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随着地铁网络不断完善,越来越多的新建盾构隧道近距离穿越既有隧道,然而对于盾构隧道近距离穿越既有隧道影响的研究尚不够完善。以上海典型软弱地层为背景,通过离心模型试验,研究了不同注浆率下的盾构上穿越施工对既有隧道以及周围地层的影响。选用排液法在离心场中模拟盾构施工,在不停机状态下成功模拟隧道开挖卸载、地层损失和注浆效应。分析了在不同的注浆率条件下,既有隧道在上穿越施工期和工后长期的位移、周围孔压和纵向应力的变化规律。试验结果表明,新建隧道近距离上穿越既有隧道时,隧道开挖的卸载效应等会导致既有隧道的隆起,但随着注浆率增大,既有隧道的隆起量减小。但过高注浆率对周围土体扰动较大,从而导致工后既有隧道的沉降也越大。 相似文献
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盾构隧道施工中采用了特殊的工艺——壁后注浆,包裹了隧道表面预埋设的土压力计,壁后注浆对土压力计的包裹将影响其监测结果的可靠性。在注浆体力学试验基础上,建立能考虑注浆体固结硬化过程的有限元模型,探讨注浆体层的包裹对土压力计监测结果的影响。注浆体注入盾尾空隙后,终凝前处于流动状态,具有较强调节土压力计部位局部土体不均匀沉降和畸变应力场的能力,监测土压力与实际较为接近,其匹配误差远小于通常地下结构表面监测土压力的匹配误差。 相似文献
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盾构法施工过程的有限元模拟 总被引：3，自引：0，他引：3
在综合考虑了现有的有限元模拟方法的基础上,对部分仿真模拟细节进行了改进,改进了水平荷载的施加方法,用"等代层"来模拟盾尾建筑空隙,用预设单元的刚度迁移来模拟盾构的推进过程。通过对某地铁隧道盾构施工过程的模拟,分析了盾构推进过程中地表土体的位移与变形,计算得到的隧道横断面和隧道纵向地面沉降分布曲线与实测数据比较接近,结果证明了模拟方法是可行的。 相似文献
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Elisabetta Cattoni Chiara Miriano Laura Boco Claudio Tamagnini 《Acta Geotechnica》2016,11(6):1385-1399
In this work, the effects of coupled hydromechanical (consolidation) processes associated with shield tunneling excavation in soft clays are investigated with particular attention to the prediction of ground movements at the ground surface. A series of 2d FE analyses have been carried out in parametric form in order to investigate the effects of tunnel excavation velocity relative to the soil consolidation rate and the hydraulic boundary conditions at the tunnel boundary. The shield advancement process has been simulated with a simplified procedure incorporating both volume loss and ovalization of the tunnel section. In order to investigate the relative importance of soil consolidation during the excavation process, different characteristic times for the tunnel face advancement and for the consolidation process around the tunnel have been considered, for the two limiting conditions of fully permeable liner and impervious liner. The potential damage induced by the tunnel excavation on existing structures, based on computed ground surface distortions and horizontal deformations, has been found to vary significantly with time during the consolidation process. The results of the simulations allowed to obtain useful information on the minimum tunnel face advancement speed for which the assumption of fully undrained conditions for the soil during the excavations is acceptable, as well as on the speed range for which solving the fully coupled hydromechanical problem is necessary. 相似文献
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基于混合物理论孔隙-裂隙岩体的双重孔隙介质水力耦合计算的微分方程,利用伽辽金有限元法提出了相应的有限元公式,并基于岩体分类指标（RQD,RMR）提出了与岩体应变状态相关的渗透系数计算公式。编制了裂隙岩体双重介质流固耦合的2-D有限元程序,给出的验证算例表明,该程序是合理和实用的。同时将该程序用于隧道开挖的模拟计算,探讨渗流效应对开挖隧道围岩变形与渗流场的影响。计算结果表明,在隧道设计中不考虑渗流的影响是偏于不安全的。 相似文献
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Supot Teachavorasinskun 《Geomechanics and Geoengineering》2018,13(3):226-232
Tail void grouting initially does facilitate the action of ground loads around the lower half of the liner and no excess pressure being accumulated. However, at a later stage (almost at the completion of grouting), grout pressure becomes non-uniformly distributed around grout injection holes especially on the upper half of the liner. In the present study, the boundary and loading conditions were simulated by using a series of finite element analyses. It aimed to explore the effects of such temporary non-uniform loading conditions on development of the liner internal forces. The results obtained for tunnel with diameter of 6.0 m were presented. It was found that there were critical locations where application of non-uniform grouting pressure could result in large amounts of bending moment and deformation. Those critical locations; about ±30° to ±50° from crown of the tunnel, were about the locations where actual grouting was injected in the field. The stiffness of sub-soil beneath the tunnel invert had minor effect on the amount of induced structural forces. However, ground coverage was more important. The results, though cannot fully represent complicated tail grouting behaviours, provided a simple analytical procedure for exploring the effects of tail void grouting on the segmental liner. 相似文献
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浅埋偏压隧道洞口坍方数值分析与处治 总被引：2，自引：0，他引：2
某公路隧道在进洞时出现坍方。针对该隧道工程的实际情况,建立数值分析模型,采用ANSYS程序模拟隧道施工力学行为,从围岩塑性区分布、位移以及锚杆和混凝土衬砌内力分布情况分析隧道变形和坍塌发生的原因。结果表明：隧道浅埋偏压、围岩力学性质差及施工支护不当导致坍方。结合工程实际提出洞内加固、地表注浆加固及开挖控制的综合处治方法,取得了理想的效果,为日后类似工程提供借鉴与参考。 相似文献
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盾构隧道壁后注浆扩散模式及对管片的压力分析 总被引：12，自引：2，他引：10
在假定注浆浆液为牛顿流体,并在盾尾间隙影响厚度范围内均匀柱面扩散的前提下,通过引入等效孔隙率替代土体本身的孔隙率来考虑建筑间隙的影响,对盾尾注浆和管片注浆2种情况下的浆液渗透范围及因注浆而对管片造成的压力进行了理论推导,得到了浆液扩散半径及对管片产生的压力计算式。结果表明,盾构隧道壁后注浆浆液的扩散半径及对管片产生的压力与注浆压力、注浆时间、土体特性及浆液性质等众多因素有关,盾尾注浆对管片产生的注浆压力小于管片注浆对管片产生的压力。在假定其他参数已知的条件下,通过一具体实例,讨论了盾尾注浆时浆液扩散半径及注浆对管片产生的压力与注浆压力及注浆时间的关系。结果显示,虽然增大注浆压力、延长注浆时间均能增大浆液的扩散半径及对管片产生的压力,但增长速度不尽相同。 相似文献
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This paper examines the effect of the stress disturbance induced by tunnel construction on the completed tunnel’s seismic response. The convergence-confinement method is used to simulate the tunnel construction prior to the dynamic analysis. The analysis is performed using the finite element method and drained soil behaviour is simulated with an advanced multi-mechanism elastoplastic model, utilising parameters derived from laboratory testing of Toyoura sand. The response of the soil and of the lining during dynamic loading is studied. It is shown that stress disturbance due to tunnel construction may significantly increase lining forces induced by earthquake loading, and Wang’s elastic solution appears to underestimate the increase. 相似文献
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劈裂注浆抬升既有管道效果分析及工程应用 总被引：1，自引：0，他引：1
地铁车站施工中常穿越大量的市政管道,由于隧道开挖引起地层损失和地表沉降,地下管道将会发生变形,往往影响地铁施工,注浆是对地下管道进行沉降控制的主要技术措施。以北京地铁黄庄站下穿热力管道抬升注浆工程为研究对象,利用三维有限差分数值方法分析了新建车站开挖引起超大管道的变形特征。结果表明,在抬升区注浆单元施加膨胀压力可以较好模拟注浆抬升既有管道的效果;采用应变软化模型,可以有效模拟土体材料的弹塑性力学行为,反映注浆完成后浆脉的固结和周围土体的湿陷作用。对比注浆抬升模拟计算和沉降监测结果,验证了有限差分数值方法模拟劈裂注浆抬升管道过程的正确性和有效性。同时模拟分析注浆抬升管道的影响因素,获得了一些规律性的认识,为劈裂注浆抬升地下管道工程的施工和设计提供指导。 相似文献
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采用非饱和的渗流应力耦合模型分析了糯扎渡水电站2#导流洞的开挖过程,导流洞部分洞身穿过节理带,洞顶水头较高。详细地讨论了高水头和节理带对施工过程的影响。节理带采用描述高密度平行节理组的各向异性节理本构来逼近;考虑开挖引起的介质变形对渗透系数的影响;考虑排水引起的饱和度变化对渗透系数的影响。所用的非饱和瞬态耦合模型可以模拟出开挖引起的EDZ区域孔隙水压力急剧升高、有效应力减小、渗透系数动态的变化以及排水对洞室稳定性的提高。数值模拟的计算结果与国外类似试验的一般性观测结论相吻合,因此,可以用来评价水位以下隧洞施工方法和施工速度的合理性和经济性。 相似文献
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《Computers and Geotechnics》2006,33(4-5):234-247
For shield-driven tunnels, the influence of the soil and grout material properties and of the cover depth on the surface settlements, the loading and deformation of the tunnel lining and the steering of the TBM is investigated numerically. To this end, comparative numerical simulations of a mechanised tunnel advance in homogeneous, overconsolidated, soft, cohesive soil below the ground water table are performed and sensitivities are evaluated. The advancement of the step-by-step tunnel construction process is modelled using a three-dimensional finite element model, which takes into account all relevant components of shield tunnelling. The material behaviour of the saturated soil and the tail void grout is modelled by a two-field finite element formulation in conjunction with an elasto-plastic Cam-Clay model for the soil and a hydration-dependent constitutive model for the grout. The analyses provide valuable information with regard to the significance of the investigated parameters and demonstrate the complexity of the various interactions in shield tunnelling. 相似文献
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Liu Yang Feng Yongneng Xu Mo Zhang Yunhui Long Haitao Zhu Haiming 《Natural Hazards》2019,98(2):343-377
Tunnel water inrush disaster is a serious problem in karst tunnel construction and occurs extensively in southwestern China. To prevent water inrush, hydraulic lining has been utilized extensively in karst tunnel construction. The failure of the hydraulic lining in the Tongxi tunnel is an example of a typical failure case that has yet to be fully analyzed. In this paper, the failure of the waterproof liner was studied by theoretical and numerical methods. By field investigation, the failure of the tunnel lining was attributed to a high hydraulic pressure head converging in the large karst caves behind the lining. The corresponding mechanical model can be simplified as a “karst cave water pressure” model. The key to the mechanical model was to determine the water pressure of the karst caves produced by the lining. The variation in water pressure was directly related to the cave’ reservoir volume, catchment flow and catchment time. Thus, volume calculation formulas for two types of karst caves (strike and oblique caves) in the studied tunnel were constructed based on the engineering geological conditions. Considering the precipitation, the flow rate in the karst caves was regarded as nearly constant during the catchment period. Hence, reservoir volumes during different periods can be calculated and converted to the stress boundary conditions of the lining. Then, the mechanical response of the tunnel under different water levels was calculated by numerical simulation. Combining the field investigation and monitoring data, the tunnel lining failure was mainly believed to be triggered by hydraulic fracturing failure due to a high-pressure head. Finally, prevention measures were proposed based on the results of this study.
相似文献16.
盾构隧道实测土压力分布规律及影响因素研究 总被引：1，自引：0，他引：1
以大量现场实测土压力为基础,分析了影响盾构隧道衬砌土压力的一些主要因素,总结出不同地层地铁盾构隧道长期稳定土压力的分布规律,并探讨了盾构施工期土压力随时空的变化情况。研究得出,地下水位高低对稳定土压力大小及分布影响较大;作用在管片上的长期土压力大小与地层衬砌刚度系数有关,当地层衬砌刚度系数为1.5时,管片竖向及水平土压力都较小;盾构施工期临时荷载对管片土压力影响不可忽视,无论是黏土地层还是砂土地层,大的注浆压力及注浆率将导致作用在管片上的稳定土压力分布不均;管片土压力可按时空分为4个阶段,拼装阶段、同步注浆阶段、浆液凝固阶段及后期稳定阶段,其中同步注浆阶段管片周边最大土压力为稳定阶段的2～3倍。 相似文献
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盾构隧道施工土体扰动范围研究 总被引：1，自引：0，他引：1
盾构隧道施工,隧道周边土体应力场发生改变,临近隧道土体因应力扰动出现塑性区,塑性区的分布范围与注浆压力、注浆量等注浆参数密切相关。塑性区被认为是施工扰动比较严重的区域,为分析盾构施工扰动范围,基于小孔扩张理论研究了注浆压力、注浆量对土体扰动塑性区的影响,推导了塑性区与注浆压力和注浆量之间的函数关系。在定义扰动评价标准基础上,提出应用有限元计算盾构施工塑性区和扰动范围的一种简捷实用的数值方法。最后采用静力触探现场测试盾构施工扰动范围,并与理论公式及有限元方法进行比较,理论公式、有限元及现场测试三者取得了较为一致的结果,验证了推荐方法的有效性。其研究结果可对盾构施工注浆参数的正确选择提供理论支持。 相似文献
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在城市地铁盾构施工过程中,地表沉降是重要的工程问题之一,不但影响地铁隧道的安全建设,更直接关系到周边紧临建筑物的正常运营。等代层压缩模量是控制地表沉降的关键参数,特别是软弱土层中的地铁盾构。等代层注浆材料与土体的混合比例关系、注浆后的养护时间是直接影响其压缩模量的重要因素。本文依托昆明地铁3号线石咀段泥炭质土层盾构工程,进行注浆材料与泥炭质土的不同比例关系及不同养护时间条件下的压缩模量试验研究。探索泥炭质土层中盾构等代层中浆体与土体的合理比例关系,并提出注浆后何时能达到预期的等代层压缩模量,为泥炭质土地区地铁盾构施工提供参考。 相似文献
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It has been widely accepted that reinforcement made of polyethylene and polypropylene is susceptible to creep and soil’s hydraulic conductivity varies with its void ratio. However, unfortunately there is no available sensitivity analysis on time-dependent embankment behaviour taking either reinforcement viscosity or time varying hydraulic conductivity of subsoil into consideration. The influence of geosynthetic reinforcement viscosity and decreasing hydraulic conductivity with consolidation on the time-dependent performance of embankments with floating columns is investigated using a fully 3D coupled model. For an embankment at the working height corresponding to a post-consolidation polypropylene geotextile strain of about 5%, it is shown that the assumption of constant hydraulic conductivity and the failure to consider the viscous behaviour of geosynthetic reinforcement can underestimate time-dependent embankment deformations (including differential crest settlement and horizontal toe movement). The effects of factors including the foundation soil, reinforcement stiffness, column stiffness, column spacing, column type (floating and fully penetrating), and construction rate, on the time-dependent behaviour of column supported embankments are explored. 相似文献
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《Computers and Geotechnics》2006,33(6-7):316-329
The aim of the paper is to provide new elements concerning the constitutive behavior of sedimentary rocks and the numerical aspects for basin simulators. A comprehensive model for mechanical compaction of sedimentary basins is developed within finite poroplasticity setting. Particular concern is paid to the effects of large porosity changes on the poromechanical properties of the sediment material. A simplified micromechanics-based approach is used to account for the stiffness increase and hardening induced by large plastic strains.A key challenge for numerical assessment of sedimentary basin evolution is to integrate multiple coupled processes in the context of open material systems. To this end, a numerical approach inspired from the ‘deactivation/reactivation’ method used for the simulation of excavation process and lining placement in tunnel engineering, has been developed. Periods of sediments accretion are simulated by progressive activation of the gravity forces within a fictitious closed system. Fundamental components of the constitutive model developed before (hydromechanical coupling, dependence of poroelastic properties on large plasticity, impact of irreversible porosity changes on the hardening rule, evolution of permeability with porosity) are included into our finite element code.Illustrative examples of basin simulation are performed in the one-dimensional case. Various aspects of the constitutive model are investigated. Their influence on the corresponding basin response is analyzed in terms of compaction law, porosity and fluid pressure profiles. 相似文献