Rehabilitation project of the Dabanshan highland road tunnel

The rehabilitation project of road tunnel in highland area and cold region is an important and worthy exploring research field. The development of the defects of crack in the liner, water leakage, structural deterioration and frost defects for Dabanshan road tunnel are studied. After an insight into the cause and development of tunnel defects, the water leakage and frost damage are considered as the root of defect, so restoration of drainage system and the reinstallation of cold prevention system are the focuses of the rehabilitation project. For consideration of safety, cover arch is installed for the tunnel structure enforcement as well. Results indicate measures in Dabanshan road tunnel rehabilitation project are effective for road tunnel of high altitude and tunnel in cold region.     

Explosion dynamic response of soil surrounding tunnel with curve wall

It’s significant to obtain the mechanic laws and weak parts of soil tunnel, and the most likely failure elements under the explosion shock action to prevent terrorist attacks which can cause tremendous loss of human life and property and collapse and damage of many buildings and construction. Therefore, numerical simulation for soil tunnels is carried through the explicit dynamic finite element program ANSYS/LS-DYNA, and the time-history curves are discussed about the soil surrounding tunnel under explosion action. The dynamic response of soil tunnel under the explosion action is analyzed by establishing finite element integral model of soil tunnel dynamic analysis and comprehensively considering the solving method of nonlinear dynamic equation, the selection of different material models, the method of explosion shock wave input and the convergence and realizing factors of fluid-solid coupling effect. Thus, a reference for antiknock design of tunnels is presented.     

Influence on new tunnel mechanics behaviorinduced by construction about adjacent spacing

This paper takes Chongqing Two-River Tunnel as the research background, based on the system for structure and surrounding rockmass of the highway tunnel, conducts a three-dimension model test about forked tunnel with different altitude to study new tunnel’s mechanics behavior induced by construction, and uses numerical simulation to analyze model domain. The results show that the displacement on new tunnel’s left hance is larger than the displacement on its right hance. Left hance displacement is larger than hance displacement of the single tunnel, and the right hance displacement is less than hance displacement of the single tunnel. The trend of hance displacement and crown settlement with different adjacent spacing is got. Normalizing hance displacement and crown settlement of model test, the relation between displacement and adjacent spacing is disclosed. The hance displacement and crown settlement gained by numerical simulation is close to the converted result of model test, which indicates that the model test data is consistent with the result of numerical simulation.     

实测确定公路隧道洞外景物亮度的方法

分析比较了查表法、环境简图法和黑度法3种确定洞外亮度的方法,发现3种方法均未完全考虑隧道所处区域的环境和光气候条件。为了能快速准确地确定隧道洞外景物亮度,以从莞高速公路的7座隧道为测量对象,通过现场实测,建立了洞外景物亮度与水平面照度之间的关系。在对当地光气候数据进行统计分析的基础上,确定隧道洞外景物亮度标准值、东莞地区隧道洞外典型景物亮度设计参考值,并得到了东莞地区4个朝向隧道洞外典型景物亮度值。     

Theoretical calculation and monitoring on rock pressure of shallow-buried bilateral bias neighborhood tunnel

In order to research the tunnel rock pressure and its distribution, the mechanical model of tunnel rock pressure of shallow-buried bilateral bias neighborhood tunnel is set up based on series assumptions. The calculation theory of tunnel rock pressure is deduced, in which the construction processes of twin tunnels can be considered. Furthermore, the contact pressure between tunnel lining and surrounding rock is monitored on site at Zuan Qianmen Tunnel of Xinbao expressway, and the change law of contact pressure corresponding with time and construction processes is obtained. Meanwhile, the comparison analysis has been made between field monitoring value and theoretical value, and the result shows that the tunnel rock pressure’s mechanical model and calculation theory of shallow-buried bilateral bias neighborhood tunnel is rational, which will provides the theory foundation to tunnel design and tunnel rock pressure calculation of shallow-buried bilateral bias neighborhood tunnel.     

An expert system for diagnosing fire-caused damages to reinforced-concrete tunnel lining

During the last four decades, reinforced-concrete structure failures have been happening widely for many reasons, such as increased service loads, war accidents, fire, and durability problems. The economic losses due to those failures are very high. An expert system is an interactive computer-based decision tool that uses both facts and heuristics to solve difficult problems based on knowledge acquired from experts. To realize these requirements, a logic programming visual basic language is used together with visual diagnosis. The expert system, Diagnosis of Fire-Caused Damages to Reinforced-Concrete Tunnel Lining (DFCDRCTL) was developed in this work for diagnosing the annual damages caused by fire. The program is used as an alternative of a human expert to make annual technical decisions in diagnosing fire damages at the second reinforced-concrete tunnel lining segment. It is concluded that the proposed DFCDRCTL expert system is easy to use, and is fast and helpful for engineers.     

Analysis of comprehensive evaluation method on safety of mountain tunnel initial support

Through collecting and collating information of 62 tunnels with initial support fracture,the risk grade is summed up,the factors causing initial support fracture are divided into two types：objective factors and subjective factors. The statistical results show that the proportion of controlled subjective factors’ reached as large as 25%. The comprehensive evaluation model on safety of mountain tunnel initial support by analytic hierarchy process (AHP)and fuzzy comprehensive evaluation is established. On this basis,the science rational risk response method is required. Then the evaluation model is proved credible by field measurements.     

Rock classification method for tunnel boring machine

In order to study the geological factors which impact penetrating rate of tunnel boring machine (TBM), this paper uses three-dimensional discrete element model 3DEC to build simulated models on rock fragment by TBM cutter. It analyzes the influence of different geological conditions on TBM penetrating rate and classified the surrounding rock in west route of south-to-north transfer project according to the drill ability of TBM in surrounding rock. The results show that the penetrating rate of TBM is closely related to the mechanical properties of rock and joint conditions in rock mass. In certain extent, TBM penetrating rate will be increased with the decrease of rock strength or closely distributed joints. TBM penetrating rate will be decreased with the increase of rock strength or rarely distributed joint. Another result is that the surrounding rock by TBM penetrating can be divided into three classes based on the drill ability of TBM in surrounding rock, which can guide the TBM penetrating.     

Analysis on the influence from rectangle cavity behind the lining to the primary support of tunnel

In process of the tunnel construction throw New Austrian Tunnelling Method, the result of smoothwall blasting to rock tunnel is not good, there are more and more cavities produced behind the lining. On the basis of engineering project, this paper makes the three-dimensional elastic-plastic analysis throw numerical simulation, discusses the stress-strain behavior of primary support when there is a different size of rectangle cavity behind the lining. In addition the safety factor of tunnel is calculated with cavity based on the strength reduction finit element method. This factor is compared with the factor of health tunnel. The stability of tunnel structure system is estimated through the linear regression analysis between stress of lining and safety factor.     

Stability analysis on shallow tunnel with floor lift under inclined ground by upper bound method

采用极限分析上限法,基于内外能耗守恒原理,通过构建考虑隧底隆起的斜坡地段浅埋隧道破坏模式,推导出围岩压力的计算式,并通过典型算例重点分析了典型因素对隧道围岩稳定性的影响。研究结果表明：基于泰沙基极限平衡法进行隧道围岩支护设计较为保守,不考虑隧底隆起的极限分析方法次之考虑隧底隆起极限分析方法的风险最大;斜坡地表倾角增大对浅埋隧道稳定性有着不可忽视的不利影响;围岩压力随岩土侧压力系数减小、埋深增大、断面尺寸加大而增大;岩土黏聚力增大、内摩擦角增大对提高浅埋隧道围岩稳定性有积极作用。     

Bolt shotcrete support and small pipe groutingtechnology used in treating tunnel collapse

Bolt shotcrete support and small pipe grouting technology are two important elements in the new Austrian tunneling method. We explore the application of bolt shotcrete support and small pipe grouting technology in treating the Huanshanping Span Tunnel col     

软岩地质条件下浅埋隧道锚缩尺模型试验

为研究隧道锚的受力变形和锚碇承载特性等问题,在重庆几江长江大桥工程北岸现场开展1∶30缩尺模型试验。试验结果表明：从相似设计荷载240 kN到1 680 kN,双锚碇前锚面沿拉拔方向的最大位移平均值为0.020~0.808 mm,双锚碇前端上部地表岩体铅直方向的最大位移值为0.028~0.749 mm,双锚碇后端上部地表岩体铅直方向的最大位移值为0.014~0.645 mm;锚碇围岩破裂类型是拉剪复合型破坏;锚碇上方地表横桥方向参与抗拔作用的岩体范围约2~3 m,而沿锚碇轴向参与拉拔作用的岩体破坏区类似一个倒塞体形状;通过试验得到模型锚的可靠抗拉拔承载能力为1 344 kN;模型锚在840 kN下的流变趋于稳定,其长期安全系数为3.5。模型试验结果表明软岩地质条件下浅埋隧道锚具有较高的抗拉拔承载能力,证明此设计方案是可行的。     

Study on dynamic assessment model and its application to tunnel health

This paper uses normalized elements in the sample database to avoid the influence of index type and dimension. Basing on the index system and grade standard of tunnel health safety assessment, it puts forward the relative difference function of variable fuzzy set by the method of set pair analysis and confirming reasonable the relative membership function of the related health indexes in every level and its level standard interval, and develops the assessment model of tunnel health after confirming the relative indexes right by multiplication scale method. Once confirming the eigenvalue of health levels, some samples are given to verify the scientificity and rationality of the method in, the results show that the calculation process is visual, simple, strong currency, result is reasonable and precision is high. The model can be used for various system assessment problems and it’s propitious to promote the more use of variable fuzzy sets in the field of civil engineering.     

Advisable calculation heights of tunnel overlaying soil with earthquake coefficient method

The earthquake coefficient method is used for aseismatic calculation of tunnel in traffic tunnel specification in our country, but the method is not in accordance with the practical engineering and seismic damage when tunnel is buried very deep, because the inertia force of overlaying soil is overestimated. In order to improve the adaptability of earthquake coefficient method, it is necessary to modify it. In this paper, the aseismatic calculation based on earthquake coefficient method is carried out,and the limitation of the method is analyzed. Then earthquake coefficient method, response displacement method, and dynamic analysis method are applied to tunnels’ aseismatic calculation in V class surrounding rock at different widths of the cavity. Finally, the advisable calculation heights of tunnel overlaying soil with earthquake coefficient method in V class surrounding rock is presented, which can be referenced in aseismatic calculation of tunnel engineering.     

Testing and modeling studies on creep characters of supports for tunnel using nonlinear constitutive model

Creep characters of tunnel supports structure is analyzed according to triaxial creep test of concrete specimen of deep tunnel supports structure adopting MTS815 hydraulic servo system. The creep parameters of nonlinear creep model are presented based oncreep curve. The finite element numerical model has been established considering tunnel construction process, creep characters of surrounding rock and support structure. The displacement characteristics, the effective stress and the maximum shear stress in different position in primary support and second lining are obtained through creep characters analysis of surrounding rock and supports structure. The features of displacement and stress dependent time of tunnel supports has visible difference comparing with discard creep effect and calculation displacement and practical monitoring results is basic concordance. The creep characters of surrounding rock and tunnel supports should be considered for deep tunnel.     

Multiple steady states of exhaust airflow in a multi-branch tunnel with the combined effects of buoyancy and fan power

The multi-branch tunnel has multiple routes for smoke extraction and air supply, consequently its ventilation and smoke control modes could have multiple solutions owing to the competitive effects of buoyancy and fan power. For the smoke control of a multi-branch tunnel, the mass and energy balance equations for every possible flow pattern were established, and the corresponding multiple solutions were obtained using mathematical methods. The results demonstrate that, even though the exhaust ventilation mode and fan type have been determined in accordance with the anticipation, multiple states of exhausted flow remain and the operation point of the fans will drift away from the design accordingly. This could cause a totally different direction of smoke route from the anticipated one. It is also shown that the type of fan has significant effects on the existence of multiple solutions.     

Kinematic displacements control simulation and configuration optimizing of six DOFs parallel mechanism for wind tunnel experimental platform

6PUUS parallel mechanism for wind tunnel experimental platform is studied,and its operational principle and movement requirements are analyzed. According to the theory of inverse kinematics and spatial Descartes coordinate transformation of 6PUUS parallel mechanism,kinematic positions of pull rods and kinematic interpolation paths of sliders are derived base on Euler angle of any experimental pose. The detailed algorithm for spatial position interpolation is summarized and its validity is proved by a simulation case in the end. Key factors of nonoccurrence of sliders collision at work are concluded by means of simulation analysis,and combined with the variety of mechanism parameters,optimized size parameters of pull rods and movable platform are also found. It is proved that this method and the simulation algorithm are useful and helpful for the optimizing design and singularity poses analysis of the parallel mechanism.     

基于EFAST的盾构隧道安全指标全局敏感性分析

为了分析地铁隧道健康监测中各个指标之间的相互演化作用关系,提出了一种对监测数据进行分析的数据挖掘思路,将傅里叶幅值灵敏度检验扩展法（EFAST）应用于各项指标的全局敏感性分析中。依据现行隧道安全评价规范,建立反映隧道安全状态的指标体系;通过基于粒子群优化的最小二乘法支持向量机（PSO-LSSVM）,模拟构建了各安全指标函数拟合模型,用以描述隧道各安全指标之间相互作用关系;在此基础上,采用EFAST对该模型的指标进行了全局敏感性分析。结果发现,对隧道安全性影响较大的敏感因素有管片接缝张开宽度、管片接缝接触应力和隧道沉降值;另外,还分析了不同的目标参数、不同的参数取值范围、不同的输入参数的分布形式对参数敏感度值的影响,从不同的角度揭示了盾构地铁隧道中参数的相互作用机理的演化规律。     

Study on flammability and flame-retardant mechanism of modified asphalt for tunnel pavement synergisticly flame retarded by BFR-Ti and ZB

Tunnel fire resistant asphalt can be prepared by mixing SBS modified asphalt and BFR-Ti/ZB. The combustion performances of the SBS modified asphalt/BFR-Ti/ZB and the synergism mechanism of the BFR-Ti and ZB are studied systematically through different methods, such as oxygen index (LOI) method, density of smoke, cone calorimetry, thermogravimetric analysis, etc. The result indicates that compared with SBS modifiedasphalt/BFR-Ti, BFR-Ti/ZB has synergistic effect which can make smoke density, heat release rate(HRR), mass loss rate(MLR) and effective heat of combustion(EHC) of SBS modified asphalt/BFR-Ti/ZB systems significantly decrease while the oxygen index of the SBS modified asphalt/BFR-Ti/ZB and the practice carbon content increase. SBS modified asphalt/BFR-Ti system has significant endothermic-antiflaming mechanism and condensed phase flame-retardance character. SBS modified-asphalt / BFR-Ti/ZB is based on the condensed phase flame-retardance mechanism while with synergistic flame-retardance and endothermic-antiflaming mechanism.     

Analysis About the Stress-strain of Rock when the Small Spacing Tunnel is Broaden or Not

On the background of Yuzhou tunnel at the airport road of Chongqing, it is one small spacing tunnel with serious bias. On` the basis of engineering geology, choose the tunnel section with bias most serious and then build the ANSYS finite element model to simulate the process of broaden. Analyse the surrounding rock displacement, stress strain and plastic zone when the tunnel is broaden or not. Conclusion that in the process of tunnel broading, the displacement of surrounding rock dome downward is big; In addition, as the influence of bias from the surrounding rock above the central rock pillars and right tunnel side wall bears big compressive stress and produces soil plastic deformation. Finally, suggest strengthening the support on the two area above-mentioned in the process of construction.