VIETNAM NATIONAL UNIVERSITY, HANOI VIETNAM JAPAN UNIVERSITY TRAN QUANG DUC MINIMIZING THE INFLUENCE ON EXISTING BUILDINGS WHEN TUNNELING IN SOFT SOIL 1 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com VIETNAM NATIONAL UNIVERSITY, HANOI VIETNAM JAPAN UNIVERSITY TRAN QUANG DUC MINIMIZING THE INFLUENCE ON EXISTING BUILDINGS WHEN TUNNELING IN SOFT SOIL MAJOR: MASTER OF INFRASTRUCTURE ENGINEER CODE: ………………… RESEARCH SUPERVISOR: Dr. NGUYEN TIEN DUNG Dr. VU MINH NGAN Hanoi, 2019 2 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com ACKNOWLEDGEMENT 3 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com ABTRACT 4 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com CONTENT ACKNOWLEDGEMENT. 10 CHAPTER 2 LITERATURE REVIEW .3 Finite element method using software Plaxis 2D .2 Project case study .1 Main properties of Tunnel in HCM MRT line1 .2 Construction sequence of underground tunnel .3 Collection of soil condition data.1 Soil investigation data .4 Collection of TBM’s operation data .5 Selection of analysis section .6 Ground settlement analysis by empirical method .7 Numerical analysis with Plaxis 2D.
23 5 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.2 Preparation input data .3 Soil input parameters in Plaxis 2D .4 Properties of tunnel segment .7 Stress reduction method .8 Collection of monitoring data. 30 CHAPTER 4 RESULT AND DISCUSSION. 33 Ground surface settlement of the tunnel alignment.1 Ground surface settlement of the tunnel alignment .2 Ground surface settlement in tunneling period .2 TBM’s operational parameters and its effect on settlement .3 Analysis of ground surface settlement by Empirical method .1 Trough width parameter (i) .4 Analysis of ground surface settlement by Plaxis 2D .2 Stress reduction method .5 Comparisons of empirical method and numerical method. 45 CONCLUSIONS AND RECOMMENDATIONS.
46 6 LUAN VAN CHAT LUONG download : add luanvanchat@agmail. 52 APENDIX A: TUNNEL MACHINE AND LINNING SEGMENT. 67 APENDIX B: GEOLOGY PROFILE. 70 APPENDIX C: CROSS BUILDING STRUCTURE.
73 7 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com CHAPTER I INTRODUCTION 1.1 Background In Vietnam, big cities such as Hanoi and Ho Chi Minh have reached approximately 10 million population, not including the sub-urban people residing and commuting due to the recent rapid urbanization. This creates a dramatically pressure on the infrastructure system and the public transport system. Construction of MRT with underground sections is the optimal and feasible solution to solve these problems of the cities. System map (planned) for Hanoi MRT system to vision 2050 (Hanoi Metropolitan Railway Management Board) 8 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.
System map (planned) for Hochiminh city MRT system to vision after 2020 (HCMC urban railway management board) In bored tunel in urban areas, bored tunel with TBMs has recently been a popular and effective method in the world. This technique has been developed and applied as a main method for underground MRT projects. The two cities of Hanoi and Ho Chi Minh City are located at the center of the delta with geology condition a mostly consisted of soft soil. Deformations including settlements and tilts should be well controlled when bored tunnel in order to protect the existing ground surface and minimize the impacts on existing structures.
By combining theoretical calculation, software analysis and comparison with monitoring data, results derived from this study can be applied for the bored tunnel design and construction in 9 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com geo-conditions in Vietnam in order to obtain effective and safe bored tunnel projects.2 Outline research There are five chapters in this thesis. Chapter 1 is the introduction presenting the background of bored tunnel work and outline of the thesis. Reviewing the theoretical to calculate the displacement of existing structures during and after the TBM drilling process is indicated in Chapter 2. Chapter 3 shows the displacement calculation carried out by finite element method to predict the degree of influence on existing works as well as the optimal efficiency.
Chapter 4 describes a comparison between theoretical and numerical results with monitoring data in case study in Ho Chi Minh City Metroline 1 project to verify methods of predicting settlement displacement. Proposing solutions based on calculated and observed results has been derived in Chapter 5. 10 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com CHAPTER 2 LITERATURE REVIEW 2.1 Empirical method According to Mair and Taylor (1999), ground construction surface movement due to main reasons movement in follow location: bored machine face, along the shield, behind the shield at tail, and consolidation settlement.1 shows the 3D settlement trough on the surface. First author, Peck (1969) firstly proposed the settlement trough on the surface due to TBM operation in soft soil as a Gaussian distribution.
Some the other authors have confirmed that theoretical (Cording and Hansmire, 1975; Mair et al. Although some different opinions with Gaussian distribution in some particular cases (Jacobsz, 2003; Vorster, 2006; Farrell et al., 2012) and in Japan (JSSMFE, 1993), the Gaussian still curve commons using in study and industry practice.1 Surface settlement trough induced by bored tunel (Franzius, 2004) In this study, the Gaussian curve is used to investigate the ground movement when bored 11 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com tunel in order to find the effects on existing structures. It is can be estimated from the maximum settlement Gaussian distribution (Peck, 1969) Figure 2.2 Transverse settlement tunnel trough due to bored TBM (Peck, 1969) In order to forecast surface settlement (Peck, 1969) and subsurface settlement (Mair et al., 1993), the volume loss is often taken by experience and data from existing cases. It is make hardly to assessment the volume loss as generalize.
In next chapter, the further detail with factors determine settlement will be presented, especially volume loss. Based on Attewell and Farmer (1974), Cording and Hansmire (1975) and Mair and Taylor (1999), the volume loss can obtain by divided component similar settlement: - Volume loss at the front face of TBM - Volume loss at along TBM; - Volume loss at behind TBM tail; - Volume loss behind the shield tail induced by consolidation Function to determine volume loss as following: VL = VL,f +VL,s +VL,t +VL,c Where VL,f is volume loss at the front face of TBM, VL,s Volume loss at along TBM, VL,t is volume loss at behind TBM tail , and VL,c is volume loss behind the shield tail induced by consolidation. 12 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com With the independent calculation, theoretical can compare with analytical and monitoring from case study in practice.2 Analytical methods Method assumptions basically about geometry, homogenous layer, modelling. There are some advantages in compare with the empirical method.
Taking into account the parameters that may affect surface movement such as ground conditions, construction techniques, etc. Some author presented issue included: Verruijt & Booker’s method (1996), Loganathan & Poulos’s method (1998) and Bobet’s method (2001). Some assessment about methods: (i) Verruijt and Booker (1996)’s method The result of surface settlement shape from Verrujit and Booker's method was not well fit with the observed settlement profile. (ii) Loganathan and Poulos (1998)’s method It was over predicted for tunnel in soft clay.
(iii) Bobet (2001)’s method This method proposed a deep tunnel in dry soil to extend the new solution for ground movement caused by shallow tunnel in a saturated soil.3 Finite element method using software Plaxis 2D Numerical analyses as finite element method (FEM) is the effective in predict and design in geotechnical problem. With bored tunel using TBM method, Plaxis 2D is software was chosen in this thesis. Material types Plaxis using three type materials include: non-porous, drained behavior and undrained behavior Model boundaries: Möller (2006) proposed boundaries for 2D FEM as follow: Bottom boundary (from tunnel invert to bottom boundary): h (1.2) for D = 4 m ÷ 12 m 13 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com Mesh width (from tunnel center line to vertical mesh boundary): W=2D (1 + ) Where C/D is ratio of cover depth and diameter of tunnel Constitutive model There are some constitutive models which each method could be more exactly results for corresponding condition. Two most popularly constitutive models for TBM projects are the Mohr-Coulomb and Hardening Soil model.
(i) Mohr-Coulomb model (MCM) The Mohr-Coulomb model have well known as the linear elastic perfectly plastic model. The Mohr-Coulomb soil model is used for modeling the behavior of most soils. Soil parameters in this model such as shear strength (c, φ), Young’s modulus (Eref) and Poisson ratio (υ) which are familiar to most geotechnical engineering. In this thesis, the Young modulus Eref is assume no change and liner.
(ii) Hardening Soil model (HSM) The HSM could be considered better than the MCM. HSM proposed by Duncan & Chang (1970), but using plasticity theory not like MCM with elasticity theory. In HSM, the strength parameters can be used from the Mohr Coulomb Model including c, φ. The stiffness of the model included in Eref50, Erefode, Erefur and m.
Modelling segmental lining of tunnel Plate element based on linear plastic material model often uses to model the segmental lining in Plaxis 2D. The equivalent thickness for plate can calculate from this equation: deq= 12 Wood (1975) address the effective moment of inertia as follow: Ie=Ij+( ) I In which, where Ij is the moment of inertia of the joints, I is the moment of inertia of the ring, n is the number of joints in the ring (n > 4). 14 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com CHAPTER 3 METHODOLOGY 3.1 General DEFINITION OBJECTIVE LITERATURE REVIEW METHODOLOGY COLLECTION DATA FOR ANALYSIS GROUT MOVEMENT FINITE ELEMENT EMPIRICAL METHOD METHOD COMPARE PREDICT RESULT WITH MONITORING IN CASE STUDY DISCUSSION, CONLUSION AND RECOMMENDATION Figure 3.1 Flow chart for methodology This chapter aims to describe the methodology to achieve these objectives study. The study also consists of a comparison to the data collection from case study, the description 15 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com of empirical method and numerical method.2 Project case study The proposed Ho Chi Minh City Urban Railway Construction Project (Line1) – Contract Package (CP) 1b is approximately 1.75km long and includes following items: - Two underground station: Opera House Station and Ba Son Station - Twin bored tunnels (780 m) Cut and Cover (C&C) tunnels (530 m) CP-1b interfaces with CP-1a at the South-West boundary and Contract Package 2 at the North-East boundary.
As Contract Package 2 is elevated, the C&C box tunnels transition to tracks on embankment via U-shaped structure. The twin bored tunnels run between Opera House station and Ba Son station. The interface with CP-1a is at the outer face of Opera House station end wall. The subway tunnels run along a corridor in the central urban area of Ho Chi Minh City from a proposed station at the Opera House to a proposed station at the Ba Son shipyard and cut & cover area.
Within this corridor, the project may impact nearby and adjacent structures and buried utilities from bored tunel and excavation works. The extent of bored tunnel section The case study of study is 1.56 km underground tunnel using TBM with equipment of EPB type. The shield tunnels included in 2 bound base on direction East (EB) and West - Bound (WB) tunnel for two pipeline from Opera House Station (CH 0+805) to Ba Son 16 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com Station (CH 1+586), were drilling as figure 3. The main contractor is Shimizu Maeda Joint venture Operation.1 Main properties of Tunnel in HCM MRT line1 Table 3.1 Main properties of bored tunnels Tunnel type Bored tunnel Tunnel length (m) 780mx2 tunnels= 1560m Segment Type 5 standard length segment plus 1 key segment lining Outer diameter 6.2 Main parameters of the EPB shield machine EPB shield parameters Description Route Ba Son – Opera House EPB Machine Manufacturer JTSC Shield diameter 6.