隧道挖装机的功能拓展研究

针对施工现场对隧道挖装机在工作中的要求,增加了挖装机集料斗的推铲功能,以提高其装渣作业的效率。考虑到作业中可能遇到粉尘飞扬带来的危害,增加了喷雾降尘功能。提出了实现这些功能的方案,对其进行理论分析和相关计算,并用MATLAB软件对参数进行优化,确保功能的可靠性。     

清管过程中隧道内输气管道应力分析

清管是保证管道能够长期在设计输量下安全运行的基本措施之一,清管过程大致分为试压后清管和正常工况下清管两部分。我国大部分天然气管道分布在丘陵、山地等地形起伏较大的地区,清管模型大多没有考虑地形起伏或高差对清管模型的影响。受力模型与管内的清管器运动有直接关联,只有建立合适的清管器运动瞬态模型,并与清管过程中输气管道受力模型相结合,才能较为准确地模拟出实际的应力状况并定量给出清管对管道的影响,以期指导清管作业。     

The Golden Age: Between Wilderness and Utopia

Artist Dominic Shepherd pursues the imaginative and a sense of mystery in his work; his 2012 one-man show at Charlie Smith London was entitled ‘Jerusalem’. Here he reflects on the Golden Age as depicted in Cranach's masterpiece of that name, and ruminates on the cyclical nature of the pastoral, a landscape that is tended and nurtured by generations of hands.     

大型沉管隧道混凝土裂缝控制技术

对上海外环沉管隧道这一横断面规模居亚洲第一世界第三的管段结构制作施工技术作了介绍,并着重从大型沉管混凝土裂缝控制技术角度进行了理论和实践的针对性分析。其技术措施及分析方法对类似工程施工有借鉴作用。     

Effect of Poisson''s ratio on the normalized radial displacements occurring around the face of a circular tunnel

The distribution of displacements occurring around the advancing face of a tunnel is one of the widely discussed topics in tunnelling. Unavailability of a closed-form solution for this problem has directed the researchers to the utilization of numerical analyses mainly. In this study, a three-dimensional finite difference stress analysis program, i.e. FLAC^3D, has been employed for determining the variation of radial boundary displacements along the longitudinal direction of a circular tunnel located in a hydrostatic in situ stress field. According to the results for a linear elastic material behavior, the normalized radial displacements occurring in the vicinity of the face are affected by Poisson's ratio of the surrounding medium. In addition, it has been noted that, depending on Poisson's ratio, the value of elastic pre-deformation occurring at the face ranges between 20 and 30% of the final tunnel deformation occurring far from the face. Furthermore, expressions obtained by non-linear curve fitting are presented for the normalized radial displacements occurring ahead of and behind the excavation face of the tunnel.     

Effects of steel fiber reinforced high-strength shotcrete in a squeezing tunnel

In order to quantitatively clarify the effects of steel fiber reinforced high-strength shotcrete (SFRS) applied to a squeezing tunnel, a non-linear numerical analysis is carried out, in which the stress–strain–time constitutive relationships of SFRS and the time-dependent movement of the ground surrounding the tunnel are taken into account. Through a comparison of field measurement and analytical results, it is recognized that SFRS can be applied as a reasonable primary lining for tunnels excavated in grounds with severe geological conditions. In particular, high strength during the early stages of the execution and ductility after its peak strength both contribute to the safe construction of squeezing tunnels.     

复合高效型液态速凝剂在保宜高速公路隧道中的应用研究

喷射混凝土是隧道工程施工中必不可少的一种支护方式,其中速凝剂对喷射混凝土质量影响很大。提出一种新型的复合型高效液态速凝剂,是由多种组分复合而成,具有掺量少、适应性强、后期强度损失小等特点。一般掺量为水泥质量的1.5%～3%,初凝时间在1min左右,终凝时间在4min以内,混凝土后期强度损失率在10%以内。经过实际隧道工程试验,表明该速凝剂具有回弹小,无落浆等优点,是一种较为理想的喷射混凝土用液态速凝剂。     

Machine learning-based classification of rock discontinuity trace: SMOTE oversampling integrated with GBT ensemble learning

This paper presents a hybrid ensemble classifier combined synthetic minority oversampling technique (SMOTE), random search (RS) hyper-parameters optimization algorithm and gradient boosting tree (GBT) to achieve efficient and accurate rock trace identification. A thirteen-dimensional database consisting of basic, vector, and discontinuity features is established from image samples. All data points are classified as either “trace” or “non-trace” to divide the ultimate results into candidate trace samples. It is found that the SMOTE technology can effectively improve classification performance by recommending an optimized imbalance ratio of 1:5 to 1:4. Then, sixteen classifiers generated from four basic machine learning (ML) models are applied for performance comparison. The results reveal that the proposed RS-SMOTE-GBT classifier outperforms the other fifteen hybrid ML algorithms for both trace and non-trace classifications. Finally, discussions on feature importance, generalization ability and classification error are conducted for the proposed classifier. The experimental results indicate that more critical features affecting the trace classification are primarily from the discontinuity features. Besides, cleaning up the sedimentary pumice and reducing the area of fractured rock contribute to improving the overall classification performance. The proposed method provides a new alternative approach for the identification of 3D rock trace.     

Direct Tunnel技术研究及引入策略探讨

介绍了UMTS网络中Direct Tunnel的网络架构特殊参数和关键流程的处理。详细分析了Direct Tunnel的各种优劣势及Direct Tunnel的部署对网络可能产生的各种影响,并根据分析结果给出合理Direct Tunnel的引入策略建议及部署方案。     

以太网测控系统的架构设计与研究

针对基于以太网通讯的测控系统（Ethernet-based Control System,ECS）各种应用的共有特性与诸多变化点,如不同种类的通用通讯协议的选择,通讯数据包结构的复杂性与随机性,对通讯数据后续处理需求的不确定性等,利用面向对象的设计思想,抽象共性,封装变化点,建立一种针对此类系统的具有良好性能、灵活性与可扩展性且简洁的系统架构设计。该设计在风洞测控系统（Wind Tunnel Control System,WTCS）中的实际应用表明其确实可行。