Bridge Foundations Research Articles

3D Numerical Simulation of Sea-cross Bridge Pier Wave Current Force Considering Local Scour Effect

The combined force of wave and current is the key load to the foundation of the sea-cross bridge, which is directly related to the design scale. Local scour pits are quickly formed after the piers enter the water, so the influence of local scour pits on the wave current force should be taken into account. Typical bridge pier structure is selected as the research object by the project of Yushan Bridge. Physical model test was applied to research the wave current force on the current terrain. Through the application of Fluent -3D, the mathematical model was established, and the model was verified by the test results. By using the 3D mathematical model, the wave current force considering the bridge pier local scour was calculated to provide technical support for the design of the bridge.

Analysis of key points of road and bridge foundation construction technology

In the process of road and bridge construction, basic construction technology is most the important. Only when the basic construction technology is improved can the overall quality of the road and bridge be improved. Therefore, the relevant construction units must strengthen the research of basic construction technology and master the technical points to accelerate road and bridge construction. In view of this, this paper mainly analyzes the key points of road and bridge foundation construction technology.

Application Research of Maintenance and Reinforcement Technology for Arch Bridge Foundation

In order to study the application of maintenance and reinforcement technology for arch bridge foundation, taking a reinforced concrete half-through arch bridge and a rigid frame arch bridges as examples, the appearance inspection and disease analysis of the bridge piers and pile foundations were carried out. Based on the modified theoretical calculation model, the analysis method of diseases and the maintenance and reinforcement technology were proposed. The method of the pier section enlargement and adding pile is adopted to strengthen the arch bridge foundation. The results show that according to the modified theoretical calculation model, the actual diseases including the distribution area of cracks and degradation degree are in good agreement with the theoretical calculation results. The reinforcement design of section enlargement and adding pile can provide a reference for the reinforcement of similar arch bridges.

Solutions for Foundation Systems Subjected to Earthquake Conditions

Soil–structure interaction plays an important role in dynamic behaviour of a foundation under combined static and seismic loadings. This paper describes a few case histories with field studies of deeply embedded bridge foundations to showcase the earthquake induced lateral effects using finite element framework. Rigorous dynamic approach with detailed numerical analysis for large diameter pile foundation and pseudo-static approach for rigid caisson foundation presented in this study demonstrated the functionality of foundation systems in seismic conditions. Efficacy of barrettes over piles as a cost-effective foundation solution in high-rise buildings has also been discussed by obtaining higher resistance under static condition. Finally, an analytical methodology considering three-dimensional passive wedge developed in front of the rigid caissons is presented for estimating the ultimate soil resistance under seismic condition. Closed-form expressions to determine seismic passive earth pressure coefficient and its distribution along caisson length for different embedment ratio have been explained here that can be adopted in practice to analyse foundation systems subjected to earthquake condition.

Siesmic Response of Single Pile Soil Structure Interaction Effect of Cordera bridge foundation

The response of single pile foundations to the dynamic loads is considered in this paper. The behaviour of such foundation is important specifically in case of earthquake excitation through the supporting soil medium. An axisymmetric finite element model has been implemented to simulate the behaviour of pile in relatively clayey soil deposit using Abaqus software including the soil structure interaction effect soil system. Eight node axisymmetric quadrilateral element CAX8R used to simulate the soil continuum. Contact behaviour between the single pile part and the part of soil was simulated using the ‘surface to surface’ contact method with master-slave concept. Furthermore, the pile behaviour material has been simulated with a linear elastic model while, soil material has been simulated with an elasto-plastic model “Mohr-Coulomb failure criterion”. Two different excitation have been adopted during the analysis: El-Centro and Ali-Algharbi earthquakes in order to investigate the effect of various intensities. The results of the analysis demonstrate alteration in the relative displacement and stresses along the pile with different soil layer and different stiffness with both earthquake excitations.

Research on Influence of Deep Foundation Pit Excavation and Dewatering on Pile Foundation of Railway Bridge

The three-dimensional numerical model of the foundation pit engineering is established, and the fluid-structure coupling method is used to calculate the settlement of the pile foundation of the adjacent railway bridge caused by the excavation and dewatering of the foundation pit. The results show that the settlement range of the soil around the foundation pit reaches 140m, and the pile foundation of the railway bridge is within the influence range, but the maximum settlement value does not exceed the limit value specified in the design. The method used in this paper provides effective guidance for the construction optimization of the same type of projects and reduces the project cost.

Numerical Simulation Study on Cross Construction of Seawall Engineering and Bridge Foundation

In view of the overlapping project between the double track bridge of Ningbo-Taizhou-Wenzhou expressway and seawall, the large-scale three-dimensional finite element calculation is carried out by using the finite element software ABAQUS, the displacement limit of bridge pier top is studied, the internal force deformation of bridge pile foundation and its variation law in the process of seawall filling and later consolidation settlement are analyzed, and the influence of sea seawall filling on the stress and deformation of bridge pile foundation is studied. The calculation results show that: the main pier in the enclosure side of the two main piers in the design scheme is most affected by the construction of seawall. At the end of seawall construction, the longitudinal displacement along the bridge is 25.56cm, the transverse displacement is -10.68cm, and the settlement is 3.49cm. From the beginning of seawall construction to 15 years after the completion of seawall, the maximum longitudinal displacement along the bridge is -80.87cm, the maximum transverse displacement is -38.94cm, and the maximum settlement is 382.2cm, in which the settlement during the construction period is 346.0cm, accounting for 90.5%. The calculation results of design scheme show that the displacement of bridge pier top is too large, and the tensile stress of bridge pile is also large, therefore, it is necessary to optimize the design scheme to reduce the displacement of the bridge.

Research on Reliability of Straight Thread Connection of Reinforcement Cage of Bridge Foundation

With the continuous improvement of bridge construction technology in our country, although the service life of the bridge has been greatly extended, the mechanical connection technology of steel bar in the technology is still in the stage of steel bar straight thread connection, which is nearly 30 years behind that of foreign countries. According to the development status and application requirements of bridge construction in China, it is of great practical significance to explore new technologies and methods to solve the problem of insufficient strength of straight thread connection of reinforcement. In this paper, the reliability of the straight thread reinforcement connection in the bridge foundation reinforcement cage connection technology is studied as the main breakthrough point, and the main problems encountered in the application of the straight thread reinforcement connection technology in the bridge reinforcement cage connection are analyzed.

Comparison of bearing capacity pile foundation base on pile dynamic analyzer test and conventional analysis (Case on foundation bridge in Cikampek)

The foundation as the base of construction work must be able to bear the structural load from above and carry it down. Thus, the foundation analysis needs to be done for designed and build to determine the stability value of the foundation due to load and deformation. This research will be carried out in two different ways: analyzing PDA test results and calculating the bearing capacity of the foundation using Mayerhoff, Poulos Davis and Tomlinson’s method. Those two different ways will have resulted in a comparison of dynamic analysis. So it can be concluded through the regression results that will be determined in a linear and logarithmically. Based on the Mayerhoff method, bearing capacity regression values linearly ranged from 0.77 to 0.86 while logarithmically is 0.8. For the Paulos Davis method, the linear and logarithmic regression values range between 0.7 to 0.88. The Tomlinson method produces regression values ranging from 0.65 to 0.88 in a linear and logarithmic. This study shows differences in the value of regression from various conventional analyzes that have been carried out.

A method to reduce climate-related risks for transport infrastructure facilities in permafrost regions

Using simulation modeling tools, we estimated the reduction of the risk of functional degradation in a pile foundation of a road bridge in changing climatic conditions. Air warming was considered as a random variable with normal distribution with an average value of +2°C. Climate-related risks normalized to the range of 0–1000 points were estimated by the reduction in the bearing capacity of a pile foundation in changing climatic conditions. To reduce these risks, it was suggested to use seasonal cooling devices (SCDs) making it possible to partially bring soil temperature conditions to the design state. We assessed the efficiency of SCD utilization by the reduction of the risk. For the transport infrastructure facility under consideration, the value totaled 105 points. Thus, the residual climate-related risk, with SCDs being used, is predicted to amount to 333 points. The method suggested allows us to objectively determine whether it is reasonable to take engineering and technical measures to reduce climate-related risks for transport infrastructure.

Deformation modulus of rock foundation in Deriner Arch Dam

Civil engineering structures such as gravity concrete dams, arch dams, pressure tunnels, foundations of high-rise buildings and bridges are generally founded on rock. Design and performance of these structures are highly dependent on the deformation modulus of the rock mass so that expected deformations and/or differential settlements stay within the tolerable limits of the structures. In situ deformation modulus measurements of rock masses are generally performed by using the borehole dilatometer and plate loading tests in Turkey. The diameter of plate loading test device is 30-35 cm. Tests are performed in small unlined tunnels excavated in different elevations of dam abutments. The deformations upon loading are measured on the loading plate in the plate loading tests. It is not possible to exclude the effect of excavation disturbed zone since deformations are not measured with these devices. Large diameter plate test system may have multiple level extensometers set in drill holes opened perpendicular to loading plates. Reading from these extensometers may be utilized to exclude the effect of disturbed zone close to surface together with stress distribution estimated by using elastic theory. There are several field test methods for determining deformation modulus and each method has its own shortcomings. The optimum methodology to correlate plate loading test results with corresponding in-situ deformation modulus values is to back-calculate deformation modulus by using settlements measurements during the construction of dam body. In this paper, Deriner Arch Dam settlements measured during the construction are used to back calculate deformation modulus. It is found that in situ deformation modulus is about two times higher than the average value determined by plate loading tests. This finding will have important effects on the depth of foundation excavations, concrete layers to fortify structure foundations and the amount of consolidation grouting

Effect of slope with overburden layer on the bearing behavior of large-diameter rock-socketed piles

Pile foundation is a typical form of bridge foundation and viaduct, and large-diameter rock-socketed piles are typically adopted in bridges with long span or high piers. To investigate the effect of a mountain slope with a deep overburden layer on the bearing characteristics of large-diameter rock-socketed piles, four centrifuge model tests of single piles on different slopes (0o, 15o, 30o and 45o) were carried out to investigate the effect of slope on the bearing characteristics of piles. In addition, three pile group tests with different slope (0o, 30o and 45o) were also performed to explore the effect of slope on the bearing characteristics of the pile group. The results of the single pile tests indicate that the slope with a deep overburden layer not only accelerates the drag force of the pile with the increasing slope, but also causes the bending moment to move down owing to the increase in the unsymmetrical pressure around the pile. As the slope increases from 0o to 45o, the drag force of the pile is significantly enlarged and the axial force of the pile reduces to beyond 12%. The position of the maximum bending moment of the pile shifts downward, while the magnitude becomes larger. Meanwhile, the slope results in the reduction in the shaft resistance of the pile, and the maximum value at the front side of the pile is 3.98% less than at its rear side at a 45o slope. The load-sharing ratio of the tip resistance of the pile is increased from 5.49% to 12.02%. The results of the pile group tests show that the increase in the slope enhances the uneven distribution of the pile top reaction and yields a larger bending moment and different settlements on the pile cap, which might cause safety issues to bridge structures.

Migration of sand mining pit in rivers: An experimental, numerical and case study

Irregular, unauthorized and non-technical mining of sand and gravel from rivers play an important role in undesirable changes in morphology and environment. The present experimental study investigated sand mining pit modelling in the different scenarios. A two-dimensional flexible mesh, depth averaged model was set-up to simulate the experiments. The results exhibited an acceptable agreement between the numerical and experimental results, so that the maximum error was limited to less than 10%. After verifying the numerical model, a critical reach in Helleh River was selected as a case study. The effect of sand and gravel mining on a bridge at the site was studied. The results also indicated that for a flood event with a return period of 25 years, sand and gravel mining changed the bed profile up to 1.27 m at the bridge foundation. Moreover, initial signs of river meandering emerged in one scenario.

Influence of the Water State on Mechanical Properties of Port Sand

Chen, G.; Wang, Q., and Ma, Y., 2020. Influence of the water state on mechanical properties of port sand. In: Hu, C. and Cai, M. (eds.), Geo-informatics and Oceanography. Journal of Coastal Research, Special Issue No. 105, pp. 190–194. Coconut Creek (Florida), ISSN 0749-0208.With the development of China's economy, the role of marine transportation is gradually strengthened. The foundations of port buildings or transportation bridges comprise soil. The stability of foundation soil seriously affects the stability of coastal buildings. Especially in the northern region, the freezing or melting state of water causes great damage to the port superstructure. In spring, thawing and settlement of that soil will cause structure settlement, even causing cracking and collapse. It is necessary to study the influence of the water state on the engineering properties of foundation soil in port area. This paper takes the port sand as the research object, through the experimental method, performs the freeze-thaw cycle loading to the different gradation port sand with a range of water content, and obtains its shear strength law under various engineering condition. The experimental results and conclusions have reference value for the design and construct of port buildings.

Integral abutment bridges: Investigation of seismic soil‐structure interaction effects by shaking table testing

AbstractIn recent years there has been renewed interest on integral abutment bridges (IABs), mainly due to their low construction and maintenance cost. Owing to the monolithic connection between deck and abutments, there is strong soil‐structure interaction between the bridge and the backfill under both thermal action and earthquake shaking. Although some of the regions where IABs are adopted qualify as highly seismic, there is limited knowledge as to their dynamic behaviour and vulnerability under strong ground shaking. To develop a better understanding on the seismic behaviour of IABs, an extensive experimental campaign involving over 75 shaking table tests and 4800 time histories of recorded data, was carried out at EQUALS Laboratory, University of Bristol, under the auspices of EU‐sponsored SERA project (Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe). The tests were conducted on a 5 m long shear stack mounted on a 3 m × 3 m 6‐DOF earthquake simulator, focusing on interaction effects between a scaled bridge model, abutments, foundation piles and backfill soil. The study aims at (a) developing new scaling procedures for physical modelling of IABs, (b) investigating experimentally the potential benefits of adding compressible inclusions (CIs) between the abutment and the backfill and (c) exploring the influence of different types of connection between the abutment and the pile foundation. Results indicate that the CI reduces the accelerations on the bridge deck and the settlements in the backfill, while disconnecting piles from the cap decreases bending near the pile head.

Monitoring of the Response of the Sagamore Parkway Bridge and its Foundations During a Live Load Test

In this paper, we report the results of a live load test performed on the Sagamore Parkway bridge over the Wabash River, Indiana. The seven-span concrete bridge was constructed from 2016 to 2018 to replace the old, east-bound bridge. The main goals of the live load test were: (i) to study the transfer of the live loads from the bridge pier to the foundation elements and the distribution of live loads among the individual piles supporting the bridge pier; and (ii) to verify the assumptions (e.g., regarding the pile cap resistance) made in bridge foundation design. For these purposes, one of the interior piers (Pier 7) of the bridge and the fifteen pipe piles supporting it were instrumented with vibrating-wire strain gauges. With the bridge temporarily closed to traffic, the live load test was performed by parking twelve loaded triaxle trucks at specific locations on the bridge deck near Pier 7 in March 2019. The truck loads were applied in seven stages, simulating the driving of several trucks over the bridge pier. The settlement of the pier was measured using a digital level during the live load test. The data from the strain gauge readings were processed to produce the history of load distribution within the cross section of the pier and among the piles in the pile group during the seven stages of the live load test. The soil in contact with the pile cap carried about half of the total live load.

Probabilistic analysis of settlements under a pile foundation of a road bridge pylon

The paper addresses the reliability change of a road bridge pile foundation due to the unpredictable increase of settlements in time. The analysis is based on the Rędziński Bridge in Wrocław, Poland, its design assumptions, and monitoring results. The bridge foundation rests on a multi-layered subsoil assumed random. The Finite Element model of the subgrade is generated in ZSoil® software. To simplify the probabilistic approach, substitute soil strata stiffness parameters are adopted. Tracing their time decrement allows for a comprehensive definition of the entire foundation over-settlement produced by numerous factors. Preliminary sensitivity analysis of settlements to the stiffness variation properly simplifies the random model. The Serviceability Limit State helps to assess the foundation reliability index, further compared with the condition in the EN 1990:2002/A1:2005 standard. In addition, real-life settlements are also measured in the first year of bridge operation, they are used to calibrate the reliability index assessment. An innovative approach is proposed, where appropriate time-wise fluctuation functions represent the expected settlement increase and the related reliability reduction. These fluctuation functions help to plan the future remedial actions to maintain the initial bridge safety and to indicate the action frequency and scope. Future reliability levels may be extrapolated too. The real-life survey database of settlements makes it possible to validate the results of probabilistic calculations. A dedicated flowchart is devised to support further analysis of a wide structural domain.

STRENGTHENING OF THE FOUNDATIONS OF HIGHWAY BRIDGES IN THE CONTEXT OF THE PROBLEMATIC STATE OF THE TRANSPORTATION AND ROAD COMPLEX

Purpose. The aim of the work is to analyze the existing domestic and foreign methods of strengthening the foundations of road bridges, taking into account the influence of various factors and operating conditions of these objects in the context of the problematic state of the transport and road complex. Methodology. The problematic issues of ensuring the smooth functioning of transport routes in modern conditions are highlighted. Complex measures aimed at restoring the operation of the transport infrastructure by promptly responding to existing and emerging threats of disabling transport routes as a result of military operations, sabotage, natural disasters, and man-made accidents have been identified. Findings. Generalization of modern foreign and domestic methods of strengthening the foundations of bridges made it possible to study the most effective, cost-effective and simple in technological design structures. Four directions of development of strengthening of foundations are proposed: 1) increasing the support area of shallow foundations on natural bases; 2) installation of additional pile foundations with their integration into a common structural system with existing foundations and the construction of additional supports; 3) strengthening the existing pile foundations by changing the bearing capacity of the foundations; 4) constructing other structural elements to ensure the reinforcement of the existing foundations of bridges. Originality. It consists in setting the task of strengthening the foundations of road bridges in the context of the problematic state of the transport and road complex. Practical value. Based on the results of the analysis, it is possible to recommend the most economically justified and quickly implemented methods of strengthening the foundations of bridges for making design decisions in the implementation of state programs for the construction and development of the transport and road complex of Ukraine and in modern world practice.

Study of the Effect of Source Application on Sonic Echo Tests in Timber Piles

The long-term effects of scour have been identified as one of the primary reasons for bridge failure. To evaluate the performance of the bridges against scour, it is essential to assess the conditions of the bridge foundation including the depth of the piles. Sonic Echo (SE) has been a favorable nondestructive method to evaluate the condition of unknown bridge foundations in the recent decades. Previous studies have shown that the results obtained from SE tests can be affected by a variety of factors such as the pile-to-soil stiffness ratio, length-to-diameter ratio of the pile, presence of defects and anomalies near the pile head, striking method, and hammer type. Although previous studies have discussed such affecting factors, there is a lack of comprehensive investigation regarding the effect of striking method and hammer tip type specific to wood piles supporting bridge decks. In the current study, the effect of striking method and hammer type on the success of SE tests conducted on wood piles has been scrutinized by investigating various options of striking methods and hammer tip types. After comparing different options, superior ones were identified and recommendations for better conducting the SE tests on unknown wood bridge foundations were presented. Numerical simulations were also performed to support some of the conclusions.

Calculation of influence range of impact holing on the adjacent railway

In order to solve the impact of actual construction projects on the existing surrounding environment, the impact and vibration of the impact on the existing railway subgrade stability caused by the construction of the bridge foundation are analyzed. Based on the actual case of the construction project of No. 37 main pier across the Jiaoji Railway Main Bridge at Binlai expressway, the influence of the impact holing on the adjacent railway is analyzed. The influence range of the construction vibration is based on the Chinese Seismic Intensity Scale (GB/T 17742-2008) and Safety Regulations for Blasting (GB6722-2014), and taking the maximum velocity allowable value as criterion, the minimum safety range of impact drilling is obtained. Using the theory of small hole expansion to calculate the influence of the effect of soil compaction, the minimum allowable value of safe distance for the Construction technology of impact forming hole is considered 6.5m; in addition, based on the numerical simulation of nonlinear time history analysis, a reasonable exciting force parameter is given for practical engineering. The influence of impact amplitude A and impact frequency f on construction safety distance is analyzed. The results show that: The minimum safety distance of impact drilling is linear with the increase of impact amplitude A. When the impact frequency f is greater than 10Hz, the minimum safety distance tends to a fixed value as f increases. The results of this study guide the actual construction of the field, it guarantees the normal traffic of the Jiaoji Railway and provides a theoretical support for similar projects.