응력 Parameter에 관한 고찰

김방식 충주대 산업과학기술연구소 1994 産業科學論文集 Vol.2 No.-

The Streugth meant parameters of Soil have reserched in order to determine the failure Criterion and analyses for geotechnical Construction such as footings and retaining Walls. I studyed of some parameters in here as followers. 1. parameter of effective principle stress. P'=(σ1'+ σ2'+ σ3')/3=(σa'+2σr')/3 2. parameter of deviator stress in triaxial Condition ◁수식 삽입▷ (원문을 참조하세요) 3. parameter of plane Strain Condition. s'=(σ1'+σ3')/2, t=(σ1'+σ3')/2

모래의 액상화 거동에 미치는 인자

김방식 忠州大學校 2002 한국교통대학교 논문집 Vol.37 No.2

The factors affecting liquefaction susceptibility of saturated sands are in many occations and must be investigated to understand of it. From the comprehensive experimental results on reconstituted specimens, the behaviour of undrained and saturated sand is considerably affected by the fabric at the identical initial void ratio-effective stress state. Water pluviation specimen simulated in-situ behaviour very closely and very loose moist tamped specimen in different to in-situ sands. The sensitiveness to liquefaction is affected from static and cyclic depends on the initial state variation and effective stress path under undrained shear. The others are ability of the testing device, loading method and data aquisition system to measure the true behaviour of sands. Foundamental factors that influence liquefaction sensitiveness of saturated sands are considered in this study.

응력파를 이용한 타압말뚝의 지지력 연구

金芳植 충주대학교 산업과학기술연구소 2002 産業科學論文集 Vol.10 No.-

Stress wave measuring on piles has become possible after the advent of modern electronic testing and recording equipment. It has been more and more common in a number of countries to use stress wave measurement during pile driving for evalution of the bearing copacity and the integrity of the pile. I studied of the basic concept of the stress wave on driving pile and compared the result of dynamic loading test to prove the relationship between the allowable bearing copacity of the theory based on the soil foundation. The result of compared is as follow. 1. The point bearing capacity was from 110% to 200% grester than the result of dynamic loading test and frictional resistance of dynamic loading test was 210% greater than the actual value of the theory. 2. The allowable bearing capacity of dynamic loading test was from 110% to 120% greater than the value of the theory. 3. Comparing the result of the test and the theory in case of the allowable bearing capacity, the result of the dynamic loading test was close to the value of the theory.

반복하중하에서 조립질 흙의 액상화

김방식 충주대학교 2006 한국교통대학교 논문집 Vol.41 No.-

The effect of the gravel contents on the liquefaction behavior under the isotropical consolidated coarse grained soil as gravel-sand mixtured specimens are performed at the same relative density(Dr=40%) and void ratio(e=0.7) with various gravel contents in this research. The results of test of coarse grained soil showed that pore water pressure development and axial strain behavior during undrained cyclic loading represent the similar behavior to the loose sand mainly due to high void ratio for the isotropically consolidated specimen at the 40% of relative density with low gravel contents(0%, 20%, 40%), but, for the specimens with high gravel content(70%), both behaviors tend to be similar to the dense sand. At the same void ratio(e=0.7) with higher gravel contents show the same behaviors of pore water pressure development and axial strain as the loose sand behaviors due to lower relative density under the isotropically consolidated specimen, but, for the lower gravel content, these behaviors show the representative behavior of the dense sand. And the strength of liquefaction increases with decreasing the gravel content. Thus, it is confirmed that the liquefaction strength of the gravel-sand as coarse grained soils depends both on relative and void ratio of the whole mixture rather than the relative density of the sand matrix.

타입말뚝의 지반내 흙과의 상호작용에 대하여

金芳植 충주대학교 1997 한국교통대학교 논문집 Vol.32 No.2

The michanics of the pile/soil system were studied using the field data obtained from pre-cast concrete piles which were driven at the site of the construction of a ferry pier in this paper.It may be expected that the soil will experience both compressive and shear stress and strains in two principal directions. I conclude that correlation of the pile/soil system were studied as follows 1. Shape of curve between the CAPWAP and the hypothetical one is very similar. 2. And both of its curves are very sensitive to the changes in Φand N. 3. Pile load carrying capacity in granular soil does not increase very much after an L/r ratio of 40 reached.

단일하중하의 실트질 모래의 이방압밀 파괴 거동에 관한 연구

金芳植 충주대학교 산업과학기술연구소 2002 産業科學論文集 Vol.10 No.-

A consolidated-undrained triaxial compression tests were carried out to study the flow failure behavior of a saturated loose silty sand in the state of anisotropic consolidation with four different consolidation pressure ratios under the monotonic loading. The specimens were formed at the relative density of about 17% by the wet tamping method. For the test, it were resulted that the steady state line is a unique straight line on p'-q space for all K_c and the slope of the collapse line decreased linearly with increasing the value of K_c. The relationship between the residual strength(Sus) and the peak strength(Sp) of the loose silty sand is found to be represented as a general equation, Sp/Pc'= A_L+B_L (Sns/Pc') irrespective of the value of K_c. These A_L and B_L, tend to vary linearly with increasing the value of K_c.

자갈-모래 혼합토의 액상화 거동

김방식,강병희,윤여원 한국지반공학회 2007 한국지반공학회논문집 Vol.23 No.10

In this research, the effects of the gravel content on the liquefaction behavior for both of the isotropically and -anisotropically consolidated gravel-sand mixtures are investigated. For this purpose, the cyclic triaxial tests for the specimens with the same relative density (Dr=40%) and variations of gravel content were performed. On the other hand, a series of undrained cyclic triaxial tests were carried out on the isotropically consolidated gravel-sand mixtures with the same void ratio (e=0.7) and from 0% to 30% gravel contents. Void ratios of gravel-sand mixtures with the same relative density (Dr=40%) are found to decrease significantly with the increase of the gravel content from 0% to about 70% and increase thereafter. But the void ratio of the sand matrix among the gravel skeleton increases with the increase of the gravel contents. Test results are as follows : for the isotropically consolidated specimen with 40% of relative density and low gravel contents (GC=0%, 20%, 40%), pore water pressure development and axial strain behavior during undrained cyclic loading show similar behavior to those of the loose sand because of high void ratio, and the specimens with high gravel content (70%) both pore pressure and strain behaviors are similar to those of dense sand. And the isotropically consolidated specimens with the same void ratio (e=0.7) and higher gravel contents show the same behavior of pore water pressure and axial strain as that of the loose sand, but for the lower gravel content this behavior shows similar behavior to that of dense sand. The liquefaction strength of the isotropically consolidated specimens with the same relative density increases with gravel content up to 70%, and the strength decreases with the increase of the gravel content at the same void ratio. Thus, it is confirmed that the liquefaction strength of the gravel-sand mixtures depends both on relative density and void ratio of the whole mixture rather than the relative density of the sand matrix filled among gravels. On the other hand, the behavior of pore water pressure and axial strain for the -anisotropically consolidated gravel-sand mixtures shows almost the same cyclic behavior of the sand with no stress reversal even with some stress reversal of the cyclic loading. Namely, even the stress reversal of about 10% of cyclic stress amplitude, the permanent strain with small cyclic strain increases rapidly with the number of cycles, and the initial liquefaction does not occur always with less than maximum pore water pressure ratio of 1.0. The liquefaction resistance increases with the gravel contents between 0% and 40%, but tends to decrease beyond 40% of gravel content. In conclusion, the cyclic behavior of gravel-sand mixtures depends on factors such as gravel content, void ratio, relative density and consolidation condition.

연약점토의 투수계수측정에 관한 연구

金芳植,李鍾昊,朴炳洙 충주대학교 산업대학원 1999 大學院論文輯 Vol.1 No.-

이 연구는 해성점토의 압밀특성에 관련된 토질정수를 효율적으로 측정하기 위한 실험적 연구이다. 이 실험에서는 시료에 완전포화를 유도하기 위하여 폐쇄식 압밀장치와 투수계수측정을 위한 Flow Pump를 설계·제작하여 초기간극비가 큰 연약점토의 압밀특성에 관련된 구성식(유효응력-간극비-투수계수 관계)을 얻고자 하였다. 실험기법에 있어서는, 시료에 배압(Back Pressure)을 가할 수 있는 Closing Ring 형식의 압밀시험기를 사용하여 하중제어식 압밀시험을 실시하여 초기간극비가 큰 연약점토에서 간극비-유효응력 관계를 얻을 수 있도록 유도하였다. 또한 이 압밀시험기에 Flow Pump를 부착시켜서 시료가 소정의 하중단계에서 암밀이 완료된 후에 일정한 유량을 인위적으로 유출시킴으로써 유출속도를 일정하게 하고, 각각의 속도에서 간극수압을 측정하여 손실수두를 측정함으로써 간극비-투수계수간의 구성관계를 얻을 수 있도록 하였다. 이 시험에서는 초기 간극비가 큰 재성형 해성점토를 시료로 사용하여 시험을 수행하고 Flow Pump의 속도를 3단계로 변화시키면서 투수계수를 측정하므로써 그에 따른 일관성 있는 우수계수의 측정여부를 확인하였으며, 기존의 하중제어식 표준압밀시험과 일정변형률 압밀시험 및 변수위 투수시험결과와 상호 비교검토하므로써 그 결과의 타당성 및 차이점에 관하여 토의하였다. This reserch is an experimental study of measuring the permeability of soft clay by using the flow pump. A consolidometer was specially built to increase the degree of saturation of specimen and the flow pump was attached to it to measure the permeability of specimen to obtain constitutive relations related to consolidational characteristics of effective stress-void ratio-permeability relationships of soft clay with high initial void ratio. In testing techique,stress­controlled consolidation tests with the consolidometer of being able to apply back pressure were performed to obtain the relation of void ratio-effective stress. Flow Pump are activated to withraw the constant rate of flow from the specimen after consolidation was finished. Thus, void ratio-permeability relation was obtained by measuring the head loss between the boundaries of the specimen caused by the seepage. For specimens, remolded marine clay with high initial void ratio was used. The flow from specimen by flow pump were changed with three different steps. Then,the effect of flow rate on the measured permeanility was analyzed. On the other hands, test results with flow pump were compared with the permeabilities measured by the conventional stress-controlled consolidation tests, constant rate of consolidation test and falling head permeability tests. Therefore, difference between testing technique were discussed and validity of consolidation tests with flow pump was evaluated.

構造物의 適正設計法에 關하여

金芳植 충주대학교 1977 한국교통대학교 논문집 Vol.10 No.1

The structure must be planned soass to satisfy all the necessary Conditions of its structure and the Condition necessary strength of its structure by using the minimum, adequate meterial and the minimum cost of installation and construction. Up to the present, we have applied the theory of the elastic limit method and Ultimate strength method for method of structure calculation. For the proper structure plan, the limit state plan method has been applied to the building construction and civil engineering constructions including the bridges since 1955. Also, the method of the limit state plan method has been developed to the case of probability theory. The formular of the limit state plan method is N ∮, and N is the means maximum calculated stress of structure and member, ∮ is means persistent load stress. Now, there are many problems to be investigated in the case of applying to the structures with limit state plan method such as the presumption of limit stress, determination of stress and load Volume, investigation of load acting stress; and it must be more studied and developed in the future.

補强土의 Dilatancy에 關한 硏究

金芳植 충주대학교 1983 한국교통대학교 논문집 Vol.16 No.1

The behavior during the stage of peak point of stress-strain curve which is called the compressive strength of soil is quite different from that during initial stage, and this can be explained by studing the deformation of planar array of sandy soil's spheres. when this element is compressed veritically and sheared on some sandy soil plane, straing can results if the spheres 0₁and 0₂ move laterally in Fig2. This motion must be accompanied by an increase in volume of the array. This is remarkable fact that a dense sand. This fact was called dilatancy to the volume of sandy soil increase effect by the concept of interlocking. In this paper, of the tendency of sandy soil increase effect by the concept of interlocking. In this paper, of the tendency of the dilatancy on reinforced sandy soil related of it's amount and size was investigated and analysed by the test of direct shear. The tendency of ditatancy of this small mass appeared same sandy soil mass.