Vibration control of a tunnel boring machine using adaptive magnetorheological damper

With a large number of tunnel boring machines (TBM) being used in various tunnel constructions, the vibration problem under complex geological conditions have become increasingly prominent. In order to solve the problem, this article investigates the application of an adaptive magnetorheological (MR) damper on the vibration reduction of a TBM. The MR damper could reduce the horizontal vibration of the TBM system and adjust its dragging force on the propulsive system under different geological conditions. The MR damper can also provide large enough damping force even under a small amplitude vibration, which is required by TBM. In this paper, an MR damper was designed, prototyped and its properties were tested by an MTS system, including its current-dependency, amplitude-dependency and frequency-dependency features. A scaled TBM system incorporated with the MR damper was built to evaluate the vibration reduction effectiveness of the MR damper on the TBM system. The experimental test results demonstrate that the displacement and the acceleration amplitudes of the TMB vibration could be reduced by 52.14% and 53.31%, respectively

Theory and Practice of Tunnel Engineering

Tunnel construction is expensive when compared to the construction of other engineering structures. As such, there is always the need to develop more sophisticated and effective methods of construction. There are many long and large tunnels with various purposes in the world, especially for highways, railways, water conveyance, and energy production. Tunnels can be designed effectively by means of two and three-dimensional numerical models. Ground–structure interaction is one of the significant factors acting on economic and safe design. This book presents recent data on tunnel engineering to improve the theory and practice of the construction of underground structures. It provides an overview of tunneling technology and includes chapters that address analytical and numerical methods for rock load estimation and design support systems and advances in measurement systems for underground structures. The book discusses the empirical, analytical, and numerical methods of tunneling practice worldwide

The effect of tunnel construction on future underground railway vibrations

This paper investigates the effect of initial tunnel construction on the future ground vibration levels generated during underground railway line operation. This is important because tunnel construction results in soil disturbance, thus inducing high soil strain levels near the tunnel lining. The resulting soil stiffness degradation impacts the future generation of ground-borne traffic vibration and it's propagation to the foundations of nearby buildings, however has never been investigated. Therefore, to address this, this work develops a novel hybrid modelling approach, consisting of a construction simulation model and an elastodynamics model. First the convergence-confinement method is used to determine the stress state induced during tunnel construction using a tunnel boring machine (TBM). Next a 2.5D FEM-PML model consisting of vehicle-track-tunnel-soil is used to predict the vibration fields induced by underground trains. To link the approaches, the soil stiffness degradation contours computed from the tunnelling simulation act as inputs for the 2.5D underground railway model. This facilitates the assessment of the effect of tunnel construction on vibration levels. It is found that railway ground-borne vibration levels are underestimated if construction effects are ignored, with discrepancies of up to 10 dB found at higher frequencies. Therefore, when estimating future vibration levels during the underground railway design stage (e.g. for subway, metro, high-speed lines … etc), tunnel construction should be considered as an operational source of uncertainty

A review on the buried pipeline responses to tunneling-induced ground settlements

The expansion of cities and urban areas has resulted in an increased demand for environmental and economic transport and services infrastructure. Tunneling, as one of mankind's engineering underground constructions, is taking place close to buried and surface structures such as gas, water, and wastewater pipelines. This paper reviews soil-pipe interaction behavior, tunneling-induced ground settlement, governing equations of soil-pipe settlement, the effects of tunnel depth, size, soil relative density, and volume loss on vertical and horizontal displacement, settlement, shear strain, dilation, pipe bending, and gap formation. A comprehensive literature review, analysis of published papers, and investigations were conducted to study the effect of various parameters on pipeline behavior. The results were obtained by studying the effect of tunneling on ground and pipeline settlement, soil-pipe interaction mechanism, and centrifuge physical modeling. The achieved results of investigations show that the settlement profile follows a Gaussian curve with a wider settlement trough in clay compared to sand. When the tunnel and pipeline are perpendicular to each other, maximum bending strain in the pipeline occurs and the pipeline settlement is symmetrical. The friction effect and formation of contraction and expansion zones lead to the difference between soil volume loss near the surface and tunnel volume loss. When the pipe-soil relative stiffness increases, the pipe bending is less than the maximum soil bending. Also, ground settlement, shear strain, pipeline displacement, and pipeline bending are greater in flexible pipes than in rigid pipelines. This is due to the low resistance of flexible pipelines against bending and settlement caused by tunnel excavation. Positive pipeline bending (downward) occurs near the tunnel axis, which is marked by sagging, but negative bending (upward) occurs at a distance from the tunnel axis, which is known as hogging.  In twin tunnels, by increasing the tunnel spacing the pipeline settlement profile changes from a V-shape to a U-shape and finally a W-shape. Understanding soil-pipe interaction behavior, tunneling-induced ground settlement, and the effects of different parameters on displacement, strain field, settlement, pipe bending, and gap formation beneath pipelines is crucial for engineers evaluating pipeline behavior. Additionally, comprehending these issues can help designers make informed decisions during tunnel construction