The Yangtze Three Gorges Project (TGP) is the key backbone project to develop and harness the Yangtze river in China. As the largest water conservancy project in the world with the earth and rock excavation amounting ...The Yangtze Three Gorges Project (TGP) is the key backbone project to develop and harness the Yangtze river in China. As the largest water conservancy project in the world with the earth and rock excavation amounting up to 102.83×10 6 m 3, it is, therefore, the largest project on a scale of geomechanical engineering. The involvement of numerous domestic and foreign research institutes in the scientific research has promoted the development of geomechanics. Some rock and soil mechanical issues arising during construction of the Three Gorges Project are discussed in this article.展开更多
Knowledge of the mechanical behavior of planetary rocks is indispensable for space explorations.The scarcity of pristine samples and the irregular shapes of planetary meteorites make it difficult to obtain representat...Knowledge of the mechanical behavior of planetary rocks is indispensable for space explorations.The scarcity of pristine samples and the irregular shapes of planetary meteorites make it difficult to obtain representative samples for conventional macroscale rock mechanics experiments(macro-RMEs).This critical review discusses recent advances in microscale RMEs(micro-RMEs)techniques and the upscaling methods for extracting mechanical parameters.Methods of mineralogical and microstructural analyses,along with non-destructive mechanical techniques,have provided new opportunities for studying planetary rocks with unprecedented precision and capabilities.First,we summarize several mainstream methods for obtaining the mineralogy and microstructure of planetary rocks.Then,nondestructive micromechanical testing methods,nanoindentation and atomic force microscopy(AFM),are detailed reviewed,illustrating the principles,advantages,influencing factors,and available testing results from literature.Subsequently,several feasible upscaling methods that bridge the micro-measurements of meteorite pieces to the strength of the intact body are introduced.Finally,the potential applications of planetary rock mechanics research to guiding the design and execution of space missions are environed,ranging from sample return missions and planetary defense to extraterrestrial construction.These discussions are expected to broaden the understanding of the microscale mechanical properties of planetary rocks and their significant role in deep space exploration.展开更多
Soil-rock mixtures containing macropore(SRMCM)is a kind of geological material with special mechanical properties.Located in the project area of Lenggu hydropower station on the Yalong River,Sichuan Province,China,the...Soil-rock mixtures containing macropore(SRMCM)is a kind of geological material with special mechanical properties.Located in the project area of Lenggu hydropower station on the Yalong River,Sichuan Province,China,there is an extremely unstable Mahe talus slide with a total volume of nearly160 million cubic meters,which is mainly composed of SRMCM.The study on the mechanical properties of SRMCM is of great significance for the engineering construction and safe operation.In this paper,laboratory tests and discrete element numerical tests based on three-dimensional scanning technology were conducted to study the influence of stone content,stone size,and the angle of the macropore structure on shear characteristics of SRMCM.The failure mechanism of SRMCM was discussed from a microscopic perspective.This work explains the internal mechanism of the influence of stone content,stone size,and the angle of the macropore structure on the strength of SRMCM through the microscopic level of stone rotation,force chain distribution,and crack propagation.As the macropore structure that intersects with the preset shear plane at a large angle could act as a skeleton-like support to resist the shear force,the fracture of the weak cemented surface of soil and stone in the macropore structure is an important cause of SRMCM destruction.展开更多
With few available soil organic carbon(SOC)profiles and the heterogeneity of those that do exist, the estimation of SOC pools in karst areas is highly uncertain.Based on the spatial heterogeneity of SOC content of 23,...With few available soil organic carbon(SOC)profiles and the heterogeneity of those that do exist, the estimation of SOC pools in karst areas is highly uncertain.Based on the spatial heterogeneity of SOC content of 23,536 samples in a karst watershed, a modified estimation method was determined for SOC storage that exclusively applies to karst areas. The method is a "soil-type method" based on revised calculation indexes for SOC storage. In the present study, the organic carbon contents of different soil types varied greatly, but generally decreased with increasing soil depth. The organic carbon content decreased nearly linearly to a depth of 0–50 cm and then varied at depths of 50–100 cm. Because of the large spatial variability in the karst area, we were able to determine that influences of the different indexes on the estimation of SOC storage decreased as follows: soil thickness > boulder content > rock fragment content > SOC content > bulk density. Using the modified formula, the SOC content in the Houzhai watershed in Puding was estimated to range from 3.53 to 5.44 kg m^(-2), with an average value of 1.24 kg m^(-2) to a depth of 20 cm, and from 4.44 to 14.50 kg m^(-2), with an average value of 12.12 kg m^(-2) to a depth of 100 cm. The total SOC content was estimated at 5.39*10^(5) t.展开更多
A self-developed elasto-plastic finite element program was used to analyze the construction sequence of high rock slope's stabilization in a coal-coking plant, and the result was compared with that employing the u...A self-developed elasto-plastic finite element program was used to analyze the construction sequence of high rock slope's stabilization in a coal-coking plant, and the result was compared with that employing the ultimate equilibrium method. Based on the results of finite element analysis, the stress contour graphs and displacement vector graphs at different construction steps were obtained, and the behavior of the slope during stabilization construction process was analyzed quantitatively. Based on the analysis of safety factors of three different schemes of stabilization and two different construction schemes, the assessment of stability and bracing design of the construction process were performed. The results show that the original reinforcement design is improper; the stability of the rock slope is controlled by a developed structural plane, the stability factor after excavation is less than 1, and the free surface should be braced in time; for stability, the construction sequence should adopt that bracing follows excavation step by step up to down; the local slide occurred during the construction process agrees with the dangerous slide determined by the numerical analysis, which proves the validity and rationality of the adopted method.展开更多
By combing the characteristics of drilling in Antarctic region, performance requirements on drilling fluid for Antarctic low temperature conditions, and research progress of low temperature drilling fluid, current pro...By combing the characteristics of drilling in Antarctic region, performance requirements on drilling fluid for Antarctic low temperature conditions, and research progress of low temperature drilling fluid, current problems of the drilling fluid have been sorted out, and the development direction of the drilling fluid has been pointed out. Drilling in the Antarctic region mainly includes drilling in snow, ice and subglacial rock formations, and drilling in Antarctic low temperature conditions will face problems in four aspects:(1) low temperature and large temperature changes in the drilling area;(2) likely well leakage and drillstring-sticking in the snow layer, creep in the ice layer, ice chip gathering jamming in the warm ice layer, well wall collapse in the subglacial rock formations;(3) lack of infrastructure and difficulty in logistical support;(4) fragile environment and low carrying capacity. After years of development, progresses have been made on low-temperature drilling fluids for the Antarctic region. Low-temperature petroleum-based drilling fluid, ethanol/ethylene glycol-based drilling fluid, ester-based drilling fluid and silicone oil-based drilling fluid have been developed. However, these drilling fluids have problems such as insufficient low-temperature tolerance, low environmental performance and weak wellbore stability, etc. In order to meet the performance requirements of drilling fluid under low-temperature conditions in Antarctic region, the working mechanisms of low-temperature drilling fluid must be examined in depth;environment-friendly low-temperature base fluid of drilling fluid and related additives must be developed to prepare environmentally friendly low temperature drilling fluid systems;multi-functional integrated adjustment method for drilling fluid must be worked out to ensure well wall stability and improve cutting-carry capacity when drilling ice formations and ice-rock interlayers;and on-site support operation codes must be established to provide technical support for Antarctic drilling.展开更多
The analysis of building structure in contact with soil involves an interactive process of stresses and strains developed within the structure and the soil field. The response of Piled-Raft Foundation system to the st...The analysis of building structure in contact with soil involves an interactive process of stresses and strains developed within the structure and the soil field. The response of Piled-Raft Foundation system to the structure is very challenging because there is an important interplay between the component of building structure and the soil field. Herein, soil-foundation-structure interaction of buildings founded on Piled-Raft Foundation is evaluated through 3D-Nonlinear Finite Element Analyses using PLAXIS3D FOUNDATION code. The soil settlements and forces demand of the high-rise building structures and foundation is computed. The parametric study affecting the soil-foundation-structure response has been carried out. The parameters such as construction phasing, sequential loading, building aspect ratios, soil failure models and thickness proportion of soil field stiff layer, are considered. It is concluded that the interaction of building foundation-soil field and super-structure has remarkable effect on the structure.展开更多
【目的】为了深入了解月面建造过程中月壤的力学特性,评估月基装备性能,优化月面建造作业,开展离散元法(discrete element method,DEM)在月壤接触力学领域的应用调查研究,旨在利用离散元法为未来月球基地建设提供理论指导和技术支持。...【目的】为了深入了解月面建造过程中月壤的力学特性,评估月基装备性能,优化月面建造作业,开展离散元法(discrete element method,DEM)在月壤接触力学领域的应用调查研究,旨在利用离散元法为未来月球基地建设提供理论指导和技术支持。【研究现状】基于地质勘探、资源采集及运输、建造作业等月面原位建造任务场景,分析月壤颗粒的建模与参数标定,介绍月基装备与月壤的接触作用研究现状,概述离散元法在钻-壤作用模拟、铲-壤作用模拟、轮-壤作用模拟及足-壤作用模拟中的应用,探讨基于离散元法的天然月基承载力分析。【结论与展望】提出降低几何模型复杂度、优化粒间接触模型及参数是提高宏观尺度月壤离散元建模精度以应对大规模月面建造场景的有效方法。认为利用离散元法进行铲挖式月壤采集装置及足式月球车设计在未来可以为月面建造提供可靠的技术支持。面向月面建造,离散元法将在水冰资源利用、建筑物月面承载力分析等方面提供科学依据。展开更多
文摘The Yangtze Three Gorges Project (TGP) is the key backbone project to develop and harness the Yangtze river in China. As the largest water conservancy project in the world with the earth and rock excavation amounting up to 102.83×10 6 m 3, it is, therefore, the largest project on a scale of geomechanical engineering. The involvement of numerous domestic and foreign research institutes in the scientific research has promoted the development of geomechanics. Some rock and soil mechanical issues arising during construction of the Three Gorges Project are discussed in this article.
基金supported by China Postdoctoral Science Foundation(No.2023TQ0247)Shenzhen Science and Technology Program(No.JCYJ20220530140602005)+2 种基金the Fundamental Research Funds for the Central Universities(No.2042023kfyq03)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515111071)the Postdoctoral Fellowship Program(Grade B)of China Postdoctoral Science Foundation(No.GZB20230544).
文摘Knowledge of the mechanical behavior of planetary rocks is indispensable for space explorations.The scarcity of pristine samples and the irregular shapes of planetary meteorites make it difficult to obtain representative samples for conventional macroscale rock mechanics experiments(macro-RMEs).This critical review discusses recent advances in microscale RMEs(micro-RMEs)techniques and the upscaling methods for extracting mechanical parameters.Methods of mineralogical and microstructural analyses,along with non-destructive mechanical techniques,have provided new opportunities for studying planetary rocks with unprecedented precision and capabilities.First,we summarize several mainstream methods for obtaining the mineralogy and microstructure of planetary rocks.Then,nondestructive micromechanical testing methods,nanoindentation and atomic force microscopy(AFM),are detailed reviewed,illustrating the principles,advantages,influencing factors,and available testing results from literature.Subsequently,several feasible upscaling methods that bridge the micro-measurements of meteorite pieces to the strength of the intact body are introduced.Finally,the potential applications of planetary rock mechanics research to guiding the design and execution of space missions are environed,ranging from sample return missions and planetary defense to extraterrestrial construction.These discussions are expected to broaden the understanding of the microscale mechanical properties of planetary rocks and their significant role in deep space exploration.
基金funded by the National Natural Science Foundation of China(Grant No.41672258)the Land and Resources Science&Technology Project of Jiangsu Province(Grant No.2018045)。
文摘Soil-rock mixtures containing macropore(SRMCM)is a kind of geological material with special mechanical properties.Located in the project area of Lenggu hydropower station on the Yalong River,Sichuan Province,China,there is an extremely unstable Mahe talus slide with a total volume of nearly160 million cubic meters,which is mainly composed of SRMCM.The study on the mechanical properties of SRMCM is of great significance for the engineering construction and safe operation.In this paper,laboratory tests and discrete element numerical tests based on three-dimensional scanning technology were conducted to study the influence of stone content,stone size,and the angle of the macropore structure on shear characteristics of SRMCM.The failure mechanism of SRMCM was discussed from a microscopic perspective.This work explains the internal mechanism of the influence of stone content,stone size,and the angle of the macropore structure on the strength of SRMCM through the microscopic level of stone rotation,force chain distribution,and crack propagation.As the macropore structure that intersects with the preset shear plane at a large angle could act as a skeleton-like support to resist the shear force,the fracture of the weak cemented surface of soil and stone in the macropore structure is an important cause of SRMCM destruction.
基金provided by National Key Basic Research Development Program (Grant No.2013CB956702)
文摘With few available soil organic carbon(SOC)profiles and the heterogeneity of those that do exist, the estimation of SOC pools in karst areas is highly uncertain.Based on the spatial heterogeneity of SOC content of 23,536 samples in a karst watershed, a modified estimation method was determined for SOC storage that exclusively applies to karst areas. The method is a "soil-type method" based on revised calculation indexes for SOC storage. In the present study, the organic carbon contents of different soil types varied greatly, but generally decreased with increasing soil depth. The organic carbon content decreased nearly linearly to a depth of 0–50 cm and then varied at depths of 50–100 cm. Because of the large spatial variability in the karst area, we were able to determine that influences of the different indexes on the estimation of SOC storage decreased as follows: soil thickness > boulder content > rock fragment content > SOC content > bulk density. Using the modified formula, the SOC content in the Houzhai watershed in Puding was estimated to range from 3.53 to 5.44 kg m^(-2), with an average value of 1.24 kg m^(-2) to a depth of 20 cm, and from 4.44 to 14.50 kg m^(-2), with an average value of 12.12 kg m^(-2) to a depth of 100 cm. The total SOC content was estimated at 5.39*10^(5) t.
基金Scientific and Technological Support and Guidance Plan Projects of Zhejiang Province(Grant No.2008C23019)
文摘A self-developed elasto-plastic finite element program was used to analyze the construction sequence of high rock slope's stabilization in a coal-coking plant, and the result was compared with that employing the ultimate equilibrium method. Based on the results of finite element analysis, the stress contour graphs and displacement vector graphs at different construction steps were obtained, and the behavior of the slope during stabilization construction process was analyzed quantitatively. Based on the analysis of safety factors of three different schemes of stabilization and two different construction schemes, the assessment of stability and bracing design of the construction process were performed. The results show that the original reinforcement design is improper; the stability of the rock slope is controlled by a developed structural plane, the stability factor after excavation is less than 1, and the free surface should be braced in time; for stability, the construction sequence should adopt that bracing follows excavation step by step up to down; the local slide occurred during the construction process agrees with the dangerous slide determined by the numerical analysis, which proves the validity and rationality of the adopted method.
文摘By combing the characteristics of drilling in Antarctic region, performance requirements on drilling fluid for Antarctic low temperature conditions, and research progress of low temperature drilling fluid, current problems of the drilling fluid have been sorted out, and the development direction of the drilling fluid has been pointed out. Drilling in the Antarctic region mainly includes drilling in snow, ice and subglacial rock formations, and drilling in Antarctic low temperature conditions will face problems in four aspects:(1) low temperature and large temperature changes in the drilling area;(2) likely well leakage and drillstring-sticking in the snow layer, creep in the ice layer, ice chip gathering jamming in the warm ice layer, well wall collapse in the subglacial rock formations;(3) lack of infrastructure and difficulty in logistical support;(4) fragile environment and low carrying capacity. After years of development, progresses have been made on low-temperature drilling fluids for the Antarctic region. Low-temperature petroleum-based drilling fluid, ethanol/ethylene glycol-based drilling fluid, ester-based drilling fluid and silicone oil-based drilling fluid have been developed. However, these drilling fluids have problems such as insufficient low-temperature tolerance, low environmental performance and weak wellbore stability, etc. In order to meet the performance requirements of drilling fluid under low-temperature conditions in Antarctic region, the working mechanisms of low-temperature drilling fluid must be examined in depth;environment-friendly low-temperature base fluid of drilling fluid and related additives must be developed to prepare environmentally friendly low temperature drilling fluid systems;multi-functional integrated adjustment method for drilling fluid must be worked out to ensure well wall stability and improve cutting-carry capacity when drilling ice formations and ice-rock interlayers;and on-site support operation codes must be established to provide technical support for Antarctic drilling.
文摘The analysis of building structure in contact with soil involves an interactive process of stresses and strains developed within the structure and the soil field. The response of Piled-Raft Foundation system to the structure is very challenging because there is an important interplay between the component of building structure and the soil field. Herein, soil-foundation-structure interaction of buildings founded on Piled-Raft Foundation is evaluated through 3D-Nonlinear Finite Element Analyses using PLAXIS3D FOUNDATION code. The soil settlements and forces demand of the high-rise building structures and foundation is computed. The parametric study affecting the soil-foundation-structure response has been carried out. The parameters such as construction phasing, sequential loading, building aspect ratios, soil failure models and thickness proportion of soil field stiff layer, are considered. It is concluded that the interaction of building foundation-soil field and super-structure has remarkable effect on the structure.
文摘【目的】为了深入了解月面建造过程中月壤的力学特性,评估月基装备性能,优化月面建造作业,开展离散元法(discrete element method,DEM)在月壤接触力学领域的应用调查研究,旨在利用离散元法为未来月球基地建设提供理论指导和技术支持。【研究现状】基于地质勘探、资源采集及运输、建造作业等月面原位建造任务场景,分析月壤颗粒的建模与参数标定,介绍月基装备与月壤的接触作用研究现状,概述离散元法在钻-壤作用模拟、铲-壤作用模拟、轮-壤作用模拟及足-壤作用模拟中的应用,探讨基于离散元法的天然月基承载力分析。【结论与展望】提出降低几何模型复杂度、优化粒间接触模型及参数是提高宏观尺度月壤离散元建模精度以应对大规模月面建造场景的有效方法。认为利用离散元法进行铲挖式月壤采集装置及足式月球车设计在未来可以为月面建造提供可靠的技术支持。面向月面建造,离散元法将在水冰资源利用、建筑物月面承载力分析等方面提供科学依据。