parameters for numerical analysis and research, and the change law of the box culvert itself and soil body stress during the culvert jacking out process was obtained. The results show that the jacking force-displacement curves of the three working conditions can be divided into two stages, and the jacking force reaches the maximum value at the moment when the static friction turns into sliding friction at the end of the first stage. The stress distribution at the bottom slab of the box culvert in the jacking process is approximately normal, and the stress decreases with the increase of the roadbed excavation thickness. The increase of the roadbed excavation thickness can reduce the soil pressure on the side of the box culvert and effectively reduce the deformation of the roadbed in the jacking-out process. The deformation of the roadbed during the jacking process can be reduced by increasing the thickness of the roadbed excavation.

Discussion on the Application of Pipe Jacking Construction Technology in Municipal Road Drainage Projects

In the construction of municipal road drainage projects,pipe jacking construction is a relatively common construction method.This construction technology can avoid a large amount of excavation work,improve drainage construction efficiency,avoid large-scale damage to the road surface,and exert small traffic impact.Therefore,it is currently widely used in drainage construction,but judging from the current actual application situation,there are still many problems that require further improvement.This article mainly analyzes the advantages of and current technical problems in pipe jacking construction technology in detail,explores corresponding solutions,and lays a foundation for the optimization of municipal road drainage engineering construction.

基于JACK虚拟仿真的学龄前脑瘫儿童助行器人机优化设计

目的减少学龄前脑瘫儿童助行器的安全隐患,解决患儿在训练过程中的肢体二次损伤问题,提升助行器人机舒适性,对学龄前脑瘫儿童助行器进行优化设计。方法通过JACK虚拟仿真软件的RULA工具,分析得到学龄前脑瘫儿童在使用助行器过程中存在的不合理姿势,并对其进行人机工学与受力分析,提出改进方法并进行设计优化,最后导入JACK虚拟仿真软件进行风险与舒适性验证。结果优化后的学龄前脑瘫儿童助行器的使用受伤风险从4级降低到1级,患儿躯干弯曲力矩、L4/L5脊柱压缩力、剪切力的姿势载荷指数分别降低53%、47%、81%,上身各关节处于舒适角度。结论经过JACK仿真分析及人机优化后的助行器,有效降低了学龄前脑瘫儿童在康复训练中的二次损伤风险,减轻了患儿步行训练中的身体负担,提升了助行器使用的舒适性。

消防员负重训练姿势仿真分析

目的 研究消防员负重状态下不同训练姿势的损伤风险和疲劳状况,降低其身体损伤和职业病的发生。方法 采用调查问卷对某消防救援大队消防员的训练损伤情况进行详细调查;针对引起损伤原因中占比最高的运动疲劳因素,使用Jack软件中的下背部分析、静态强度分析、疲劳度分析、舒适度分析等人因分析工具,对消防员的4种常用射水训练姿势,以及5层楼负重跑、挂钩梯攀爬科目的训练姿势进行仿真分析。结果 调查问卷统计显示,该消防大队消防员损伤的最主要因素是运动疲劳,其引起的损伤占比为69.8%。4种射水姿势均会造成膝、踝关节受伤的风险增加,4种射水姿势的舒适度从高到低依次为肩扛式、站立式、单膝跪地式、卧倒式。对于5层楼负重跑和挂钩梯攀爬的整个动态训练过程,消防员下背部均不会有增加的损伤风险,但踝、膝关节均有增加的损伤风险。结论 消防员负重训练存在某些训练姿势和部位不适、损伤风险增加等现象。研究结果为预防和降低消防员训练损伤、制定合理的训练计划以及有针对性的防护措施,提供科学的参考依据。

基于Jack的挖掘装载机驾驶室人机工程分析与改进设计

为提高挖掘装载机驾驶室的舒适性,采用人体模型建模分析法确定H点位置,并建立挖掘装载机驾驶室人机仿真系统。以人机分析软件Jack为工具,从驾驶员可视性、可达性及舒适性3方面进行挖掘装载机多作业姿势的人机合理性分析,根据仿真结果对中控台界面及控制部件布局进行改进设计,改进方案的分析校核结果表明:驾驶员可视域得到提升,常用控制部件位于驾驶员舒适可达范围内,改进后驾驶员的多个作业姿势舒适性得到提升。通过人机仿真软件对驾驶员多作业姿势进行人机合理性分析,较准确地发现了挖掘装载机驾驶室存在的设计缺陷,为具有复杂人机系统的工程装备驾驶室布局设计研究提供一定参考。

基于Jack的老年电动代步车人机工程设计与优化

目的满足行动不便的老年用户群体复杂的出行需求,提高电动代步车类工具使用过程中的舒适度。方法在传统老年电动代步车的基础上附加辅助站立结构,创新设计出一款坐、立两用的新型电动代步车,并借助Jack仿真软件,对老年用户坐姿驾驶和辅助站立支撑状态下的舒适度、可达域、可视域,以及上车过程中L4/L5下背部的受力情况进行分析,以验证关键人机交互结构、尺寸设计的合理性及舒适性。结论通过验证和调整,对电动代步车的初期设计方案进行改进,优化后的方案为老年电动代步工具的设计提供了参考,可以为满足老年用户复杂的出行需求、提高电动代步车类工具使用过程中的舒适度和安全性提供帮助。

基于人因学及Jack仿真的消防操作台设计

从人因学的角度出发,根据消防救援任务对车载单人消防机器人操作控制平台进行设计,并依托计算机辅助布局方法和双手作业分析,借助yaahp软件等进行操控器位置协助和布局,针对设计后的人机界面进行了Jack仿真分析,通过人因学多项反应时间实验及按键双手协调实验对设计效果进行分析评价,以减少长期作业带来的疲劳,有效提高作业人员操作的精准性。

基于KE/AHP/SAFC的老年代步工具设计研究

目的针对当下老年代步工具缺乏及设计紊乱问题,从老年代步车入手,通过对在造型设计中审美缺失的关注及对产品功能性的需求进行考虑,提出相关的综合性设计。方法通过资料收集法与市场调研确定代步车感性词汇,并分析造型特征要素,结合层次分析法建立造型设计要素评价体系,通过问卷调研得到符合用户感性需求的造型要素,并以此为主体,结合SAFC模型分析造型要素与功能间的关系,进行功能属性的结构化呈现,运用矛盾冲突解决理论进行创新设计。结果以感性需求为基础,进行代步车造型设计并获取合理的功能解决方案。结论构建集成了感性工学、层次分析法、SAFC理论的产品创新设计流程,并运用设计实践及评价表明了此方法具有一定的可行性。

基于JACK软件的人工检验台人因工效评价

为了提升成品检验台作业人员工作的舒适性,以J公司光伏新能源生产线的成品检验台为研究对象,基于工效学理论,运用Jack软件,构建数字人模型,对成品检验操作台进行建模仿真。对于数字人的工作环境进行了舒适度和疲劳度的检验,发现了其中存在的问题,同时提出了相应的改善措施。数据显示,通过调整工作台布局等方式,数字人的工作舒适度得到显著提升。

基于JACK平台的作战仿真研究

针对目前作战仿真Agent无法适应复杂战场环境、动态规划能力不足的问题,找到了一个基于BDI行为模型的多Agent智能开发平台JACK。基于此平台,开发了装甲步兵班阵地进攻作战仿真系统;依托JACK Team平台,设计了作战仿真Agent能力组件的结构、功能类和行为算法,构建了单兵行为模型和班组行为模型;通过表现模块,实现了JACK Team和Unity3D仿真环境数据交互。同过系统仿真数据统计,验证了JACK平台BDI模型的有效性和与开放环境的良好交互性。

基于Jack仿真的助浴产品作业过程人机优化设计

为解决助浴师在长期上门助浴作业时可能导致的肌肉骨骼疾病问题,本文对助浴产品作业过程进行人机分析和设计优化。首先基于HTA法对助浴行为进行分层归纳,再利用Jack软件模拟助浴环境,对助浴任务进行分析,最后基于分析结果进行人机优化设计实践。本文提出可供参考的助浴床尺寸设计标准,为助浴床增加辅助翻身结构。有助于减少助浴师的疾病风险及提高工作效率,为助浴产品行业提供人机设计标准,促进行业的发展和创新。

移位器仿真优化设计

本研究对市面上一款移位器进行了深入的人机仿真分析。首先,将该移位器的三维模型导入Jack软件中,通过对使用者和照护人员的人机交互进行细致的分析。在此过程中,发现了与人机工程学原理不符的问题。基于这些分析结果,对移位器进行了系统性的优化设计。经过优化后的设计方案再次导入Jack软件,进行了进一步的人机仿真分析,以验证优化设计方案的合理性和有效性。研究结果表明,优化设计后的移位器在使用者和照护人员的体验方面展现出更高水平的舒适性和安全性,这显著提升了产品在满足老年用户需求方面的性能表现。这一优化设计的成功案例为移位器的人机工程学改进提供了有益的实践经验。

基于人体工效学的焊接工人作业姿势与疲劳研究

焊接作业中长期使用不良姿势,容易加速作业疲劳,导致工作相关肌肉骨骼疾患。为了探究作业姿势与疲劳的影响机理,首先,基于人体工效学对典型的不良作业姿势进行改善;其次,以一线焊工为实验对象,通过表面肌电实验,测量焊工左右竖脊肌的表面肌电信号,对两种作业姿势作业过程中的肌肉疲劳特征进行研究;最后,根据实验结果,通过Jack对改善前后的作业姿势进行仿真验证。结果表明:作业姿势改善后效果良好,积分肌电值iEMG下降33.28%,均值方根(RMS)下降39.38%,L4/L5脊椎处压力减少69.8%。

Application of ANSYS 3D FEM in Studies of Surface Deformation Caused by Pipe Jacking

By using site observation data and establishing 3D model using ANSYS software, this paper has discussed the strain change of stratum stress during process of jacking-in and the impact of machine head on ground surface under different frontal resistances. Analysis of the two cases shows that soil pressure reaches its maximum point when the soil is right above machine head, and soil stress will gradually decline when machine head passes over it. It also shows that impact brought by pipe-jacking construction on stress change of the surrounding soil is limited. The thesis suggest that road surface should be consolidated and soil condition be improved before construction to prevent loss and disaster caused by road surface deformation, jacking force can be increased so that jacking efficiency can be enhanced when ground stratum is well filled with soil, but the frontal resistance facing machine head should be equal to surrounding soil pressure in order to avoid rise of ground surface.

A study of jacking force for a curved pipejacking

For a pipejacking, the jacking force is critical to balance the resistance force and to move the pipe string forwards. The driving mechanism of a curved pipejacking is more complicated than a straight-line pipejacking, and its jacking force is also more difficult to be determined. The paper theoretically studies the jacking force of a curved pipejacking by considering the static equilibrium of earth pressure, resistance at cutting face, friction at pipe surface, and the driving force behind the pipe string. The derived theoretical formula can be used to estimate the driving forces of a straight-line or a curved pipejacking. Case study was performed by applying the theoretical and empirical formulae. After calibration, the corrected formula is more accurate and more applicable.

Behavior of Surrounding Soil during Construction and Its Countermeasures Using Pipe Jacking Method in Deep Strata

In Japan when urban infrastructures need to be constructed, the difficulty of utilizing the ground or shallow strata will lead to a more frequent use of the deep strata. The common construction methods are open-cut, pipe jacking, and shield methods. In recent years, a new pipe jacking method has been established that can be adapted to 20 m below the ground or more. Using this method, the drivage machine and the jacking pipe continue to move an underground until the completion of the driving. Therefore an over-cutting area (so-called tail-void) must be formed to lower the friction between the ground and the pipe. The tail-void is filled with lubrications. However, because the stress release from the ground continues to advance when the tail-void is formed, hence there are some challenges required to cope with the stability of the surrounding ground. In order to utilize the pipe jacking method in the deeper strata layers, the theory, analysis and installation of tail-void have to be systemized, and such systematic data must be stored. Therefore, the conditions of tail-void in the deep pipe jacking method are discussed using numerical analyses.

基于Jack的反铲式挖掘机驾驶室人机工程仿真分析与设计改进

为改善反铲式挖掘机驾驶环境,提高驾驶员整体舒适度和工作效率,通过对驾驶环境和作业流程分析,确定了驾驶员常见的操作姿态;利用人机工程仿真分析软件Jack对驾驶员的可视域、可达域和舒适度进行仿真分析,基于分析结果对驾驶室外形、屏幕、推杆角度、座椅横板和扶手进行设计改进;对改进设计方案分析后发现:驾驶员观察铲斗和屏幕的视野盲区减小,常用操作部件位于双手舒适可达范围内,下坡姿势的RULA等级下降,舒适度参数Porter和Krist趋向舒适。通过虚拟人机工程仿真技术可准确预判驾驶室存在的人机工程设计缺陷,提高设计合理性,为人-机-环境总体设计提供参考。

Magma chamber growth models in the upper crust: A review of the hydraulic and inertial constraints

Finite volumes of magma moving in confinement, store hydraulic potential energy for the generation,control and transmission of power. The Pascal's principle in a hydraulic jack arrangement is used to model the vertical and lateral growth of sills. The small input piston of the hydraulic jack is equivalent to the feeder dike, the upper large expansible piston equivalent to the magmatic chamber and the inertial force of the magma in the dike is the input force. This arrangement is particularly relevant to the case of sills expanding with blunt tips, for which rapid fracture propagation is inhibited. Hydraulic models concur with experimental data that show that lateral expansion of magma into a sill is promoted when the vertical ascent of magma through a feeder dike reaches the bottom contact with an overlying, flat rigid-layer. At this point, the magma is forced to decelerate, triggering a pressure wave through the conduit caused by the continued ascent of magma further down(fluid-hammer effect). This pressure wave can provide overpressure enough to trigger the initial hydraulic lateral expansion of magma into an incipient sill, and still have enough input inertial force left to continue feeding the hydraulic system. The lateral expansion underneath the strong impeding layer, causes an area increase and thus, further hydraulic amplification of the input inertial force on the sides and roof of the incipient sill, triggering further expansion in a self-reinforcing process. Initially, the lateral pressure increase is larger than that in the roof allowing the sill to expand. However, expansion eventually increases the total integrated force on the roof allowing its uplift into either a laccolith, if the roof preserves continuity, or into a piston bounded by a circular set of fractures. Hydraulic models for shallow magmatic chambers, also suggest that laccolith-like intrusions require the existence of a self-supported chamber roof. In contrast, if the roof of magmatic chambers loses the self-supporting capacity, lopoliths and calderas should be expected for more or less dense magmas, respectively, owing to the growing influence of the density contrast between the host rock and the magma.

地铁车厢扶手人机工程仿真分析及改进设计

目的为满足地铁乘客站姿乘车的便利性与舒适性,结合人机工程仿真分析软件Jack对车厢扶手的设计方案进行分析校核和改进设计。方法依据GB/T7928—2003中A型车主要技术规格和GB13094—2017中客车扶手尺寸要求,在CAD软件中搭建了地铁车厢内装三维模型;根据GB10000—1988,在Jack软件中建立了第5百分位成年女性和第95百分位成年男性人体数字模型;结果对站姿乘客使用扶手时的不同姿势进行快速上肢动作分析和舒适度分析,得到站姿整体舒适度评分结果;通过人机分析结果,对地铁车厢扶手数量布置和高度设置进行设计改进,并再次通过Jack软件对乘客站姿舒适度进行测试。结论结果表明,改进后的设计方案满足乘客的便利性和舒适性要求,为地铁车厢扶手的人机工程设计提供参考,相关的设计参数值可对现有标准形成补充。