Papers by Author: Hai Bo Li

Abstract: In order to improve the accuracy of the selection on rock mechanical parameters, the relation between uniaxial compressive strength (UCS) and physical mechanical parameters should be investigated. A great number of physical and mechanical tests on rock in the first-stage of Guangxi Fangchenggang Nuclear Power Plant (GFNPP) are conducted. Mineral identification tests of rocks are conducted, and rocks are divided into two groups (A and B) according to the result of the test. The correlation coefficient between rock UCS and rock physical parameters (porosity, density and P-wave velocity) are calculated by using Pearson’s analytical method. The result shows that the relationship between physical parameters and mechanical parameters of rock is influenced significantly by content of quartz. Regression analysis method is used to explore the relation between UCS and porosity, density, P-wave velocity of rock; combined with the dimensional analysis, the relation between UCS and rock physical parameters was established. Based on normality test and randomness test, the best fitting equation is determined as the empirical equation of UCS. The empirical equation was used to forecast the UCS of rock in the second-stage of GFNPP, comparative results show that the forecasting value and the experimental value are in good agreement.

Abstract: In order to improve the accuracy of the rock mechanical parameters, the correlations among physical and mechanical parameters were investigated. A large number of laboratory testing results curried out on 408 rock specimens including metamorphic rocks, sedimentary rocks and igneous rocks. Through the statistical analysis of the laboratory test data, several regression equations among rock material parameters were established. The research suggests that, in addition to Poisson's ratio, the mechanical parameters (unconfined compressive strength (UCS), elastic Young’s modulus, shear modulus) relate well to physical parameters (porosity, P-wave velocity), and the relationships are mainly described by power and exponential correlations which have good squared regression coefficients. The correlation between elastic Young’s modulus and dynamic elastic modulus was established, as well as the relationship between shear modulus and dynamic shear modulus.

Abstract: Design and construction of pile foundation in seaside zone face the specific geotechnical conditions. The in-situ geotechnical tests need to be conducted. The quality feature of the piles is assessed according to the results of in-situ small strain test, coring test and pile stress test. For different depth of rock and soil stratum and pile bearing layer, the trial pile stress distribution results and follow-up stress and settlement monitoring provide engineering parameters for design and pile-driving.

Abstract: Considering the energy variation, cylindrical P-wave propagation across a linear elastic rock joint is analyzed. Then parametric studies are carried out to investigate the effects of the wave source distance,the joint stiffness and the incident waveforms on wave propagation across a jointed rock mass.

Abstract: Analysis of the vibration characteristics of slope is the basis of dynamic analysis of slope; therefore, it has an important engineering significance. In this paper, ideal joint rock slope was studied by the modal analysis and harmonic response analysis module in the ANSYS software, meanwhile, the section of the model size and the effects of the structural parameters on the vibration characteristics of slope were also discussed. The results show that the stiffness of the structural surface is the key factors that affect the vibration characteristics of slope, and with the stiffness of structural surface increases, the first modal shape of slope was changed from dislocation vibration that along the structural surface to horizontal vibration. Only the first natural frequency can be excited the "resonance" phenomenon in the horizontal direction under the seismic load. Therefore, the joint slope is more easily to be excited "resonance" under earthquake load because of the first natural frequency of joint slope is smaller than homogeneous slope; moreover, this is consistent to the investigation results of Wenchuan Earthquake.

Abstract: Focus on the topography features of V-shaped deep river valley in Ada dam area, the influence of intensively, moderately and slightly weathered stratum as well as the action of river valley erosion on geostress field was considered. Then, the 3-D initial geostress unloading model was established based on the measured geostress data and geological conditions. Combining the finite element numerical method and inversion theory, multiple regression analysis was established between the measured and corresponding calculated results of geostress. Then, the optimal regression coefficient could be derived. In addition, for convenience of comparison, another method was adopted by ignoring the action of river valley erosion. Through the comparison between the computed values by two methods and the measured geostress values respectively, it is found that the computed values by the former method are more close to the measured ones. Therefore, the distribution rule of initial geostress field can be obtained accurately, which provides important reference for design and construction of Ada dam and its diversion tunnel layout.

Abstract: The mechanical properties of rock under high temperature and high geostress are the basic and important information to assess the safety of underground engineering. Based on the environmental conditions of the west route of south-to-north water transfer project in western China, experiments are conducted for a sandstone. The experiments are conducted in stress path of hydrostate, pure shear, and conventional triaxial compression at the temperature of 25°C, 50°C and 70°C. The change of strength and average moduli of the rock with temperatures are studied. By cycle loading and unloading tests, elastic and plastic deformation of the rock are decomposed, it is shown that the plastic deformations of the rock are clearly changed with temperature, while the elastic deformation of the rock seems to be unaffected by the temperature. Moreover, based on the associated plastic flow rule, a constitutive law considering temperature is proposed for the sandstone.

Abstract: The mechanical properties of rock under high temperature, high geostress and high pore pressure are the basic and important information to assess the safety of underground engineering in west China. Based on the environmental conditions of the west route of south-to-north water transfer project in west China, a series of triaxial tests at confining pressures (0 to 60MPa) and temperatures (25°C to 70°C) as well as pore pressure (0 to 10MPa) have been conducted for a sandstone. It is reported that under the temperatures varying from 25°C to 70°C, the strength of the rock increases with the increment of confining pressure, while the deformation modulus of the rock doesn’t change distinctly with the increment of confining pressures. It is also indicated under the temperatures condition in the experiments, when the confining pressure is lower than 40MPa, the strength of the rock increases with the increment of temperature, whereas when the confining pressure is higher than 40MPa, the strength of rock tend to decrease with increment of temperature. It is further shown that the strength decreases with increasing pore pressure, and the decreasing rates tend to decrease with the increment of confining pressures.

Abstract: In order to study the strength and deformation properties of rock joint under different shear velocities, normal stresses and undulation angles, series testes are conducted by a RMT-150C testing machines with artificial concrete rock joint samples in the present paper. Base on the experimental results, it can be found that the peak shear strengths decrease with the increment of shear velocity, and the decreasing rates tend to decrease with the increasing shear velocity. The shear strength of rock joints increase with the increasing undulation angles, and linearly increase with the increment of normal stress. It is also indicated that the shear stiffness increase with the increasing normal stress, undulation angle as well as the shear velocity with a decreasing tendency.

Abstract: The progressive failure process of a layer rock slope under explosions is simulated using two-dimensional Universal Distinct Element Code (UDEC). It is shown that the failure process of the slope can be divided into three phases, the formation and growth of local failure area as well as coalescence of sliding plane. In addition, the displacement components of a critical point of the slope are also suggested to be a progressive process.