Guangdong Province Key Laboratory of Geological Processes and Mineral Resources

Laboratory of, China

Guangdong Province Key Laboratory of Geological Processes and Mineral Resources

Laboratory of, China

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Song J.,Sun Yat Sen University | Tang L.S.,Guangdong Province Key Laboratory of Geological Processes and Mineral Resources | Xing R.J.,Jiaozuo Yellow River Bureau
Applied Mechanics and Materials | Year: 2013

The pore characteristics of saturated clay sourced from microstructure pictures in Pearl River Delta region of south China is analyzed considering the microstructure in different sample sections. The histogram statistics are compared with each other by pore data in terms of the size, the shape and the arrangement of link status. The repercussions of including the anisotropy ratio law of pore characteristics are focused to study saturated clay. It is found that the analysis considering anisotropy ratio results in consolidation by pore distribution based on saturated clay microstructure. The soil porosity of horizontal section was larger than that of vertical section. Vertical section status induced the directional property, and it would be presented directional probability entropy which is able to calculating the chaos of overall arrangement which is a lower value because of directional property. © (2013) Trans Tech Publications, Switzerland.


Song J.,Sun Yat Sen University | Song J.,Guangdong Province Key Laboratory of Geological Processes and Mineral Resources | Tang L.S.,Sun Yat Sen University | Tang L.S.,Guangdong Province Key Laboratory of Geological Processes and Mineral Resources | And 2 more authors.
Applied Mechanics and Materials | Year: 2013

Base on the microscopic structure is characterized by anisotropy of microstructure that inherent in the process of saturated soft clay with sedimentary primary anisotropy or external force caused by induced anisotropy, biological changes along with the trend of the minimum potential energy. By studying the spindle rotation stress characteristics of the soil of the microscopic distribution, the pore characteristics of saturated clay sourced from microstructure pictures in Pearl River Delta region of south China is analyzed considering the microstructure in different stress conditions. Microstructure distribution of soft clay under conditions of section profiling variation including the anisotropy ratio law of pore characteristics are focused to study saturated clay. It is found that major-minor axis status induced the directional property of saturated soil in the process of consolidation by vacuum preloading. And porosity shapes factors which are small indicate directional property would be probability entropy which is able to calculating the chaos of overall arrangement, and it will be a lower value because of directional property. It is apparently inconsistent with the pore distribution of saturated clay which results from the cut section of different point of angle. And horizontal joint and large pore space constitute one of the saturated clay structure characteristic, which related to difference pressure. © (2013) Trans Tech Publications, Switzerland.


Tang L.S.,Sun Yat Sen University | Tang L.S.,Guangdong Province Key Laboratory of Geological Processes and Mineral Resources | Sang H.T.,Guangdong Province Key Laboratory of Geological Processes and Mineral Resources | Sang H.T.,Sun Yat Sen University | And 3 more authors.
Green Building, Materials and Civil Engineering - Proceedings of the 4th International Conference on GreenBuilding, Materials and Civil Engineering, GBMCE 2014 | Year: 2015

The matrix suction widely used in unsaturated soil theory, not representing the interaction between soil particles, is not in conformity with the effective stress principle of soil. The concept ofintergranular suction is an important theory, of which structure suction is the characterization of tensile stress between soil particle, embodying the structure characteristic of unsaturated soil. Cementation strength, as an important part of variable structure suction, plays a critical role in the structure strength of unsaturated granite residual soil. While maintaining the original structure of soil and water content, the decreasing part of soil strength caused by the removal of cementing material is just the cementation strength because of the lost of the corresponding cementation. On the basis of the thought, 3 groups of soil samples are picked up in the northeast of Guangzhou city, whose basic physical and mechanical properties are tested, and whose grain size composition analysis is carried on by sieving method combined with laser particle size analyzer, then the native of the 3 groups of soil sample is determined. The relationship between cementation strength and relative contents of free iron are obtained through penetration test,direct shear test and cementation content analysis test, then cementation strength corresponding 100% relative contents of free iron is calculated by binomial regression analysing the experimental data, at last calculation formula and theory model of cementation strength for unsaturated granite residual soil is established, where the absolute content of free iron and water content as the dependent and cementation strength as independent variables. The experiment results and research show that the ratio of cementation strength in unsaturated granite residual soil to shear strength is more than half of the overall strength of soil, and the cementation strength having positive correlation with cementation content, has negative correlation with water content, but the impact of cementation content on cementation strength is greater than water content. © 2015 Taylor & Francis Group, London.


Tang L.,Sun Yat Sen University | Tang L.,Guangdong Province Key Laboratory of Geological Processes and Mineral Resources | Lin P.,Sun Yat Sen University | Lin P.,Guangdong Province Key Laboratory of Geological Processes and Mineral Resources | And 4 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2011

Based on the classical Boussinesq analytical solutions, a set defined by stress and strain state of points, when subjected to concentrated load, with varied spatial location in semi-infinite elastic subgrade and constrained by certain conditions, is employed to characterize the stress and strain state of a fixed point in the subgrade during the loading-unloading process induced by a single vehicle load. Dynamics, consequently, is transformed into quasi-statics, and analysis model, which is supposed to be convenient and practical for verifying subgrade dynamic behaviors, is established. Stress state and effective working radius are approached and determined during a loading-unloading process in subgrade. Results indicate: (1) curves of dynamic normal stress differences(σ z-σ x) and (σ z-σ y) are pulse shape, while(σ x-σ y) changes in a twin peak manner; (2) the maximum principal stress σ 1 might whirl abruptly about z axis, and the angle intersected with z axis rotates gradually and continuously by 180°; the orientation of minimum principal stress σ 3 turns in a relatively smooth pattern and its rotation features are less remarkably; while the intermediate principal stress direction alters elusively; (3) effective working radius, which represents the limit of impacts exerted by a single vehicle loads on subgrade, pavement system, is suggested to a length of 10 m, and the influenced area can be considered as a semi-sphere with a radius of 10 m and whose center sited at the point of load. At last, the validity of effective working radius, which is defined by 10 m under one vehicle loading, is specified by in situ monitoring data.


Song J.,Sun Yat Sen University | Song J.,Guangdong Province Key Laboratory of Geological Processes and Mineral Resources | Yue R.,Jiaozuo Yellow River Bureau | Zhang P.,China Communications Construction Company Ltd.
Advanced Materials Research | Year: 2012

The behavior of particle migration on soft soil foundation in Pearl River Delta region is analyzed considering the mesoscopic dynamic with vacuum preloading method. The numerical predictions are compared with the fine particle data in terms of settlements, horizontal displacements and vacuum degree of horizontal preloading. The repercussions of including the displacements law of fine particles are also studied. It is found that the analysis considering displacements law results in consolidation by rose diagram of particle migration, which is related to the consolidation of the vacuum preloading of soft soil foundation in Pearl River Delta region. It is apparently inconsistent with the vacuum preloading of the drainage which results from the fine particles migration, but it is fully justified by the fact that the real soil consolidation coordinates corrected for rose diagram obtained. © (2012) Trans Tech Publications, Switzerland.


Tang L.,Sun Yat Sen University | Sang H.,Sun Yat Sen University | Sang H.,Guangdong Province Key Laboratory of Geological Processes and Mineral Resources | Chen H.,Sun Yat Sen University | And 2 more authors.
Journal of Applied Biomaterials and Functional Materials | Year: 2016

Background: In this paper, the quantification for clay structure is explicitly explained, and the approach and goals of quantification are also discussed. The authors consider that the purpose of the quantification for clay structure is to determine some parameters that can be used to quantitatively characterize the impact of clay structure on the macro-mechanical behaviour. Methods: According to the system theory and the law of energy conservation, a quantification model for the structure characteristics of clay materials is established and three quantitative parameters (i.e., deformation structure potential, strength structure potential and comprehensive structure potential) are proposed. And the corresponding tests are conducted. Results: The experimental results show that these quantitative parameters can accurately reflect the influence of clay structure on the deformation behaviour, strength behaviour and the relative magnitude of structural influence on the above two quantitative parameters, respectively. Conclusions: These quantitative parameters have explicit mechanical meanings, and can be used to characterize the structural influences of clay on its mechanical behaviour. © 2016 The Authors.


Li Z.,Shunde Area Survey Co. | Tang L.,Sun Yat Sen University | Tang L.,GuangDong Province Key Laboratory of Geological Processes and Mineral Resources | Hu Y.,Sun Yat Sen University | And 2 more authors.
Applied Mechanics and Materials | Year: 2011

It is of significance for pile foundation design and construction to predict the penetration depth accurately of the displacement pile under a fixed pressure. A new type cone penetrometer and corresponding exploration methods are developed through increasing weight of the device, enhancing the strength of probing rod and probe, and embedding a new function on measuring the total penetration resistance. Not only applied appropriately to various strata except for pebble bed, functions such as the total penetration resistance determination, soil layer classification and soil compression modulus and dynamic-static friction ratio calculation are also provided. Data of total penetration resistance, static point resistance and side friction are measured with the new type cone penetrometer, a new coefficient of dynamic-static friction ratio is introduced and employed to calculate the dynamic side friction, a new estimation method, with which the influence of dynamic side friction is take into account, on penetration depth evaluation of the displacement pile is established and proposed subsequently. Validity of the new method is verified by means of case study of pile engineering and the results indicate, for its high accuracy, the method proposed is of practice and theoretical significance, as well as valuable for popularization. © (2011) Trans Tech Publications.


Lin P.,Sun Yat Sen University | Lin P.,GuangDong Province Key Laboratory of Geological Processes and Mineral Resources | Tang L.,Sun Yat Sen University | Tang L.,GuangDong Province Key Laboratory of Geological Processes and Mineral Resources | Ding Q.,Sun Yat Sen University
Applied Mechanics and Materials | Year: 2011

On the basis of analyzing the occurring mechanism of pile skin friction, pile-soil relative displacement difference function is introduced, and the differential equation which depicts the relationship between pile skin friction and depth is derived, then the calculating model of pile skin friction with depth is established under considering the displacement-interaction process. Field monitoring data are employed to verify the rationality and validity of the model proposed. Through the established model, influences, exerted by pile-soil relative displacement difference, on the pile skin friction distribution are discussed and divided into three stages: I. stage of linear increase; II. stage of nonlinear increase; III. stage of convergence. Filed testing data comparing and theoretical analysis results indicate that the method proposed can describe the transferring process as well as the distribution law of pile skin friction under taking the pile-soil interaction into account, the parameters related and needed can be easily obtained, and the model suggested in this paper is of value in pile theory and engineering. © (2011) Trans Tech Publications, Switzerland.


Tang L.-S.,Sun Yat Sen University | Tang L.-S.,Guangdong Province Key Laboratory of Geological Processes and Mineral Resources | Lin P.-Y.,Sun Yat Sen University | Lin P.-Y.,Guangdong Province Key Laboratory of Geological Processes and Mineral Resources | And 5 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

In order to analyze the dynamic response characteristics of subgrade soil, based on the theory of the layered visco-elasticity system and the dynamic equation and constitutive equation which employs complex compliance to represent the dynamic stress-strain features, an analytic model for the mechanical behaviors of the subgrade soil subjected to vehicle loads is established by means of the transfer matrix method. The model is validated by the observed data. According to the proposed model and the theory of static mechanics, the distribution rules of dynamic and static stresses with depth are investigated. The influences of vehicle loads, load frequency, loading times, soil depth, soil complex compliance and soil density the values and distribution rules of the vertical dynamic stress in subgrade soil are discussed. Some meaningful conclusions are drawn.


Tang L.,Sun Yat Sen University | Sang H.,Sun Yat Sen University | Sang H.,Guangdong Province Key Laboratory of Geological Processes and Mineral Resources | Jiang L.,Sun Yat Sen University | And 2 more authors.
Earth Sciences Research Journal | Year: 2016

The suction between soil particles is the basis and core problem in the study of unsaturated soil. However, is the suction between soil particles just the matrix suction,which has been widely used since the discipline of unsaturated soil mechanics was established. In fact, the concept of matrix suction is from soil science and reflects the water-absorbing capacity of the soil. Matrix suction characterizes the interaction between soil particles and pore water rather than the interactions between soil particles, which are not in conformity with the principle of the effective stress of soils. The suction of unsaturated soil, in essence, is the intergranular suction composed of absorbed suction and structural suction. In this paper, first, the basic concepts of absorbed suction and structural suction were briefly introduced. Then, with soil mechanics, powder science, crystal chemistry, granular material mechanics and other related disciplines of knowledge for reference, the quantitative calculation formulas were theoretically deduced for the absorbed suction for equal-sized and unequal-sized unsaturated soil particles with arbitrary packing and the variable structural suction for equal-sized unsaturated soil particles with arbitrary packing and unequal-sized unsaturated soil particles with close tetrahedral packing. The factors that influence these equations were discussed. Then, the shear strength theory of unsaturated soil was established based on the theory of intergranular suction through the analysis of the effective stress principle of unsaturated soil. This study demonstrates that the shear strength of unsaturated soil consists of three parts: the effective, cohesive force, the additional strength caused by external loads and the strength caused by intergranular suction. The contribution of the three parts to the shear strength of unsaturated soil depends on the following influence factors: soil type, confining pressure, water content and density. Therefore, these factors must be comprehensively considered when determining the strength of unsaturated soil. © 2016, Universidad Nacional de Colombia. All Rights Reserved.

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