• 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.

• Journal of the Korean GEO-environmental Society
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• v.8 no.6
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• pp.5-12
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• 2007

Mudstone has characteristics that it has high enough strength and stiffness in a dry condition, but the strength and stiffness decrease in a wet condition with groundwater infiltration. The sliding of cut slope frequently encountered in Pohang area has been reported due to the rapid reduction of shear strength in mudstone after being exposed to the air. The study in this paper shows that mudstone having enough strength in a boring stage has lost the strength after installing PRD (percussion rotary drill) steel pipe pile inducing an insufficient bearing capacity. Field test has been performed to investigate the most favorable method for increasing a pile bearing capacity in mudstone with various methods such as MSG (Micro Silica Grouting) around the tip and side of a pile, the perimeter grouting combined with Micro pile reinforcement, and concrete filling after tip reinforcing grouting. MSG has been turned out to be the most favorable method for increasing a pile bearing capacity in mudstone, confirmed by the static load test.

• The Journal of the Korea Contents Association
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• v.20 no.11
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• pp.669-675
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• 2020

This research has focused on comparing the capacity predicted by the theoretical formula with the one measured by field load tests to examine characteristics of the bearing capacity of a helical pile. The helical pile is featured by a central shaft with one or more helical-shaped bearing plates. Being established by a small rotary attached to an excavator that applies toque, the helical piles can be readily constructed at narrow sites, especially in an urban area with relatively less noise than the others requiring driving and excavation. Although many cases of the helical pile constructions can be recently found, the bearing capacity of the pile has been limitedly studied. To this end, this contribution analyzes and presents comprehensive results of the ten field loading tests with an application of different parameters depending on joint condition and specification of the helical piles, and types of tests and grouting.