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1.
Chungsik Yoo 《Marine Georesources & Geotechnology》2017,35(3):305-317
This paper presents the results of an investigation into the effect of lining leakage on the structural performance of lining in subsea tunnels. A parametric study on a number of hypothetical subsea tunnels was conducted within the framework of two-dimensional stress–pore pressure coupled finite element analysis with due consideration of tunnel cover depth, depth of water to seabed, and ground type. The results indicate that the lining leakage increases axial thrust as well as bending moment, with more pronounced increases in bending moment. Also shown is that there exists an increasing trend of leakage induced lining forces with an increase in the water depth above the seabed but with no significant influence from the cover depth. It is also shown that the progressive development of leakage induced lining forces can be best fitted with an exponential function which can be used to predict the lining force increase for a given tunnel condition. Practical implications of the findings are discussed. 相似文献
2.
针对采用定值相对极限位移判定隧道围岩稳定性时存在的问题,提出了采用模糊概率理论判定隧道围岩稳定的计算方法.结合厦门翔安海底隧道工程实际,利用曲线回归和模糊概率方法对海底隧道围岩稳定性概率进行了计算分析.参考现行规范并根据海底隧道各个开挖步的变形量综合确定极限相对位移上下限,采用指数函数对海底隧道CRD1部和CRD3部的拱顶下沉收敛曲线进行了回归分析.根据回归参数及实测结果,应用模糊概率公式对隧道围岩的稳定性概率进行了计算,从而为根据某个时刻的相对位移来判断海底隧道稳定性提供了参考. 相似文献
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由于海底隧道的特殊性，其防排水技术与一般陆地隧道有着显著区别，本文介绍了厦门翔安海底隧道的防排水方案设计情况，对方案实施效果进行了评估．得出了海底隧道防排水应结合围岩与支护的自防水功能采取以堵为主的原则，并针对海底隧道防排水方案实施中的问题，提出了对初期支护背后注浆是重点，改进注浆材料等建议．从而论述了防排水技术是海底隧道工程建设的核心问题． 相似文献
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Tingjin Liu Honghao Huang Zhenrui Yan Xinwei Tang Hongyuan Liu 《Marine Georesources & Geotechnology》2020,38(7):786-803
AbstractThe Zhanjiang Bay Sea-crossing Tunnel is the first phase of an ambitious plan of the Golden Triangle Economic Zone in southwestern China and passes underneath the deepest artificial shipping channel with the highest level in Asia. The tunnel is a world-record extralong and small-diameter corridor constructed using an uninterrupted single-end shield tunneling method in subsea soft ground under ultrahigh hydraulic pressure for water conveyance. This case study first highlights the engineering challenges of constructing the sea-crossing shield tunnel in subsea soft ground under ultrahigh hydraulic pressure. A series of key techniques are then investigated and some innovations are proposed to address the engineering challenges in the following four key aspects of the sea-crossing shield tunneling process: (a) optimal design of segmental linings; (b) adaptive reformation of the shield machine; (c) structural construction of deep vertical shafts; and (d) supporting techniques of long-distance advancing. On the basis of the field monitoring and numerical analyses, it is concluded that the implemented key techniques ensure the successful management and control of the engineering challenges in terms of optimizing the segmental lining, selecting the shield machine and constructing the vertical working shaft during the sea-crossing shield tunneling process with limited geological investigation data available under submarine conditions. 相似文献
5.
The presence of a fractured zone at a tunnel face can threaten the stability of the tunnel by causing water leakage and degradation of the soil strength. In this case, to stabilize the tunnel face, the pore water pressure is generally reduced and the loss of soil particles is prevented by installing drainpipes. The installation of drainpipes, however, can cause the concentration of flow channels and other ground instability problems. In this paper, a novel pin-holed pipe anchor is proposed to overcome the problems occurring in subsea tunnels. The pin-holed pipe anchor is a pipe-type support member designed to reinforce the ground while simultaneously enabling flow into the tunnel. Here, the design requirements of the pin-holed pipe anchor were examined through material tests, and the structural–hydraulic characteristics of the pin-holed pipe anchor were investigated through a model test. Furthermore, the applicability of the pin-holed pipe anchor to an actual tunnel was evaluated by numerical analysis of actual tunnels. Through selection of an appropriate perforated drainage area and bonded length, the pin-holed pipe anchor contributed to the improvement of the structural and hydraulic stabilities of the tunnel. 相似文献
6.
This study used the strength reduction method to analyze the seismic stability of a subsea tunnel under the effects of seepage and temperature. Excess pore water pressure within the rock mass was first eliminated by calculating the consolidation; then, an earthquake wave was applied to begin the dynamic and time-history analysis and to obtain the maximum horizontal displacement of the model boundary. Finally, a temperature field model was established for the thermal analysis of the structure. The temperature of each node of the structure was regarded as a form of outside load applied to the reduction model; both sides of the vertical horizontal displacement of the boundary nodes and gravity were used as inputs for the static analysis when the vertex horizontal displacement reached its maximum value. By continuously decreasing the shear strength parameters, the safety factor of the tunnel structure was determined. The results show that the plastic zone first appeared in a smaller range on both sides of the tunnel arch feet near the lining and vault of both sides. The safety factor decreased with increasing water depth and overburden layer thickness. 相似文献
7.
Yiguo Xue Zhiqiang Li Shucai Li Daohong Qiu Maoxin Su Zhenhao Xu 《Marine Georesources & Geotechnology》2013,31(7):816-827
AbstractThe geological conditions of subsea tunnels are extremely complex, and a water inrush disaster is prone to occur when crossing a fault. Based on a geological analysis using cloud theory, analytic hierarchy process (AHP), and entropy weight theory, we aim to establish a normal cloud model with combination weight for water inrush risk evaluation in subsea tunnels. We select seven main factors, namely, the surrounding rock grade, rock integrity, overburden thickness, seawater thickness, tunnel section, permeability coefficient, and construction technology level as risk assessment indicators for the evaluation model. The risk is divided into five levels, and the numerical characters of the cloud model are calculated based on the standard of each risk level. The subjective weight and the objective weight are determined using AHP and the entropy weight method. The combination weight is calculated using the Delphi method. The comprehensive certainty degree is used to determine the risk level of water inrush. The model is applied to the Qingdao subsea tunnel to evaluate the water inrush risk crossing the F4-1 fault, and the results are basically consistent with the actual excavation conditions. This article provides a new idea for the risk assessment of water inrush in the subsea tunnel. 相似文献
8.
Analyses of Seepage Problems in a Subsea Tunnel Considering Effects of Grouting and Lining Structure
Guangcheng Yang Xinghua Wang Xiangge Wang Yonggang Cao 《Marine Georesources & Geotechnology》2016,34(1):65-70
Analytical solutions for water inflow and water pressure based on steady-state water inflow into a circular subsea tunnel in a semi-infinite aquifer are deduced depending on the rock permeability, drainage at the lining, and grouting parameters. Based on the parameters of the Qingdao Jiaozhou Bay subsea tunnel, the differences between the proposed solutions and three previous methods are analyzed. Comparisons of the results of different methods verify the validity of the proposed analytical solutions and manifest the superiorities of the proposed solutions in reflecting the effects of grouting and lining structure on the seepage problems in a subsea tunnel. Discussion of the lining structure is also made and we conclude that “block-based and limited drainage” should be the design principle of lining structures. Finally, the method of identifying the most rational and economical grouting parameters is presented. 相似文献
9.
Maoxin Su Peng Wang Daohong Qiu Zhiqiang Li Teng Xia 《Marine Georesources & Geotechnology》2013,31(9):1119-1129
AbstractCollapse is a major threat in tunnel construction. How to predict collapse risk accurately and timely is a complicated problem. In this paper, a non-linear mathematical model is applied to obtain the potential risk indices for a submarine tunnel using statistical analysis based on previous submarine tunnels, such as the Seikan tunnel and Xiang’an tunnel. Rough set theory is used to screen risk indices, determine each indicator value, and classify risk factors. Traditional weight calculation methods that are overly dependent on expert experience and other subjective factors are optimized and improved. Based on the frequency of each risk factor, the objective weight value of each risk index is determined according to weight back analysis theory. The ideal point method is used to calculate the collapse risk level. Predictions made by this new method are consistent with the actual tunnel collapse risk levels. This new method provides theoretical and technical basis for effectively predicting tunnel collapse. 相似文献
10.
Shu-Guang Song Shu-Cai Li Li-Ping Li Qian-Qing Zhang Kai Wang Yi Zhou 《Marine Georesources & Geotechnology》2016,34(4):376-383
During tunnel excavation, the deformation of surrounding rock due to the unloading of rock mass will vary with time. However, the measured displacement of surrounding rock is only a part of the actual longitudinal deformation profile. There is a need to analyze the longitudinal deformation profile to identify the deformation state and evaluate the stability of surrounding rock mass. In the present article, the variation of pre-deformation of surrounding rock due to excavation was analyzed, and the release coefficient was obtained from the measured results. For the Qingdao subsea tunnel, the measured crown settlement of surrounding rock was analyzed using the regression analysis method, and the longitudinal deformation profile of rock mass was simulated using the numerical calculation method. Moreover, based on the conditions of the subsea tunnel, a solid-fluid coupling model test was carried out to check the reliability of the numerical calculation results. The results of the model test were consistent with the numerical calculation results. 相似文献
11.
将衬砌分别视为多孔柔性材料和弹性介质,在频率域内研究内水压力作用下饱和分数导数黏弹性土-深埋圆形隧洞多孔柔性或弹性衬砌系统的耦合简谐振动。土体的宏观力学特性采用多孔介质理论来模拟。通过引入与土体体积分数相关的应力系数,利用衬砌和土体界面处位移连续,分别得到饱和黏弹性土和衬砌的位移、应力和孔隙水压力等的解析表达式。在此基础上,分析了多孔柔性衬砌和弹性衬砌结构的差异,并考察了应力系数、渗透系数、分数阶导数本构参数等对系统动力响应的影响,结果表明:多孔柔性衬砌材料条件下系统的动力响应明显大于弹性衬砌材料条件下系统的动力响应;随着分数导数阶数和材料参数比的增加,系统共振效应明显减弱;衬砌边界透水和不透水只是反映边界渗透性的两种极限状态。 相似文献
12.
Yiguo Xue Binghua Zhou Daohong Qiu Maoxin Su Chuanqi Qu Xueliang Zhang 《Marine Georesources & Geotechnology》2013,31(10):1267-1276
AbstractThe overlying rock thickness of a subsea tunnel controls its vertical line. It not only ensures the safety and stability of tunnel construction period and operation period, but also ensures the economy of subsea tunnel. In the current research, few papers give full consideration to the complex indicators of prediction the overlying rock thickness. However, in this study, a hybrid intelligent system was established to predict the overlying rock thickness of a subsea tunnel based on Qingdao Kiaochow Bay Subsea Tunnel, China. The sea depth, basic quality index of rock mass, soft soil layer thickness, permeability coefficient, and construction management level were selected as the main factors influencing the overlying rock thickness. Using the data obtained from project site exploration, objective weight factors were calculated using rough set theory, and subjective weight factors were calculated using the analytic hierarchy process. Furthermore, the combination of weights was obtained for each factor. Finally, the weight of influencing factors was incorporated into the extension model, and the overlying rock thickness of pending section was calculated. The results of overlying rock thickness prediction model are consistent with the actual value, indicating that the model has good engineering applicability and application value. 相似文献
13.
以上海复兴东路大型越江盾构隧道为工程背景。通过建立适合工程结构及工程地质特点的弹性地基模型,在充分考虑隧道结构荷载作用特点、地下水的影响及隧道下部土体反力特性的基础上,推导出了隧道纵向位移的解析表达式,并采用基于土体反力系数的迭代解析方法,计算了部分南线隧道各管片纵向位移值,所得结果与实测结果基本吻合。 相似文献
14.
隧道技术是IPv6协议的1个组成部分,按照底层的承载协议不同,分为IPv4隧道和IPv6隧道。文中描述了未来将广泛应用的IPv6隧道的原理,目前各种主流网络操作系统对IPv6隧道的支持情况,提出如何在CERNET2高速网络上利用IPv6隧道来传输IPv4流量。 相似文献
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The long-term settlement of a subway tunnel, especially the differential settlement affects the safe operation of the subway. In this article, the settlement of a subway tunnel was studied from the theoretical and numerical analyses based on the monitoring data. According to the monitoring data, the deformation of segments at different locations is different, and the deformation around a channel is larger than other places. The settlements of tunnel calculated by two theoretical methods are consistent with that obtained in the centrifuge model test. The numerical simulation indicates that the vertical displacement is much bigger than the horizontal displacement. 相似文献
17.
A new study investigates an unburied offshore “snaked” pipeline behavior under various types of seismic faults. The snaking of the pipeline is caused by the thermal/pressure expansion and soil friction. The snaking takes place at a certain distance from the pipeline's unrestrained end and gradually increases towards the restraint. It is shown that longitudinal seismic faults have less effect on a straight pipeline than a snaked pipeline. The new seismic analysis demonstrates that an increase of ground displacement causes a very small change in bending and longitudinal stresses. The new approach results in a safe, subsea pipeline construction and operation with a significant cost reduction. 相似文献
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地下气库的围岩稳定性关系到地下气库的安全与使用。影响地下洞室稳定的因素很多,解析法虽然可以得到精确解,但是只能针对圆形洞室。而数值计算方法可以计算各种情况下围岩的应力、变形、塑性分布等情况。利用有限元分析软件分析了洞室形状对围岩稳定性的影响,确定了合理的洞形;讨论了围岩应力应变随深度的变化规律,以及不同的支护类型对围岩变形的影响,确定了经济合理的支护类型。最终为该地质条件下的洞室围岩稳定设计提供了依据。 相似文献
20.
Various monitoring systems have been applied to warn regarding debris flow; however, the information regarding the selection sensors and determination of the installation area is deficient. The objective of this paper is to propose an appropriate monitoring system to prevent debris flow and a method for determining the installation location. A web-based database is used to find the applied frequency of sensors, and the sensors are grouped into eight parts with consideration of the performance, including rainfall, debris flow velocity, displacement, fluid pore pressure, ground vibration, image processing, impact force, and peak flow depth. Through the statistical technique, the rain gage and geophone sensors are revealed as hugely selected sensors among various systems to provide an alarm. The analytic hierarchical process (AHP) is also used to analyze experts’ opinion through pairwise comparison with consideration of eight geotechnical parameters, including the fine content, void ratio, shear strength, elastic modulus, hydraulic conductivity, saturation, soil thickness, and water content. The weighting factors of every parameter are deduced through AHP and the installation area is chosen with calculated values using the weighting factor. The suggested analyses are helpful to select appropriate sensors and determine the installation location of a monitoring system. 相似文献