• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.10a
• /
• pp.239-246
• /
• 2005

slaking 은 굴착에 의해 노출된 암반에서 발생하는 강도저하 및 입자간의 결합력 약화에 의해 암반이 세립화하는 현상이다. 이러한 slaking은 특히 퇴적암으로 구성된 암반사변의 안정성에 영향을 미치는 중요한 인자로 작용한다. slaking에 의한 암반사면의 불안정성은 신생대의 이질암이나 미고결 응회암에서와 같이 암반 자체의 강도 저하 및 결합력 약화에 의해 발생하는 붕괴현상과 차별풍화에 의해 이암 등이 급속도로 쇄굴 및 풍화되어 상부에 놓여 있는 암석이 낙석 등의 형태로 붕괴되는 현상으로 구분할 수 있다. 본 연구에서는 이암의 차별풍화에 의해 사면의 불안정성이 유발되는 연구지역을 대상으로 풍화 및 쇄굴 속도와 slake의 상관관계를 밝히고자하였다. 이를 위하여 slake test와 slake durability test를 수행하였으며 slake durability index를 획득하였다. 실험을 통해 획득된 slake durability index를 연간 쇄굴속도와 비교하여 상관관계를 검토하였으며 기존의 연구결과와 비교하여 slake durability index를 활용하여 쇄굴 정도를 예측할 수 있는 가능성을 제시하였다.

• Geomechanics and Engineering
• /
• v.12 no.5
• /
• pp.785-801
• /
• 2017

Biopolymer treatment of geomaterials to develop sustainable geotechnical systems is an important step towards the reduction of global warming. The cutting edge technology of biopolymer treatment is not only environment friendly but also has widespread application. This paper presents the strength and slake durability characteristics of biopolymer-treated sand sampled from Al-Sharqia Desert in Oman. The specimens were prepared by mixing sand at various proportions by weight of xanthan gum biopolymer. To make a comparison with conventional methods of ground improvement, cement treated sand specimens were also prepared. To demonstrate the effects of wetting and drying, standard slake durability tests were also conducted on the specimens. According to the results of strength tests, xanthan gum treatment increased the unconfined strength of sand, similar to the strengthening effect of mixing cement in sand. The slake durability test results indicated that the resistance of biopolymer-treated sand to disintegration upon interaction with water is stronger than that of cement treated sand. The percentage of xanthan gum to treat sand is proposed as 2-3% for optimal performance in terms of strength and durability. SEM analysis of biopolymer-treated sand specimens also confirms that the sand particles are linked through the biopolymer, which has increased shear resistance and durability. Results of this study imply xanthan gum biopolymer treatment as an eco-friendly technique to improve the mechanical properties of desert sand. However, the strengthening effect due to the biopolymer treatment of sand can be weakened upon interaction with water.

• Journal of the Korean Geotechnical Society
• /
• v.28 no.11
• /
• pp.79-86
• /
• 2012

Cemented soils have been used for subbase or base materials of roads, backfill materials of retaining walls and cofferdam. Such cemented soils can be degraded due to repeated wetting and drying or various weathering actions. Unlike rocks, a standard method was not defined for evaluating the durability of cemented soils. In this study, a slaking durability test and an ultrasound cleaner were used for developing a new durability test method for cemented soils. For durability tests, cemented sands with different cement ratios (4, 6, 8, and 12%) with cylindrical specimens were prepared and then air cured or under-water cured for three days. Three-day-cured specimens were dried for one day and then submerged for one day before testing. The weight loss after the slake durability test or ultrasonic cleaner operation for 10 or 20 min was measured and used for assessing durability. When a cement ratio was 4%, the weight loss from ultrasonic cleaner test was 7-25% but that from slake durability test was as much as 30-60%. For specimens with cement ratio of more than 8%, the weight loss was less than 10% from both tests. A durability index increased with increasing a cement ratio. The durability index of under-water cured specimen was higher than that of air cured specimen. The ultrasonic cleaner test was found to be an effective tool for durability assessment of cemented sands rather than the slake durability test.

• Tunnel and Underground Space
• /
• v.23 no.3
• /
• pp.212-218
• /
• 2013

Tuff specimens were thermally treated with predetermined temperatures of 200, 400 and $600^{\circ}C$ to construct specimens simulating weathered tuff rocks. Specific gravity, absorption ratio, elastic wave velocity, uniaxial compressive strength, Brazilian tensile strength, Young's modulus, Poisson's ratio and slake-durability index were measured for pre-heated specimens. Heating of rock specimens entailed the degradation of material properties except for slake-durability index. It was found that correlations among P-wave velocity, uniaxial compressive strength, Brazilian tensile strength, Young's modulus and absorption ratio are high. Regression equations which use the P-wave velocity as an independent variable were presented to evaluate uniaxial compressive strength, Brazilian tensile strength, Young's modulus and absorption ratio.

• Proceedings of the Korean Society for Rock Mechanics Conference
• /
• 2004.04a
• /
• pp.147-155
• /
• 2004

• The Journal of Engineering Geology
• /
• v.26 no.3
• /
• pp.315-324
• /
• 2016

Because of a fissility characteristics of shale in the Gyoungsang super-group, it breaks down to debris when daylighted by construction work and causes a slope unstability. To assess the durability property of shale, a series of slake durability tests was conducted by controlling test conditions such as shape of specimen, number of specimen, revolution speed, revolution number, drying temperature and pH of submerging liquid. For the specimen shape, cube one showed relatively lower durability index than cuboid and/or fan shape one. The test with the more number of specimens showed the less durability index because of a higher friction among specimens in the drum. The durability index is linearly decreased by increasing the total number of revolution, while the revolution velocity could not affect the index. And the durability index is also decreased by increasing the drying temperature of specimen and by decreasing the pH of submerging liquid. Because the durability index of shale is almost similar to that of crystalline rocks, the disintegration characteristics of shale could not be assessed by the slake durability test recommended by ISRM, and thus a new test method by changing the total revolution number may be required for the shale having fissility characteristics.

• The Journal of Engineering Geology
• /
• v.23 no.4
• /
• pp.341-352
• /
• 2013

The physical and mechanical properties of red shale and black shale exposed in the Daegu area were investigated in tests conducted to determine unit weight, absorption ratio, porosity, ultrasonic velocity, unconfined compressive strength, point load strength, slake durability index, and deterioration characteristics. XRD, XRF, and SEM analyses were also performed on the shale specimens. While the unit weights of the two shales were similar, the absorption ratio and porosity were higher in the red shale than in the black shale. Despite the higher porosity of the red shale, the ultrasonic velocity, compressive strength, and point load strength were higher in the red shale, which is an unexpected result that may be due to the presence of fine laminations in the black shale. The deterioration rate, as determined from the point load strength and the slake durability index, increased with increasing immersion time and with the acidity of the immersion liquid. The deterioration rate was higher for the red shale than for the black shale because of the higher porosity of the former.

• The Journal of Engineering Geology
• /
• v.20 no.3
• /
• pp.311-318
• /
• 2010

We performed laboratory measurements of the mechanical properties and slake durability of Cretaceous shale from the Hwasun area, Korea, including highly weathered and fresh samples, yielding ranges of specific gravity of 2.14-2.88, dry density of 1.86-2.83(g/$cm^3$), water content of 0.12-6.36 (%), porosity of 1.33-20.49 (%), and absorption ratio of 0.51-8.5 (%). The absorption ratio shows a strong linear relation with porosity, expressed as Ab = 0.44P-0.09 (Ab: absorption ratio, P: porosity). Values of the slake durability index ($Id_2$) and point load intensity index ($Is_{(50)}$) of highly weathered to fresh shale are 90.07-99.33 (%) and 10.8-90.2(kg/$cm^2$), respectively. $Id_2$ is linearly related to $Is_{(50)}$, expressed as $Is(50)=1E-07e^{0.2033Id_2}$(kg/$cm^2$)($r^2=0.69$). This equation is a useful tool for estimating the $Id_2$ value for shale in the Hwasun area.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1999.10a
• /
• pp.345-350
• /
• 1999

In this study the results of investigation on the physical and mechanical properties of a rockfill dam body were provided. On the crest of the old Namgang dam to be excavated partially, various in-situ tests(boring with SPT, sampling of undisturbed sample, field density test, field permeability test) and geophysical investigation works were performed Rock materials, i.e., shale and sandstone, were collected, and their slake durability was evaluated using slaking durability testing method which is suggested by ISRM.

• The Journal of Engineering Geology
• /
• v.27 no.4
• /
• pp.451-462
• /
• 2017

Physical weathering caused by external forces and chemical weathering caused by the decomposition or alteration of constituent materials are the two factors that dominate the mechanical properties of rocks. In this study, a field investigation was undertaken to identify the physical and chemical weathering characteristics of the biotite granite and granitic weathered soils in Gyeongju, South Korea. Samples were collected according to their grade of weathering and subjected to modal analysis, XRD analysis, XRF analysis, physical property tests, particle size distribution tests, and slake durability tests. Modal and XRD analysis identified these rocks as biotite granite; secondary alteration minerals were not observed. Physical property tests and particle size distribution analyses indicate an average porosity of 41.28% and a sand content of > 90 wt.%. These values are somewhat higher than those of granites in general. The results of the slake durability test and XRF analyses show that the physical and chemical weathering indices of the samples vary with the degree of weathering.