• Geotechnical Engineering
• /
• v.4 no.4
• /
• pp.5-18
• /
• 1988

A series of CU triaxial compression tests were conducted to investigate the variation of -untrained shear strength of underconsolidated clay at different degrees of consolidation. The soil samples were artificially made by one-dimensional consolidation using soft Bangkok Clay. The test results showed that the undrained shear strength of clay parabolically increased convoking downward with increasing degrees of consolidation. However, all the measured shear strength were unanimously related to the effective stress. These experimental results were used in the numerical analysis. A finite element computer program was developed to investigate the stability of submarine .slope undergoing rapid deposition taking into account the variation in soil compressibility and permeability during the consolidation process. The relationships of degree of consolidation with time as a function of rate of deposition and angle of slope were established. A method of predicting the time of slope failure and the volume of moving mass of soil was also made.

• Geomechanics and Engineering
• /
• v.31 no.4
• /
• pp.375-384
• /
• 2022

The variation of the undrained shear strength (c_u) is an important consideration for assessing slope stability in engineering practice. Previous studies focused on the three-dimensional (3D) stability of slopes in normally consolidated clays generally assume the undrained shear strength increases linearly with depth but does not vary in the horizontal direction. To assess the 3D stability of slopes with spatially varying undrained shear strength, the kinematic approach of limit analysis was adopted to obtain the upper bound solution to the stability number based on a modified failure mechanism. Three types failure mechanism: the toe failure, face failure and below-toe failure were considered. A serious of charts was then presented to illustrate the effect of key parameters on the slope stability and failure geometry. It was found that the stability and failure geometry of slopes are significantly influenced by the gradient of c_u in the depth direction. The influence of c_u profile inclination on the slope stability was found to be pronounced when the increasing gradient of c_u in the depth direction is large. Slopes with larger width-to-height ratio B/H are more sensitive to the variation of c_u profile inclination.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.35 no.3
• /
• pp.47-62
• /
• 1993

The laboratorv model test was carried out to investigate the behavior of pore water pressure, the critical amount of rainfall for slope failure, the pattern of failure, and the variation of seepage line at the slope with the uniform material of embankment by changing the slope angles and rainfall intensities. The results were was summarised as follows : 1.At the beginning stage of rainfall, the negative pore pressure appeared at the surface of slope and the positive pore pressure at the deep parts. But, the negative one turned into the positive one as the rainfall continued and this rapidly increased about 50 to 100 minutes before the slope failure. 2.The heavier the rainfall intensity, the shorter the time, and the milder the slope, the longer the time took to reach the failure of slope. 3.As the angle of the slope became milder, the critical amount of rainfall for slope failure became greater. 4.Maximum pore water pressure was 10 to 40g/cm$^2$ at the toe of slope and 50 to 90g/cm$^2$at the deep parts. 5.In the respect of the pattern of slope failure, surface failure of slope occurred locally at the toe of slope at the A-soil and failure of slope by surface flow occurred gradually at the top part of slope at the B-soil. 6.As the rainfall continued and the saturation zone in the embankment was formed, the seepage line went rapidly up and also the time to reach the total collapse of slope took longer at the B-soil. 7.As the position of the seepage line went up and the strength parameter accordingly down, the safety factor was 2.108 at the A-soil and 2.150 at the B-soil when the slope occured toe failure. Minimum safety factor was rapidly down to 0.831 at the A-soil and to 0.936 at the B-soil when the slope collapsed totally at the top part of slope.

• Journal of the Korean Society of Industry Convergence
• /
• v.8 no.3
• /
• pp.161-168
• /
• 2005

This study is analysis for adjacent structures and ground movement by deep excavation work. Underground Inclinometer has shown that deformation of increment is minor within to allowable limit. According to the measurements result of slope and crack for adjacent structures, a detached house showed bigger than hospital structure to deformation of increment. Variation of underground water level didn't effect so much to ground and adjacent structures movement because underground water flows in rock and didn't give the water press to propped walls. Measurement data of strut variation is within tolerance limit. Because excavation site's wall was strengthened suitably. This study will contribute in establishment of measurement standard and information-oriented construction during deep excavation in multi-layered ground including rock masses.

• Proceedings of the KIEE Conference
• /
• 2005.07b
• /
• pp.1279-1281
• /
• 2005

Generally a single-phase SRM(switched reluctance motor) has several stator and rotor poles but these are excited by one regulated current at the same time. It has only one inductance variation. It means that the positive torque is only generated in the positive slope of the inductance variation. The single-phase SRM can not be started by itself. The single-phase SRM can be started by itself if the rotor is placed in the positive slope of the inductance variation. Then, the starting device is required to place the rotor in the starting position before start. On this paper, the equation of the force requisite for the starting device is derived using by the frictional force of the rotor

• Ocean Systems Engineering
• /
• v.12 no.4
• /
• pp.385-402
• /
• 2022

This paper deals with the study of hydrodynamic pressure in reservoir adjacent to the concrete gravity dam subjected to dynamic excitation. Widely famous finite element method is used to discretize the reservoir domain for modelling purpose. Pressure is considered as nodal variable following Eulerian approach. A suitable nonreflecting boundary condition is applied at truncated face of reservoir to make the infinite reservoir to finite one for saving the computational cost. Thorough studies have been done on generation of hydrodynamic pressure in reservoir with variation of different geometrical properties. Velocity profile and hydrodynamic pressure are observed due to harmonic excitation for variation of inclination angle of dam reservoir interface. Effect of bottom slope angle and inclined length of reservoir bottom on hydrodynamic pressure coefficient of reservoir are also observed. There is significant increase in hydrodynamic pressure and distinct changes in velocity profile of reservoir are noticeable for change in inclination angle of dam reservoir interface. Change of bottom slope and inclined length of reservoir bottom are also governing factor for variation of hydrodynamic pressure in reservoir subjected to dynamic excitation.

• The Journal of the Korea Contents Association
• /
• v.9 no.4
• /
• pp.347-354
• /
• 2009

The stone pagodas include small internal spaces such as holes of Buddha's bones generally and the space's positions and sizes can make an influence on the maintenance of the stone pagoda. Also, inclined angles of the stone pagodas are an important factor to be considered to preserve them. In this paper, the Junghyesaji thirteen-storied stone pagoda subjected to its weight was analyzed through the finite element method to investigate the weakest location of the pagoda and study how size variation of internal spaces and slope variation influenced the weakest location. And criterions were proposed to examine the safety of the stone pagoda along the size variation of the internal spaces and the slope variation in view of the deflections and the stresses to examine fractures of the pagoda.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.4 no.1
• /
• pp.11-19
• /
• 2008

Groundwater flow in confined aquifer and heat transport in underground geologic media are using same governing equation(line source) like well fuction. Therefore the conventional slope method using only later data obtained from in-situ thermal response test to determine the thermal conductivity of vertical geothermal heat exchanger(GHEX) is basically identical with one of Theis straight line method of aquifer test under artesian condition. In case that the pumping rate(Q, $m^3$/d) and drawdown(s,m) which are used for input data of existing hydrogeologic computer programs for aquifer test are replaced and converted to supplying heat energy per unit length of bore hole(Q/L,w/m or Kcal/h.m) and temperatures (T,$^{\circ}C$)measured at in and out-let of GHEX as in put data respectively, thermal conductivity around geothermal heat exchanger can be easily estimated without any special modification of the existing hydrogeologic computer program. Two numbers of time series temperature variation data obtained from in situ geothermal response test are analized using Theismethods(standard curve and straight line method) by using existing aquifer test program and conventional Slope method proposed by ASHRAE. The results show that thermal conductivity values estimated by two straight methods are identical and the difference of estimated values between standard curve methods and Slope method are also within acceptable ranges. In general,the thermal conductivity estimated from Theis straight linemethod gives more accurate value than the one of Slope method due to that Slope method uses only visual matching otherwise Theis method uses automatic curve matching estimation with reducing RSS.

• Atmosphere
• /
• v.26 no.3
• /
• pp.401-412
• /
• 2016

A 3D sonic anemometer has been installed at Yongpyong alpine slope since Oct. 23th 2014 to observe the slope winds and to analyze turbulent characteristics with the change in surface cover (grass and snow) and the synoptic wind strength. Eddy covariance method has been applied to calculate the turbulent quantity after coordinate transformation of a planar-fit rotation. We have carefully selected 3 good episodes in the winter season (23 October 2014 to 28 February 2015) for each category (9 days in total), such as grass and snow covers in case of weak synoptic wind condition, and grass cover of strong synoptic wind. The diurnal variations of the slope winds were well developed like the upslope wind in the daytime and downslope wind in the nighttime for both surface covers (grass and snow) in the weak synoptic forcing, when accordingly both heat and momentum fluxes significantly increased in the daytime and decreased in the nighttime. Meanwhile, diurnal variation of heat flux was not present on the snow cover probably in associated with significant fraction of sunlight reflection due to high albedo especially during the daytime in comparison to those on the grass cover. In the strong synoptic regime, the most dominant feature at Yongpyong, only the southeasterly downslope winds were steadily generated irrespective of day and night with significant increases in momentum flux and turbulent kinetic energy as well, which could suggest that local circulations are suppressed by the synoptic scale forcing. In spite of only one season analysis applied to the limited domain, this kind of an observation-based study will provide the basis for understanding of the local wind circulation in the complex mountain domain such as Gangwon in Korea.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.3
• /
• pp.1027-1035
• /
• 2013

In this study, two rainfall patterns are utilized for practical consideration of rainfall phenomena in unsaturated soil slope design. One is the I.D.F (Intensity-Duration-Frequency) method which is an existing design rainfall method and ignores the effect of the variation of the rainfall according to the time. The other is the Huff method which considers this effect oppositely. First, the safety of factor of the slope according to the variation of an initial suction which means the precedent rainfall effect was examined by means of the application of the I.D.F method. Through the application of two rainfall patterns, it was discussed how the rainfall pattern affects the factor of safety of the slope. As a result, it is found that the Huff method is more practical on the evaluation of the slope stability than the I.D.F method.