After that, a soil model calibration is completed using the curve matching process. In shield tunnelling, segmental linings are usually utilised. Details of each method are summarised in subsequent sections. The work of Verruijt and Booker , Loganathan and Poulos and Bobet are used extensively in Chapter 8 for the ground movement during the tunnelling works of the Bangkok MRT works. The Modified Cam Clay model, proposed by Wroth et al.

These tends have led to the establishment of simple correlations, as shown in Figures 4. This plot revealed the empirical trends of value i at various tunnel depths with regards to soil type. For this reason, the major aim of the current study presented in this chapter was to conduct an extensive study of the finite element parameters evaluation from conventional laboratory tests i. The results show that the gap parameter used in the plane strain analysis is the most critical governing parameter. The water remains behind this cake.

The corresponding value of 0. Calculate Et using Eq. There is a need in manual shops to Further details of the design aspects for the underground station excavation methods, for the Bangkok Blue Line Extension Project, can be found in Suwansawat et al.

dissertation strain mrt

Two analyses were performed using the proposed model AJ4. Details of each method are summarised in subsequent sections.

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Modeling of a limestone aquifer in the north west of Sri Lanka is attempted. Moreover, all the excess pore pressure plots were located in the positive range. The second one, which is the major part, relates to the interpretation of the oedometer and triaxial deformation parameters for the Hyperbolic and Hardening Soil Model analysis.


Three empirical methods i. As a result, the drained strength parameters should be carefully selected according to the applied stress path, resulting from the construction sequences.

dissertation strain mrt

There is no guidelines available in the Universities to perform the office administration effectively and efficiently.

Wroth asserts that the pressure at the commencement of the unloading and reloading processes pa and pb should be as follow: The best fit HS Model parameters and their resulting predictions are illustrated in Table 4. It was found that all test series have a highly linear relationships which confirmed the Equation 4. The remaining cross sectional area will be excavated later on and again followed by immediate shotcreting.

The tunnel lining is of twin bored single-track tunnels. The OCR in the soft clay layer ranges from 1. Based on the available data, different research methodologies were used to study the behaviour of the Bangkok subsoil during shield tunnelling works, including empirical, analytical and numerical methods. In a similar manner to the triaxial moduli, the oedometer modulus Eoed obeys the stress dependency law: Chapter 4 focused on evaluation of geotechnical parameters from laboratory tests.

Based on the review of the quality of field measurements wall deflections and ground surface settlementsin 18 subway stations, the Sukhumvit Station is selected as the best one to perform a detail 2D finite element analysis using Plaxis. This target face pressure is dependent on the design alignment and subsurface ground conditions. Stiff to Hard Clay A layer of yellowish to light grayish brown, stiff to very stiff or hard clay is present between depths of 15 to 33 m.


The shear strength of rock mass, already reduced by these discontinuities, will further diminish Hence, calculate E50 for all the values of Ei using Eq. In this analysis the Ko of Bangkok Soft Clay was assumed as 0.

Indeed, Hardening Soil model has developed under the framework of the theory of plasticity. When modelling the tunnel excavation process, using a 2D plane strain analysis, some approximate methods, as proposed by the above authors, dissertatio needed to take into account the stress redistribution ahead of the tunnel face.

It should be noted that, Eqs. Therefore, the lateral ground movement is symmetrical about the tunnel axis.

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Instead, their relationships can be expressed as: He concluded that the overall trough width parameter ifor single and twin tunnels, was about m and m, respectively.

In order to advance the shield, it is necessary to excavate an oversize hole using over- cutter or copy cutter.

The dissertatkon of this procedure and the results obtained are explained in the following subsections. The stations are up to m long and approximately 25 m wide, and are excavated up to a depth of 25 to 30 m below the ground surface. Beyond these values of the deviator stress, the samples were each found to have different stress—strain curves.