In view of the planning practices of Hexi Village,Chini Town,Huadu District,Guangzhou City,general situation of the village was introduced,"ecological, convenient,high-efficiency,sharable"were taken as princ...In view of the planning practices of Hexi Village,Chini Town,Huadu District,Guangzhou City,general situation of the village was introduced,"ecological, convenient,high-efficiency,sharable"were taken as principles for the village planning.The village planning was elaborated from 4 perspectives:coordination between town planning and village planning,comprehensive village planning,renovation of old village,construction planning of new village.The implementation projects were summarized to discuss village planning.And it was proposed that the village planning should use construction land intensively and demonstrate regional characteristics.展开更多
In order to study the rheological properties of red stone granular soil,a series of rheological experiments were executed on large tri-axial rheological apparatus.Under 100,200 and 300 kPa confining stress conditions,...In order to study the rheological properties of red stone granular soil,a series of rheological experiments were executed on large tri-axial rheological apparatus.Under 100,200 and 300 kPa confining stress conditions,the rheological tests were carried out.These experiment results showed that the stress conditions,especially the stress level were the critical influencing factors of the rheological deformation properties.Under the low stress level(S=0.1),the granular soil showed the elastic properties,and there was no obvious rheological deformation.Under the middle stress level(0.2<S≤0.6),creep curves showed the linear viscoelastic rheological properties.However,under the high stress level(S>0.8) creep curves showed the non-linear viscous plastic rheological properties.Especially,under the stress level of S=1.0,the accelerated rheological phase of creep curves occurred at early time with a trend of failure.The stress level had obvious effects on the final rheological deformation of the soil sample,and the final rheological deformation increments nonlinearly increased with stress level.The final rheological deformation increment and step was little under low stress level,while it became large under high stress level,which showed the nonlinearly rheological properties of the granular soil.The confining pressure also had direct effects on final rheological deformation,and the final rheological deformation linearly increased with confining pressure increments.展开更多
Shale,as a kind of brittle rock,often exhibits different nonlinear stress-strain behavior,failure and timedependent behavior under different strain rates.To capture these features,this work conducted triaxial compress...Shale,as a kind of brittle rock,often exhibits different nonlinear stress-strain behavior,failure and timedependent behavior under different strain rates.To capture these features,this work conducted triaxial compression tests under axial strain rates ranging from 5×10-6 s-1 to 1×10-3 s-1.The results show that both elastic modulus and peak strength have a positive correlation relationship with strain rates.These strain rate-dependent mechanical behaviors of shale are originated from damage growth,which is described by a damage parameter.When axial strain is the same,the damage parameter is positively correlated with strain rate.When strain rate is the same,with an increase of axial strain,the damage parameter decreases firstly from an initial value(about 0.1 to 0.2),soon reaches its minimum(about 0.1),and then increases to an asymptotic value of 0.8.Based on the experimental results,taking yield stress as the cut-off point and considering damage variable evolution,a new measure of micro-mechanical strength is proposed.Based on the Lemaitre’s equivalent strain assumption and the new measure of micro-mechanical strength,a statistical strain-rate dependent damage constitutive model for shale that couples physically meaningful model parameters was established.Numerical back-calculations of these triaxial compression tests results demonstrate the ability of the model to reproduce the primary features of the strain rate dependent mechanical behavior of shale.展开更多
According to the basic idea of classical yin-yang complementarity and modern dual-complementarity, in a simple and unified way proposed by Luo(1987), some uncon ventional Hamilton-type variational principles for dyn...According to the basic idea of classical yin-yang complementarity and modern dual-complementarity, in a simple and unified way proposed by Luo(1987), some uncon ventional Hamilton-type variational principles for dynamics of Reissner sandwich plate can be established systematically. The unconventional Hamilton-type variation principle can fully characterize the initial boundary value problem of this dynamics. In this paper, an important integral relation is given, which can be considered as the generalized principle of virtual work in mechanics. Based on this relation, it is possible not only to obtain the principle of virtual work in dynamics of Reissner sandwich plate, but also to derive systematically the complementary functionals for fivefield, two-field and one-field unconventional Hamilton-type variational principles by the generalized Legender transformations. Furthermore, with this approach, the intrinsic relationship among the various principles can be explained clearly.展开更多
Considering compression of solid grain and pore fluids,viscous-coupling interactions and inertial force of fluids,dynamic governing equations for unsaturated soils are established by adopting an exact constitutive for...Considering compression of solid grain and pore fluids,viscous-coupling interactions and inertial force of fluids,dynamic governing equations for unsaturated soils are established by adopting an exact constitutive formula of saturation.These equations are highly versatile and completely compatible with Biot's wave equations for the special case of fully saturated soils.The governing equations in Cartesian coordinates are firstly transformed into a group of state differential equations by introducing the state vector.Then the transfer matrix for layered media are derived by means of a double Fourier transform.Using the transfer matrix followed by boundary and continuity conditions between strata,solutions of steady-state dynamic response for multi-layered unsaturated soils are obtained.Numerical examples show that the echoes generated by boundary and stratum interfaces make the displacement amplitude of the ground surface fluctuate with distance;the relative position of soft and hard strata has a significant influence on displacement.展开更多
The accurate estimation of fracture geometry parameters and the characterization of rock mass structure are two important topics in the geological disposal system of high-level radioactive waste(HLW).The Beishan area,...The accurate estimation of fracture geometry parameters and the characterization of rock mass structure are two important topics in the geological disposal system of high-level radioactive waste(HLW).The Beishan area,as the current preselected area for China’s HLW disposal,has three subareas considered to be the key survey area at the stage of site selection.In this paper,a comprehensive survey method conducted on the outcrop is developed to estimate fracture geometry parameters.Results show that fracture occurrence obeys a Fisher distribution,fracture trace length obeys a normal distribution,and the distribution of spacing obeys a negative exponential distribution.An evaluation index,Rock Mass Structure Rating(RMSR),is proposed to characterize rock mass structure for the three subareas.The results show that the Xinchang area is more suitable to act as China’s HLW disposal repository site.At the same time,the index can also be applied to characterize surface rock mass structure and rock mass integrity at the site selection phase of HLW disposal.展开更多
The U-value is a very important parameter for evaluating the energy efficiency when refurbishing the existing buildings.Traditional in-situ test methods to determine the U-value usually require a very long time to fil...The U-value is a very important parameter for evaluating the energy efficiency when refurbishing the existing buildings.Traditional in-situ test methods to determine the U-value usually require a very long time to filter weather fluctuations and other boundary condition influences.In this paper,the possibility of a new method to reduce the time necessitated for measuring the accurate U-value of a wall is tested.The proposed method recommends measuring the temperatures and heat flux on both sides of the wall and thereby utilising the average values of the internal and external heat flux to calculate the U-value.Under the idealised sinusoidal internal and external air temperature boundary conditions,four walls with different U-values were simulated according to the admittance procedure(AP).Results show that the proposed method could improve the maximum error level for most of the walls in consideration.It was not sensitive to the measurement start time and it was more stable even in less controlled boundary conditions involving large inner temperature variations or out of phase temperature waves.Besides,the error of the average heat flux method(within 10%)could be estimated earlier than that of traditional method.展开更多
文摘In view of the planning practices of Hexi Village,Chini Town,Huadu District,Guangzhou City,general situation of the village was introduced,"ecological, convenient,high-efficiency,sharable"were taken as principles for the village planning.The village planning was elaborated from 4 perspectives:coordination between town planning and village planning,comprehensive village planning,renovation of old village,construction planning of new village.The implementation projects were summarized to discuss village planning.And it was proposed that the village planning should use construction land intensively and demonstrate regional characteristics.
基金Project(200413) supported by Communication Science and Technology Fund of Hunan Province,China
文摘In order to study the rheological properties of red stone granular soil,a series of rheological experiments were executed on large tri-axial rheological apparatus.Under 100,200 and 300 kPa confining stress conditions,the rheological tests were carried out.These experiment results showed that the stress conditions,especially the stress level were the critical influencing factors of the rheological deformation properties.Under the low stress level(S=0.1),the granular soil showed the elastic properties,and there was no obvious rheological deformation.Under the middle stress level(0.2<S≤0.6),creep curves showed the linear viscoelastic rheological properties.However,under the high stress level(S>0.8) creep curves showed the non-linear viscous plastic rheological properties.Especially,under the stress level of S=1.0,the accelerated rheological phase of creep curves occurred at early time with a trend of failure.The stress level had obvious effects on the final rheological deformation of the soil sample,and the final rheological deformation increments nonlinearly increased with stress level.The final rheological deformation increment and step was little under low stress level,while it became large under high stress level,which showed the nonlinearly rheological properties of the granular soil.The confining pressure also had direct effects on final rheological deformation,and the final rheological deformation linearly increased with confining pressure increments.
基金financially supported by the China Scholarship Council projectthe National Natural Science Foundation of China(grants No.51574218,41688103,51678171,51608139,U1704243 and 51709113)+4 种基金the Guangdong Science and Technology Department(grant No.2015B020238014)the Guangzhou Science Technology and Innovation Commission(grant No.201604016021)the High-level Talent Research Launch Project(grant No.950318066)the Shandong Provincial Natural Science Foundation,China(grants No.ZR2017PD001 and ZR2018BD013)the Science Foundation of Chinese Academy of Geological Sciences(grant No.JYYWF20181201)
文摘Shale,as a kind of brittle rock,often exhibits different nonlinear stress-strain behavior,failure and timedependent behavior under different strain rates.To capture these features,this work conducted triaxial compression tests under axial strain rates ranging from 5×10-6 s-1 to 1×10-3 s-1.The results show that both elastic modulus and peak strength have a positive correlation relationship with strain rates.These strain rate-dependent mechanical behaviors of shale are originated from damage growth,which is described by a damage parameter.When axial strain is the same,the damage parameter is positively correlated with strain rate.When strain rate is the same,with an increase of axial strain,the damage parameter decreases firstly from an initial value(about 0.1 to 0.2),soon reaches its minimum(about 0.1),and then increases to an asymptotic value of 0.8.Based on the experimental results,taking yield stress as the cut-off point and considering damage variable evolution,a new measure of micro-mechanical strength is proposed.Based on the Lemaitre’s equivalent strain assumption and the new measure of micro-mechanical strength,a statistical strain-rate dependent damage constitutive model for shale that couples physically meaningful model parameters was established.Numerical back-calculations of these triaxial compression tests results demonstrate the ability of the model to reproduce the primary features of the strain rate dependent mechanical behavior of shale.
基金Project supported by the National Natural Science Foundation of China(No.10172097)the Doctoral Foundation of Ministry of Education of China(No.20030558025)
文摘According to the basic idea of classical yin-yang complementarity and modern dual-complementarity, in a simple and unified way proposed by Luo(1987), some uncon ventional Hamilton-type variational principles for dynamics of Reissner sandwich plate can be established systematically. The unconventional Hamilton-type variation principle can fully characterize the initial boundary value problem of this dynamics. In this paper, an important integral relation is given, which can be considered as the generalized principle of virtual work in mechanics. Based on this relation, it is possible not only to obtain the principle of virtual work in dynamics of Reissner sandwich plate, but also to derive systematically the complementary functionals for fivefield, two-field and one-field unconventional Hamilton-type variational principles by the generalized Legender transformations. Furthermore, with this approach, the intrinsic relationship among the various principles can be explained clearly.
基金National Natural Science Foundation of China(No.10272046)
文摘Considering compression of solid grain and pore fluids,viscous-coupling interactions and inertial force of fluids,dynamic governing equations for unsaturated soils are established by adopting an exact constitutive formula of saturation.These equations are highly versatile and completely compatible with Biot's wave equations for the special case of fully saturated soils.The governing equations in Cartesian coordinates are firstly transformed into a group of state differential equations by introducing the state vector.Then the transfer matrix for layered media are derived by means of a double Fourier transform.Using the transfer matrix followed by boundary and continuity conditions between strata,solutions of steady-state dynamic response for multi-layered unsaturated soils are obtained.Numerical examples show that the echoes generated by boundary and stratum interfaces make the displacement amplitude of the ground surface fluctuate with distance;the relative position of soft and hard strata has a significant influence on displacement.
基金supported by the National Key Research and Development Program of China,under grant No.2018YFC1504903the Chongqing Natural Science Foundation,under grant No.cstc2020jcyj-msxm X0743 and cstc 2020jcyj-bsh0142+3 种基金the Open Research Fund of the State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,under grant No.Z019018China postdoctoral science foundation Grant No.2019M662918 and 2020M673152Regional Joint Fund for Basic and Applied Basic Research Fund of Guangdong Province,No.2019A1515110836the National Natural Science Foundation of China,under grant No.41688103。
文摘The accurate estimation of fracture geometry parameters and the characterization of rock mass structure are two important topics in the geological disposal system of high-level radioactive waste(HLW).The Beishan area,as the current preselected area for China’s HLW disposal,has three subareas considered to be the key survey area at the stage of site selection.In this paper,a comprehensive survey method conducted on the outcrop is developed to estimate fracture geometry parameters.Results show that fracture occurrence obeys a Fisher distribution,fracture trace length obeys a normal distribution,and the distribution of spacing obeys a negative exponential distribution.An evaluation index,Rock Mass Structure Rating(RMSR),is proposed to characterize rock mass structure for the three subareas.The results show that the Xinchang area is more suitable to act as China’s HLW disposal repository site.At the same time,the index can also be applied to characterize surface rock mass structure and rock mass integrity at the site selection phase of HLW disposal.
文摘The U-value is a very important parameter for evaluating the energy efficiency when refurbishing the existing buildings.Traditional in-situ test methods to determine the U-value usually require a very long time to filter weather fluctuations and other boundary condition influences.In this paper,the possibility of a new method to reduce the time necessitated for measuring the accurate U-value of a wall is tested.The proposed method recommends measuring the temperatures and heat flux on both sides of the wall and thereby utilising the average values of the internal and external heat flux to calculate the U-value.Under the idealised sinusoidal internal and external air temperature boundary conditions,four walls with different U-values were simulated according to the admittance procedure(AP).Results show that the proposed method could improve the maximum error level for most of the walls in consideration.It was not sensitive to the measurement start time and it was more stable even in less controlled boundary conditions involving large inner temperature variations or out of phase temperature waves.Besides,the error of the average heat flux method(within 10%)could be estimated earlier than that of traditional method.