A multi-purpose prototype test system for mechanical behavior of tunnel supporting structure: Development and application

A multi-purpose prototype test system is developed to study the mechanical behavior of tunnel sup-porting structure,including a modular counterforce device,a powerful loading equipment,an advanced intelligent management system and an efficient noncontact deformation measurement system.The functions of the prototype test system are adjustable size and shape of the modular counterforce structure,sufficient load reserve and accurate loading,multi-connection linkage intelligent management,and high-precision and continuously positioned noncontact deformation measurement.The modular counterforce structure is currently the largest in the world,with an outer diameter of 20.5 m,an inner diameter of 16.5 m and a height of 6 m.The case application proves that the prototype test system can reproduce the mechanical behavior of the tunnel lining during load-bearing,deformation and failure processes in detail.

Research progress and application of deep in-situ condition preserved coring and testing

With the depletion of shallow resources,the exploration of deep earth resources has become a global strategy.The study of the different patterns in the physical mechanical properties of rocks at different occurrence depths is the basis for exploring deep into the earth,with the core and premise being the acquisition and testing of deep in-situ core specimens.Based on the original idea of deep in-situ condition preserved coring(ICP-Coring)and testing,combined with theoretical modeling,numerical analysis,test platform development,indoor testing and engineering application,the principles and technologies of deep ICP-Coring are developed.This principle and technology consists of five parts:in-situ pressurepreserved coring(IPP-Coring),in-situ substance-preserved coring(ISP-Coring),in-situ temperaturepreserved coring(ITP-Coring),in-situ light-preserved coring(ILP-Coring),and in-situ moisturepreserved coring(IMP-Coring).The theory and technology of temperature and pressure reconstruction at different occurrence depths and in different environments are proposed,and prototype trial production was completed by following the principle of displacement and tests based on the in-situ reconstructed environment.The notable advances are as follows:(1)Deep in-situ coring system:A pressure-preserved controller with an ultimate bearing capacity greater than 140 MPa,highperformance(temperature-resistant,pressure-resistant,and low thermally conductive)temperaturepreserved materials,an active temperature control system,and high-barrier quality-preserved membrane materials were developed;a deep ICP-Coring capacity calibration platform was independently developed,a deep in-situ coring technology system was developed,and the acquisition of deep in-situ cores was realized.(2)In-situ storage displacement system:Following the dual-circuit hydraulic design idea,a single-drive source push-pull composite grabbing mechanism was designed;the design of the overall structure for the deep in-situ displacement storage system and ultrahigh pressure cabin structure was completed,which could realize docking the coring device and core displacement in the in-situ reconstructed environment.(3)Test analysis system:A noncontact acoustic-electric-magnetic test system was developed under the in-situ reconstructed environment,and the errors between the test results and traditional contact test results were mostly less than 10%;a detachable deep in-situ core true triaxial test system was developed,which could perform loading tests for deep in-situ cores.The relevant technological achievements were successfully applied to the exploration and development of deep resources,such as deep mines,deep-sea natural gas hydrates,and deep oil and gas.The research results provide technical and equipment support for the construction of a theoretical system for deep in-situ rock mechanics,the development of deep earth resources and energy,and the scientific exploration of different layers and occurrence depths(deep and ultradeep)of the Earth.

Prototype test study on mechanical characteristics of segmental lining structure of underwater railway shield tunnel

Based on the first underwater railway shield tunnel,the Shiziyang shield tunnel of Guangzhou Zhujiang River,the prototype test was carried out against its segmental lining structure by using"multi-function shield tunnel structure test system". And the mechanical characteristics of segmental lining structure using straight assembling and staggered assembling were studied deeply. The results showed that,the mechanical characteristics of segmental lining structure varied with the water pressures;especially after cracking,the high water pressure played a significant role in slowing down the growing inner force and deformation. It also testified that the failure characteristics varied with straight assembling structure and staggered assembling structure.Shear failure often occurred near longitudinal seam when using straight assembling.

Field test of multi-hop image sensing network prototype on a city-wide scale

Wireless multimedia sensor networks drastically stretch the horizon of traditional monitoring and surveillance systems. Most existing research has utilized Zigbee or WiFi as the communication technology. Both technologies use ultra-high frequencies (primarily 2.4 GHz) and suffer from a relatively short transmission range (i.e., 100 m line-of-sight). The objective of this study is to assess the feasibility and potential of transmitting image information using RF modules with lower frequencies (e.g., 433 MHz) to achieve a larger-scale deployment as in a city scenario. The Arduino platform is used because of its low cost and simplicity. Details of hardware properties are provided in this article, and we investigate optimum configurations for the system. After achieving an initial range test transmission distance of more than 2000 m line-of-sight, the prototype network is installed in a real life city plot for further examination of performance. A range of suitable applications is proposed and suggestions for future research are provided.

Research on in-situ condition preserved coring and testing systems

As shallow resources are increasingly depleted,the mechanics'theory and testing technology of deep insitu rock has become urgent.Traditional coring technologies obtain rock samples without retaining the in-situ environmental conditions,leading to distortion of the measured parameters.Herein,a coring and testing systems retaining in-situ geological conditions is presented:the coring system that obtains in-situ rock samples,and the transfer and testing system that stores and analyzes the rocks under a reconstructed environment.The ICP-Coring system mainly consists of the pressure controller,active insulated core reactor and insulation layer and sealing film.The ultimate bearing strength of 100 MPa for pressurepreservation,temperature control accuracy of 0.97%for temperature-retained are realized.CH_(4)and CO permeability of the optimized sealing film are as low as 3.85 and 0.33 ppm/min.The average tensile elongation of the film is 152.4%and the light transmittance is reduced to 0%.Additionally,the pressure and steady-state temperature accuracy for reconstructing the in-situ environment of transfer and storage system up to 1%and±0.2 is achieved.The error recorded of the noncontact sensor ring made of lowdensity polymer is less than 6%than that of the contact test.The system can provide technical support for the deep in-situ rock mechanics research,improving deep resource acquisition capabilities and further clarifying deep-earth processes.

In-Situ Test on Fatigue Characteristics of Top-Mounted Dividable Pile-Board Subgrade for High-Speed Railway

To simulate the fatigue characteristics of the pile-board structure under long-term dynamic load, using the in-situ dynamic testing system DTS-1, the forced vibration loading was repeated one million times at different cross-sections of the pile-board structure for high-speed railway. The dynamic deformation, permanent deformation and dynamic stress of main reinforcements were measured. The test results show that the dynamic responses of the pile-board structure almost did not vary with the forced vibration times under the simulated trainload. After one million times of forced vibration, the permanent deformations of the midspan section of intermediate span and midspan section of side span were 0.7 mm and 0. 6 mm, respectively, and there was no accumulative plastic deformation at the bearing section of intermediate span.

Effects of temperature and wavelength choice on in-situ dissolution test of Cimetidine tablets

The effects of temperature and wavelength choice on in-situ dissolution test instrument of Cimetidine were studied. Absorbance （A）〈 1.0 is required when using a fiber-optic dissolution test system. The detection wavelength of 2 （218 nm） was replaced by 244 nm to carry out this test. The absorbance of Cimetidine solution at different temperature showed an obvious change. Calibration of Cimetidine solution should be tested at the same temperature （37° C） with the test solution. A suitable wavelength with smaller tangent slope could be chosen for in-situ dissolution test of Cimetidine tablets.

Design and evaluation of prototype readout electronics for nuclide detector in Very Large Area Space Telescope

China plans to develop the next generation dark matter particle explorer satellite,referred to as the Very Large Area Space Telescope(VLAST).As an essential step in this process,the prototype design of detectors and electronics for the VLAST is currently underway.The nuclide detector is a core detector in the VLAST.It mainly measures nuclides’charges and distinguishes high-energy gamma rays and electrons.This paper will discuss the prototype readout electronics for the VLAST’s nuclide detector,which accurately measures the charge signal of the photomultiplier tubes using the VATA160 applicationspecific integrated circuit chip;furthermore,we consider a series of critical problems,including radiation-hardening and environment monitoring.The test results show that the system exhibits stable operation,good performance,and good technical indicators.Furthermore,each electronic channel achieves a dynamic range of 0-12.5 pC,the random noise level exceeds 1.6 fC,and the integral nonlinearity exceeds 0.35%.

Research of in-situ hydraulic test method by using double packer equipment

Double packer equipment for hydraulic test can be used to measure pressure of test zone directly, and it is frequently used to perform many kinds of hydraulic tests and take groundwater sample from borehole. The test method of this equipment mainly includes the test design, implementation, interpretation and synthetic analysis. By adopting the double packer equipment for hydraulic test, the parameter distribution of rock permeability along borehole can be acquired, as well as the connectivity, water conductivity and water bearing capacity of the disclosed structure and the chemical characteristics of the deep groundwater. It is a necessary method for the research and evaluation of the complex hypotonicity terrace site selection under geological conditions. This method is not only suitable for the geological disposal of high level radioactive waste, but also can be used in the site selection of underground facilities such as storage of petroleum and carbon dioxide. Meanwhile, it has a good application prospect in other hydrogeological investigation fields.

Safety Assessment of Ionic Liquid-Based Lithium-Ion Battery Prototypes

In this paper we report the results of combined cycle- and life-aging and abuse tests carried out under severe conditions on Li4Ti5O12/LiFePO4 lithium-ion stacked prototypes using a PYR14 FSI-LiTFSI ionic liquid electrolyte. No relevant degradation phenomena took place within ionic liquid electrolyte during prolonged inactivity period or overcharging. No fire/explosion or venting event as well as no gas development occurred during abuse tests, which led only to modest raise in temperature. Therefore, electrodes based on Li4Ti5O12 and LiFePO4 active materials can be favorably combined with non-volatile and non-flammable pyrrolidinium FSI ionic liquid electrolytes to realize highly safe lithium-ion battery systems.

Development of a Wireless Environmental Data Acquisition Prototype Adopting Agile Practices: An Experience Report

The traditional software development model commonly named “waterfall” is unable to cope with the increasing functionality and complexity of modern embedded systems. In addition, it is unable to support the ability for businesses to quickly respond to new market opportunities due to changing requirements. As a response, the software development community developed the Agile Methodologies (e.g., extreme Programming, Scrum) which were also adopted by the Embedded System community. However, failures and bad experiences in applying Agile Methodologies to the development of embedded systems have not been reported in the literature. Therefore, this paper contributes a detailed account of our first-time experiences adopting an agile approach in the prototype development of a wireless environment data acquisition system in an academic environment. We successfully applied a subset of the extreme Programming (XP) methodology to our software development using the Python programming language, an experience that demonstrated its benefits in shaping the design of the software and also increasing productivity. We used an incremental development approach for the hardware components and adopted a “cumulative testing” approach. For the overall development process management, however, we concluded that the Promise/Commitment-Based Project Management (PB-PM/CBPM) was better suited. We discovered that software and hardware components of embedded systems are best developed in parallel or near-parallel. We learned that software components that pass automated tests may not survive in the tests against the hardware. Throughout this rapid prototyping effort, factors like team size and our availability as graduate students were major obstacles to fully apply the XP methodology.

Design and feasibility analysis of a new completion monitoring technical scheme for natural gas hydrate production tests

As a prerequisite and a guarantee for safe and efficient natural gas hydrates(NGHs)exploitation,it is imperative to effectively determine the mechanical properties of NGHs reservoirs and clarify the law of the change in the mechanical properties with the dissociation of NGHs during NGHs production tests by depressurization.Based on the development of Japan’s two offshore NGHs production tests in vertical wells,this study innovatively proposed a new subsea communication technology-accurate directional connection using a wet-mate connector.This helps to overcome the technical barrier to the communication between the upper and lower completion of offshore wells.Using this new communication technology,this study explored and designed a mechanical monitoring scheme for lower completion(sand screens).This scheme can be used to monitor the tensile stress and radial compressive stress of sand screens caused by NGHs reservoirs in real time,thus promoting the technical development for the rapid assessment and real-time feedback of the in-situ mechanical response of NGHs reservoirs during offshore NGHs production tests by depressurization.

环端面不平整条件下衬砌管片抗剪承载特性研究

在衬砌管片拼装过程中难免出现环端面不平整(或环缝间垫片局部脱空)的情形,进而在顶推力作用下管片容易产生局部开裂破损,严重时甚至危及衬砌结构安全。鉴于此,以衬砌管片抗剪原型试验为基础,在ABAQUS数值分析平台上建立P2型标准块管片的精细化模型,管片上部设置千斤顶靴板,底部设置垫片并使右侧垫片脱空。在靴板上逐级施加均布荷载,以分析局部脱空情况下衬砌管片在逐级顶推力作用下的力学响应,探讨环端面不平整条件下衬砌管片的裂缝发展过程及抗剪承载特性。数值模拟结果表明:顶推力加载至850 kN,管片脱空端竖向位移达到2 mm,管片内弧面上部出现第1道裂缝,内置钢筋仍处于弹性阶段;加载至1120 kN,脱空端竖向位移达到6 mm,内弧面上出现2道新裂缝,同时第1道裂缝进一步扩展形成内外贯穿性裂缝,即管片裂缝发展过程大致为内弧面→上环端面→外弧面,且裂缝附近上层纵向钢筋达到屈服强度;考虑到内外贯穿裂缝给衬砌管片带来较大渗漏水隐患,认为P2型标准块管片的抗剪承载力(即屈服荷载)约为1120 kN。将数值模拟结果与原型试验结果进行对比,二者所得管片裂缝分布与扩展规律大致一致,抗剪承载力基本相符,验证了数值模拟结果的可靠性。研究成果可为盾构隧道的衬砌设计与掘进施工提供参考依据。

复杂受荷下盾构隧道原型结构试验平台的研发与实证

盾构隧道结构在全寿命周期中往往将面临诸多复杂荷载状态,如注浆、偏载、偏转等非对称偏不利工况。为验证结构在这些复杂荷载状态下的适用性,探究结构力学性能,开展足尺原型结构试验研究往往是最为直接而有效的手段。既有原型试验主要关注隧道结构在简单对称荷载条件下的力学性能,鲜有关注复杂非对称荷载状态。为拓展原型试验的适用范围,提出了适用于不同断面盾构隧道结构的原型试验平台和用于模拟复杂荷载状态的试验荷载设计方法。该方法适用于任意加载点布置和液压站分组的试验系统,可对注浆、偏载、偏转等复杂荷载状态下结构响应进行精确模拟。通过类矩形盾构隧道、双圆隧道和圆形隧道的偏载原型结构试验研究,验证了试验平台和试验荷载设计方法的适用性。进一步针对试验关键参数的分析表明,控制目标权重系数的调整能有效满足不同的试验模拟要求;基于试验荷载设计方法优化的迭代算法能有效考虑计算模型或边界支承条件的非线性;环箍钢绞线和千斤顶的组合加载模式能将拟合误差水平降低至千斤顶加载模式的1/5,但需要删去部分加载点使试验荷载合理且适用;对于越复杂的结构和荷载,精确模拟结构状态需要的试验系统独立荷载组数越高,对试验平台的要求也越高。

基于群桩基础改进的变径微型桩承载特征研究

为改善输电杆塔微型桩基础的承载特性、降低用料成本,提出基于微型群桩改进的变径微型桩基础型式。通过高原山区等截面微型群桩原型试验与数值反演模型相互验证,对3种变径微型单桩进行模拟,并与微型群桩承载效果进行对比分析,揭示变径微型桩的承载特征与变形机理。结果表明:微型群桩基础(2×2单桩)由于承台和群桩效应的影响,其抗压和抗拔承载力分别大于和小于对应的单桩承载力总和;双扩径微型桩(扩径部分直径=2×等截面桩身直径)的极限抗拔和抗压承载力约为等截面微型桩的3.8倍和2.7倍,土体变形集中于扩径部位,且变形量较大,表现为多支点摩擦-端承桩特性;于桩顶增设承台可有效改善双扩径单桩的下压及水平承载性能,与未增设承台相比,承载力分别提高了2.1倍和2.2倍。研究表明,通过扩展部分桩径并增设承台使微型单桩性能提升至等截面群桩水平的方法可行,对送变电建设具有工程意义。

子午工程二期流星雷达样机测试及数据对比分析

子午工程二期将在分布于全国的10个观测站点建设流星雷达.为了带动国内空间环境地基观测技术的发展,工程建设项目指挥部布局了流星雷达的国产化专项行动.为了确保建成后的设备满足使用要求,工程总体组织了设备样机测试,包括设备的技术指标测试和数据质量评估.技术指标测试表明其满足要求.在获得数据之后,以EMDR流星雷达数据为参考,对样机的数据进行质量评估.主要对比参数包括有效流星计数、流星数时空分布、扩散系数高度分布、风场随高度的分布和随时间的变化等.本文主要展示了数据质量评估的结果,揭示了流星雷达观测的一些基本特征和规律,为数据准确性的评估提供参考和借鉴.

飞行器机翼变形驱动机构研究

为了优化飞行器气动特性,提升飞行效率,研究用于连续变弯度机翼的多级连杆驱动机构。采用ANSYS流体分析功能研究最大弯曲角度下变弯度机翼的气动特性;采用ANSYS静力学分析功能研究极限载荷条件下驱动机构的结构强度;并通过仿真分析与样机测试对驱动机构的运动情况进行研究。研究结果表明:变形机翼获得升力系数为1.4,所受最大气流动压1 078 Pa,小于下表面屈服气流动压4 916 Pa;驱动机构所受最大应力37.3 MPa,小于结构屈服强度55.2 MPa;机翼弯曲变形角度可达±25°,满足了飞行器对改善飞行特性方面的需要。

In-situ Horizontal Extrusion Test of Herbaceous Root-Soil with Different Root Types

The influence of different types of roots on the soil is complex and still remains unclear.Four in-situ extrusion tests were conducted on two types of root systems,namely fibrous and tap root system,for three plants,Eleusine indica,Potentilla anserine,and Artemisia argyi,according to the classification in Botany,and the thrust-displacement curves and failure patterns of different samples were analysed by comparison to fill the aforementioned gap.Results reveal that the roots can reduce the characteristics of soil brittleness and enhance its capability to resist large deformation,and different root types contribute different effects to the strain-hardening behavior of the root-soil mass.The contribution of the fibrous root system to strength is limited,whilst the tap root system substantially enhances strength and stiffness.Results of failure patterns show that fibrous and tap root systems affect soil solidification and surface cracking reduction.However,the effect of the tap root system depends on the composition of lateral and tap roots:long and rich lateral roots are effective for resisting the creation of cracks,but thick tap roots with few and thin lateral roots may lead to several surface cracks.

基于Arduino的智能物料搬运机器人设计及样机试验

针对当前生产制造中物料分拣搬运任务的自动化需求,设计出的一款智能物料搬运机器人,分别从机械结构设计、硬件设计、程序设计3个方面对机器人进行研究分析。基于Arduino Mega2560芯片的主控制系统,通过二维码扫描模块获取待搬运物料信息,信息通过串口通信传入主控制器后将搬运信息显示在液晶屏上,机器人通过寻迹到达所需物料区域,通过OpenMV识别搬运物料,将所需物料位置发送给主控制器,控制舵机控制板使机械臂完成对应物料的抓取,运送到物料放置区,识别放置位置并进行物料放置。底盘采用4个麦克纳姆轮,通过灰度传感器,实现机器人的自主运动。根据结构设计,搭建智能物料搬运机器人物理样机,用物理样机进行实验室物料搬运试验,验证了物料搬运过程的稳定性和有效性。

子午工程二期GNSS电离层TEC与闪烁监测仪样机测试及数据对比分析

子午工程二期电离层TEC与闪烁接收机布网采用国产设备.经过连续3天的运行测试,本文以同台站同天线的国外对比设备PolaRx5数据为参考,对样机的数据进行质量评估.对于科学研究,数据的连续性和有效性,VTEC、幅度闪烁指数、相位闪烁指数这三项数据的精度是最重要的指标.本文根据科研场景设计了这些方面的数据比较标准,评估样机的数据质量,并对两种设备探测结果特征的原因进行了分析,为数据准确性的评估提供参考和借鉴.