Samuel T. Ariaratnam

Application of simulation in trenchless renewal of underground urban infrastructure

Pipe bursting is a type of trenchless technology that enables the construction, rehabilitation, or replacement of underground urban infrastructure with minimal disruption to surface activity. This construction process facilitates the installation of sewer pipes and gas mains of similar or larger diameters at the same location as existing lines. The upsizing capability is particularly relevant in situations where greater flow capacities are required due to increased urbanization. The paper presents an application of a simulation platform developed at the University of Alberta called Simphony, used to create a special purpose simulation application of the pipe bursting process. Results obtained from this model can assist owners, engineers, contractors, and equipment manufacturers in designing and planning pipe bursting projects.

A PARAMETRIC STUDY OF UNDERGROUND UTILITY INFRASTRUCTURE IN CHINA

Rapid economic growth in China has lead to the increase in the installation of underground utility infrastructure across the country. Major international events including the 2008 Olympic Games in Beijing and the 2010 World Expo in Shanghai have spearheaded this growth. As a result, trenchless technology has seen an increase in application due to its minimal impact on the environment, increased productivity, cost effectiveness, and worker safety. For example, there are currently over 5,200 horizontal directional drill rigs in operation from approximately 30 Chinese manufacturers. This paper presents the results of a survey questionnaire distributed to 58 professionals in the underground utility including contractors, designers, manufacturers, agencies, and research institutions. Information on trenchless construction methods utilized, pipe materials, industry sector involvement, origin of equipment, and method for detecting existing underground utilities was solicited. Additionally, influence factors inherent to trenchless construction were quantified based on practitioner sector. Existing utilities and experience of personnel were found to be the most critical factors when assessing an underground utility infrastructure project. These were closely followed by equipment capacity and soil features. Understanding the perception of practitioners should lead to more success underground utility infrastructure projects in China.

Subsurface Ground Movements Associated with Trenchless Pipe Replacement Methods

As we enter the new millenium, our nation is facing a crisis resulting from underground infrastructure that are functioning far beyond any reasonably anticipated design life and require renewal to mitigate deterioration. Maintaining this large network of underground sewer, water, and gas pipelines is difficult and costly. The problem is compounded by the significant impacts that a major repair or rehabilitation project can have on the daily life, traffic, and commerce of the area served by and along the pipeline in question. Trenchless pipe replacement, or pipe bursting, provides a trenchless alternative for the renewal of underground infrastructure. The process includes various static, hydraulic, and pneumatic methods of breaking an existing pipe and simultaneously installing, by pulling or pushing, a new pipe of equal or larger diameter. One of the greatest challenges facing acceptance of this renewal option is the issue of its effects on adjacent buried infrastructure. This paper describes a unique approach for monitoring subsurface ground movements during the pipe bursting process to assist planners and contractors in evaluating the risk of potential damage to surrounding structures. Initial field testing of this procedure on the Millstone Sanitary Trunk Sewer project in the City of Nanaimo, British Columbia is described. It is anticipated that adoption of this trenchless method of urban renewal will increase, as more techniques are developed to quantify the risks associated with soil movements. l Graduate Research Assistant, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada T6G 2G7; tel. (780) 492-8966, fax (780) 492-0249 2 Assistant Professor, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada T6G 2G7; tel (780) 492-5110, fax (780) 492-0249

Application of Digital Photogrammetry in Trenchless Engineering

This paper introduces the application of photogrammetric methods in trenchless engineering applications including construction job site monitoring and three-dimensional underground utility mapping. Accurate three-dimensional representations of buildings, roads, and other utilities on the job site can be easily obtained through the processing of digital photographs using photogrammetric software. This provides an avenue for assisting contractors in quality control of their construction processes. The existence of telecommunication, electrical, cable, water, wastewater, and gas pipelines provide potential strike hazards for trenchless methods such as horizontal directional drilling. Subsequently, it is imperative that accurate as-built maps be generated. This paper demonstrates the use of digital photogrammetric methods through field trail of mapping and monitoring applications.

A novel approach to measuring ground movements associated with trenchless construction techniques

This paper discusses the application of photogrammetric methods to monitor ground movements during trenchless construction projects. Ground movements are a concern as they can cause damage to buried utilities and surface structures. Photogrammetry is a remote sensing technique in which the geometric properties of objects and surfaces can be determined from photographic images. This technique allows for accurate three-dimensional measurements of specific points on the ground surface. Measurements are determined utilizing two or more photographs taken from different positions at specific time intervals. Photographs from specific time intervals are complied using photogrammetry software to determine the position of surface points in three-dimensional space. This paper provides an overview of the photogrammetric method, its application to trenchless projects, and results and analysis of data gathered from calibration and repeatability of measurement studies.

Horizontal sampling: A new direction in site characterization

Traditionally, sampling and monitoring of potentially contaminated soils and ground water has been achieved using vertical drilling technology. However, vertical drilling presents several technical limitations, including the need to position the drilling rig directly above the target zone and the risk of cross-contaminating laterally stacked aquifers. These limitations may be overcome using horizontal directional drilling technology. This paper gives a short introduction to horizontal directional drilling equipment and installation techniques, followed by an overview of existing horizontal sampling tools. Details for the development of a horizontal multiple port soil sampler are outlined and the future role of horizontal sampling in site investigation is discussed. It is concluded that horizontal directional drilling technology has many applications in site investigation, offering an efficient and cost-effective method of collecting geotechnical and geo-environmental data, both as an alternative and as a complement to vertical drilling and sampling technologies.

Assessment Of Emerging Pulled-In-Place Pipe Products For Trenchless Applications

Pulled-in-place pipes for trenchless construction applications have traditionally consisted of Steel and High Density Polyethylene (HDPE) material. While providing excellent documented results, these two materials require professional welding and fusion of their joints prior to installation. New developments have introduced two emerging pipe products that are rapidly gaining acceptance as alternatives to Steel and HDPE. These are Flex-Ring Restrained Joint Ductile Iron and C-900 Polyvinylcholoride (PVC) pipes. Centrifugally cast for transport of water, sewer, or other liquids, the Flex-Ring Ductile Iron pipe allows for up to 5 degree flexing and comes in diameters ranging from 100 mm (4 in.) to 900 mm (36 in.). Additionally, the boltless restrained connection provides flexibility, ease of assembly, and positive restraint against endwise separation due to pulling during trenchless installation. The restrained joint C900 PVC pipe increases the tensile capacity of a standard bell-and-spigot PVC pipe by 35 times, while maintaining the ability to negotiate tight curves (i.e. min. bending radius of 19 m). Typically used in horizontal directional drilling and pipe bursting installations, both pipe products meet AWWA pressure standards making them suitable for pressure pipe applications. This paper provides discussion on these two emerging pulled-in-place products for trenchless applications and analysis of testing results supplemented with supporting field case studies.

Bonding Procedures for North American and International Construction Contracts

AbstractSurety bonding has become essential in todays construction market. The industry is complex, and contractors face high expectations for contract performance. The global construction market and the chance to learn from others justify discussing general bonding procedures and comparing North American and international construction bonding. The main difference is in the type of bonding; the North American construction industry uses an obligatory type rather than the forfeiture type commonly used internationally. Further, there are noticeable differences in bond amounts due to the type of bonding. The procedures used by North American sureties in issuing bonds are more rigid as the surety assumes the entire responsibility of the contract completion whereas bonds are considered an extension of the contractors line of credit in international contracts. The common law implications, surety requirements, premiums, and other concerns are detailed.

NUMERICAL ANALYSIS OF SUBMERGED SOIL BEHAVIOR IN PIPELINE INSTALLATIONS CROSSING RIVERS

The paper investigates the pattern of soil stress around a pipeline installed under the river using a non-linear three-dimensional finite element method (FEM). This study compares von Mises soil stresses occurring in native soil adjacent to river crossing pipeline between traditional open trench (OT) and horizontal directional drilling (HDD) pipe installation methods. The MohrCoulomb theory is utilized to describe soil behavior in the finite element models. The entire model is assumed to be elasto-plastic. The whole research considers saturated native soil in one month after construction. Additionally, design parameters (i.e. depth of cover and annular space) in HDD method are examined for understanding their influence on soil stress occurring around original soil. The paper investigates how critical design parameters (i.e. density and diameter) in the annular space affect the pattern of maximum von Mises soil stresses occurring in native soil adjacent to pipeline installed under the river. Finally this study found that when the OT method is used for pipeline crossing under the river, stress occurring in the soil cover is greater than when the HDD method is used. In addition, the diameter of the annular space in HDD method could impact on total soil stress occurring in the soil overburden.

Prediction of surface heave associated with horizontal drilling using neural networks

This paper presents the implementation of an artificial neural network to predict surface heave resulting from shallow subsurface utility installations conducted with horizontal directional drilling. Data gathered from a full factorial field experimentation examining the effects of drilling techniques is utilized in the network development, with the attempt to understand the relationship between construction techniques and resulting surface heave. The developed model is compared to a multivariate linear regression analysis conducted on the raw data, and a sensitivity analysis utilizing the trained network connection weights is conducted to determine which factor has the greatest effect on surface heave development. Further examination of the behavior of the system is provided through a trend analysis which studied the effect of each drilling factor on the predicted surface heave. The results indicate that a neural network would adequately model the relationship between drilling techniques and the resulting surface heave.