Culvert Wall Research Articles

Arching mechanism for large span flexible culverts with shallow soil covers

Soil-steel composite bridges (SSCBs) use the surrounding soil and the culvert’s flexible corrugated steel thin plates to support vertical loads above the culvert. Existing codes use empirical equations based on field measurements and full-scale tests for small and ordinary span SSCBs to estimate the arching process and how it distributes vertical stresses on the culvert walls. The empirical equations then compute the design straining actions. Recent developments in construction technology and urbanization have led to a significant increase in typical spans of SSCBs. This paper investigates large span SSCBs and the associated induced arching action using three-dimensional finite element analysis (FEA). The study compares the FEA findings of straining actions for large span SSCB case studies to the calculations of valid design codes. The comparison demonstrates that existing codes fail to predict the real arching mechanism and, consequently, the resulting straining actions. In addition, the FEA results illustrate how the arching mechanism varies as the span changes. Arching action is typically positive for relatively small spans but becomes negative as the span increases. Finally, results prove that current codes cannot accurately predict real arching, leading to inappropriate design straining actions. For large span SSCBs, these codes require modifications for the arching factors and the profile aspect ratio factors.

Hydraulic parameters of well of Pskom hydroelectric power plant in Uzbekistan

In arid regions, the construction of hydraulic structures is relevant due to the shortage of water resources. Using the example of the Pskov hydroelectric power station, the results of the hydraulic calculation of the end structure of the energy spillway, made in the form of a water well of a unique design, are presented. A culvert wall, made with an initial expanding part and a sloping spillway part forming an oblique spillway, forms the well. The depths and speeds in each part of the water well and the parameters of the hydraulic jump are calculated. It is shown how significant damping of the water flow energy occurs in the selected water well design. The water velocity at the outlet of the water well becomes less eroded, decreasing several times. The critical depth is calculated when the width of the stream changes, the depth of water in the waterhole, the pressure on the waterhole wall, the height of the waterhole wall located along the spillway face of variable width, the interface of the water flows behind the waterhole wall.

Numerical Modelling of Induced Stresses in Buried Corrugated Metal Structures due to Compaction Efforts

An essential element of composite soil-structure pipe and/or culvert systems is the backfilling process, where compaction efforts are applied to newly placed soil layers surrounding flexible corrugated metal pipes/culverts (CMPs/CMCs). Compaction of the layers of the side backfill has a significant effect on the culvert wall response, based on the relative stiffness of the buried structure and the backfill soil material. In the literature, various compaction modelling procedures are described which compute lateral stresses induced in flexible buried culverts due to the backfill compaction. However, a disadvantage of many of these procedures is the simulation of the soil material as an elastic medium, since this results in rebound behavior following removal of the compaction loads. This paper investigates several procedures for applying compaction efforts in two-dimensional finite element analyses (FEA). New numerical modelling procedures are proposed to simulate the effect of soil compaction on buried culverts, including modifications to existing modelling procedures to improve their ability to capture the culvert response. The numerical modelling results are compared with the results of three full-scale tests of buried corrugated metal structures. These structures include an arch pipe and an open-bottom arch culvert in Sweden and a horizontal ellipse pipe in Canada. Based on the analyses, this study concludes that the most effective methods for applying compaction are the use of a vertical surface loading procedure or a prescribed vertical displacement procedure. These procedures provide the best fit with the deformation and the bending moment measurements recorded in the field.

Analysis and Load Rating of Corrugated Steel Arch Culverts

ABSTRACTCulverts are typically used as short span bridge substitutes for spans less 50 ft (15 m). The corrugated metal arch culvert (CMAC) is one of the most popular types, which is frequently installed under highways, airport pavements and railroad tracks. For the purpose of validating the service conditions of CMAC, a load rating method is developed in this study based on AASHTO Manual for Bridge Evaluation. The rating factors (RFs) for culverts are derived to verify the capacity of the culverts to carry current standard truck loads. In order to carry out the load rating, a finite element model of the CMAC is developed for analysing the axial thrust of the culvert wall when subjected to static and dynamic moving truck loads. A method to calculate the CMAC wall thrust capacity is derived by summarizing existing capacity calculation approaches for arch culvert and corrugated metal plates.

The Use of Box Culvert Precast as a Main Bridge Structure in Arterial Highway Road: An Analysis Study

A bridge is a construction that connect two parts of the road cuts off by both natural and artificial obstacles. Meanwhile, a box culvert is a rectangular precast concrete structure that has a basic function as underground construction in the form of culverts, drains, and other supporting constructions. Those function of the box culvert is now developing as the main structure in the construction of bridges and highways. Thus, a research and evaluation should be done. The performance of the existing box culvert structures is in accordance with SNI 1725: 2016 regulations. The research methodology is done by manual calculation to get the load and reinforcement needs, while for static analysis by modelling the structure in SAP 2000 V.14.2.5 program. The material used is the existing material for top-bottom box culvert type (4000 x 4000 x 1500) fc '= 30 MPa and fy = 400 MPa. The results shows the reinforcement does not meet the minimum requirements of strong box structure reinforcement against bridge construction loads. The reinforcement ratio in plate slab area are almost close to the maximum ratio of reinforcement requirements. Whereas in the box culvert wall area, there is an over-reinforcement so the dimensions must be increased.

Utilising the boundary layer to help restore the connectivity of fish habitats and populations

Culverts are a major cause of habitat fragmentation in freshwater ecosystems, are a barrier to fish movement, and can be regarded as a significant contributor in the decline of freshwater fish populations globally. To try to address this, various culvert remediation designs have been implemented, including the installation of vertical baffles and the provision of naturalistic (rock) substrates. While remediation strategies generally aim to reduce the velocity of water flowing through the structure, there is often resistance to their use because the resultant reduction in culvert discharge can negatively impact upstream flooding while also resulting in debris clogging and increased culvert maintenance costs. In addition, baffles markedly increase water turbulence that may be detrimental to passage by some fish species or size classes. Here we present some novel remediation designs that exploit the reduced water velocity in boundary layers along the culvert wall to enhance fish passage without significantly compromising discharge capacity. These longitudinal designs produce an expanded reduced velocity zone along the culvert margins that generate minimal turbulence. We show that these novel designs are significantly advantageous to the swimming endurance and traversability for six small-bodied Australian fish species. We also provide data on how and why some culvert baffle designs may impede small-bodied fish passage. This data scales with increasing water velocity, encompassing inter-specific differences in swimming capacity. These results have broad implications for the movement of small-bodied fish species, and the successful recruitment of large-bodied commercially important species, where baffles have been implemented.

Finite-Element Modeling and Analysis of Early-Age Cracking Risk of Cast-In-Place Concrete Culverts

Extensive cracking was found in several cast-in-place concrete culverts in Alabama. This condition can decrease the long-term durability of the culverts. Early-age stress development in concrete is influenced by temperature changes, modulus of elasticity, stress relaxation, shrinkage, thermal coefficient of expansion, and the degree of restraint. The objective of this study is to determine means to mitigate early-age cracking in culverts by evaluating the cracking risk. Finite-element analysis was used to model the early-age stress by accounting for the following factors: construction sequencing, support restraint, concrete constituents, temperature effects, and the time-dependent development of mechanical properties, creep/relaxation, and drying shrinkage. Experimental results from restraint to volume change tests with rigid cracking frames were used to verify the accuracy of the finite-element analysis. A parametric study was performed to quantify the effect of changing joint spacing, joint type, construction sequence, concrete coefficient of thermal expansion, placement season, and concrete type on the risk of early-age cracking. The finite-element model results revealed that the use of the following measures will reduce the risk of early-age cracking in cast-in-place concrete culverts: concrete with lower coefficient of thermal expansion, contraction joints, sand-lightweight concrete or all-lightweight concrete, and scheduling the casting of the culvert wall to minimize the difference in its placement time relative to its previously cast base. Alternatively, to minimize the contribution of thermal effects on risk of cracking, the construction schedule should be developed to avoid concrete placement during hot weather conditions.

Improved Load Rating of Reinforced-Concrete Box Culverts Using Depth-Calibrated Live-Load Attenuation

This paper describes depth-calibrated live-load attenuation for the load rating of reinforced-concrete box culverts using production-simplified models. In-plane depth calibration is accomplished using a production-simplified, two-dimensional, linear-elastic, finite-element, soil-structure interaction model with results compared with those from the recommended direct-stiffness, structural-frame model. Out-of-plane live-load attenuation considers each potential critical section depth rather than the cover soil depth only. The effectiveness of depth calibration is assessed by comparing predicted live-load moments obtained from the models versus measured live-load moments obtained from full-scale culvert load tests. A load rating case study illustrates the potential for improved alignment between load rating and observed performance. Findings show that depth calibration improves current load rating practice by increasing the accuracy and precision of live-load demand predictions, particularly in culvert walls and bottom slabs. Use of the depth-calibrated soil-structure model helps close the disconnect between calculated load rating and observed structural performance by more accurately predicting both the location of the weakest critical section and the live-load magnitude. The depth-calibrated soil-structure model also moves the predicted live load toward more uniform accuracy and precision across all sections.

Seismic soil–culvert interaction

Box culverts may be constructed in active seismic areas, where ground shaking or ground failures can impose considerable earth pressures on them. In this study, the seismic response of box culverts was investigated experimentally and numerically. A series of scaled centrifuge tests was performed and subjected to three different earthquake signals, with different amplitudes and frequencies. Two values of culvert wall thickness and two values of sand relative density were considered in the experimental program. Experimental results are presented in terms of comparisons of seismic bending moments. These results were used to calibrate and verify two-dimensional numerical models developed using the computer program FLAC. The verified models were then used to investigate the effect of earthquake intensity and frequency, height of soil cover, and culvert thickness on the seismic bending moments for the different culvert sections. Based on the analysis results, charts are presented to aid in the seismic design of box culverts.

Forensic Investigation of Deteriorated Concrete in Plantation East Culverts, City of Benbrook, Texas

Two underground concrete box culverts were installed below ground on Plantation Drive in the City of Benbrook, Texas, in 1991. The culverts consisted of precast segments with case-in-place (CIP) collars/bends. The concrete started deteriorating and spalling at several CIP bend locations as early as 1993. The concrete continued to deteriorate over the subsequent years. An investigation was launched herein to determine the cause and extent of the concrete degradation. The geotechnical investigation involved resistivity imaging, soil boring, and photo-ionic detection for exploring any soil contamination around the culverts that may enhance the concrete deterioration. Visual inspection of the deteriorated concrete helped to examine the clear concrete cover. Concrete cores were taken and tested for strength and deterioration. No soil contamination was observed at the site. The culvert water acidity was neutral. Therefore, the contamination in the underground tunnel/box culvert may not be related to the soil contamination or leakage from sewerage pipes around the culvert areas. The collected concrete core inspection and testing showed that most of the bend concrete is badly deteriorated. Although the strength of some of the more intact bends is acceptable, most of the bend concrete simply does not have sufficient strength, integrity, and ductility to effectively carry the service loads imparted on them. The rebars inside the cores were extensively deteriorated and lost much of their strengths and ductility. The visual inspection showed that the insufficient clear covers were used in the culvert wall and the slab; this was the likely cause of the premature concrete deterioration. On the basis of the investigation performed herein, immediate rehabilitation steps were recommended.

Load-Rating Procedures and Performance Evaluation of Metal Culverts

Load-rating factors are used to evaluate the service life or safety of culverts based on the culvert wall strength and soil cover depth over the culvert. Current culvert load-rating methods have deficiencies in identifying potential critical conditions of corrugated metal culverts. Current load-rating procedures do not provide explicit guidance to the engineer for load rating and evaluation of culvert condition. To ensure good performance over the design life, corrugated metal culverts must be designed and regularly evaluated using an effective load-rating method. The main objective of this study was to investigate the effectiveness of current load-rating procedures. Recommendations are made to improve the analysis and evaluation procedures for corrugated metal culverts. The proposed load-rating procedure is based on an extensive review of load-rating procedures and design practices, experimental data, and theoretical investigations. The proposed method does not include a rating factor for cover depth. However, the design cover depth is required to be checked during the initial design stage to ensure structural stability. New capacity reduction factors are introduced for culvert wall and seam, which require different appraisals for wall and seam during annual inspections. The effect of external live loads is not included in the proposed load-rating procedure for deep culverts and for culverts subjected to low live load stresses. Field data from 39 in-service culverts showed that the proposed load-rating procedure is effective in evaluation of the existing condition of culverts.

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 3.23m(10.6ft)to7.04m(23.1ft) and backfill soil heights over the crown varying from 0.27m(0.9ft)to7.47m(24.5ft). 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 8km∕h(5mi∕h)to64km∕h(40mi∕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 4m(13ft). 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.

The use of recycled tire chips to minimize dynamic earth pressure during compaction of backfill

The backfill areas of concrete culverts constructed in roads have been subjected to differential settlement due to poorly compacted soils. Dynamic compaction rollers cannot be fully utilized to compact the backfill soils near the culverts because the high earth pressure induced by dynamic loading frequently results in cracks in the culvert walls. In this study, two cushion materials, recycled tire chips and expanded polystyrene (EPS) boards are applied on the culvert walls in backfill areas to reduce the dynamic earth pressure induced by the compaction loading as well as to improve the characteristics of compacted soils. A numerical analysis is carried out to study the effects of the cushion materials on the stress variation with soil depth in the backfill areas. The numerical analysis shows that a cushion material with low elastic modulus and high damping ratio can effectively reduce the dynamic earth pressure. Field tests are also performed to study the performance of the two cushion materials. It is found from the field tests that the both cushion materials reduce the dynamic earth pressure acting on the culvert wall. However, the recycled tire chips are more efficient in reducing the dynamic earth pressure because of its relatively high damping ratio and low stiffness values compared to the EPS.

Effectiveness of Strobe Lights for Reducing Juvenile Salmonid Entrainment into a Navigation Lock

AbstractStrobe lights effectively reduced fish entrainment into the large locks at the Hiram M. Chittenden Locks Project in Seattle, Washington. The anadromous salmonids of the Lake Washington system, Chinook salmon Oncorhynchus tshawytscha, coho salmon O. kisutch, sockeye salmon O. nerka, and steelhead O. mykiss, must pass through these locks en route to the Pacific Ocean. Of the available downstream passage routes, use of the large lock‐filling culverts is considered the most harmful to fish because of potential entrainment contact with the barnacle‐lined culvert walls. We evaluated the effectiveness of strobe lights for displacing fish from in front of the culverts and for reducing entrainment during large lock fills. From 3 May to 14 June 2002, we used split‐beam hydroacoustics to estimate the number of fish entrained during paired light‐on‐light‐off treatments. Results indicated that strobe lights significantly reduced (75%) entrainment, an estimated 1,427 fish being entrained during lights‐off treatments versus 350 during lights‐on. Effectiveness was also supported by t‐tests on individual range strata in front of the culvert entrances: 1‐m strata from the floor to 4 m above the floor indicated significant reduction in number of entrained fish during the lights‐on treatments. Using strobe lights for reducing culvert entrainment probably increases juvenile salmonid survival through the locks.

Red River U-Frame Lock No. 1 Backfill-Structure-Foundation Interaction

Using the backfill placement method of analysis, the authors were able to use a limited amount of data on soil properties and limited instrumentation readings to estimate lock performance from initial construction through major flood events, including siltation. Results of the complete soil-structure-foundation interaction analyses for four operational load cases were critical in interpreting instrumentation measurements. A distinction was made between soil-structure interaction of the compacted sand backfill and the stem walls and the interaction of the compacted sand backfill and the culvert walls. This investigation considered the characterization of the range in magnitudes and distributions of horizontal earth pressure coefficient, Kh, and vertical earth pressure coefficient, Kv, along the stem and culvert walls for each load case. Expressing the effective normal pressure and vertical shear stress along lock walls, in relation to earth pressure coefficients, allowed for the precise recovery of both normal and shear stresses for use in simplified design tools.

A Method for Preventing Thermal Cracking in a Concrete Box Culvert Wall

A Method for Preventing Thermal Cracking in a Concrete Box Culvert Wall

Long‐Term Behavior of Buried Large‐Span Culverts

A study is reported on the modeling of large‐span flexible corrugated culverts in the centrifuge environment with emphasis on simulating the construction sequence and long‐term viscous consolidation behavior in cohesive backfills. First, a fully instrumented prototype was selected, which reported both stresses and strains in the culvert and soil mass both during construction and for the long term. Second, a technique was developed in which placement of soil lifts followed by compaction was carried out in the centrifuge under increased acceleration. Third, correlation between prototype and model deflections, stresses and strains in the culvert wall and the surrounding soil mass was obtained at the end of construction for repetitive tests under various levels of acceleration. Finally, long‐term (four months) correlation of model versus prototype behavior: culvert stresses and soil stress‐strain is reported. It is concluded that centrifuge modeling is both an economical and viable means of studying short‐ an...

WINTERING VANESSA ANTIOPA

This beautiful diurnal–the “Camberwell Beauty” of England, and very inappropriately styled the “Mourning Cloak” by Americans, for is it not clothed in a mantle of imperial purple, fringed with gold lace?–is well known to hybernate. It is occasionallv found in stone piles in the winter, but I think its most common hiding-place is in the culvert walls of our country roads and turnpikes. It requires a cold, moist, dark place, or it will dry up.