Truck Impact on Buried Water Pipes in Interdependent Water and Road Infrastructures

In the development of sustainable and resilient infrastructures to adapt to the rapidly changing natural and social environment, the complexity of the dependencies and interdependencies within critical infrastructure systems need to be fully understood, as they affect various components of risk and lead to cascading failures. Water and road infrastructures are highly co-located but often managed and maintained separately. One important aspect of their interdependence is the impact of vehicle loading on a road on underlying water pipes. The existing studies lack a comprehensive evaluation of this subject and do not consider possible critical failure scenarios. This study constructed finite element models to analyze the responses of buried water pipes to vehicle loads under an array of scenarios, including various loads, pipe materials, pipe dimensions, and possible extreme conditions, such as corrosion in pipes and a sinkhole under the pipe. The results showed negligible impact of heavy trucks on buried water pipes. The pipe deflection under a maximum allowable truck load in the worst condition was still within the allowable range specified in standards such as those from the American Water Works Association. This implies that the impact of heavy vehicles on water pipes may not need to be considered in the context of the interdependency between water and road infrastructures, which leads to a more unidirectional dependency between these two infrastructures.

Comparison Of Uncertainty Methods For Pipe Deflection Calculation

<p>Reliability of pipe structure is one aspect to be considered in reactor safety analysis. MSC NASTRAN is a computer code that can be used to calculate pipe deflection for reliability evaluation. MSC PATRAN can be used to generate input for this code. Uncertainty evaluation needs to be done in the input variable to understand uncertainty range in the analysis results. A computer code for evaluating structure reliability has been developed in our previous study. The code has implemented latin hypercube sampling (LHS) to assess uncertainty in the input variable, such as load and modulus of elasticity. In this study, comparison of two uncertainty methods, i.e. simple random sampling (SRS) and LHS, was carried out for the developed software. The comparison was subjected to pipe deflection calculation using 100 samples. Comparison analysis shows that LHS method produces a robust mean of variance for all sample size. The results also confirm that variance of pipe deflection using LHS is smaller by 3% than SRS one. It can be concluded that LHS is appropriate to be implemented for uncertainty analysis in the developed code.</p><p><strong> </strong></p>

Numerical Modeling of Pipe-Soil Interaction Under Transverse Direction

Based on the Winkler method, a pipe can be treated as a beam, and pipe-soil interactions can be represented by soil springs in the axial, horizontal and vertical directions. Pipe deflection and resultant forces are correlated by coefficient K in the equation F=Kδ, where F is the resultant force and δ is the pipe displacement. This paper studies pipe-soil interaction for pipelines buried in clay and sand subjected to displacements in oblique directions. The objective is to measure the effect of soil parameters on coefficient K as well as the maximum soil resistance. Pipe-soil behavior has been studied using the finite element software ABAQUS/CAE. There are 48 models in total with varying soil parameters, pipe burial depth and pipe-soil interaction friction for the investigation of the effect of each variable on pipe-soil behavior. In addition, the finite element results have been compared to the analytical results from American Lifelines Alliance guideline (ALA, 2001) and proposed failure envelopes in previous studies.

The Influence of the Twin-Parallel-Tunnels Passing through Construction on Buried Oil & Gas Pipeline

To South-to-north water transfer project as the background, and based on the Peck formula, this paper educes the formula of settlement and internal force which caused by disturbance of the tunnel of the buried pipeline. Considering the different depths of the buried pipelines, the different diameter of the tunnel, the spacing interval between different tunnels and the depth of different tunnels and so on, this paper analyzes the effect of the twin-parallel-tunnels passing through construction on buried oil & gas pipeline. The research shows that the tunnel diameter has no effect on the width of surface subsider and the deflection of buried oil & gas pipelines, but it has great influence on pipeline internal forces. The spacing interval of tunnel has almost no influence on pipe deflection but has effect on the maximum internal force. Different depths of the tunnel contributes much to the rule of pipeline settlement and the distribution of internal forces, and it has greater influence on the internal force than on the pipe deflection . The relationship between the effect and the depth of the tunnels is non-linear. With the tunnel depth increasing, the hazardous conditions of the pipelines show significant improvement.

Safety Investigation of Buried Polyethylene Pipe Subject to Seismic Landslide

As polyethylene (PE) pipes are widely used in the gas transportation system nowadays, increasing attention is attached to the safety of buried PE pipe under seismic load. In this paper, the related failure criterion is proposed and mechanical behavior of PE pipe subject to seismic landslide is investigated. Based on extensive tensile tests, an appropriate constitutive model of PE is selected and the parameters are estimated to simulate mechanical behavior of PE pipes using finite element method. The pipe is assumed to be loaded with a quartic polynomial bending deflection displacement along the axial direction and the soil acts linear elastic. From the numerical simulation results, it is concluded that cross-section deformation is the governing failure mode of buried PE pipe subject to seismic landslide and the critical pipe deflection is about 0.048. Failure criterion curves of seismic landslide are put forward with the combination of failure criterion and engineering practice. The proposed failure criterion curves serve as a foundation available not only for the safety design and assessment also for engineering acceptance criterion of the failure of PE pipe due to seismic landslide.