Pile Location Research Articles

Multi-Source Monitoring and Numerical Simulation Deformation on Highway Steep Slopes Under Rainfall Effects

Rainfall is one of the most important factors affecting slope stability. This study employed multi-source monitoring devices to observe the slope displacements in real time under rainfall infiltration and performed numerical simulations to investigate the effects of different rainfall conditions and anti-slip pile configurations on slope stability. Specifically, multi-source monitoring operations were conducted on the high and steep slopes along the Yunmao Expressway. Real-time data on slope deformation, rainfall, and displacement at the tops of anti-slip piles were collected and analyzed, and numerical simulations were conducted using Geo Studio finite-element software. The findings indicated that abrupt deformation of slopes occurs once a threshold rainfall amount is surpassed and sustained over a specific duration. Slope displacement decreased with increasing slope depth above the potential slip fracture surface, with a more rapid reduction in deformation rates observed in slopes reinforced with anti-slip piles. For equivalent rainfall amounts, short-duration, intense rainfalls led to a rapid decrease in the slope safety factor, which also recovered rapidly once the rainfall ceased, in contrast to long-duration, mild rainfalls. The presence and location of anti-slip piles significantly influenced slope stability; therefore, project implementation should carefully consider factors such as cost and duration for optimal decision making.

Analysis of hydrodynamic behavior in response to diverse pile arrangements adjacent to an impermeable dike

ABSTRACT Intense energy flow near the dike head significantly influences the development of the dike field zone (DFZ), momentum exchange zone (MEZ), and mainstream zone (MSZ), leading to potential partial or full failure of the dike in the MEZ. To address this, laboratory experiments were conducted to observe flow changes and rate of energy reduction around a single impermeable dike, with alterations made to the pile group length (HL: half-length = 11.5 cm and FL: full length = 23 cm), location (U: upstream, D: downstream), and shape (C: Circular, DV: Delta Van, ST: Streamlined tapered, APF: Angled Plate footing). Modifications in the MEZ flow structure were studied to mitigate concerns about intense energy vortices and dike head flows. These piles helped to assess factors like flow deflection, backwater rise, energy reduction rate, velocity fluctuations, and discharge distribution percentages across the zones. The data revealed that when the pile group length was increased from HL to FL, there was an inverse effect on depth-averaged velocity, MEZ discharge distribution percentage, and flow deflection toward the DFZ. Conversely, there was a direct influence on the rise in backwaters, rate of energy reduction, and discharge distribution percentages in the DFZ. The U-FL-APF pile dike showcased optimal results, displaying a reduction in maximum energy by 52% and streamwise velocity by 96%, while also increasing the backwater rise and discharge distribution by 22% and of only 5% in the MEZ, respectively, compared to a single impermeable dike. During flood events, these suggested measures can mitigate the intensified swirls formed in the DFZ, protect the dike head from direct momentum exchanges in the MEZ, and enhance flow deflection into the MSZ.

A Procedure to Characterize Wood Pile Inventories at Roadside

Tracking roadside wood inventories is necessary for wood procurement. However, this operation is increasingly problematic due to the costs associated with reaching remote sites, labour shortage, and the methods providing limited information on the characteristics of the logs required for transport planning. To overcome these problems, an automated procedure has been developed in Arcmap to characterize individual wood pile inventories at roadside by using GPS points of forwarders, harvester production files, and the road network shape files. An inventory of the logs in the harvest area followed by a wood pile inventory at the roadside were made to evaluate how the procedure could trace logs from machine operating trail to predicted wood pile locations. The study was done at six harvest blocks in the Saguenay-Lac-Saint-Jean region in the province of Quebec, Canada. The procedure was not able to differentiate individual wood piles and aggregated several piles into predicted unloading areas. Results indicated a similarity index of 72% to manually inventoried wood piles. The similarity index could be explained by the low percentage of inventoried unpredicted wood pile lengths (3%) and a high percentage of overpredicted wood pile lengths (27%). The positive allocation rate could not be assessed at the level of the individual piles. On the other hand, the procedure properly allocated 96% of the logs to unloading areas. With the level of precision obtained, the developed procedure could be beneficial for managing the transportation of wood at the level of the road segment since it provides all the dendrometric data of the logs available for transport without requiring human intervention in the forest.

A Vehicle-to-Grid planning framework incorporating electric vehicle user equilibrium and distribution network flexibility enhancement

The rapid surge in electric vehicle (EV) adoption, coupled with advancements in charging technologies, emphasizes the critical necessity for expanding EV recharging infrastructure. Simultaneously, the Distribution Network (DN) encounters escalating challenges in meeting charging demand during peak traffic periods. Consequently, there is a mounting demand for the deployment of innovative Vehicle-to-Grid (V2G) technologies to augment the DN’s flexibility in power dispatch and alleviate travel costs for EV users. Hence, this paper proposes an EV-user-equilibrium-(UE)-constrained V2G planning framework that enhances flexibility in the DN. The framework aims to ascertain the optimal placement and capacity of EV charging stations (EVCSs) and V2G charging piles within the Transportation Network (TN). It takes into account the equilibrium condition stemming from competitive EV charging and routing behaviors alongside the optimal expansion of DN energy resources to accommodate the electricity supplied by the V2G piles. This study commences by analyzing EV drivers’ travel decisions, considering the influence of charging and V2G pile locations and sizes. Subsequently, we tackle the Traffic Assignment Problem with User Equilibrium (TAP-UE) model to characterize the steady-state traffic flow distribution of EVs. Following this, we formulate the optimization model for the Coordinated Power and Transportation Network (CPTN), which encompasses the optimal expansion of DN facilities and traffic flow regulation under UE conditions. To mitigate the computational complexity associated with the V2G planning model, we introduce a series of linearization methods to obtain a manageable Mixed-Integer Linear Programming (MILP) solution. Finally, to validate the efficacy of our proposed planning framework, we apply it to two test systems, including a real-world case study. Through these case studies, we explore the necessity and potential benefits of V2G technologies.

Research on disturbance influence of goaf residual deformation on simply supported beam bridge

In order to analyze the stability of the bridge above the goaf, the disturbance influence of goaf residual deformation on the bridge is studied. Firstly, an equivalent numerical simulation method of goaf residual deformation evolution process is studied by quantitative analysis the sensitivity of residual subsidence to the rock parameters using the OAT (one-variable-at-a-time). Then, the collaborative deformation of ground, pile, and bridge floor is studied under the condition of a simply-supported beam bridge above the goaf center. Finally, the mechanism of collaborative deformation of ground, pile, and bridge floor is revealed. The results show that the goaf residual deformation process can be obtained by weakening the elastic modulus of fractured rock in the caving zone. At the final residual deformation stage, the subsidence ratio of ground to pile is about 10, and the subsidence ratio of pile to bridge floor is about 2, while the ground horizontal movement ratio of ground to pile is about 7, and the bridge floor horizontal movement can be ignored. The bridge floor is always in the positive curvature influence zone, and the pile has an inhibitory effect on the curvature deformation of the bridge floor. The compression deformation occurs between the piles locations, while the tensile deformation occurs at the pile location. The evolution of negative frictional resistance derived from goaf residual deformation is the main reason for the change in the collaborative deformation law among the ground, pile and bridge floor. This research can provide scientific support and theoretical basis for the design, construction, and protection of the bridge above the goaf center, and can also provide reference for the stability evaluation of bridge above goaf under other conditions.

Development of Automatic Object Detection and IoT for Garbage Pickup Assignment Problem

Waste management remains a challenge in certain cities, particularly in allocating fleets responsible for collecting garbage from temporary disposal sites. Inadequate planning can lead to the accumulation of substantial waste piles. This study aims to enhance truck assignment by considering truck capacity and the collection route. The assignment process incorporates the fundamental concept of the transportation problem, precisely the northwest corner method. The volume of waste transported aligns with the resident or industrial population within the designated service area. The waste generation capacity determines the future fleet and quantity, forming a crucial element of the ensuing distribution channel. A monitoring system integrating object detection and the Internet of Things (IoT) has been devised to ensure effective garbage collection. Cameras strategically positioned at temporary disposal sites transmit real-time images. The system evaluates garbage collection capacity through object detection facilitated by neural network training. The research outcomes demonstrate the system's capability to identify waste pile levels and validate the garbage pickup process by the designated fleet. Future research should focus on assignment and scheduling in waste transportation, enabling fleet allocation within specific timeframes. Additionally, an object detection algorithm refinement is necessary for more precise identification of waste pile locations.

Experimental Evaluation of Optimizing Sheet Pile Installation Depth and Distance to Mitigate Liquefaction-Induced Foundation Settlements

Liquefaction-induced settlement poses significant challenges to the stability and performance of structures constructed on liquefiable soils during seismic events. To mitigate the adverse effects of liquefaction-induced foundation settlements, sheet piles are utilized to provide lateral confinement to the soil, thereby enhancing its stability. The performance of sheet piles is contingent upon their installation location. Therefore, identifying the optimal installation location for sheet piles remains a topic of interest. This research aims to evaluate the optimal installation location of sheet piles to mitigate liquefaction-induced foundation settlements. The experimental study employs a moderate scale 1g shaking table to replicate seismic events and investigate the behavior of sandy soil under liquefaction conditions. Multiple configurations of sheet piles, varying in terms of distance from the foundation, depth within the dense layer, and effect of thickness are examined. The excess pore water pressure generation and dissipation, and foundation movement (settlement and tilting) are used to determine the optimal location of sheet piles that minimize liquefaction-induced foundation settlements. The results indicate that the liquefaction-induced foundation settlement increased with increasing the distance between the sheet piles and the foundation. Adversely, the settlement decreased with increasing the embedment depth of sheet piles. Additionally, although this was not the focus of this study, the installation of thinner sheet piles surrounding the foundation appeared to be a more effective measure than thicker sheet piles in mitigating liquefaction-induced foundation settlements based on this experiment.

Performance of unequal piled raft under vertical loading in cohesionless medium

The performance of piled rafts with unequal pile lengths in cohesionless soil under vertical loading was investigated in the present study through experimental and numerical analysis. A pattern function is used to define the pile length arrangement. The motivation for considering such a function is to ensure that the varying pile lengths follow a suitable geometric pattern, and it does not obstruct the construction practice in field applications. The piles at different locations within the raft were equipped with strain gauges to observe the strain distribution along their lengths during the static load test. Load sharing was evaluated by placing an earth pressure cell beneath the raft. A three-dimensional finite element analysis was used to simulate the experimental results aimed at assessing the load settlement and load-sharing responses. A comparison was conducted to verify the reliability of the tests. Subsequently, a detailed parametric study was conducted in accordance with different pattern functions, pile spacing, and pile locations in the piled rafts. The load settlement, load sharing, and bending moment of the raft were evaluated. An understanding of the pile behavior at different locations within the group will be helpful in selecting the suitable pile geometry during actual construction in the field. A foundation designed by considering the optimized pile length will be helpful in developing a more economical and resilient foundation system.

Pseudo-static analysis of 3D unsaturated bench slopes stabilized by multiple rows of piles

Bench slopes incorporated with multiple rows of anti-slide piles remain an effective technique in landslide disaster preventions and are widely employed in the design of new subgrades and embankments. To provide more realistic results for engineering guidance, the three-dimensional (3D) effect and suction in soils require explicit considerations. Employing the upper bound limit analysis method, a 3D limit analysis of bench slopes stabilized by multiple rows of piles is performed in this paper. The upper bound solutions of several illustrative slopes are optimized and compared with the published ones, indicating the validity of the optimization program and the proposed method. A series of parameter analyses are conducted regarding the roles of suction and anti-slide piles in slope safety assessments. The results show that the suction effect and pile reinforcement increase continually as the pile location increases and the influence of bench width can be ignored. The stability of bench slopes stabilized by multiple rows of piles differ with that of slopes stabilized by single row of piles dramatically. The maximum pile reinforcement reaches 70% for sandy soil slopes but only 30% for clayey soil slopes. The influences of surcharge load and seismic load on the pile reinforcement can nearly be neglected.

Developing Tree-Based Machine Learning Models for Estimating the Pile Setup Parameter for Clay Soils

Piles driven into cohesive soils usually experience increases in capacity with time, known as pile setup phenomenon. Several empirical methods have been developed to estimate the setup parameter (A), such as the well-known Skov and Denver equation. Parameter A is crucial in predicting pile setup behavior. In this study, tree-based machine learning (ML) models such as random forest (RF) and gradient boosted tree (GBT) were applied for better estimation of the setup parameter. A database consisting of setup data from 12 instrumented piles tested at different times, and corresponding cone penetration test (CPT) and soil boring data were collected. The soil properties (i.e., undrained shear strength, plasticity index, over consolidation ratio, and coefficient of consolidation) and CPT data (cone tip resistance, sleeve friction) of clayey soil layers at pile locations were utilized to develop the ML models. Three types of tree-based ML model were developed for predicting the setup parameter, A, using CPT and soil boring data. A comparison was made between the developed ML models based on soil properties, ML models based on CPT data, and an artificial neural network (ANN) model proposed in a previous study using the same dataset. Furthermore, the best performing ML models were compared with two nonlinear regression models recommended in a previous study using the same dataset for estimating the setup parameter. The results of this research clearly demonstrated the superior prediction capability of the tree-based ML models, particularly the GBT model over the ANN and the two nonlinear regression models in evaluating the pile setup parameter.

Probabilistic pile reinforced slope stability analysis using load transfer factor considering anisotropy of soil cohesion

AbstractA probabilistic limit equilibrium framework combining empirical load transfer factor and anisotropy of soil cohesion is developed to conduct pile‐reinforced slope reliability analysis. The anisotropy of soil cohesion is determined conditioned on that the thrust force direction is parallel to the major principal direction and it is easily combined with load transfer factor, which are related with soil parameters, and pile parameters. The proposed method is illustrated against a homogeneous soil slope. The sensitivity studies of pile parameters on factor of safety (FS; calculated at respective means of soil parameters) and β demonstrated that the anisotropy of soil cohesion tends to pose significant effect on reliability index β than on FS. The effect of anisotropy of soil cohesion on FS is found to be slightly different under different pile locations, whereas its effect on β is observed to be least if piles are drilled at the middle part of slope and more significant effect is observed when piles are drilled at the lower and upper part of slope. The plots from the sensitivity studies provide an alternative tool for pile designs aiming at the target reliability index β. The proposed method contributes to the pile‐reinforced slope stability within limit equilibrium framework.

Assessment of emissions and potential occupational exposure to carbon monoxide during biowaste composting.

To date, only a few studies focused on the carbon monoxide (CO) production during waste composting; all targeted on CO inside piles. Here, the CO net emissions from compost piles and the assessment of worker's occupational risk of exposure to CO at large-scale composting plants are shown for the first time. CO net emissions were measured at two plants processing green waste, sewage sludge, or undersize fraction of municipal solid waste. Effects of the location of piles (hermetised hall vs. open yard) and turning (before vs. after) were studied. Higher CO net emission rates were observed from piles located in a closed hall. The average CO flux before turning was 23.25 and 0.60 mg‧m-2‧h-1 for hermetised and open piles, respectively, while after- 69.38 and 5.11 mg‧m-2‧h-1. The maximum CO net emissions occurred after the compost was turned (1.7x to 13.7x higher than before turning). The top sections of hermetised piles had greater CO emissions compared to sides. Additionally, 5% of measurement points of hermetised piles switched to 'CO sinks'. The 1-h concentration in hermetised composting hall can reach max. ~50 mg CO∙m-3 before turning, and >115 mg CO∙m-3 after, exceeding the WHO thresholds for a 1-h and 15-min exposures, respectively.

A novel framework for ascertaining the safety factor and critical slip surface of 3D slopes reinforced with piles

The pile is a widely used reinforcement device in geotechnical engineering. For the present paper, we propose a new solution for calculating the safety factor (SF) of the 3D slope reinforced with piles and determining the critical slip surface (CSS) in the framework of minimum potential energy method. In particular, the mobilized shear stress on failure surface is determined by the equilibrium equation of forces operating on slip body. Meanwhile, the moving direction of 3D slope is equivalent to the direction of combined force acting on slip body. Additionally, the present method is combined with the genetic algorithm to identify CSS, and a novel criterion is proposed to locate the shape and position of CSS of a 3D slope using the total potential energy of landslide system as the objective function. The validation and comparison of results indicate that the SF obtained by the introduced method are close to reference solutions, and SF shows an obvious negative correlation with sliding direction (SD). It is also found that the support effect of pile is related to the pile location and the pile density. Meanwhile, the optimal pile position depends on the shape of failure surface and shear strength parameter of soil. Moreover, the effects of some parameters on SD of 3D slopes reinforced with piles are also studied.

Influence of deep excavation on behavior of adjacent single pile: effect of pile location

Influence of deep excavation on behavior of adjacent single pile: effect of pile location

Seepage Quantity Analysis Beneath Concrete Dams with Various Sheet Piles using Different Numerical Models

Seepage is a dangerous phenomenon under hydraulic structures and the main cause of failure and damage to dams when neglected and not processed. This study evaluates the numerical effects of the sheet piles' quantity, depth, and spacing beneath a concrete dam with isotropic and homogenous foundations on the seepage rate, pressure head, and exit gradient. The solutions were obtained using SEEP/W code in GeoStudio software 2018 for three configurations using single, double, and triple sheet piles. In addition, SLIDE software 6.02 was examined using single and double sheet piles. Dimensional analysis was applied to draw the dimensionless variables that affect the seepage rate and exit gradient, and all tests were repeated for three different sheet pile depths and distances from the heel of the dam. The findings showed that the seepage rate in all studied configurations reduced when sheet pile depth increased. The position of the sheet pile from the dam's toe significantly decreased the seepage rate in cases using single and double sheet piles, while in cases using three-sheet piles, the position of the middle sheet pile insignificant decreased seepage. It was recognized that when using a single sheet pile, the drop in pressure head increased with depths when the sheet pile was located at the heel and middle of the dam. In addition, in the case of a single sheet pile at the toe or using two and three-sheet piles, the pressure drop decreased as the depths increased. Also, the results showed that the middle sheet pile location in the case of three sheet piles slightly affected pressure reduction. Furthermore, the results showed that using two and three-sheet piles was more effective than using a single one in reducing the exit gradient, while the position of the middle one in the case of using three-sheet piles was insignificant. A nonlinear empirical equation was developed using SPSS 22 program, and the comparison of the seepage rate measured by SEEP/W and SLIDE software versus its quantity calculated from empirical equations showed a good agreement as the determinations (R2) coefficients were equal to 0.9779 and 0.9928, respectively.

Prediction of single pile response to lateral soil movement in model test

An analytical approach is presented for predicting the response of the pile by lateral soil movement in a model test in terms of the two-stage procedure. The prescribed lateral soil movements with inverse triangular, uniform, and arched profiles are examined in the analysis. The free-field displacement is obtained explicitly by the elasticity and Fourier expansion technique. The soil–pile interaction is considered for the response of the pile under soil movement in light of the theory of a beam on the Winkler foundation. Parametric studies are performed to investigate the effects of the soil–pile system and the loading conditions on the response of the pile. The free-field displacement attenuates quickly with its distance to the loading block. The pile response under lateral soil movement in the model test is greatly dependent on the pile location and the loading conditions. For the pile with a free tip, the deflection and bending moment of the shaft are relative to the restraint condition at the top. The effect of the pile-soil stiffness ratio is not great on the deflection of the pile but significant on the bending moment of the shaft.

Assessment of Small Diameter Steel Pile as a Stabilizing Element for Transmission Tower Slope Stability

Background: Stabilization of unstable slopes with relatively large reinforced concrete piles has been widely adopted over the past several decades. Small diameter steel piles have several advantages as a slope reinforcement technique for an unstable transmission tower slope where space and access restrictions that typically occur render alternate approaches unfeasible. Methods: In this study, a numerical performance assessment of small diameter steel pile as a stabilizing element for transmission tower slope stability was carried out using an uncoupled analysis, in which the pile response and slope stability are considered separately. Numerical evaluations are presented and the influencing parameters that could affect the behavior of reinforcing piles to increase transmission tower slope stability are investigated. Results: The numerical analysis results indicate that the soil properties, slope geometry, pile location, pile diameter, pile length and number of pile rows have a combined effect on the performance of small diameter steel piles to stabilize transmission tower slopes. Conclusion: The numerical assessment can satisfactorily capture some fundamental response of transmission tower slope reinforced with multi-row small diameter steel piles.

A system for inspecting karst voids during construction of cast-in-place pile foundations

Karst voids at pile locations are highly adverse to the bearing capacity and construction safety of cast-in-place pile foundations. This study developed an inspection system prototype of karst voids during cast-in-place pile foundation construction. The system consists of a multifrequency borehole sonic probe, two pile hole sonar probes, an in situ computer, and a corresponding signal analysis method. Borehole and pile hole detection are conducted during the investigation and pile hole drilling to inspect karst voids around the borehole and beneath the bottom of the pile hole. The analysis of the synthetic data verifies the effectiveness of the proposed method. A field inspection of karst voids during cast-in-place pile foundation construction was conducted. Comprehensive geophysical methods, including borehole optical imaging, 3D laser scanning, and borehole logging were deployed for comparison. The results show that the system can provide detailed geological information to the design of piles and ensure the construction safety of foundations.

Mathematical Modeling for Distribution Optimization of Senior High School Telephone Booths

Due to the policy of the Ministry of Education, many senior high schools in China have constructed some telephone booths. However, the survey found that the distribution of telephone booths in senior high school is irrational. Previous studies focused on the humanized design of telephone booths and the 0-1 planning optimization of charging pile location, but there were few studies on optimizing the distribution of phone booths in campus. It is necessary to optimize the distribution of telephone booths in senior high schools to facilitate students' life and save students' time. In this paper, Qingdao No. 2 Middle School in Shandong Province is taken as an example. Firstly, according to the previous research on 0-1 programming model, the number of people and demand in the distribution area of telephone booths in the campus are scored, and the scoring matrix is formed. Then 0-1 programming modeling was carried out and solved with Matlab. Finally, the optimal construction point to be built is obtained.

Parametric study of embankment stabilization by pile reinforcement

Stabilising piles have been proven as an effective slope stabilization approach. This study aims to investigate the optimal location of stabilising pile for an embankment slope with a surcharge loading at crest. A series of finite element analyses were performed to determine the optimal location of the pile with considerations of varying slope gradients. An additional analysis was performed to compare the factor of safety computed from the present 2D analysis with the previous 3D analysis. The results showed that the introduction of the stabilising pile could effectively minimise the deformed soil mass and slip surface, with the greatest improvement recorded for the embankment of 1.5V:1H gradient. The optimal pile location was found to be at the middle of the slope. The pile influence zone (Wpile ) obtained from the present numerical study showed reasonably good agreement with previous results of centrifuge experiments. Based on the comparison of factor of safety computed from the present 2D analysis with a previous 3D analysis, the 2D analysis generally yielded a more conservative FOS (about 20% lower) than the more rigorous 3D analysis because of the absence of soil arching effect. As conclusions, it is recommended to install piles at the middle of slope to yield the most favourable slope stabilization effect. A simple 2D analysis can be used to analyse the problem of pile stabilised embankment with a slightly more conservative FOS was expected than the rigorous 3D analysis.