基于大样本的强透水砂层盾构施工风险与控制研究

基于大量强透水砂层盾构施工工程事故现场调研及资料分析,建立大样本数据库并构建强透水砂层盾构施工风险事故树,以分析风险源及各自权重;基于模糊综合评价法探究强透水砂层盾构施工风险评估方法,推导出各风险因素对风险发生概率和损失的评价矩阵,从机理控制层面提出风险控制措施,并以广州某强透水砂层盾构工程实施验证。研究表明,施工风险主要为管片破裂、隧道上浮、渣土喷涌及地表塌陷等,风险发生概率与相应损失程度均可划分为5个等级。可通过加强管片拼装质量、改善上覆土层工程特性、渣土改良及装置改进等风险规避策略,有效控制施工风险,并结合风险规避、保留及转移等3种策略对地表塌陷风险进行有效控制。     

东非大裂谷山岭隧道地质灾害熵权可拓物元法评价及风险控制

东非大裂谷火山、地震、断层移动和地裂缝等地质作用活跃,严重威胁隧道安全,有必要研究裂谷内山岭隧道地质灾害破坏.通过系统分析东非大裂谷山岭隧道地质灾害风险源,建立了4类22项风险评价指标体系以及裂谷内山岭隧道地质灾害风险熵权可拓物元方法评价方法,开发了相应的风险安全可视化程序,得到东非大裂谷山岭隧道地质灾害破坏等级,提出...     

改进的AHP对连拱隧道渗漏水病害影响因素评价

本文深入分析了改进的AHP的优点,在现场调研的基础上考虑了18个影响连拱隧道渗漏水病害的因素,测算各因素的权重,最终以杭徽高速公路隧道群渗漏水病害为例,对各影响因素权重系统进行了测算并对其影响的大小进行排序.研究结果显示,连拱隧道的结构形式是影响连拱隧道渗漏水最主要的因素,这种形式的中隔墙自身的缺陷所在使得渗漏水尤为严重,此外,施工也是不可忽视的一个因素,"三缝"施工、防水板施工、排水管施工以及防水材料的选取,都应做到精心施工,严格按照要求,只要一个因素出现问题,渗漏水病害发生的几率就会增大.因此,改进的AHP分析连拱隧道渗漏水病害影响因素的权重系统符合客观实际,给连拱隧道渗漏水影响因素的评价提供了新的思路.     

TGP超前预报数据采集关键技术研究

近年来,国内外隧道建设向更深、更长、更大的方向发展,为减小隧道建设过程中突水突泥、塌方等地质危害带来的影响,隧道超前地质预报工作至关重要,TGP超前预报技术则作为国内技术最先进、运用最广泛的代表之一.本文针对TGP数据采集过程中可能导致地震数据质量较差的因素,通过理论分析、正演模拟、工程应用等研究方法,对TGP超前预报数据采集关键技术开展了相关研究工作.最终归纳出了一套适用于大多数隧道工程的TGP超前预报数据采集工作指南,有助于提高TGP预报精度,保障隧道施工安全.     

高压富水区隧道超前地质预报应用研究

隧道施工过程中,经常遇到突水、突泥和坍塌等无法预料的地质灾害,给施工安全带来了重大灾难和无法估计的经济损失,为了保证隧道施工安全,对不良地质体的发育情况进行准确及时的超前预报,是当前隧道设计与施工中亟待研究与解决的关键问题.详细介绍了TSP-203超前预测预报原理及方法,针对渝宜高速公路某隧道复杂的地质条件,在施工过程中进行了超前地质预测预报,并对预报结果进行了较为详细的处理和分析,同时根据隧道施工现场高压区富水层等地质情况,对隧道外水荷载计算方法和衬砌设计结构进行了分析.结果表明,预报成果与实际情况基本吻合,有效地指导了隧道施工.     

在役隧道震害综合承灾度评价

为客观评价在役隧道震害综合承灾情况,从隧道震害危险性的压力指标与隧道自身及所处工程环境的承压指标筛选具有代表性、可操作性的分级指标。以隧道承灾系统为研究主体,运用最小偏差法将主、客观权重集合,得到评价指标的组合权重,并利用GRA-TOPSIS法对在役隧道震害综合承灾度进行评价,确定隧道震害承灾情况。选取新疆某3个隧道中的5个区段为研究对象,运用GRA-TOPSIS法构建的隧道震害综合承灾度评价模型确定隧道震害承灾等级,评价结果与现场调查结果趋于一致。对影响承灾度的主要因素进行分析,可为各区段制定适宜的修复策略提供参考。     

化工园区重大事故风险分析

目前我国对化工园区风险分析的理论研究尚处于起步阶段。针对化工园区这一特殊区域,从整体角度出发,分析研究了化工园区内多个重大事故风险源造成的区域风险,并进行了实例应用。综合考虑多个重大事故风险源产生的风险,分析了其产生风险的叠加效应,绘制出化工园区的个人风险等值线;同时根据ALARP（合理可接受风险水平）准则对化工园区的风险水平进行评估,并据此给出化工园区安全规划、风险控制和应急救援工作的实施建议。所提出的化工园区重大事故风险分析方法,在建立和完善化工园区风险分析中具有一定的理论和现实意义。     

CSAMT法在某铁路隧道勘察中的应用研究

可控源音频大地电磁法(controlled source audiofrequency magnetotelluric,CSAMT)由于其相较于其他物探方法具有探测深度大、不受高阻层屏蔽、横向分辨率高等优点而被逐渐应用到铁路隧道勘察当中.本文介绍了CSAMT法的方法原理及工作方式,以红豆山隧道为例进行研究,在充分了解测区的地质地球物理的条件下设计合理的观测系统,并对原始数据进行分析处理之后进行带地形的二维反演.根据获得的电阻率剖面对隧道分段进行地质解释分析,为钻孔布设及隧道设计、施工提供基础依据.     

基于多层次可拓评价法的城市燃气管线风险评价研究

以改进的肯特危险指数评分法对城市燃气管道的危险因素进行识分析,确立了城市燃气管线风险评价指标体系。将传统的可拓学方法改进为多层次可拓评价法,对其中的节域物元、关联度和等级评定程序进行了调整,并建立了相应的准则,对评价对象进行多级综合评价。通过多层次评价,可以获得不同子指标各自的风险等级以及评价对象总体的风险等级。以邯郸市某段燃气管线为例,运用城市燃气管线风险评价模型进行风险评价,得出其多层次风险等级值。通过对比及数据分析,证实了本文方法的可靠性。     

隧道结构地震反应分析研究现状

简要介绍了隧道结构的震害现象,总结了隧道结构的震害机理、震害的影响因素、地震反应计算方法中的反应位移法和隧道结构振动台试验等4个方面的研究进展。在对当前研究成果评述的基础上指出了当前研究中的一些问题,并对隧道结构抗震研究的重点问题进行了总结归纳,包括地震动输入的确定、结构抗震计算方法、特殊地质环境下隧道的动力特性、隧道结构地震破坏的准则与评价指标、隧道结构抗震反应分析模型、振动台试验的可靠性等。这些工作可以为从事这一领域研究和设计工作的有关人员提供一定的参考。     

Influence of subaqueous processes on the construction and accumulation of an aeolian sand sheet

In aeolian sand sheets the interaction between aeolian and subaqueous processes is considered one of the principal factors that controls this depositional environment. To examine the role played by the subaqueous processes on the construction and accumulation of sand sheets, surface deposits and subsurface sedimentary sections of a currently active aeolian sand sheet, located in the Upper Tulum Valley (Argentina), have been examined. On the sand sheet surface, airflows enable the construction of nabkhas, wind‐rippled mantles (flattened accumulations of sand forming wind ripples), megaripples, and small transverse dunes. Subaqueous deposits consist of sandy current ripples covered by muddy laminae. The latter are generated by annual widespread but low‐energy floods that emanate from the nearby mountains in the aftermath of episodes of heavy precipitations. Deposits of subaqueous origin constitute 5% of the accumulated sand sheet thickness. The construction of the sand sheet is controlled by meteorological seasonal changes: the source area, the San Juan river alluvial fan, receives sediment by thaw‐waters in spring–summer; in fall–winter, when the water table lowers in the alluvial fan, the sediment is available for aeolian transport and construction of the sand sheet area. The flood events play an important role in enabling sand sheet accumulation: the muddy laminae serve to protect the underlying deposits from aeolian winnowing. Incipient cement of gypsum on the sand and vegetation cover acts as an additional stabilizing agent that promotes accumulation. Episodic and alternating events of erosion and sedimentation are considered the main reason for the absence of soils and palaeosols. Results from this study have enabled the development of a generic model with which to account for: (i) the influence of contemporaneous subaqueous processes on the construction and accumulation in recent and ancient sand sheets; and (ii) the absence of developed soils in this unstable topographic surface. Copyright © 2013 John Wiley & Sons, Ltd.     

Geophysical Study of Annular Well Seals

Geophysical logging was conducted in 35 in-service water and monitoring wells installed in unconsolidated sediments using a downhole ultrasonic probe to assess how sealant type, construction method, and site geology affect annular seals. Collapsed sand and gravel was frequently detected in the annulus of wells constructed with mud-rotary methods, precluding the placement of sealant and, in some wells, potentially providing a preferential pathway for contamination. High-solids bentonite grout appeared to create high-quality seals when formation materials did not collapse into the annulus. Seals composed of bentonite chips and pellets remained intact when hydrated upon placement; those not hydrated during placement remained dry and porous, posing a risk of surface water infiltration. Seals made with cement-bentonite grout were generally unsaturated and possibly cracked. Analysis of the data suggests that well designers should specify a construction method that minimizes collapse of the formation to ensure that the sealant is placed where intended. When collapse is avoided, high-solids bentonite grout and hydrated bentonite chips and pellets appear to yield intact seals. However, bentonite chips and pellets may not hydrate adequately in the annulus unless hydration water is added during installation. When cement-bentonite grouts are used, the well designer should ensure that the grout will remain intact and plastic after installation.     

永登-古浪高速公路乌鞘岭隧道场地工程地质条件及抗震性能评价

通过对永登-古浪高速公路鸟鞘岭隧道工程场地的地形地貌、地层岩性、水文地质、构造地质、地应力、区域及近场地震活动性等方面进行研究,对场地工程地质条件进行了评价。在此基础上,探索性地对隧道工程的进口、洞身主体和出口进行了抗震性能评价,指出了工程场地不良工程地质现象、地震影响及可能触发的地震灾害效应,为长线隧道工程场地的抗震性能评价工作提供了新的方法及思路。     

橡胶集料风积沙混凝土柱抗震性能试验研究

为研究橡胶集料风积沙混凝土柱的抗震性能,制作了4根相同尺寸的混凝土柱试件,其中包括普通混凝土柱、风积沙混凝土柱、橡胶集料混凝土柱和橡胶集料风积沙混凝土柱。通过低周反复荷载试验,分析各试件的破坏现象、滞回曲线、骨架曲线、刚度退化和延性等抗震性能指标。在试验的基础上,根据能量耗散原理建立累积损伤评价模型,并对结构进行了累积损伤分析。研究结果表明:10%橡胶集料的掺入能够改善混凝土柱的变形能力,但混凝土柱的承载力有所降低;30%风积沙的掺入可以改善混凝土柱的抗震性能;橡胶集料风积沙混凝土柱具有较好的滞回性能,且耗能能力和延性性能明显高于其余试件,柱的抗震性能得到提高;通过累积损伤分析表明:适量掺入橡胶集料和风积沙的可以有效减缓试件的损伤,且该累积损伤模型能够较好的反映出各试件的损伤程度。     

High resolution sensors in space and time for determination saltation and creep intensity

The measurement of aeolian sand transport rates at high temporal and spatial resolution is crucial for further progress in testing and developing numerical models of sand movement by wind and in the modelling of sand dunes, ripples and so on. This paper reports the development and field testing of two sand transport sensors. The first one, a webcam commonly used with personal computers, is a new device in aeolian research. The webcam frame transfer is triggered by a sonic anemometer every 0·1 second. Consecutive frames are compared and analysed in real‐time by a computer program. Changes in pixel light intensity exceeding a threshold level are recorded and interpreted as grain movements. The second sensor is a small‐sized ‘Saltiphone’‐type device made of simple loudspeakers with a diameter of 15 mm as used in MP3 players. It can be deployed as a 2 × 3 array of six such devices distributed to enable horizontal and vertical spatial sampling of the sand flux. The devices are tested under field conditions. Both signals and the sum of microphone impacts over 15 minutes are compared to data gathered using a Guelph sand trap, and very good agreement is found. Measurements in a wind tunnel using sieved natural sand indicate that the webcam can be used to infer additional information about the grain size. As an application, the fluid and impact thresholds for aeolian sand transport are investigated in field measurements by analysing the onset and breakdown of saltation in gust and lull intervals of rising and falling wind speeds, respectively. In this way, constitutive equations for sand transport in terms of the wind speed can be tested. If viable, they can be employed to infer estimates for the thresholds by minimizing the root‐mean‐square error between measured and calculated transport data. Copyright © 2012 John Wiley & Sons, Ltd.     

Modelling aeolian sand transport and morphological development in two beach nourishment areas

The aeolian sand transport model SAFE and the air flow model HILL were applied to evaluate cross‐shore changes at two nourished beaches and adjacent dunes and to identify the response of aeolian sand transport and morphology to several nourishment design parameters and fill characteristics. The main input of the model consisted of data on the sediment, tide and meteorological conditions, and of half‐yearly measured characteristics of topography, vegetation and sand fences. The cross‐shore profiles generated by SAFE–HILL were compared to measured cross‐shore profiles. The patterns of erosion and deposition, and the morphological development corresponded. In general, the rates of aeolian sand transport were overestimated. The impact of parameters that are related to beach nourishment (namely grain size, adaptation length and beach topography) on profile development was evaluated. Grain size affected the aeolian sand transport rate to the foredunes, and therefore the morphology. Adaptation length, which is a measure of the distance over which sediment transport adapts to a new equilibrium condition, affected the topography of the beach in particular. The topography of a beach nourishment had limited impact on both aeolian sand transport rate and morphology. Copyright © 2000 John Wiley & Sons, Ltd.     

复杂长线工程场地工程地质与工程地震条件评价——以永古高速公路为例

本文以甘肃省永登-古浪高速公路为例,通过野外地质调查、物探和钻探工作,对高速公路沿线地形地貌、水文地质、地层岩性介质、构造地质、地震等几个方面进行了详细研究和分类,并在此基础上对公路沿线分段的工程地质与工程地震条件进行了评价,用以说明复杂长线工程场地工程地质与工程地震条件评价的工作内容和方法。研究结果表明永古高速公路沿线工程地质与工程地震条件复杂多变,各区段均有特殊的工程地质问题和工程地震条件,施工设计中应根据各段特点采取相应的措施。     

Ground motion duration effect on responses of hydraulic shallow-buried tunnel under SV-waves excitations

Although intensive research of the influence of ground motion duration on structural cumulative damage has been carried out, the influence of dynamic responses in underground tunnels remains a heated debate. This study attempts to highlight the importance of the ground motion duration effect on hydraulic tunnels subjected to deep-focus earthquakes. In the study, a set of 18 recorded accelerograms with a wide-range of durations were employed. A spectrally equivalent method serves to distinguish the effect of duration from other ground motion features, and then the seismic input model was simulated using SV-wave excitation based on a viscous-spring boundary, which was verified by the time-domain waves analysis method. The nonlinear analysis results demonstrate that the risk of collapse of the hydraulic tunnel is higher under long-duration ground motion than that of short-duration ground motion of the same seismic intensity. In a low intensity earthquake, the ground motion duration has little effect on the damage energy consumption of a hydraulic tunnel lining, but in a high intensity earthquake, dissipation of the damage energy and damage index of concrete shows a nonlinear growth trend accompanied by the increase of ground motion duration, which has a great influence on the deformation and stress of hydraulic tunnels, and correlation analysis shows that the correlation coefficient is greater than 0.8. Therefore, the duration of ground motion should be taken into consideration except for its intensity and frequency content in the design of hydraulic tunnel, and evaluation of seismic risk.