Deformation Properties of Backfill Grouting in Shield Tunnel

Utilizing the self made unit body model test apparatus, the deformation laws of backfill grouting were studied under different grouting pressures, different soil conditions and different ground water pressures. It was shown that high grout pressures can accelerate the consolidation rate of grout drainage and increase final deformation amount. And soil permeability coefficient was an important factor to grout deformation. The ground water pressure was more important for sand soil while the grout pressure was for clay soil. The proposed apparatus can truly reflect stress status of grout injected to tail void. And grout deformation properties were helpful to clarify the stratum stress release and stratum deformation of backfill grouting.      

Mechanical and Deformation Characteristicson Shield Tunnel Segment with Cracks

The 3D Goodman element is used to simulate segments' cracks in one section of shield tunnel in Guangzhou. Mechanical and deformation characteristics of segment structure responded to varied depth of cracks is analyzed in this paper. Meanwhile, research on coefficient of lateral earth pressure, soil coefficient and ground water level on mechanical and deformation characteristics is carried out. The research result shows that along with the increase of cracks' depth, the tensile stress, pressure stress reach the maximum value while the increment is not too much. However, when the depth equals to the thickness of segment, the reinforcements' tensile stress has increase sharply, even exceeded the allowable value. Moreover, the maximum number of tensile stress, horizontal and vertical convergent value of shield tunnel segment with cracks increase with the reduction of the coefficient of lateral earth pressure and soil coefficient, and increase with the increase of ground water level as well. Specific repair measure has been taken to segments' cracks in this section of shield tunnel based on the conclusions. In general, this section of shield tunnel is stable and safe now, and there is no longer new cracks appeared.     

Numerical simulation analysis on small clear spacing crossing viaduct pile foundation of shielded subway tunnels

Aimed at the problem of the in partial section of the Nanjing Metro Line 3, the three-dimensional pattern of tunnel, segment and pile foundation was established after appropriate simplification. The simulation results showed that, the Overpass pile foundation of Shield Tunneling to Adjacent Metro Shield Tunnel will have effect on the force and deformation of the earth's surface and pile foundation, the maximum deformation value of the earth's surface is larger than that of the pile foundation top, stress concentration appeared in right working slope lower side segment of tunnel. Through the comparison with field monitoring results, the field dates is consistent with the Numerical Simulation Results, the execution parameters are advised to be well controlled in the further construction, in the same time strengthing the track monitoring, tracking grouting reinforcement should be carried when necessary. The research results could provide reference for the smooth going of the project.     

Upper Bound Solution of the Limit Support Pressure during Shield Tunneling in Soft Clay

Considering the nonhomogeneity and anisotropy of the undrained shear strength of soft clay, the face stability of shield tunnel was studied by upper bound limit analysis, and the formula for calculating the limit support pressure was obtained. The influences of nonhomogeneity and anisotropy on the limit support pressure amplify with each other.The relationship between limit support pressure and tunnel depth also depends on the nonhomogeneity and anisotropy; the limit support pressure reaches maximum value at a certain tunnel depth when nonhomogeneity and anisotropy are strong enough. These results show the nonhomogeneity and anisotropy of clays cannot be neglected when analyzing the stability of tunnel face.     

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。     

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.     

莼菜种子内源抑制物质生理活性的研究

采用蒸馏水、甲醇和丙酮3种溶剂浸提莼菜种子,研究其浸提液对小白菜种子发芽及幼苗生长的影响.结果表明:3种溶剂浸提莼菜种子内源抑制物质的活性不同,以蒸馏水浸提液的抑制物质活性最强,甲醇浸提液和丙酮浸提液的抑制活性较弱;蒸馏水浸提液对小白菜种子的抑制作用随浸提液浓度的增加而增强;采用45℃温水浸泡莼菜种子可有效去除部分内源抑制物质.     

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.     

Model test of influence of excavating new interchange tunnel on existing tunnel

In order to analyze the influence of construction of new interchange tunnel on existing tunnel, a three-dimension model test of interchange tunnel is carried out with the system of structure and surrounding rockmass of highway tunnel. Existing tunnel’s surrounding rock pressure, internal displacement and supporting internal force are measured. The results show that, firstly, excavating new tunnel has obvious influence on section Ⅰ of existing tunnel, and has little influence on section Ⅱ.All surrounding rock pressure keeps decreasing and arch bottom surrounding rock’s stability reduces. Secondly, crown and hance internal displacement manifest tensile deformation, and the deformation at crown is bigger than that at hance. Thirdly, exiting tunnel’s supporting axial force keeps increasing and supporting moment keeps decreasing. Finally, excavating new interchange tunnel has obvious influence on exiting tunnel’s surrounding rock pressure, internal displacement and supporting internal force when adjacent space is 0.25D, and it indicates that interchange tunnel’s adjacent space should be no less than 0.5D.     

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.     

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.     

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.     

Dynamic Prediction Analysis of Surrounding Rocks Stability for Non-symmetric Double-Arch Highway Tunnel

During the construction of non-symmetric double-arch rock highway tunnel, the complicated geological condition may affect the safety of the constructor and the engineering quality. In this paper, two treatment methods are put forward. At first, the site monitoring of surrounding rock displacement must be carried out, then, BP neural network is applied in predicting the displacement of surrounding rock based on the learning sample of measured value, so the stability of surrounding rocks may be analyzed and forecasted. During the analysis of BP neural network, the effects of joint and fracture of surrounding rock on displacement can be comprehensively considered, comparing the predicted values of displacement with those by FEM. The results show that not only the predicted error of BP neural network is relative small, but the predicted values of surrounding rock displacement are close to measured ones. So, the predicted values of BP neural network are reliable and may guide the engineering construction in site.     

Structual Dynamic Characteristics Analysis and Improvement for Two-way Branch Exhaust Pipe Shield

The two-way branch exhaust pipe shield is the main source of surface radiate noise of a vehicle's engine.(Using) the finite element analysis software ANSYS,a finite element model of the shield is established,and then the(modal) analysis is done theoretically with this model,the result is consistent with the experiment.The result shows that this finite element model can be used for the next structual dynamic characteristics analysis.With this model,the relationship of structural parameter,structural style of the shield and the corresponding vibrative modal is analyzed.The(optimal) improved measures are adopted which is based on the practical structure of the shield.The analysis of the(improved) structure shows that the increase of natural vibration frequency is visible,the vibration noise of the shield is suppressed distinctly.     

Solving Method for Soil Spring Stiffness of Shallow Shield Tunneling

Based on complex variable theory in plane elasticity, the equivalent spring stiffness is derived from the analytical solution by means of simplifying shallow shield tunneling to semi-infinite plane with hole, which is applied to response displacement method. The performances of the analytical solution are evaluated and compared with that of the deep shield tunneling through a series of selected various tunnel depths and soil Poisson's ratios. The relation of compression and shear spring stiffness is discussed. Meanwhile, two factors affected soil spring stiffness, tunnel depth and soil Poisson's ratio, are also analyzed. It is shown that soil spring stiffness of shallow shield tunneling is different from that of deep shield tunneling, and the ratio of compression and shear spring stiffness varies along shallow shield tunneling. It is also found that the value and distribution law of soil spring stiffness of shallow shield tunneling greatly depend on tunnel depth and soil Poisson's ratio.     

改进塑料薄膜小型拱棚温、光条件的措施及其效果

通过观测、考察拱棚在春前加强保温,秋后提早盖苫蓄热是目前提高内部气温和土壤温度、延长应用时期的主要方法。由于受生产条件的限制,常因覆盖物遮阳在北侧形成弱光带,这是亟待改进的问题。     

Thermo-mechanical coupling analysis of shield cutter head under mud cake condition

Aiming at the cutter head thermal damage and other failure problems caused by shield cutter head mud formation in residue and clay soil,the problem of thermal-stress coupling of shield cutter head under the effect of mud in the tunnelling process is studied,and the cutter head temperature and thermal-stress distribution of coupling fields under mud effect are acquired. A shield cutter head three-dimensional finite element model is built by using software ANSYS and Solidworks. The results shows that when the mud is formed,the temperature rises sharply in a short time,which leads to a rapid increase of thermal stress to 168.2 MPa,at the same time,the maximum thermal deformation reaches 3.1 mm,then the center of cutter head is wrapped.     

Prediction of Ground Surface Movements Due to Shield Tunneling with Tail Grouting Heave

Compared with conventional tunneling methods, ground movements behave some different patterns, such as surface heave induced by tail grouting. Through the analysis of ground surface heave due to tail grouting in three cases, the applicability of Gaussian equation and six analytic methods (including Mindlin's problem, Sagaseta method, Verruijt-Booker method, Loganathan-Poulos method, Chi method and Park method) to predict ground surface heave induced by tail grouting were verified. Based on case studies, one modified Peck equation was proposed to calculate ground surface movements, including grouting heave due to shield tunneling. The results show that the Gaussian equation and Chi method are applicable to calculate surface heave due to shield tail grouting, and the Modified Peck Equation can predict the total transversal ground surface movements rationally.     

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。