1997 Vol. 19 No. 6
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Abstract：
Twin shear unified elasto-plastic associated and non-associated constitutive model, which is based on the Twin Shear Unified Strength Theory Yu,1991, is proposed in this paper. The authors give a classification of singularities and discusses their solutions of the proposed unified elasto-plastic constitutive model, which are also applicable to singular yield surface such as Tresca, Mohr-Coulomb and others. This unified consitutive model has been implemented in UEPP (Unified Elasto-Plastic finite element Program). Twin Shear Unified Strength Theory (or Unified Strength Theory), unified elastoplastic constitutive model and UEPP constitute a comprehensive system of elasto-plastic theoretical analysis, finite element implementation and engineering application.
Twin shear unified elasto-plastic associated and non-associated constitutive model, which is based on the Twin Shear Unified Strength Theory Yu,1991, is proposed in this paper. The authors give a classification of singularities and discusses their solutions of the proposed unified elasto-plastic constitutive model, which are also applicable to singular yield surface such as Tresca, Mohr-Coulomb and others. This unified consitutive model has been implemented in UEPP (Unified Elasto-Plastic finite element Program). Twin Shear Unified Strength Theory (or Unified Strength Theory), unified elastoplastic constitutive model and UEPP constitute a comprehensive system of elasto-plastic theoretical analysis, finite element implementation and engineering application.
Abstract：
A new method for determining the rock damage range is presented for the first time on the basis of combining seismic tomography technique and elastic wave method. In addtion, the critical vibration speed in the jointed rock mass in Three Gorges Project is studied with the help of the attenuation equation for blasting seismic wave.
A new method for determining the rock damage range is presented for the first time on the basis of combining seismic tomography technique and elastic wave method. In addtion, the critical vibration speed in the jointed rock mass in Three Gorges Project is studied with the help of the attenuation equation for blasting seismic wave.
Abstract：
A method based on the stress-wave theory to estimate the static resistance at pile toe during pile driving has been developed. In this method, the static resistance at pile toe can be calculated directly with the rebound at pile top and impulse duration from the acceleration signal at pile top. Compared with CPT, CASE method and blowcount test, the result is more reliable and almost independent of soil-damping, ram-drop-height and cushion-stiffness. The method can be used to estimate the bearing capacity of single pile and to control the depth of pile to be drived.
A method based on the stress-wave theory to estimate the static resistance at pile toe during pile driving has been developed. In this method, the static resistance at pile toe can be calculated directly with the rebound at pile top and impulse duration from the acceleration signal at pile top. Compared with CPT, CASE method and blowcount test, the result is more reliable and almost independent of soil-damping, ram-drop-height and cushion-stiffness. The method can be used to estimate the bearing capacity of single pile and to control the depth of pile to be drived.
Abstract：
Based on the theoretics of Model Identifying, Fuzzy Mathematics, Directional Graph, and the relationship between roof movement and abutment manifestation, the method of graph element and nearing predicting span for analysing the information of roof movement are proposed. This is the key techniqe to realize automatic forecasting roof weighting. The technique has been applied in four mines.
Based on the theoretics of Model Identifying, Fuzzy Mathematics, Directional Graph, and the relationship between roof movement and abutment manifestation, the method of graph element and nearing predicting span for analysing the information of roof movement are proposed. This is the key techniqe to realize automatic forecasting roof weighting. The technique has been applied in four mines.
Abstract：
The vibration problem of finite length foundation pile under exciting force taking account of rheological properties of the surrounding soil is studied, and the corresponding analytical solution is developed. Based on the solution, the influences of the parameters of pile and soil on the vibration are analysed and some relevant conclusions are drawn. the theoretical curves are in good agreement with that obtained from the field measurement.
The vibration problem of finite length foundation pile under exciting force taking account of rheological properties of the surrounding soil is studied, and the corresponding analytical solution is developed. Based on the solution, the influences of the parameters of pile and soil on the vibration are analysed and some relevant conclusions are drawn. the theoretical curves are in good agreement with that obtained from the field measurement.
Abstract：
This paper presents a nonlinear interaction method for computing inner force and displacement of arch retaining structure. Engineering examples illustrates the feasibility and validity of this method. It provides a valid computation method for getting reasonable form of arch retaining structure.
This paper presents a nonlinear interaction method for computing inner force and displacement of arch retaining structure. Engineering examples illustrates the feasibility and validity of this method. It provides a valid computation method for getting reasonable form of arch retaining structure.
Abstract：
The test results of large-grain diameter vibro replacement stone column in situ at xinhui′s Tianma Port of Guangdong are introduced. They includes:①the six sets of shear test for φ150cm and φ100cm in diameter on the stone column,②large-scale slide test, and ③the five sets of loading test. Directly the ideal results have been achieved and applied, by the above tests, to the consolidation of soft groand of 10000 dwt in two Quay at Tianma Port and Dongguan Shatian Port. The projects have been achieved completion and the results are ideal.
The test results of large-grain diameter vibro replacement stone column in situ at xinhui′s Tianma Port of Guangdong are introduced. They includes:①the six sets of shear test for φ150cm and φ100cm in diameter on the stone column,②large-scale slide test, and ③the five sets of loading test. Directly the ideal results have been achieved and applied, by the above tests, to the consolidation of soft groand of 10000 dwt in two Quay at Tianma Port and Dongguan Shatian Port. The projects have been achieved completion and the results are ideal.
Abstract：
This paper investigates the initiation and growth criteria for compression-shear crack and provides theoretical analysis for former experience compression-shear fracture criterion. On the basis of compression-shear crack model, the compression-shear damage model for rock mass is proposed with crack closing effect and crack interacting. From the proposed model, it is found that rockburst results from macroscopic brittle fracture of rock mass due to frictional sliding, interface propagating, kinking, and linking of preexisting cracks in rock mass activated by stress redistributing (tangetial stress concentrating and radial stress relieving) of surrounding rock mass during (or after) excavating of underground carven. Numerical simulations indicate that the results from proposed models can simulate available experimental results very well and crack closing stress has a significant influence on the stress-strain relationship of rock mass. It is shown that the damage strains, especially the lateral strain, increase with the raise of the crack closing stress.
This paper investigates the initiation and growth criteria for compression-shear crack and provides theoretical analysis for former experience compression-shear fracture criterion. On the basis of compression-shear crack model, the compression-shear damage model for rock mass is proposed with crack closing effect and crack interacting. From the proposed model, it is found that rockburst results from macroscopic brittle fracture of rock mass due to frictional sliding, interface propagating, kinking, and linking of preexisting cracks in rock mass activated by stress redistributing (tangetial stress concentrating and radial stress relieving) of surrounding rock mass during (or after) excavating of underground carven. Numerical simulations indicate that the results from proposed models can simulate available experimental results very well and crack closing stress has a significant influence on the stress-strain relationship of rock mass. It is shown that the damage strains, especially the lateral strain, increase with the raise of the crack closing stress.
Abstract：
A two dimensional plane-stress finite-element type of analysis is presented to predict the behaviour of geogrids embedded in fill material under pullout loading conditions. The interactions between fill material and geogrid are simulated by nonlinear springs. The stiffnesses of the springs can be determined from simple tests in a specially designed shear box. The proposed FE analysis is applied to interpret test results from a large scale pullout test rig. The predicted behaviour of the geogrid under pullout load agrees well with the observed data including the load-displacement properties, the displacement distribution along the longitudinal direction and the mobilization of the frictional and bearing resistance.
A two dimensional plane-stress finite-element type of analysis is presented to predict the behaviour of geogrids embedded in fill material under pullout loading conditions. The interactions between fill material and geogrid are simulated by nonlinear springs. The stiffnesses of the springs can be determined from simple tests in a specially designed shear box. The proposed FE analysis is applied to interpret test results from a large scale pullout test rig. The predicted behaviour of the geogrid under pullout load agrees well with the observed data including the load-displacement properties, the displacement distribution along the longitudinal direction and the mobilization of the frictional and bearing resistance.
Abstract：
In this study,the soil was obtained from insitu material in nearshore area of YunLin Industrial Estate.By using sea water as pore media,and using the hydraulic simulation method developed by Chien(1993) in laboratory,the packing properties of the recliamed soil is discussed.Using the traditional moist tamping method,the specimen are prepared with different relative density and fines content,and Rowetype consolidation test are conducted.The inflences of packing properties,fines content,relative density,and pore media are discussed,so that the consolidation settlement behavior are evaluated.In the study,cyclic dynamic load test are conducted by using the Rowetype consolidation cell,to evaluate the influence of earthquake or cyclic stress on recliamed soil.As shown in the results,dynamic loading has distinct influence on the consolidation settlement properties of reclaimed soil.Under 60 number of cycles,the average settlement value for dynamic consoildation settlement is 2 times larger than static consoildation settlement.The test results and the related consolidation relations can be used for land reclamation and coastal design,and research purposes.
In this study,the soil was obtained from insitu material in nearshore area of YunLin Industrial Estate.By using sea water as pore media,and using the hydraulic simulation method developed by Chien(1993) in laboratory,the packing properties of the recliamed soil is discussed.Using the traditional moist tamping method,the specimen are prepared with different relative density and fines content,and Rowetype consolidation test are conducted.The inflences of packing properties,fines content,relative density,and pore media are discussed,so that the consolidation settlement behavior are evaluated.In the study,cyclic dynamic load test are conducted by using the Rowetype consolidation cell,to evaluate the influence of earthquake or cyclic stress on recliamed soil.As shown in the results,dynamic loading has distinct influence on the consolidation settlement properties of reclaimed soil.Under 60 number of cycles,the average settlement value for dynamic consoildation settlement is 2 times larger than static consoildation settlement.The test results and the related consolidation relations can be used for land reclamation and coastal design,and research purposes.
Abstract：
The flood embankment by city Anqing is a typicalreach of levees along Yangtze River.Its foundation is strong permeability with deeper sand deposits overburden complicated soil layers of weak permeability.Although 100 more relief wells had constructed at landside toe of the embankment but never attained the presupposed effect due to silting year by year.In this paper the present state and tendency of silting gradually in relief wells is verified by analyzing data of field observation.By experiments in laboratory and field a washing method to restore well relieving effect was found.With FEM the 2-D seepage flow computation for 7 typical sections was conducted.After comparison of effects for different seepage control measures the different strengthening schemes such as overburden layer thickened inside,cut-off sand layers,maintainingdrainage line of original relief wells etc. were proposed individually for different reaches of the embankment.
The flood embankment by city Anqing is a typicalreach of levees along Yangtze River.Its foundation is strong permeability with deeper sand deposits overburden complicated soil layers of weak permeability.Although 100 more relief wells had constructed at landside toe of the embankment but never attained the presupposed effect due to silting year by year.In this paper the present state and tendency of silting gradually in relief wells is verified by analyzing data of field observation.By experiments in laboratory and field a washing method to restore well relieving effect was found.With FEM the 2-D seepage flow computation for 7 typical sections was conducted.After comparison of effects for different seepage control measures the different strengthening schemes such as overburden layer thickened inside,cut-off sand layers,maintainingdrainage line of original relief wells etc. were proposed individually for different reaches of the embankment.
Abstract：
Taking a real sixstorey twospan frame building for exemple, the soilframe structure system is simplied as twodimensional question, Soils are regarded as viscoelastic material, and frame structure is regarded as a nonelastic plane struture of bar system being composed of variable stiffness beam elements. The shock absorbing characteristics of tuned mass damper (TMD) and the effect of the soilstructure interaction(SSI) on the shock absorbing efficiency(SAE) are discussed in detail. In the condition of midsoft to midhard ground the effect of SSI can obviously reduce the storey displacement in range of 10% to 50% for multistorey framed building during earthquake. The SAE of TMD is best only when the vibration period of TMD is equation to the basic periods of (soils and) structure system being control, if not, the SAE of TMD will be reduced in range of 5% to 10%. On the soft ground condition the SAE of TMD almost lost due to SSI effects. It can be not necessary in some condition that TMD is adopted in structure designed by the assumption of rigid ground if the SSI effects are considered in the seismic design.
Taking a real sixstorey twospan frame building for exemple, the soilframe structure system is simplied as twodimensional question, Soils are regarded as viscoelastic material, and frame structure is regarded as a nonelastic plane struture of bar system being composed of variable stiffness beam elements. The shock absorbing characteristics of tuned mass damper (TMD) and the effect of the soilstructure interaction(SSI) on the shock absorbing efficiency(SAE) are discussed in detail. In the condition of midsoft to midhard ground the effect of SSI can obviously reduce the storey displacement in range of 10% to 50% for multistorey framed building during earthquake. The SAE of TMD is best only when the vibration period of TMD is equation to the basic periods of (soils and) structure system being control, if not, the SAE of TMD will be reduced in range of 5% to 10%. On the soft ground condition the SAE of TMD almost lost due to SSI effects. It can be not necessary in some condition that TMD is adopted in structure designed by the assumption of rigid ground if the SSI effects are considered in the seismic design.
