Quantitative Evaluation of Weathering Degree through Fuzzy-AHP Method and Petrophysics Analysis for Sandstone Carvings

Study on weathering degree assessment of sandstone carvings play an important role in scientific conservation. However, current state of research on weathering assessment cannot reach the needs of scientific evaluation. In this study, the selected sandstones originate from Jurassic and, soluble salt and acid simulation experiments were carried out on standard samples. The weight, specimen surface hardness, ultrasonic velocity and water absorption are measured by means of the non-destructive methods. Furthermore, mineral composition and petrophysical properties are analyzed on small specimens in laboratory. It is revealed that the main mineral, such as quartz and feldspar, is shown by oblate and prolate in shape. Moisture content has great influence on compressive strength of rock samples. Rock porosity increases with deterioration process. The decrease of quality, surface hardness and ultrasonic velocity with increasing cycles. Conversely, water absorption capillary increase over cycles. In addition, Fuzzy-AHP method is adopted to further evaluate weathering degree on experiment samples. Results in macroscopic show that the value of weathering degree is 0.3271 for sodium sulfate solution, which is shown by moderate weathering; 0.1951 for pH = 1 sulfuric acid and 0.1060 for pH = 2 sulfuric acid, which is characterized by low weathering; 0.0516 for pH = 3 sulfuric acid and 0.0421 for pH = 4 sulfuric acid, belonging to very low weathering.

Dominant Weathering Profile Assessment of Kebo-Butak Volcanic Rocks in Gedangsari and Ngawen area, Yogyakarta, Indonesia

The Gedangsari and Ngawen area is predominantly composed of volcanic and volcaniclastic sequencesdistributed east – west direction of the northern parts of Southern Mountain. The massive tectonism as well as tropical climatein this region have been producing weathering profiles in varying thickness which inevitably affects thegeotechnical properties. This study aims to assess the dominant weathering profileof the lower part of Kebo-Butak Formation as well as evaluating the distribution of the discontinuity. In order to know the dominant weathering profile and discontinuity evaluation, this study utilizes a total of 26 panels from five stations investigated through a geotechnical data acquisition including the geological condition, weathering zones, joint distribution, and discontinuity characteristics. The result shows four types of dominant weathering profiles in lower part of Kebo-Butak Formation called as dominant weathering profile A, B, C, and D. Profile A, B, C consisted of a relatively identical weathering degree pattern of fresh, slightly, moderately, completely weathered zone with the variation of thicknesses. However, the weathering degree in profile D reached the residual soil degree controlled by more intensive joints. The fine-grained sedimentary rocks also tends to have smaller spacing, shorter persistence, and higher weathering degree of discontinuities as compared to coarse-grained sedimentary rocks.

Stability Assessment of High and Steep Cutting Rock Slopes with the SSPC Method

The stability of high rock slopes has become a key engineering geological problem in the construction of important projects in mountainous areas. The original slope stability probability classification (SSPC) system, presented by Hack, has made obvious progress and been widely used in rock slope stability analysis. However, the selection and determination of some evaluation indexes in the original SSPC method are usually subjective, such as intact rock strength and weathering degree. In this study, the SSPC method based on geological data obtained in the prospecting tunnels was presented and applied. According to the field survey and exploration of the prospecting tunnels, the weathering degree of the slope rock mass was evaluated. The empirical equation for the maximum stable height of the slope was applied to the slope stability evaluation in the presented SSPC method. Then, the slope stability probability of numerous cutting slopes in the sandstone unit was evaluated using the presented system. Results of the Geostudio software based on the limited equilibrium analysis of the investigated slopes were compared with the results obtained by the SSPC method. The results indicate that the SSPC method is a useful tool for the stability prediction of high and steep rock slopes.

Soil characteristics and erosion in the UNESCO Geopark Estrela, Portugal.

<p>In Europe, a high soil erosion risk is modelled for the Mediterranean area such as the Iberian Peninsula (e.g., EEA, 2009), while actual field data often lacks behind. Here we present the first <sup>239+240</sup>Pu soil erosion results (last ~60 years) in the UNESCO Geopark Estrela, Portugal. We investigated soils in a former vastly glaciated and a non-glaciated area. We hypothesized that erosion rates in relatively young areas (max. about 16–20 kyr) will be distinctly higher than in old areas (several 100 kyr). We assumed that soil structure, organic matter and weathering degree in younger (natural) soils are still less favourable and do not yet protect efficiently enough soils from erosion. Besides soil erosion, we explored the weathering degree of the soil material using chemical weathering indices, determined the soil surface age using meteoric <sup>10</sup>Be and looked at a broad set of physico-chemical soil characteristics of these two landscape settings.</p><p>A glimpse of our first Plutonium results indicates that the differences between these two settings are rather minor. Soil erosion rates in these natural conditions (Geopark) predominantly depend on slope. With increasing slope angle, a maximum soil erosion rate of ~1600 [t km<sup>-2</sup> yr<sup>-1</sup>] is reached. Not surprisingly, the age estimates of the soils within the formerly glaciated area confirmed the start of formation after the beginning of ice-decay. The formerly glaciated area is depleted in C and N compared to the never glaciated area. In the never glaciated area, a higher soil weathering degree is found by multiple weathering indices and an overall lower SiO<sub>2</sub> content. Although past glacial activities rejuvenated the soil material (expressed by a lower weathering degree) and affected the soil organic matter content, soil erosion susceptibility does not seem to be higher compared to never glaciated areas. Under natural conditions, a quasi-steady state with respect to soil erosion seems to be reached fairly before 20 kyrs.</p>

Weathering effects on engineering properties of Schist of Menderes Massif, West of Turkey

Schist is a metamorphic rock type that is widely exposed in the Western Anatolia. Schist of Menderes Massif is located in different locations and geological levels. The rock is mainly used as a filling and building material in the present and in foreseeable future. Usage of schist as filling materials in dams is related with their weathering degree which affects their geomechanical properties. To determinate the petrographic, chemical, index and engineering properties of the schist used as filler material in the dams/small dam crest, fresh and weathered samples of rock material were collected from quarries. The relationship between the weathering degree index and engineering properties were determined by simple regression analyses’. The results show that the studied parameters of physical and mechanical properties of the studied schist have a positive correction with weathering grade. Thus, increasing weathering grade affects the durability of the schist thereby compromising its applicability.

Study of an abnormal occurrence of Oxisols in strongly undulated relief in the south of Minas Gerais, Brazil, with support of pXRF and geomorphology

ABSTRACT Oxisols are the main soils in Brazil and they classically occur in stable and gentle geomorphic surfaces. However, in the south of Minas Gerais State, Oxisols have been observed under strongly undulated relief, a very rare condition for these soils in this physiographic region. Therefore, this work aimed to assess the elemental dynamics and relief enhanced with portable X-ray fluorescence (pXRF) spectrometry, associated to geomorphology, to understand such occurrence. The studied soils are located in Muzambinho municipality, Minas Gerais State, Brazil. Oxisol profiles were characterized in the upper third (P1), middle third (P2) and lower third (P3) of the hillslope. After morphological description, soil samples were collected in the A, AB and Bo horizons of the profiles. Physical, chemical and pXRF analyses of the soils were carried out in the laboratory. Ti and Fe content (pXRF) had a high correlation with the soil textural fractions. High weathering-leaching degrees were determined, although they occur on a steep slope where younger soils (Inceptisols) would be expected in this region. The altitudinal concordance of summits observed in the more elevated surrounding areas indicates a flat paleorelief, helping to explain this unusual occurrence. The soils’ weathering degree values decreased down the hillslope, indicating silica enrichment through runoff and subsuperficial water flux in the lower landscape positions. The pXRF analyses assisted the characterization of these old soils occurring in steep relief. It provided bases for confirming their high weathering degree indexes and detected evidences of the pre-weathering of the regolith of this very old landscape.