Hasil untuk "Engineering geology. Rock mechanics. Soil mechanics. Underground construction"

Selaki Grace Molomo, Vhutali Carol Madanda, F. Sengani

Norite is a coarse-grained mafic igneous rock dominated by essential calcic plagioclase and orthopyroxene. Norite is known for its toughness, and it has a high compressive strength which makes it important in engineering. This paper examines the mechanical and petrographic properties of norite, including their relevance to geomechanical applications. Despite improvements in brittleness estimation, standardizing brittleness indices remains a challenge due to geological variability, incompatible petrographic techniques, and difficulties in relating mineral composition to mechanical behavior. Current brittleness models mainly rely on mechanical properties, often ignoring key petrographic factors like grain size, mineral composition, alteration, and porosity. This limits their accuracy, especially for complex rocks like norite. Few studies integrate both petrographic and mechanical data, creating a gap in fully understanding the geomechanical behavior of norite. This review was carried out by examining the origin, formation, and petrographic properties of norite, and a comparative analysis of its strength, flexibility, mineral structure, and fracture mechanics was conducted, highlighting their importance in the engineering and mining industries. The results of this study highlight how factors like strength, brittleness, and durability influence norite’s suitability for geomechanical applications in mining, tunneling, and construction. Furthermore, the results outline that the mineral composition of norite affects its strength, with quartz enhancing strength and altered minerals like feldspar, mica, and biotite weakening the rock and making it more prone to fracturing. These results are important for tunneling projects as they help predict how rocks will behave, ensuring tunnel stability and better design in underground support systems.

Bo Liu, Aydin Larestani, Kouqi Liu et al.

Shale formations have recently gained plenty of attention owing to their large amounts of reserves. Horizontal drilling and hydraulic fracturing are the proposed approaches for the development of shale formations. The extended information of the mechanical properties of shale formation is crucial for designing a successful hydraulic fracturing operation. On the other hand, the mechanical properties of such organic-rich formations are greatly affected by the mechanical characteristics of the present kerogen (organic matter), which dramatically changes during the maturation process. In this study, a Qingshankou shale sample containing kerogen type I is mechanically investigated at different maturity levels using the grid nanoindentation approach. To this end, the original immature sample is artificially matured during hydrous (HP) and anhydrous (AHP) pyrolysis. More than 930 nanoindentation tests were performed on grids of 9 × 8 on the surface of 13 samples with different maturities. The test results showed that the presence of water during pyrolysis can significantly affect the shale sample's mechanical characteristics. In higher temperatures and higher levels of maturity, the role of water becomes more pronounced. During hydrous pyrolysis, kerogen produces larger amounts of oil and bitumen, which become progressively porous. While the original sample showed a Young's modulus value of more than 48 GPa, and it fluctuated between approximately 19 and 32 GPa during the HP scenario and between 17 and 34 GPa during the AHP process. In terms of hardness, the original sample exhibited an initial value of about 1.1 GPa and more mature samples reflected hardness values in the range of approximately 0.3 and 0.97 GPa in both scenarios. According to the trends of mechanical properties during maturation, mechanical properties decreased at the initial stage of maturation and remained relatively constant during the oil window. Then, another decline was detected at the wet-gas window's closure. In the dry-gas window, HP and AHP scenarios exhibited different behaviors mainly due to the chemical structure of the kerogen residue.

Weizheng Bai, Xilin Shi, Shijie Zhu et al.

Abstract Salt cavern hydrogen storage (SCHS) is an important component of large‐scale underground hydrogen storage, with advantages such as large hydrogen storage capacity and economic feasibility. However, the uniqueness of the salt cavern structure and the inherent high risk of hydrogen storage pose a potential leakage risk. This study aims to assess the leakage risk of salt cavern hydrogen storage through a comprehensive assessment. First, the three major influencing factors of leakage risk are summarized, taking into account the unique engineering, geological conditions, and operating conditions of salt cavern storage. Subsequently, the salt cavern hydrogen storage leakage risk evaluation index system was established, and the weights of the evaluation indexes were assigned using the combination assignment method. On the basis of the two‐dimensional cloud model, a new leakage risk assessment method was proposed. In addition, the risk level assessment of the salt cavern hydrogen storage facility proposed to be constructed in Pingdingshan City, Henan Province, was carried out. Finally, corresponding risk control and preventive measures are proposed. The results of the study are useful and instructive for the safe construction of deep salt cavern hydrogen storage.

Yuriy Kirichek

The professional terminology of Ukrainian researchers and geotechnical specialists was previously formed in Russian within the framework established by the Soviet authorities, as both science and higher education were not allowed to use the Ukrainian language. Therefore, after the collapse of the Soviet Union, according to the Law on Higher Education, textbooks and national science of independent Ukraine were naturally formed by translation into Ukrainian. Meanwhile, during the Cold War, Soviet science developed behind the Iron Curtain from the West, with virtually no scientific and technical exchange. This led to significant differences in the development of entire fields of science. Now, on the way to integration into the European Union, cooperation with European colleagues has increased significantly, and mutual understanding in English is very important. The aim of this work is therefore to find ways of unifying national terminology in the field of civil engineering, particularly geotechnical engineering, to a level acceptable to our Western colleagues who are guided by European standards. The terms «civil engineering» and «geotechnics», which are relatively recent additions to our profession, are used incorrectly even in approved regulatory documents. From the point of view of English terminology, the terms «construction and civil engineering» and «geotechnics and foundation engineering» seem rather strange, because construction is a part of civil engineering and foundation engineering is a part of geotechnics. The difference between the terms «geotechnics» and «geotechnical engineering» should also be taken into account, as the former deals with the relevant scientific foundations and the latter with the application of these scientific foundations. The discipline of «soils and foundations» is known in Western universities as «foundations» and is an important component of «geotechnical engineering». At the same time, the research translation «Bases and Foundations» is never used in professional English literature, except by Russian-speaking scientists, although the word «base» is sometimes used, but not as often as in our country. Unfortunately, the misunderstanding of professional terminology has significant negative consequences, which are highlighted. The Order of the Ministry of Education and Science, Youth and Sports of Ukraine dated 14.09.2011 ¹ 1057 «On Approval of the List of Scientific Specialties» combines geotechnical and mining mechanics into the scientific specialty 05.15.09 and assigns it to the group of specialties «Development of mineral resources» 05.15.00, while geotechnical mechanics is actually the theoretical basis of geotechnics and a practical tool of geotechnical engineering. The scientific specialty 04.00.07 «Engineering Geology» is classified by the Order as a group of geological scientific specialties, although it is much more related to construction, and the specialty 03.00.18 «Soil Science» is generally classified as a group of biological scientific specialties. At the same time, the order does not include the group of specialties «Civil Engineering» at all, and the group of scientific specialties 05.23.00 «Construction» does not include the specialty «Geotechnical Engineering». It was suggested that on behalf of the Conference to address the Ministry of Education and Science of Ukraine with a proposal to introduce appropriate amendments to the Order of 14.09.2011 № 1057 «On Approval of the List of Scientific Specialities». Based on the analysis of the legislative regulation of the activities of public organisations, a new name of the national public organisation «Ukrainian Public Organisation of Soil Mechanics and Geotechnical Engineering» is proposed for discussion by the conference participants.

WANG Yiwei , LIU Run , LIANG Chao

The small-scale model test is an important method to study the bearing capacity in soil mechanics. However, the size effects of small-scale model will affect its quantitative results, so that the small-scale test can only be used for qualitative researches. In this study, 20 groups of small-scale model tests on bearing capacity of strip foundation are carried out in saturated sand foundation. The change of bearing capacity is studied by changing the foundation size, buried depth and compactness of sand. Then the discrete element analysis method is introduced, and the mechanical behavior of sand particles is simulated by rolling the resistance contact model. The bearing capacity tests on the strip foundation are simulated, and the source of the size effects of small-scale model tests and their influences on macroscopic bearing capacity are revealed from a microscopic point of view. The results show that there is a size effect in the small-scale model tests on the saturated sand foundation. The larger the foundation compactness and foundation depth, the more obvious the size effects. The size effects are the result of the combined effects of change of stress level, change of failure mode and degree of progressive failure.

leila zameni, fardin sadeghzadeh, Bahi Jalili et al.

Introduction Nitrate pollution in groundwater and drinking water reservoirs has increased alarmingly in different parts of the world. The high concentration of nitrate in surface and groundwaters is due to the excessive use of chemical fertilizers and improper disposal of wastes caused by human activities and animal manure. Due to its high mobility, nitrate anion is easily washed from the soil and enters the surface and groundwaters. If the concentration of nitrate exceeds the limit (50 mg l-1), it causes the disease of children with methemoglobinemia, as well as the formation of carcinogenic nitrosamines. Various methods have been proposed to remove nitrate. These methods besides having side effects on water, are not economically viable. In recent years, the development of effective technologies for keeping nitrates in the soil has received much attention. Adding biochar to the soil is one of the effective ways to reduce nitrate leaching. Biochar is a carbon-rich and porous substance, that is produced by heating biomass such as organic waste, animal manure, plant residues, sewage sludge, wood, etc. in limited or oxygen-free conditions. Due to its high specific surface area, high porosity, and diverse functional groups, biochar increases the water retention capacity, cation exchange capacity, and surface absorption capacity after adding it to the soil. Therefore, this research aims to investigate the effect of biochar and biochar coated with trivalent iron on the amount of nitrate absorption from aqueous solution. Materials and Methods Biochar can be produced from materials with low economic value and is a suitable and inexpensive adsorbent for nitrate removal from water sources. According to the studies conducted for biochar production, the temperature and duration of storage in the furnace are the most important factors controlling the quality and strength of biochar in nitrate removal. In this research, four types of rice straw, rice husk, sugarcane bagasse, and dicer wood chips were used to produce biochars. First, the samples were passed through a 2 mm sieve and dried in an oven at 70°C for 24 h. Then they were converted to biochar for 3 h at 300 and 600°C in an electric furnace under oxygen-free conditions. To determine the best adsorbent with maximum nitrate absorption, 0.5 gr of each adsorbent was weighed and poured into a 50 ml centrifuge tube. Then, it was contacted at a constant time (60 min) at an initial concentration of 50 mg l-1 of nitrate solution. After determining the best adsorbent, kinetic experiments were done to determine the equilibrium time, optimum pH, and adsorbent dosage. The adsorption isotherms were conducted for soil, rice husk 300˚C (RSB 300), and Fe-coated RSB 300. Results and Discussion The results showed that among the eight types of biochar produced at two temperature conditions of 300 and 600 ˚C, RSB 300, with the initial concentration of nitrate solution of 50 mg l-1 and contact time of 60 min, had the most amount of nitrate absorption. The kinetic experiments were continued on this type of biochar. The kinetic experiment results showed adsorption nitrate with an initial concentration of 50 mg l-1 an equilibrium time of 90 min, pH 7, and an adsorbent dosage of 1.25 g l-1 was 23580 mg kg-1. The result of the adsorption isotherms study showed that the adsorption of nitrate on RSB and Fe-coated RSB were fitted to the Langmuir isotherm model. This result indicates the uniform or single-layer distribution of active sites on the absorbent surface. The maximum adsorption capacity of nitrate by RSB and Fe-coated RSB were 38.16 and 43.66 mg g-1, respectively. ConclusionThe use of cheap absorbents can be a suitable solution for removing environmental pollution. In general, biochar can absorb pollutants and nutrients by its potential physicochemical properties, including high specific surface area, high porosity, high cation and anion exchange capacity, high surface charge density, low volume mass, and the presence of functional groups. The results showed that among the eight types of biochar tested, RSB with the initial concentration of nitrate solution of 50 mg l-1 and contact time of 60 min, had the highest absorption rate. The optimal conditions for nitrate absorption are estimated at 90 min of contact time, pH 7, and adsorbent dosage of 1.25 g l-1. The results showed that wastewater treatment by surface absorption process using biochar produced from vegetable waste is a very useful and effective method. Besides, the results of isotherm adsorption on the nitrate adsorption test data by biochar produced from RSB and Biochar Fe-coated RSB showed that nitrate adsorption on these adsorbents according to its correlation coefficient (R2=0.994) is consistent with the Langmuir isotherm model. The maximum absorption capacity RSB is 38.16 mg l-1, which is more absorbable than other studies. Now, when the above biochar was coated with Fe, the maximum nitrate absorption capacity increased by 43.66 mg g-1, which is a very high absorption. It can be concluded that RSB, especially when it has a Fe-coating, is a suitable adsorbent for removing nitrate from water. Therefore, it is suggested to investigate the effect of biochar covered with different cations on the mobility of other pollutants that are in anionic form.

Lie Kong, Junlong Shang

Mineral-filled fractures (rock veins) are common in the Earth's upper crust. Understanding the cracking and deformation behaviour of the mineral-filled fractures is of fundamental value for wide applications such as earthquakes, landslides, and the stability of underground infrastructure. In this study, we simulated the cracking behaviour of mineralised fractures under a direct-shear load using the discrete element method (DEM). A synthetic rectangular numerical specimen sized 5 cm by 5 cm was considered. An analogous vein was embedded along the middle line of the specimen. We calibrated the mechanical properties of the vein and host rock materials based on the experimental tests of a veined rock from the Cornwall area in England, UK which is a potential area for constructing the geological disposal facility (GDF) for nuclear waste. We analysed results including cracking dynamics, loading curves, and crack partitions in/along different material phases (i.e., host material, vein, and host-vein interface). We envisage that this study could provide valuable information regarding the activation and deformation of mineralized fractures especially from a micro-scale perspective. The mineral vein (mineral-filled fracture) is a unique geological structure that widely exists in geoformations. Generally, the mineral veins are created within the pre-existing fractures that were earlier formed by geo-stresses and crustal movement. The existence of fractures in the geo formations is very important for wide geoengineering and geomechanical applications such as safety and stability of underground construction, and prediction of earthquakes and landslides. In the literature, many works have investigated the effect of fractures or weak interfaces on the mechanical and hydromechanical behaviours of rock formations [1-6]. Consensus has been reached that the fracture is critical in geomechanics because it often dominates the mechanical and hydro-mechanical behaviour of rock. However, in the current geomechanics and rock mechanics studies, the fracture is often considered as a linear interface. The presence of mineral veins in fractures was often ignored or less investigated. While is revealed that the existence of the mineral vein will alter the mechanical and hydraulic properties of the host rock by changing the mechanical properties (strength, modulus, friction etc) and hydraulic properties (void/apertures, etc) of the host fractures [7], how the mineral veins affect the activation and deformation behaviours of pre-existing fracture is still unclear. It is important to understand the activation and deformation of the mineralised fractures which is fundamentally important for rock and geological engineering projects. The knowledge obtained through the proposed works is beneficial because it will allow us to make use of the mechanisms that could contribute to techniques that could either improve efficiency (e.g., enhancing the stability) or migrate the unwanted risks (e.g. severe collapse/leakage of tunnels and caverns).

W. Lin, Y. Sakai, N. Kamiya et al.

Determination of in situ stress states is one of the most important issues for rock mechanics, rock engineering, and geomechanics, but difficult challenges in its measurement technique remain. In the past two decades, we have conducted more than ten case studies related in-situ stress measurements by a core-based method called anelastic strain recovery (ASR) technique in both oceanic and continental deep drilling projects. The case studies covered a wide range in terms of rock types, retrieved depths of core samples, and research backgrounds. Through learning by trial and error of the applications of the ASR technique, we have established a practical test protocol and data processing procedure for determining three-dimensional in-situ stresses from the ASR measurement data. In this paper, we review previous case studies of stress measurements using the ASR technique and summarize the detailed test procedures, and suggest a standard test protocol for both oceanic and continental deep drilling project. In addition, we will also address challenges for the future. Stress state is a key parameter to understand plate tectonics, structural geological setting of subduction zones and to ensure safe and efficient developments of underground energy resources in great depths. Therefore, determination of in-situ stress states is one of the most important issues for rock mechanics, rock engineering, and geomechanics, but difficult challenges in its measurement technique remain. Stress measurements are carried out both in tunnels with large overburdens in civil and mining engineering and in deep boreholes for natural underground resources developments and for scientific investigations. Here, we focus on the in-situ stress measurements in both deep ocean drilling and continental (onshore) drilling in this paper. In deep boreholes, methods of stress determination can be divided as downhole measurements such as hydraulic fracturing / extended leak off test, stress analysis using borehole breakouts and drilling induced tensile fractures, and core-based techniques. As the core-based techniques, Anelastic Strain Recovery (ASR), Diametrical Core Deformation Analysis (DCDA), Acoustic Emission (AE), Differential Strain Curve Analysis (DSCA), Deformation Rate Analysis (DRA) have been proposed (Amadei and Stephansson, 1997; Zoback et al., 2003; Zoback, 2007; Zang and Stephansson, 2010; Ito et al., 2013). In the past two decades, we have successfully conducted more than ten case studies of in-situ stress measurements by the core-based method called anelastic strain recovery (ASR) technique in both oceanic and continental deep drilling projects in geoscience and/or geoengineering areas. In this paper, we review previous case studies of stress measurements using the ASR technique, summarize the detailed test procedure, and suggest a standard test protocol mainly for deep boreholes.

Zheng Fang, Mian Chen, Jiaxin Li et al.

The Southwest Tarim Depression is an important production succession area of the Tarim oilfield, but in the course of exploration, due to the complexity of ultra-deep fracture formation, the mechanism of wellbore instability is not clear, and reasonable drilling fluid technology countermeasures cannot be proposed, which brings great challenges to efficient drilling. In this paper, starting from the lithology, physical and chemical properties, microstructure and rock mechanics characteristics of ultra-deep fracture formation in southwest depression, the mechanism of wellbore instability is clarified, a suitable calculation model of wellbore stability is established, and a reasonable safe drilling fluid density window is proposed. Technical countermeasures of drilling fluid are put forward from the perspective of engineering geomechanics. The results show that the ultra-deep fractured formation is dominated by dolomite, showing weak water-sensitive characteristics and developing multi-scale fractures, which makes drilling fluid invade the formation and cause wellbore collapse. By calculating the corresponding sealing coefficient plate and safe drilling fluid density window, it is clear that when the sealing coefficient is above 0.7, the diameter expansion ratio (≤ 15%) can be kept within the safe construction range. The appropriate sealing materials can be selected to improve the sealing coefficient of drilling fluid, which can also increase the sealing property of drilling fluid and improve the condition of wellbore instability in ultra-deep fractured formations. The geological conditions of the ultra-deep fractured formations in the southwest Tarim depression are highly complex, characterized by widespread natural fractures and significant differences in structural stress. The presence of fractures, joints, and other weak planes exacerbates the anisotropy of formation strength, affecting wellbore stability. Instabilities in wellbores within fractured reservoirs are more severe compared to conventional reservoirs [1-2]. The lubricating effect generated by drilling fluid infiltration into the formation leads to a reduction in rock strength [3]. Consequently, frequent occurrences of wellbore instability accidents when drilling encounters such formations greatly impede the efficient development of oil and gas resources in the southwest Tarim depression.

Zhanlin Mu, Feng-xi Zhou

The estimation of grouting pressure and slurry diffusion range in grouting engineering is an urgent engineering problem to be solved, as the diffusion behavior of slurry is extremely concealed and the geological structure of underground rock and soil is complex. Taking power-law slurry as the research object, the seepage movement equation of time-varying slurry is obtained by analyzing the laminar flow movement of the slurry in the circular pipe. A cylindrical diffusion model considered the displacement of slurry-water-gas is established based on the theory of seepage in unsaturated porous media. Combined with the seepage motion equation, relevant boundary conditions and interface conditions, the power-law slurry diffusion equation is obtained, which takes into account the principal grouting parameters and mechanical parameters. At the same time, the rheological characteristics and viscosity time-varying experiment of slurry are carried out to obtain the rheological and consistency coefficient time-varying curves of slurries with different water-cement ratio, as well as corresponding function expressions. Then the numerical examples are used to analyze the mechanism of different factors affecting the slurry diffusion behavior. The above analysis and experimental results confirm the effectiveness and applicability of the research results, which can provide necessary theoretical support and technical reference for the design and construction of grouting projects in unsaturated soil areas.

Jianhong Chen, Yakun Zhao, Zhe Liu et al.

A rockburst is a geological disaster that occurs in resource development or engineering construction. In order to reduce the harm caused by rockburst, this paper proposes a prediction study of rockburst propensity based on the intuitionistic fuzzy set-multisource combined weights-improved attribute measurement model. From the perspective of rock mechanics, the uniaxial compressive strength σc, tensile stress σt, shear stress σθ, compression/tension ratio σc/σt, shear/compression ratio σθ/σc, and elastic deformation coefficient Wet were selected as the indicators for predicting the propensity of rockburst, and the corresponding attribute classification set was established. Constructing a model framework based on an intuitionistic fuzzy set–improved attribute measurement includes transforming the vagueness of rockburst indicators with an intuitionistic fuzzy set and controlling the uncertainty in the results of the attribute measurements, as well as improving the accuracy of the model using the Euclidean distance method to improve the attribute identification method. To further transform the vagueness of rockburst indicators, the multisource system for combined weights of rockburst propensity indicators was constructed using the minimum entropy combined weighting method, the game theory combined weighting method, and the multiplicative synthetic normalization combined weighting method integrated with intuitionistic fuzzy sets, and the single-valued data of the indicators were changed into intervalized data on the basis of subjective weights based on the analytic hierarchy process and objective weights, further based on the coefficient of variation method. Choosing 30 groups of typical rockburst cases, the indicator weights and propensity prediction results were calculated and analyzed through this paper’s model. Firstly, comparing the prediction results of this paper’s model with the results of the other three single-combination weighting models for attribute measurement, the accuracy of the prediction results of this paper’s model is 86.7%, which is higher than that of the other model results that were the least in addition to the number of uncertain cases, indicating that the uncertainty of attribute measurement has been effectively dealt with; secondly, the rationality of the multiple sources system for combined weights is verified, and the vagueness of the indicators is controlled.

Guiming Dong, Ying Wang, Hongbin Zhan et al.

Objective Groundwater numerical models often have uncertainties due to the complexity of the hydrogeological conditions and the economic and time constraints in collecting a sufficiently large dataset as inputs for conducting modelling exercises. In the past 50 years, stochastic methods have been one of the main methods of uncertainty analysis. The interval uncertainty is different from the stochastic uncertainty, and it considers the hydrogeological parameters as the intervals (ranges) without considering their stochastic properties. Methods From the perspective of interval uncertainty, a numerical simulation method based on first-order perturbation expansion was proposed for simulating unsteady two-dimensional confined flow with known hydrogeological parameters as intervals in this paper.The proposed method is implemented based on GFModel, a three-dimensional (3D) numerical simulation platform for groundwater flow and pollutant migration. Results The analysis shows that the relative error can be controlled within 10% when the parameter change rate is less than 0.1. The computational efficiency of the proposed method is obviously higher than that of the continuous sampling method with equal spacing. Conclusion This method allows the interval of the head or water budget to be calculated without the requirement for detailed statistical information (which is usually unavailable in advance) if the intervals of hydrogeological parameters are known.It provides a theoretical basis for decisions on the use and protection of groundwater resources.

Shan Tong, Kristin M. Sample-Lord

Polymer-enhanced bentonites for geoenvironmental containment barriers, such as bentonite-polyacrylic-acid composite (BPC), generally have low hydraulic conductivity (e.g., k < 10−10 m/s) even when exposed to aggressive waste solutions. However, understanding of diffusion and membrane behavior properties of enhanced bentonites and associated impacts on coupled contaminant transport through the barrier remains limited. In this study, hydraulic conductivity (k), effective diffusion coefficients (D*), and membrane efficiencies (ω) were measured for BPC with 3.2 % polymer content (by mass; referred to as BPC-3.2). Tests were performed with potassium chloride (KCl) solutions ranging from dilute (2.5 mM) to aggressive (400 mM) concentrations. As concentration increased, D* increased by a factor of three, ω decreased by two orders of magnitude, and k remained relatively low (1.2 × 10−11 to 2.9 × 10−11 m/s). The experimental results were paired with an existing coupled solute transport model to evaluate the significance of membrane behavior and diffusion on predicted total solute flux through a geosynthetic clay liner (GCL) and a GCL overlying an attenuation layer. The predicted mass flux was diffusion dominated, with the diffusive flux greater than the advective flux by one to two orders of magnitude. Membrane behavior reduced predicted total solute flux through the GCL by 5.8 to 61 %. The results demonstrate the role of coupled solute transport in the long-term performance of bentonite barriers, and advance understanding of contaminant transport in BPC.

Wang Zhibin, Yang Liyun, Qian Guian et al.

In order to study the relationship between the tensile and compressive strength of the concrete commonly used in engineering and the size of specimen, a statistical model of the size effect on concrete strength was established based on the generalized weakest chain formula proposed by Lei recently, assuming that the distribution of the internal defects in concrete follows the uniform distribution or the Poisson distribution. It realizes the prediction of the strength of small-scale concrete specimens to the strength of full-scale members under the condition of a given failure probability. The analysis of concrete strength data from the three published cases shows that: Under the assumption of uniform distribution of defects, the statistical method of size effect can well reflect the relationship between the tensile strength and size of ordinary concrete and RPC.The internal defect distribution of RPC concrete is closer to a uniform distribution, and the relationship between its compressive strength and size can also be described by the statistical method of size effect.

مهدی اسماعیلی, سپیده کلاته جاری, فواد فاتحی et al.

سابقه و هدف: امروزه ، کودها یکی از عوامل موثر بر عملکرد گیاهان هستند ، اما استفاده زیاد از آنها ، به ویژه اگر با روشهای مدیریت نامناسب مانند سوزاندن بقایای گیاهان ترکیب شود ، مواد آلی خاک را به شدت کاهش می دهد. همچنین استفاده طولانی مدت از کودهای شیمیایی منجر به شستشو و آلودگی آب های زیرزمینی می شود. استفاده از کودهای زیستی برای کاهش استفاده از کودهای شیمیایی و افزایش بازده محصول ، یک استراتژی مهم برای حرکت به سمت کشاورزی پایدار است. تاکنون هیچ تحقیقی در مورد تأثیر ورمی کمپوست و ورمی واش بر رشد و نمو گیاه گازانیا انجام نشده است. بنابراین مطالعه حاضر به منظور بررسی اثرات ورمی کمپوست و ورمی واش بر رشد و نمو گیاه گازانیا انجام شد.مواد و روش‌ها : به‌منظور بررسی تاثیر کودهای زیستی بر خصوصیات مورفولوژیکی و فیزیولوژیکی گل گازانیا آزمایشی در سال 1397 در گلخانه‌ گروه زراعت دانشگاه تهران در کرج انجام شد. ورمی‌کمپوست در 4 سطح (شاهد، 20، 40 و 60 درصد حجمی بستر کشت) و ورمی‌واش در 4 سطح (شاهد، 50، 100 و 200 میلی‌گرم در لیتر) به‌صورت فاکتوریل در قالب طرح بلوک کامل تصادفی استفاده شدند. صفات ارتفاع بوته، تعداد گل، قطر گل، حجم ریشه، وزن تر و خشک اندام هوایی، وزن تر و خشک ریشه، مقدار کلروفیل، میزان قند محلول، غلظت عناصر پتاسیم، نیتروژن و فسفر برگ مورد بررسی قرار گرفتند. تجزیه و تحلیل آماری داده ها با استفاده از نرم افزار SAS نسخه 9.1 و مقایسه میانگین ها با استفاده از آزمون چند دامنه دانکن در سطح احتمال 5٪ انجام شد.یافته‌ها: تیمارهای ورمی کمپوست و ورمی واش اثرات چشمگیری بر خصوصیات مورفولوژیکی و فیزیولوژیکی گیاه گازانیا داشتند. اثر متقابل ورمی کمپوست و ورمی واش برای همه صفات مورد مطالعه به جز غلظت فسفر معنی دار بود. بیشترین تعداد گل (10 گل) در تیمار 60٪ ورمی کمپوست و ورمیواش با میزان 100 میلی گرم در لیتر مشاهده شد. از نظر تعداد و قطر گل بین 40 تا 60 درصد حجم ورمی کمپوست و همچنین بین 100 تا 200 میلی گرم در لیتر ورمی واش تفاوت معنی داری مشاهده نشد. بنابراین ، افزایش مقدار ورمی کمپوست و ورمی واش تا حدی باعث افزایش خصوصیات تولید مثل گیاه می شود و بالاتر از آن حتی می تواند صفات مربوطه را کاهش دهد. با افزایش حجم ورمی کمپوست از 20٪ به 40٪ ، حجم ریشه گلهای گل آفریقایی به طور قابل توجهی تغییر کرد. وزن تازه و خشک شاخه ها نیز پاسخی مشابه به تیمارهای ورمی کمپوست و ورمی واش نشان داد. با افزایش حجم ورمی کمپوست از 20 به 40٪ ، قند محلول به طور قابل توجهی در گیاه گازانیا افزایش می یابد. ورمی کمپوست و ورمی واش باعث افزایش کلروفیل در گازانیا شدند. بیشترین مقدار کلروفیل b در تیمار ورمی کمپوست با حجم 60٪ و 50 میلی گرم در لیتر ورمی واش مشاهده شد. نتیجه‌گیری: بر اساس نتایج آزمایش ، ورمی کمپوست و ورمی واش ، با جذب مواد مغذی موثر و جذب و ذخیره سازی آب زیاد ، صفات تولیدمثل گیاه گازانیا را افزایش داد.اثر تیمار ورمی‌کمپوست بر صفات مورد بررسی گازانیا بیشتر از تیمار ورمی‌واش بود.تیمار 40 درصد حجمی ورمی‌کمپوست و 200 میلی‌گرم در لیتر ورمی‌واش مناسب‌ترین تیمار جهت بهبود رشد گیاه گازانیا بود.

Gao Jing, Zhou Weibo, Liu Shuwu et al.

In order to adapt to the construction and development of informatization and digitization of engineering survey industry, a method of rock mass quality classification based on 3D geological modeling analysis is proposed. Based on a hydropower station as an example, this paper build a refinement 3D geological visualization model, simulate and analysis engineering geology of the hydropower station from the perspective of the three-dimensional digital. According to features of rock mass damage and elastic-plastic mechanics of dissipation energy principle, which gives the optimize evaluation index and method of rock mass quality classification in water resources and hydropower engineering, endowed with classification attribute values of each level and restructured model shows the spatial distribution characteristics of rock mass quality. In conclusion, this method improves the efficiency and intuitiveness of the engineering geology analysis and engineering rock mass quality classification. Furthermore, the 3D digital evaluation method was verified more rationality and intuitiveness in geological engineering comparing with traditional 2D geological analysis method.

Manuel Cueto, C. López-Fernández, L. Pando et al.

Wen-Jing Sun, Yu-Jun Cui

It is well-known that a close link exists between soil-water retention curve (SWRC) and pore size distribution (PSD). Theoretically, mercury intrusion porosimetry (MIP) test simulates a soil drying path and the test results can be used to deduce the SWRC (termed SWRCMIP). However, SWRCMIP does not include the effect of volume change, compared with the conventional SWRC that is directly determined by suction measurement or suction control techniques. For deformable soils, there is a significant difference between conventional SWRC and SWRCMIP. In this study, drying test was carried out on a reconstituted silty soil, and the volume change, suction, and PSD were measured on samples with different water contents. The change in the deduced SWRCMIP and its relationship with the conventional SWRC were analyzed. The results showed that the volume change of soil is the main reason accounting for the difference between conventional SWRC and SWRCMIP. Based on the test results, a transformation model was then proposed for conventional SWRC and SWRCMIP, for which the soil state with no volume change is taken as a reference. Comparison between the experimental and predicted SWRCs showed that the proposed model can well consider the influence of soil volume change on its water retention property.

В статье рассматривается строение и стратиграфическое расчленение палеозойского разреза параметрической скважины Курган-Успенская-1, пробуренной в пределах Вагай-Ишимской впадины. Скважина глубиной 2503 м вскрыла разрез в диапазоне фаменский ярус верхнего девона-нижневизейский подъярус нижнего карбона. Возраст отложений (известняков, глинистых известняков, обломочных пород) обоснован комплексами органических остатков (фораминифер, водорослей, брахиопод, мшанок), которые приводятся. По таксономическому составу эти комплексы лучше всего сопоставляются с таковыми Центрального Казахстана, а также Кузнецкого бассейна Ангариды. Разрез, вскрытый скважиной, разбит на блоки многочисленными взбросами по крупной флексуре.