Effects of organic silicone additive material on physical and mechanical properties of mudstone

Chai, Zhaoyun,Kang, Tianhe,Chen, Weiyi Techno-Press 2014 Geomechanics & engineering Vol.6 No.2

Mudstone is a very common rock that, when in contact with water, can exhibit considerable volume change and breakdown. This behavior of mudstone is frequently encountered in geotechnical engineering and has a considerable influence on infrastructure stability. This is particularly important in the present work, which focuses on mitigating the harmful properties of mudstone. The samples studied are of Permian Age mudstone from Shandong Province, China. Modification tests using organic silicone additive material were carried out. The mechanisms of physical properties modification of mudstone were comparatively studied using corresponding test methods, and the modification mechanism of organic silicone additive material acting on mudstone was analyzed. The following conclusions were drawn. The surface texture and characters of mudstone changed dramatically, surface character turns from hydrophilic to hydrophobic after organic silicone additive material modification. The changes in the surface character indicate a reduction in the water sensitivity of mudstone. After modification, the shape of porosity and fracture of mudstone changed unremarkable, and the total and free expansion ratios decreased obviously, whereas the strength increased markedly.

Experimental Study on Time-dependent Behavior of Silty Mudstone from the Three Gorges Reservoir Area, China

Huai Chang Yu,Han Dong Liu,Zhi Quan Huang,Guang Cheng Shi 대한토목학회 2017 KSCE Journal of Civil Engineering Vol.21 No.3

Short-term and creep tests were performed on saturated silty mudstone obtained from the Three Gorges Reservoir area. Based on the triaxial creep test results, the variations of creep strain and creep rate of silty mudstone with time were analyzed in detail, and the differences between the axial and lateral creep parameters were quantitatively studied at different deviatoric stress levels. The longterm strength of silty mudstone was obtained. The results demonstrate that the lateral creep characteristics are more significant than the axial creep characteristics for silty mudstone in the tests. Analysis of the lateral creep characteristics of the rock is a reasonable approach to determine whether creep failure occurs in the silty mudstone. The long-term strength of silty mudstone decreases remarkably, and it is actually the lateral long-term strength of the rock. According to the triaxial creep curves of silty mudstone, a new nonlinear viscoelasto-plastic creep model was proposed by connecting in series the nonlinear viscoplastic body with the sixcomponent model. Comparing the model curves with test results, this model was determined to reflect the creep properties of silty mudstone accurately. Finally, the selection of the creep model parameters was achieved by considering the axial and lateral creep characteristics of silty mudstone.

대구경북지역 퇴적암의 포화 및 균열 유발에 따른 강도 특성

박성식,김성헌,배도한 한국지반공학회 2018 한국지반공학회논문집 Vol.34 No.12

Shale and mudstone in Daegu-Gyungbuk area have low strength and resistance to weathering compared to other rocks. Therefore, it is necessary to evaluate their strength depending on the degree of saturation and crack development. In this study, shales and mudstones were collected from several construction sites in Daegu-Gyungbuk area. Their basic material properties such as porosity, SEM, chemical component, and durability were tested. A porosity (absorptivity) of mudstone was 31% (25%), which was 6 (8) times higher than that of shale. Some mudstone was easily disintegrated with water and it consisted of highly-active clay mineral such as smectite type. These rocks were prepared by small cube specimens for unconfined compression test. An unconfined compressive strength of dry rock was compared with saturated one. Microwave oven was operated step by step to stimulate void water within a saturated rock, which resulted into high temperature and micro crack initiation within rocks. A strength of microwaved rocks was compared with operation time and crack initiation. As a result, the average unconfined compressive strength of dry and saturated shale was 62 and 33 MPa, respectively. The strength of mudstone for each condition was 11 and 4 MPa. When a rock became saturated, its strength decreased by 47% and 64% for shale and mudstone at average. In addition to saturation, a rock was in the microwave for 15 secs, its strength decreased into 49% for shale and 52% for mudstone. When a microwave oven operated up to 20 sec, a rock was crushed into several pieces and its temperature was approximately 200 degrees.

이암 절토 사면의 붕괴 요인 분석 및 대책방안 제시

박민철(Min-Cheol Park) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.4

본 연구는 O O 고속국도 공사 중 발생된 이암 절토 사면의 붕괴 요인 분석 및 대책방안을 제시하였다. 기반암인 이암에 대해 실내시험을 수행하고, 국제 기준에 의거해 공학적인 특성을 규명하였다. 그리고 설계 시 수행되었던 사면안정해석을 재검토 하였다. 또한, Swelling-Slaking 현상으로 인해 기반암인 이암의 강도열화특성을 고려한 안정해석을 추가적으로 수행하였다. 기반암인 이암에 대해 Swelling-Slacking Test 결과, 풍화내구성은 낮음-보통으로 나타났으며, 팽창변형률은 매우 낮음으로 나타났다. 설계 안정해석 검토 결과, 이암의 공학적 특성을 고려하지 않고, 한계평형해석을 이용해 실제와 상이한 결과가 나타났다. 강도열화특성을 고려한 추가안정해석 결과, 사면의 붕괴지점과 안정해석의 최대전단변형률 발생지점이 동일하게 나타났으며, 건기시 우기시 모두 기준 안전율을 만족하지 못하였다. 붕괴 사면의 대책방안으로는 사면경사완화공법이 가장 적절하였다. 유한요소해석을 통해 완화 경사를 산정하였다. 완화 경사의 현장 적용성을 위해 시추공영상촬영과 비교한 결과, 미고결된 이암의 대부분이 제거되는 것으로 나타나 미고결된 이암으로 인한 추가적인 붕괴 위험성은 현격히 저하되는 것으로 나타났다. This study analyzed the collapse course of a mudstone cut slope during the construction of a express and suggested a countermeasure. Experiments were carried cut out on bedrock mudstone to investigate the engineering characteristics and the slope stability analysis at the time the design was reviewed. In addition, stability analysis, considering the strength softening characteristics of the slope due to the Swelling-Slaking phenomenon, was also performed. As a result of the Swelling-Slaking test, the slake durability was Low-Medium, and the swell potential was Very Low. A review of the stability analysis performed at the time of the design showed different results from the actual results because LEM analysis had been performed without considering the engineering characteristics of mudstone. As a result of additional stability analysis considering the strength softening characteristics, the slope collapse point and the maximum shear strain point of the stability analysis were the same and the standard safety factor was not satisfied. As a countermeasure, a slope mitigation method was found to be most appropriate. The mitigation slope was calculated by Finite element Analysis. A comparison with BIPS to determine the applicability of a mitigation slope revealed most of the unconsolidated mudstone.

Distinct deep subsurface microbial communities in two sandstone units separated by a mudstone layer

Adriana Giongo,Taiana Haag,Renata Medina-Silva,Roberto Heemann,Leandro M. Pereira,Priscilla M. Zamberlan,Fernanda P. Valdez,Rafael R. Oliveira,Eduardo Eizirik,Adriano R. Viana,João Marcelo M. Ketzer 한국지질과학협의회 2020 Geosciences Journal Vol.24 No.3

Deep subsurface microbial communities are more abundant in coarse-grained sedimentary rocks such as sandstones than in fine-grained mudstones. The low porosity and low permeability of mudstones are believed to restrict microbial life. Then, it is expected that distinct, isolated microbial communities may form in sandstones separated by mudstones. In this context, the connectivity between microbial communities in different sandstone units can be investigated to infer evolutionary patterns of diversification in space-time, which may potentially contribute with relevant data for analyses of hydraulic connectivity and stratigraphic correlation. In this work, we used high throughput DNA sequencing of a ribosomal 16S gene fragment to characterize the prokaryotic communities found in Permian sandstone samples of the same core that are separated by one mudstone interval, in the Charqueadas coal field, Parana Basin (Southern Brazil). Our samples were collected at ~300 m deep, in porous sandstones separated by a thick mudstone package. Differences in the bacterial community structure between samples were observed for the classified OTUs, from phylum to genus. Molecular biology might be further applied as a possible tool to help to understand the spatial and temporal distribution of depositional facies, and the efficiency of low permeability rocks to compartmentalize reservoirs. Ongoing studies aim to extend the present investigation into further analyses regarding lateral changes in microbial communities present in the same sandstone units.

Research on the Formation Mechanism of Shear Zone in the Neogene Mudstone Landslide

( Xin Peng ),( Wang Tao ),( Liu Jiamei ),( Liang Changyu ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

The shear zone is the main control factor for the translational and rotational landslides.Different geometric forms of landslides were selected to analyze the process of structural change and the mechanical mechanisms of the bedding-parallel shear zone in Neogen period mudstones. The results show that there are weak layers, with high clay content, in translational landslides and rotational-translational landslides, such as those with bedding-parallel shear zone, while rotational landslides are composed of homogeneous material. The bedding-parallel shear zone can be divided into two parts: the main shear zone and the secondary shear zone. The main shear zone has an S-C fabric, the C plane has a strong scratch, and the S plane develops in high plastic mudstones. The clay contents of the main shear zone in a bedding-parallel sliding zone are greater than 50%, while the absolute content of minerals mixed with illite and montmorillonite exceeds to 20%. Creep and rapid slip are the main forms of structural deformation of the shear zone. Creep deformation mainly develops in the sliding zone with high amounts of clay particles; the microstructural adjustment of the slip zone shows no crack expansion and the clay minerals are a viscous flow. Progressive creep induced by water pressure and gravity will cause the acceleration of the creep and rapid sliding. Rapid sliding deformation, which is due to repeated shear, occurs along the fixed shear fracture-surface.

Hydrothermal synthesis of ZSM-5 zeolite using siliceous mudstone

서동수,Huynh Thanh Tuan,In-Kook Bae,Young-Nam Jang,Soo-Chun Chae,Young-Bae Chae 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.2

ZSM-5 zeolite was successfully synthesized by a hydrothermal reaction method using siliceous mudstone. The major chemical composition of siliceous mudstone is 85.85 wt.% of SiO2 and 6.99 wt.% of Al2O3, and the crystalline phases are opal-CT,quartz, smectite and muscovite. The experimental conditions were varied with the weight ratio between sodium silicate solution (SS) and siliceous mudstone (SM) from 0.8 to 1.6, the reaction temperature from 130 to 200 oC and reaction time from 12 to 30 hours. Within these experimental conditions, the most suitable combination to synthesize ZSM-5 zeolite was SS/SM = 1.2, reaction temperature = 170 oC and reaction time = 24 hours. The particle shape was a faceted-sphere and the median particle size was 5.2 μm. The BET surface area was 324 m2·g−1 after calcination at 500 oC and this value was sustained up to 700 oC.

점토함량에 따른 미고결 이암의 시간 의존적 변형 비교

장찬동 ( Chan Dong Chang ),명우호 ( Woo Ho Myoung ),이태종 ( Tae Jong Lee ) 대한지질공학회 2008 지질공학 Vol.18 No.2

점토함량에 따른 미고결 이암의 시간 의존적 변형을 비교하기 위해 측방변형이 구속된 상태에서의 일축압밀시험을 수행하였다. 미고결 이암의 변형은 응력의 증가에 따른 즉각적인 변형과 일정한 응력 하의 크리프 변형으로 구분되었다. 응력 증가분이 동일한 경우에 시간 의존적 변형은 거의 일정한 크기로 발생하였으며 응력 증가분이 증가할수록 크리프변형의 크기도 증가하여 선형점성변형의 특성을 보였다. 점토함량이 증가함에 따라 시간 의존적 변형은 증가하는 경향을 보여 점토가 이암의 시간 의존적 변형 발생에 중요한 역할을 하는 것으로 사료된다. 크리프 변형은 시간에 따라 지수함수 형태를 보여 크립 모델 중 하나인 power-law 모델로 잘 예측될 수 있었다. We conducted uniaxial consolidation tests in mudstone samples with different clay content, in order to investigate time-dependent deformation and its characteristics. A significant amount of time-dependent strain was observed at a constant stress level immediately after a jump of stress was applied. For a given mudstone, the amount of time-dependent deformation was nearly proportional to the increment of stress, suggesting a linear viscous rheology. The amount of time-dependent strain increases with clay content, implying that clay plays an important role in creep of the unconsolidated mudstone. A power-law model was suitably applied to our results, suggesting that a short-term prediction of time-dependent deformation of the mudstone is tentatively feasible.

고준위방사성폐기물 지층처분 암종 평가를 위한 경상분지 진주층 예비연구: 암상 및 광물학적 특성을 중심으로

홍성경,진광민 대한자원환경지질학회 2024 자원환경지질 Vol.57 No.4

고준위방사성폐기물(High-level radioactive waste, HLW) 지층처분은 지하 심부의 안정한 지층에 폐기물을 영구 격리하는 것이다. 전 세계적으로 고준위방사성폐기물의 지층처분 암종으로 결정질암과 더불어 낮은 투수성을 가지며 이온을 흡착하여 핵종의 이동을 억제할 수 있는 점토광물을 다량 포함하는 이암(실트암과 점토암)이 고려되거나 선정 되고 있다. 국내의 다수 육상 퇴적분지에 이암이 분포되어 있으나 지층처분 암종 평가를 위한 암상 및 광물학적 연구는 매우 부족한 상황이다. 본 연구에서는 한국지질자원연구원에서 지층처분 암종 평가를 위하여 시추한 진주층 시추공(JBH-1, 7-754 m)의 이암의 분포 양상과 광물 조성을 연구 하였다. 더불어 고준위방사성폐기물 처분장으로 선정되어 다학제적 연구가 진행 중인 스위스 Opalinus Clay와 비교 분석하였다. 40% 이상의 점토광물을 포함하는 점토암은 진주층 시추공의 상부(7-350 m)에 두꺼운 두께로 다수 협재하는 특징을 보인다. 진주층 점토암의 점토광물 특성은 심도에 따른 변화를 보이지 않으나 장석 및 탄산염 광물의 함량과 조성은 차이를 보인다. 이러한 광물 특성 변동은 핵종 거동에 영향을 미치는 공극수의 조성과 암석역학적 특성 등에 심도별 차이를 야기할 수 있다. 진주층 점토암의 점토광물 함량은 Opalinus Clay와 유사하나 점토광물 조성에서 차이를 보인다. Opalinus Clay는 스멕타이트/일라이트 혼합층 광물을 포함하는 반면에 진주층 점토광물은 높은 매몰 온도에서 변질되어 형성된 일라이트가 우세하게 관찰된다. 본 연구 결과들은 국내 고준위방사성폐기물의 지층처분 암종 연구에 유용하게 활용될 수 있을 것으로 판단된다. The geological disposal of high-level radioactive waste (HLW) involves permanently isolating the wastes in stable geological formations deep underground. Mudstone (siltstone and claystone) containing abundant clay minerals is proposed as a host rock for geological disposal of HLW because clay minerals have low permeability and high ion sorption/exchange capacity. Despite the widespread occurrence of sedimentary basins in Korea, there is a lack of evaluation of mudstone as host rocks for geological disposal. In this study, we utilized the JBH-1 borehole (7-754 m) obtained from the Jinju Formation to investigate the distribution trend and mineral compositions of mudstone. Additionally, we conducted comparative analyses with the Opalinus Clay in Switzerland considered as host rock of geological disposal of HLW. Claystone containing more than 40% clay minerals exhibit thick layers primarily in the upper section (7-350 m) of the JBH-1 borehole. While the clay minerals content of claystone does not show significant variation with depth, there are differences in the characteristics of feldspar and carbonate minerals. These mineralogical variations can led change in pore water chemistry and rock mechanical properties. The clay minerals content of claystone in the Jinju Formation is similar to that of the Opalinus Clay. However, there are notable differences in clay minerals composition. While the Opalinus Clay contains smectite-illite mixed-layer minerals, the Jinju Formation are dominated by illite indicating higher burial temperatures. This information will be useful for studying the host rock of HLW geological disposal site in Korea.

Rock Permeability Estimation from Hydraulic Injection Tests in a Sealed Borehole Interval

( Nghiep Q. Quach ),( Yeonguk Jo ),( Chandong Chang ) 대한지질공학회 2018 지질공학 Vol.28 No.1

We propose a borehole test technique to estimate permeability of rocks in borehole. The borehole tests are hydraulic injection tests such as leak-off test and hydraulic fracturing tests, which are originally conducted for stress or casing integrity assessment and not for permeability measurement. We use one-dimensional radial diffusion equation to interpret fluid injection test results in terms of permeability. We apply this technique to a leak-off test conducted at a depth of 700 m in a wellbore, where rock formation is mudstone. The estimated permeability is at an order of 10^-16 m², which is somewhat high but within the range reported for mudstones previously. Quantitative rick assessment suggests that an accurate measurement of open hole section length is important to improve reliability of results. More data may be needed to ensure the reliability of this technique. If validated, however, this technique can provide cost-effective estimation of in situ permeability without conducting independent permeability tests in borehole.