A three-dimensional tunnel model for calculation of train-induced ground vibration

https://hal.archives-ouvertes.fr/hal-01004923/document

A numerical model for ground-borne vibrations from underground railway traffic based on a periodic finite element–boundary element formulation

https://pure.hw.ac.uk/ws/files/7458259/pre_production.pdf

Numerical modelling of ground borne vibrations from high speed rail lines on embankments

Coupled boundary and finite element analysis of vibration from railway tunnels—a comparison of two- and three-dimensional models

Benchmarking railway vibrations – Track, vehicle, ground and building effects

A model is proposed for finite‐element modeling of tension crack propagation in soils. The essential features of this model are the splitting of a single node into two distinct nodes in the wake of an advancing crack tip to replicate separation of material on either side of the crack, and the use of a fracture mechanics criterion to predict crack propagation. The material parameter employed in this criterion, the critical energy release rate, is determined experimentally and shown to be reasonably constant over a range of crack lengths, thereby supporting the adoption of this parameter as a material constant for tension cracking in soils. The model is then applied to two classes of problems in which tension cracking is known to exercise significant influence, a stiff embankment on soft soil and an excavated slope. For both problems, stable and reasonable solutions are obtained, suggesting that fracture mechanics offers a feasible approach to the analysis of tension cracking in soils.

Tension Crack Development in Soils

The steady‐state vibration of a subway‐soil‐building system is determined using an appropriate finite element model. The vibration level in the podium block of the building is obtained for two different track support systems: direct fixation and a floating slab. A pair of unit harmonic loads is used to simulate the wheel loading from a single train. Because the subway consists of twin double boxes, different loading combinations are used to determine the maximum velocity response in the podium for the frequency range of interest. It is found that the vibration levels for the floating slab track system exceed those of the direct fixation track system in the low frequency range. However, in the high frequency range, the floating slab track system behaves as an effective vibration isolator.

Steady‐State Vibration of Subway‐Soil‐Building System

An analytical procedure is presented for determining groundborne vibrations in buildings due to subway trains. The procedure involves a finite element idealization of the subway-soil-structure interaction problem, using an analytical model for the train loading spectrum at the tunnel invert. Both direct fixation and floating slab track support systems are considered. The train model is verified using the measurements of rail velocities. The proposed procedure is applied to the case of a four-storey podium block enclosing twin double-box subways within the confines of its ribbed wall foundations. The severity of velocity response levels of the building, in relation to vibration standards, is also considered.

Groundborne vibrations due to trains in tunnels

A world-wide review of heavy tamping projects indicated that highly organic clays which due to their secondary compression characteristics may not be amenable to treatment by surcharge and vertical drain installation alone, may nevertheless be stabilized by applying high energy impact on installed dynamic replacement (DR) sand columns using a conventional dynamic consolidation plant. Field trials were thus conducted to enforce primary, as well as to negate secondary, compression of in situ peaty clay deposits by this form of treatment application, in the course of which dynamic replacement and mixing (DRM) of such soils with sand charges was originally identified as a distinct ground-improvement mechanism. From the field results and review, it is also perceived that ground-improvement mechanisms resulting from the application of a wide variety of heavy tamping plant and procedures to soils ranging from granular to highly organic cohesive materials may be generalized on a common physical basis. Further, unique relations may apparently be construed between alternative measures of degree of ground improvement on the one hand, and a collective term incorporating initial soil consistency and standard operational parameters of ground treatment on the other, thereby providing a basis for rational performance design.

Unified Approach to Ground Improvement by Heavy Tamping

It is well established that critical state soil mechanics provides a useful theoretical framework for constitutive modeling of soil. Most of the critical state models, including the popular modified Cam clay (MCC) model, predict soil behavior in the subcritical region fairly well. However, the predictions for heavily overconsolidated soils, in the supercritical region, are not so satisfactory. Furthermore, the critical state models were developed from triaxial test data and extension of these models into three-dimensional (3D) stress space has not been investigated thoroughly. In the present work, experiments were carried out to obtain stress–strain behavior of overconsolidated soil in triaxial compression, extension, and plane strain conditions. A novel biaxial device has been developed to conduct the plane strain tests. The experimental results were used to formulate Hvorslev–MCC model which has MCC features in the subcritical region and Hvorslev surface in the supercritical region. The model was genera...

K. W. Lo

Papers

Tension Crack Development in Soils

Steady‐State Vibration of Subway‐Soil‐Building System

Groundborne vibrations due to trains in tunnels

Unified Approach to Ground Improvement by Heavy Tamping

Performance of a Three-Dimensional Hvorslev–Modified Cam Clay Model for Overconsolidated Clay