근접굴착시 흙막이벽체 선행하중에 따른 건물 하부 터널의 거동
Behavior of the Tunnel below a Building depending on the Pre-loading on Braced Wall during the Adjacent Ground Excavation
- 주제(키워드) 근접굴착터널 , 선행하중 , 흙막이벽체
- 발행기관 아주대학교
- 발행년도 2011
- 학위수여년월 2011. 2
- 학위명 박사
- 학과 및 전공 일반대학원 건설교통공학과
- 실제URI http://www.dcollection.net/handler/ajou/000000011717
- 본문언어 한국어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
요 약 고도의 산업발전과 경제성장에 따라 도시가 과밀화되고 거대화되면서 지하철, 경전철 등 지하 교통수단 상당수가 건설되었고 고층 등 신설구조물 건설을 위한 깊은 심도의 지반굴착이 빈번하게 행해지고 있다. 그러나 하부에 터널이 통과하는 기존구조물에 인접하여 신설구조물을 시공하기 위해 근접 지반을 굴착하는 경우에 흙막이구조물 뿐 아니라 주변지반 및 인접구조물의 안정성을 확보하는 것이 매우 중요하다. 또한 안정성을 확보할 수 있는 확실한 방안이 절실하다. 따라서 본 논문에서는 건물하중을 받는 기존터널에 근접하여 지반을 굴착할 때 기존터널의 안정을 확보하기 위해 흙막이벽체에 선행하중을 가하는 경우에 대해 연구하였다. 흙막이벽체에 선행하중을 가함에 따른 기존터널의 거동을 확인하기 위해 건물하중의 위치가 기존터널 상부에서 흙막이벽체로부터 0m, 1.0D, 2.0D 일때에 흙막이벽체 버팀대에 선행하중을 가한 경우와 가하지 않은 경우에 대해 대형모형실험과 수치해석을 수행하였다. 건물하중을 받는 기존터널(직경D)이 흙막이벽체로부터 1.0D 이격된 근접굴착에 따른 터널의 거동을 규명하기위해 1/10의 축척으로 대형모형실험을 폭(2.0m), 높이(6m), 길이(4.0m) 크기를 가진 대형토조에서 상대밀도가 일정한 습윤상태의 모래를 30cm씩 다짐한 시험지반을 조성하여 수행하였다. 수치해석은 대형모형실험과 같은 조건으로 모형실험 지반의 토질정수를 현장 및 실내시험에서 구하여 수행하였다. 실험결과 기존터널이 예상 주동활동면 안에 있을 경우에는 흙막이벽체의 수평변위가 발생하면 기존터널 천단부에 침하가 증가하였으나 버팀대에 선행하중을 가하여 수평변위와 배면지반의 거동을 억제시키면 기존터널 내공변위가 원형에 가깝게 복원되어 기존터널의 안정성이 확보됨을 알 수 있었다. 반면 기존터널이 예상 주동활동면 밖에 있을 경우에는 흙막이벽체에 수평변위가 발생되더라도 기존터널의 내공변위가 작게 발생되어 선행하중을 가하지 않아도 기존터널의 안정성을 확보할 수 있다는 것을 확인하였다. 결론적으로 건물하중을 받는 기존터널이 예상 주동활동면 안에 있을 경우에는 선행하중을 가하여 안정성을 확보할 수 있었고, 건물하중을 받는 기존터널이 예상 주동활동면 밖에 있을 경우에는 선행하중을 가하지 않아도 안정성을 확보할 수 있다는 것이 확인되었다.
more초록/요약
Abstract As the urban areas were expanded and overpopulated with the industrial development and economic growth, various ways for the underground transportation, such as subway and light rail, have been constructed. Deep ground excavation adjacent to the existing structures is not seldom in the urban areas, in order to construct the new structures like skyscrapers. When the new building is constructed adjacent to the existing tunnel, which is located under a building, the tunnel is very sensitive to the construction sequences for the new building. In this case, it is very important to secure the stability of the braced wall, the surrounding ground, and adjoined structures. But it is not enough studied yet. In this study, it was tried to apply the pre-loading on the braced wall in order to secure the stability of the existing tunnel which was already loaded by the building above it, when the adjacent ground would be excavated. To examine the behavior of existing tunnel large-scale model tests and numerical analyses were carried out for the cases, when the pre-loading was applied to the braced wall. And they were also performed for the cases without pre-loading. In the tests, the location of building, the pre-loads on the braced wall, and the loads due to the structures were varied. In order to study the behavior of the existing tunnel during the ground excavation behind the braced wall, large scale model tests in a scale of 1:10 were carried out in the large test box with dimensions of 2.0m (width), 6m (height), and 4.0m (length), which was filled with wet sand with the natural water content in a constant density. Numerical analyses were conducted under the same conditions as the large scale model tests. Soil parameters of the test ground were determined from the field and the laboratory experiments. Test results showed that, the crown of the existing tunnel sunk in a large amount when the braced wall was deformed horizontally if the tunnel was existed inside the active failure zone. But if the movement of the rear ground and the horizontal displacement was restrained by the pre-loading on the braced wall, the convergence of the existing tunnel was restored almost to its original form, which could secure the stability of the existing tunnel. On the contrary, when the existing tunnel was located outside the active failure zone, the stability of the existing tunnel could be secured without pre-loading, because the deformation of the existing tunnel was very small even if the horizontal displacement of braced wall took place. In conclusion, when the existing tunnel was located inside the expected active failure zone, the stability of the tunnel could be secured by applying pre-loading. But when the existing tunnel was located outside the expected active failure zone, the stability of the tunnel could be secured without pre-loading.
more목차
제 1 장 서 론 1
1.1 연구배경 및 목적 1
1.2 연구내용 및 범위 3
제 2 장 이론적 배경 4
2.1 지중응력 4
2.1.1 지중 수평응력 4
2.1.2 임의점의 응력상태 6
2.1.3 등분포 연직 띠하중에 의한 지중응력 8
2.1.4 원형터널 주변의 지중응력 10
2.2 토압 12
2.2.1 고전토압이론 12
2.2.2 토압의 형태 15
2.2.3 토압계수 16
2.2.4 벽체의 변위와 토압 17
2.2.5 정지토압 19
2.2.6 전이토압 20
2.2.7 증가토압 21
2.2.8 기존건물에 의한 토압 22
2.3 선행하중 작용 시 흙막이벽체의 거동과 토압의 영향 25
2.4 근접시공에 따른 기존구조물의 영향범위 26
2.5 근접시공에 의한 기존 터널이 받는 영향 30
2.6 지반과 터널라이닝의 강성 33
제 3 장 대형모형실험 36
3.1 대형모형실험 개요 36
3.2 대형모형실험 지반의 특성 37
3.2.1 물리적 특성 37
3.2.2 역학적 특성 38
3.3 대형모형실험 장치 39
3.3.1 대형모형 토조 39
3.3.2 모형터널 및 흙막이벽체 41
3.3.3 계측기기 및 장비 45
3.4 대형모형실험 방법 47
3.4.1 대형모형실험 지반조성 48
3.4.2 계측기 및 장비 설치 48
3.4.3 기존건물 52
3.4.4 터널라이닝 사전검측 53
3.4.5 대형모형실험 순서 55
3.4.6 대형모형실험 진행 58
3.5 대형모형실험 결과 59
3.6 대형모형실험 결과 분석 60
3.6.1 흙막이벽체의 수평변위 60
3.6.2 흙막이벽체의 부재력 63
3.6.3 터널의 내공변위 67
3.6.4 터널의 부재력 68
3.6.5 지표침하 71
제 4 장 수 치 해 석 73
4.1 해석프로그램 및 경계조건 73
4.2 해석방법 및 입력물성치 74
4.3 수치해석 결과 75
4.3.1 흙막이벽체 배면에 터널이 없는 경우 75
4.3.2 흙막이벽체 배면에 터널이 있는 경우 76
4.4 수치해석 결과분석 77
4.4.1 흙막이벽체의 수평변위 77
4.4.2 흙막이벽체의 부재력 80
4.4.3 터널의 내공변위 84
4.4.4 터널의 부재력 85
4.4.5 지표침하 88
제 5 장 분석 및 고찰 90
5.1 기존건물 위치에 따른 분석 90
5.1.1 흙막이벽체의 수평변위 90
5.1.2 흙막이벽체의 부재력 98
5.1.3 터널의 내공변위 114
5.1.4 터널의 부재력 118
5.1.5 지표침하 130
5.2 건물하중을 받는 터널의 근접굴착에 따른 선행하중 138
5.3 건물하중을 받는 터널의 근접굴착에 따른 영향분석 140
5.3.1 흙막이벽체로부터 터널의 이격거리 1.0D일 경우 141
5.3.2 흙막이벽체로부터 터널의 이격거리 2.0D일 경우 143
5.4 고 찰 145
제 6 장 결 론 146
참 고 문 헌 148
목차
List of Figure
Fig. 2.1 Stress distribution in the elastic half space due to gravity 4
Fig. 2.2 Stress distribution in the elastic half space due to gravity and uniformly
distributed surcharge 5
Fig. 2.3 Stress in the arbitrary in the ground 6
Fig. 2.4 Mohr's stress circle 7
Fig. 2.5 Stress distribution in the saturated ground due to gravity and
pore water pressure 8
Fig. 2.6 Mohr's circle and Stress due to uniform vertical load on an
infinite strip 9
Fig. 2.7 Pressure bulb due to strip line load 10
Fig. 2.8 Stress in the elastic ground around the circular tunnel
(Kirsch 1898) 11
Fig. 2.9 Earth pressure of Coulomb 13
Fig. 2.10 Earth pressure of Rankine 14
Fig. 2.11 Type of earth pressure 15
Fig. 2.12 Coefficient of earth pressure due to the wall movement 16
Fig. 2.13 Distribution of the earth pressure on braced wall due to the wall
displacement and the active earth Pressure(Ohde,1938) 18
Fig. 2.14 Apparent earth pressure of the braced wall 20
Fig. 2.15 Type of apparent earth pressure 21
Fig. 2.16 Horizontal earth pressure for vertical belt load 24
Fig. 2.17 Earth pressure and horizontal displacement of the braced wall due
to pre-loading 25
Fig. 2.18 Influenced area due to the horizontal displacement of braced wall in
sandy soil 27
Fig. 2.19 Influenced due to the horizontal displacement of braced wall in
cohesive soil 27
Fig. 2.20 Influenced area due to the pull-out of braced wall 28
Fig. 2.21 Influenced area due to the heaving of braced wall 29
Fig. 2.22 Stress, strain and displacement distribution in the ground around
the tunnel 31
Fig. 2.23 Streamline around the cylinder shape obstacle 32
Fig. 2.24 Effect of flexibility ratio of the tunnel lining 33
Fig. 2.25 Maximum bending moment depending on the stiffness ratio of ground
tunnel lining (Duddeck and Erdman, 1985) 35
Fig. 3.1 Schematic diagram of the model test box 36
Fig. 3.2 Grain size distribution curve of test ground 37
Fig. 3.3 Physical test equipments of the ground 37
Fig. 3.4 Result of direct shear tests of the test ground 38
Fig. 3.5 Bearing capacity-Settlement curve of plate loading test 38
Fig. 3.6 Schematic diagram of the model test box 39
Fig. 3.7 Front view of the model test box 40
Fig. 3.8 Minimize the friction in the side wall of test box 40
Fig. 3.9 Screw jack 41
Fig. 3.10 Hydraulic jack 41
Fig. 3.11 Installation of tunnel lining · 43
Fig. 3.12 Data acquisition systems used for model tests 46
Fig. 3.13 Measuring sensors for model tests 46
Fig. 3.14 Schematic diagram of loading conditions 47
Fig. 3.15 Compaction test ground 48
Fig. 3.16 Installation of LVDT for the braced wall 48
Fig. 3.17 Installation of strain gauge for the braced wall· 48
Fig. 3.18 Installation of LVDT for the tunnel lining · 49
Fig. 3.19 Installation of strain gauge for the tunnel lining 49
Fig. 3.20 Installation of displacement gauges for ground surface settlement 50
Fig. 3.21 Installation of earth pressure gauge 51
Fig. 3.22 Concentrated loading system 52
Fig. 3.23 Test of tunnel lininig 53
Fig. 3.24 Results of tunnel lininig 54
Fig. 3.25 System for the model test 55
Fig. 3.26 Flow chart for the model test 57
Fig. 3.27 Horizontal displacement of the braced wall without tunnel 61
Fig. 3.28 Horizontal displacement of the braced wall with tunnel 62
Fig. 3.29 Moment of the braced wall without tunnel 63
Fig. 3.30 Shear force of the braced wall without tunnel 64
Fig. 3.31 Moment of the braced wall with tunnel 65
Fig. 3.32 Shear force of the braced wall with tunnel 66
Fig. 3.33 Displacement of the tunnel lining 67
Fig. 3.34 Moment of the tunnel lining 68
Fig. 3.35 Shear force of the tunnel lining 69
Fig. 3.36 ShearAxial force of the tunnel lining 70
Fig. 3.37 Ground surface settlement without tunnel 71
Fig. 3.38 Ground surface settlement with tunnel 72
Fig. 4.1 Mesh generation and boundary conditions for the finite element
analysis 73
Fig. 4.2 Horizontal displacement of the braced wall without tunnel 78
Fig. 4.3 Horizontal displacement of the braced wall with tunnel 79
Fig. 4.4 Moment of the braced wall without tunnel 80
Fig. 4.5 Shear force of the braced wall without tunnel 81
Fig. 4.6 Moment of the braced wall with tunnel 82
Fig. 4.7 Shear force of the braced wall with tunnel 83
Fig. 4.8 Displacement of the tunnel lining 84
Fig. 4.9 Moment of the tunnel lining 85
Fig. 4.10 Shear force of the tunnel lining 86
Fig. 4.11 Axial force of the tunnel lining 87
Fig. 4.12 Ground surface settlement without tunnel 88
Fig. 4.13 Ground surface settlement with tunnel 89
Fig. 5.1 Wall displacement without surface load(without tunnel) 91
Fig. 5.2 Wall displacement without surface load(with tunnel) 91
Fig. 5.3 Wall displacement of surface loading in 0m(without tunnel) 92
Fig. 5.4 Wall displacement of surface loading in 0m(with tunnel) 93
Fig. 5.5 Wall displacement of surface loading in 1D(without tunnel) 94
Fig. 5.6 Wall displacement of surface loading in 1D(with tunnel) 95
Fig. 5.7 Wall displacement of surface loading in 2D(without tunnel) 96
Fig. 5.8 Wall displacement of surface loading in 2D(with tunnel) 97
Fig. 5.9 Moment of the braced wall without surface load(without tunnel) 98
Fig. 5.10 Shear force of the braced wall without surface load(without tunnel) 99
Fig. 5.11 Moment of the braced wall without surface load(with tunnel) 100
Fig. 5.12 Shear force of the braced wall without surface load(with tunnel) 101
Fig. 5.13 Moment of the braced wall with surface loading in 0m(without tunnel) 102
Fig. 5.14 Shear force of the braced wall with surface loading in 0m(without tunnel) 103
Fig. 5.15 Moment of the braced wall with surface loading in 0m(with tunnel) 104
Fig. 5.16 Shear force of the braced wall with surface loading in 0m(with tunnel) 105
Fig. 5.17 Moment of the braced wall with surface loading in 1D(without tunnel) 106
Fig. 5.18 Shear force of the braced wall with surface loading in 1D(without tunnel) 107
Fig. 5.19 Moment of the braced wall with surface loading in 1D(with tunnel) 108
Fig. 5.20 Shear force of the braced wall with surface loading in 1D(with tunnel) 109
Fig. 5.21 Moment of the braced wall with surface loading in 2D(without tunnel) 110
Fig. 5.22 Shear force of the braced wall with surface loading in 2D(without tunnel) 111
Fig. 5.23 Moment of the braced wall with surface loading in 2D(with tunnel) 112
Fig. 5.24 Shear force of the braced wall with surface loading in 2D(with tunnel) 113
Fig. 5.25 Displacement of the tunnel lining without surface loading 114
Fig. 5.26 Displacement of the tunnel lining with surface loading in 0m 115
Fig. 5.27 Displacement of the tunnel lining with surface loading in 1D 116
Fig. 5.28 Displacement of the tunnel lining with surface loading in 2D 117
Fig. 5.29 Moment of the tunnel lining without surface load 118
Fig. 5.30 Shear force of the tunnel lining without surface load 119
Fig. 5.31 Axial force of the tunnel lining without surface load 120
Fig. 5.32 Moment of the tunnel lining with surface loading in 0m 121
Fig. 5.33 Shear force of the tunnel lining with surface loading in 0m 122
Fig. 5.34 Axial force of the tunnel lining with surface loading in 0m 123
Fig. 5.35 Moment of the tunnel lining with surface loading in 1D 124
Fig. 5.36 Shear force of the tunnel lining with surface loading in 1D 125
Fig. 5.37 Axial force of the tunnel lining with surface loading in 1D 126
Fig. 5.38 Moment of the tunnel lining with surface loading in 2D 127
Fig. 5.39 Shear force of the tunnel lining with surface loading in 2D 128
Fig. 5.40 Axial force of the tunnel lining with surface loading in 2D 129
Fig. 5.41 Ground surface settlement without surface load(without tunnel) 130
Fig. 5.42 Ground surface settlement without surface load(with tunnel) 131
Fig. 5.43 Ground surface settlement with surface loading in 0m(without tunnel) 132
Fig. 5.44 Ground surface settlement with surface loading in 0m(with tunnel) 133
Fig. 5.45 Ground surface settlement with surface loading in 1D(without tunnel) 134
Fig. 5.46 Ground surface settlement with surface loading in 1D(with tunnel) 135
Fig. 5.47 Ground surface settlement with surface loading in 2D(without tunnel) 136
Fig. 5.48 Ground surface settlement with surface loading in 2D(with tunnel) 137
Fig. 5.49 Magnitudes of the pre-loading on the braced wall without tunnel 138
Fig. 5.50 Magnitudes of the pre-loading on the braced wall with tunnel 139
Fig. 5.51 Influenced area due to the horizontal displacement of braced wall 140
Fig. 5.52 Wall displacement(In case of 1.0D distance from braced wall to tunnel) 141
Fig. 5.53 Tunnel displacement(In case of 1.0D distance from braced wall to tunnel) 142
Fig. 5.54 Wall displacement(In case of 2.0D distance from braced wall to tunnel) 143
Fig. 5.55 Tunnel displacement(In case of 2.0D distance from braced wall to tunnel) 144
목차
List of Tables
Table 2.1 Magnitude of the wall movement for development of active and
passive state (△x/h) 17
Table 2.2 Increase earth pressure due to the wall displacement 22
Table 3.1 Physical properties of the test ground 38
Table 3.2 Stiffness ratio and thickness of the model tunnel lining 43
Table 3.3 Thickness of the model braced wall 44
Table 3.4 Reduction ratio of the model test 45
Table 3.5 Data acquisition system 45
Table 3.6 Measuring sensors 46
Table 3.7 Labels of loading conditions · 58
Table 3.8 Results of the model test 59
Table 4.1 Mechanical properties of used in numerical analysis 74
Table 4.2 Labels of loading conditions 75
Table 4.3 Results of numerical analysis for braced wall and ground without
tunnel 76
Table 4.4 Results of numerical analysis for braced wall and ground 76
