• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.788-795
• /
• 2005

In this study, the progressive failure and creep of the traditional ground anchor structure were decreased and a new ground anchor that can attain the required pull-out resistance even in soft sandy soils with low confining pressure was developed. Ground anchors are classified depending on the kind of stress the grout is subjected. If the grout material is subjected to tension then it is classified as tension anchor while when the grout material is subjected to compression it is classified as compression anchor. The ground anchor that possesses both the tension and compression mechanism mentioned above is known as composition anchor. It is the objective of this study to develope this type of composition anchor. The structure of the newly developed ground anchor was presented. Pull-out test in different types of soil and the behaviour during Pull-out test was also presented.

• Journal of the Korean Geotechnical Society
• /
• v.15 no.1
• /
• pp.63-78
• /
• 1999

For the design of compression anchor, three things should be considered. The first is a resistance force by skin friction, the second is a tension strength of tendon, and the third is a compressive strength of grout. Especially, compressive strength of grout is the most important design parameter of compression anchor. When compression anchor is pulled out from the ground, the compressive strength of grout increases by confining pressure of ground($\sigma_{tg$). Here, $\sigma_{tg$ is the confining pressure which is produced by earth pressure at rest and by lateral expansion of grout. We call this phenomenon of increase of confining pressure "poisson effect". In this paper, the design method of compression anchor called SSC anchor and the computer program for the design are developed through compression tests of anchor body grout.ody grout.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.11
• /
• pp.143-155
• /
• 2008

Ground anchors are classified depending on the kind of stress the grout is subjected to. If the grout material is subjected to tension then it is classified as tension anchor while when the grout material is subjected to compression it is classified as compression anchor. In this study a composite type anchor that possesses both the tension and compression mechanism was developed. For field tests, strain gauges were installed inside the anchor body in soft: soil. From the strain monitoring results, pull-out resistance mechanism that possesses both tension and compression strain was seen.

• Journal of Ocean Engineering and Technology
• /
• v.16 no.5
• /
• pp.49-55
• /
• 2002

The compression anchor is characterized by decrement of progressive failure, simple site work, economy and durability compared with tension anchor. In this paper, compression anchor is analysed through the laboratory element tests. The formula to be estimate the grout strength in fixed part of compression anchor and the effective reinforcement method for several types of soil were suggested. The following conclusions were made from this study : (1) A formula, which is able to calculate the grout strength in the fixed part of the compression anchor, is suggested. (2) The strength increment ratios( $R_{si}$) are 100％, 132％, 147％, 217％ according to the reinforcement method of grout. The reinforcement method is Non, Outside spiral, Inside-Outside spiral, Steel pipe, respectively. (3) The strength increment ratios( $R_{si}$) by reinforcing can be 8.23 times the strength increment effect according to the reinforcement types and ground confining pressure. (4) The steel pipe reinforcement is most effective in decomposed soil while, in the case of hard rock ground, high confining pressure is exerted on the grout, so there is no need to use reinforcements.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.16 no.1
• /
• pp.25-50
• /
• 2014

In order to identify a load transfer mechanism of ground anchors, the behavior of multi load transfer ground anchor systems was investigated and compared with those of compression type anchors and tension type anchors. Large scale model tests were performed and stress-strain relationships were obtained. The load transfer mechanism of ground anchors was also investigated in the field tests. Finally, numerical analyses to predict the load-displacement relationships of anchors were conducted. It is concluded that the load transfer characteristics of MLT anchors are mechanically much more superior in the pull-out resistance effect than those of existing compression and tension type anchors. From the results of research work, we could suggest that the max pull-out capacity of anchor capacity to each the soil condition. Also, the MLT anchors can be used to achieve both structural enhancement and economic construction in earth retaining or supporting structures.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2001.03a
• /
• pp.339-346
• /
• 2001

For temporary excavation support in private land area, the strand of ground anchor should be removed In order to get permission to install anchors. The extractable or removable-strand compression anchor system was developed and evaluated by a series of pull-out load tests. Anchor pull-out tests were performed on seven instrumented full-scale low-pressure grouted anchors installed in weathered soil at the Geotechnical Experimentation Site at Sungkyunkwan University, Four anchors are the compression type anchors and three are the tension anchors. Performance test, creep test, and long term relaxation test were performed and presented. Load distributor was developed in order to distribute large compressive stresses in grout.

• Proceedings of the KSR Conference
• /
• 2004.10a
• /
• pp.994-1000
• /
• 2004

It is growing the application of the removal ground anchor with tension force for earth retaining constructions in the downtown. Nowadays, we can find the compression dispersion anchor on many site. But, it is occur some probelems in behabior of anchors because of impossible to tense p.c strand uniformly with existing equipment due to different length of p.c strand. So we tried to tense each p.c strand uniformly with auto back equipment in-situ test. This study compared and analyzed in-situ test results of an existing equipment with those of auto back equipment by appling elastic theory. As a result of the test, It has been proved that differences of tension force in the existing equipment increases with increasing the number of p.c strands. This can cause the ultimate failure of the concentrated p.c strand and the shear failure of ground. So it has been proved that auto back equipment is necessary.

• Journal of the Korean Geotechnical Society
• /
• v.38 no.8
• /
• pp.75-84
• /
• 2022

Currently, tension ground anchors are divided into temporary and permanent based on their purpose and period of use, and their performance evaluations are presented separately. Therefore, applying the current performance evaluation's upper and lower limits to practice seems reasonable. However, because compression ground anchors have been mainly used as permanent, performance evaluation corresponding to permanent is conducted without distinction between temporary and permanent. This evaluation is a strict standard for ground anchors used as temporary, including the removal type. Because of examining the existing performance evaluation for the compression ground anchor, the lower limit can be applied without distinguishing between the temporary and permanent. However, the upper limit should be presented separately for the temporary and permanent. In applying the upper limit, it is necessary to adjust the upper limit of the anchor considering the anchored ground condition (rock or soil), the period of use, and particularly whether the load-displacement curve maintains the elastic state.

• Journal of the Korean Geotechnical Society
• /
• v.26 no.6
• /
• pp.5-19
• /
• 2010

The purpose of this study is to figure out the effect of pressurized grouting on the pullout resistance and the group effect of the compression ground anchor by performing pilot-scale chamber tests and field tests. The laboratory tests are carried out for 3-types of soils which are abundant in the Korean peninsular. Experimental results showed that the enlargement of anchor diameters estimated from the cavity expansion theory matches reasonable well with that obtained from experiments. Moreover, the required injection time as a function of the coefficient of permeability of each soil type was proposed. A series of in-situ anchor pullout tests were also performed to experimentally figure out the effect of pressurized grouting on the pullout resistance. Experimental results also showed that the effect of the pressurized grouting is more prominent in a softer ground with smaller SPT-N value in all of the following three aspects: increase in anchor diameter; pullout resistance; and surface roughness. The pressurized grouting effect in comparison with gravitational grouting was found to be almost nil if the SPT-N value is more than 50. Based on experimental results, a new equation to estimate the pullout resistance as a function of the SPT-N value was proposed. And based on in-situ group anchor pullout tests results, a new group effect equation was proposed which might be applicable to decomposed residual soils which are abundant in the Korean peninsular.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.8 no.4
• /
• pp.223-230
• /
• 2004

It is growing the application of the removal ground anchor with tension force for earth retaining constructions in the downtown. Nowadays, we can find the compression dispersion anchor on many site. But, it is occur some probelems in behabior of anchors because of impossible to tense p.c strand uniformly with existing equipment due to different length of p.c strand. So we tried to tense each p.c strand uniformly with auto back equipment in-situ test. This study compared and analyzed apply to elastic theory in-situ test results of an existing equipment with those of auto back equipment. As a result of the test, It has been proved that differences of tension force in the existing equipment increases with increasing the number of p.c strand. This can cause an ultimate failure of the concentrated p.c strand and a shear failure of ground. So it has been proved that auto back equipment is necessary.