Influence of dynamic pressure on deep underground soft rock roadway support and its application

Due to high ground stress and mining disturbance, the deformation and failure of deep soft rock roadway is serious, and invalidation of the anchor net-anchor cable supporting structure occurs. The failure characteristics of roadways revealed with the help of the ground pressure monitoring. Theoretical analysis was adopted to analyze the influence of mining disturbance on stress distribution in surrounding rock,and the change of stress was also calculated. Considering the change of stress in surrounding rock of bottom extraction roadway, the displacement, plastic zone and distribution law of principal stress difference under different support schemes were studied by means of FLAC3D. The supporting scheme of U-shaped steel was proposed for bottom extraction roadway that underwent mining disturbance. We carried out a similarity model test to verify the effect of support in dynamic pressure. Monitoring results demonstrated the change rules of deformation and stress of surrounding rock in different supporting schemes. The supporting scheme of U-shaped steel had an effective control on deformation of surrounding rock. The scheme was successfully applied in underground engineering practice, and achieved good technical and economic benefits.

Algorithm of sky-ground-wave signal separation in CDMA system

To solve the problem of the sky-wave interference in radio positioning system operating in CDMA mode, an algorithm of sky-ground-wave separation is provided. Based on the MLE （maximum likelihood estimate）, and by estimating the amplitude and the phase of the sky-wave signal, the provided algorithm for separating skyground-wave is implemented. The mathematics model used for signal processing is established, and the possible solutions are provided. The structure and signal processing flow implementing the presented algorithm in the receiver are presented. A multi-channels signal searching idea is adopted, some of which process the sky-wave signal, and some of which process the ground-wave signal. Numerical analysis and simulation show that the proposed algorithm has higher accuracy, more rapid processing speed, and simpler implementation for the estimation of the sky-wave signal parameter, and can separate the sky-wave signal and ground-wave signal from the arrival combination signal effectively.

THE SIMULATION ANALYSIS OF A PROPOSED‘HYDRONIC RADIATOR’SYSTEM TOWARDS LOW COST HOUSING OPERATION IN TEMPERATE AND HOT TROPICAL CLIMATES

Fuel poverty is one of the global concerns affecting not only users’financial capacity or affordability for maintaining housing operation but also the occupants’health and wellbeing.Space heating and cooling require a relatively large amount of domestic energy use in housing.Therefore,this study was formed with the aim to propose an innovative approach to utilising free,clean renewable sources of energy applicable to the space heating and cooling of housing in both cold and hot regions.Accordingly,housing test facilities based in Melbourne,Australia,and Kuching,Malaysia,were selected and used for this study that examined the thermal performance of a proposed‘hydronic radiator’(HR)system through simulation and onsite measurements.The geothermal heat capacity of a‘vertical ground heat exchanger’(VGHE)installed in the house in Melbourne was examined previously by the authors and the VGHE measured data was also applied to this HR performance simulation.The water that circulates through the HRs is heated by sunlight and VGHE or cooled by night sky radiation.This study drew conclusions that the sole utilisation of renewable sources through these proposed HR space heating and cooling systems can provide thermally accessible or comfortable indoor living environments in both heating or cooling dominant regions.Thus,fuel poverty issues may be alleviated through HR system application.The HRs can remove a‘sensible’portion of metabolic heat,but they cannot effectively contribute to the‘latent’heat removal.Thus,the future potential use or effect of‘flow-through’HRs,which are integrated into a underfloor air distribution(UFAD)plenum,was also dsicussed in this study.In the test house located in Melbourne,the flow-through HR UFAD system is currently under development.Therefore,the performance will be measured once the system has come into operation for further testing.

Influence of the Electric Field on the Properties of the Bound Magnetopolaron in GaAs Semiconductor Quantum Wells

The influence of the electric field on the properties of the bound magnetopolaron in an infinite-depth GaAs semiconductor quantum well is investigated using the linear-combination operator and the unitary transformation method. The relationships between the polaron＇s ground state energy and the Coulomb bound potential, electric field, magnetic field, and well-width are derived and discussed. Our numerical results show that the absolute value of the polaron＇s ground state energy increases as the electric field and the Coulomb bound potential increase, and decreases as the well-width and the magnetic field strength increase. When the well-width is small,the quantum size effect is significant.

Research on Data Combination for Phased-Array Ground Penetrating Radar

To resolve the data combination of Phased-array Ground Penetrating Radar (PAGPR), we first build a model of PAGPR and a layered model, and then a new data combination algorithm is presented based on it. This method calculates time delay of multi-receivers, basing on the signal of the nearest receiver, then shifts other signals and adds them up, and gets one signal at last. It has been proved that this method can restrain noise, multiple waves, clutter waves and improve the precision of time location. In the end, an example is given to prove the method's efficiency.

Application of Clausius-Clappeyron Relation (1832) and Carnot Principle (1824) to Earth’s Atmosphere Tricellular Circulation

Atmospheric or climate phenomena are usually a combination of elementary events whose scales range from the very small (microscopic) to the infinitely large (synoptic). This means that build reasoning from ground- or space-based observations only, regardless of the physics of elementary processes, inevitably leads to erroneous results. Given the fact that plots of Troposphere Tricellular Circulation are only based on weather mean conditions measured near the ground (i.e.: pressure and winds fields observed at the surface of the earth), we want to improve these representations of the general circulation of the atmosphere, by using both Clausius-Clapeyron Relation and Carnot Principle derived respectively in 1832 and 1824. Indeed, Clausius-Clapeyron relation shows precisely that, unlike the dry water vapor that can be assimilated to the ideal gas at many circumstances, the saturated water vapor has, in an air parcel at the same time cold (temperature below 0.0098°C) and rich in moisture (vapor pressure above 6.11 mb), thermoelastic properties diametrically opposed to those of ideal gas (including dry water vapor). Vertical profiles of temperature and water vapor in the atmosphere provided by ground- or space-based observations lead to the location of a troposphere region in which the ideal gas assumption should be banned: hence appropriate and unique plot of earth’s atmosphere tricellular circulation.

Equivalent Response Estimation of Structural Systems Subjected to Long-Period Ground Motion

Long-period ground motion has become an important consideration because of the increasing number of large and long-period structures.Therefore,a thorough investigation on the formation and characteristics of longperiod ground motion is desirable for engineering applications.In this work,an analytical study is performed to examine the effect of several parameters and the combining mode for equivalent harmonic components on the dynamic response of systems.The results of the work show that the harmonic components in equivalent ground motion are evidently influenced by the intensity rise time,duration,phase and combining mode.Moreover,the long-period ground motions are simplified and simulated by separate harmonic components through proper combination.The findings of the work are believed to be useful in the selection of input ground motion in structural seismic analysis.

Assessment of the thermal effect of large industrial buildings on permafrost foundation soils in Yakutsk

The results of monitoring studies of the ground thermal state beneath the Yakutsk Combined Heat and Power Plant buildings are presented in order to determine their structural stability and the possibility of further troublefree operation of the entire complex of the structures.The main causes for the formation of water-bearing taliks under and adjacent to the buildings are presented,and the factors influencing the existing geocryological situation are discussed.The continuing stable state of the buildings demonstrates the possibility of using two construction principles on permafrost at one site,including preserving permafrost and accommodating permafrost thawing.

Combined back-analysis method of ground stress based on refined geological modeling

A new back-analysis method of ground stress is proposed with comprehensive consideration of influence of topography, geology and nonlinear physical mechanical properties of rock on ground stress. This method based on non-uniform rational B-spline (NURBS) technology provides the means to build a refined three-dimensional finite element model with more accurate meshing under complex terrain and geological conditions. Meanwhile, this method is a back-analysis of ground stress with combination of multivariable linear regression model and neural network (ANN) model. Firstly, the regression model is used to fit approximately boundary loads. Regarding the regressed loads as mean value, some sets of boundary loads with the same interval are constructed according to the principle of orthogonal design, to calculate the corresponding ground stress at the observation positions using finite element method. The results (boundary loads and the corresponding ground stress) are added to the samples for ANN training. And on this basis, an ANN model is established to implement higher precise back-analysis of initial ground stress. A practical application case shows that the relative error between the inversed ground stress and observed value is mostly less than 10 %, which can meet the need of engineering design and construction requirements.

The future and technique challenges of high-speed ground effect vehicle enrolled in maritime transportation

This paper presents a high-speed ground effect vehicle(HS-GEV)used specifically for maritime transportation.Given the limitations of current vessels,including various types of watercraft and high-speed boats,in fulfilling of needs in different maritime transportation scenarios,the HS-GEV emerges as a promising solution to address unmet requirements.To efficiently accomplish maritime transportation missions with quickness and safety,several critical features are emphasized,including short take-off on water,flight maneuverability and flight stability.The key techniques required to achieve these features,as well as recent progress highlights,are introduced.Following and promoting these crucial techniques is also suggested as a future step to improve HS-GEV performance.With its predominant features,the HS-GEV holds immense application value in enhancing a high-speed maritime transportation system that aligns with the evolving needs of the real world.

多冷媒非均质人工冻结壁弹塑性应力分析

【目的】受制冷媒介温度差异以及被冻地层与冻结管距离差异的影响,多冷媒联合双排管冻结壁的非均匀性较为显著,为了合理评价该类冻结壁的安全性,需开展考虑非均质性的多冷媒人工冻结壁弹塑性应力分析。【方法】选取距离1/4管距处的冻结壁作为特征截面,将该截面上的温度分布曲线等效成三段一次函数形式,并将冻结壁视为随温度成线性变化的非均质材料,分别基于4种冻土屈服准则,推导得出多冷媒联合双排管非均质冻结壁弹塑性应力解析表达式。基于该解析表达式,对多冷媒冻结壁的受力特性进行计算,并将该计算结果与均质冻结壁计算得出的结果进行对比。【结果和结论】研究发现:(1)在盐水-二氧化碳联合双排管冻结壁中,径向应力随着相对半径r的增加而上升,环向应力在不同冻结区间(Ⅰ、Ⅱ、Ⅲ)表现出不同的变化趋势。(2)基于均质冻结壁计算理论,弹性极限状态的冻结壁的环向应力最大值出现在冻结壁内侧,弹塑性状态的冻结壁的环向应力最大值出现在弹塑性分界面处,塑性极限状态的冻结壁的环向应力最大值出现在冻结壁最外侧;而基于非均质冻结壁计算理论,冻结壁环向应力最大值始终出现在冻结壁分区界线(r=2)处。(3)在考虑非均质特性后,冻结壁的弹性极限承载力降低1.8%,而塑性极限承载力提高8.1%。在弹塑性状态下,对应相同塑性区相对半径,非均质冻结壁具有更高的承载力,且这种现象随着塑性区相对半径的增大而愈发明显。研究成果对富水地层多冷媒联合冻结帷幕的设计具有重要的参考价值。

水库库区地形测绘与库容曲线复核技术研究

为提高水库库区地形测绘与库容曲线复核的精准度和效率,采用文献分析、实地调查以及经验总结的研究方法,首先分析了水库库区地形测绘与库容曲线复核的主流技术,总结了测算过程中影响精准度的主要因素及问题解决方法;然后根据水利行业当前相关重点任务和科技发展现状,分析了水库库区地形测绘与库容曲线复核需要进一步研究的问题和发展方向;最后在总结全文的基础上,给出了相关建议。研究表明,水库库区地形测绘和库容曲线复核在测算方法和装备上已经取得比较大的进展,但在如何进一步提高测绘和复核精准度、效率、通用性和智能化水平,以及更高质量地融入水旱灾害防御、数字孪生水利建设和现代化水库运行管理矩阵建设等水利重点工作方面,还有许多问题需要研究。

某钨矿露地联采关键地压灾害监测预警研究

某钨矿形成了露地联采的开采局面,面临着井下群采空区与隔离间柱稳定性、露采边坡稳定性、露地相互影响等关键地压灾害问题。设计建设了最先进的66通道微震监测系统、测量机器人与边坡雷达等地压监测预警系统。文章详细介绍了一次典型的岩体失稳垮塌的成功预警案例。上述综合性的地压监测手段将为矿山安全生产提供重要的技术支撑。

基坑免降水开挖的组合式冻结法支护工艺研究

近年来,随着地下水资源保护力度的不断增大,对基坑工程进行免降水开挖的需求愈加紧迫。为解决富水地层基坑工程施工中的免降水问题,提出一种新的基坑支护方法:传统悬挂式止水帷幕与水平冻土止水帷幕相结合的“组合式冻结法”。根据以往市政工程中的冻结法施工经验,总结组合式冻结法的施工流程,提出泄压孔、温度限位孔和局部冻结技术相结合的冻胀控制措施,以及利用冻结管嵌入地连墙的界面区强化措施。通过模型试验对组合式冻结法的可行性进行验证,试验结果表明,组合式冻结法可以有效实现基底的支护,在冻结薄弱环节临时竖井、地连墙附近冻结壁承载能力满足设计要求;观测发现地层冻结对地连墙强度和变形无明显影响。

面向木结构建筑的绿色性能评价指标体系研究

木结构建筑因其卓越的绿色性能备受关注,然而我国现有的评价标准对这种特殊建筑的评价方面不够系统完善。在综合分析木结构建筑研究概况及现有评价体系的基础上,采取扎根理论建立评价指标体系,通过运用德尔菲法对指标进行优化;采用主客观组合赋权法对各个指标在整体模型中的权重赋权,确保指标权重的科学性、合理性。通过运用扎根理论和德尔菲法的深入分析和专家反馈,细化和优化评价指标,形成木结构建筑绿色性能评价指标体系,包括6个一级指标、31个二级指标,并根据权重分析得到了指标体系对木结构建筑发展的启示,提出了针对性的发展建议,为未来木结构建筑评价提供了一套可靠的评价指标体系。

虚实融合旅游空间的人地互动与想象建构——以故宫深圳数字体验展为例

在新冠疫情的影响下,数字时代旅游情境下的新型“人地关系”成为新兴议题。文章借助Python从微博、小红书、抖音APP抓取关于“纹”以载道——故宫腾讯沉浸式数字体验展UGC数据作为研究样本,采用LDA主题挖掘和扎根理论分析,探究虚实融合旅游空间中人地互动过程与机理。研究发现:第一,旅游者对虚实融合旅游空间的感知主要表现在:对地方景观和遗产价值的感知(文化与艺术元素、建筑与景观)、对现实展览空间载体的感知和对科技与数字叙事的感知三个方面;第二,借助VR、AR等数字技术,游客通过人-机-地智能交互、体感交互、多感官互动和价值共创,在倦勤斋等数字叙事空间中获得“现实身体共在”和“远程虚拟在场”的双重沉浸感体验;第三,沉浸式数字体验空间通过多重空间(虚空间、实空间和虚实融合空间)的互动关联与动态响应,在“第三空间”中串联与协商文化想象、具身感知和地方知识,产生情感共鸣与认同,实现地方意义的深度挖掘与价值延伸。文章通过聚焦虚实融合旅游空间中人地互动和地理想象,拓展了虚实空间二元论与旅游地三元空间交互理论,可为沉浸式旅游新场景打造、人地互动体验重塑和文化遗产数字活化提供决策依据。

塑料排水板地基侧向变形的模型试验与仿真分析

为探明不同预压模式下塑料排水板(prefabricated vertical drains,PVD)处理软土地基的侧向变形特性,以指导软土地区相关工程的设计与施工,通过室内大比例模型试验对比分析堆载预压和真空联合堆载预压下PVD地基的侧向变形特性。此外,结合有限元仿真分析,系统研究真空联合堆载预压下堆载速率(LR)、堆载大小(p_(s))和真空压力大小(|p_(v)|)对PVD地基侧向变形的影响规律。研究表明:真空联合堆载预压相较堆载预压可以匹配更快的堆载速率和更大的堆载,且达到最大堆载后的后续固结阶段,PVD地基的向外侧向变形并无明显增长,反观堆载预压工况,地基的最大向外侧向变形仍可增长达10%,局部深度位置侧向变形可增长超30%。真空联合堆载预压下PVD地基的侧向变形轮廓整体随p_(s)与LR的增加及|p_(v)|的减小而向预压区外侧移动,且地基的侧向变形速率及最大向外侧向变形(δ_(om))深度随之增加。此外,堆载施加过程中PVD地基的向外侧向变形呈阶梯型规律增加,其最大值δ_(om)近似随p_(s)增加而线性增大,随LR增加及|p_(v)|减小而非线性增长。同等荷载改变量下,|p_(v)|的改变相较于ps改变对地基侧向变形的影响更为显著。研究结果可为真空联合堆载预压处理软土地基的分析与设计提供参考。

装配式柔性墙体日光温室联合储热系统蓄放热特性

增设多蓄热介质联合主动蓄放热系统是解决装配式柔性墙体日光温室“重保温、轻蓄热”问题的有效方法,但当前对于“土壤-空气-水”多介质联合储热系统蓄放热特性和加温效果尚不明确,针对此问题,该研究以配备“空气源地中热交换-水源后墙循环换热”联合储热系统的装配式柔性墙体日光温室为研究对象,采用现场跟踪测试和能量转移测算,对联合储热系统各自和组合的蓄放热特性进行研究。结果表明,配有联合储热系统的装配式柔性墙体日光温室室内夜间最低空气温度维持在10℃以上,室内外最大温差达26.5℃。0~50 cm的土壤层是该温室主要蓄热介质,晴天土壤层蓄热量最高占总蓄热量的63.5%。地中热交换系统最高占土壤蓄热量的54.4%。水循环系统蓄热量可达424.04 MJ,最高占总蓄热量的45.1%,通过循环蓄热可将储水池内8 m3水的温度提高到35℃。连阴天时,通过引入蓄放热比指标,对联合储热系统的运行效果进行定量评价,发现水循环系统具有蓄放热速度快的特点,蓄放热比绝对值最高可达1.62,是当天土壤蓄放热的1.8倍。但从总量上看,土壤仍是连阴天主要放热来源,在北京地区联合蓄放热系统能够维持3个连阴天的热量需求。水循环系统平均性能系数(coefficient of performance,COP)为9.16,地中热交换系统平均COP为6.82,联合蓄放热系统综合COP为8.85,对比热泵,其节能率达60.26%。研究结果为联合储热系统蓄放热机理研究提供了理论依据。

粮食平房仓太阳能光伏-地源热泵供冷系统仿真研究与试验

为解决粮食平房仓通风能耗大、储粮成本高的问题,该研究提出太阳能-地源热泵供冷系统,研究太阳能光伏-地源热泵供冷系统在粮食平房仓建筑中的可行性以及节能效果,以实现“零能耗”和“零排放”绿色储粮。基于粮食平房仓实际尺寸,建立了空气源热泵与太阳能光伏-地源热泵供冷系统仿真模型,并通过与仓房实测数据的对比进行了模型验证,从运行性能、光电适配性、经济性、节能以及环保效益等方面对供冷系统进行了分析。结果表明:系统运行1 a后性能系数(coefficient of performance,COP)最大值为4.76,最小值3.3;运行10 a后COP最大值为3.96,最小值3.07;系统年实际发电量与库区用电量之比为192%~270%;投资回收期为7.8 a;与传统空气源热泵系统相比,太阳能-地源热泵供冷系统节能率达59%,研究结果可为粮食平房仓供冷系统优化提供理论依据和设计参考。

天空地一体立体网络的水质遥感监测及其溯源初探——以淀山湖为例

利用卫星遥感、无人机和走航船等手段组成的天空地一体化立体水质监测网络对淀山湖水质进行监测,并对水质参数的空间分布进行溯源分析。结果表明:(1)构建的水质参数反演模型实现了对淀山湖区域高精度的水质反演。其中总磷质量浓度反演结果的均方根误差(RMSE)为0.0191 mg/L,决定系数(R^(2))=0.64(P<0.001);氨氮质量浓度反演结果的RMSE为0.0360 mg/L,R^(2)=0.83(P<0.001);(2)水质空间分布特征为淀山湖总磷和氨氮浓度均表现为西北高,中部和东西低;叶绿素a浓度呈现出北高南低、东高西低及岸边高、中心低的空间分布特征;(3)通过广义线性混合模型对淀山湖水质空间分布进行溯源分析发现,入湖支流、动力船只、农田和水生植物对淀山湖总磷、氨氮和叶绿素a浓度的分布格局均有显著影响,其中入湖支流的影响最大。该研究结果可为上海市水环境立体监测提供重要参考和科学依据。