• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.677-685
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• 2009

From the result of precise field investigation and stability examination for the cut slope, following results were acquired. 1. The cause of the cut slope collapse seems that it came from complex actions such as the weathering rock itself, existing fault zone and crack from excessive blasting. 2. As a result of analysis, it is appeared that the cut slope can be in danger of plane destruction. 3. The reinforcement force is decided by the result of limit equilibrium analysis. 4. For reinforcement the method after relaxing the slope was judged as the most proper method to the cut slope as comparing/analyzing Rock Anchor, Rock Bolt and method after relaxing the slope.

• Geomechanics and Engineering
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• v.21 no.6
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• pp.565-570
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• 2020

Large tonnage pile foundation load test system is designed in this paper by using pre-stressed technique to optimize the design of anchor pile reaction beam system, in which project pile can be successfully taken as anchor pile. The test results show that the cracks and excessive deformations of the prestressed anti-force device designed in this study have not occurred, and the prestressed tendons of the anchor pile ensure that the anchor pile will not be pulled and fractured, and the prestressed tendons can be reused, thus ensuring the safety and reliability of the test. This test method can directly test bearing capacity of long rock-socketed piles, and analysis bearing behaviors from test results of sensors which embedded in the pile. Through test studied, authors summarized the vertical bearing characteristics of long rock-socketed piles and the main problems that should be paid attention to during design and construction, and provided reliable solutions.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.1147-1153
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• 2009

The failure modes of rock anchors subjected to tension can be defined as follows: tensile failure of tendon, shear failure on tendon-grout interface, shear failure on grout-rock interface and tensile failure of rock. This study proposes a design method to induce the rock anchor systems to avoid the brittle failure by ensuring the minimum embedded length of rock anchors. Pull-out test results of full-scale rock anchors show that the proposed method is effective in predicting the design conditions expecting the ductile tendon failure.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1022-1028
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• 2008

From the result of precise field investigation and stability examination for the rock slope, following results were acquired. 1. The weathering rock itself, existing fault zone and underground water complexly effect cut slope so that plane destruction may appear by fault zone. 2. The reinforcement force was decided by the result of limit equilibrium. 3. For rock cut slope, the Rock Bolt was judged as the most proper method to the cut slope as comparing/analyzing Rock Anchor, Rock Bolt and method after relaxing the slope.

• Journal of the Korean Geotechnical Society
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• v.22 no.12
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• pp.45-55
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• 2006

This paper presents the results of full-scale uplift load tests performed on 30 passive anchors grouted to various lengths at Taean site in Korea. Various rock types were tested, ranging from highly weathered to sound gneiss. Rock anchors were installed over a wide range of rock types and qualities with a fixed anchored depth of $1{\sim}4m$. The majority of installations used SD4O-D51 no high grade steel rebar to induce rock failure prior to rod failure. In many tests, rock failure was reached and the ultimate loads were recorded along with observations of the shape and extent of the failure surface. The test results, the failure mechanisms as well as uplift capacities of rock anchors depend mostly on rock type and quality, embedded fixed length, and the strength of rebar. Based on test results, the main parameters governing the uplift capacity of the rock anchor system were determined.

• Tunnel and Underground Space
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• v.16 no.2 s.61
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• pp.146-155
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• 2006

The target slope of this study, formed during the construction of highway, is the very high infinite slope where sliding began along the discontinuity. Although an attempt was made to stabilize the upper part of the slope by installing the rock anchors, large scale failure was occurred at the lower part if the reinforced area. Afterwards, subsequent failures were observed two times. To investigate the cause of the failure, residual shear strength was measured by performing the direct shear test of rock specimen of the site. The anchor design was based on the pull-out test. Considering the slope surface where the undulation was severe and the variation of strength was very large, buttressing was used to obtain the required anchoring capacity.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.635-650
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• 2018

Many people have been recognized that the Korean Peninsula is no longer safe area from the earthquake by the recent earthquakes occurred in the country. The earthquakes that occurred at Pohang and Gyeongju appeared differently from them considered in the seismic design and researches on the seismic design method have been also conducted by many researchers. Studies on seismic loads are mainly focused on existing superstructures, and research involving them has been actively carried out in reality. However, paper regarding structural stability of reinforcement from seismic load such as soil-nails, rock-bolts, ground anchors which were constructed to ensure stability of serviced structure have been published rarely. In this study, ground anchor been effected by static load and seismic load which is settled in the weathered rock is analyzed. Results for static load are obtained from field test and seismic load is from numerical analysis. In this study, the behavioral characteristics of the ground anchor were analyzed by numerical analysis in case of seismic loading based on the result of the in-situ tensile test of the ground anchor settled weathered rock. As a result, settlement of concrete block due to application of tension force for ground anchor occurred as well as following loss of axial force for ground anchor. Also, as bond length and period of seismic load are longer, increasement of displacement is greater.

• Geomechanics and Engineering
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• v.35 no.4
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• pp.395-409
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• 2023

Long-span suspension bridges have tunnel anchor systems to maintain stable cables. More investigations are required to determine how closely tunnel excavation beneath the tunnel anchor impacts the stability of the tunnel anchor. In order to investigate the impact of the adjacent tunnel's excavation on the stability of the tunnel anchor, a large-span suspension bridge tunnel anchor is utilised as an example in a three-dimensional numerical simulation approach. In order to explore the deformation control mechanism, orthogonal tests are employed to pinpoint the major impacting elements. The construction of an advanced pipe shed, strengthening the primary support. Moreover, according to the findings the grouting reinforcement of the surrounding rock, have a significant control effect on the settlement of the tunnel vault and plug body. However, reducing the lag distance of the secondary lining does not have such big influence. The greatest way to control tunnel vault settling is to use the grout reinforcement, which increases the bearing capacity and strength of the surrounding rock. This greatly minimizes the size of the tunnel excavation disturbance area. Advanced pipe shed can not only increase the surrounding rock's bearing capacity at the pipe shed, but can also prevent the tunnel vault from connecting with the disturbance area at the bottom of the anchorage tunnel, reduce the range of shear failure area outside the anchorage tunnel, and have the best impact on the plug body's settlement control.

• Journal of the Korean Geotechnical Society
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• v.24 no.10
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• pp.147-160
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• 2008

This paper presents the results of full-scale loading tests performed on 54 passive anchors and 4 group anchored footings grouted to various lengths at several sites in Korea. The test results, the failure mechanisms as well as uplift capacities of rock anchors depend mostly on rock type and quality, embedded fixed length, properties of the discontinuities, and the strength of rebar. Anchors in poor quality rocks generally fail along the grout/rock interfaces when their depths are very shallow (a fixed length of less than 1 m). However, even in such poor rocks, we can induce a more favorable mode of rock pull-up failure by increasing the fixed length of the anchors. On the other hand, anchors in good quality rocks show rock pull-up failures with high uplift resistance even when they are embedded at a shallow depth. Laboratory test results revealed that a form of progressive failure usually occurs starting near the upper surface of the grout, and then progresses downward. The ultimate tendon-grout bond strength was measured from $18{\sim}25%$ of unconfined compressive strength of grout. One of the important findings from these tests is that the measured strains along the corrosion protection sheath were so small that practically the reduction of bond strength by the presence of sheath would be negligible. Based on test results, the main parameters governing the uplift capacity of the rock anchor system were determined. By evaluation of the ultimate uplift capacity of anchor foundations in a wide range of in situ rock masses, rock classification suitable for a transmission tower foundation was developed. Finally, a very simple and economical design procedure is proposed for rock anchor foundations subjected to uplift tensile loads.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.265-272
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• 2001

Excavation in a big city is different from excavation in a local area because construction methods and stability are directly connected in a loss of life. Especially, estimate of rock mass slope stability is excuted by more detail and safty work. In this study, we are made reserches in rock mass slope stability and safety method that the slope is closed by elementary school in a big city. The result of many field study and numerical analysis is shown up direct reinforcement used to anchor.