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Investigation of the first quasi-rectangular metro tunnel constructed by the 0-θ method

Frontiers of Structural and Civil Engineering 2023年第11期17卷 1707-1722页

作者： Peinan LI Xue LIU Xi JIANG Xuehui ZHANG Jun WU Peixin CHEN College of Environmental Science and Engineering Donghua UniversityShanghai 201620China Department of Civil and Environmental Engineering University of TennesseeKnoxvilleTN 37996USA Department of geoscience and Engineering Delft University of TechnologyDelft 2628The Netherlands College of Urban Railway Transportation Shanghai University of Engineering ScienceShanghai 201620China Shanghai Tunnel Engineering Co..ltd. Shanghai 200032China

Quasi-rectangular shield tunneling is a cutting-edge trenchless method for constructing metro tunnels with double tubes,owing to its advantages in saving underground space and reducing ground ***,the conventional quasi-rectangular shield tunneling method is not applicable when constructing a tunnel without a center pillar,such as a scissor crossover section of a metro ***,the O-0 tunneling method,which combines the quasirectangular shield and pipe jacking methods,was investigated in this study to solve the aforementioned construction *** study presents a case study of the Sijiqing Station of the Hangzhou Metro Line 9 in China,in which the O-0 method was first proposed and *** techniques such as switching between two types of tunneling modes and the tunneling process control in complex construction environments were *** results demonstrated that the O-0 method can address the technical challenges presented by the post-transition line with a high curvature and a scissors crossover *** addition,the adoption of the 0-0 method ensured that the transformation between shield tunneling and pipe jacking was safe and *** ground settlement monitoring results demonstrated that the disturbance to the surrounding environment can be limited to a safe *** case study contributes to the construction technology for a metro tunnel containing both post-transition lines with a small turning radius and a scissors crossover line.A practical construction experience and theoretical guidance were provided in this study,which are of significance for both the industry and academia.

关键词： quasi-rectangular tunnel O-0 method pipe jacking shield tunneling underground space

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Geochronological and genetic characterization of basaltic basement from western offshore basins in India

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geoscience Frontiers 2024年第5期15卷 372-398页

作者： Piyush Gupta Shakti Singh Rathore Sandeep Singh Geochronology Laboratory KDMIPEOil and Natural Gas Corporation Ltd.9Kaulagarh RoadDehradun 248195India Department of Earth Sciences Indian Institute of TechnologyRoorkee 247667India

^(40)Ar-^(39)Ar geochronology,geochemistry,and Sr-Nd isotopic compositions of 30 core samples from 24 offshore drill wells in the Western offshore basins have been used to characterize the genetics of the volcanic basement from the Kutch,Mumbai,and Kerala-Konkan offshore *** from the volcanic basement rocks demonstrate extremely varied isotopic and geochemical fingerprints,which are suggestive of significantly diverse parent magma compositions and emplacement *** tholeiitic basement from Kutch Offshore basin has Ar-Ar ages that range between 60 Ma and 62 *** basement is characterised by a within-plate basalt signature,with depleted isotopic signatures similar to least contaminated Deccan Traps basalts,and a component of subducted crustal *** basement from Mumbai Offshore Basin has eruption ages between 63 Ma and 65 Ma and show a strong within-plate OIB *** and isotopic signatures are consistent with Renuion lavas and an enriched-end member of Deccan Traps ***,Kerala-Konkan Offshore Basin shows significant E-MORB affinity and is characterized by primitive-mantle signatures and least contamination from the upper continental crust,with ages of eruption between 60 Ma and 61 Ma based on obtained^(40)Ar-^(39)Ar *** study suggests that the Mumbai Offshore Basalts’mode of the eruption was comparable with onshore Deccan volcanism,whereas the basaltic basement in Kutch Offshore was formed after the main phase of Deccan eruption and may have been an offshoot of a"tail"of the main Deccan *** parent magma for the volcanic E-MORB basement in the Kerala-Konkan Offshore Basin is thought to have come from mixing along the Carlsberg Mid-Oceanic Ridge and the material from the Réunion plume with the northward movement of the Indian Plate during the Early *** is thought to have occurred concurrently with the formation of the Chagos-Laccadive Ridge.

关键词： ^(40)Ar-^(39)Ar geochronology Western offshore basins Kutch offshore basin Mumbai offshore basin Kerala-Konkan offshore basin

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Logging evaluation of deep multi-type unconventional gas reservoirs in the Songliao basin,northeast China:Implications from continental scientific drilling

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geoscience Frontiers 2022年第6期13卷 122-137页

作者： Shuangbiao Han Chaohan Xiang Xin Du Linfeng Xie Songtao Bai Chengshan Wang College of geoscience and Surveying Engineering China University of Mining and TechnologyBeijing 100083China State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing 102249China China Petroleum Logging Co.ltd Xi’an 710077China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesBeijing 100083China

Multi-type unconventional gas-bearing reservoirs with different lithologies and gas accumulation potential occur in the deep part of the Songliao ***,the reservoirs are non-homogeneous,the gas components differ substantially,and not all types of gas-bearing reservoirs have been identified or *** International Continental Scientific Drilling Program(ICDP)is used as an example to conduct qualitative and quantitative evaluations of deep multi-type unconventional gas-bearing reservoirs using conventional and specialized logging *** core test data are used to determine the physical *** porosity and permeability are compared and analyzed using different methods and *** results show that the reservoirs have low to ultra-low porosity and ultra-low *** on the comparison of the rock mechanical parameters and mineral composition,brittleness evaluation parameters are proposed for different types of deep reservoirs in the study *** mineral brittleness index is highly consistent with the brittleness index based on rock *** identification method for deep multi-type gas-bearing reservoir and a classification approach for different gas properties are established based on the logging response and parameter *** methane gas reservoirs have low density(DEN)and low compensated neutron logging(CNL)values and high acoustic(AC)time difference and high resistivity(RT)*** CO_(2)gas reservoirs have lower RT values and higher CNL values than the hydrocarbon gas *** comprehensive analysis of deep gas source rock conditions and of the source-reservoir relationship provides insights for the evaluation of deep multi-type unconventional gas *** discovery of high hydrogen content is of significant importance for developing new areas for deep natural gas exploration.

关键词： Logging response Reservoir characteristics Comprehensive evaluation Exploration direction Songliao basin

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Classification random forest with exact conditioning for spatial prediction of categorical variables

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Artificial Intelligence in geosciences 2021年第1期2卷 82-95页

作者： Francky Fouedjio AngloGold Ashanti Australia ltd. Growth and Exploration140 St.Georges TerracePerthWA6000Australia

Machine learning methods are increasingly used for spatially predicting a categorical target variable when spatially exhaustive predictor variables are available within the study *** though these methods exhibit competitive spatial prediction performance,they do not exactly honor the categorical target variable's observed values at sampling locations by *** the other side,competitor geostatistical methods perfectly match the categorical target variable's observed values at sampling locations by *** many geoscience applications,it is often desirable to perfectly match the observed values of the categorical target variable at sampling locations,especially when the categorical target variable's measurements can be reasonably considered *** paper addresses the problem of exact conditioning of machine learning methods for the spatial prediction of categorical *** introduces a classification random forest-based approach in which the categorical target variable is exactly conditioned to the data,thus having the exact conditioning property like competitor geostatistical *** proposed method extends a previous work dedicated to continuous target variables by using an implicit representation of the categorical target *** basic idea consists of transforming the ensemble of classification tree predictors'(categorical)resulting from the traditional classification random forest into an ensemble of signed distances(continuous)associated with each category of the categorical target ***,an orthogonal representation of the ensemble of signed distances is created through the principal component analysis,thus allowing to reformulate the exact conditioning problem as a system of linear inequalities on principal component ***,the sampling of new principal component scores ensuring the data's exact conditioning is performed via randomized quadratic *** resulting conditional signed distances are t

关键词： Categorical variable Classification Exact conditioning Principal component analysis Signed distance Spatial prediction Quadratic programming

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Vertical variation of trace elements and its relation to the water-bearing capacity of Ordovician strata,in Datun coal field

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Mining Science and Technology 2009年第2期19卷 166-169页

作者： LIU Huai-zhong HAN Bao-ping School of Resources and geoscience China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China School of Environmental Science and Spatial lnformatics China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China

We tested for fourteen trace elements in samples collected from the Ordovician strata in Datun coal field. The vertical concentration variation of these trace dements is reported. The relationship of the variation to the water-bearing capacity of the Ordovician strata is discussed. The minimum concentration of eleven （of 14 total） trace elements appears in the lower Majiagou formation. The maximum concentrations mainly appear in the Badou and Jiawang formations： eight maxima are located in Badou and four more are in Jiawang. The study of karst development and the water-bearing capacity of Ordovician strata shows that karst is well developed in the Majiagou formation and there is a consequent high water-bearing capacity in this formation： Badou and Jiawang formations are contrary to this situation. The results illustrate that the minimum concentrations of most trace elements within certain Ordovician formations can be taken as strong evidence for the existence of a well developed karst and a high water-bearing capacity.

关键词： Ordovician trace element water-bearing capacity Damn coal field

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Exact Conditioning of Regression Random Forest for Spatial Prediction

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Artificial Intelligence in geosciences 2020年第1期1卷 11-23页

作者： Francky Fouedjio AngloGold Ashanti Australia ltd. Growth and Exploration140 St.Georges TerracePerthWA6000Australia

Regression random forest is becoming a widely-used machine learning technique for spatial prediction that shows competitive prediction performance in various geoscience *** other popular machine learning methods for spatial prediction,regression random forest does not exactly honor the response variable’s measured values at sampled ***,competitor methods such as regression-kriging perfectly fit the response variable’s observed values at sampled locations by *** matching the response variable’s measured values at sampled locations is often desirable in many geoscience *** paper presents a new approach ensuring that regression random forest perfectly matches the response variable’s observed values at sampled *** main idea consists of using the principal component analysis to create an orthogonal representation of the ensemble of regression tree predictors resulting from the traditional regression random ***,the exact conditioning problem is reformulated as a Bayes-linear-Gauss problem on principal component *** problem has an analytical solution making it easy to perform Monte Carlo sampling of new principal component scores and then reconstruct regression tree predictors that perfectly match the response variable’s observed values at sampled *** reconstructed regression tree predictors’average also precisely matches the response variable’s measured values at sampled locations by *** proposed method’s effectiveness is illustrated on the one hand using a synthetic dataset where the ground-truth is available everywhere within the study region,and on the other hand,using a real dataset comprising southwest England’s geochemical concentration *** is compared with the regression-kriging and the traditional regression random *** appears that the proposed method can perfectly fit the response variable’s measured values at sampled locations while achieving good out

关键词： Exact conditioning Monte Carlo sampling Multi-Gaussian Spatial prediction Principal component analysis Random forest

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A Method for Calculating Oil Field Relative Permeability Curve by Using Water Drive Characteristic Curve in High Water Cut Stage

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Journal of geoscience and Environment Protection 2022年第2期10卷 47-54页

作者： Juan Du CNOOC ltd.-Tianjin Tianjin China

With the production of strong bottom water reservoir, it will soon enter the ultra-high water cut stage. After entering the ultra-high water cut period, the main means of stable production is liquid extraction. Large liquid volume has a certain impact on the physical property distribution and fluid seepage law of the oilfield. The relative permeability curve measured according to the industry standard is not used for the prediction of development indicators and the understanding of the dynamic law of the oilfield. In order to understand the characteristics of water drive law in high water cut stage of water drive oilfield, starting from the water drive characteristic curve in high water cut stage, the method for calculating the relative permeability curve is deduced. Through numerical simulation verification and fitting the actual production data, it is confirmed that the obtained relative permeability curve is in line with the reality of the oilfield, It can provide some guiding significance for understanding the production law and water drive law of strong bottom water reservoir in ultra-high water cut stage.

关键词： Strong Bottom Water Reservoir High Water Cut Stage Water Drive Curve Relative Permeability Curve

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Microseismic monitoring and forecasting of dynamic disasters in underground hydropower projects in southwest China:A review

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第8期15卷 2158-2177页

作者： Biao Li Nuwen Xu Peiwei Xiao Yong Xia Xiang Zhou Gongkai Gu Xingguo Yang School of geoscience and Technology Southwest Petroleum UniversityChengdu610500China State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resource and HydropowerSichuan UniversityChengdu610065China Power China Chengdu Engineering Co. LtdChengdu610072China Chn Energy Dadu River Hydropower Development Co. LtdChengdu610041China China Three Gorges Construction Engineering Corporation Chengdu610095China

The underground hydropower projects in Southwest China is characterized by large excavation sizes,high geostresses,complicated geological conditions and multiple construction *** disasters such as collapses,large deformations,rockbursts are frequently encountered,resulting in serious casualties and huge economic *** review mainly presents some representative results on microseismic(MS)monitoring and forecasting for disasters in hydropower underground ***,a set of new denoising,spectral analysis,and location methods were developed for better identification and location of MS ***,the tempo-spatial characteristics of MS events were analyzed to understand the relationship between field construction and damages of surrounding *** with field construction,geological data,numerical simulation and parametric analysis of MS sources,the focal mechanism of MS events was revealed.A damage constitutive model considering MS fracturing size was put forward and feedback analysis considering the MS damage of underground surrounding rocks was ***,an MS multi-parameter based risk assessment and early warning method for dynamic disasters were *** technology for control of the damage and deformation of underground surrounding rocks was proposed for underground ***,two typical underground powerhouses were selected as case *** achievements can provide significant references for prevention and control of dynamic disasters for underground engineering with similar complicated geological conditions.

关键词： MS monitoring Forecasting method Control technology Dynamic disaster Underground engineering

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Exploring mechanism of hidden,steep obliquely inclined bedding landslides using a 3DEC model:A case study of the Shanyang landslide in Shaanxi Province,China

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China Geology 2024年第2期7卷 303-314,I0001-I0003页

作者： Jia-yun Wang Zi-long Wu Xiao-ya Shi Long-wei Yang Rui-ping Liu Na Lu Xi’an Center of China Geological Survey/Northwest China Center for geoscience Innovation Xi’an 710119China Xi’an University of Science and Technology Xi’an 710054China Wuhan Design&Research Institute Co. Ltd.of China Coal Technology&Engineering GroupWuhan 430064China

Catastrophic geological disasters frequently occur on slopes with obliquely inclined bedding structures(also referred to as obliquely inclined bedding slopes),where the apparent dip sliding is not readily *** phenomenon has become a focal point in landslide ***,there is a lack of studies on the failure modes and mechanisms of hidden,steep obliquely inclined bedding *** study investigated the Shanyang landslide in Shaanxi Province,*** field investigations,laboratory tests of geotechnical parameters,and the 3DEC software,this study developed a numerical model of the landslide to analyze the failure process of such *** findings indicate that the Shanyang landslide primarily crept along a weak interlayer under the action of *** landslide,initially following a dip angle with the support of a stable inclined rock mass,shifted direction under the influence of argillization in the weak interlayer,moving towards the apparent dip *** slide resistance effect of the karstic dissolution zone was increasingly significant during this process,with lateral friction being the primary resistance force.A reduction in the lateral friction due to karstic dissolution made the apparent dip sliding characteristics of the Shanyang landslide more ***,deformations such as bending and uplift at the slope’s foot suggest that the main slide resistance shifts from lateral friction within the karstic dissolution zone to the slope foot’s resistance force,leading to the eventual buckling failure of the *** study unveils a novel failure mode of apparent dip creep-buckling in the Shanyang landslide,highlighting the critical role of lateral friction from the karstic dissolution zone in its failure *** insights offer a valuable reference for mitigating risks and preventing disasters related to obliquely inclined bedding landslides.

关键词： Landslide Steep obliquely inclined bedding slope Failure mode Failure mechanism Apparent dip creep-buckling Lateral friction 3DEC model Landslide numerical model Geological hazards survey engineering

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Characterization of Complex Fracture System in Volume Fracturing of Shale Gas Reservoir

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Journal of geoscience and Environment Protection 2023年第7期11卷 1-10页

作者： Songru Mou Jie Tan Wengtong Zhang Zhengyang Tan Zijin Li Tianjin Branch of CNOOC ltd. Tianjin China

After volume fracturing of horizontal wells in shale gas reservoir, an extremely complex fracture system is formed. The space area of the fracture system is the reservoir reconstruction volume of shale gas reservoir. The geometric parameters such as crack length, crack width, crack height, and characteristic parameters such as crack permeability and fracture conductivity proposed for a single crack in conventional fracturing are insufficient to describe and characterize the complex network fracture system after volume fracturing. In this paper, the discrete fracture modeling method is used to establish the volume fracturing network fracture model of horizontal wells in shale gas reservoir by using the random modeling method within the determined reservoir space. The model is random and selective, and can fully provide different forms of volume fracturing fracture expansion, such as conventional fracture morphology, line network model and arbitrarily distributed network fractures. The research results provide a theoretical basis for the development plan and stimulation plan of shale gas reservoir, and have important reference value and significance for other unconventional gas reservoir fracturing.

关键词： Reservoir Reconstruction Volume Graphical Combination Method Boundary Analysis Method Probability Method Network Fracture Density

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