Journal of Infrastructure Systems

Trenchless construction of pipes can influence the behavior of the soil mass surrounding the pipe depending on the method of construction. A new method for the analysis of buried pipes, introduced in this paper, is capable of modeling the behavior of the soil surrounding the pipe in a manner that is distinct from the rest of the soil mass. The method is based on Vlasov's variational approach for modeling the behavior of soil-structure interaction problems. Vlasov's concept of using a shape function to represent the rate of change of the displacements in a soil layer is extended to describe the rate of change of displacements in the soil surrounding the buried pipe. The behavior of a buried flexible pipe under the effect of a concentrated load is studied under a range of conditions and compared to finite element analysis and to Burns and Richard's solution. The results show reasonable agreement with the finite element method. The new model, however, can be used with different shape functions to describe closely field or experimental observations of the rate of decay of displacements in the disturbed soil mass around the buried pipe.

In this paper, a simulation model for risk analysis making use of the Monte Carlo technique is devised to incorporate the uncertainty in traffic and revenue forecasts for road investment projects. The risk analysis would give the traffic and revenue forecasts in specified years with a particular probability, or vice versa. These traffic and revenue forecasts and their probability levels will help the authorities or the private sector evaluate road investment projects scientifically and systematically. A case study of the proposed Zhuhai Neilingding Crossing is used to illustrate the application of the risk analysis model. Demand elasticity is also introduced to investigate the effects of different toll charges on traffic demand, together with sensitivity analysis on some of the key variables behind the traffic and revenue forecasts.

The recent developments in multimedia and virtual reality technologies allow water resources to be studied with the realism associated with site investigations and the “what if” analysis capabilities common in simulation systems. The proposed virtual reality water quality management systems relies upon the realistic representation of a watershed in three dimensions and the consideration of graphically based water quality models. The user may fly, walk, and dive in the estuarine basin, manipulate infrastructure systems (including polluters and non-polluting facilities), and visualize the results of those actions in real time and in three dimensions. The interface of this system follows many of the video game guidelines. Indeed, Virtual Tejo, a prototype developed for the Tagus Estuary for illustrative purposes, has been successfully used by several thousand users in a game-like environment. The planned extension of the system to the Internet will provide the ground to test the hypothesis that virtual reality water quality systems can assist decision-makers and facilitate citizen participation in water resources infrastructures planning.

Three aspects of accurate evaluation of structural integrity of truss bridges are presented: indirect damage identification, strength evaluation based on inelastic large deformation shakedown analysis, and residual fatigue life determination in the presence of crack-like flaws. In each case, an example problem is presented to demonstrate the application of the proposed methods. Also, the reliability of the proposed methods is discussed.