• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.5
• /
• pp.2425-2433
• /
• 2011

DSM (Deep Soil Mixing) is to establish soil-cement column by injecting of cement slurry and blending it in soft ground and have been introduced to Singapore in 1980s and now a days quite popular and considered as alternative method to the jet grouting for temporary earth retaining works and foundations. Herein this paper, the results of lab mixing test based on comparison of characteristics between OPC (Original Portland Cement) and PBFC (Portland Blast Furnace Slag Cement), DSM field trial test and main installation results including monitoring, was presented and it would be referred to similar site later.

• Journal of Industrial Technology
• /
• v.24 no.A
• /
• pp.239-250
• /
• 2004

Numerical analysis were performed to investigate the stability and internal movement of tunnel located beneath the base of abutment of bridge according to the method of supporting tunnel. Two supporting methods of the multi-staged grouting method with steel pipes and the large diameter of pipe supporting method were used in the centrifuge model tests. The slip form of model lining, specially built to simulate the process of tunnel excavating under the condition of accelerated g-level, was used in the centrifuge model tests. Four centrifuge model tests were performed, changing the supporting methods of the multi-staged grouting method with steel pipes and the large diameter of pipe supporting method and the location of model abutment base of bridge. For internal displacement of tunnel, movements of the crown. The left and the right sides of spring line were measured during the proceeds of excavating tunnel in centrifuge model tests. Test results were compared with numerically estimated values of internal displacement of tunnel by using the commercially available FEM software of PENTAGON-3D. It was found that they were in good agreements and the large diameter of pipe supporting method was more stable than the multi-staged grouting method with steel pipes with respect to the internal movement of tunnel.

• Journal of the Korean Geotechnical Society
• /
• v.22 no.12
• /
• pp.25-31
• /
• 2006

This paper studies the field applicability of the Special Chemical grouting Method (SCM) in reinforcing and reducing permeability of the back of an existing continuous wall. SCM uses double rod which imposes intermediate pressure ($981{\sim}9,810kPa$) to disturb, cut, discharge, and mix the ground. It is observed that a bulb is formed by using cement paste and environmentally friendly injection materials with minimal alkali leaching. Uniaxial compression tests, test for chemical properties and fish poison test are performed. Test results indicate that the method results in higher durability, less leaching through the use of the environmentally friendly injection material and faster mobilization of the strength. In addition, field tests confirm the formation of the bulb and the seepage cutoff wall.

• Journal of the Korean GEO-environmental Society
• /
• v.18 no.7
• /
• pp.13-20
• /
• 2017

Soil nailing is ground reinforcement method using the shear strength of ground and the pullout shear resistance force of nail. It is mainly used for reinforcement of cut slopes, earth retaining structures and retaining walls, etc. It may be designed considering the pullout resistance of nail in the case of earth retaining structure and retaining wall, but it should be designed considering not only pullout resistance but also shear and bending resistance in the case of slope. However, conservative designs considering only pullout resistance are being done and most of the studies are about increasing pullout resistance by improving of material, shape and construction method of nail. Actually, Shear bending deformations occur centering on the active surface in ground reinforced with the nail. The grout with relatively low strength is destroyed and separated from the reinforcing material. As a result, the ground is collapsed while reducing the frictional resistance rapidly. Therefore, it is necessary to develop the method to increase the shear resistance while preventing separation of nail and grout body. In this study, an experimental study was conducted on new soil nailing method which can increase shear resistance by forming protrusions through pressurized grouting after installing a packer on the outside of deformed bar.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.6
• /
• pp.61-72
• /
• 2002

In this study, model tests were performed to evaluate the injection characteristics of cement grouting which was used as waterproof method for leakage of underground structures. To simulate in situ condition, model tests were performed with varying the ground conditions such as the kinds of test soils, soil density, water content, etc. and the injection conditions such as kinds of injection materials, injection pressure, injection quantity, injection velocity, etc. From the results of model tests, the major factors influencing the permeability of injection material were determined to be the kinds of soils and soil density. To obtain optimal injection effects, injection should be performed after investigating the condition of backside ground accurately.

• International Journal of Highway Engineering
• /
• v.10 no.2
• /
• pp.193-203
• /
• 2008

This study was conducted to investigate the feasibility of the expedite construction of new pavement systems using precast concrete slabs and to develop the design and construction guide based on the results of the experimental construction. Half scale concrete slabs were designed and fabricated and the optimal reinforcement design, linkages between the slabs in the longitudinal and transverse directions, and the grouting methods were investigated. The experimental construction was performed fast and easily by assembling two slabs in the longitudinal direction and the other two in the transverse direction. The slabs were leveled and the pockets and the space between the slab bottom and the underlying layer were grouted. From the experimental construction, details about the design and construction of the precast pavements were acquired. Finally, the design and construction guide for the newly constructed precast concrete pavement systems was developed.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.21 no.2
• /
• pp.301-321
• /
• 2019

The development of a rapidly hardening seal material applicable to steel pipe multistage grouting is described in this paper. In the multistage technique, seal materials are inserted to prevent the backflow of main grouting material. The grouting material must be inserted only after sufficient time has passed for the seal material to reach a gel state. Otherwise, the fluid seal material mixes with the main grouting material and a backflow of the grouting material occurs, thereby making its in situ insertion difficult. Furthermore, if the seal material remains in the gel state for too long a time, it solidifies; and the main grouting material will not be able to seep into the soil. The gel time, i.e., the time needed for the fluid seal material to turn into a gel state, determines the construction period of steel pipe multistage grouting. The gel time is one of the important factors in this technique, because it impacts the total tunnel construction period significantly. This study develops a rapidly hardening calcium aluminate material, which can reduce the gel time and shorten the construction period while retaining proper sealing function. It also presents a method to determine whether the seal material has reached the gel state as well as the quality standard and bleeding rate testing method for the seal material in the gel state.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.21 no.4
• /
• pp.455-478
• /
• 2019

In this paper, we conducted experimental investigation on the field applicability through the verification of reinforcement effect of the steel pipe reinforcement grouting using high strength steel pipe. SGT275 (formerly known as STK400) steel pipe is generally applied to the traditional steel pipe reinforcement grouting method. However, the analysis of tunnel collapse cases applying the steel pipe reinforcement grouting shows that there are cases where the excessive bending and breakage of steel pipe occur. One of the reasons causing these collapses is the lack of steel pipe stiffness responding to the loosening load of tunnels caused by excavation. The strength of steel pipe has increased due to the recent development of high strength steel pipe (SGT550). However, since research on the reinforcement method considering strength increase is insufficient, there is a need for research on this. Therefore, in this study, we conducted experiments on the tensile and bending strength based on various conditions between high strength steel pipe, and carried out basic research on effective field application depending on the strength difference of steel pipe through the conventional design method. In particular, we verified the reinforcement effect of high strength steel pipe through the measurement results of deformed shape and stress of steel pipe arising from excavation after constructing high strength steel pipe and general steel pipe at actual sites. The research results show that high strength steel pipe has excellent bending strength and the reinforcement effect of reinforced grouting. Further, it is expected that high strength steel pipe will have an arching effect thanks to strength increase.

• Journal of the Korean Geotechnical Society
• /
• v.21 no.1
• /
• pp.43-50
• /
• 2005

Jet grouting method is widely being used in many geotechnical problems, especially for the purpose of reinforcement of clayey ground and cut-off wall of sandy ground. However, its design depends on highly empirical method, in which many researches have been undertaken. This study investigated the effect of cavitation on jet grouting. Small-scaled model tests were carried out using specially designed and fabricated device to analyze the effect of cavitation on jet grouting with various test conditions including ground condition, injection pressure, and injection time. The test results show that cavitation has a significant effect on jet grouting, and it has a potential for engineering application.

• Journal of the Korean GEO-environmental Society
• /
• v.13 no.10
• /
• pp.77-83
• /
• 2012

Recently, excavations using propped walls were popularized in downtown due to reduced settlement of nearby structures. These excavations is induced strain to propped walls or settlement in near ground. In this study, the ground reinforcing effect was proven using NDS, which is an inorganic injection material. Injection tests were performed to compute optimum injection pressure and volume. Next, calibration chamber tests were performed by using computed injection pressure and volume, and wall behaviour was examined for overburden pressures of 50kPa and 150kPa. Ground reinforcing effect was shown when the material behind the propped wall was grouted. From test results, optimum injection pressure was 350kPa and the optimum volume was 10L considering economics. Calibration chamber test results show that after the material was grouted, the maximum settlement was reduced to 19% of the non-grouted condition. For overburden pressures of 50kPa and 150kPa behind the wall, the settlement of the wall increased by 58% and 57% when compared to the case of no overburden pressure.