Bridge Pile Research Articles

Study on Influence of Shallow Buried Tunnel Excavation on Adjacent Bridge Piles

Study on Influence of Shallow Buried Tunnel Excavation on Adjacent Bridge Piles

Numerical Simulation of Flood Control Levee Deformation by Shield Tunnel Excavation through the Liuyang River: A Case Study

The interval section of the Liuyang River flood control levee project of the Changsha Metro Line 6 is used as the engineering background of this study. A three-dimensional finite element numerical model of a tunnel shield containing complex interfaces is established by using the multifield coupling software COMSOL. The paper studied the deformation of flood control levees under shield tunnel excavation working conditions. The results show that when the left line shield machine is excavated below the Liuyang River flood control levee, the deformation of the flood control levee and the surrounding rock of the tunnel is biased towards the built right line tunnel. And it has an impact on the bridge pile near the tunnel. When the shield of the left line crosses the flood control levee, it can easily cause a large deformation and displacement of the levee above the area between the two shields. To ensure the controlled deformation of the levee, the construction should ensure the spacing between the two tunnel palm faces as far as possible and should be far away from other structures on the levee. When the shield crosses the levee, the deformation that occurs at the base of the levee is significantly higher than the deformations that occur at other locations of the levee. Displacement monitoring and secondary reinforcement at the base of the flood control levee appear to be necessary. The numerical simulation results validate the feasibility of using the multifield coupling software COMSOL to study the construction modeling of shield tunnels through rivers and its advantages. This method provides a practical framework for similar tunnel performance engineering or displacement monitoring in future projects.

Numerical simulation of scouring around groups of six cylinders with different flow directions

ABSTRACT Scouring around the pile foundation is one of the potential failures of offshore bridges that must be assessed due to the possibility of damaging the bridge structure. However, there is still few in-depth research regarding local scour simulations around groups of six cylinders consisting of more than one row, which is most widely used for group arrangement performed numerically. The maximum scour depth and its mechanism surrounding the six-cylinder group were determined by numerical simulation of scour consisting of multiple rows arranged side-by-side and in tandem with different pile spacing ratios using Flow-3D software. A validation study using experimental investigation was completed to verify the accuracy of the computational model. Numerical simulations employing the Van Rijn transport rate Equation and the RNG k – ɛ turbulence model produced results for scour depth evolution and bed elevation contour, which were in accordance with the experimental study. The numerical results show that the best arrangement for the minimum scour depth of the six-cylinder group is the tandem arrangement of two rows and three columns with pile spacing ratio of 3.5. As a result of this study, engineers can optimize the design of bridge pile foundations to enhance safety and economic efficiency.

Study on the vertical bearing performances of piles on karst cave

Caves affected the load transfer mechanism of bridge pile foundation, and then the safety of the bridge was threatened. This study was to investigate the effect of karst cave under bridge pile foundations on the vertical bearing characteristics of bridge pile foundations by static load test, finite element analysis and mechanical model. The settlement of the pile was measured by displacement meter, and the axial force were measured by stress gauges in the test. The load-settlement, the axial force, the unit skin friction and the ratios of side and tip resistances were compared with the result of the simulation. Then sixteen conditions were selected in finite element analysis, one of them was a conventional pile not on cave. The others were about five kinds of height, five kinds of span and six kinds roof’s thickness of the cave. The simply supported and fixed wide beam were established to calculate the allowance roof thickness. The results reveal that when the cave span is greater than 9 m × 9 m or the roof thickness is less than 2 D (pile diameter), the stress and deformation of piles are significantly affected.

Analysis on Bearing Behavior of Single Pile under Combined Action of Vertical Load and Torque in Expansive Soil

To reasonably analyze the bearing characteristics of curved beam bridge pile foundation under the combined action of vertical force (V) and torque (T) in expansive soil, a method of determining Tu (limit torque) under the action of V is proposed. Considering the effects of expansive force and ground heave after immersion, the load transfer function at the pile–soil interface with positive and negative friction resistance is established. The nonlinear solution of a single pile under vertical load is achieved by the finite difference method. Subsequently, the circumferential limit friction resistance is modified, and a loop iteration program is compiled through MATLAB. Thus, the bearing capacity of single pile under the loading path of V→T is obtained. The corresponding failure envelope curve is drawn and verified by laboratory model tests. Based on the verified solution, the bearing capacity envelope curve and deformation characteristics of single pile are analyzed. The influence of the expansion rate on the bearing capacity envelope curve is discussed, and reasonable engineering suggestions are put forward.

Shaking table test research on short-distance side-piercing bridge piles in tunnel structures

More and more projects of underground tunnels side-piercing bridge piles have emerged in recent years. In this paper, in order to investigate the law of seismic response of a short-distance side-piercing bridge pile system in a tunnel structure, a shaking table was designed and implemented, which is based on the actual engineering background of a tunnel crossing the elevated Line 3 bridge pile in Dalian, China. Based on relevant test data, the acceleration and strain responses of the site and structure were analyzed and quantitatively evaluated. The analysis results showed that the presence of a tunnel or bridge pile structure significantly reduces the frequency of the system. Regarding the law of seismic response of interaction system, it was found that the existence of the tunnel structure and bridge pile has weakened the rigidity of the whole model, and therefore, the seismic response of surrounding soil was amplified. It was observed that the bridge pile suppresses the seismic response of the tunnel; however, the tunnel will amplify the acceleration response of the bridge pile. In addition, the existence of bridge piles increases the strain response of the tunnel, and the strain at the bottom of the bridge piles increases due to the influence of the sidewall of the tunnel.

Effect of a Circular Cylinder on Hydrodynamic Characteristics over a Strongly Curved Channel

Curved channels are one of the most fundamental units of natural or artificial channels, in which there are different kinds of obstacles; these include vegetation patches, bridge piles, electrical tower foundations, etc., which are all present over a channel bend, and can significantly alter the hydrodynamic characteristics of a channel when compared to a bare bed. In this study, laboratory experiments and numerical simulations were combined to investigate the effect of a circular cylinder on the flow characteristics of a 180-degree U-shaped curved channel. Experimental data, including on water depth and three-dimensional velocity, which was obtained by utilizing acoustic Doppler velocimetry (ADV), were used to calibrate and verify the simulation results of the Reynolds-Averaged Navier–Stokes (RANS) model in the FLOW-3D software. Numerical results show that a larger cylinder diameter leads to an overall greater depth-averaged velocity at the section, a greater shear stress acting on the banks on which the cylinder is placed, and a greater increase in the depth-averaged velocity along the concave bank compared to that along the convex bank. When the diameter of the cylinder placed at the 90° section increases, two weaker circulations with the same direction are found near the water surface; for the submerged one, the two weaker circulations appear at the further downstream section, unlike the emergent one. The degree of variation degree in the shear stress acting on the banks is larger than that of the flowrate. As the flowrate increases or the radius of curvature decreases, the secondary flow intensity correspondingly elevates. However, the curvature radius of the curved channel plays a more important role in the secondary flow intensity than the flowrate does. For both the emergent and submergent cylinders, the large cylinder produces a greater secondary flow strength, but the emergent one has a greater secondary flow strength than the submergent one. In summary, the present study provides valuable knowledge on the hydrodynamics of flow around emergent and submergent structures over a curved channel, which could improve the future design of these structures.

Study on Horizontal Bearing Capacity of Pile Group Foundation Composed of Inclined and Straight Piles

In all types of new arch bridge structures, the requirements of the foundation are becoming more and more strict. Under the action of horizontal thrust, the distribution of the internal forces of the pile group in which inclined piles participate in an arch foundation is complicated. In this regard, the horizontal forces of each pile in a pile group and the horizontal bearing performance of each pile in a pile group under the action of total thrust are investigated by establishing a pile group foundation model and a p-y curve difference equation. After an in-depth analysis of the simulation results, it is found that the load distribution calculated by the finite element method is very close to that calculated by the p-y curve method, both in terms of curve shape and numerical value, indicating that the pile top load distribution is close to the actual situation. In addition, the maximum shear force of each pile body occurs at the top of the pile, and the maximum bending moment occurs at the point 1/5 away from the top of the pile. Finally, the nonlinear analysis of the p-y curve method can be well applied to the calculation of bridge pile foundations.

Physics-Informed Optimization for Dynamic Soil–Structure Interaction Analysis of a Pile Partially Embedded in Nonlayered Soils

This study proposes a novel physics-informed optimization approach to account for nonlayered soil conditions for the dynamic soil–structure interaction analysis that is critical for structural health monitoring involving soil–structure interaction. This approach can estimate soil properties based on a few measurements and then predict the natural frequency of structures, a key element that has been very often utilized for structural health monitoring and evaluation. A case study for frequency-based bridge scour detection has been presented for the demonstration of this approach, where a bridge pile is partially embedded in complex nonlayered soils. With this case study, we show that the nonlinear frequency–scour depth relationship can be accurately estimated using 2–4 measured data points, which is in favor of situations where conducting a field test is difficult or the demand for conducting field measurements needs to be reduced. The impact of errors resulting from measurement uncertainty on the performance of this approach is found to be insignificant. This physics-informed optimization approach thus can help analyze dynamic responses of engineering structures in complex nonlayered soil conditions involving soil–structure interaction.

Bridge-piling modifications on the momentum balance in an estuary: The role of tides, winds and seasonality

Marine structures modify the hydrodynamics in relatively shallow coastal areas such as bays and estuaries, as analyzed here in the Bay of Cádiz. This study explores the momentum balance and the wakes generated by bridge piles, through a validated numerical model of a well-mixed mesotidal estuary. Three main drivers are considered: tides, winds and buoyancy forcing. The results show that the contribution of advection has the same order of magnitude as that of the barotropicity, with baroclinicity being relevant only during summer. The effects of the pile are intensified inside the basin (i.e., the bay) during spring-tides and ebb periods, and outside the bay during neap-tides and flood periods. These changes in the momentum balance reach up to 1 km landward in the deepest areas and up to 2 km seaward in the shallowest areas. The momentum terms vary the most in spring and summer, when wind forcing is weak. Westerly winds coinciding with flood-tide periods increase the advection in the outer basin, because of the pile. In contrast, easterly winds coinciding with the ebbing tides intensify the advection in the inner basin. Results can be extrapolated to other study sites with similar human interventions such as wind or wave energy converters.

Investigation on the Influence of Active Underpinning Process on Bridge Substructures during Shield Tunnelling: Numerical Simulation and Field Monitoring

The pile foundation cutting and underpinning process during shield tunnelling significantly impacts the stability of bridge substructures. In this paper, the shield tunnel area from Hongguzhong Avenue Station to Yangming Park Station of Nanchang Metro Line 2 was taken as the research subject, which crosses the pile foundation underpinning project of the south approach section of Bayi Bridge. Through numerical simulation and on-site monitoring analysis, the influence of the active underpinning process of shield tunnelling pile foundation on the deformation of bridge substructure was studied. First, through analyzing on-site conditions and comparing technical solutions, an active gantry bridge pile foundation underpinning technology was proposed, and the specific construction steps were determined. On this basis, for the C15 pile foundation with the most complex working conditions, ABAQUS software was applied to simulate the jack-up, unloading and pile-cutting process during the pile foundation underpinning construction, and the displacement development of the bridge pier, underpinning beam and new pile during the whole construction process were analyzed. Finally, through on-site monitoring data analysis, the technology’s feasibility and safety were further verified. At the same time, according to the analysis of the monitoring results of the bridge piers, underpinning beams and new piles, the results from the finite element software were nearly the same as the trend shown by the monitoring results, and the displacement of the main structures of the lower part of the bridge was small and within the control range. The above research work verified the applicability of the active gantry type bridge pile foundation underpinning technology in the pile foundation underpinning condition of the single-column single-pile bridge in the narrow space curved bridge section, and is worthy of further promotion and application.

Dynamic Response Analysis of Coastal Piled Bridge Pier Subjected to Current, Wave and Earthquake Actions with Different Structure Orientations

The goal of the experiment described in this paper was to examine the effects of structure orientation (0°–90°) and fluid–structure interaction (FSI) under combined water loads, represented by water current and waves, and earthquake actions, on the dynamic response of a reduced-scale bridge pier specimen with pile foundation. The peak relative displacement and peak acceleration of the specimen are measured using the first time innovative in Iraq, Reality Water–Structure–Earthquake Interaction Test (RWSEIT). The findings are given and analyzed concerning water depths, current speed, wave characteristics, earthquake amplitudes, and structural orientations. A numerical model of the examined specimen with three dimensions (3D) was constructed, and the findings were successfully confirmed using the data from the experiments. A pile foundation bridge pier's 3D structural response under orientations that cannot be tested in a lab was computed using the constructed numerical model. The complicated dynamically produced FSI effects on the response of coastal pile foundation bridges may be better understood according to the research's experimental and numerical findings.

Experimental Analysis of Vertical Deformation and Bearing Characteristics of Bridge Piles in High and Steep Slopes

More and more rigid frame bridges with high piers and large spans are built in the high and steep slope areas of deep valleys in southwest China. The slow deformation of the slope in the geological sense often causes the problems of piles, which in turn causes damage of the upper bridges. The vertical bearing characteristics of bridge piles in slope still need to be conducted because of the peculiarity of slope topography. The vertical deformation and bearing characteristics of piles in the slope area were experimentally studied by considering different influencing factors and the fitting formula for the ultimate bearing capacity of the piles under vertical load is obtained. The results show that the vertical deformation and ultimate bearing capacity (defined by vertical limit settlement deformation of 0.013 times the pile diameter) of the pile are closely related to its position in the slope. The pile in the middle of the slope has the lowest vertical ultimate bearing capacity. Moreover, the side frictional resistance transfer depth of the pile in continuous slope is greater than that of the pile in unilateral slope. Additionally, the slope angle has a significant influence on the vertical bearing performance of piles. The delayed settlement of the pile top decreases approximately 40% at most and the vertical ultimate bearing capacity of the pile increases 48.6% at most as the slope angle decreases by 15°. Meanwhile, the side friction resistance of the pile increases with the decrease of slope angle. The bending moment applied to the pile top reduces the vertical ultimate bearing capacity of the pile and increases the axial force of the pile body. The results can provide data support for pile design and instability judgment with similar geological conditions.

Soil Interaction of H-shaped Steel-RC Stepped Pile of Integral Abutment Bridge: Experimental Evaluation

The reinforced concrete piles (RC) in integral abutment bridges (IABs) are challenging to meet the longitudinal deformation of bridges with significant lateral stiffness. The H-shaped steel (HS) piles are costly and prone to corrosion. This paper proposes a new form of pile comprised of HS and RC piles in series to meet the longitudinal deformation demand of IABs. Tests were conducted for one HS pile under reciprocating low-cycle pseudo-static test and two HS-RC stepped piles with different bending stiffness ratios of HS/RC (0.25 and 0.5) using the HS-RC pile test model,. The influence of the stiffness ratio on the mechanical behavior of stepped pile-soil was studied. The mechanical behavior of the stepped pile was also compared with single HS and RC piles. and the applicability of the m and p-y curve methods to the calculation of horizontal displacement of stepped pile is discussed. The results show that the elastic deformation range of the HS pile is 2 mm to 25 mm, and its horizontal deformation capacity and bearing capacity are excellent. As the stiffness ratio increases, the stepped pile-soil system's yield displacement and yield load increased. The stiffness ratio has no significant effect on the failure mode of the piles. The hysteretic ring of the stepped pile shows a squeezing shape at the initial loading stage, but becomes a full spindle in the later loading stage. The stepped pile shows an excellent energy consumption effect and a horizontal deformation ability, indicating it is suitable for IABs. The m method has better accuracy only up to 2 mm displacement, while the p-y curve method still has higher accuracy within 15 mm.

Seismic Response Analysis of Rock-Socketed Piles in Karst Areas under Vertical Loads

Karst landforms constitute one of the most harmful geological conditions, which have an adverse effect on the deep foundation structures of bridges. During earthquakes, the existence of karst caves can cause serious seismic damage to the bridge pile foundation. In order to investigate the seismic response of rock-socketed piles under vertical loads in complex karst cave conditions, finite element numerical simulation analyses were carried out, referring to the practical major bridge structure rock-socketed pile project in China. The peak strain distributions of rock-socketed pile foundation influenced by single-karst cave factors under the combined action of vertical loads and ground motions were investigated, and the influences of complex multi-caves were further explored. The results showed that the restraint effect of the bedrock near the pile would gradually decrease with the increase of the height of the karst cave and the decrease of the height of the karst cave roof; under the condition of a beaded karst cave, the constraint of bedrock between the karst caves makes the pile present the distribution characteristics of “multi-segment and multi-broken line”; under the condition of an underlying karst cave, the existence of the underlying karst cave would decrease the restraint of the bedrock at the bottom pile and increase the peak strain of the pile to a certain extent. This paper revealed the seismic response law of the rock-socketed pile under vertical loads within various complex karst cave conditions and developed reasonable reinforcement measures aiming at dangerous locations, providing important engineering guidance and a reference for the seismic design of rock-socketed pile foundation in complex karst areas.

Perancangan Vertical Axis Twin Turbine Pada Pembangkit Listrik Arus Laut Di Suramadu

Renewable energy sources are environmentally friendly energy sources that do not pollute the environment and do not contribute to climate change and global warming as in other traditional sources. Ocean currents are the movement of seawater masses from one place to another either vertically (upward motion) or horizontally (sideways movement) towards equilibrium, or the very wide movement of water that occurs throughout the world's oceans. In this study using experimental research where the maximum ocean current speed results in pile 56 were only 1.28 m / s, the turbine will need a greater speed to beat the initial torque of the 5 kW generator. The results of the 12-day test showed that the speed of the ocean current at Suramadu Bridge pile 56 ranged from 0 - 70 cm/s and only 1 week with a maximum ocean current speed, which was 128 cm/s. When using a 5 kW generator, it is likely that the generator will rotate and generate electric current for only a week. Beyond that the generator does not rotate because the speed of the ocean current is low. Therefore, the condition that the initial torque is obviously smaller than 10 kW in the twin turbines installed 3 generators each are 3.5 kW so that the turbine is still able to rotate at low current speeds such as the speed of ocean currents in Suramadu and generally Indonesian waters.

Study on the Application of Elastic Wave CT Technique to Detect the Effect of Post-Grouting of Pile Foundation

The post-grouting technology can effectively improve the bearing capacity and reliability of foundation piles, and it is of great academic and economic significance to evaluate the effect of post-grouting. However, in general, the evaluation of the effect of post-grouting slurry on foundation piles is still relatively single, and most researchers only test the improvement of the bearing characteristics of post-grouting piles, but there are few research results on the distribution state of slurry consolidation and the range of the reinforced soil. In this paper, elastic wave CT was used to detect the bridge piles of Taizhou Bay Du Xiaipu Bridge, and elastic wave CT technology was applied to the detection of the post-grouting effect of foundation piles experimentally. The spatial distribution characteristics of the underground grouting reinforcement area were revealed from the perspective of visualization, and the influencing factors of the elastic wave inversion results were analyzed. The conclusions obtained from elastic wave CT detection were similar to those of electromagnetic wave CT, and the laws are basically consistent with the current engineering experience, reflecting the applicability of using elastic wave CT to detect the effect of post-grouting of pile foundation.

Research on the Interaction between the Pile and Shield Machine in the Process of Cutting a Reinforced Concrete Pile Foundation

As the urban underground space environment gets more complex, the cases of shield machines encountering and cutting through piles are becoming more common. The interaction between the cutter head and pile foundation directly affects the tunneling performance of the shield machine and the safety of the existing structure. To study the interaction between the pile and the shield machine, a calculation model of the interaction force is established. A field test of cutting two piles was conducted and the rationality of the model is verified by comparing the calculation results with field test data. The model is applied in the project of a shield machine cutting bridge piles in Harbin Metro Line 3, China. The shield operation parameters are predicted and compared with field test results. Besides, the impacts of cutting surface width and eccentric distance on interaction force are discussed. The study shows that there is a significant interaction between the cutter head and the piles when the shield machine cuts reinforced concrete piles, which causes obvious changes in the shield operation parameters and shield performance. The number of tools that are inside the cutting area has a significant effect on the additional torque. The additional torque fluctuates with the rotation of cutter head and increases with the increase of the number of tools. The number of these tools is determined by factors such as the layout of tools in the cutter head, cutting surface width and eccentric distance, which influence the position of each tool relative to the cutting area. As the cutting distance increase, the additional torque of the cutter head shows a trend of first increasing and then decreasing and reaches the maximum value when the cutting distance reaches the radius of the pile. Besides, the additional force and additional moment of the cutter head increase with the increase of the cutting surface width. The impacts of eccentric distance on additional force and additional moment are complicated. The results in this paper can provide reference for similar engineering.

Shaking Table Test and Numerical Simulation Study on Tunnel-Soil-Bridge Pile Structure Interaction System

In this study, based on the actual project in Dalian, the dynamic interaction of the double tunnel sand bridge pile system (SSSI) under earthquake action is studied by shaking table test, and the dynamic response laws of the structure and site are obtained, which are compared with ABAQUS numerical simulation. The Kelvin constitutive model subprogram is introduced into the numerical model, and the equivalent linear method is used to deal with the nonlinear problems of sand in the calculation process. The experimental results are compared with the results obtained using the numerical model to verify the reliability of the numerical simulation. Based on this, eight working conditions are designed, and the interaction law between the structures in the system is investigated through a comparative analysis. The results showed that the tunnel amplifies the dynamic responses of the bridge pile, adjacent tunnel, and far field, while the bridge pile attenuates the dynamic responses of the side tunnel and far field; the presence of both the tunnel and bridge pile increases the internal force of the adjacent structure, and the peak internal force often occurs near the intersection of the structure or at the pile–soil interface.

Soil Heterogeneity Effects on Bridge Piles Deformation under Shield Tunnelling Disturbance

This research examines the impact of soil heterogeneity on the bridge piles beneath a nearby tunnel excavation using Monte-Carlo stochastic analysis. Sensitivity analysis is specifically used to the variation of stratum range, variation coefficient (COV), and fluctuation distance of the soil Young’s modulus. Meanwhile, the reliability evaluation approach is also applied to systematically examine the impact of COV on the likelihood of a pile failing. The findings suggest that more consideration should be given to the degree and range of geological parameter variations in the strata surrounding the tunnel. The horizontal and vertical fluctuation distances in this project are predicted to be around 18 m and 4.5 m, respectively. The fluctuation range influences the frequency of low stiffness zones in the soil. Additionally, the variation coefficient has a significant effect on the pile deformation, presenting a positive association. The pile deformation exhibits an increasing tendency in the wake of the growing variation coefficient. More significantly, the increase of the COV will directly lead to a rising failure probability of the pile settlement. According to extensive Monte-Carlo simulation calculations, the simulation results considering the variability of soil parameters have a certain deviation from the deterministic in the perspective of probability statistics. It is quite necessary to attach importance to the soil heterogeneity effects in the pile foundation stability under construction disturbance.