Search

On 3 October 2013, a global failure occurred in one of the stabilised sections of a deep excavation in Shahrak-e gharb in Tehran. The excavation was supported by ground anchors with enlarged reinforced concrete thrust blocks and sprayed concrete facing. The failure occurred despite the system passing conventional limit equilibrium design and satisfying requirements in terms of allowable displacements. The case of Shahrak-e gharb was modelled using Abaqus in order to understand the soil deformation leading to the failure condition. It was found that a near-surface zone of weaker fill material was responsible for the failure. As the displacements during construction and the soil failure mechanisms were well matched by the numerical model, the case study was considered to be a validation case for the numerical model and a parametric study on the extent to which anchoring bypassed the weaker surface soil was performed. This study showed that proper embedment into competent soils is important as excessive strains can still develop if the anchor bond zone is insufficiently confined, potentially leading to progressive collapse.

The purpose of this paper is to describe the variability of soil rheological properties based on research carried out using load tests of ground anchors under complex geotechnical conditions. The heterogeneity of soil should always be considered when designing geotechnical constructions. In the present case, the earthwork created at the Warsaw Slope revealed an embankment of anthropogenic origin, located in a geologically and geomorphologically complex area of the Vistula valley slope. Excavation protection was anchored mainly in soils of anthropogenic origin. When the acceptance tests of the ground anchor were completed, the subsoil randomness was confirmed using nondirect, geostatistical methods. A standard solid rheological model with nonlinear fitting to the data was used. This model was established to describe the creeping activity of the ground anchor more accurately. The characteristics of man-made embankments were described using the parameters obtained with the rheological model of the subsoil.

This paper presents a case study and numerical simulations of a corner of a deep excavation in Tehran supported by soldier piles and ground anchors. This study focuses on the differences between 2D...

In urban areas, properly designed deep excavation support systems are essential for any new underground construction adjacent to the existing buildings. Diaphragm walls are widely used in India as deep excavation support system to facilitate strut-free excavation as well as to limit the soil movement of surrounding areas due to excavation. In this paper, a ten-story new commercial development required a three-level basement excavation of 12.5 m (max.) from the existing ground level (EGL). Project site consists of mixed soil condition with silty clay of varying consistency followed by dense sand underlain by a weathered rock layer. A 600 mm thick rectangular D wall panel with temporary ground anchors was used to support deep excavation wherever sufficient setback is available. In the same site, one of the corners has a restricted setback which demanded 8 m cantilever wall with high structural rigidity. Hence, T-shaped diaphragm wall panels of 600 mm thick were adopted as a permanent cantilever wall. Numerical modeling of the retention system was analyzed using WALLAP and PLAXIS 2D software. The wall deflections were monitored through inclinometers. This paper reviews the performance of cantilever diaphragm wall and rectangular panel wall with single anchor for 8 m excavation depth. Cantilever T-shaped diaphragm wall proved to be effective and stable system, where tie back is not feasible.

The article describes the technical features and advantages of using screw anchors in transport construction. Ground anchors with screw piles are assumed to be the best anchor design currently in use. It is known that screw piles not only do not violate the soil during immersion, but, as shown by numerous tests, soil compaction occurs. The design of a pile-screw anchor of increased horizontal susceptibility is presented, which allows to increase the carrying capacity of a conventional screw pile, with expansion of the functional capabilities of the screw anchor as a whole. In particular, the article discusses a method of determining the bearing capacity of a pile-screw anchor of increased horizontal stability. Method of analytical calculation of its bearing capacity on horizontal loads is given. The essence of the calculation method consists in determining the values of the bearing capacity of its structural elements: a screw pile for pulling out and a thrust plate for compressing on the ground under the influence of a horizontal load. It is assumed that this method allows theoretically determining the maximum permissible horizontal load on the pile-screw anchor. Theoretical recommendations on application of pile-screw anchor in different soil conditions are given.

The paper presents the results of the monitoring of construction for the unique residential building of 310 m high with 4-storey underground parking. One of the unique projects is the housing estate called “Abu-Dhabi Plaza” which started in 2011 in Nur-Sultan city. High-rise buildings pose new challenges for engineers, especially in the design of above-ground structures, bases, and foundations. The basement walls are formed with reinforced concrete diaphragm wall panels, which were supported with ground anchors. The shoring system analyses had been designed using PLAXIS 2D, which can assess in detail of the deformations that occur in soil. In the course of excavating a thick layer of soft, weak soil in St. Petersburg, Russia, instabilities were encountered in a 21 m long sheet pile excavation fence made of AU Arcelor 18. In light of the rather large depth (12 m) and areal extent (150 m by 80 m) of the excavation, such instabilities presented a significant challenge for the geotechnical engineers. This paper reviews the results of soil property tests performed in conjunction with the construction of the aforementioned large excavation, as well as the neighboring buildings. The need for continuous monitoring of geotechnical conditions using the methods of static sounding, to assess the zone of construction influence and to forecast the mutual influence of the structure being constructed on the surrounding buildings, is discussed. Finally, the raft foundation has recommended for future high-rise buildings to be constructed on competent residual soils.

In Taiwan, the landforms are mainly dominated by mountains and hills. Thus, countless road sections of the freeways are impossible to avoid the state-of-the-practice problems such as slope cutting. In order to stabilize the freeway slope, ground anchor technique is often employed to improve the stability of cut slope. With the increasing service time of ground anchors, their performance on the freeway slopes is highly required to be assessed. There were many disasters on freeway anchored slopes in recent years, so ground anchor inspection has also received attention to a great extent. This paper introduces the concept of safety potential analysis and then utilizes the proposed model for an anchored slope. Specifically, the proposed safety potential analysis collects plain map, historical slope inspections, monitoring data, ground anchor inspections and maintenance practices, as well as further use the geographic information system to establish the proposed model. Finally, this paper provides the predicted result from safety potential analysis and suggests the dangerous area of the studied anchored slope to the government authorities for immediately response purpose.

Paper brings a review of creep slope movement phenomena, its damage to structures, and the applied stabilization techniques in urban locations. The holistic approach to such locations based on proper ground investigation and design of preventive and remedial measures is presented on three case studies in Brno, Czech Republic. The need to respect the given geological conditions is emphasized. The related non-structural preventive measures (preventing infiltration, not undercutting the slope toe), and structural remedial measures (underpinning, anchored pile walls) application in the specific condition are described. The process of numerical analysis of strengthening pile retaining wall supporting the cut constructed in the lower part of the sliding body is presented. The importance of residual soil strength parameters for analysis of landslides is emphasized also.

With increasing level of urbanization, new buildings are erected in close proximity to existing buildings or quite close to site boundaries. Such practice affects the complexity of retaining wall installation technology. When a retaining wall is installed close to an existing building, a street or a steep slope, the stability of the wall has to be ensured first. There are cases when a retaining wall has to be strengthened by creating a permanent or temporary support, i.e. by installing ground anchors. According to literature analysis, the major problem is that a profile stops without reaching its designed depth (Van Baars). Merifield et al. distinguish three major types of anchors: circular, square and rectangular. They emphasise that anchor surface unevenness does not impact anchor resistance. According to Nagar, most frequently anchors disintegrate due to excessive tensile strength of the anchor. The increase of this force is related to tensile strength measured in anchor testing. In this paper, three types of retaining walls with ground anchors are considered: pile wall, Berlin Wall, and sheet piling with excavation depth of 6 m. The conditions are selected as follow: when walls are installed in clay soils, sandy soils, sandy soils at high groundwater levels, and when the wall is installed next to the building. Mechanical resistance and stability of construction incline are calculated by means of GEO5 software. A survey was designed basing on the calculation results and the selected evaluation criteria. In the survey geotechnical engineers rated 18 different cases. The relevance of criteria is determined by employing the entropy method after the primary results of the survey are summarised; afterwards a multiple criteria decision analysis carried out using the utility function. The multi-criteria assessment results indicate the most rational type of a retaining wall for the chosen conditions. This article is based on master thesis topic “Research on Installation Technologies of Retaining Walls with Ground Anchors”.

Cable yarding systems transport logs hoisted off the ground by a system of cables and a carriage that moves along the cable. Ground anchors are used at the end points to maintain sufficient tension between the two ends points of the cable and keep it in the air during operation. Traditional anchoring methods employ tree stumps, but as shorter stand rotations result in younger weaker stumps and because of the inability to visually inspect root structures to calculate a stump’s anchoring capacity, alternative methods of anchoring are being used more frequently. In this paper, the capacity of an alternative anchoring method, known as equipment anchoring or mobile anchoring, is assessed for guyline and skyline applications. Some critical components that are observed to influence anchor capacity are equipment weight, slope, blade embedment, angle of cable pull, and soil type. An analytical design solution for mobile anchor capacity is compared with the results of over two dozen field tests to determine the effectiveness of predicting anchor capacity. In addition to estimating the capacity of mobile anchors, a relationship between skyline and guyline loading recorded on harvest operations is analyzed.

Securing of temporary hydrotechnical structures (water-filled, panel-mounted, and other types of dikes) of different heights by means of flat earth anchors and screw piles designed to protect population centers and infrastructure against large-scale floods is considered.

A series of dynamic centrifuge model tests was conducted to investigate the effects of reinforcement on the seismic behaviour of hillside embankments consisting of sandy soils and resting on stiff base slopes. In total, three types of seismic reinforcements, namely, large-scale gabions, drainage-reinforcing piles, and ground anchors with pressure plates, were employed in the tests. The test results showed that: (1) the seismic performance of both lower and higher embankments was remarkably improved by installing large-scale gabions at the toe as they restrained the completion of the formation of sliding planes; (2) the installation of drainage-reinforcing piles at the embankment toe was rather effective in reducing the overall earthquake-induced deformation due to their high permeability and restraint effect against sliding displacement at the reinforced region; and (3) the embankments improved by ground anchors with pressure plates were not vulnerable to earthquake-induced damage due to their constraint effects even under high water table conditions. The improvement effects by the above-mentioned three types of reinforcements were presented by evaluating the global safety factors based on the results of a series of triaxial compression tests.

A ground anchor is used to withstand tensile stresses caused by loading both the natural load of the soil and external pressures, then passing the force into the ground. It is generally used to retain tensile form and lateral power structures in constructing walls, foundations, transmission towers, pile, floating docks, mooring dolphin, and offshore buildings. Various ground anchors have been widely used, such as drag, helical, circular-shaped plates, and squares. Especially for massive plate anchors, installation is complicated because it must be excavated first before installation. A challenge in engineering is especially on cohesive soil conditions (soft soil). With these considerations, it is necessary to develop innovative models that are easier to install but still have a large enough tensile capacity. This research analyzes the tensile capacity by using ground anchor folding type to overcome building problems on cohesive soil. The test was tensile capacity with four leaves and a Variation of depth-the performance of this folding type anchor based on the tensile capacity and the anchor. The results obtained in this study; the greater area of the element occurred a significant increase in tensile capacity.

This paper, consisting of full-scale pullout tests and theoretical analyses, focuses on the behavior of ground anchors under ultimate load conditions. Three ground anchors with a bonded length of 4 m were built in slightly weathered limestone and tested until their ultimate load capacities were passed. The test data indicated that two of the anchors performed well with the ultimate load capacities being nearly 3 times of the design values. The remaining anchor performed below expectation, which was diagnosed of poor grouting. Furthermore, an analytical framework was developed considering the elastoplastic stress-strain relationship at the anchor-rock interface. The developed model revealed that the bond stress was not uniform along the entire bonded length when the ultimate state was reached; instead, the bonded length was composed of plastic and elastic zones. The length of elastic zone was not significantly influenced by the increased load, while the plastic zone extended with the increase of the load. The average ultimate bond stress over the entire bonded length was a function of anchor diameters and bonded length. Thus, current recommended presumptive ultimate bond stresses should be used with caution if the anchor is very short ( 12 m).

In this research, pull-out experiments of model flip-type ground anchors (flip anchor, hereafter) were conducted in two-dimensional (plane strain) condition to investigate the fundamental pullout mechanisms of flip-type ground anchor. A transparent acrylic soil box was used as a soil box. Rectangular model flip anchors had the depth of 98 mm, and breadths, B, of 48 mm or 80 mm, so that the depths of the soil box and the model anchors were the same. The anchor was buried in the dry sand model ground and pulled-out. The experiments were carried out by changing embedment depth, h, initial positions of the anchor head (open or closed), and width of anchor head, B. Pull-out force, F, and pull-out displacement, w, were measured. The ground movements were observed using a PIV analysis. Based on the image analyses, ground failure pattern was simply modelled. The model simulated the tendency of the experimental values well. It would be expanded to three-dimension to design actual flip-type anchors.

Vorgespannte Anker werden vorrangig zur Einleitung von hohen Zugkräften verformungsarmer Konstruktionen in den Untergrund verwendet. In der Praxis zeigt sich, dass oftmals Missverständnisse zur grundsätzlichen Wirkungsweise und zum Tragverhalten herrschen, womit derartige Anker häufig nicht bestmöglich eingesetzt werden. Im gegenständlichen Beitrag wird das System Boden-Anker durch ein gekoppeltes Federmodell abgebildet und die einzelnen Phasen – das Vorspannen sowie das Aufbringen äußerer Kräfte auf das System – grafisch anhand des aus dem Stahlbau für die Berechnung von vorgespannten Schraubenverbindungen bekannten Vorspanndreiecks dargestellt. Anhand des vorgestellten Modells wird insbesondere gezeigt, welchen Einfluss das Steifigkeitsverhältnis zwischen der durch den Boden repräsentierten Feder und jener des Ankers auf die Verteilung der Kräfte im System haben. Damit können auf einfachem Weg grundlegende Aussagen zum Tragverhalten und zur Dimensionierung vorgespannter Anker getroffen werden.

In the present investigation, an attempt is made to explore the seismic response of two closely-spaced horizontal square and rectangular ground anchors embedded in non-homogenous c – soil deposit at different depths. The analysis is performed by using three dimensional finite difference program FLAC3D. Each anchor carries equal static safe working load without violating the ultimate uplift capacity under static condition. The soil is assumed to obey the Mohr–Coulomb failure criterion. The behaviour of single isolated anchor subjected to seismic loading is determined first to study the interaction effect between two nearby anchors. The horizontal acceleration response obtained from the Loma Prieta Gilroy (1989) earthquake is considered as the input horizontal excitation in the analysis. A parametric study is performed by varying the clear spacing (S) between the anchors at different embedment ratios (). The magnitude of vertical displacement of anchor plate, normal and shear stress developed at the anchor ...

The article describes the features of modeling monolithic trench “diaphragm wall” with ground anchors without the use of distribution beams on the progressive collapse caused by the failure of one of the anchors. In the simulation of the above calculation case, in the flat formulation commonly used in practice, it is assumed that the “diaphragm wall” is a continuous structure in the longitudinal direction, without taking into account the presence of vertical joints formed between the grippers when concreting the fence and the lack of connection between the longitudinal reinforcement of adjacent reinforcement spatial frameworks. The performed calculations show that the failure to take into account these circumstances leads to a significant reassessment of the ability of the “diaphragm wall” to redistribute the load from the broken anchor to the neighboring anchor and can lead to an incorrect assessment of the results of the calculation for a progressive collapse. The need to take into account the reduction of structural rigidity of the “diaphragm wall” due to the formation of cracks in two directions is also shown.

The effect described by the Euler formula for a flexible line being under tension and wrapping around a rigid support is experimentally proved to implement in the case of a nonrigid support being a ground base. Model and field experiments show essential rise in the load-bearing capacity of ground anchors with flexible tendon—E-anchors, owing to this effect. Equipment for installation of the anchors is designed and trialed. Using DEM, a 2D problem on the efficiency of the new anchors as a function of direction of pull out force applied to the tendon is solved. The E-anchors are supposed to be promising for the application in construction and operation of engineering structures.

In this paper are presented the main design criteria for the excavation and earth retaining wall solutions developed for the construction of the underground floors of a building located ta Rua do Benformoso, near to Intendente Square, in Lisbon down town, Portugal. Two different earth retaining wall solutions were developed considering local constraints, mainly geological features, topography, urban envelope and building architecture. The first solution is a Berlin-type wall braced by temporary ground anchors and steel struts. The second solution is a conventional retaining wall with reinforced concrete buttresses. This solution was performed at the garden back area due to the impossibility of using permanent ground anchors.

To improve the capacity of ground anchors, scholars and engineers worldwide have developed various types of underreamed anchors with expanded anchor parts. Underreamed anchors have a completely different mechanism from traditional shaft anchors. The expanded section of an underreamed anchor induces an end bearing force to endure the uplift force similar to a reversed pile. Therefore, the total resistance of an underreamed anchor includes friction and end bearing force. To clarify the bearing mechanism of underreamed anchors, a series of model tests were performed using fiber Bragg grating (FBG) sensors and the photogrammetry measuring method. Based on the tests, the distribution and development of the friction and end bearing force of the underreamed anchor model were acquired by the FBG sensors when being pulled out. Moreover, the deformation state of the soil around the anchor model was observed by the digital photogrammetry measuring method. Finally, the interaction mechanism between an underreamed anchor and surrounding sand was obtained, which was identified as the inherent reason for the distribution and development law of the resistance of the underreamed anchor in sand.

When we excavate an underground to build basement, the ground anchors are needed to prevent collapse of neighboring ground, subsidence and movement. Ground anchor construction required shore sheet piles, wales and struts as to maintain secure excavation. Existing box-type bracket using head part of ground anchor can not be possibly adjustable to the boring angle because the brackets are manufactured with unified angle in a factory. Also, box-type brackets have imperfection and instability caused by inequable force. In this study, a new bracket system is proposed. The bracket's side plate is reinforced and the angle of boring can be controlled. To investigate the structural performance of presented brackets, FEM analysis has been performed by using ANSYS commercial program. As a result, this bracket shows sufficient stability for all angle case and the strength is increased about 24% than existing bracket.

Underreamed ground anchor technologies have been developed to increase the capacity of ground anchors referring to reamed piles worldwide. To solve the problem of low anchor cement strength caused by muck and slag in the borehole for a traditional underreamed anchor, this paper introduces an underreamed ground anchor with a geotextile bag. Its structure and installation process are both discussed in detail. Based on the test data from 24 underreamed anchors with geotextile bags at 6 construction sites all over China, a hyperbolic model of the relationship between the load and displacement is presented to predict the capacity of a cylindrical underreamed anchor. Compared with the measured values, the predicted capacities of pointed displacements out of the tested range were sufficiently accurate for engineering practice.

This research carried out field tests on nine vertical anchors to investigate their behavior in gravel of Taichung Basin. An anchor can be categorized as a deep anchor when the free length Z exceeds 8D (D is the diameter of the anchor). The shape of the heave on the ground surface of a shallow anchor is similar to a normal distribution curve. The extended diameter of the heave was between 170 and 300 cm, which could be divided into two zones, primary and secondary, based on the failure mode of the ground. As the fixed length of a shallow anchor increased, the extended diameter also increased. The ultimate load of an anchor increased with the free length and, to a greater degree, with the fixed length of an anchor: a fixed length of only 3 m (D = 0.12 m) generated an ultimate load of over 1100 kN.

A catastrophic dip slope failure occurred suddenly at an anchored cut slope of Freeway No. 3 in 2010 after 13 years in service. Among the factors contributing to this landslide, serious corrosion on tieback anchors was the most obvious factor in addition to the groundwater hydrology inside the slope. In the past, most of the ground anchors in Taiwan were constructed with limited or no corrosion protection. So, it is likely that the tieback anchors on slopes are suffering similar corrosion problem under the humid weather condition. So, the Ministry of Transportation and Communication (MOTC) of Taiwan government launched an extensive island-wide investigation program to check the status quo of existing anchored slopes along the highways, railways, and public roads. Not surprisingly, corrosion is found to be a common problem for the existing ground anchors. A national overhaul program for the anchored slopes along the highways and railways has been launched. This paper covers the findings from the anchored slopes inspection and the measures taken to improve the corrosion protection of the existing anchors. In addition, some minor modification on anchor tendon assembly and cement grouting process has been suggested to upgrade the corrosion protection of the new anchors.

The article describes design and installation of rotary ground anchors with flexible pull bar, reports in situ and laboratory research as well as discrete element modeling results, and discusses kinematics of load bearing slab and the force interaction of the anchor and ground.

グラウンドアンカー（以下，アンカー）工法は，法面等の安定を維持する抑止工法である．アンカーは，施工後の残存引張り力の管理が重要とされており，一部のアンカーに対して残存引張り力を確認し，その結果をもとにアンカーや法面の健全性などが評価される．しかしながら，アンカーは，時間の経過とともに残存引張り力が個々でばらつきながらも法面の安定性を面的に維持する性質を持っていると考えられ，一部で確認された結果のみで健全性を評価するのは困難といった課題がある．そこで，道路法面に施工されたアンカーを対象として面的調査を実施し，背面地質やアンカーの健全性のばらつき，法面変状に伴う過緊張等の発生割合などに着目した検討を行い，アンカーの残存引張り力の分布特性に着目した新たなアンカー法面の維持管理手法の提案を行った．

Failure of several gravity retaining walls in residential areas built on reclaimed land, during the October 23, 2004 Chuetsu earthquake in Niigata Prefecture, Japan, determined the authorities to consider the seismic retrofit of the walls in order to mitigate future similar disasters in the urban environment. This study addresses the effectiveness of ground anchors in improving the seismic performance of such retaining structures through a sliding block analysis of the seismic response of an anchored gravity retaining wall supporting a dry homogeneous fill slope subject to horizontal ground shaking. Sliding failure along the base of the wall and translational failure along a planar slip surface of the active wedge within the fill material behind the wall were considered in the formulation, whereas the anchor load was taken as a line load acting on the face of the gravity retaining wall. The effects of magnitude and orientation of anchor load on the yield acceleration of the wall-backfill system and seismically induced wall displacements were examined. It was found that for the same anchor orientation, the yield acceleration increases in a quasi-linear manner with increasing the anchor load, whereas an anchor load of a given magnitude acting at various orientations produces essentially identical yield accelerations. On the other hand, the computed earthquake-induced permanent displacements of the anchored gravity retaining wall decrease exponentially with increasing magnitude of anchor load. Additionally, the influence of backfill strength properties (e.g., internal friction angle) on the seismic wall displacement appears to diminish considerably for the anchored gravity retaining wall. A dynamic displacement analysis conducted for the anchored gravity retaining wall subjected to various seismic waveforms scaled to the same peak earthquake acceleration revealed a good correlation between the calculated permanent wall displacements and the Arias intensity parameter characterizing the input accelerogram.

Kuwait City is a Middle Eastern coastal city characterized by arid conditions with shallow, saline groundwater. As some parts of the new ring road development were below the ground water level, 5,000 anchors were incorporated in the design to restrain the road against hydrostatic uplift pressures. About 750 anchors were only partially completed when they were inundated with aggressive groundwater for a period of about 2 years when dewatering was temporarily abandoned as a result of the Gulf War in 1990. Subsequently, physical, metallurgical and strength tests were undertaken to assess both the degree of corrosion and the long-term integrity of these partially completed anchors. The paper discusses the testing, the remedial measures and the long-term monitoring system. It was decided to keep some of the dewatering wells as a precautionary standby in case of future problems.

Ground anchor corrosion is a common problem for anchored slopes in Taiwan. It is partly due to the humid climate condition and abundant groundwater in the slope and partly due to poor corrosion protection of anchor design and construction. In 2010, an anchored slope at Taiwan National Freeway No. 3 failed suddenly after 13 years of service. It buried 3 cars and killed 4 people. It caught the public’s attention and initiated the island-wide program on over hauling the anchors slopes in Taiwan. Since this event, the Ministry of Transportation and Communication (MOTC) of Taiwan government had launched an extensive inspection and maintenance program for the existing anchored slopes along the freeways, highways, and railways. Totally, more than 100,000 ground anchors had been inspected. This paper will evaluate the findings from this inspection program. It includes (1) the status quo of the anchors regarding the corrosion condition and the residual load that remained on the existing anchors; (2) remedial measures taken to sustain the serviceability of existing corroding anchors; (3) measures taken to enhance the long-term durability of new anchors without changing the strand material and the practice of anchor construction commonly used by the local contractors.

To reduce the cost of landslide stabilization works, often very high, we are always looking for new effective and more economical solutions. This paper reports the case of a landslide occurred in November 2010 in the Cortiana locality (Vicenza, Italy). After a brief analysis of occurrence conditions and characteristics of the landslide, the paper presents the most important results of analyses carried out in order to design and evaluate the efficiency of some innovative interventions performed in the area, which allowed a complete slope stabilization.

Buildings with deep basements and without substantial weight of the super-structure, when constructed within highly fluctuating rise and fall of underground water level, experiences significant uplift pressure due to buoyancy effect. Use of pre-stressed rock anchor is a prominently accepted technique to fix the structure to the ground against the excessive hydrostatic pressure, when the sound rock is available at the level of basement stitched raft. The efforts are made in this study to suggest a suitable design approach and arrive at appropriate constitution of various parameters like locking of anchors to partial capacity, residual load in anchors, spacing of anchors, raft thickness and reinforcement consumption in raft, to achieve practical and economical solution which will help maintain structure in position.

In March 1989, a moderately steep slope forming sidelong ground below the B5434 Trevor to Froncysyllte Road failed after a period of exceptionally heavy rainfall and severed the highway. A long history of ground movements together with river erosion at the toe and a change in the groundwater regime within the slope created the preconditions for landslide. Site investigations characterised the ground conditions and identified the active slip surface within the compound landslide terrain. The permanent remedial measures adopted proved to be of considerable practical interest involving a bored pile anchored wall with foundations socketed into a deep sandstone foundation stratum. The anchored wall was designed to safeguard the highway and it was anticipated that deloading the slope would reduce the capacity for further movement. The wall achieved the design objective but progressive downslope movements resumed about one year after construction. They continue spasmodically to the present time with rates approaching 9 mm per year both laterally and vertically and although they affect the neighbouring areas, the highway corridor remains intact. The response of load cells attached to the ground anchors reveal two unusual patterns of increasing loads. At the eastern end of the wall, moderate load gains clearly relate to landsliding with reactivation along the existing slip surface and consequent removal of support to the wall as the ground progressively fails in a downslope direction. However, anomalous increases in loads recorded at the western end of the wall have proved more difficult to explain. They may be due either to a build up of water pressure behind the downhill portion of the wall or to localised weak ground conditions or swelling of degraded mudstones behind the wall. Monitoring of the load cells will continue in order to ensure the ongoing integrity of the highway.

In Japan, ground anchors have been widely applied for stabilization of slopes and landslides, and the technology has advanced since its introduction in Japan in the 1950s. Success in prevention of landslides during earthquakes has shown that ground anchors have demonstrated effectiveness in resisting seismic forces. However, ground anchors may degrade when they are not maintained, and the stability of slopes that are reinforced by these anchors during earthquakes may be questionable. This report shows the importance of maintenance for assurance of seismic resistance. It also reports experimental results on the seismic resistance of ground anchors. The seismic resistance of nut-fixed anchors is certified by the technical examination and certification process of Sabo Technical Center (STC pp 3–6, 2009) and others. As a result, nut-fixed ground anchors have been applied in earthquake-resistant slope measure projects, and they have been used in many recovery efforts for quays in fishing ports damaged by the 2011 off the pacific coast of Tohoku Earthquake and other earthquakes. This report presents case studies of some of these applications.