Results Of Geological Surveys Research Articles

Characterization of Underwater Landslides in Krui Waters, Lampung-Indonesia using Shallow Seismic and Sonar Data

Abstract Krui Waters, Lampung, Indonesia, is an area that has the potential for a tsunami disaster. Local tsunamis can be caused by underwater landslides owing to ground movement and gravitational forces. Imaging underwater conditions using sonar and shallow seismic systems is an interesting research topic for geological disaster researchers. Underwater landslides are very important for disaster mitigation, especially for tsunami prediction. This research aims to identify the characteristics of underwater landslides around Krui Waters, Lampung, Indonesia, using imaging analysis methods from sonar data and a sub-bottom profiler (SBP). The underwater landslide phenomenon in this area is still not known in detail, and therefore requires further research. All data were obtained from the results of hydrographic, geological, and geophysical surveys of RV Baruna Jaya IV in 2020. The sonar data shows surface characteristics such as the presence of Furrows (Gravel Waves), Cobble (Boulder), as well as Canyons and landslides or mass movements rocks. SBP data show the characteristics of the seabed in the form of a canyon with a slope greater than 160. Finally, the morphological characteristics and features obtained could possibly be a potential source of local tsunamis owing to the high slope.

Investigation of Landslide by Comprehensive Geophysical Exploration in Northeast Chongqing: Taking Xiawafang Landslide as Example

Aiming at the characteristics of geological structure of Xiawafang landslide in Wuxi County, northeast Chongqing, high density resistivity method and seismic image method are used to comprehensively analyze the differences between conductivity and impedance of rock stratum in this area. At the same time, the geological survey results and drilling data are taken as the basis. With the fusion of geology-geophysics analysis and interpretation, this paper shows the characteristics of geological structure and spatial distribution in the exploration area, and landslides can be analyzed according to their mode of deformation and destruction, which provides a basis of comprehensive geology-geophysics interpretation for the treatment of geological landslide.

Numerical Simulation of Seepage Surface and Analysis of Phreatic Line Control from a Fine-Grained Tailings High Stacked Dam under Complicated Geography Conditions

Background: It is adverse for the safety of a tailings dam to use fine-grained tailings as the materials for a high tailings dam because of the low penetration coefficient, the slow consolidating velocity, and the bad physical mechanical property. Furthermore, with the influence of complicated geography conditions, the phreatic line will be increased enormously when encountering special conditions, which directly affect the safe operation of the tailings dam. Methods: In this study, based on the engineering, geological, and hydrogeological conditions and survey results of a tailings dam, a 210 m fine-grained tailings dam located in three gullies was selected and used to simulate the three-dimensional seepage field of a tailings dam under a steady saturated state by using the finite element software MIDAS GTS. The permeability coefficient was inverted, the seepage field of the project under different working conditions was simulated, and the position of the phreatic line was obtained. The controlled position of phreatic lines was determined by combining the seepage field with the stability requirements. Results: Back analysis could accurately reflect the actual permeability coefficient of each partition of tailings dams. Due to the multiple areas of seepage accumulation, large valley corners, and narrowing of the dam axis, the phreatic line of the shoulder region was elevated by 2~3 m compared to the surrounding area and was thereby the most critical region of the tailings dam seepage control. The stability requirements and minimum controlled position of the phreatic line requirements could be met when the controlled position of the phreatic line was 23 m. Conclusion: This study revealed the key areas and reasons why the tailings dam’s phreatic line is prone to be uplifted under complicated geography conditions. It was very critical to control the local phreatic line by adopting local horizontal seepage drainage measures or radiation wells in the key areas of the tailings dam to ensure the safety of the tailings dam. In addition to strengthening the daily monitoring of the key areas and the exfiltration facilities of the tailings dam, it is recommended to carry out determination tests of the permeability coefficient and particle size at regular intervals. The findings could provide countermeasures for seepage control.

Inert Gas—A New Geochemical Technology for Natural Gas Hydrate Exploration in Midlatitude Permafrost

The development of geochemical exploration technologies unaffected by marsh microorganisms is necessary to improve the prediction of wells and explore for natural gas hydrates in mid-latitude permafrost areas. Here, we examine the potential of inert gas as a new tool for the investigation of gas hydrates in permafrost areas. The study area, 150 km2 in size, is situated in the alpine wetland landscape of the Qilian Mountains. The sampling density and depth were 2 points/km2 and 60 cm, respectively. In total, 300 soil and headspace gas samples were collected. The chromatographic backflush technique was used to analyze the inert gases helium (He) and neon (Ne) in the headspace gas samples. A comprehensive interpretation was conducted based on geological and geochemical survey results. We propose a geogas migration mechanism of inert gases in the soil above the natural gas hydrate deposits. The inert gas anomalies near the ground surface of the Muli coalfield in the Qilian Mountains, derived from the deep hydrate deposits and fault structure, are not affected by marsh microorganisms. Thus, inert gas anomalies are practical tools for natural gas hydrate exploration in permafrost areas.

POSSIBLE EVIDENCE FOR THE EXISTENCE OF VOLCANOGENIC MAGMATISM IN THE SINYAYA RIVER BASIN AT THE SOUTHERN FLANK OF THE VILYUI SYNECLISE

The results of different-extension geological survey, exploration and thematic work methods show that the Vilyui syneclise is relatively amagmatic. However, the recent factual evidence in this region indicates the occurrence of magmatism of a different composition and age. This evidence includes kimberlite indicator mineral found in the sedimentary cover of the syneclise. Kimberlites or magmatic rocks of a different composition are not yet known there, so that any other signs of the presence of this type of rocks therein are of importance. As such a sign the authors consider a boulder of metamorphic rock found in the Archean greenstone succession in the lower reaches of the Sinyaya River at the southeastern flank of the Vilyui syneclise. The rock is similar in its mineral composition to garnet-staurolite-kyanite schist typical of the Barrovian metamorphic rocks series. The rocks of this mineral composition are common in the greenstone belts of the Aldan-Stanovoy Shield. In particular, they are typical of the Tungurchin metapelite unit of the TemulyakitTungurchin greenstone belt exposed in the western part of the shield. The straight line distance between the sratotype area of the Tungurchin Formation development and the place where the boulder was found is more than 600 km southwest of the Sinyaya River. So it is unlikely that the boulder was just transported along the Lena River basin and then to the Sinyaya River by, for example, the Quaternary glacial ice. A more realistic way the boulder appeared in the place where it was found would be its transportation from depth by volcanic pipe, i.e. the boulder is a xenolith from volcanic pipe. The volcanic pipe can be within a radius of a few tens of kilometers or less. The Archean basement therein lies at at a depth of a few hundreds of meters to 100 meters which implies transportation of so large xenolith to the surface during the volcanic pipe formation. Therefore, it can be implied that magmatic events occurred in the form of the Jurassic-Cretaceous or probably Middle Paleozoic volcanic pipe intrusion into the Sinyaya River basin area where the metamorphic xenolith was found.

On the coherence of the formation of containing and ore containing Precambrian formations Orikhovo-Pavlograd suture zone of the Ukrainian shield

This paper presents the results of detailed geological and structural surveys within the Orikhovo-Pavlograd suture zone of the Ukrainian shield. In the northern part of the Orikhovo-Pavlograd suture zone of the Ukrainian shield, dislocation structures of several generations are identified, which differ from each other in spatial placement and R-T values of material filling. The structures of the first five generations are formed by mineral parageneses from granulite to green shale facies of metamorphism; their age is connected to the time range of 3.6–1.8 billion years. Later dislocation structures are postmetamorphic. At the micro-meso levels of the organization, the selected structures are represented by striation, shale, linearity, cleft, cracks, etc.; at the macro level, they are represented by viscous and brittle faults. Systematized data on the structural and material organization of U-, Th-containing Pivnichno Tersyansk folded shape according to the principle of hierarchy of geological structures. It is shown that this U-, Th-perspective object is a highly ordered propulsion structure. That is, its formation was provoked by Paleoproterozoic displacements and occurred synchronously with the formation of containing geological bodies by turning up existing Precambrian formations with the creation of new structural and material parageneses. An idealized model of forming a single U-, Th-perspective structure is created, this will contribute to the search for uranium-thorium mineralization and the expansion of the mineral resource base of nuclear energy in Ukraine.

Geological Hazards of Housing Development of a Pliocene Terrace Land Plot in the City of Rostov-on-Don

Introduction. In Rostov-on-Don the industrial and civil construction is carried out under a number of geological hazards: soils subsiding deformations, landslides, underfloodings, suffusions. Building up the new urban districts has always led to the groundwater surge. The Pliocene terrace building conditions in the eastern part of the city are characterised by the high risk of underflooding due to the shallow groundwater, low hydraulic gradients and water permeability of soils. The data on the present state of the groundwater level is not published in the media. Based on the materials on the territory geological structure and hydrogeological conditions, as well as on the numerical hydrogeological modeling, the present paper aims to investigate the groundwater balance determining factors and to develop the geofiltration monitoring recommendations for constraining the underflooding.Materials and methods. The geological structure and hydrogeological conditions of the territory were analysed using the published reading and graphical materials, as well as the engineering and geological survey results. The aquifers’ geometrical parameters analysis and the spatial data visualisation were made by means of the QGIS geographic information system. For creating and analysing the numerical geofiltration models, the Visual Modflow software product of Aquaveo company was used.Research results. The natural and technogenic geofiltration state of the territory under investigation had been forming for many years. The study of the designed numerical hydrogeological model indicates on the high risk of local underflooding as well as defines the conditions of its spreading throughout the entire territory. The role of the ravine-gully system that drains the aquifer and constrains the underflooding has been assessed. To control the territory groundwater balance and to specify the aquifers’ parameters, the layout of the observational hydrogeological wells network has been developed. Discussion and conclusion. The existing groundwater balance is vulnerable. Building up the territory is highly likely to cause additional infiltration of technogenic water and to lead to underflooding. The territory development project should envisage the geofiltration process monitoring and groundwater draining solutions.

Debris Flow Classification and Risk Assessment Based on Combination Weighting Method and Cluster Analysis: A Case Study of Debris Flow Clusters in Longmenshan Town, Pengzhou, China

Debris flows can damage infrastructure and threaten human life and property safety, especially in tourist attractions. Therefore, it is crucial to classify and evaluate the risk of debris flows. This article takes 14 debris flows in Longmenshan Town, Pengzhou, Sichuan, China, as the research object. Based on on-site geological surveys, combined with drone images and multiple remote sensing images, the essential characteristics of each debris flow are comprehensively determined. A total of nine factors are used as the primary indicators affecting the risk of debris flow: drainage density, roundness, the average gradient of the main channel, maximum elevation difference, bending coefficient of the main channel, the loose-material supply length ratio, vegetation area ratio, population density, and loose-material volume of unit area. The subjective weights of each indicator are obtained using the Analytic Hierarchy Process, while the objective weights are obtained using the CRITIC method. Based on this, the distance function is introduced to couple the subjective and objective weights, determine each indicator’s combined weights, and obtain the integrated evaluation score values of different debris flow hazards. Considering the integrated evaluation score of debris flow, cluster analysis was used to classify 14 debris flows and cluster effectiveness indicators were introduced to determine the effectiveness of debris flow classification. A quantitative standard for the risk of debris flow within the study area was proposed, and finally, a risk assessment of debris flow in the study area was made. Comparing the results of this paper with the gray correlation method, the coupled synergistic method, and the geological field survey results, proves that the proposed method is feasible and provides a reasonable scientific basis for the study of the hazard assessment of regional debris flow clusters and other related issues within the scope of the Jianjiang River basin and other areas.

Numerical simulation study on the spontaneous rupture process and its influencing factors of the 2001 MS 8.1 Kunlun earthquake in China

On November 14, 2001, the MS 8.1 Kunlun earthquake occurred in the west of Kunlun Mountain pass in the East Kunlun fault zone of the Qinghai-Tibet Plateau, China. The field investigation and the results of kinematic inversion indicate that it is a strike-slip earthquake with a complex rupture process. The study of the spontaneous rupture process of this earthquake and its influencing factors is of great significance for understanding the occurrence mechanism of continental large earthquakes. First, based on the results of geological survey and kinematic inversion, a three-dimensional non-planar fault model is established. Then, using the curved-grid finite difference method (CG-FDM), the dynamic rupture process of the 2001 MS 8.1 Kunlun earthquake is numerically reproduced by adjusting the parameters for numerical simulation experiments. On this basis, the influence of background stress field, fault geometry and friction coefficient on the surface slip distribution, seismic moment rate function and rupture velocity are discussed respectively. The results show that the important reasons for the super-long rupture scale and super-shear rupture velocity of this earthquake may be the clockwise rotation of the maximum horizontal principal compressive stress along the NNE ∼ NE direction and the low friction coefficient distribution on the whole fault surface. The difference between the dynamic and static friction coefficients along the fault strike may be non-uniform, and it may be larger on the main fault than that on the secondary fault. This will result in a higher level of stress drop on the main fault, leading to the occurrence of super-shear rupture and the slip distribution with the Kusai Lake as the macroseismic epicenter. The large local geometric variation along the strike of the main fault may also have some influence on the distribution of co-seismic slip and the location of the super-shear rupture. In addition, the numerical simulation results in this paper confirm the conclusion that the East Kunlun fault zone has low friction coefficient.

Construction Measures for Defect Reinforcement of Concrete Structures in Nanshan Water Purification Plant

The concrete material due to conveniently, price is low wait for a reason, is currently the mainstream architecture materials, concrete is subject to corrosion in the process of serving, however, especially in wastewater treatment, water purification and other service of concrete structures under complicated environment, especially the strength degradation, the service life of the structure and the structure of security is extremely unfavorable. In this paper, the structural defects of the primary sedimentation tank of a set of system in Shenzhen Nanshan Water purification Plant are detected, the geological survey results and related construction experience are analyzed, and the anti-seepage reinforcement construction measures are put forward.

ПРОСТРАНСТВЕННОЕ РАЗВИТИЕ УДМУРТИИ И ГЛАВНЫЕ ЗАДАЧИ ИНЖЕНЕРНОЙ ГЕОЛОГИИ

In the modern domestic economy, investment and construction activities are the driver of the development of the country as a whole and its individual regions. The growth in the pace of construction should be considered as an important factor in ensuring sustainable and balanced spatial development of the Russian Federation, allowing each subject of the Russian Federation to implement promising economic specializations, as well as participate in the implementation of large interregional investment projects. The purpose of the study is to identify the relationship between the spatial development of the Udmurt Republic and the solution of applied problems of engineering geology. The methodological basis of the study is the normative documents on the spatial development of the territories of the Russian Federation, the basic categories of management of investment and construction activities, as well as the results of geological surveys. The main research method is the analysis of empirical data on implemented construction projects of spatial development of the Udmurt Republic, the results of the program-target approach in the development of rural areas. It is shown that the results of engineering and geological surveys, which are one of the basic stages of construction work, allow us to determine the feasibility and feasibility of construction work, their technical validity in a particular area at the design stage. The authors of the article believe that the program-oriented approach to the spatial development of the country implemented in the Russian Federation requires solving applied problems of engineering geology for the conditions of the Udmurt Republic. The main tasks of engineering geology are related to the study of soils, geological processes, and the elucidation of the causes provoking certain geological processes, including the influence of neotectonics and modern geodynamics on the engineering-geological and hydrogeological conditions of the territory.

Consolidation of loose foundation soil for esplanade project in Kaliningrad

The article presents the practical experience of pre-construction compaction of loose water-saturated clay foundation soils during the construction of Paradnaya Embankment in Kaliningrad. The engineering and geological conditions of the embankment construction site were complicated by the occurrence of a significant thickness (up to 15 m) of highly compressible flowing silts from the surface. The base preparation was carried out by preliminary compaction of loose soils with the ballasting embankment using vertical geodrains. The geotechnical monitoring system at the site was implemented after the construction of the ballasting embankment, in connection with which the designers made a premature conclusion that 90% of the degree of consolidation of soft soils according to the readings of pore pressure sensors was reached only 2 months after the filling of the ballasting embankment. The authors of the article analyzed the calculation methods of the consolidation process used in the design and the results of geotechnical monitoring. A repeated prediction of deformations of the soil mass from its compaction by the ballasting embankment was performed by a numerical method, taking into account the nature of the transfer of the load to the foundation, as well as the presence of shore protection structures of the embankment. A non-standard method was used to assess the total settlement of the ballasting embankment and the degree of consolidation of the foundation in the absence of correct monitoring data, which consists in determining the top elevations of loose soils by drilling control observation wells and comparing them with the results of engineering and geological surveys performed before the start of construction.

Výsledky druhej fázy geologického prieskumu hlbokomorských polymetalických konkrécií v prieskumnom území Spoločnej organizácie Interoceanmetal

The exploration rights of the Interoceanmetal Joint Organization for exploration of polymetallic nodules (PMN) are granted from 29 March 2001 to an area located within the Clarion-Clipperton Zone (CCZ) in the eastern central Pacifi c Ocean. Exploration area covers 75,000 km2 and consists of two sectors (B1 and B2). The B2 sector comprises four exploration blocks (H11, H22, H33 and H44). The most prospective area, selected for detailed research, is marked as H22_NE exploitable block and delineated within the H22 exploration block. The article presents results of geological survey, based mostly on the data collected during the second phase of exploration in the licence area (2016–2021, extension of the contract). Results are based on IOM’s expeditions and relevant analytical work. During the IOM-2018 expedition high resolution bathymetric survey of H11, H22, H33 and H44 exploration blocks was carried out. The IOM-2019 expedition provided a new set of the data obtained using the distance methods (side-scan sonar, profi ler) and contact methods (box-corer and gravity corer) in H22_NE exploitable block, H33 exploration block and preliminary delineated Preservation Reference Zone. The study was focused on analytical work based on sediment and nodule analyses of samples in H22 exploration block and H22_NE exploitation block. New estimation of mineral resources in B2 sector was caried out using the geostatistical method of ordinary block kriging with Yamamoto correction. The polymetallic nodule resources have been classifi ed within the Inferred, Indicated and Measured Resources categories of the CRIRSCO classification system.

Research Results of the Earth Dam Condition of Cooling Pond of the Zaporizhzhia Nuclear Power Plant

Purpose. The work is aimed to determine the real location in space and conduct possible measurement of the true geometric dimensions of the NPP cooling pond dam, especially its underwater part and to detect the additional and previously unaccounted factors that could affect these parameters, as well as the state of the entire structure in general. Methodology. A comprehensive analysis of all available materials about engineering surveys and geotechnical studies was carried out at the dam of the cooling pond of the Zaporizhzhia NPP. Due to this, a more comprehensive look at the results of engineering and geological surveys was obtained. Findings. The state of soils in the body of the earth dam can be influenced by weakened and poorly studied zones of the dam. These zones were determined based on the analysis of the soil studies data of the dam’s ground. Previously uncovered issues on the operation of the facility were raised and considered. The ways and methods for additional study of the earth dam of the cooling pond were selected, the conditions for their use were substantiated. A numerical relationship between the thickness of loose soils and the amount of surface subsidence were determined for the first time. A generalized geological section of the dam body was compiled for further modeling of geotechnical processes. Originality. For the first time since construction, a comprehensive program was developed for assessing the technical condition of the cooling pond dam using innovative methods from the Laboratory of Research of Nuclear and Thermal Power Plants in Prydniprovska State Academy of Civil Engineering and Architecture (PSACEA). In particular, combined hydrographic-geodetic and aerovisual methods were proposed using specially designed universal leading signs that have no analogues in world practice. Practical value. The application of the developed comprehensive program using innovative methods allows assessing the technical condition of the cooling pond dam of the NPP.

Permian arc magmatism in southern Tibet: Implications for the subduction and accretion of the Zhikong–Sumdo Paleo-Tethys Ocean

The tectonic evolution of the Zhikong–Sumdo Paleo-Tethys Ocean (Hereafter referred to as Zhikong–Sumdo Ocean) in southern Tibet is controversial due to the limited records of arc magmas. Here, the newly discovered Zhangda complex in the Zhikong area of Tibet is selected as the research object. Zircon U–Pb geochronology, zircon Hf isotopes, whole-rock geochemistry and Sr-Nd isotope analyses performed based on field geological surveys show that the Zhangda complex is composed of Early Permian hornblende gabbro (278.3 ± 1.1 Ma), cumulate gabbro (277.4 ± 1.7 Ma), tonalite dike (281.1 ± 1.9 Ma), Middle–Late Permian gabbro diorite (267.8 ± 2.9 Ma, 269.0 ± 3.1 Ma), and tonalite (258.0 ± 2.7 Ma). The Zhangda mafic rocks show weak fractionation of light and heavy rare earth elements, and they are enriched in large ion lithophile elements and depleted in high field strength elements. Meanwhile, the Zhangda tonalites show the characteristics of metaluminous calc-alkaline I-type granite. They are enriched in light rare earth and large ion lithophile elements and are depleted in heavy rare earth and high field strength elements. The ɛHf(t), ɛNd(t) and the initial 87Sr/86Sr values of the mafic rocks are + 9.3–+14.4, +4.2–+5.9 and 0.702803–0.704264, respectively, while the ɛHf(t), ɛNd(t) and initial 87Sr/86Sr values of the tonalites are + 9.8–+16.3, +5.5–+6.1 and 0.703105–0.704071, respectively. Combined with the regional geological survey results, the Permian Zhangda complex was found to be formed in a tectonic setting of subduction north of the Zhikong–Sumdo Ocean. The Zhangda mafic rocks were formed by partial melting of the depleted mantle modified by subducted metasomatic fluids, while the Zhangda tonalites were the products of partial melting of the juvenile crust. During the Zhikong–Sumdo Ocean subduction, mantle-derived magma underplating led to the growth of juvenile crust in southern Tibet.

Age and origin of tuffites from the Hekou Formation in the Napo basin, Southwest Guangxi and its tectonic implications

桂西南那坡盆地位于八布-Song Hien构造带，发育早-中三叠世岩浆岩和巨厚海相碎屑岩系，是研究华南地块南缘古特提斯造山过程的关键地区。本文对那坡盆地中三叠统河口组中-上部的两套沉凝灰岩开展了详细的岩石学、地球化学和锆石U-Pb-Hf同位素分析研究。两件沉凝灰岩样品LA-ICP-MS锆石U-Pb定年结果分别为240.6±1.0Ma和236.3±0.8Ma，指示河口组碎屑岩沉积时代为中三叠世拉丁期，部分为晚三叠世卡尼期早期。全岩地球化学结果显示，该沉凝灰岩属于亚碱性英安质，富集轻稀土（LREEs）和大离子亲石元素（LILEs）、Rb、Th和U，亏损高场强元素（HFSEs），具有显著的Nb、Ta和Ti负异常。沉凝灰岩锆石具有较低的ε_Hf（t）值（-18.6~-6.3）和较老的地壳模式年龄（t_DM^C=1664~2434Ma），结合锆石微量元素特征认为其形成于俯冲环境。整体上，那坡盆地河口组沉凝灰岩表现出俯冲作用形成的岛弧火山岩地球化学特征，推断其来源于桂西南凭祥地区的中-晚三叠世酸性火山岩。结合已有区域地质调查成果，认为华南地块南缘八布-Cao Bang古特提斯分支洋盆于晚二叠世至晚三叠世早期向北俯冲，随后自西向东呈剪刀式逐渐闭合。华南地块与北越地块完全碰撞拼合的时间发生在晚三叠世中晚期。;The Napo basin, Southwest Guangxi, locates in the Babu-Song Hien tectonic belt and shows widespread Early-Middle Triassic magmatic and massive marine clastic rocks, which plays a key role in studying the evolution of the Paleo-Tethys orogeny along the southern margin of South China block. In this paper, we have carefully analyzed the petrology, geochemistry and zircon U-Pb-Hf isotope for two sets of tuffites in the middle-upper part of the Middle Triassic Hekou Formation, Napo basin. LA-ICP-MS zircon U-Pb dating results of the two tuffite samples yield the ages at 240.6±1.0Ma and 236.3±0.8Ma, respectively, indicating that the clastic rocks of Hekou Formation should be deposited during the Middle Triassic Ladinian stage, some of which may extend to the early Carnian of Late Triassic. Whole-rock geochemical results indicate that the tuffites are subalkaline dacitic, enriched in light rare earth elements (LREEs), large ion lithophile elements (LILEs), Rb, Th and U, depleted in high field strength elements (HFSEs), and have significant negative anomalies of Nb, Ta and Ti. The tuffite zircons have lower ε_Hf(t) values (-18.6~-6.3) and older crustal model ages (t_DM^C=1664~2434Ma). Combined with trace elements, we suggest these zircons may have been formed in subduction-related setting. In summary, the tuffite samples from the Hekou Formation in Napo basin display the geochemical characteristics of island-arc volcanic rock, which are inferred to be derived from the Middle-Late Triassic acidic volcanic rocks in Pingxiang area, Southwest Guangxi. Given the existing geological survey results, it is concluded that the Babu-Cao Bang Paleo-Tethys branch ocean along the southern margin of the South China block should subduct northward during the Late Permian-early Late Triassic, and subsequently closed with scissor-style from west to east. The collision between the South China block and North Vietnam terrane should occur in the middle to late stage of Late Triassic.

Compound Karst Cave Treatment and Waterproofing Strategy for EPB Shield Tunnelling in Karst Areas: A Case Study

There is high risk of water inrush and ground collapse accidents when tunnelling in karst areas. Based on the case study of an urban metro tunnel, this paper focuses on karst cave treatment and waterproofing strategies for earth pressure balancing (EPB) shield tunnelling in karst areas containing large amounts of karst caves and fissures. When the shield machine enters the karst area, water gush easily occurs, posing serious threats to tunnelling safety. The distribution characteristic of limestone fractures, karst caves, and fissures in the karst area were analyzed according to the geological survey results. Further, water inrush risk and engineering difficulties were analyzed. Subsequently, a compound karst cave treatment and waterproofing strategy for EPB shield tunnelling was proposed and implemented. Water inflow is successfully reduced and ground collapse accident is avoided using the compound karst cave treatment and waterproofing strategy.

Application of Statistical Prediction Model to the Reservoir Induced Seismic Risk Analysis of Aqing Hydropower Station in Xizang

Based on field seismic geological survey and previous research results, this paper analyzed tectonic background, seismicity and hydrogeological conditions of Aqing hydropower station in Xizang respectively, then calculated the probability of reservoir induced seismicity. The results showed that it is possible for the reservoir induced seismicity occurring, whose probability is 0.455. In detail, the probabilities of occurring moderate-strong, weak, and micro earthquake are 0.089, 0.070, and 0.296 respectively. Under these circumstances and based on the intensity attenuation relationship of reservoir induced seismicity, it can be deduced that the moderate-strong earthquake would occur with epicentral intensity VII, and the lengths of major axis and minor axis are 6.5 km and 3.3 km respectively.

Influence of the deep pit construction on a settlements of surrounding buildings

Various methods exist for calculating the subgrade settlements of foundations built on soil subgrade without defects and damages. The physical and mechanical characteristics of such soil subgrade are usually determined using the results of engineering and geological surveys and other methods that characterize their in-situ conditions before construction. It is usually assumed that these characteristics are constant throughout their life cycle regardless whether they get later disturbed by buildings and/or structures. In fact, the mechanical characteristics of the soils of the subgrade vary and are subject of continuous changes due to various factors. Therefore, the use of existing calculation methods often lead to inadequate estimates of settlements of subgrade and foundations of buildings and structures. Assessment of vertical deformations of soil subgrade in the zone of influence of deep pits usually falls in this category. The method for calculating the settlement of bases and foundations of buildings was developed taking into account the formation and development of defects and damages in the soil structure in the zone of influence of a deep pit. It is based on a method of layer-by-layer summation, taking into account the spatial stress state of the soil mass and changes in the mechanical state of the soil due to surcharge conditions.

Method and Realization of Efficient Extraction of Basic Geological Data from Two-Dimensional Mine Drawings

In coal mining technology systems, it is very important to acquire, store, and represent basic geological data comprehensively and accurately. Based on the current working mode and information level in mining geology at coal mines, this paper proposes a process of building basic geological database for modeling of coal mines by using existing results’ data of mining geology and develops the efficient program for getting the basic geological data from the important 2D plane drawings’ achievement at mines, such as the contour maps of mine coal seam floors, geological cross-sections, underground drilling results, and geological survey results, based on AutoLISP, which is a programming language for the secondary development of AutoCAD. The obtained data in general text format is stored and managed by the MongoDB database, which realizes the storage, query, analysis, and correction of massive data of geological objects in the space of the underground coalmine. The application results show that compared with the previous data acquisition methods such as manual input and graphic transformation attribute, the extraction of spatial and attribute data from the existing mine 2D plane drawings by programming can effectively avoid the prominent problems such as artificial gross error, distortion of graph conversion, and different database structure, make the obtained spatial geological data more comprehensive, accurate, and effective, and, meanwhile, increase the rate by more than 60%, which plays an important role in data support for the construction of the geological modeling systems for transparent mines.