The evolution due to temperature and pressure of shale reservoir permeability affects the productivity evaluation and development decision of shale gas reservoirs,which is very important for the exploration and develo...The evolution due to temperature and pressure of shale reservoir permeability affects the productivity evaluation and development decision of shale gas reservoirs,which is very important for the exploration and development of unconventional gas reservoirs.This study analyzed the coupling effects of temperature(25,50,and 75°C),effective stress(15 and 30 MPa),and pore pressure(0.5,2.0,4.0,and 8.0 MPa)on the permeability of the shale sample in the Longmaxi Formation.As the temperature and pressure increased,the apparent permeability exhibited a downward trend,and the absolute permeability decreased with the rise of temperature or effective stress.An in‐depth analysis of the gas slippage factors under the conditions of different temperature and pressure was conducted to evaluate the trend of the average pore width with temperature and pressure.The results were then verified by scanning electron microscopy(SEM).The results provide new insights into evaluating the permeability of the Longmaxi shale and can be used to enhance the gas recovery rate of deep shale gas reservoirs.展开更多
The traditional genetic algorithm(GA)has unstable inversion results and is easy to fall into the local optimum when inverting fault parameters.Therefore,this article considers the combination of GA with other non-line...The traditional genetic algorithm(GA)has unstable inversion results and is easy to fall into the local optimum when inverting fault parameters.Therefore,this article considers the combination of GA with other non-linear algorithms in order to improve the inversion precision of GA.This paper proposes a genetic Nelder-Mead neural network algorithm(GNMNNA).This algorithm uses a neural network algorithm(NNA)to optimize the global search ability of GA.At the same time,the simplex algorithm is used to optimize the local search capability of the GA.Through numerical examples,the stability of the inversion algorithm under different strategies is explored.The experimental results show that the proposed GNMNNA has stronger inversion stability and higher precision compared with the existing algorithms.The effectiveness of GNMNNA is verified by the BodrumeKos earthquake and Monte Cristo Range earthquake.The experimental results show that GNMNNA is superior to GA and NNA in both inversion precision and computational stability.Therefore,GNMNNA has greater application potential in complex earthquake environment.展开更多
At present,there are a large number of informal landfills to be treated all over the country. Under the condition of limited treatment funds,it is necessary to prioritize the treatment of informal landfills. In this p...At present,there are a large number of informal landfills to be treated all over the country. Under the condition of limited treatment funds,it is necessary to prioritize the treatment of informal landfills. In this paper,the pollution risk of waste dump,surrounding soil,groundwater and surface water is analyzed,and a set of comprehensive risk assessment method system of informal landfill is established,which could provide reference for decision making department deciding landfill disposal.展开更多
Two kinds of determining methods for scenario earthquakes are presented in this paper,namely the weighted average method and maximum probability method. This paper briefly introduces the two methods,then taking a high...Two kinds of determining methods for scenario earthquakes are presented in this paper,namely the weighted average method and maximum probability method. This paper briefly introduces the two methods,then taking a high-rise building in the Yantai area as a case study,we use the weighted average method and maximum probability method to realize seismic hazard analysis, determine earthquake magnitude, the epicenter and specific space position,and then give two response spectrums of the two methods. By comparing the differences of response spectrums between the two methods,we find that the weighted average method is more suitable for long period structures,while considering long period safety. The maximum probability method is more suitable for short period structures. It is reasonable to choose a corresponding different method when the structures have different natural vibration periods.展开更多
As an industry and a discipline,geotechnical investigation in China differs from that in the USA and European countries in its course of emergence and evolution. For over half a century,Chinese geotechnical investigat...As an industry and a discipline,geotechnical investigation in China differs from that in the USA and European countries in its course of emergence and evolution. For over half a century,Chinese geotechnical investigation professionals witnessed continuous technical advances as they undertook independently almost all of China's large-scale construction projects. Based on projects that won the "National Outstanding Engineering Investigation" Gold Medal Awards since the year 2000,this paper discusses the achievements of geotechnical investigation in the context of comprehensive technical ability,project evaluation and analysis,hi-tech applications and engineering monitoring,and analyzes several factors that have hindered the industry's further development and alignment with international practice. Finally,some suggestions are given for future improvement.展开更多
Mechanical soil aeration is a simple, effective, and low-cost soil remediation technology that is suitable for sites contaminated with volatile chlorinated hydrocarbons（VCHs）. Conventionally, this technique is used ...Mechanical soil aeration is a simple, effective, and low-cost soil remediation technology that is suitable for sites contaminated with volatile chlorinated hydrocarbons（VCHs）. Conventionally, this technique is used to treat the mixed soil of a site without considering the diversity and treatability of different soils within the site. A laboratory test was conducted to evaluate the effectiveness of mechanical soil aeration for remediating soils of different textures（silty,clayey, and sandy soils） along a vertical profile at an abandoned chloro-alkali chemical site in China. The collected soils were artificially contaminated with chloroform（TCM） and trichloroethylene（TCE）. Mechanical soil aeration was effective for remediating VCHs（removal efficiency 〉 98%）. The volatilization process was described by an exponential kinetic function.In the early stage of treatment（0–7 hr）, rapid contaminant volatilization followed a pseudofirst order kinetic model. VCH concentrations decreased to low levels and showed a tailing phenomenon with very slow contaminant release after 8 hr. Compared with silty and sandy soils, clayey soil has high organic-matter content, a large specific surface area, a high clay fraction, and a complex pore structure. These characteristics substantially influenced the removal process, making it less efficient, more time consuming, and consequently more expensive. Our findings provide a potential basis for optimizing soil remediation strategy in a cost-effective manner.展开更多
基金National Natural Science Foundations of China,Grant/Award Numbers:51809264,52178375,52211530088Fundamental Research Funds for the Central Universities,Grant/Award Number:2023ZKPYLJ06。
文摘The evolution due to temperature and pressure of shale reservoir permeability affects the productivity evaluation and development decision of shale gas reservoirs,which is very important for the exploration and development of unconventional gas reservoirs.This study analyzed the coupling effects of temperature(25,50,and 75°C),effective stress(15 and 30 MPa),and pore pressure(0.5,2.0,4.0,and 8.0 MPa)on the permeability of the shale sample in the Longmaxi Formation.As the temperature and pressure increased,the apparent permeability exhibited a downward trend,and the absolute permeability decreased with the rise of temperature or effective stress.An in‐depth analysis of the gas slippage factors under the conditions of different temperature and pressure was conducted to evaluate the trend of the average pore width with temperature and pressure.The results were then verified by scanning electron microscopy(SEM).The results provide new insights into evaluating the permeability of the Longmaxi shale and can be used to enhance the gas recovery rate of deep shale gas reservoirs.
基金This manuscript is supported by the National Natural Science Foundation of China(No.42174011,41874001 and 42174011).
文摘The traditional genetic algorithm(GA)has unstable inversion results and is easy to fall into the local optimum when inverting fault parameters.Therefore,this article considers the combination of GA with other non-linear algorithms in order to improve the inversion precision of GA.This paper proposes a genetic Nelder-Mead neural network algorithm(GNMNNA).This algorithm uses a neural network algorithm(NNA)to optimize the global search ability of GA.At the same time,the simplex algorithm is used to optimize the local search capability of the GA.Through numerical examples,the stability of the inversion algorithm under different strategies is explored.The experimental results show that the proposed GNMNNA has stronger inversion stability and higher precision compared with the existing algorithms.The effectiveness of GNMNNA is verified by the BodrumeKos earthquake and Monte Cristo Range earthquake.The experimental results show that GNMNNA is superior to GA and NNA in both inversion precision and computational stability.Therefore,GNMNNA has greater application potential in complex earthquake environment.
文摘At present,there are a large number of informal landfills to be treated all over the country. Under the condition of limited treatment funds,it is necessary to prioritize the treatment of informal landfills. In this paper,the pollution risk of waste dump,surrounding soil,groundwater and surface water is analyzed,and a set of comprehensive risk assessment method system of informal landfill is established,which could provide reference for decision making department deciding landfill disposal.
基金funded by the Basic Scientific Research and Business Item of Central Public-interest Scientific Institution,China(ZDJ2012-12)
文摘Two kinds of determining methods for scenario earthquakes are presented in this paper,namely the weighted average method and maximum probability method. This paper briefly introduces the two methods,then taking a high-rise building in the Yantai area as a case study,we use the weighted average method and maximum probability method to realize seismic hazard analysis, determine earthquake magnitude, the epicenter and specific space position,and then give two response spectrums of the two methods. By comparing the differences of response spectrums between the two methods,we find that the weighted average method is more suitable for long period structures,while considering long period safety. The maximum probability method is more suitable for short period structures. It is reasonable to choose a corresponding different method when the structures have different natural vibration periods.
文摘As an industry and a discipline,geotechnical investigation in China differs from that in the USA and European countries in its course of emergence and evolution. For over half a century,Chinese geotechnical investigation professionals witnessed continuous technical advances as they undertook independently almost all of China's large-scale construction projects. Based on projects that won the "National Outstanding Engineering Investigation" Gold Medal Awards since the year 2000,this paper discusses the achievements of geotechnical investigation in the context of comprehensive technical ability,project evaluation and analysis,hi-tech applications and engineering monitoring,and analyzes several factors that have hindered the industry's further development and alignment with international practice. Finally,some suggestions are given for future improvement.
基金supported by the National Environmental Protection Public Welfare projects(Nos.201409047 and 201109017)the “13th Five-Year Plan” National Key Research and Development Program of China(No.2016YFC0501108)+1 种基金the Fundamental Research Funds for the Central Universities(No.2016QH02)Beijing Natural Science Foundation(No.8152025)
文摘Mechanical soil aeration is a simple, effective, and low-cost soil remediation technology that is suitable for sites contaminated with volatile chlorinated hydrocarbons（VCHs）. Conventionally, this technique is used to treat the mixed soil of a site without considering the diversity and treatability of different soils within the site. A laboratory test was conducted to evaluate the effectiveness of mechanical soil aeration for remediating soils of different textures（silty,clayey, and sandy soils） along a vertical profile at an abandoned chloro-alkali chemical site in China. The collected soils were artificially contaminated with chloroform（TCM） and trichloroethylene（TCE）. Mechanical soil aeration was effective for remediating VCHs（removal efficiency 〉 98%）. The volatilization process was described by an exponential kinetic function.In the early stage of treatment（0–7 hr）, rapid contaminant volatilization followed a pseudofirst order kinetic model. VCH concentrations decreased to low levels and showed a tailing phenomenon with very slow contaminant release after 8 hr. Compared with silty and sandy soils, clayey soil has high organic-matter content, a large specific surface area, a high clay fraction, and a complex pore structure. These characteristics substantially influenced the removal process, making it less efficient, more time consuming, and consequently more expensive. Our findings provide a potential basis for optimizing soil remediation strategy in a cost-effective manner.
