Geotechnical aspects of tunnel lining with segmental joint parameters to improve soil surface settlement prediction (original) (raw)
Related papers
Journal of Physics: Conference Series
In a shallow tunnel, tunnel construction will triggers a chain of ground movements, resulting in settlements at the ground surface, which become more significant with the decrease in tunnel depth. Therefore, by considering behaviour of the segment tunnel joints (can affect the integrity of tunnel in both circumference and longitudinal directions), the surface settlement trough were investigated. Initial model of dual segmental tunnel lining was model and validated with laboratory test to gain nonlinear response of segment joint. Then, a soil-tunnel simulation model was developed with various segment joint parametric models for Singapore Circle Line Stage 3 (C852) project. Results showed that with the use of flexible segment joints that allow movement (hinge-nonlinear model) in staggered ring tunnel model, the ground deformation depicted higher resemblance of surface settlement pattern to the field data. Steady state settlement was observed after 10m of cutter head distance.
Assessment on Segment Joint to Improve Soil-Tunnel Interaction
MATEC Web of Conferences, 2018
The bending moment of tunnel lining can be influenced by nonuniform ground pressures and joint eccentricities. Influence of joint interaction that induces flexural moment behaviour in segmental tunnel lining was investigated for the project Circle Line Stage 3 (C852), Serangoon Interchange Station. By considering behaviour of segment joint (which can affects the tunnel circumferential and longitudinal safety in overall), the tunnel lining behaviour and displacement of the ground surrounding the tunnel were evaluated. The segment joint modelling in simplified dual-jointed model and in fully soil-tunnel model were developed to assess the effect of segment joint on the overall tunnel response. Ground deformation or settlement trough at the ground surface resulted from the effect of tunnel construction and interaction between soil, tunnel, segment joints and ring joints was predicted. Results showed that with different use of segment joints give different longitudinal settlement. Hinge-nonlinear model together with separated rings model lead to the highest resemblance of surface settlement pattern to the field data when compare to tie model.
Assessment on tunnel lining to ensure stability in soft ground
IOP Conference Series: Materials Science and Engineering
Soft ground tunnelling describes as additional measures that are needed to be taken as it has been associated with settlement due to changes of stress and strength of the soil induced by tunnelling. Segmental tunnel lining is a structure used to support the ground and to have allowable movement due to soil stress redistribution. The research will be focusing on the type of modelling, structure parameter of the tunnel, pressure upon the tunnel lining and relationship with the induced ground settlement. Tunnel modelling was done in three dimensional (3D) modelling using ABAQUS software; of tunnel as parameter. This paper will discuss the effect of jack forces to the global behavior of the tunnel in order to support the surrounding load, thus be able to handle the tunnel-soil reaction without any visible or critical deformation, so that the tunnel can be used in the stable condition. A stand-alone ring method together with all-in-once method was used to simulate the Singapore MRT Circle Line 3 (CCL3). In the findings, when the tunnel lining thickness is reduced, the settlement of the ground surface is increased. Jack forces is also one of the reason of the tunnel to distort and the effect is more visible on the rings with reduced thickness compared to original thickness of the tunnel lining.
Geotechnical and Geological Engineering, 2019
Tunnels are structures which have vital roles in the development of societies. In the numerical models of underground cavities, such as tunnels, loading due to zone elimination is induced instantaneously in the soil mass, and it might cause a disturbance in the stress state especially around the excavation area. However, this is not compatible with the principles of elastoplastic constitutive models used in soil behavior simulations. Besides, the predicted load on the tunnel liner will be larger than the actual value in this kind of modeling. In other words, it causes the so-called overestimated design. Using an appropriate constitutive model could lead the numerical analyses to accurate results. In this research, loading increment in the simulation of soil behavior is evaluated according to experimental data. Next, a correct way for numerical simulation related to underground excavation is described according to gradually eliminating (incremental) stress around tunnels based on the numerical modeling in the finite-difference code called FLAC. Hence, the effect of releasing the stress on the results is illustrated by the stress paths and deformations around a tunnel. Finally, the installation time of the tunnel liner and its impact on the numerical results are considered based on some experimental and field data. It is concluded that the use of software default in modeling the tunnel issues might lead to extreme oscillations in the stress paths, and it could affect the numerical results. Therefore, it is reasonable to utilize a proper way to release the stress around the excavation area gradually.
INTERNATIONAL SOCIETY FOR SOIL MECHANICS AND GEOTECHNICAL ENGINEERING
A criterion proposed by Instituto de Ingeniería, UNAM (II-UNAM) to perform ground-lining interaction analyses for tunnels, when these are formed by segmented rings and double lining, is described. The criterion can be introduced in the "hybrid" analysis method, which is an iterative procedure between geotechnical and structural numerical modeling, where the convergence in terms of diametrical displacements between both types of modeling allows determining the effective stiffness of the tunnel [1]. The criterion allows calculating loads and mechanical elements for the tunnel lining and checking serviceability limits corresponding to constructive or operative aspects. It is useful in the design stages, for revisions of tunnels that are under construction or for existing tunnels affected by new engineering works. In this paper, it is applied to check the interference of a new deep foundation with an existing tunnel.
Ground Behaviour Around a Tunnel Using Various Soil Models
Electronic Journal of Geotechnical Engineering
Finite Element (FE) analyses are used world widely in geotechnical engineering to obtain the soil displacement caused by tunnelling. The surface settlement induced by tunnelling predicted by FE is known to be wider and shallower than the field measurements particularly for stiff clays with high coefficient of earth pressure at rest, K 0 . It has been recognized that neglecting the non-linearity, anisotropy and three-dimensional effects of the soil model as well as K 0 condition can be the reasons of this discrepancy. Unfortunately, such numerical studies were only limited to the problem in the plane strain condition whereas tunnelling is obviously a three dimensional (3D) problem. This paper compares 3D FE modelling of tunnel constructions in stiff soil of London Clay using non-linear soil model with low and high K 0 regimes. It was found that modelling using isotropic non-linear soil with low value of K 0 gave the best matched-fit data on the observed greenfield surface settlement ...
Mining science and technology, 2018
Addressing urban transport is a very timely matter, especially in the capital Hanoi and Ho Chi Minh City. In order to solve this problem, a solution has been proposed for the construction of overhead tram and subway lines. In fact, when constructing subway lines through historical sites, high population density, many surface structures, etc., the method of open construction is not feasible, it is necessary to use the method Underground construction. These areas are often weak soil, the physical parameters of the soil detrimental to the tunnel construction work; Such as small stickiness, small internal friction angle, high porosity, high permeability coefficient, high water saturation, short shear strength etc. These factors create complex geological conditions in Construction tunnel. With that in mind, the calculation of the selection of the tunnel casing structure is necessary, which is timely.This paper provides a solution to the problem of stress state of multilayer lining suppor...
2D numerical investigation of segmental tunnel lining under seismic loading
Soil Dynamics and Earthquake Engineering, 2015
During an earthquake, the better performance of segmental tunnel lining, compared to the continuous in-cast concrete lining, is generally related to the joints between segments. In order to better understand the influence of the segment joints, their effect on the internal forces induced in tunnel lining simultaneously with the effects of the other influential parameters should be considered. In this work, the segmental joints were simulated by the representative stiffnesses and effects of these characteristics in relation to the other parameters such as the soil-liner interface behavior, number of segments in each ring and thickness of segments on the internal forces induced in structure were investigated. For this purpose, 2D numerical analyses were performed and the results obtained were discussed. Results showed that under the seismic condition, the components that had the most significant role on the internal axial forces induced in the segmental lining were rotational stiffness and axial stiffness of joints. Also the bending moments were more affected by the rotational stiffness. Generally, the radial joint stiffness had a less effect on the induced internal forces. With increase in the number of segments and their thickness, the effect of joint stiffness on the internal forces increases and the design of joints should be given more attention; however, the effects of joint stiffness and frictional behavior at the soil-liner interface on the maximum induced forces are almost independent from each other. Also in a specified joint behavior, by variation in each one of the other parameters including the soil-liner interface condition, number of segments and their thickness, the absolute magnitude of the maximum induced internal forces sometimes change significantly.