Advanced Materials Research Vols. 243-249

Abstract: By theory analysis and field tests, failure model of soil around foundation and ultimate uplift resistance of enlarged bass shallow foundation were analyzed. The results showed that the deformation and failure process of soil around foundation under uplift load undergone three phases: 1) soil upon enlarged base compressed, 2) appearance and extension of plastic zone of soil around foundation, and 3) soil around foundation general shear failure. With the combination of the Limit Equilibrium Method, and Sliding Curve Theory, a simplified theory model to calculate net ultimate uplift resistance of shallow foundation assuming cir failure surface under uplift load was established. Then three examples were calculated by this method and the good agreement between theory calculation solution and experimental results validated the rationality of the model. The study in this paper provided an important theoretical support and brand-new idea on calculation method of uplift capacity of foundation with enlarged base and failure surface characteristics determination of soil around foundation.

Abstract: Considering the various loads combination and durability,pile’s diameter,embedded depth,anchor’s rod, anchorage length need to be strengthened in the permanent supporting foundation engineering.Based on Chengdu Museum foundation project, the influencing factors such as pile’s diameter,embedded depth,anchor’s pretentioned force are discussed.With comparasion of calculated data and monitoring data, this paper generalized influence of pile diameter, embedded depth, anchor pretensioned force on permanent pars mechanics properties.

Abstract: Analysis of the expansion of cylindrical and spherical cavities in soil and rock provides a versatile and accurate geomechanics approach for study of important problems in geotechnical engineering. As the method getting more important, the analysis of non-circular shape cavity is becoming significance. The paper has investigated the cavity wall shape varying characteristic and elasto-plastic distribution of stress of elliptic shape cavity under internal uniform pressure during the expansion period through ABAQUS FEM numerical. It pointed that the elliptic cavity wall will tend to circle shape as the internal uniform pressure increasing. It also gain that the elasto-plastic distribution around the elliptic cavity is bigger than spherical cavity’s and smaller than spherical cavity’s when material and pressure are same . The stress characters and the cavity wall transfiguration result is useful for estimate non-circular shape cavity expansion.

Abstract: The rock mass deformation properties of unloading is very different from loading.The physical and mechanical properties of structural plane can bring a very great influence to rock’s unloading behavior. The lower the strength parameter of joint plane and the greater the angle of joint, the lower the unloading modulus of deformation. The greater the connectivity of joint,the faster the unloading modulus of deformation descend. In any case unloading amount is near linear relation with descend amount of unloading deformation modulus.

Abstract: By using ABAQUS software to conduct numerical simulation and model test of pile-bucket under mono-loading of up-pulling force and horizontal force, then make comparison of both results to testify the accuracy of finite calculation model. Then by numerical simulation to study bearing capacity of pile-bucket foundation under combined loading of up-pull and horizontal force. The result shows the pile-bucket foundation horizontal displacement will increase with the increase of up-pulling force at the limit horizontal load, and the horizontal displacement becomes more obvious as the up-pulling load increasing if providing greater horizontal loading force. Before the up-pulling force reaches the limit, horizontal load will not affect up-pulling displacement; after the up-pulling force reaches the limit, the horizontal load can slightly reduce the up-pulling displacement of pile top. The effect of up-pulling load increase on horizontal displacement is obvious for pile depth in soil at 0~15m, but very tiny for pile body with buried depth over 15m.

Abstract: A series of large scale consolidated drained shear triaxial tests were performed on geotechnical grille reinforced sand-gravel specimens, the aim was to study influence of elongation and strength characteristic of geotechnical grille on initial modulus, peak strength, residual strength, brittleness index, volumetric strain and shear strength of reinforced sand-gravel. The results show that: the elongation of geotechnical grille used in the sand-gravel specimens has great influence on residual strength, brittleness index and cohesion of reinforced sand-gravel, but the initial modulus, peak strength and volumetric strain are affected slightly.

Abstract: For soils, failure occurs with lower deviatoric stress under the same pressure (the first invariant of stress tensor) in TXE compared with the strength of the triaxial compression, which is indicated that the strength of soils strongly depends on the third invariant of stress deviator; Although in the traditional Mohr-Coulomb criterion it can be reflected in difference of strength between triaxial extension and compression under the same pressure, it’s nothing to do with the pressure for the strength ratio between triaxial extension and compression. By TXC and TXE, changes of deviatoric stress and the ratio with the pressure were studied

Abstract: Using the rock mechanics multi-function testing machine named RMT150B, the testing study on rock fatigue life due to different affecting factors under uniaxial compression condition are accomplished. It is the study emphasis that the influence mechanism of rock sample fatigue life due to different stress amplitudes, waveforms and frequencies .It shows that the stress amplitude, waveform and frequency can all remarkably affect the rock fatigue life. The influence essential reason of rock life due to different stress amplitudes and waveforms is the different dissipation of energy. And the influence essential reason of rock life due to different frequencies is the different loading rate of speed.

Abstract: The feasibility of utilizing industrial waste to produce soil stabilizer with high added value is discussed from technical effect, economic benefit and production and management mode. Principle of design of the stabilizer with industrial waste is offered based on the properties of stabilized soil structure formation and its special demand on stabilizer components; the examples of the stabilizer composition are presented, and the performance/cost ratio of the stabilizers are compared with that of cement. Reasonable production and management mode for industrially producing the stabilizer with industrial waste is discussed also. It is suggested that as long as appropriate industrial waste is selected intentionally to meet the special demand on the stabilizer composition needed to form stabilized soil structure, the soil stabilizer with high performance/cost ratio can be obtained. It is advised that the stabilizer should be designed individually according to the properties of the soil to be stabilized, the stabilizer should be produced with the production mode of mixing multi-components and adopt the management pattern of incorporating designing, production and sale.

Abstract: A tentative experiment has been conducted on polymer modified cement concrete now widely used. By filtering through 297 kinds of traces of polymer modified cement concrete samples tentatively mixed, we acquire a proper mix proportion, according to which, a total of 75 groups of 225 polymer modified cement concrete specimens are produced. After further selective preference of these specimens, ultrasonic test is done on the selected ones under different loading conditions. Afterwards, signal processing is accomplished by using wavelet transformation and we preliminarily find a kind of acousto-elastic sensitive concrete material which is comparatively sensitive to stress. This kind of material is produced by mixing epoxy resin, styrene-acrylic emulsion, acrylic emulsion, auxiliaries and iron powder into cement concrete together. The sensitivity of ultrasound and stress of this kind of modified concrete behaves preferably well as follows: at the low stress stage, not only the correlativity curve of ultrasound velocity and stress but also the correlativity curve of weighted spectrum area and stress arises apparently. If this kind of material can be applied to the practical engineering successfully, the acousto-elastic test accuracy of the concrete service stress will be greatly improved.