• Title, Summary, Keyword: Grouting

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Jet-grouting in ground improvement and rotary grouting pile installation: Theoretical analysis

  • Wang, You;Li, Lin;Li, Jingpei;Sun, De'an
    • Geomechanics and Engineering
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    • v.21 no.3
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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.

Experimental study on the performance of compensation grouting in structured soil

  • Zheng, Gang;Zhang, Xiaoshuang;Diao, Yu;Lei, Huayang
    • Geomechanics and Engineering
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    • v.10 no.3
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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.

An improved approach to evaluate the compaction compensation grouting efficiency in sandy soils

  • Xu, Xiang-Hua;Xiang, Zhou-Chen;Zou, Jin-Feng;Wang, Feng
    • Geomechanics and Engineering
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    • v.20 no.4
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    • pp.313-322
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    • 2020
  • This study focuses on a prediction approach of compaction compensation grouting efficiency in sandy soil. Based on Darcy's law, assuming that the grouting volume is equal to the volume of the compressed soil, a two-dimensional calculation model of the compaction compensation grouting efficiency was improved to three-dimensional, which established a dynamic relationship between the radius of the grout body and the grouting time. The effectiveness of this approach was verified by finite element analysis. The calculation results show that the grouting efficiency decreases with time and tends to be stable. Meanwhile, it also indicates that the decrease of grouting efficiency mainly occurs in the process of grouting and will continue to decline in a short time after the completion of grouting. The prediction three-dimensional model proposed in this paper effectively complements the dynamic relationship between grouting compaction radius and grouting time, which can more accurately evaluate the grouting efficiency. It is practically significant to ensure construction safety, control grouting process, and reduce the settlement induced by tunnel excavation.

An experimental study on the improving reliability of grouting by using p-q-t chart analyzing technique (P-q-t chart 분석기법을 이용한 그라무팅 신뢰성 향상 방안에 관한 실험적 연구)

  • Chon, Byung-Sik;Choi, Dong-Chan;Kim, Jin-Chun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.10 no.4
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    • pp.383-395
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    • 2008
  • The grouting is one of the improved techniques which is aim to decrease the permeability and to strengthen the soft ground. But The grouting method has many problems about a suitability of grouting procedure and an effectiveness of grouting after grouting work because of a technical characteristic operated inside the soil. The grouting $p{\sim}q{\sim}t$ chart of a typical index about grouting rate and time alteration of grouting pressure is one method to estimate the suitability of grouting factor with monitoring during grouting procedure. This study is automatic grouting system (AGS) which can control the testing and grouting procedures. It can make the detailed $p{\sim}q{\sim}t$ chart and analyze the grouting characters of the ground by comparing the detailed pattern of $p{\sim}q{\sim}t$ chart with standard pattern. If using the $p{\sim}q{\sim}t$ chart derived from AGS in the grouting work, it is an objective standard estimating the suitability of grouting factor with grouting materials, grouting method, grouting rate and grouting pressure, as results it expects successfully to improve reliability of the grouting work.

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Change of groundwater inflow by cutoff grouting thickness and permeability coefficient

  • Kim, Youngsang;Moon, Joon-Shik
    • Geomechanics and Engineering
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    • v.21 no.2
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    • pp.165-170
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    • 2020
  • The groundwater during tunnel excavation not only affects the stability of the tunnel and constructability but also causes the subsidence of the upper ground due to the lowering of groundwater. Generally, the cutoff grouting is applied as a countermeasure to reduce the groundwater inflow during tunnel excavation, and the cutoff grouting is often applied in the range of plastic zone around the tunnel. However, grouting in the plastic zone is only appropriate for ground reinforcement purposes, and guidelines for the application range of cutoff grouting and the targeted permeability coefficient of the grouting zone are required. In this study, the relationship between groundwater inflow into tunnel and application range of cutoff grouting and permeability coefficient is proposed and compared with numerical analysis results. It was found that grouting with tunnel radius thickness is appropriate to reduce the groundwater inflows effectively. More than 90% reduction in groundwater inflow can be achieved when the annular area of the tunnel radius thickness is grouted with a permeability reduction ratio of 1/50~1/200.

An improved model of compaction grouting considering three-dimensional shearing failure and its engineering application

  • Li, Liang;Xiang, Zhou-Chen;Zou, Jin-Feng;Wang, Feng
    • Geomechanics and Engineering
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    • v.19 no.3
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    • pp.217-227
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    • 2019
  • This study focuses on an improved prediction model to determine the limiting grouting pressure of compaction grouting considering the ground surface upheaval, which is caused by the three-dimensional conical shearing failure. The 2D-dimensional failure curve in Zou and Xia (2016) was improved to a three-dimensional conical shearing failure for compaction grouting through coordinate rotation. The process of compaction grouting was considered as the cavity expansion in infinite Mohr-Coulomb (M-C) soil mass. The prediction model of limiting grouting pressure of compaction grouting was proposed with limit equilibrium principle, which was validated by comparing the results in El-Kelesh et al. (2001) and numerical method. Furthermore, using the proposed prediction model, the vertical and horizontal grouting tube techniques were adopted to deal with the subgrade settlement in Shao-huai highway at Hunan Provence of China. The engineering applicability and effectiveness of the proposed model were verified by the field test. The research on the prediction model for the limiting grouting pressure of compaction grouting provides practical example to the rapid treatment technology of subgrade settlement.

Field Experiments on the Cutoff Grouting Around Waterway Tunnel (도수터널의 차수 그라우팅 현장시험)

  • 김덕근;김교원
    • The Journal of Engineering Geology
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    • v.11 no.1
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    • pp.81-99
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    • 2001
  • In order to clarify an effect of the cutoff grouting, a series of field experiments were performed during construction of the waterway tunnel from the River Gilancheon(Andong) to the Youngcheon dam. The experiments were conducted in three different ways based on the grouting time in the construction sequence, i.e., the pre-grouting, after-grouting and consolidation grouting tests. And those were also planned to compare the efficiency of grouting in relation to the material types of grout, base rock types and other geologic factors such as discontinuities, depth and direction of grouting holes, and number of grouting stages. Among the materials of grout employed in the experiments, such as a common Portland cement, a micro-cement, a micro-cement with sodium silicate, and a urethane, the urethane was the most effective as the cutoff grouting. And for the same grout material, the pre-grouting was more effective to cutoff the water inflow comparing to the after-grouting and the consolidation grouting. For the rock types, the grouting efficiency in the sedimentary rocks as a base rock was less than the other rocks such as granite and volcanic rocks, which is believed due to the smaller separation of joints and the abundance of infilling materials in the joints developed in the sedimentary rocks. There was no direct relationship between the total RMR value of the rock mass and the grouting efficiency, however, the joint separation which is one of the RMR criteria is believed to have positive relation to the grouting efficiency. And the direction of the grouting holes might not so much affect on the grouting efficiency while increasing the number of grouting stage showed the better results.

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Pullout Characteristics of Reinforcing Body Using Pressure Re-injection Grouting Method (압력재주입 그라우팅 방식을 이용한 보강재의 인발특성)

  • Lee, Bongjik;Kim, Sangsu;Youn, Junsik;Lee, Jongkyu
    • Journal of the Korean GEO-environmental Society
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    • v.11 no.10
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    • pp.25-31
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    • 2010
  • Anchor, soil nail, micropile have been widely used for slope reinforcement and foundation. These all methods need grouting work after placing reinforcing member. In domestic case, gravity fill techniques and pressure grouting techniques are mainly used. In contrast the pressure re-injection grouting method is not commonly used because grouting equipment and lack of practical application example is short and the verification of reinforcing effect is difficult. Pressure re-injection grouting is a kind of post grouting which technique increases the radial stresses acting on the grout body and causes irregular surface to be developed around bond length that tends to interlock the grout and the ground. In this study, the field test was performed to evaluate the reinforcing effect with the variation of grouting methods and pullout characteristics of reinforcing member placed by pressure re-injection grouting method. The test results showed that the post-grouting methods were useful to increase the pullout capacity.

Application of Grouting for Liquefaction Resistance Using Automatic Grouting System (그라우팅자동관리시스템을 이용한 액상화 방지 그라우팅의 적용)

  • Kong, Jinyoung;Kang, JunO;Cho, Hyunsoo;Kim, Jinchun;Chun, Byungsik
    • Journal of the Korean GEO-environmental Society
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    • v.12 no.9
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    • pp.79-87
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    • 2011
  • This study conducted the research on the method of grouting quality management and the improvement effect by applying grouting construction's quality management technology to automatic injection management equipment through measure of liquefaction based on the case of reinforcement applying grouting at the region where liquefaction happened at section 12 site of highway construction. The pressure(p), speed(q), grouting penetration radius(R) value from injection pressure, injection speed, characteristics of grain size, and characteristics of viscosity through p-q-t chart analysis was applied to the automatic grouting system which could improve the quality management of grouting. Standard penetration test results after injection showed that N values represented 5-20 and the prevention of liquefaction became possible.

Evaluation of Composite Ground Improvement at Structural Foundation Ground by Super Injection Grouing (SIG공법에 의한 구조물기초지반에서의 복합지반개량 평가)

  • 김종국;손형호;이호관;성기광
    • Proceedings of the Korean Geotechical Society Conference
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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.

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