Effects of circumferential pick spacing on boom type roadheader cutting head performance

Effects of equal and unequal circumferential pick spacing on the performance of boom type roadheaders having cylindrical cutting heads are investigated. For this purpose, two experimental cutting heads with equal and unequal circumferential spacing are designed and manufactured. The cutting head with unequal circumferential spacing is specifically designed to prevent tool-holder overlap at the nose section. Manufacturing difficulties associated with equal circumferential pick spacing due to tool-holder overlap are discussed with solid modeling and practical applications. The heads are tested at Park Cayirhan Coal Mine in Turkey and their cutting performances are analysed. Although better cutting performance for equal circumferential spacing are predicted by force–balance analysis, in situ measurements of instantaneous (net) traversing speed and cutting rate, pick consumption rate and machine vibration show that no significant difference exists between the performances of the two cutting heads.     

The effect of machine design parameters on the stability of a roadheader

A “roadheader” excavator has a special set of characteristics among tunnel excavation machines and the determination of the stability states of a roadheader is important for effective and continuous excavation. For roadheaders having equal power, if one is more stable than another, it can respond to higher boom forces. A new computer program was developed to analyze the stability states of roadheaders. The developed method allows analysis for both longitudinal and transverse cutting head type machines either at one point on the excavation face or in terms of the whole face. Values of the four stability states of the roadheader, namely: turning around the vertical axis, turning to the side directions, turning to the back direction and sliding, can be obtained using this program. In this study, the effects of machine design parameters were investigated by applying this method to the stability of a longitudinal type roadheader. The studied machine design parameters are the machine weight, boom length, machine width, track width, distance between the back leg of the machine and the center of gravity, distance between the start of the boom and the center of gravity, distance between the horizontal point and the vertical rotation point of the boom, and the distance between the ground and boom axis when it is parallel to the ground. The effect of the machine design parameters on stability has been illustrated in detail.     

Some geological and geotechnical factors affecting the performance of a roadheader in an inclined tunnel

The factors affecting the performance of 90 kW-shielded roadheader is investigated in detail in a tunnel excavated for Nuh Cement Factory. The first part of the tunnel is horizontal and the second part is inclined with 9° and excavated uphill. Tunnel passes through a formation of the Upper Cretaceous age with nodular marl, carbonated claystone, thin and thick laminated limestone. Water ingress changes from 0 to 11 l/min. In six different zones it is found that the rock compressive strength changed from 20 to 45 MPa, tensile strength from 1 to 4 MPa, specific energy from 11 to 16 MJ/m³, plastic limit from 15% to 29%, liquid limit from 27% to 43% and water absorption from 4% to 18% in volume.

Detailed in situ observations show that in dry zones for the same rock strength the inclination of the tunnel and the strata help to increase the instantaneous cutting rate from 10 to 25 solid bank m³/cutting hour. The effect of water on cutting rate is dramatic. In the zones where the plastic limit and the amount of Al₂O₃ is low, instantaneous cutting rate increases from 34 to 50 solid bank m³/cutting hour with increasing water content from 3.5 to 11 l/min. However, in the strata having high water absorption characteristic and high amount of Al₂O₃, cutting rate decreases considerably due to the sticky mud, causing problem to the cutterhead. Excavation, muck loading and support works are performed separately due to safety concerns in the wet and inclined sections which reduced the machine utilization time from 38% to 8%. The information gathered is believed to form a sound basis in contributing the performance prediction of roadheaders in difficult ground conditions.     

不同加载速率下钢筋混凝土梁力学性能试验研究

利用MTS电液伺服试验系统对钢筋混凝土梁进行不同加载速率下的力学性能试验,采用位移控制的单调加载方式,加载速率分别为0.1mm/s、0.5mm/s、1.0mm/s、5.0mm/s和10.0mm/s,研究加载速率对钢筋混凝土梁力学性能的影响,分析加载速率对钢筋混凝土梁破坏形式、荷载-变形曲线的影响,及加载速率对钢筋混凝土梁的开裂、极限、破坏荷载,开裂、极限、破坏位移以及延性和耗能能力的影响。结果表明：随着加载速率的提高,钢筋混凝土梁的裂纹分布更加均匀,且宽度逐渐减小;钢筋混凝土梁的开裂、极限、破坏荷载,开裂、屈服、极限位移和位移延性系数都随着加载速率的增加明显增大;随着加载速率的增加,钢筋混凝土梁的耗能能力得到显著提高。     

挤压式边墙技术在面板堆石坝工程中的应用

结合工程实例,提出了采用混凝土挤压式边墙护坡技术作为该电站面板堆石坝上游坡面施工的新方法,对挤压式边墙技术指标及施工方法进行了介绍,并阐述了挤压式边墙的施工特点,最后对其进行了质量检测,以推广该技术的应用。     

浴室干燥热泵热水器实验研究

设计了一款具有除湿功能的浴室干燥热泵热水器,分析了系统结构和工作原理。对不同运行模式的实验研究表明,该热水器在节能与功能方面具有独特的优势。     

Flexible design of a rock slope abutment at the Wuqiangxi Hydroelectric Power Station

This paper presents the results of the real-time monitoring of a rock slope at the abutment of the Wuqiangxi Hydroelectric Power Station, Hunan Province, China, and the ensuing modifications of the original design and excavation process. Monitoring sites were carefully selected based on information collected on geological features (for example, faults) and from the results of numerical modelling. A flexible approach to the design was taken, using feedback from the monitoring system which allowed (1) time to set up support/remedial measures during the work and (2) a reduction in the use of pre-stressed anchored cables. As a consequence, the work was successfully carried out with cost savings and no safety problems.

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Résumé Cet article présente les résultats d’auscultation d’une pente rocheuse au niveau d’ouvrages de soutènement pour la centrale hydroélectrique de Wuqiangxi (province de Hunan, Chine). Cette surveillance en temps réel a permis des modifications du projet initial et des procédés d’excavation. Les sites instrumentés ont été soigneusement choisis en fonction du contexte géologique et des failles présentes, tout en prenant appui sur des résultats de simulation numérique. Une conception d’ouvrage capable d’adaptation a été définie, utilisant les informations en retour de l’auscultation, ce qui a permis a) de mettre en oeuvre des mesures de soutènement en temps voulu et b) de limiter l’utilisation de câbles précontraints. En conséquence, les travaux ont été réalisés avec succès, des économies étant réalisées et les problèmes de sécurité maîtrisés.

     

旋风除尘器下降流量的研究

通过实验测定了常规旋风除尘器内下降流量铅高度的分布,发现在排气芯管入口断面附近有约２４％的短路流量,测定了安装不同类型减阻杆后的下降流量,发现非全长减阻杆下端固定时,有增加减阻杆上方断面下降流量的功效,这将延长含尘气流在除尘器内的停留时间,提高除尘效率。     

不同加载速率下CFRP加固混凝土梁动态力学性能试验研究

混凝土动态力学行为具有明显的率相关性,为此对CFRP加固混凝土梁试件开展了4种加载速率(0. 1、0. 01、0. 001 mm/s和0. 000 5 mm/s)下的力学性能试验,通过位移控制的单调加载方式研究不同加载速率对CFRP加固混凝土梁试件的破坏过程、荷载-裂缝张口位移曲线、断裂能和延性指数的影响。基于实时、动态的声发射无损检测技术,对不同加载速率下CFRP加固混凝土梁断裂过程中的声发射参量进行识别和采集,从声发射角度分析了CFRP加固混凝土梁的受力特性。结果表明:低加载速率下,试件侧面预制缝附近伴有其他裂缝产生,且加载速率越低,其裂缝越明显; CFRP加固混凝土梁的开裂、极限、破坏荷载随加载速率的提高而增大;随着加载速率的提高,CFRP加固混凝土梁的断裂能和延性指数均明显增大;声发射累积振铃计数随加载速率的提高而增大。     

基于不同黏结材的CFRP链-混凝土#br# 界面黏结性能试验研究

为研究碳纤维增强复合链(CFRP Strand Sheet)与混凝土的界面黏结性能,共制作8组共24个试件并进行拉伸双剪试验,观测各组试件的破坏形态和应变分布规律,分析CFRP链与混凝土界面的黏结破坏机理,研究不同黏结材的力学性能和CFRP链加固层数对CFRP链 混凝土界面的剪切应力传递和黏结性能的影响。研究结果表明：CFRP链与混凝土的双剪试件均为表层混凝土的剪切破坏,随着CFRP链加固层数的增加,试件的剥离承载力增大,而CFRP链最大应变和界面断裂能均减小;当采用环氧树脂(EP)为黏结材时,CFRP链的材料利用率较大,而采用聚合物水泥砂浆(PCM)为黏结材时,虽单层CFRP链与混凝土界面间具有较优的抵抗剥离能力,但双层加固时,CFRP链的材料利用率却大幅降低。基于现有FRP片材 混凝土的双线性黏结滑移模型,并考虑CFRP链加固层数和黏结材力学性能的影响,建立了相应的界面黏结-滑移模型。     

相同建筑相同节能措施在不同气象条件下的负荷减少率

以广州、重庆、北京等12个城市为对象,分别以DOE-2中的TMY2,DeST—h中的TRY及修改的TMY2辐射数据,构建了36组完全不同的8760h气象数据库。利用特征温度法模拟计算相同建筑在围护结构改进前后单位建筑面积的全年空调和供暖耗能量。研究发现,对所涉及的城市,尽管因三种气象数据库（36组）显著不同,导致计算出的围护结构改进前后（72组）建筑全年空调供暖负荷、负荷减小量存在很大的差异,但是在不同气象条件下对模型建筑采取相同的节能措施。各城市全年空调负荷减小率（节能率）是相近的;各个城市全年供暖负荷减小率（节能率）也是相近的。从而证明了现行各国标准均规定围护结构K限值的通常做法是完全正确的。     

Experimental investigations on the crush behaviour of AA6061-T6 aluminum square tubes with different types of through-hole discontinuities

An experimental investigation was conducted to compare the crush characteristics and energy absorption capacity of AA6061-T6 aluminum alloy extrusions with centrally located through-hole discontinuities. Three different types of geometrical discontinuities, namely, circular, slotted and elliptical holes were fabricated into AA6061-T6 extrusions which had a length of 200 mm, nominal side width of 38.1 mm and wall thickness of 3.15 mm. Furthermore, three different major axis lengths (7.14, 10.72, and 14.29 mm) and three different aspect ratios (1.33, 2.0, and 3.0) of the slotted and elliptical discontinuities were considered. It was found that by introducing crush initiators into the structural members, a splitting and cutting deformation mode was generated rather than global bending deformation which was observed for specimens without any discontinuities. The peak crush load was reduced by incorporating the through-hole crush initiators within a range of 5.2–18.7%, and total energy absorption was increased within a range of 26.6–74.6%. The most significant improvement was noted in the crush force efficiency, which was increased within the range of 54.5–95.8%. For specimens with discontinuities which had a major axis length of 7.14 mm the peak crush load and total energy absorption was independent of initiator geometry and aspect ratio. However, for specimens which had discontinuities with a major axis length of 10.72 and 14.29 mm and an aspect ratio of 3, a geometrical influence on the peak crush load and total energy absorption was apparent.     

Effects of soil on the energy response of equipment–structure systems with different connection types between the equipment and structure

In equipment–structure systems, the soil–structure interaction and connection types between the equipment and structure significantly affect the seismic response. To understand this effect, in this study, the motion equation of an equipment–structure–soil system was derived, and energy balance equations for each part of the coupled system were obtained. Further, the effects of the soil on the energy response were analyzed based on the results of shaking table tests of an equipment–structure system and real‐time substructure shaking table tests of equipment–structure–soil systems with different connection types. The energy response of the equipment–structure system with a rigid ground was compared with that of the equipment–structure–soil systems. The analysis results showed that the energy response of the equipment–structure–soil system with different connections was quite different from that of the system with a rigid ground. The soil decreased the total energy input to the equipment and structure and significantly changed the time distribution characteristics of the input energy. Additionally, the soil weakened the energy consumption of the connections. Therefore, the influence of the soil should be considered in the design of equipment–structure systems with connections.     

被动优先的绿色建筑设计探析——以深圳建科院大楼及山东建筑大学教学实验综合楼为例

在"绿色建筑"技术飞速发展的今天,灵活应用并全面协调好各种现代技术为具体设计与实施的项目服务是当今绿色建筑设计的发展方向。充分利用自然环境条件,注重建筑本身的实际能耗,釆用被动优先的节能措施并辅助主动节能技术的建筑方案才是绿色建筑的根本。在当前"绿色建筑"和"生态建筑"往往不节能、不绿色的背景下,如何通过被动优先的设计理念与主动技术的结合来使建筑真正变为可以顺应时代发展要求的可持续性建筑,是广大建筑设计实践者一直崇尚并追求的发展目标。从以"被动优先"概念为先导的绿色建筑设计出发,通过论述被动式设计的概念、被动优先的设计策略以及对深圳建科院大楼与山东建筑大学教学实验综合楼进行案例分析,来探求以被动式设计策略为出发点的当代绿色建筑的设计思路,以此为今后的绿色建筑设计实践提供借鉴与帮助。     

泥石流拦砂坝坝基土颗粒级配对扬压力影响实验研究

颗粒级配是影响坝基渗透的重要因素,并影响扬压力的大小和分布特征。采用自制装置对不同颗粒级配的6种土样进行坝基渗透实验和竖向渗透实验,研究了细颗粒含量和最小粒径对坝基渗透和扬压力分布的影响,并建立了细颗粒含量与坝基渗透系数和扬压力之间的关系。研究结果表明:坝基土细颗粒含量530%P40%时,最不易发生沉降变形和渗透变形;不同颗粒级配下坝基扬压力沿中轴线均呈线性衰减;坝基土发生渗透变形前扬压力折减系数与渗透系数存在对数变化关系,与细颗粒含量呈线性负相关关系,渗透变形后,扬压力出现大幅波动。     

水下大直径泥水盾构刀盘面板冲刷系统设计研究

苏通管廊越江隧道工程是我国近几年较为典型的水下大直径泥水盾构工程,盾构穿越地层以淤泥质黏土、粉质黏土、粉土、粉细砂等地层为主,在掘进过程中较易结成泥饼。文章依托于苏通管廊越江隧道工程,基于刀盘面板冲刷仿真模型实验,分析刀盘掌子面区域的流场分布特性,提出刀盘冲刷喷头数量和位置的优化设计方案。通过现场冲刷试验分析表明采用该刀盘面板冲刷系统,冲刷效果较好,可以保证刀盘中心冲刷区域及开口的流畅性。通过现场掘进实验分析表明在掘进过程中及掘进贯通完成后并没有出现结泥饼现象,刀盘中心冲刷系统的设计可满足工程需求,达到较优的冲刷效果。     

某底层框架砖房的消能减震设计

研究了底层框架砖房采用消能减震技术的抗震设计方法,介绍了宿迁某底层框架砖房采用粘弹性阻尼器的消能减震设计,给出了多遇地震和罕遇地震作用下的主要计算结果。计算表明,设置粘弹性阻尼器后,上部结构在多遇、罕遇地震作用下均能满足承载力与变形的要求。     

Experimental analysis of control loops with different delay times in the supply air system of a radiator test rig

The test rig of low-temperature hot-water radiator is a typical multi-input multi-output (MIMO) thermal system with large time delay. Aiming at the control of the supply air temperature and the temperature of the environmental chamber in the test rig, the paper carries out the fuzzy control experiments and PI control experiments based on adjusting the electric heater in the supply air system, in which there are two control loops with various delay time. The experiments researched two types of fuzzy control methods which are the basic fuzzy control (BFC), and the self-organizing rules fuzzy control (SORFC) with zero initial control rules. For the control loop of supply air temperature with short delay time, PI control performs better with fast convergence speed and small overshoot than the BFC and the SORFC. The convergence speed of the BFC method is lower than other two control methods. For the control loop of chamber temperature with long delay time, the SORFC has a satisfied control performance with less overshoot and stable error than the BFC and PI control.     

Assessing the total energy impact of manual and optimized blind control in combination with different lighting schedules in a building simulation environment

In this work, we investigated the interplay and the influence of lighting and blind control models on the heating, cooling, and lighting energy loads of an office room. By including different stochastic models for occupancy and appliances, we built a complete simulation environment based on the building simulation program IDA ICE. For control models, we implemented different strategies, including a simple on/off scheme, a realistic model of occupants, and an optimized control. In literature, the results are often compared with simple on/off schemes, which are not hard to beat in terms of performance. With an optimal control, the real saving potential is assessed, which can be used as benchmark case for comparison with other control models. Results based on annual simulations show that active occupants can reduce energy consumption by up to 50% from a worst-case scenario, whereas advanced controllers can further reduce the consumption by another 60%.