Fiber optic sensing and performance evaluation of a water conveyance tunnel with composite linings under super-high internal pressures

For long-distance water conveyance shield tunnels in operation,the high internal water pressure may cause excessive deformation of composite linings,affecting their structural integrity and serviceability.However,the deformation and failure characteristics of lining structures under internal water pressure are not well investigated in the literature,particularly for three-layer composite linings.This study presents an in situ experimental investigation on the response of two types of composite linings(i.e.separated and combined lining structures)subjected to internal pressures,in which a fiber optic nerve system(FONS)equipped with distributed strain and displacement sensing nerves was employed to monitor the performance of the two composite linings during testing.The experimental results clearly show that the damage of the tunnel lining under different internal pressures was mainly located in the self-compaction concrete layer.The separated lining structure responded more aggressively to the variations in internal pressures than the combined one.Moreover,two evaluation indices,i.e.radial displacement and effective stiffness coefficient,are proposed for describing the changes in the structural bearing performance.The effective stiffness coefficients of the two types of lining structures were reduced by 39.4%and 29.5%,respectively.Considering the convenience of field monitoring,it is suggested that the average strains at different layers can be used as characteristic parameters for estimating the health conditions of lining structures in service.The analysis results provide a practical reference for the design and health evaluation of water conveyance shield tunnels with composite linings.

Effect of Reference Conveyance Parameter Usage on Real Time Canal Performance: The Case of Fentale Irrigation Scheme in Ethiopia

In designing a canal system, a major problem is to decide what conveyance parameter to apply in the calculations. Since basic knowledge on this subject is lacking, it is usually taken from literatures. Most of the irrigation projects in Ethiopia are found to work below their expectation. One of the main reasons is the conveyance parameters variation from the expected (design) value which ultimately affects the envisioned conveyance efficiency. To evaluate this variation, Fentale irrigation scheme was used as case study. The conveyance efficiency used at the design stage was 80%, which was within Food and Agricultural Organization of the united nations recommendations;while the field survey value was 17%. Such huge variation was due to the fact that the assigned conveyance parameter values (roughness coefficient, hydraulic radius and bed slope) no longer represent the current situation of the scheme. Such variation has resulted in increase in the depth and top width of the water surface which further resulted in 13% and 3% increase in wetted perimeter and top width of the canal, respectively. Thus this study suggests that conveyance parameters shall be derived from history of existing irrigation schemes in a country, rather than adopting it from standard literatures. As such construction quality, maintenance activities and technological transfer activities in a country shall be seen in deciding the conveyance parameters. The study also suggests that the ever increasing water shortage in an irrigation project could be managed by proper maintenance of the entire irrigation system.

The Comparative Study of Chuangtse’s English Translations Under the Theory of Spirit Transmission and Meaning Conveyance

Cultural-loaded word is one of the most popular topics in translation studies.The theory of spirit transmission and meaning conveyance provides a new way for the translation of cultural-loaded word.Based on the A Happy Excursion,this paper makes a comparative analysis of the translation strategies of seven English versions.This study will reveal the similarities and differences between Chinese and foreign translators’translation strategies.

3D Finite Element Simulation of Tunnel Boring Machine Construction Processes in Deep Water Conveyance Tunnel

Applying stiffness migration method,a 3D finite element mechanical model is established to simulate the excavation and advance processes.By using 3D nonlinear finite element method,the tunnel boring machine(TBM) excavation process is dynamically simulated to analyze the stress and strain field status of surrounding rock and segment.The maximum tensile stress of segment ring caused by tunnel construction mainly lies in arch bottom and presents zonal distribution.The stress increases slightly and limitedly in the course of excavation.The maximum and minimum displacements of segment,manifesting as zonal distribution,distribute in arch bottom and vault respectively.The displacements slightly increase with the advance of TBM and gradually tend to stability.

塔里木河下游地下水化学特征对生态输水的响应

结合2000～2002年塔里木河下游5次生态输水过程,通过对沿河40眼地下水监测井采集的水化学资料的分析表明:塔里木河下游地下水化学特征随五次间歇性生态输水发生明显变化。地下水化学对输水的响应表现为初期、中期和后期三个阶段:初期,地下水化学成分中的主要离子含量和矿化度都明显上升;中期逐步下降;输水后期又逐步上升。通过对地下水盐运移机理以及生态输水后地下水化学变化特征的分析得出,单一河道输水方式不如双河道,甚至多河道输水更有利于生态的恢复,另外,生态输水只是对地下水中盐分浓度起到了稀释作用,只有采取一系列工程和管理措施才能使下游水质真正好转。

Land use/land cover change responses to ecological water conveyance in the lower reaches of Tarim River,China

The Tarim River is the longest inland river in China and is considered as an important river to protect the oasis economy and environment of the Tarim Basin.However,excessive exploitation and over-utilization of natural resources,particularly water resources,have triggered a series of ecological and environmental problems,such as the reduction in the volume of water in the main river,deterioration of water quality,drying up of downstream rivers,degradation of vegetation,and land desertification.In this study,the land use/land cover change(LUCC)responses to ecological water conveyance in the lower reaches of the Tarim River were investigated using ENVI(Environment for Visualizing Images)and GIS(Geographic Information System)data analysis software for the period of 1990-2018.Multi-temporal remote sensing images and ecological water conveyance data from 1990 to 2018 were used.The results indicate that LUCC covered an area of 2644.34 km^(2) during this period,accounting for 15.79%of the total study area.From 1990 to 2018,wetland,farmland,forestland,and artificial surfaces increased by 533.42 km^(2)(216.77%),446.68 km^(2)(123.66%),284.55 km^(2)(5.67%),and 57.51 km^(2)(217.96%),respectively,whereas areas covered by grassland and other land use/land cover types,such as Gobi,bare soil,and deserts,decreased by 103.34 km2(14.31%)and 1218.83 km2(11.75%),respectively.Vegetation area decreased first and then increased,with the order of 2010<2000<1990<2018.LUCC in the overflow and stagnant areas in the lower reaches of the Tarim River was mainly characterized by fragmentation,irregularity,and complexity.By analyzing the LUCC responses to 19 rounds of ecological water conveyance in the lower reaches of the Tarim River from 2000 to the end of 2018,we proposed guidelines for the rational development and utilization of water and soil resources and formulation of strategies for the sustainable development of the lower reaches of the Tarim River.This study provides scientific guidance for optimal scheduling of water resources in the region.

Eco-water conveyances applied to control desertification at the lower reaches of the Tarim River

The lower reaches of the Tarim River are one of the areas suffering from most severe sandy desertification in Xinjiang, Northwest China. Irrational utilization of water and land resources results in eco-environmental deterioration in the Tarim River. In May 2000, the local government carried out the water conveyances project in the Tarim River. The influence of water conveyance on desertification reversion is analyzed and discussed according to the monitoring data in the past three years. Based on monitored data of the nine observed sections, along the channel of conveyance, the intensity and scope of desertification reversion in the upper reaches are larger than those in the lower reaches. Dynamic changes of desertification reversion are more obvious from the channel of conveyance to its two sides. However, the range of influence and intensity of desertification reversion is limited at present. It is suggested that the way and range of water conveyances should be adjusted in the future.

我国城市地下空间盾构法隧道工程技术新进展

基于盾构施工特点,对盾构法施工技术的发展过程和创新进展进行调查研究,总结盾构法施工技术在地铁、市政公路、城市铁路、城市水工隧洞、城市综合管廊等工程中的最新应用,阐述城市盾构法隧道在地质条件多样化、越江跨海常态化、结构断面多元化、地面条件复杂化、隧道结构耐久性等方面面临的技术挑战。介绍超大直径盾构装备、大直径泥水盾构常压换刀、多模盾构、类矩形盾构隧道建造、联络通道机械法施工、软硬极端悬殊地层掘进、富水砂卵石地层土压平衡盾构、地下高地震烈度盾构隧道减隔震抗震和超长距离综合施工等技术创新成果;总结不良地质识别、设备状态实时感知、同步推拼连续掘进、盾构自动驾驶技术、盾构智能化管控平台等盾构智能掘进技术进展;指出城市地下空间建设盾构法隧道工程的发展趋势,地铁隧道、城市道路、综合管廊、城市给排水等设施需要不断更新,并网络化,盾构法隧道技术需要不断发展,盾构法隧道智能化施工需日趋精益。未来盾构装备将朝着“多模式、无刀化、外星化”等多元化,多源信息感知、管片智能拼装、地质探测预报、自主感知掘进决策等智能化以及特大直径、超长距离、超大埋深、超高水压等方向发展。

大空间建筑有害气体输运过程研究方法的分析

大空间建筑中有害气体的扩散和输运过程为低速流动(马赫数M<<1),呈不可压缩或弱可压缩(WeaklyCompressible)特性,这类问题的实验研究和数值模拟均存在不少问题和困难。本文分析了此类问题研究方法的现状,系统地分析和比较了场模拟常用数值方法的特点,以及不同湍流模式的适用性。分析表明采用LES的场模拟方法是研究此类问题行之有效的方法,亚格子尺度模型是此类方法应用需重点考虑的因素。

湿陷性黄土区输水隧洞盾构施工风险评估

为了提高针对湿陷性黄土区输水隧洞盾构法施工安全评估的可靠性,从人员管理、机械材料、施工技术、施工环境4个方面构建较为完善的施工安全风险评估指标体系;利用灰色-DEMATEL方法对中心度进行处理得到风险指标权重;以风险发生概率和风险损失程度两个维度为基础构建二维云评估模型,其中发生概率由主、客观方法相结合来确定,损失程度通过改进雷达图法从人员伤亡、经济损失、工期延误、功能缺陷和环境影响5个方面来综合确定。将该评估模型运用到引汉济渭工程X输水隧洞盾构法施工项目的安全评估中。结果表明:该项目施工风险评估等级为Ⅱ级,施工安全风险程度较小,评价结果符合工程实际,验证了该评估模型的可行性和有效性。研究成果可为湿陷性黄土区类似输水隧洞盾构法施工安全风险评估提供借鉴和参考。

双线大直径输水隧道建设对既有桥梁及桩基的影响分析

为准确分析双线大直径输水隧道下穿对既有桥梁结构的影响,构建桥梁-地层-桩基-盾构隧道高精度数值仿真模型,对桥梁桩基结构及盾构过程进行精细化模拟,结合基于智能算法的土层参数反演模型,获取更接近真实情况的土层参数,以提高数值模拟精度。结果表明:输水隧道盾构开挖引起的地表最大沉降量为15.01 mm,基于反演的地表变形计算结果与实际监测值的误差减少约70%;盾构隧道双线开挖会引起地表二次沉降变形,两条盾构隧道中间区域的地表二次沉降量最大,约占总沉降量的60%,最大二次沉降量为5.06 mm;隧道两侧的桩基受到影响较大,最大位移为10.03 mm,位于桩基顶部,而隧道开挖对桩基内应力分布影响较小,可以认为无影响。

基于“木郁达之”理论探析排便障碍型便秘的诊治思路

“木郁达之”理论首见于《黄帝内经》,通过追溯其理论源流发现:“木郁”是对肝脏生理功能失常的高度概括,即肝失疏泄。“达之”是一种治疗原则,目的在于使肝气条达、舒畅。排便障碍型便秘是临床常见病,肝失疏泄作为基本病机贯穿疾病始终,并常伴见脾虚湿阻、肺失宣降、肾阳不足等。临床辨治上以“达之”为治疗原则,针对肝脏自身病变灵活应用养血柔肝、疏肝理气、清肝泻火、温补肝阳,并视患者情况不同予以升阳除湿、肃降肺气、温补肾阳等。

地方政府债务扩张与资源配置效率

地方政府以土地出让收入作为担保和偿债来源能够放大其债务融资能力,而提高市场资源配置效率是实现经济高质量发展的重要支撑。首先,通过构建理论框架,揭示了金融摩擦异质性导致地方政府债务扩张加剧了资源错配;其次,利用中国工业企业数据,结合2009年中央政府放松地方政府债务融资管制这一外生事件,采用双重差分方法,对地方政府债务扩张的资源配置效应进行了实证检验。研究发现:地方政府债务扩张加剧了资源配置效率的损失,这一结论在经历了一系列稳健性检验后仍然成立;机制分析验证了理论框架的假设,即地方政府债务扩张相对更多的提高了民营企业融资成本和资本边际收益产品,进而拉大了部门间价值生产率的离散程度,造成资源错配的加剧;进一步分析发现,地方政府债务扩张引发的资源错配最终降低了加总的全要素生产率。上述结论丰富了现有针对中国地方政府债务经济效应分析的文献,不仅拓展了理论支撑,还提供了详实的经验证据,对防范和化解地方政府债务风险、助推经济高质量发展具有一定的参考价值。

Nonlinear dynamics of a circular curved cantilevered pipe conveying pulsating fluid based on the geometrically exact model

Due to the novel applications of flexible pipes conveying fluid in the field of soft robotics and biomedicine,the investigations on the mechanical responses of the pipes have attracted considerable attention.The fluid-structure interaction(FSI)between the pipe with a curved shape and the time-varying internal fluid flow brings a great challenge to the revelation of the dynamical behaviors of flexible pipes,especially when the pipe is highly flexible and usually undergoes large deformations.In this work,the geometrically exact model(GEM)for a curved cantilevered pipe conveying pulsating fluid is developed based on the extended Hamilton's principle.The stability of the curved pipe with three different subtended angles is examined with the consideration of steady fluid flow.Specific attention is concentrated on the large-deformation resonance of circular pipes conveying pulsating fluid,which is often encountered in practical engineering.By constructing bifurcation diagrams,oscillating shapes,phase portraits,time traces,and Poincarémaps,the dynamic responses of the curved pipe under various system parameters are revealed.The mean flow velocity of the pulsating fluid is chosen to be either subcritical or supercritical.The numerical results show that the curved pipe conveying pulsating fluid can exhibit rich dynamical behaviors,including periodic and quasi-periodic motions.It is also found that the preferred instability type of a cantilevered curved pipe conveying steady fluid is mainly in the flutter of the second mode.For a moderate value of the mass ratio,however,a third-mode flutter may occur,which is quite different from that of a straight pipe system.

高效低压钻井液系统研制与应用

为了满足科威特地区9000 m超深井钻机的作业需求,研发了高效低压钻井液系统。该系统比同级别系统安全性高、工艺流程复杂、环境更友好,可同时满足水基钻井液、油基钻井液作业工况。首次在9000 m超深井钻机配套的低压钻井液系统上应用节能型搅拌器、多功能螺旋输送机、双机械密封离心泵,使得低压钻井液系统更加节能、环保。该系统采用双通道工艺流程,双层钻井液罐设计罐面通道更为顺畅。厂内试验结果表明,该系统噪声低于82 dB,设备轴承温升不高于32℃,工艺流程正常,满足设计要求。随钻机开展了2 h的设备运转试验和2 h的联调试验,低压钻井液系统工作稳定正常。研究成果丰富了钻机产品的多样性,可广泛应用于科威特、阿联酋、沙特等中东地区超深井作业。

渗流-应力耦合作用下穿断层破碎带TBM输水隧洞结构安全研究

为分析敞开式隧道掘进机(TBM)穿越断层破碎带深埋长输水隧洞围岩的稳定性及其支护结构的安全性,依托东庄水利枢纽北线输水隧洞工程,采用ABAQUS软件建立隧洞开挖过程渗流-应力耦合三维动态施工仿真模型,研究了隧洞开挖支护过程中断层破碎带处围岩的稳定性和支护结构的受力特性及其变化规律。结果表明:隧洞围岩由于卸载作用其孔隙度最大值较初始状态增大了0.88%,渗透系数最大值较初始状态增大了2.59%;隧洞围岩孔隙水压力随开挖支护过程先下降—再平缓—最后回升至稳定;围岩塑性区出现在沿径向1 m范围内,等效塑性应变极值出现在围岩腰线处;锚杆应力在衬砌进行支护时达到峰值,其最大值为182.90 MPa;衬砌内、外缘均处于受压状态,衬砌环向应力值随开挖支护过程先出现最大值,随后略微减小至稳定,其值在6.66~11.92 MPa范围内;衬砌的变形整体上表现为向内收缩,收缩量从顶拱和底拱处向腰线处逐渐减小,其值在0.67~1.35 mm范围内;随着排水量的增加,围岩最大径缩量逐渐增大,衬砌外水压力折减系数逐渐减小。研究结果可为穿断层破碎带TBM隧洞工程结构设计及其安全施工和运营提供参考依据。

Predictive analysis of stress regime and possible squeezing deformation for super-long water conveyance tunnels in Pakistan

The prediction of the stress field of deep-buried tunnels is a fundamental problem for scientists and engineers. In this study, the authors put forward a systematic solution for this problem. Databases from the World Stress Map and the Crustal Stress of China, and previous research findings can offer prediction of stress orientations in an engineering area. At the same time, the Andersonian theory can be used to analyze the possible stress orientation of a region. With limited in-situ stress measurements, the Hock-Brown Criterion can be used to estimate the strength of rock mass in an area of interest by utilizing the geotechnical investigation data, and the modified Sheorey＇s model can subsequently be employed to predict the areas＇ stress profile, without stress data, by taking the existing in-situ stress measurements as input parameters. In this paper, a case study was used to demonstrate the application of this systematic solution. The planned Kohala hydropower plant is located on the western edge of Qinghai-Tibet Plateau. Three hydro-fracturing stress measurement campaigns indicated that the stress state of the area is SH - Sh 〉 Sv or SH 〉Sv 〉 Sh. The measured orientation of Sn is NEE （N70.3°-89°E）, and the regional orientation of SH from WSM is NE, which implies that the stress orientation of shallow crust may be affected by landforms. The modified Sheorey model was utilized to predict the stress profile along the water sewage tunnel for the plant. Prediction results show that the maximum and minimum horizontal principal stres- ses of the points with the greatest burial depth were up to 56.70 and 40.14 MPa, respectively, and the stresses of areas with a burial depth of greater than 500 m were higher. Based on the predicted stress data, large deformations of the rock mass surrounding water conveyance tunnels were analyzed. Results showed that the large deformations will occur when the burial depth exceeds 300 m. When the burial depth is beyond 800 m, serious squeezing deformations will occur in the surrounding rock masses, thus requiring more attention in the design and construction. Based on the application efficiency in this case study, this prediction method proposed in this paper functions accurately.

TBM有压输水隧洞内张钢圈-管片-围岩组合结构联合承载力学特性分析

为探究全断面隧道岩石掘进机(tunnel boring machine,TBM)有压输水隧洞内张钢圈-管片-围岩组合结构的受荷状态,以榕江―关埠引水工程中Ⅴ类围岩TBM有压输水隧洞段为研究对象,建立内张钢圈-管片-围岩组合结构三维精细化有限元模型,研究内水压力、围岩类型对组合结构力学特性的影响。研究结果表明:采用内张钢圈加固隧洞结构能有效控制隧洞变形,减小管片拉应力及受拉区范围,提高组合结构的承载能力;内水压力作用下管片压应力、竖向变形、接缝张开度、连接螺栓应力、内张钢圈应力、锚杆应力均较无内水压力作用下有所减小,但管片拉应力和接缝错台分别增大了19.68%、39.25%,其主要原因为内水压力作用致使隧洞结构整体呈现向外膨胀,在充水运营期间应加强内水压力作用下的安全监测;在外部水土压力和内水压力共同作用下,围岩类型的改变使组合结构中连接螺栓应力、管片接缝错台、锚杆应力分别提高37.11%、15.29%、14.75%,其主要原因为围岩岩性越差承担荷载能力越弱,在围岩类型的过渡区域应进行重点监测;此外,在外部水土压力和内水压力共同作用下,组合结构中围岩、管片、内张钢圈、锚杆的荷载分担率分别为21.38%、43.08%、24.01%和11.53%,内张钢圈荷载分担率较无内水压力作用提高了34.06%,内水压力作用提高了内张钢圈分担荷载的效果;组合结构中围岩的分担率随围岩类型(Ⅲ类、Ⅳ类、Ⅴ类)的增加而减小,相同荷载下Ⅲ类围岩的荷载分担率较Ⅴ类围岩提高了16.96%。该研究成果可为类似隧洞工程的衬砌设计及后期加固措施提供理论参考。

乌江三桥620kN缆索吊机的设计

乌江三桥位于重庆市彭水县乌江上,采用主跨为140m的钢筋混凝土等截面悬链线无铰箱形拱,拱肋纵向分7段预制安装。缆索吊机采用塔架为固结,塔顶索鞍为可移动式,一侧用预应力锚索结构作为主锚碇。主要介绍缆索吊机设计,以及笔者的体会和建议。

南水北调中线工程输水建筑物整流累积效应研究

为分析输水建筑物整流对南水北调中线工程输水能力的影响,以陶岔渠首闸至十二里河渡槽渠段为例,建立一二维耦合水动力模型,其中渠道段采用一维模型,4个输水建筑物段(刁河渡槽、湍河渡槽、严陵河渡槽和淇河倒虹吸)采用二维模型,利用多年实测数据对耦合模型进行率定。分别对无整流方案和15种整流方案进行模拟计算,分析不同整流方案对上下游的影响,进而确定水头损失最小的整流方案。结果表明:单体整流影响范围为建筑物上下游3~5 km,多个建筑物整流的累积效果小于单个建筑物整流效果的线性叠加;对渠段中间2个输水建筑物(湍河渡槽、严陵河渡槽)进行整流的效果优于对上下游2个输水建筑物(刁河渡槽、淇河倒虹吸)进行整流的效果。