• Geomechanics and Engineering
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• 제21권3호
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• pp.279-288
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• 2020

The permeation grouting is a commonly used technique to improve the engineering geology condition of the soft ground. It is of great significance to predict the permeation range of the grout so as to ensure the effects of grouting. This paper conducts a theoretical analysis of jet-grouting effects in ground improvement and rotary grouting pile installation by utilizing deformation-permeation coupled poroelastic solutions based on Biot's theory and Laplace-Fourier integral transform technique. The exponential function and the intermittent trigonometric function are chosen to represent time-dependent grouting pressure usually encountered in ground improvement and rotary grouting pile installation process, respectively. The results, including the radial displacement, the hoop stress, the excess pore fluid pressure, the radial discharge, and the permeation radius of grout, are presented for different grouting time, radial positions and grouting lengths. Parametric study is conducted to explore the effects of variation of the exponent in the exponential grouting pressure-time relationship on grouting-induced responses. It is expected that the proposed solutions can be used to estimate the permeation range of grouting in ground improvement and rotary grouting pile installation.

• Geomechanics and Engineering
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• 제12권1호
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• pp.35-52
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• 2017

In order to evaluate the grouting effects of water-rich fault in tunnels systematically, a feasible and scientific method is introduced based on the extension theory. First, eight main influencing factors are chosen as evaluation indexes by analyzing the changes of permeability, mechanical properties and deformation of surrounding rocks. The model of evaluating grouting effects based on the extension theory is established following this. According to four quality grades of grouting effects, normalization of evaluation indexes is carried out, aiming to meet the requirement of extension theory on data format. The index weight is allocated by adopting the entropy method. Finally, the model is applied to the grouting effects evaluation in water-rich fault F4-4 of Qingdao Jiaozhou Bay Subsea Tunnel, China. The evaluation results are in good agreement with the test results on the site, which shows that the evaluation model is feasible in this field, providing a powerful tool for systematically evaluating the grouting effects of water-rich fault in tunnels.

• 한국지반환경공학회 논문집
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• 제3권4호
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• pp.37-49
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• 2002

본 연구에서는 고강도 고내구성 및 환경에 대한 안정성이 높은 주입재료를 주입재 형태별로 즉 현탁액형, 용액형 주입재에 배합설계를 실시하여 주입압, 지반조건에 따른 주입효과와 환경적 유해성을 분석 검토하고자 한다. 주입재 특성 및 주입효과에 대한 연구결과, 현탁액형 주입재에서는 초미립자시멘트가 보통시멘트에 비하여 상당히 높은 침투성 및 고결율을 나타냄을 알 수 있었고 용액형 주입재에 사용된 인산과 탄산수소나트륨의 경우 초미립자시멘트와 유사한 경향을 나타내었다. 주입된 고결체의 압축강도 시험결과, 현탁액형 주입재의 초미립자시멘트가 상당한 고강도를 나타났으나 용액형 주입재의 경우 현탁액형 주입재에 비하여 매우 낮은 강도를 나타내었다. 또한 주입재가 가지고 있는 환경적 유해성 여부를 평가하기 위해 대상시료를 주입재의 원재료 및 주입재의 고결시편의 양생일수에 따라 중금속 용출시험을 실시한 결과, 선정한 약액조합 및 고결체의 중금속 함량은 규제기준을 만족하였다.

• Geomechanics and Engineering
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• 제10권3호
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• pp.335-355
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• 2016

Most laboratory test research has focused on grouting efficiency in homogeneous reconstituted soft clay. However, the natural sedimentary soils generally behave differently from reconstituted soils due to the effect of soil structure. A series of laboratory grouting tests were conducted to research the effect of soil structure on the performance of compensation grouting. The effects of grouting volume, overlying load and grouting location on the performance of compensation grouting under different soil structures were also studied. Reconstituted soil was altered with added cement to simulate artificial structured soil. The results showed that the final grouting efficiency was positive and significantly increased with the increase of stress ratio within a certain range when grouting in normally consolidated structured clay. However, in the same low yield stress situation, the artificial structured soil had a lower final grouting efficiency than the overconsolidated reconstituted soil. The larger of normalized grouting volume could increase the final grouting efficiency for both reconstituted and artificial structured soils. Whereas, the effect of the overlying load on final grouting efficiencies was unfavourable, and was independent of the stress ratio. As for the layered soil specimens, grouting in the artificial structured soil layer was the most efficient. In addition, the peak grouting pressure was affected by the stress ratio and the overlying load, and it could be predicted with an empirical equation when the overlying load was less than the yield stress. The end time of primary consolidation and the proportion of secondary consolidation settlement varied with the different soil structures, grouting volumes, overlying loads and grouting locations.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.347-354
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• 2002

In this paper, when structures are constructed in the soft ground with poor bearing capacity at Incheon International Airport(railroad area), as for the grouting columns built In soft ground by high pressure jet grouting with Triple tube rod(super injection grouting), the effects on reinforcement and bearing capacity of ground are investigated. A unconfined compressive strength tests has been performed on the specimens sampled from the grouting columns and a mass plate bearing test has been performed on a grouting column. The test results show that super injection grouting has a sufficient effect on composite ground improved of foundation ground and reatraint of settlement of structure.

• 지질공학
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• 제12권2호
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• pp.189-202
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• 2002

본 연구에서는 파쇄대구간에서 현장시험을 실시하여 암반의 역학특성과 투수성 등을 평가함으로써 그라우팅에 의한 암반파쇄대의 개량효과를 평가하였다. 시험위치 주변 암반에 실시된 압밀그라우팅으로 인한 평균적인 암반개량정도는 변형계수가 평균 2.30, 탄성계수가 2.49로 나타나 탄성계수에 대한 개량이 더 효과적으로 나타났다. 본 연구를 통하여 얻어진 결과는 다음과 같다. (1) 주입단계가 진전됨에 따라 총 주입량의 변화는 암반의 일체화를 보여준다. (2) 압밀그라우팅의 실시 후에 측정된 루전치의 감소는 투수성의 개량을 보여준다. (3) 그라우팅 주입은 암반의 변형성과 강도특성의 개량을 가져을 수 있다. (4) 암반 개량전에 변형성이 큰 암반은 더욱 큰 역학특성의 개량을 보인다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.398-403
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• 2002

The low slump mortar grouting is widely used in reinforcement of structural foundation and ground improvement in soft ground. It also has merit that construction is possible in insufficient space. In this study, the main purpose is to evaluate effects for contiguous structures that can be happened along with soft ground improvement by the low slump mortar grouting. To estimate these effects, numerical analysis using finite difference method was applied. It was performed to analyze settlement, upheaval and horizontal displacement of surrounding ground and to measure horizontal stress variation by the first and the second grouting in the pile foundation.

• 한국지반환경공학회 논문집
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• 제11권12호
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• pp.37-45
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• 2010

초미립자시멘트는 입자 크기가 마이크로화되어 실트성 지반까지 주입가능하지만 점성이 높아 침투성이 저하되는 단점이 있다. 본 연구에서는 유동화제를 사용하여 점성을 낮춘 초미립자주입재의 그라우팅 효과를 평가하고자 암반에서 초미립자주입재와 보통시멘트주입재의 주입효과를 비교하였다. 시추조사, 현장수압시험, 공내재하시험, 공내전단시험, 단위주입량분석, p~q~t chart 유형 분석을 실시하였다. 시험 결과 초미립자주입재를 사용하는 경우가 보통시멘트 주입재를 사용하는 경우보다 투수성, 탄성계수 및 변형계수, 단위주입량 및 주입재 회수율 등 측면에서는 유리하지만 전단응력 측면에서는 차이가 거의 없는 것으로 나타났다.

• 한국지반환경공학회 논문집
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• 제20권8호
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• pp.13-20
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• 2019

지반보강을 위해 국내에서 널리 사용되고 있는 공법으로 약액주입공법, 앵커공법, 소일네일공법 및 마이크로파일공법 등을 들 수 있다. 이러한 지반보강공법은 보강재의 종류, 설치방법, 프리스트레스의 유무 및 그라우팅 방법에 따라 다양한 공법으로 개발되고 있으나, 공통적으로 지반보강재의 강성, 그라우트와 보강재의 마찰력 및 그라우트와 지반의 마찰력이 주요 설계변수이다. 따라서, 최적화된 지반보강재는 보강재 자체의 인장강도가 큰 재료로써 보강재와 그라우트사이의 마찰력이 크며, 그라우트와 지반사이의 마찰력을 향상시킬 수 있는 최적의 그라우팅 방법의 적용이 필요하다. 이에, 본 연구에서는 보강재의 형상과 그라우팅 방법에 따른 보강효과를 평가하고자 총 20여개의 실내모형실험을 실시하였으며, 실험결과 타공+날개보강형과 포스트그라우팅 방법이 보강 효과가 가장 우수한 것으로 나타났다.

• Geomechanics and Engineering
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• 제21권4호
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• pp.357-369
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• 2020

Different from the conventional planar fracture and simplified Newton model, for power-law slurries with a lower water-cement ratio commonly used in grouting engineering, flow model in geological rough fractures is built based on ten standard profiles from Barton (1977) in this study. The numerical algorithm is validated by experimental results. The flow mechanism, grout superiority, and water plugging of pseudo plastic slurry are revealed. The representations of hydraulic grouting properties for JRCs are obtained. The results show that effective plugging is based on the mechanical mechanisms of the fluctuant structural surface and higher viscosity at the middle of the fissure. The formulas of grouting parameters are always variable with the roughness and shear movement, which play a key role in grouting. The roughness can only be neglected after reaching a threshold. Grouting pressure increases with increasing roughness and has variable responses for different apertures within standard profiles. The whole process can be divided into three stationary zones and three transition zones, and there is a mutation region (10 < JRCs < 14) in smaller geological fractures. The fitting equations of different JRCs are obtained of power-law models satisfying the condition of -2 < coefficient < 0. The effects of small apertures and moderate to larger roughness (JRCs > 10.8) on the permeability of surfaces cannot be underestimated. The determination of grouting parameters depends on the slurry groutability in terms of its weakest link with discontinuous streamlines. For grouting water plugging, the water-cement ratio, grouting pressure and grouting additives should be determined by combining the flow conditions and the apparent widths of the main fracture and rough surface. This study provides a calculation method of grouting parameters for variable cement-based slurries. And the findings can help for better understanding of fluid flow and diffusion in geological fractures.