• Journal of the Korean Geotechnical Society
• /
• v.17 no.6
• /
• pp.69-83
• /
• 2001

In order to make use of finished municipal landfill as a construction site, it is necessary to consider environmental and geotechnical aspects for the ground improvement and application of waste landfill. In environmental aspect, methods for management of landfill gas and leachate have to be established, and in geotechnical aspect, it is necessary to investigate available method for constructing structure foundation. In this study, the finished landfill was selected for pilot test. Investigation about the environmental characteristics of the waste landfill was performed to establish the methods far management of landfill gas according to monitoring the gas quantity and to investigate economical efficiency according to utilizing landfill gas. Investigation about cases of utilizing the waste landfill in Korea and abroad as construction site was performed and pilot tests were performed to analyze the improvement effects of methods such as dynamic compaction method and PG pile method available to waste landfill. The results of this study showed that economical profits could be gained by utilizing landfill gas and improved waste landfill, besides, dynamic compaction method was effective in case of improvement depth being shallow, and PG pile method was effective in case of improvement depth being deep.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.509-512
• /
• 2008

The lining concrete of water tunnel is a much capability to occur crack due to drying shrinkage and vibrator compaction etc. Because of crack of concrete induce structural problem and decrease durability of concrete, it is need to reduce crack of concrete. In this an Analytical study to analyze the effect of curing of concrete and compaction on the lining concrete. As the results, it was found that control of construction condition into curing of concrete and compaction improve on construction efficiency of the lining concrete.

• Journal of the Korean GEO-environmental Society
• /
• v.10 no.5
• /
• pp.11-18
• /
• 2009

When underground pipe is installed, backfill materials need proper compaction. But in case of circular underground pipe, compaction of backfill material is difficult and compaction efficiency is poor at beloe the pipe. It caused the stability of underground pipe is reduced and various damages occurred. One of the solutions to solve this problem for underground pipe is to use controlled low strength material (CLSM). CLSM is made by concept of low strength concrete, which is applied to geotechnical engineering field. The representative characteristics of CLSM are self-leveling, self-compacting and flowability. In addition, its strength can be controlled and its construction method is simple. The behavior of underground pipe was investigated by finite element analysis for various backfill materials under same condition. As a result, in case of using the CLSM as backfill material, surface settlement and displacement of pipe are reduced comparing with those in case of using field soil or sand.

• Journal of the Society of Disaster Information
• /
• v.14 no.3
• /
• pp.305-314
• /
• 2018

Purpose: Dynamic Replacement Method currently lacks of sufficient research, implementation cases, and case histories, compared with other comparable methods, such as Dynamic Compaction Method. Method: In this study, for Dynamic Replacement Method, the effective improvement depth and improved strength were analyzed for silty clayey soils. Results: Testbed test was performed to verify the effectiveness of Dynamic Replacement Method followed by the main dynamic replacement implementation on real construction site. Conclusion: A The effects of changes of soft ground depth, dynamic replacements' diameter, depth, spacing, and applied energy on dynamic replacement efficiency in silty clays were assessed and the followings were found: Empirical coefficient for soil $n_R$ of Dynamic Replacement Method was within the range of 0.14~0.32 and its ${\sqrt{WH}}$ is recommended to be 1.25~2.5 times of those from Dynamic Compaction Method.

• Journal of the Korean Geosynthetics Society
• /
• v.19 no.4
• /
• pp.11-20
• /
• 2020

This study introduced the compact grouting method that can be used for improving soft ground and restoring buildings with unequal subsidence. The pump used in the traditional compact grouting method is a system that injects one hole each, which reduces the construction efficiency, and the analog injection method manually manages the construction by field workers, making it difficult to manage consistent quality. Pump and quality control system were developed to solve problems in existing construction. Since field supervisor determines amount of injected materials by using analog equipment and controls manually, it is difficult to manage consistent quality of construction. Therefore, the quality control system was developed in order to solve that problem. The quality control system consists of automatic mixing system of injection materials, multiple simultaneous injection pumps, and injection management monitoring system. Performance of the quality control system was verified through on-site testing, and ground improvement performance was verified through quality testing after testing and testing of the compact grouting method. Therefore, it is expected that the integrated quality control system developed will improve the quality assurance and efficiency and stability of construction at sites where construction and quality verification are difficult.

• Journal of the Korean Society of Safety
• /
• v.32 no.4
• /
• pp.34-39
• /
• 2017

Typical flow regime of overflow at barrier or weir constructed in mid and small streams becomes as the submerged flow during most flood events. One of major causes of barrier failure has been reported as the levee-scour near the conjuction node between barrier and levee. However, most related design guidelines in Korea have not mentioned about the protection of levee around barrier or weir in detail. Furthermore, most previous researches have focused on the flow characteristics of overflow around several types of weirs but they did not have considered the material properties of levee itself. In this study, local scour near barrier was investigated with different material properties of levee under the submerged overflow condition which is assumed to reenact a flood event. Based on results from Fritz et al. and Mavis et al., a theoretical formula was also proposed in initial stage of laboratory experiments. And hydraulic experiments were carried out for the verification of the proposed formula. Levee was installed in the prismetic trapezoidal open channel and most parts were made of concrete except for movable section in which scour was expected to occur for the efficiency of experimental procedure. Each compaction of movable section in levee was followed by the basis of the KS F 2312. Further, after performing the experiments to find the optimum water content for each sediment, the specific amount of water was injected before flowing water. The difference between the proposed theoretical formula and experiment results was not much but considerable, which might be caused by the effect of compaction. For theoretical approach, it seemed that the formula did not take into account the compaction of levee, thus the correction coefficient for levee compaction determined in the literature was considered. Finally, the formula for the length of scour around barrier or weir was proposed, which can be useful to predict a levee in the reference design of revetment in mid and small streams. As shortly future study, scour length of levee around barrier or weir under different flow conditions such as perfect overflow condition will be studied and it will be able to contribute to suggest the design formula or criteria under all overflow conditions near barrier or weir.

• Journal of Environmental Science International
• /
• v.15 no.5
• /
• pp.431-438
• /
• 2006

The strength, water permeability, and photo-degradation efficiency of NOx of porous concrete with a new concept were studied in this paper. The porous concrete was comprised of coarse aggregate of maximum size 40 mm, cement, silica fume, water and air-entraining(AE) water reducing agent. The strength of porous concrete was strongly related to its matrix proportion and compaction energy. An experimental test was carried out to study the parameters of cement proportions and silica fume content for pavement applications of porous concrete which were paving a footpath, a bikeway, a parking lot, and a driveway. The regressed equations of relation-ships between compressive strength and flexural strength, and coefficient permeability and void ratios were indicated as y=7.69x+71.74 and $y=0.42e^{0.28x}$. A method of making an air purification-functioning road, which was spraying a mixture of a photocatalyst, cement, and water onto the surface of the road, was suggested.

• International Journal of Highway Engineering
• /
• v.5 no.2 s.16
• /
• pp.25-35
• /
• 2003

During construction of circular lifeline pipe, the non-proper compaction along the pipe and the decrease of compaction efficiency are the main problems to induce the failure of underground pipe. The use of CLSM(controlled low strength materials) is one of the applications to overcome those problems. In this research, the numerical analysis by PENTAGON FEM program was carried out for 20 cases with the couple of combinations on bedding materials, backfill materials, and pipes. From the FEM analysis, the use of CLSM as backfill materials reduced the settlement of ground surface and the deformation of pipe employed. In case of the vertical deformation on the pipe, common soil backfill for flexible pipes showed 2 times for rigid pipes, but CLSM backfill case did less deformation than the soil backfill for rigid pipes. CLSM backfills for rigid pipes showed the similar results. Judging from the FEM analysis, the use of CLSM increases the structure capacity of the underground pipes.

• Journal of the Korean GEO-environmental Society
• /
• v.12 no.9
• /
• pp.27-33
• /
• 2011

In the case of the existing method of underground pipe construction, the difficulty of the bedding compaction of pipe causes reducing the compaction efficiency and the stability of the underground facilities and conclusively damaging the structures. One of the methods to solve these problem is using the flowable fills as a backfill material. Therefore, in this study, numerical analysis of the underground pipe was performed in order to evaluate the behavior of pipe according to backfill mixtures. To estimate the deformation characteristic of the underground pipe, the displacement of the main part of the pipe, ground settlement and vertical earth pressures were measured in different backfill mixtures and maintaining the other conditions constantly. As a result of numerical analysis, using the flowable fills as the backfill material is better than using sand in reducing the ground settlement, the pipe deformation and the vertical earth pressure aspect.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.16 no.11
• /
• pp.1103-1116
• /
• 1991

The characteristics of transform coefficients of discrete Gabor transform and the performances of their progressive coding are investiganted. The adaptive transform coding SAC is used for the progressive transmission. Exprerimental results show that although DGT has relatively low energy compaction property and coding efficiency, it yields good quality with greaty reduced block artifact and good edge at each stage of the progressive transmission.