Ground Anchors Research Articles

Simulation case study of precise orbit determination for IGSO satellites using onboard Ka/GNSS observations

Abstract Inter-satellite links can provide a more accurate space reference for IGSO satellites than onboard GNSS side-lobe signals. In this study, POD quality is analyzed based on onboard Ka/GNSS observations by utilizing a simulated IGSO satellite orbit. Considering the similar orbit altitude, we first select three IGSO satellites from BDS-3 as target satellites. These satellites have actual Ka-band measurements available, along with other BDS-3 satellites and ground anchor stations, allowing us to assess the POD performance. The Ka-band availability of these IGSO satellites can serve as a means to evaluate the maximum utilization of BDS Ka-band resources. In terms of the POD results, the root mean square (RMS) of the Ka-band residuals can reach 10.9 cm, and the orbit consistency in the 3D direction is better than 0.35 m. In addition, simulations are conducted for onboard GNSS, inter-satellite link (ISL), and ground anchor-satellite link (GSL), considering the different constraints on the Ka-band resources. With only GNSS measurements, the 3D orbit accuracy is approximately 1.5 m, but when additional ISL and GSL measurements are considered, the POD accuracy can surpass 0.28 m. These results illustrate that incorporating Ka-band measurements can effectively enhance the POD accuracy for high-orbit satellites.

Numerical analysis of the displacement of retaining wall in the Carpathian flysch region

This paper presents a numerical analysis of the displacement of the substructure for the construction of the S1 route bypassing Węgierska Górka. The numerical analysis includes displacement calculations taking into account the ground anchor stiffness obtained in acceptance tests. The results of the analysis were compared with monitoring measurements. A sensitivity analysis was carried out in relation to the soil parameters used and the achieved ground anchor stiffnesses

Technical Advantage and economic analysis of spiral anchor foundation in desert area

State grid corporation “Infrastructure Technology [2022] No.14”document spiral anchor application as a recommended application of technology, requirements for the application of engineering as far as possible, since then, spiral Anchor Foundation is widely used in tower foundation of transmission line engineering. Using desert, Gobi, desert and abandoned mines to build photovoltaic power plants has become the“14th five-year plan” new energy development priority, supporting the rapid development of power grid transmission projects, there are more and more overhead power lines across the desert. Compared with other types of foundation, spiral anchor foundation in desert area not only has higher feasibility in technology, but also has more obvious advantages in material consumption and environmental protection, in particular, it can realize the advantages of zero-concrete and zero-earthwork construction, greatly saving the project cost.

Ultimate Capacity and Load Transfer Mechanism of Ground Anchors in Granular Soils: State-of-the-Art

The grouted ground anchor is the most used geotechnical element to transfer the tension load from the superstructure or the soil mass in front of the potential failure surface (active zone) to a deeper, efficient soil layer for its reliability and feasibility. It was originally constructed by inserting the tendon, usually a steel strand, into an already drilled borehole filled with cement grout. It was successfully used in the Cheurfas dam in Algeria in (1934). According to the load transfer mechanism, there are two types of ground anchors: tension-type and compression-type. The names of these two types of anchors refer to the developed stresses in the grouted body. The present work presents a literature survey about the load transfer mechanism for both types of anchors: tension and compression embedded in granular soil. Many factors affecting the load transfer mechanism have been reviewed. The main factor affecting the load transfer mechanism is the confining pressure of the borehole. The recently developed methods of estimating the ultimate pullout capacity of the anchor have been reviewed and discussed.

Study on the influence of cap connection mode on the deformation of all-steel spiral anchor

Abstract Spiral anchors find widespread use across diverse projects, including residential, commercial, street lamp poles, photovoltaic systems, and transmission tower infrastructure, due to their simple structure, convenient construction, high degree of mechanization, and minimal soil disturbance. All-steel spiral anchors offer notable advantages in terms of ease and environmental friendliness. To bolster their utilization in power transmission engineering applications, based on the application requirements of the spiral anchor foundation of the Weifang Guanting transmission tower, the influence of the connection method of the bearing platform on the deformation of the all-steel spiral anchor is studied. The results show that both the welding and bolt connection methods can meet the required stiffness of the project.

Spatial Variability of Sliding Plane on Volcanic Region. Case Study of Sta 21+200 Cisumdawu Toll Road

Landslide can be caused either by natural phenomenon or due to human intervention. Regardless of the triggering factor, once landslide occurs, sliding plane in the form of discontinuity or sometimes referred as sliding plane is formed. Identifying the location and geometry of the sliding plane is important in determining the location of the reinforcement to rehabilitate slope failure. However, it is often difficult to locate the location and geometry of the sliding plane as the sliding direction is also difficult to ascertain. In this paper, slope failure which occurred in STA 21+200 of Cisumdawu toll road is used as case study. Variability of the sliding planes are investigated based on the location of the concrete overbreak that occurred during the bored pile construction on Tuff (volcanic soils) in Sumedang Region. Sliding planes are also estimated based on the soil investigation and pile boring records. The proposed solution is to reinforce the bored piles that did not penetrate into the hard layer with ground anchors installed at the pile cap.

Experimental and Numerical Analysis of an Innovative Combined String–Cable Bridge

Suspension bridges, such as stress-ribbon, are among the simplest structural bridge systems and have the lowest structural height. The flexibility of these elegant bridges poses great challenges for designers to minimize their deformability under asymmetrical operational loads. Due to the small initial sag, such load-bearing structures also cause significant tensile forces, which requires them to have large cross-sections and massive anchor foundations. This paper analyzes an innovative suspension steel bridge structure combined with a string and a cable. More attention is paid to asymmetric loading as this is more relevant for suspension structures. The new structure is studied numerically and experimentally. It is established that the string stabilizes the displacements of the bridge under asymmetric loading. The stabilization efficiency is proportional to the value of the pre-tension force of the string. The obtained results reveal the behavior of the structure and enable an evaluation of the accuracy of the numerical results, as well as the applied modeling. In addition, the experimentally obtained results allow the evaluation of more aspects of the behavior of the new bridge, which will be useful in further studies of this type of structures.

A stacking machine learning model for predicting pullout capacity of small ground anchors

Small ground anchors are widely used to fix securing tents in disaster relief efforts. Given the urgent nature of rescue operations, it is crucial to obtain prompt and accurate estimations of their pullout capacity. In this study, a stacking machine learning (ML) model is developed for the rapid estimation of pullout capacity offered by small ground anchors used for temporary tents, leveraging cone penetration data. The proposed stacking model incorporates three ML algorithms as the base regression models: K-nearest neighbors (KNN), support vector regression (SVR), and extreme gradient boosting (XGBoost). A dataset comprising 119 in-situ anchor pullout tests, where the cone penetration data were measured, is utilized to train and assess the stacking model performance. Three metrics, i.e., coefficient of determination (R2), mean absolute error (MAE), and root mean square error (RMSE), are employed to evaluate the predictive accuracy of the proposed model and compare its performance against four popular ML models and an empirical formula to highlight the advantages of the proposed stacking approach. The results affirm that the proposed stacking model outperforms other ML models and the empirical approach as achieving higher R2 and lower MAE and RMSE and more predicted data points falling within 20% error line. Thus, the proposed stacking model holds promising potential as a solution for efficiently predicting the pullout capacity of small ground anchors.

Experimental and data-driven prediction for the impact of free/bond lengths of element specimen on interface characterization of ground anchors

The performance of ground anchor often employed in retaining the stability of onshore structures depends largely on its interface shear behavior. Interface characterization using pullout tests on element specimens of ground anchor is a versatile approach for determining its interface shear behavior. This research combines laboratory experiments and data-driven modeling to investigate the effect of free/bond lengths as a critical configuration condition of element specimen on the interface characterization results of ground anchors. Machine Learning models such as back propagation neural network (BPNN), random forest (RF), and support vector regression (SVR) were employed. Moreover, the particle swarm optimization (PSO) algorithm was used to improve the process. The results indicate that variations in free/bond lengths have a negligible effect on the trends of interface bond curves when bond lengths reach 90–100 mm. Moreover, when the bond and free lengths are set to 80 mm and 20 mm, respectively, the configuration conditions of the element specimen have a limited effect on the average interface shear strength. The PSO-BPNN model provided the most accurate predictions, which closely followed the experimental results compared to RF and SVR models. Compared to the other models, it reached a greater correlation coefficient (0.9975) and a lower root-mean-square error (14.89 kPa). Moreover, Partial dependence plot (PDP) is introduced to visualize the established machine learning model.

The Behavior of Horizontal Anchor Foundations Embedded in Sand under Uplift and Lateral Loads

The Behavior of Horizontal Anchor Foundations Embedded in Sand under Uplift and Lateral Loads

Experimental and numerical studies on the displacement and load-transfer mechanism of pile-caisson composite structure

The pile-caisson composite structure (PCCS) is an innovative underground anchorage foundation used to support large-span suspension bridges. This paper presents the displacement and the load transfer mechanism of the PCCS. The bearing responses of each individual pile in the PCCS were analyzed employing the finite element method, which was verified by the model test results. The peak bending moments borne by pile P11 and pile P53 in the PCCS exhibit the most significant disparity, with a difference that can reach up to 133.97%. Moreover, a parametric study utilizing numerical simulations indicates that augmenting the pile diameter and length, while reducing the pile spacing, can mitigate the displacements of the PCCS. However, there is an upper limit (i.e. S = 3.5d) for the pile spacing beyond which marginal benefits could be obtained. The findings of this study can provide guidance for the design and construction of the PCCS.

Study on the Principle of Cost Calculation and Economy of Steel Screw Anchors

With the popularization of mechanized construction of transmission line engineering and the improvement of environmental water protection requirements, some new foundations have been popularized, and have great advantages. The steel spiral anchor foundation has the advantages of short construction period, quick mechanization construction speed, and zero concrete and zero earthwork construction. According to the construction process and test requirements of steel screw anchor, the principle of calculating the construction and test cost of steel screw anchor is put forward, the economic critical point of steel screw anchor is obtained.

Effect of the aquaculture on the seagrass Posidonia oceanica: a decade before and after in the Aegean Sea

Seagrass Posidonia oceanica is an endemic and a keystone marine plant in the Mediterranean Sea. It has been a decline in the distribution of P. oceanica meadows by several anthropogenic pressures (i.e. pollution, marine transportation, intensive coastal use, overfishing by ground scanning methods, anchors, aquaculture activities, alien and invasive species, overgrazing, tourist activities). The aim of this study, to evaluate impact of a fish farm in a island (Kızkulesi Island, Dikili, İzmir) on the seagrass Posidonia oceanica meadow from the Aegean coasts of Türkiye. Sampling was made in 2014 September and 2023 October between 0 and 30 m depth by scuba diving. P. oceanica meadow has been completely lost in a decade in the research site.

Bearing capacity analysis and mechanism study of shared caisson under multidirectional loading

Shared anchor foundations experience loads from various directions throughout their operational lifespan. As a result of environmental loads or the possibility of anchor chain failures, the loading direction of the shared foundation may alter, affecting its normal functionality. This study investigates the bearing capacity of the shared caisson in sand using an advanced model and numerical methods under multidirectional loading. Moreover, the research investigates soil responses to clarify the mechanisms governing bearing capacity. The study delves into factors such as load angles, sand density, and previous load magnitudes to comprehend their impact on the bearing capacity of shared caissons. The findings suggest that subsequent loading on dense soil enhances bearing capacity, whereas loading on loose soil reduces it. Key factors influencing the shared caisson's bearing capacity include plastic deformation of the surrounding soil and density changes resulting from previous loads. A coefficient was proposed for designing the shared caisson, taking into account multidirectional loads, thereby providing insights for future shared anchor foundation designs.

Response of anchor foundations in geogrid reinforced sand under combined loads

The use of geogrid reinforcement has proven to be an effective measure to improve the anchor uplift capacity. However, previous studies are limited to analyzing the axial pullout capacity of plate anchors. In comparison, the anchor foundations employed in field are compelled to resist both uplift and lateral forces. In most cases, the foundation's safety against lateral forces dictates the design criteria for tall structures. Therefore, improving the foundation's lateral load-bearing capacity is of utmost importance. This paper presents a three-dimensional numerical analysis of anchor foundations in geogrid-reinforced sand under uplift and lateral forces. The results highlight the benefits of geogrid reinforcement on the anchor's response to uplift and lateral loads. The geogrid reinforcement is modelled using cable elements capturing the actual apertures responsible for tensile force mobilization along the geogrid ribs. A significant reduction in the displacements of the anchor foundation is observed in geogrid-reinforced sand, both in horizontal and vertical directions, when combined loads are applied on the anchor. However, the maximum reduction is found in the case of vertical uplift forces for higher values of the applied load. The practical implication of this study is demonstrated using a performance-based design example of transmission tower foundations in geogrid-reinforced sand.

Geotechnical Practice of Construction on Unstable Slopes

The construction of facilities for various purposes in rugged areas in cramped urban conditions for builders is the main problem associated with solving geotechnical tasks of providing both the slope itself and buildings and structures of the surrounding development in the zone of geotechnical influence. Questions arise regarding the need to develop buried retaining structures. The article considers a case from the geotechnical practice of installing retaining structures using bored piles with diameters of 600 mm and 800 mm and ground anchors arranged using electric discharge technology (ERT anchors).

ПРОЕКТИРОВАНИЕ ГРУНТОВЫХ АНКЕРОВ. УЧЕТ ТОРЦЕВОГО СОПРОТИВЛЕНИЯ УШИРЕНИЯ ГРУНТОВОГО АНКЕРА ПРИ РАСЧЕТЕ ЕГО НЕСУЩЕЙ СПОСОБНОСТИ ПО ГРУНТУ.

Currently, ground grouted anchor systems are widespread in geotechnical construction. One of the stages of anchor system designs is ultimate load-holding (bearing) capacity calculation. To date, a clear methodology for calculation the bearing capacity of a ground anchor is not presented by the current regulatory documents. On the other hand, the existing calculation methods for determining the bearing capacity of the anchor (which are presented in SP 381.1325800, VSN 506-88, TSN-50-302-2004 and others) do not take into account all geometric parameters and technological factors. Therefore, the results of determination bearing capacity are significantly lower than the actual ones. Also, the calculation of the bearing capacity is reduced to determination the lateral surface resistance of the anchor’s cylindrical body only. An end-bearing resistance component of the fixed anchor is not taken into account by calculation. This article raises the issue of reliable determination of the ground grouted anchor’s calculated bearing capacity, taking into account all geometric and technological factors, and also considers the stress-strain state of soil and the destruction mechanics.

Pemodelan Numerikal Kestabilan Lereng Galian Abutment Jembatan pada Ruas Jalan Tol Bogor – Ciawi – Sukabumi

The Cikereteg Bridge is one of the infrastructures on the Bogor-Ciawi-Sukabumi Toll Road. Based on drilling data, it is recognized that the groundwater level is high and that the slope under the bridge has soil with a low standard penetration tests value (N-SPT) of less than 10. Hence, the stability of the slope is called into doubt. In order to strengthen slope stability under the bridge, this research will investigate slope stability while taking seismic loads into account and offer options for efficient slope reinforcement. By using the PLAXIS 2D software, the finite element method was used to analyze slope stability. The outcomes of the modelling suggest that the slope may not be stable, since it does not fulfill the design slope criteria, which are 1.8 for static conditions and 1.5 for earthquake situations. Respectively, the safety factor value is 1.396 for static condition and 1.068 when given an earthquake load. The design reinforcement model's results highlight that the subdrain reinforcement in combination with bored piles and ground anchors can fulfill the criteria for the slope of the bridge plan.

Probabilistic assessment of anchor foundation for transmission tower using multivariate adaptive regression splines

ABSTRACT This paper pertains to the reliability analysis of transmission tower foundations under variable wind loads. The reliability analysis of the anchor foundation, frequently employed for transmission towers due to their huge uplift capacity at shallow depth, is presented using a systematic probabilistic approach. The paper presents the design of an anchor foundation for a typical transmission tower based on loads obtained by applying lateral wind velocity on the tower. The Multivariate Adaptive Regression Splines (MARS) surrogate model is first developed to construct a deterministic prediction model for the anchor uplift capacity. The developed model is further used in the reliability analysis of the anchor foundation considering variabilities in the soil properties and the uplift load, and the results of the probabilistic analysis are reported in the paper. The results indicate the importance of incorporating variability in design variables for the proper safety of the structure. Soil cohesion is found to be the most sensitive parameter in the uplift capacity of the tower foundation. The comparison of the deterministic factor of safety and failure probability of the foundation brings out the importance of the reliability-based design methodology.

Installation performance of torpedo anchor at different installation heights under the action of currents: The example of T98 torpedo anchor

The deep-sea torpedo anchor is an innovative and cost-effective anchorage foundation. However, marine environmental loads such as currents have a significant impact on the free-fall installation of torpedo anchors in water, often leading to the failure of installation due to excessive inclination or large deviations from the installation location. Therefore, taking the T98 torpedo anchor commonly used in practical engineering as an example, this paper systematically investigates its installation characteristics under the action of currents. First, based on OpenFOAM®, a 3D numerical model is established to simulate the underwater falling process of torpedo anchors via dynamic model analysis method. Using the validated model, the influence of currents on the installation performance of torpedo anchors is then explored. Based on the findings, the installation conditions of T98 anchors at different installation heights are recommended. Finally, a semi-empirical method for estimating the anchor inclination and deviation of torpedo anchors under current action is proposed, which may facilitate the assessment of installation inclination and determine the installation release point of torpedo anchors.