1980 Vol. 2 No. 3
Abstract：
This paper pointes out features of slide of the dam slope made of saturated cohesionless soils during earthquake. It is difficult to explain these features with the pseudo-static method. A procedure of analysis to seismic stability of such dam slope is presented and its every step is described in detail.
This paper pointes out features of slide of the dam slope made of saturated cohesionless soils during earthquake. It is difficult to explain these features with the pseudo-static method. A procedure of analysis to seismic stability of such dam slope is presented and its every step is described in detail.
Abstract：
The visco-elastoplatic soil model, introduced in this paper, is consistent with the experimental relationships, such as shear modulus vs shear strain, damping ratio vs shear strain, pore pressure ratio vs cycle ratio and stress ratio vs number of liquefaction cycles, etc. The loading-reloading rules control the hysteresis loops beneath skeleton curve. The "apparent applied forces"method is suggested to evaluate the effects of soil viscosity. The generations of pore pressure are evaluated by"fraction cycle method", which is simple and effective, especially for waved increases of pore water pressure.The soil model have been applied to a computer program （SRHSL-1978） for the total stress analysis of seismic response of site soil.
The visco-elastoplatic soil model, introduced in this paper, is consistent with the experimental relationships, such as shear modulus vs shear strain, damping ratio vs shear strain, pore pressure ratio vs cycle ratio and stress ratio vs number of liquefaction cycles, etc. The loading-reloading rules control the hysteresis loops beneath skeleton curve. The "apparent applied forces"method is suggested to evaluate the effects of soil viscosity. The generations of pore pressure are evaluated by"fraction cycle method", which is simple and effective, especially for waved increases of pore water pressure.The soil model have been applied to a computer program （SRHSL-1978） for the total stress analysis of seismic response of site soil.
Abstract：
This Paper reports the use of steady-state vibration technique in in-situ measurement of Rayliegh wave velocity, within certain exciting frequency range, in saturated cohesive soils at Gaoqiao District, Shanghai.This paper also reviews factors affecting wave velocity, with computed values of shear wave velocity, dynamic shear and elastic moduli etc.
This Paper reports the use of steady-state vibration technique in in-situ measurement of Rayliegh wave velocity, within certain exciting frequency range, in saturated cohesive soils at Gaoqiao District, Shanghai.This paper also reviews factors affecting wave velocity, with computed values of shear wave velocity, dynamic shear and elastic moduli etc.
Abstract：
During earthquake, a high excess pore water pressure may be occurred in saturated sand due to an upward transmitting earthquake ware,which leads to cause loose sand into liquefaction. But there is no any measured data about the developing process of excess pore water pressure during earthquake until now. The authors recorded the developing process of excess pore water pressure around the loose sand by means of vibration from vibroflot at the period of construction and found the excess pore water pressure formed on such condition, as a shallow point vibrating source, consists of two parts fundamentally, pulse pore water pressure and strain pore water pressure. The pulse pore water pressure results from the vibrating P wave transmitted in the pore water and the P wave and S wave transmit outward through the soil skeleton, which produces strain potential on the skeleton of soil. The strain excess pore water pressure is a response of the residual strain potential coupled with the skeleton of soil. The rate between the above two parts are related to the distance from the shake center and to the density of sand. In level surface the field of excess pore water pressure is quite similar to the field of acceleration of ground.They all are the power-functions of distance to the shake center.
During earthquake, a high excess pore water pressure may be occurred in saturated sand due to an upward transmitting earthquake ware,which leads to cause loose sand into liquefaction. But there is no any measured data about the developing process of excess pore water pressure during earthquake until now. The authors recorded the developing process of excess pore water pressure around the loose sand by means of vibration from vibroflot at the period of construction and found the excess pore water pressure formed on such condition, as a shallow point vibrating source, consists of two parts fundamentally, pulse pore water pressure and strain pore water pressure. The pulse pore water pressure results from the vibrating P wave transmitted in the pore water and the P wave and S wave transmit outward through the soil skeleton, which produces strain potential on the skeleton of soil. The strain excess pore water pressure is a response of the residual strain potential coupled with the skeleton of soil. The rate between the above two parts are related to the distance from the shake center and to the density of sand. In level surface the field of excess pore water pressure is quite similar to the field of acceleration of ground.They all are the power-functions of distance to the shake center.
Abstract：
In order to investigate the practical use for evaluating the liquefaction potential of sand with static cone pe'netration, tests were performed at more than one hundred locations of various seismic intensities in Tangshan district. The test results were analysed by statistical method of discrimination founction.In which the effects of the depth of groundwater level, the depth of sand layer, the thickness of cohesive overlaid soil, the epicentral distance and the penetration resistance had been taken into consideration. A simple method was thus given for evaluating the liquefaction potential of sand by static cone penetration tests.The validity of this method has been further confirmed by the test results of Haicheng earthquake area.
In order to investigate the practical use for evaluating the liquefaction potential of sand with static cone pe'netration, tests were performed at more than one hundred locations of various seismic intensities in Tangshan district. The test results were analysed by statistical method of discrimination founction.In which the effects of the depth of groundwater level, the depth of sand layer, the thickness of cohesive overlaid soil, the epicentral distance and the penetration resistance had been taken into consideration. A simple method was thus given for evaluating the liquefaction potential of sand by static cone penetration tests.The validity of this method has been further confirmed by the test results of Haicheng earthquake area.
Abstract：
Using mechanical dynamic triaxial test apparatus and electro-hydraulic dynamic triaxial test apparatus, liquefaction tests of a saturated standard sand were conducted in order to compare the effects of apparatus type, and sample size on dynamic strength. Two groups of test were performed concerning consolidated condition. One was under the condition of isotropic consolidation and the other under the condition of anisotropic consolidition.According to the test results, some points such as apparatus type, failure criteria and dynamic strength parameters of sand are discussed.
Using mechanical dynamic triaxial test apparatus and electro-hydraulic dynamic triaxial test apparatus, liquefaction tests of a saturated standard sand were conducted in order to compare the effects of apparatus type, and sample size on dynamic strength. Two groups of test were performed concerning consolidated condition. One was under the condition of isotropic consolidation and the other under the condition of anisotropic consolidition.According to the test results, some points such as apparatus type, failure criteria and dynamic strength parameters of sand are discussed.
1980, 2(3): 55-63.
Abstract：
This paper presents some important findings found from the researchs on soil liquefaction during the past two decades in the Water Conservancy and Hydroelectric Power Research Institute of China. They are the effect of stress condition on the development of excess pore water pressure in the course of soil liquefaction, the effect of the orientation and arrangement of sand grains upon the stability of the skeleton structure of the sands against vibratory action, the mechanism of development, dissipation and dispersion of pore water pressure in a saturated soil mass commenced by vibratory action, and criteria for evaluating liquefaction potential of silty soils. These topics are receiving more attention now a day in solving the problem of soil liquefaction. The author also tries to deliver his opinion about these problems in this paper.
This paper presents some important findings found from the researchs on soil liquefaction during the past two decades in the Water Conservancy and Hydroelectric Power Research Institute of China. They are the effect of stress condition on the development of excess pore water pressure in the course of soil liquefaction, the effect of the orientation and arrangement of sand grains upon the stability of the skeleton structure of the sands against vibratory action, the mechanism of development, dissipation and dispersion of pore water pressure in a saturated soil mass commenced by vibratory action, and criteria for evaluating liquefaction potential of silty soils. These topics are receiving more attention now a day in solving the problem of soil liquefaction. The author also tries to deliver his opinion about these problems in this paper.
Abstract：
In this paper the indexes of pore water pressure and dynamic strength of saturated sand are carried out under various stress conditions by applying double-action cyclic triaxial test system. These results can be used as a reference in the stabilily analysis of saturated sand foundations and slopes against earth-quake. Moreover, the V-phenomena in the wave peak of the time history of pore water pressure by the characteristic of volume swelling of dense sand under shearing stress are investigated.
In this paper the indexes of pore water pressure and dynamic strength of saturated sand are carried out under various stress conditions by applying double-action cyclic triaxial test system. These results can be used as a reference in the stabilily analysis of saturated sand foundations and slopes against earth-quake. Moreover, the V-phenomena in the wave peak of the time history of pore water pressure by the characteristic of volume swelling of dense sand under shearing stress are investigated.
Abstract：
The phenomena of failure appeared usually for the sand shell of dams and embankments during severe earthquakes.The liquefying test with a dynamic tri-axial apparatus is one of the usual methods to perform.Here, except discussing the drainage and relative density conditions in tests, the decrease of total stress resistance of different sands during liquefaction is presented so as to examine nearly the stability of sand banks.
The phenomena of failure appeared usually for the sand shell of dams and embankments during severe earthquakes.The liquefying test with a dynamic tri-axial apparatus is one of the usual methods to perform.Here, except discussing the drainage and relative density conditions in tests, the decrease of total stress resistance of different sands during liquefaction is presented so as to examine nearly the stability of sand banks.
Abstract：
Simulating earthquake loading conditions, a series of cyclic triazial compression tests was carried out on undisturbed samples of cohesive soils from Tianjin so as to investigate the dynamic shear modulus and damping ratio. It has come to the conclusion that the variation of damping ratio, as well as shear modulus, with strain amplitude can be expressed by an empirical formula. The normalized form of shear modulus vs. strain amplitude will be shown by a single curve, and that of damping ratio vs. strain amplitude by a family of curves or a band zone with shrunk ends. The view-point about the law of damping ratio varying with strain amplitude has been developed. A comparison between the measured values from laboratory test and those based on seismic survey for the elastic modulus has been made, and a reasonable agreement has been obtained. For some of cohesive soil strata in Tianjin, some data available for seismic analyses have been provided.
Simulating earthquake loading conditions, a series of cyclic triazial compression tests was carried out on undisturbed samples of cohesive soils from Tianjin so as to investigate the dynamic shear modulus and damping ratio. It has come to the conclusion that the variation of damping ratio, as well as shear modulus, with strain amplitude can be expressed by an empirical formula. The normalized form of shear modulus vs. strain amplitude will be shown by a single curve, and that of damping ratio vs. strain amplitude by a family of curves or a band zone with shrunk ends. The view-point about the law of damping ratio varying with strain amplitude has been developed. A comparison between the measured values from laboratory test and those based on seismic survey for the elastic modulus has been made, and a reasonable agreement has been obtained. For some of cohesive soil strata in Tianjin, some data available for seismic analyses have been provided.
Abstract：
Based upon experiments and analyses, a quantitative relationship between the skeleton dilatant-consolidatory potentials and the pore pressures of saturated sands during the process of liquefaction has been obtained. Rules governing the variations of the skeleton volumes of isotropic and anisotropic consolidated sands during the process of liquefaction have been suggested. Some opinions relevant to liquefaction of sands have been offered.
Based upon experiments and analyses, a quantitative relationship between the skeleton dilatant-consolidatory potentials and the pore pressures of saturated sands during the process of liquefaction has been obtained. Rules governing the variations of the skeleton volumes of isotropic and anisotropic consolidated sands during the process of liquefaction have been suggested. Some opinions relevant to liquefaction of sands have been offered.
Abstract：
Clayey Silt is a slightly plastic sandy loam the plasticity index（Ip） of which is between 3~10 and its liquefaction occurred in a large area during Tangshan earthquake on July 28, 1976.Formulae with 4 or 5 primary factors for predicting liquefaction potential of clayey silt are presented in this paper. The formulae are derived after analyzing three groups of representative data of clayey silt （involving 126, 166 and 231 points respectively）by using a special computer program prepared by authors.The characteristic of the formulae is associated with a discrimination ratio for liquefaction and non-liquefaction. In addition,they can also be used to choose certain discriminas-tion ratio based on importance of engineering projects.The validity of the formulae is established through checking typical examples from seismic zone with different intensity. A practical application is also mentioned in the end of the paper.
Clayey Silt is a slightly plastic sandy loam the plasticity index（Ip） of which is between 3~10 and its liquefaction occurred in a large area during Tangshan earthquake on July 28, 1976.Formulae with 4 or 5 primary factors for predicting liquefaction potential of clayey silt are presented in this paper. The formulae are derived after analyzing three groups of representative data of clayey silt （involving 126, 166 and 231 points respectively）by using a special computer program prepared by authors.The characteristic of the formulae is associated with a discrimination ratio for liquefaction and non-liquefaction. In addition,they can also be used to choose certain discriminas-tion ratio based on importance of engineering projects.The validity of the formulae is established through checking typical examples from seismic zone with different intensity. A practical application is also mentioned in the end of the paper.
Abstract：
In this paper, the soil conditions of two sites at Tianjing area during Tangshan earthquake are compared and analyzed, to find out the influence of soil behavior on liquefaction and finally to present the method of evaluating liquefaction potential of low plasticity clays. This method will make correction for the numbr of blows of standard penetration test according to clayey content. This corrected value is called equivalent number of blows,in which α = coefficient of correction, its values are taken from the following table,clayey content（%）≤3456789101112coefficient of correc-12.052.302.532.752.943.133.363.483.67tion aThe results of this correction method with equivalent number of blows are satisfactory. Ln addition, the possibility for evaluating the liquefaction potential of low plasticity claps by static cone penetrometer is investigated. It is considered that the results of static cone penetrometer are corrected to equivalent number of blows according to the recommendation in this paper. And then the method of evaluating liquefaction potential is used as before.
In this paper, the soil conditions of two sites at Tianjing area during Tangshan earthquake are compared and analyzed, to find out the influence of soil behavior on liquefaction and finally to present the method of evaluating liquefaction potential of low plasticity clays. This method will make correction for the numbr of blows of standard penetration test according to clayey content. This corrected value is called equivalent number of blows,in which α = coefficient of correction, its values are taken from the following table,clayey content（%）≤3456789101112coefficient of correc-12.052.302.532.752.943.133.363.483.67tion aThe results of this correction method with equivalent number of blows are satisfactory. Ln addition, the possibility for evaluating the liquefaction potential of low plasticity claps by static cone penetrometer is investigated. It is considered that the results of static cone penetrometer are corrected to equivalent number of blows according to the recommendation in this paper. And then the method of evaluating liquefaction potential is used as before.
