桩荷载对粘土隧道结构影响的数值分析

发布时间：2022-10-30 09:20

　　通过对相关文献的调查研究,可以发现目前桩荷载对既有隧道的影响没有得到足够的重视。为保证隧道结构的安全可靠,研究不同土体中桩荷载对既有隧道结构力学响应的影响规律就显得十分重要。因此,本文采用有限元分析软件Plaxis,选取红土和上海、博姆、曼谷的典型粘土地层,分析了不同地层临近既有桩基对隧道结构力学响应的影响规律,进一步阐述了桩和隧道之间的相互作用机理。首先,本文对比分析了红土与其它粘土地层中隧道的弯矩、轴力、剪力及变形,揭示了红土地层对隧道结构的特殊影响。结果表明,与其它地层相比,红土地层中隧道弯矩和剪力明显较大,轴力则无明显区别,隧道变形有大有小。其次,本文研究了用于隧道衬砌上的桩承载效应的二维平面应变模型,以确定二维平面应变模型是否能较为接近的模拟三维模型的力学状态,并且分析何种情况下三维模型能够简化为二维平面应变模型。结果表明二维模型高估了桩的荷载效应,尤其在衬砌的位移方面。因此,二维模型应谨慎使用,且其结果只能作为一个大概值。此外,本文还研究了桩荷载在不同地层中对隧道力学响应的影响,主要分析因素为土体刚度、静止土压力系数和桩与承台连接情况。结果表明:桩荷载效应较大程度上取决于土... 

【文章页数】：107 页

【学位级别】：硕士

【文章目录】：
ACKNOWLEDGMENTS
摘要
ABSTARCT
LIST OF SYMBOLS
1 INTRODUCTION
    1.1 Problem Statement
    1.2 Scope
    1.3 Thesis Outline and Workflow
2 LITERATURE REVIEW
    2.1 Pile Tunnel Interaction Problem
    2.2 Lateritic Soils
        2.2.1 Mineral Composition, Physical and Mechanical Characteristic of Lateritic Soils
        2.2.2 Engineering Characteristics of Lateritic Soils
        2.2.3 Constitutive Models and Features for Lateritic Soils
        2.2.4 The Mohr- Coulomb's Model
        2.2.5 The Hardening Soil Model
        2.2.6 Response Characteristics of Lateritic Soils to Tunnelling
    2.3 Shanghai soft clay, Bangkok soft and stiff clays, Boom clay and London clay
    2.4 Modelling Approach of Tunnel Problems
        2.4.1 Modelling of Pile Group Effect on Tunnels
        2.4.2 Embedded Piles in Plaxis 3D
        2.4.3 Embedded Pile Row Element in Plaxis 2D
        2.4.4 Induced Structural Forces in Tunnel Lining due to Pile Loads
3 3D COMPARATIVE ANALYSES OF FORCES AND DISPLACEMENTS OF TUNNEL LININGS IN CLAYS
    3.1 Selection of Appropriate Soil Constitutive Models
    3.2 Comparing Lining Force for Tunnels in Lateritic soil, Shanghai soft clay, Bangkok softclay, Bangkok stiff clay, Boom clay and London clay
    3.3 Modelling Approach
    3.4 3D Model for Step-by-Step Validation
    3.5 Parametric Analyses
    3.6 Results
        3.6.1 Ground Surface Settlements
        3.6.2 Lining Forces and Displacements
        3.6.3 Influence of Soil Parameter on the Mechanical Response of the Tunnel Lining inLateritic Soils
4 COMPARING THE EFFECTS OF PILE GROUP LOADS ON TUNNEL LINING USING 2D AND 3DMODELS
    4.1 Finite Element Analyses
        4.1.1 Determining Load Capacity of Pile
        4.1.2 Finite Element Model for 2D Plain Strain Analyses
        4.1.3 Validity of the 2D Plain Strain Model
        4.1.4 Finite Element Model for 3D Analyses
        4.1.5 Constitutive Model and Material Properties for 2D Model
        4.1.6 Constitutive Model and Material Properties for 3D Model
        4.1.7 Numerical Simulation of the Pile-Tunnel Interaction
    4.2 Results
5 EFFECTS OF PILE GROUP LOADS ON TUNNEL LINING IN SOFT AND STIFF CLAYS USING A 3DMODEL
    5.1 Model Geometry and Boundary Conditions
    5.2 Material Parameters and Constitutive Models
    5.3 Determination of Allowable Design Load of the Piles within the Various Clays
    5.4 Numerical Analyses Procedure for the Studies
    5.5 Model Validation
    5.6 Results
        5.6.1 Comparing Pile Loads Effects on Tunnel Lining in Lateritic Soil, Bangkok Stiff Clayand Bangkok Soft Clay
        5.6.2 Accessing the Influence of Soil Stiffness Modulus(E_(50)~(ref)) and At -Rest EarthPressure Coefficient (Ko) on Pile Group Load Effects on Tunnel Lining
        5.6.3 Influence of Pile Head Connection on Pile Group Load Effects on Tunnel Lining
        5.6.4 Influence of Pile length on the Pile Group Load Effects on Tunnel Lining
6 CONCLUSIONS
REFERENCES
A FORM


【参考文献】：
期刊论文
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[3]上海浅层地基土的前期固结压力及有关压缩性参数的试验研究[J]. 魏道垛,胡中雄.  岩土工程学报. 1980(04)



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