Bridge Pile Research Articles

Influence of seasonal freezing-thawing soils on seismic performance of high-rise cap pile foundation in permafrost regions

The active layer in permafrost region is inevitably subjected to seasonal freezing-thawing actions. The soil freezing and thawing can change boundary conditions of the bridge pile foundation in permafrost region, which will influence the seismic responses of the bridge. In this study, to investigate the influence of seasonal freezing-thawing soils on seismic performance of high-rise cap pile foundation in permafrost region, quasi-static tests were carried out on two 1/8 scaled models. The hysteretic behaviors and damage characteristics of the pier-pile-soil system in permafrost region with thawed and frozen active layer were analyzed. It is found that the freezing-thawing status of the active layer can relocate the vulnerable position of the pile foundation in permafrost region. Furthermore, the frozen active layer limited the deformation capacity of the pier-pile-soil system, then resulted in the redistribution of the pile stress. Although the frozen active layer in winter season enhanced the bearing capacity of the pier-pile-soil system, it weakened the ductility of the pier-pile-soil system. Additionally, the frozen soil temperature and the shear strength of the active layers will affect the adhesive force of the permafrost layer. These results can provide a scientific basis for the seismic design of bridges with pile foundation in permafrost regions.

Bridge-piling modifications on tidal flows in an estuary

This paper investigates the impact of the bridge-pilling modifications on the tidal flow at the strait of a human-altered mesotidal estuary (Cádiz Bay, Spain). The analysis was accomplished by combining (1) field data of current velocities in a cross-section close to the pile of a recently built bridge, and (2) hydrodynamics results from the calibrated and tested DELFT3D numerical model on the study site. The analysis was focused on bridge piling effects at intratidal scale during neap and spring tides. Semidiurnal (D2), quarti-diurnal (D4) and sixth-diurnal (D6) bands were examined. The ratio of quarter-diurnal to semidiurnal amplitudes (D4/D2) is largest (¿1) near the bottom of the channel due to friction, and the ratio D6/D2 is largest (¿1.5) close to the pile and in the shallowest part of the cross-section, due to internal asymmetry and tidal advective accelerations. Comparing neap and spring tides, the most marked asymmetries are found in the latter. These asymmetries occur around the wake of the pile, alternating from flood to ebb. The location of the bridge pile causes a decrease in the amplitude of D2 (50%), and a phase lag in the tidal wave of 30 min. The D6 amplitude increases up to almost 100% due to distortion of the tidal wave induce by the wake created at the pile. Moreover, the pile reduces about 1 m the depth where the pycnocline is observed. Additionally, the pile can be considered as an obstacle for the sediment flux. These effects can be extrapolated to similar infrastructures, such as wind or wave energy farms, that can potentially modify the estuarine dynamics. • Tidal flow is modified by a bridge piling in an estuary. • The M2 tidal amplitude is reduced up to 50% near the pile. • The pile causes a 30-min phase lag in the pile wake. • The sixth-diurnal tidal band increases up to 100%. • The center of the pycnocline is deepened by 1 m.

ANALISIS STRUKTUR SLAB ON PILE STUDI KASUS JALAN TOL SEMARANG – DEMAK SEKSI 2

<strong><em>Slab on pile is one of the bridge structures used in the Semarang Demak Toll Road Project Section 2. The slab on pile structure consists of a slab, pile head, and piles. There are 2 (two) typical slab on pile bridges at this location, which are distinguished by the number and distance of the piles. 5 (five) piles in 1 (one) pile head with a spacing of 3.5 meters are used for piles with a freestanding of less than 6 meters. This pile configuration is located at STA 19 +658 to 19+793. Meanwhile, 6 (six) piles with a space of 2.8 m are used for piles with freestanding of more than 6 meters. This pile configuration is located at STA 19+800 to 19+894. At STA 19+674 there is an expansion joint that functions to accommodate all forms of movement that occur in the slab on pile structure. In addition, the span between the piles in the longitudinal direction is 7 meters. This slab on pile planning (SNI 1725:2016) "Loading for Bridges" and "Bridge Planning for Earthquake Loads" (SNI 2833:2016). Slab on pile planning is carried out with the help of SAP2000 software to determine the internal forces that occur in the slab on pile structure. The foundation system used in the modeling is a pile with spring support where the function of the spring support is to represent the nature of the soil. The result of this plan is to obtain a slab on pile structure design along with shop drawings.</em></strong>

RELIABILITY-BASED INVESTIGATION ON THE COMPRESSIVE STRENGTH OF COMMONLY USED NIGERIAN TIMBER SPECIES

This paper considers the compressive strength both parallel and perpendicular to grain of not less than twenty Nigerian-grown timber species out of which, six commonly used ones were selected and their compressive resistance assessed under certain loads. First, it was found out that the basic compressive stress perpendicular to the grain of timber is about 22% of the basic compressive stress parallel to grain. A reliability assessment was then carried out using the First Order Reliability Method (FORM) to investigate the performance of a column section of 250 x 250mm and 300 x 300mm for the six Nigerian-grown timber species. Lophira alata was found to be the most reliable with a Probability of failure Pf = 2.78 x 10-3 and 7.1 x 10-2 under an axial load of 1000kN and 2000kN respectively. This was followed by Anogeissus leiocarpus with Pf = 2.53 x 10-2 and 5.26 x 10-3 under an axial load of 1000kN and 1500kN respectively. Others that followed were ‘Iroko’(Chlorophora excelsa),‘Abura’ (Mitragyna ciliata),‘Afara’ (Terminalia superba), and ‘Obeche’(Triplochiton scleroxylon), in the order of descending performance. It can been established from this study that, ‘Ekki’ (Lophira alata) and African birch (Anogeissus leiocarpus) could be suitable for bridge piles and piers, railways or related structures that require compressive members with high axial capacity whereas, ‘Abura’, ‘Obeche’, ‘Afara’ and ‘Abura’ would be best suitable for buildings.

Effect of Permafrost on Seismic Performance of Railway Bridge Pile Foundation with Elevated Cap

Pile foundation with elevated cap is always applied for railway bridges in permafrost region to minimize the thermal disturbance to vulnerable permafrost. Permafrost can influence the failure characteristics of the pile foundation under earthquakes and complicate the seismic performance evaluation of railway bridges with pile foundations in seismically active zones. Quasi-static tests of reduced scale models were carried out to investigate failure characteristics and hysteretic behaviors of the pile foundation with elevated cap in permafrost. Test results showed that the existence of permafrost can increase the stiffness of the foundation soil and then inhibit crack propagation of the unfrozen topsoil around the bridge pile foundation. Quite differently from the pile foundation in unfrozen soils, severer damages occurred at the pile foundation in soils with permafrost. Thus, the topsoil crack will be mitigated while the pile failure will be aggravated if strong earthquake occurs in permafrost regions for railway bridge pile foundation with elevated cap. Otherwise, the permafrost significantly influenced the loading bearing capacity and deformation features of the pile-soil interaction (PSI) system under seismic loads. The PSI system with permafrost has better energy dissipation than that with unfrozen soils due to the severe damage of the pile foundation. A simplified formula was developed to estimate the equivalent stiffness of the PSI system. It is indicated that the stiffness of the PSI system with permafrost degraded more severely than that with unfrozen soils. Therefore, permafrost effect cannot be neglected in seismic design of railway bridge pile foundations with elevated cap.

Numerical Simulation of Mechanical Response of Bridge Foundation and Existing Tunnel Caused by Pipe Jacking Construction

Upward ( phase i ) pipe jacking project of hangzhou water intake is near existing bridge foundation and operating tunnel. In order to investigate the influence of pipe jacking construction process on existing structures, Plaxis 2D finite element software was used to simulate the horizontal and vertical displacement of existing structures caused by pipe jacking construction. The calculation results show that: The horizontal displacement of bridge pile foundation is nonlinear distribution. There is a bending point in the pile foundation. The maximum and minimum horizontal displacement are 0.71 mm and-0.84 mm, respectively. The maximum vertical settlement is only 0.29 mm. The horizontal displacement of the sidewall of the tunnel structure is nonlinear distributed, and the displacement near the pipe jacking is relatively large, but the maximum displacement is only 0.13 mm. The vertical deformation of tunnel structure is mainly uplift deformation, and the uplift near the pipe jacking is obvious, but the extreme value of uplift is only 0.09 mm. Thus, the impact of pipe jacking construction on bridges and tunnels is very limited. The research results are of great significance to the safety evaluation of pipe jacking engineering near construction.

Numerical Investigation into Lateral Behavior of Monopile Due to Scour Enhanced: Role of State-Dependent Dilatancy

The removal of soil during scouring is crucial to the lateral resistance of piles in bridges of railways or highways. In this process, dilatancy of the interface soil induces variation in normal stress, which in turn influences the interface soil lateral resistance. Due to the lack of analysis in previous studies in terms of cohesionless soil state (i.e., relative density and stress level) in remaining soil after scouring, it is difficult to simulate the properties and behavior of interface soil. The objective of this study is to explain the change of the sand state at the compression interface after scouring, quantify the stress-strain characteristics of the pile during this period and eventually present the prediction p-y curves of the lateral service capacity. The state-dependent constitutive model for saturated sand is employed, combined with the 3D finite element simulation, and the state development of the remaining soil is exhibited. The enhancement of dilation and stress relief of the remaining shallow horizon eventually gives rise to the reduction of the lateral resistance. In addition, the remaining overburden soil surrounding the pile restricts the interface soil, enlarging the normal stress and strengthening the deep horizon. Then, the friction angle considered the influence of state-dependent changes is used to quantify the hyperbolic p-y curves.

Dynamic Response of Bridge-Landslide Parallel System under Earthquake

In order to further understand the instability mechanism and geohazard causation when the main sliding path of the slope body is parallel to the path of the bridge, the corresponding bridge-landslide parallel system is constructed for shaking table tests. This paper summarizes the combination forms of bridge-landslide model under different position and focused on the slope body located above the bridge deck. Firstly, based on the shaking table test results of El Centro (1940), the failure behavior of bridge-landslide parallel system was evaluated, and the changes of acceleration and deformation of bridge pile were subsequently analyzed. Then, the interaction bridge structure and sliding body were explained by the spectral features. The main conclusions are as follows. First, in the model test, the landslide belongs to the thrust-type landslide. Due to the barrier function of the bridge, the main failure site of landslide occurs in the middle and trailing edge of slope body. At the same time, the acceleration value of earthquake waves is 0.3 g, which is the key to this variation. Second, the acceleration response of the measuring points on the bridge pile and landslide increases with the increase of ground elevation. If the slope structure is damaged severely, the deformation response of weak interlayer is inconsistent with the surrounding soil structure. Third, with the increase of excitation power, the dominant frequency of bridge-landslide parallel system gradually transitions from low to high frequency rate, and the interaction of the parallel system weakens the influence of river direction on frequency. Finally, under the same working condition, the dynamic response of the measuring points has obvious regularity with the change of situation. But the response of the same points is not regular due to the different earthquake excitation intensity.

Integrity Testing of a Platform‐Pile System Using a Sensor Array and Wavenumber Domain Analysis

Appropriate impact and sensor locations must be chosen in pile integrity tests to prevent three‐dimensional effects caused by the torsional and flexural modes. The three‐dimensional characteristics cause high‐frequency interference, especially in bridge and wharf piles. A method is required to minimize the high‐frequency interference without reducing the accuracy of the pile integrity test. A multivelocity integrity test method is proposed based on a sensor array and frequency‐wavenumber (FK) domain analysis to eliminate high‐frequency interference and reduce the errors in the output of integrity tests of platform‐pile systems. FK filtering is performed to eliminate the spatial alias frequency and separate the upward and downward wavefield and the vibration modes in an integrity test of a platform‐pile system. The optimum sensor location to minimize the influence of interference signals is at the bending plane relative to the impact location. Using a sensor array reduces the influence of the sensor location on the test results and minimizes the requirements for determining the location of the excitation point and sensors in the traditional low‐strain integrity testing (LST) method, thereby improving the applicability of this method.

Talking about the influence of foundation pit excavation on surrounding buildings

Foundation pit engineering is one of the important systems studied in geotechnical engineering. The study of foundation pit not only studies its own stability during excavation, but also analyzes its influence on surrounding building structures. This paper analyzes and summarizes the influence rules of foundation pit excavation on adjacent bridge piles, subway tunnels and houses from the aspects of influence principle, theoretical analysis method, selection of supporting structure and influence factors.

Numerical Simulation of Local Scour around Three Cylindrical Piles in a Tandem Arrangement

Scouring is one of the most common potential causes of bridge pile foundation failure with loss of life, economic and environmental impacts. Comprehensive studies on the numerical simulation of local scour around pile groups are still limited. This paper presents a numerical simulation using Flow-3D software to calculate the maximum sediment scour depth and investigate the mechanism around the groups of three cylinders in a tandem arrangement. A validation using the experimental study was carried out to confirm the reliability of the present numerical model. By using the Van Rijn transport rate equation and RNG k-ε turbulence model, the results of time evolution of scour depth and bed elevation contour show good agreement with the experimental study. The numerical simulation of three cylinders in a tandem arrangement were conducted with pile spacing ratios, G/D of 2 and 3. The local scour is affected by the horseshoe vortex from the downflow driven by the downward pressure gradient and rotates in front of the pile and the high bed shear stress, triggered by flow acceleration. The deepest maximum local scour depth is always obtained by the front pile as a shield pile, followed by the piles behind. The trend of the maximum local scour depth in a tandem arrangement is in accordance with the experimental studies and has a better agreement than previous numerical studies with the same model setup. This means that the numerical model used to simulate pile groups is accurate and capable of calculating the depth of sediment scour.

Research on Treatment Measures of Poor Geology of Bridge Pile Foundation of Deep Water and Bare Rock Geology

Research on Treatment Measures of Poor Geology of Bridge Pile Foundation of Deep Water and Bare Rock Geology

Settlement mechanism and improvement of thick silty sand layer overlying mud foundation

Many highways have been built on the eastern coast of China in the past decades. Recently, some engineering problems have emerged after long-term operation. Due to the different properties between the underlying soil and bridge pile foundations, the problem of bumping at the bridge head is inevitable. To study the potential causes and provide insight for future improvement, the settlement of typical highways in the Hangzhou Bay area, which had been open to traffic for more than 10 years, was investigated. After an analytical calculation with the verification of the numerical method and field data, it was indicated that long-term deformation was mainly caused by the poor properties of the lower of the two layers that make up the underlying soil. The trend of the variation of the lower layer keeps increasing at a slow rate during the construction period, resulting in sustained and rapid changes during the following years. Different kinds of ground improvement such as lightweight materials and soil–cement columns generated by deep mixing or jet grouting methods are discussed. The improvement of the lower layer will be more effective. With the analytical method, it is convenient and efficient to calculate and analyse the settlement at different periods, which is significant for design.

Condition Diagnosis of Long-Span Bridge Pile Foundations Based on the Spatial Correlation of High-Density Strain Measurement Points

Pile foundations of long-span bridges are often deeply buried in soil, and their structural condition is difficult to accurately diagnose by conventional methods. To address this issue, a method for diagnosing the structural condition of bridge pile foundations based on the spatial correlation of high-density strain measurement points is proposed. The strain data of the high-density measurement points of a bridge pile foundation are obtained by using distributed optical fiber sensing technology based on Brillouin scattering, and then an algorithm for diagnosing the structural condition of the pile foundation based on geographically weighted regression analysis is presented. On this basis, aiming at the scour of the pile foundation of long-span bridges, an algorithm for estimating the scour depth of the pile foundation based on sliding plane clustering is proposed. Finally, the effectiveness of the proposed method is verified by numerical simulation and actual bridge data.

Experimental Study on the Axial Compression Performance of an Underwater Concrete Pier Strengthened by Self-Stressed Anti-Washout Concrete and Segments.

Compared with the conventional drainage strengthening techniques, the precast concrete segment assembly strengthening method (PCSAM) is regarded as a fast, more economical, and traffic-friendly underwater strengthening method for damaged bridge piers and piles, as the drainage procedure can be omitted. However, this method still has some disadvantages, such as strength loss of the filling material, debonding of the interface due to shrinkage of the filling material, poor connection effects, and poor durability of the segment sleeves. To solve these problems, the PCSAM is improved in this study by using self-stressed anti-washout concrete (SSAWC) as the filling material and by developing a lining concrete segment sleeve (LCSS) by referring to the design theory for shield lining segments. Six specimens are designed and prepared with consideration of the influential factors, such as the self-stress, thickness of the filled concrete, and concrete strength of the LCSS, then the monotonic axial compression test is carried out to investigate the improvements in the axial compression properties of the specimens. Accordingly, extended parametric analyses are performed based on the established numerical models. Finally, the calculation formula for the bearing capacity is proposed based on the analysis results. The results indicate that the SSAWC can provide initial confining compressive stress in the core region of the piers, in addition to increasing the bearing capacity and ductility of the specimens. The improved LCSS segment connection is more reliable and increases the strengthening efficiency. The influence of self-stress on the bearing capacity of the specimens is cubic and the influence of the filled concrete strength on the bearing capacity of the specimens is nonlinear. The calculation formula for predicting the bearing capacity of axially compressed columns possesses good applicability and can be used as a reference for practical engineering.

Quality Problems and Control Measures of Highway Bridge Pile Foundation Construction

Quality Problems and Control Measures of Highway Bridge Pile Foundation Construction

Design optimization analysis of pile foundation parameters for widening bridge in cold region

Relying on Yunliang River Bridge of Beijing-Harbin expressway reconstruction and expansion project, the pile-soil interaction model is established by using ABAQUS. Based on the sensitivity analysis of the vertical deformation, cross-bridge deformation and additional bending moment of the old pile under different design parameters such as pile diameter and pile length, the influence of different design parameters of the new pile foundation on the additional internal force and deformation of the old pile is studied, which provides a theoretical basis for the construction of bridge pile foundation in cold areas.

Optimization of design parameters of displacement isolation piles constructed between a high-speed railway bridge and a double-line metro tunnel: From the view point of vibration isolation effect

A double-line metro tunnel was constructed beneath an existing high-speed railway bridge in a city of east China. To avoid the unexpected displacement of the bridge resulting from the shield tunneling, the displacement isolation piles were employed between the shield tunnels and the pile foundation of the bridge. An accompanied optimization design issue of the isolation piles is analyzed in this work. The optimization target is not only that the displacement criteria of the bridge pile foundation during tunneling process must be met, but also an outstanding vibration mitigation effect in operation process should be achieved. In this work, a steady-state finite element analysis (FEA) is employed to evaluate the limit of the pile spacing according to the displacement criteria of the high-speed bridge. After that an analytical model and a three-dimensional (3D) finite-infinite element model of the bridge-foundation-tunnel system are established, respectively, for further optimization of the pile parameters from the view point of vibration isolation effect. The optimized pile spacing of the isolation piles for the real project case is finally recommended based on in-situ measurement data and the evaluation results.

Analysis of the Influence of Train Dynamic Load on the Side-Crossing Bridge Pile Subway Tunnel

In order to explore the influence law of train dynamic load on the side-crossing bridge pile foundation subway tunnel, taking Xi’an Metro Line 14 underneath the Datong-Xi’an High-speed Railway Bridge Project as the background, three-dimensional finite element numerical simulations have been carried out on four working conditions: the subway tunnel shield is not constructed, the shield is constructed to the high-speed rail bridge, the subway right line tunnel is completed, and the subway tunnel is double-line completed. The analysis results show that the train dynamic load is transferred to the tunnel structure of 11.0m underground through the bridge, pile foundation and surrounding strata, the maximum position of the tunnel structure dynamic response is at the haunch, the response of the double-line tunnel is greater than that of the single-line tunnel; the train dynamic load has the greatest impact on the pile top of the bridge pile foundation and the least impact on the pile bottom; the subway tunnel adjacent to the bridge pile reduces the train dynamic response of the pile foundation, when there is no tunnel on the side of the pile foundation, the dynamic response of the bridge pile foundation is the largest, the single-line tunnel comes second, and it is the smallest when there is the double-line tunnel.

Environmental Engineering Deformation Control of High-speed Railway Shield Tunnel Under Crossing Bridge Piles

With the continuous acceleration of my country’s high-speed rail construction, it is inevitable to cross the existing engineering structure during the construction process. During the construction of high-speed railway, the control of the influence and deformation of the existing structure is a subject that needs to be studied in environmental engineering. Hangzhou metro line 1 is designed to cross under the Hu-Hang high-speed railway. According to the design, the shield tunnel is very close (minimum distance 5.19m) to the bridge piles of the Hu-Hang high-speed railway. Therefore, how to control the deformation of the bridge piles is a big problem in the shield tunnel excavation. Before construction, the method of the bored piles coupled with the jet grouting piles was proposed. The 3D numerical model was built to study the deformation of the bridge piles with the cases of the shield tunnel excavation without soil consolidation, the construction of the bored piles coupled with the jet grouting piles and the shield tunnel excavation with soil consolidation. The results show that the method of the bored piles coupled with the jet grouting piles can control the deformation of the bridge piles in the shield tunnel excavation effectively. Then, the deformation monitoring of the bridge piles was performed in the process of construction. The monitored data were close to the calculated results, which implies that the method of the bored piles coupled with the jet grouting piles is effective.