Stream Assessment for Multicell Culvert Use

Although culverts have traditionally been an economical means of conveying stream flow at a road crossing, they can hinder fish and wildlife passage in the channel and on the floodplain and can create or augment localized channel instabilities. A possible solution to these problems is to use a multiple-cell arrangement, in which one or more culverts placed in the channel convey all flows up to the dominant discharge and one or more culverts positioned in the floodplain convey overbank flows up to the design discharge. This arrangement results in a reduction of flow concentration through the culvert and a properly functioning floodplain, thereby improving fish and wildlife passage and reducing erosional problems. For this system to function properly, a well-established and active floodplain is required; the multicell system will not perform adequately in an incised channel. In this paper, a method to determine appropriate physical environments for multicell culvert systems, based on stream-channel stability and stage-of-channel evolution, is presented.     

Hydraulics of Multibarrel Culverts under Inlet Control

The hydraulic characteristics of multi- and single-barrel circular culverts were compared in this study. One-, two-, and three-barrel culverts configurations, operating under inlet control, were tested in the laboratory with various approach conditions and barrel spacing (horizontal and vertical). The single-barrel head-discharge relationship was consistent with the average head-discharge relationship of the individual barrels in a multibarrel culvert configuration with a uniform upstream approach flow and uniform invert elevations. For the nonuniform approach flow condition, the single-barrel model overpredicted the average-barrel flow by up to 10%. With the middle barrel installed at a lower elevation than the outside barrels, in submerged flow the single-barrel head discharge relationship was consistent with the outside barrels, but the middle barrel was up to 7% more efficient than the single-barrel discharge. The flow rate variations are attributed, in part, to a reduction in approach flow contraction entering the center culvert in the three-culvert configuration and a nonuniform distribution of intermittently forming surface vortices at the culvert inlets. The results of a state (United States) Department of Transportation survey regarding multiple culvert use are also presented.     

Incipient motion of gravel in a bottomless arch culvert

Incipient motion was investigated for four gravel substrate materials in a bottomless arch culvert and a rectangular flume. Different methods for calculating Shields parameter at incipient motion (θc)based upon local flow parameters were explored. An incipient motion region for bottomless arch culverts in fully turbulent flow was defined with two bounding curves on Shields diagram. The variation of θc as a function of relative roughness was examined. Also, a method that utilizes measured flow velocities to determine stable substrate particle diameters for bottomless arched culverts is presented as an alternative to the Shields diagram.     

Entrance Loss Coefficients and Inlet Control Head–Discharge Relationships for Buried-Invert Culverts

In current practice, entrance loss coefficients and inlet control head–discharge relationships for buried-invert culverts designed for fish passage applications are either ignored or approximated using traditional culvert design data due to a lack of data specific to these alternative culvert geometries. This study experimentally determined entrance loss coefficients and inlet control head–discharge relationships for circular culverts with invert burial depths of 20, 40, and 50% and an elliptical culvert with 50% invert burial depth. In general, the inlet loss coefficients for buried-invert culverts were higher than for traditional culverts of the same cross-sectional shape without invert burial. The influence of approach flow conditions (ponded or channelized) on inlet loss coefficients and inlet control head–discharge relationships was also investigated. This paper outlines the experimental methods used to determine entrance loss coefficients and inlet control head–discharge regression constants relative to these alternative culvert geometries and presents the data relevant to the hydraulic design and evaluation of these culverts.     

Spoiler Baffles in Circular Culverts

In many situations the design of culverts prevents the upstream migration of fish because water velocity in the barrel is greater than that of the natural channel. One way to reduce the water velocity within the culvert is to install spoiler baffles on the base. The current investigation uses a three-dimensional numerical tool to examine the influence of the baffle geometry on flow within culverts of varying diameters. The results indicate that spoiler baffles can reduce velocities in the culvert dramatically. The final choice of design hinges on the need of the fish and the discharge capacity of the culvert.     

Hydraulic Performance Curves for Highway Culverts

This paper presents a versatile two-parameter model describing the hydraulic performance of highway culverts operating under inlet control for both unsubmerged and submerged conditions. Applications show that the model can accurately represent the Federal Highway Administration (FHwA) performance curves (which use four parameters) for a range of culvert types and materials. Laboratory data from an investigation of the hydraulic performance of single- and multiple-barrel low-headwater box culverts are also used, and the resulting model predicts a smaller culvert size as compared with the FHwA equations for a given design discharge. Design recommendations are presented for low-headwater box culverts.     

In-Situ Load Testing of Corrugated Steel Pipe-Arch Culverts

A large number of corrugated metal pipe-arch culverts are located under highways. This study investigates the field performance of four existing pipe-arch culverts under static and dynamic loads. Effects of various parameters were considered in selection of the culverts, including backfill height, loading conditions, age of placement, and culvert geometry. Static loads were applied at ten different locations above each culvert using heavily loaded test trucks. Six dynamic tests were conducted at speeds varying from 8 to 64?km/h. A portable instrumentation frame was installed inside each test culvert to monitor the deflections at five critical locations. During each test, strains were also measured using 14 strain gauges. Test results indicated that culvert response was influenced significantly by the backfill height. Nearly symmetrical deflection patterns were recorded for symmetrical loading about the longitudinal vertical plane through the crown. The maximum static deflections were larger than the maximum dynamic deflections for each culvert.     

Vertical Loads on Concrete Box Culverts under High Embankments

Vertical loads on concrete box culverts under high embankments are examined, where a high embankment is defined herein as one where the height of the fill above the culvert is greater than the width of the culvert. Results from an instrumented culvert are described, with results from pressure cells, strain gages in the wall, and strain gages in the roof showing reasonable agreement. There was strong correlation between the height of fill and the pressure and internal forces in the culvert, suggesting that the soil–structure interaction factor is independent of the H/B ratio. The results of the instrumented culvert were compared to those of other instrumented culverts under high embankments. The measured roof pressures were significantly greater than the pressure due to the soil overburden, with the measured pressures averaging 1.5 times the soil overburden pressure. Although the soil–structure interaction factor recommended by the American Society of Highway and Transportation Officials specification tends to under-predict the loads acting on concrete culverts, a simplified reliability analysis suggests that the Specification provides a sufficient level of safety.     

Inspection and Risk Assessment of Concrete Culverts under Ohio’s Highways

In 2003 the Ohio Department of Transportation (ODOT) implemented a new culvert management program. Simultaneously, a team of researchers from the Ohio Research Institute for Transportation and the Environment (ORITE) and engineers from a private consulting firm conducted a joint study to evaluate the effectiveness of field culvert inspection and rating procedures proposed by the ODOT’s new program and describe the best remedial measures currently available for highway culverts. This paper focuses on the first component and addresses it relative to concrete culverts. The new inspection procedure for concrete culverts was applied at 25 sites. Inspection data were examined to detect common problems existing at concrete culvert sites in Ohio. The field data were also analyzed using statistical software to identify factors that contribute to the degradation of concrete culverts. Despite the limited amount of data, the results indicated that the ODOT approach was basically sound. The final segment of the paper presents a risk assessment method developed by the ORITE researchers. The proposed risk assessment method computes the overall structural health rating for any inspected culvert and recommends a course of action.     

Load Performance of In Situ Corrugated Steel Highway Culverts

This paper presents the results of field performance tests of 39 in-service corrugated steel highway culverts in Ohio. The culverts had span lengths varying from 3.23?m (10.6?ft)?to?7.04?m (23.1?ft) and backfill soil heights over the crown varying from 0.27?m (0.9?ft)?to?7.47?m (24.5?ft). Static and dynamic load tests were conducted by driving heavy trucks across the culverts. Static loads were applied at ten different locations above each culvert. Dynamic load tests were conducted at six truck speeds varying from 8?km/h (5?mi/h)?to?64?km/h (40?mi/h). A portable instrumentation frame was installed inside each test culvert to monitor deflections. Strains on the culvert walls were also measured at 14 locations using strain gauges. Effects of backfill height and loading conditions are investigated. According to the experimental results, a plot of maximum culvert deflection versus backfill height shows a nonlinear relationship. Maximum static load deflections were found to be consistently larger than the maximum dynamic deflections obtained using the same test truck. Deflections were nearly zero for deep culverts with backfill heights exceeding 4?m (13?ft). Maximum deflections correlate more closely to equivalent line loads than to total truck weight. The data also indicate that culvert behavior is more difficult to predict when backfill heights are shallow because other factors, such as culvert age and condition and soil type, likely play a significant role.     

Slip-Lined Culvert Inlet End Treatment Hydraulics

Relined culverts must be able to pass the design flood while meeting the necessary embankment freeboard condition. For inlet and outlet control culvert flow conditions, the discharge capacity of a slip-lined culvert is influenced by the geometry of the inlet end treatment. A number of factors including: reduced inlet flow area, the liner pipe wall roughness, and the inlet end treatment influence the relined culvert discharge capacity relative to the original culvert. To develop a better understanding of the influence of slip-lined culvert inlet end treatment geometry on discharge capacity, four different inlet end treatments associated with a thin-wall projecting host pipe and the segmental-lining culvert rehabilitation technique were evaluated experimentally. Inlet control head-discharge relationship and outlet control entrance loss coefficient trends were evaluated as a function of liner projection distance and liner-to-host pipe transition detail (sudden or tapered). The tapered projecting inlet was as much as 7% more efficient under inlet control and approximately 12% more efficient (entrance loss coefficient reduction) under outlet control, relative to the nontapered projecting inlet condition.     

Quantifying Culvert Exit Loss

According to the Federal Highway Administration’s Hydraulic Design of Highway Culverts (HDS-5) Manual and the Hydrologic Engineering Center River Analysis System (HEC-RAS) Reference Manual, the exit loss associated with a culvert discharging into a downstream channel is equal to the change in culvert and channel velocity heads or a loss coefficient multiplied by the culvert velocity head. For a short culvert, the calculated exit loss often represents the largest single system energy loss component. To investigate the apparent dominance of exit loss in outlet control culvert hydraulics, a laboratory culvert exit loss study was conducted using prototype-scale culverts, with projecting end treatments, discharging into a downstream channel where all of the channel discharge was supplied by the culvert. The experimentally determined exit losses were compared with predicted exit loss values using traditional exit loss equations and the Borda–Carnot minor loss expression, which is traditionally used to quantify energy loss at sudden expansions in pressurized pipe flow. The Borda–Carnot expression proved to be significantly more accurate, relative to traditional methods, for the conditions tested.     

Mathematical and physical modeling studies of molten aluminum flow in a tundish

Quantitative velocity and turbulence measurements that were obtained using laser Doppler velocimetry during the course of the physical modeling of the molten aluminum flow in a tundish are presented. Laser sheet and surface powder visualization techniques were also used to provide qualitative understanding of the complex three-dimensional (3-D) flow regimes encountered in the tundish. The experimental findings are compared to the results obtained by the finite-element computational simulation of the flow, showing favorable agreement between the two approaches. Nonintrusive laser Doppler measurements revealed asymmetric velocity and non-isotropic turbulence field near the nozzle exit. In the vicinity of the nozzle, the interaction of the impinging jet and the inclined walls gives rise to vortex structures. Downstream of the nozzle, two counter-rotating secondary cells diminish in strength. The experiments indicate that the turbulence structure near the bottom of the tundish is isotropic, whereas nonisotropy dominates near the free surface. As flow turns through the bend, a separation region is created. The flow heading into the closed duct is observed to be nonsymmetric.     

Experimental Investigation of Shear Capacity of Precast Reinforced Concrete Box Culverts

This study presents an experimental program to investigate the shear capacity of precast reinforced concrete box culverts. Each culvert was subjected to monotonically increasing load through a 254?mm×508?mm (10?in.×20?in.) load plate in order to simulate the HS20 truckload per AASHTO 2005. Instrumentation included strain gauges, high-resolution laser deflection sensor, and automated data acquisition. Four tests were conducted on 1.22?m×1.22?m×1.22?m (4?ft×4?ft×4?ft) box culverts. The location of the load plate was varied to identify the position, which introduces the maximum shear stresses. Laser sensor data and dial gauge readings were recorded to measure the deflection profile of the box culvert. Strain gauges were placed on the steel reinforcement to measure axial strain at locations of maximum positive and negative bending moments. The test results include reporting the loads at which each crack initiated and propagated. The displacement profile of the top slab from the laser instrumentation output along with the load versus maximum deflection for each culvert is also reported.     

Hydraulic Design of a Longitudinal Culvert for Lock Filling and Emptying Systems

The U.S. Army Corps of Engineers is planning navigation improvements for many projects to meet predicted increases in tow traffic. Some of these improvements include the addition or replacement of the navigation lock. Innovative design and construction techniques are being investigated to try and reduce construction costs as well as operation and maintenance costs. The Corps identified that a savings in lock construction could be achieved if the conventional concrete gravity lock walls with culverts inside them could be replaced with thin walls and longitudinal culverts located inside the chamber. This culvert design was designated the In-Chamber Longitudinal Culvert System (ILCS). An extensive research effort led to the development of the ILCS design. This paper provides a brief summary of the research results and the accompanying design guidance developed for low to medium lift ILCS locks. The guidance includes culvert location; port size, location, and spacing; port extensions; culvert-roof overhang; and wall baffles. Lock chamber performance characteristics, based on acceptable filling and emptying operations determined using a laboratory model, are also presented. The ILCS is a feasible design based on the hydraulic performance determined from the investigation.     

Effect of Wheel Live Load on Shear Behavior of Precast Reinforced Concrete Box Culverts

This study reports on a part of a comprehensive study to evaluate the shear capacity of the precast reinforced concrete box culverts. Six full-scale 2.4?m (8?ft) span box culverts were tested to failure by subjecting each culvert to the AASHTO HS-20 wheel load. The location of the wheel load was varied from the tip of the haunch as a function of the top slab effective depth in order to identify the critical shear location. Each test specimen was loaded incrementally up to failure in which crack initiation and propagation were identified and recorded in each load step. In some specimens the top slab compression distribution steel was precluded during specimen fabrication the effect of which was shown to be insignificant in culvert’s performance experimentally. Even though the test specimens were loaded to introduce shear behavior, it was shown that all the test specimens behaved in flexural mode up to and beyond standard factored live load. The test specimens only experienced shear cracks at loads equivalent to approximately twice of the aforementioned factored load. This study concludes that shear is not the governing behavioral mode for the concrete box culverts, and the live load distribution width equations along with the provisions for shear transfer devices for box culverts reported in the current standard need to be revisited.     

Experimental Study and Numerical Simulation on Concrete Box Culverts in Trenches

Concrete culverts in trenches have been widely used in expressways. Problems frequently take place because of improperly estimated vertical earth pressures on culverts. Different codes have been used in China to estimate the design load on culverts. In this study, a full-scale experiment and FEM simulation were conducted to evaluate the variation of vertical earth pressures and soil arching in backfill and to examine the accuracy of the methods recommended by different design codes including the prevailing Chinese General Code for Design of Highway Bridges and Culverts based on the linear earth pressure theory. The measured vertical earth pressures from the experiment were compared with those from the current theoretical methods. The variations of foundation pressure and settlement were also analyzed. The FEM simulation investigated the key influencing factors on the vertical earth pressures including the height of the embankment fill, the width of the trench, the slope angle of the trench, the dimensions of the culvert, the properties of the backfill, and the elastic modulus of the foundation soil. This research reveals that soil arch formed when the backfill on the culvert reached a certain height, but it was unstable. The coefficient of the vertical earth pressure on the top of the culvert was significantly different from that recommended by the Chinese General Code for Design of Highway Bridges and Culverts.     

Energy Dissipation and Air Entrainment in Stepped Storm Waterway: Experimental Study

For the last three decades, research focused on steep stepped chutes. Few studies considered flat-slope stepped geometries such as stepped storm waterways or culverts. In this study, experiments were conducted in a large, flat stepped chute (θ=3.4°) based upon a Froude similitude. Three basic flow regimes were observed: nappe flow without hydraulic jump, transition flow, and skimming flow. Detailed air–water flow measurements were conducted. The results allow a complete characterization of the air concentration and bubble count rate distributions, as well as an accurate estimate of the rate of energy dissipation. The flow resistance, expressed in terms of a modified friction slope, was found to be about 2.5 times greater than in smooth-chute flow. A comparison between smooth- and stepped-invert flows shows that greater aeration and larger residence times take place in the latter geometry. The result confirms the air–water mass transfer potential of stepped cascades, even for flat slopes (θ<5°).     

Hydraulics of Large Culvert beneath Roman Aqueduct of N?mes

The Romans built ancient culverts beneath roads and aqueducts. The hydraulic operation of a large culvert, built around the 1st century A.D. beneath the N?mes aqueduct, is described. The investigation shows the advanced design of an ancient multicell structure with a large discharge capacity equivalent to about 12 times the aqueduct maximum discharge capacity.     

Network Implementation of the Two-Component Pressure Approach for Transient Flow in Storm Sewers

The two-component pressure approach (TPA) is an alternative to the Preissman slot method (PSM) for modeling highly transient sewer flow, including transitions between free-surface and pressurized conditions. TPA and PSM resolve intralink wave action by discretizing sewers with numerous elements and solving one-dimensional flow equations in contrast to link-node models, such as the popular storm water management model, which resolve only interlink wave action. Here, improvements of TPA are reported to support storm sewer network modeling. These include a source term discretization to preserve stationarity, a wetting and drying scheme, and a local time-stepping scheme to coordinate solution updates across many links and enable coupling to a two-dimensional overland flow model. A unique variant of the Harten, Lax and van Leer (HLL) Riemann solver is also introduced, and a boundary solver is developed to accommodate the wide range of possible flow regimes and transitions. The boundary solver is explicit to facilitate the extension of TPA to large networks and coupling with an overland flow model. Promising results are obtained in a varied set of test problems involving simple sewer networks.