NUMERICAL ANALYSIS OFFREEZING REINFORCEMENT METHODS OF LARGE-DIAMETER SLURRY SHIELD LAUCHING IN SANDY STRATA

[交通会议论文数据库] AI Cong HE Chuan WANG Yao FENG Kun ZHANG Zhibo

摘要:is with two-tracks and is constructed by large diameter slurry balance shield.The section of shield tunneling

RESEARCH ON EFFECTS OF OBLIQUELY UNDERCROSSING TUNNELING ON EXISTENT TUNNEL

[交通会议论文数据库] LU aiyue MA Zhigang XU Guowen XIA Xin HE Chuan

摘要:　　The mechanical behavior of shield tunnel during approaching excavation has become a common and important problem.The excavation of obliquely undercrossing tunnel was simulated in three-dimensional model by finite element software, and internal force and deformation before and after taking different strengthening stratum thickness were comparative analyzed.The conclusions are as follows:excavation of the newly-built tunnel have little impact on the x-direction displacement of the existent tunnel, and the largest subsidence of the existent tunnel is located at the arch bottom; the undercrossing tunnel has the most apparent impact on the bottom arch of the tunnel, and the impact gradually decreases from bottom arch to vault, while the largest impact occurs at the bottom arch and the smallest impact occurs at vault; the stratum strengthening significantly reduces the settlement of the existent tunnel.

ANALYSIS ON THE INFLUENCE OF ROCK CREEP ON MECHANICAL BEHAVIOR OF SEGMENTAL LINING OF SHIELD MINE INCLINED SHAFT

[交通会议论文数据库] QI Chun HE Chuan FENG Kun WANG ongbing YAN Qixiang HU Xiongyu

摘要:　　It is a new topic constructing long inclined shafts using shield machine or TBM, which is of great significance to shortening shaft construction period, enhancing security and decreasing costs.When crossing through high in-situ stress of deep buried sections, the long-term security of shaft structure may be threatened by rock creep.A numerical model is established considering rock creep to study the influence of shaft depths and segment effective bending rigidity ratios to segment mechanical characteristic index, including bending moment, axial force and safety factor, based on the shield inclined shafts of Shenhua Xinjie Taigemiao Mine Project.The results show that the rock creep influence can last for about 30 days, which leads to the decreasing of maximum bending moment and to the increasing of the safety factor, while has a negligible impact on axial force.With the linear increase of shaft depth, the maximum bending moment as well as the axial force increase approximately linearly, while the safety factor decreases with a slower ratio.Segment effective bending rigidity ratios have a negligible impact on lining bending moment, axial force and safety factor.

盾构隧道变形的无线感知技术研究

[交通会议论文数据库] 黄宏伟 张东明 王飞 何斌 吴俨

摘要:通过室内试验以及现场案例应用得到验证,该方法可以不受运营列车通行影响,真正实现运营隧道全天候实时监控,为隧道安全提供技术支持,有效保障隧道运营安全。

基于三维离散元片体墙-颗粒接触的土压平衡盾构掘进模型

[交通会议论文数据库] 胡雄玉 何川

摘要:　　基于片体墙-颗粒接触理论，以PFC3D和Solidworks为实现平台，将颗粒体与复杂的片体墙实现耦合接触，采用fish语言编译片体墙与颗粒接触处力-位移数据传递交换函数，建立了地层与土压平衡盾构机三维离散元耦合数值模型，其中三维离散元盾构机模型可以实现真实盾构机的主要功能，包括刀盘转动、盾构推进与螺旋出土器出土等。同时从宏-细观角度深入开展砂卵石地层土压平衡盾构掘进对地层扰动和掘进参数研究。研究结果表明：(1)砂卵石地层中刀盘扭矩与总推力较大，其中，总推力中盾壳摩擦阻力占89％；(2)砂卵石地层中盾构土仓压力表现出强烈的非线性；(3)砂卵石地层颗粒间的传力效应明显，刀盘震动与摩擦效应尤为突出，盾构刀盘的切削作用会引起较大范围的土体颗粒旋转运动；(4)砂卵石地层颗粒流动性大，开挖面周围砂卵石颗粒竖向运动趋势明显。

EARTHQUKE INDUCED DISPLACEMENT OF A METRO SUBWAY STATIONTUNNEL IN LIQUEFIABLE GROUND

[交通会议论文数据库] ao Xiaohua Xia Zhifan Ye Guanlin Fu Yanbin

摘要:　　Earthquake-induced liquefaction poses a risk of floatation of underground structures located in liquefiable soil deposits.This failure phenomenon generally occurs when the soil liquefies and loses its shear resistance against the uplift force from the buoyancy of the underground structure, such as tunnels and pipelines.In this paper, the seismic behavior of a shallow rectangular metro tunnel is investigated using an effective stress based soil-water coupling finite element method.The behavior of soils are described by means of a cyclic elasto-plastic constitutive model in which, the stress-induced anisotropy, the density and structure of ground can be described in a unified way.The results showed a matching uplift response of the structure, acceleration, and pore pressure and ground displacement.Special emphasis is given to analyze the result of excess pore water pressures, stress path, acceleration, deformations.The displacement of soil around the structure was confirmed to resemble a flow mechanism from two sides of the structure to its invert which is different from the global circular flow mechanism of circular tunnels.

CHINESE KARST GEOLOGY AND MEASURES TO PREVENT GEOHAZARDS DURING SHIELD TUNNELLING AND DEEP EXCAVATION IN KARST REGION WITH CAVERNS

[交通会议论文数据库] CUI Qinglong SHEN Shuilong Xu Yeshuang WU Huaina WU, Yongxia

摘要:　　Karst landscapes are widely distributed and different characteristics are displayed in different regions due to the effect of various natural environmental factors which occur throughout China.Buried karst cavern systems covered by sandy strata, which are widely distributed in Guangdong Province, possess the following features: high fissure water content, high rock permeability, susceptibility to collapse, variability in shape and an irregular distribution.When a shield tunnel is constructed in this kind of environment, hazards, such as sink holes, the ingress of water or stones, and damage to the constructed tunnels may occur.Thus; karst caves need to be treated before tunnel construction.Socket diaphragm walls are usually adopted to retain soil and to cut-off groundwater during deep excavations in Guangdong province, for the safety of the excavation and to reduce the impact on the surroundings.However, geohazards often occur during the construction of diaphragm walls in karst regions, causing problems such as diaphragm wall collapse, water or mud ingress, ground collapse and long-term instability.This paper presents a procedure for karst cave treatment to mitigate possible hazards during shield tunnelling in karst regions.The construction procedure includes field investigations, judgment, treatment, and effectiveness checks.

土仓排土对土压平衡盾构掘进引起无水砂层响应的影响

[交通会议论文数据库] 瞿同明 王树英 何卫

摘要:　　土压平衡盾构掘进过程中，控制土仓进排土均衡的理想状态往往难以实现，且受监测预报水平、工人技术经验影响，盾构掘进时经常出现挤土情况。

复合地层盾构刀具磨损分析

[交通会议论文数据库] 金大龙 袁大军 李兴高

摘要:通过气压开仓和常压开仓技术，对深圳地铁9号线区间隧道盾构刀具进行现场磨损监测，分析了不同类型刀具在复合地层中的磨损规律，回归得到了不同类型刀具的磨耗系数，在此基础上推算了盾构类似地层条件下的最远掘进距离

盾构开挖面控制引起地层沉降槽宽度系数探讨

[交通会议论文数据库] 秦建设 钟小春 朱东元 朱超

摘要:　　盾构技术在我国地铁建设中得到广泛的应用，盾构施工中由于开挖面支护压力控制不当引起的地面沉降一直是工程关注的重点.在分析盾构施工对地层扰动的基础上，通过Flac3D建立了盾构开挖面稳定分析模型.计算分析了开挖面支护压力与地层损失率的关系