• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
• /
• pp.1240-1249
• /
• 2008

Jacket anchor was developed to increase the pullout resistance of general ground anchor in soft ground, and the mechanism of pullout resistance of jacket anchor was analyzed. Also, the ultimate bond stress of jacket anchor was estimated by ultimate resistance which is determined by field tests. Grout milk was injected into the jacket to make grout bulb of jacket anchor. The formation of grout bulb of jacket anchor increases the diameter of grout bulb, ground strength and confining pressure between anchor grout and soil. From the twelve field test results, it was observed that the pullout resistance of jacket anchor is 15.38~295.02%(average 83.53%) greater than that of general ground anchor, and plastic deformation of jacket anchor is 20.78~1,496.45%(average 288.78%) smaller than that of general ground anchor at the same load cycle. Especially, it was investigated that the increase of ultimate resistance over 200% and the reduction of plastic deformation over 600% was obtained in gravel layer. It means that the jacket anchor is superior to the general ground anchor in gravel layer. Finally, the ultimate bond stress was proposed to design jacket anchor.

• 한국해양공학회지
• /
• 제16권2호
• /
• pp.44-52
• /
• 2002

The mechanism of pullout resistance of compression anchor is analysed. This anchor is developed through the field pullout tests and the laboratory element test. The compression anchor is characterized by decrease of progressive failure, simple site work, economy and durability compared with tension anchor. The characteristics of compression anchor, compared with tension anchor. mainly are summarized as follows ; (1) The plastic displacement of anchor body is very small during pullout of anchor. (2) Total anchor length decreases by the shortening of free length; (3) The progressive failure is decreased.; (4) The safety factor for pullout resistance increases with time after construction of anchor.

• 한국해양공학회지
• /
• 제17권4호
• /
• pp.43-51
• /
• 2003

The resistance mechanism of anchor changes according to the types of anchor. Friction anchors are classified into tension and compression types. In this study, the characteristics and mechanism of pullout are analysed, and the design method of anchor and computer program for design are developed through compression test results of anchor body grout. The characteristics of compression anchor, compared with tension anchor, are summarized mainly as follows: (1) The effect of progressive failure of compression anchor body are much smaller than those of tension anchor during pullout of anchor: (2) The skin friction resistance is increased by Possion effect of grout (anchor body) during pullout of compression anchor.

• 한국농공학회지
• /
• 제32권4호
• /
• pp.71-80
• /
• 1990

Model tests for the ultimate pullout resistance of anchorages and investigation of failure behaviors in cohesionless soil have been conducted. The factors affecting the anchorage are mostly the geometry of the system, and soil properties of sands. The main conclusions of the experimental work were as follows. 1. The load - displacement relationship can be a form of parabolic curve for all plates. 2. The change in ultimate pullout resistance of anchor is mostly affected by embedment ratio and size of anchor, and influenced to a lesser degree by its shape. 3. Critical embedment ratio which is defined as the failure mode changes from shallow to deep mode is increased with increasing height of anchor. 4. For a constant anchor height, as the width of anchor increases the ultimate pullout resistance also increases. However, considering the efficiency of anchor for unit area, width of anchor does not appear to have any sigrnificant contribution on increasing anchor city. 5. Anchor capacity has a linear relation to sand density for any given section and the rate of change increases as the section increases. Critical depth determining the failure patterns of anchor is decreased with a decrease of sand density. 6. With increasing inclination angle, size of anchor, and decreasing embedment ratio, the ultimate pullout resistance of anchor under inclined loading is significantly decreased. 7. The ultimate pullout resistance of double anchor, a method of improving single of anchor capacity, is influenced by the center - to - center spacing adjacent anchors. It is also found that tandem and parallel anchor rigging arrangements decrease the anchor system capacity to less than twice the single anchor capacity due to anchor interference.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 추계 학술발표회
• /
• pp.1060-1064
• /
• 2010

Ground anchors are mostly used to improve the resistance capacity of retaining walls. The end of the anchor is connected to retaining wall through tendons and the forces in tendons are transferred to ground. In this study, we plan that the new anchor system increases the tension force in tendons and improves the pullout resistance characteristics of the system. In order to increase the pullout resistance capacity of existing anchor system, the new anchor system is made by attaching four steel sticks to the tip of anchor end. So the field test results showed that the pullout resistance capacity of the wedge-shaped ground anchor was acceptable to elastic displacement range.

• Geomechanics and Engineering
• /
• 제12권4호
• /
• pp.675-688
• /
• 2017

The anchor block is a specially designed concrete member intended to withstand pullout or thrust forces from backfill material of an internally stabilized anchored earth retaining wall by passive resistance of soil in front of the block. This study presents small-scale laboratory experimental works to investigate the pullout capacity of a concrete anchor block embedded in air dry sand and located at different distances from yielding boundary wall. The experimental setup consists of a large tank made of fiberglass sheets and steel framing system. A series of tests was carried out in the tank to investigate the load-displacement behavior of anchor block. Experimental results are then compared with the theoretical approaches suggested by different researchers and codes. The appropriate placement of an anchor block and the passive resistance coefficient, which is multiplied by the passive resistance in front of the anchor block to obtain the pullout capacity of the anchor, were also studied.

• 한국철도학회논문집
• /
• 제20권4호
• /
• pp.500-511
• /
• 2017

최근 경주지진이 일어나게 되면서 지진의 진동에 의한 구조물의 안정성에 대한 관심이 증가하고 있다. 하지만 국내 앵커분야의 경우 설계하중에 대한 안정성만 고려하고 있을 뿐 진동에 대한 안정성에 대한 연구는 미미한 실정이다. 마찰형 앵커의 경우 시공 중 발생하는 발파진동 등으로 인하여 앵커의 저항능력을 상실한 경우가 종종 보고되고 있다. 이에 반하여 지압형 앵커의 경우 구조적으로 마찰형 앵커에 비하여 진동저항능력이 우수할 것으로 판단되나 이러한 특성에 대한 연구는 거의 진행되지 않았다. 본 연구에서는 새롭게 개발한 지압형 앵커의 발파진동과 지진에 대한 안정성을 검증하기 위하여 현장시험을 수행하였으며 수치해석을 통하여 내진안정성을 검증하였다. 그 결과 현장시험의 경우에는 마찰형 앵커보다 발파진동에 대한 저항성능이 우수하였으며, 수치해석을 이용한 내진해석의 경우 또한 마찰형 앵커에 비하여 저항성능이 우수한 것으로 분석되었다.

• 한국지반공학회지:지반
• /
• 제14권6호
• /
• pp.139-151
• /
• 1998

SI 앵커는 지반개량 앵커를 의미한다. 이는 앵커를 지지하는 지반을 JSP로 개량한 것으로, SI 앵커체는 80cm 정도의 직경을 가지게 된다. SI 앵커는 앵커체와 지반사이의 마찰저항력과 앵커체 앞면의 지압저항력으로 인해 높은 인발저항력을 발휘하게 되는데, 특히 마찰저항력은 JSP로 개량된 앵커체의 직경의 증대로 인해 상당히 증가하게 된다. 본 연구에서는 SI 앵커의 인발저항기구를 분석하기 위해 실내 모형실험과 현장실험을 실시하였다. 공기건조 모래지반 내에서의 실내 모형실험을 통해 SI 앵커 주변지반의 변형률장을 분석하였는데, 이는 토조 벽면에 설치된 라텍스 멤브레인을 이용한 사진 분석법을 통해 이루어 졌다. 10매의 변형률게이지가 부착된 특수 설계된 PVC 파이프를 앵커체 내에 설치하고 변형률을 측정하여 현장실험의 결과를 분석하였는데, 역시 실내 모형실험과 같이 앵커체 내에서의 변형률을 측정하였다.

• Steel and Composite Structures
• /
• 제21권2호
• /
• pp.357-371
• /
• 2016

Column base connections are critical components in steel structures because they transfer axial forces, shear forces and moments to the foundation. Exposed column bases are quite commonly used in low- to medium-rise buildings. To investigate shear transfer in exposed column base plates, four large scale specimens were subjected to a combination of axial load (compression or tension) and lateral shear deformations. The main parameters examined experimentally include the number of anchor rod, arrangement of anchor rod, type of lateral loading, and axial force ratio. It is observed that the shear resisting mechanism of exposed column base changed as the axial force changed. When the axial force is in compression, the resisting mechanism is rotation type, and the shear force will be resisted by friction force between base plate and mortar layer. The specimens could sustain inelastic deformation with minimal strength deterioration up to column rotation angle of 3%. The moment resistance and energy dissipation will be increased as the number of anchor rods increased. Moreover, moment resistance could be further increased if the anchor rods were arranged in details. When the axial force is in tension, the resisting mechanism is slip type, and the shear force will be resisted by the anchor rods. And the shear resistance was reduced significantly when the axial force was changed from compression to tension. The test results indicated that the current design approach could estimate the moment resistance within reasonable acceptance, but overestimate the shear resistance of exposed column base.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 춘계 학술발표회
• /
• pp.1286-1293
• /
• 2010

The ground anchor used in domestic area, which resists by adhesion between anchor body and the ground to the external force, seems not to be adequate for soft ground and urban area where the boundary between structures is close because the ground is disturbed and lost its strength during boring. In order to overcome such a shortcoming an expanded anchor system has been developed. The ground expansion is accomplished by means of Pulse Discharge Technology. In this technology, a high voltage of electricity is stored and discharged in milliseconds which induces high pressure acting on the ground. By making a couple of bulbs, a passive resistance as well as shaft resistance are mobilized, and therefore a higher pullout resistance comparing existing ground anchors is developed.In this study, a couple of full scale tests were conducted in order to figure out how much the resistance of an expanded anchor increases comparing to the straight. As a result, it was found that a remarkable increase in ultimate pullout capacity is observed for the soft ground and as the number of bulb increases. In addtion, as a result of applying to a cut slope reinforcement, it appeared that the length of fixed zone of anchor can be reduced effectively.