Applied Mechanics and Materials Vols. 405-408

Abstract: This paper has discussed the mechanism of compacted clay and the influence of compaction and penetration effected by different technological parameters such as particle composition and times of compaction etc. This research is important to ensure the quality of construction, accelerate the construction schedule, and provide reference for detection, evaluation and quality control of projects with similar requests.

Abstract: This article introduced the development of the constitutive model of soil briefly, and analysed several classic constitutive models. On this basis, the paper reviewed the development trend of the constitutive model of soil, and expressed the urgency of perfecting the constitutive model of soil, which considered coarse soil particle breakage.

Abstract: The calculation equations of soil-column area replacement ratio (m) recommended by Chinese code Technical Code for Ground Treatment of Buildings (JGJ79-2012) have many limits in the practice. In this document, general equations of m value are derived by subdividing the composite soil element under the different pile arrangements. The results show that m value is determined by the two parameters: interval number among piles (n) and pile diameter-spacing ratio (d/s). m value greatly decreases with the increase of d/s at the constant n, whereas m slightly decreases with the increase of n at the constant d/s, and the larger n, the smaller drop of m value. Under triangular pile arrangement, the Chinese code recommended equations can be used with less than 10 percent of error ratio of m value when the width of composite foundation is above 10 m, but the general equations should be applied when the width is below 10 m. Under square pile arrangement, the recommended equations can be used when the width of composite subgrade is above 15 m, but the general equations should be applied when the width is below 15 m. The general calculation equations of m value derived in this paper can provide certain reference for theoretical calculation and engineering application.

Abstract: Based on FLAC^2d with its built-in fish language, the coupled procedure of the overland runoff and the unsaturated water-gas two phases seepage model has been compiled. On the assumption that the slope surface is impervious, with the analytic solution of the overland runoff, the numerical solution has been investigated and with the example analysis, it is shown that in order to accurately assess the rainfall influence on the slope stability, the coupled boundary and the water-gas two phases flow should be taken into consideration in numerical simulation

Abstract: To solve the designing problem in control the deformation and stability of reinforced retaining wall in the airport, the paper introduced the method of finite element strength reduction. After the determination of the soil constitutive model, the geogrid reinforcement constitutive model and stability calculation parameters, the research established the stability and deformation numerical simulation model of a reinforced retaining wall, and carried out a systematic analysis of the retaining wall by the finite element method, provided a scientific basis in order to ensure slope safety and optimized the retaining wall design.

Abstract: In order to avoid the limitations in traditional methods of basal heave stability analysis for deep foundation pit, numerical analysis was adopted by establishing a two-dimensional elasto-plastic finite element model. Resistant heave stability safety factor was calculated using the fitting formula acquired from the simulated results, and then the upheaval value and plastic range under critical conditions were studied. The results show that the soil stress will be redistributed with the increasing of excavation depth until upheaval damage taken place. The upheaval value will be larger, the plastic range will be greater, and the basal heave stability will be worse with the decreasing of plastic parameters. Meanwhile, the basal upheaval peak position will transform gradually from excavation center to diaphragm neighborhood with the decreasing of plastic parameters. There is a critical value associated with supporting parameters for soil plastic parameters and the possibility of upheaval destruction increases significantly if the plastic parameters are less than the critical value.

Abstract: In this paper,vertical displacement of pile and pile-surrounding soil was assumed as incompatible.Derivation and revision of the formula of relative slip-caused friction force between pile and soil were made.According to the formula in this paper, side friction of pile reduces as as depth increases,until side friction almost reaches zero at pile bottom,which are concordant with site observations.This calculating method reliably reflects the variation law of side friction of pile.

Abstract: On the basis of the dynamic triaxial liquefaction test of the loess samples which were taken from the Shibei tableland, Guyuan city, and evaluating the liquefaction potential of the loess through laboratory experiment and response analysis. Then the liquefaction characteristics of saturated undisturbed loess under different level of liquefaction are analyzed based on the evaluation results. The results are shown that: when the saturated undisturbed loess liquefaction is light, dynamic stress is decayed barely, weak dynamic residual deformation is generated, pore water pressure begins to grow, the dynamic stress dynamic strain stagnant curves have not marked change, and the deformation of the soil is at viscoelastic stage. When the loess liquefaction is middling, attenuation of dynamic stress is not obviously, dynamic strain is increasing, amount of pore water pressure much higher than stage one, the long axis slope of hysteresis curves is reduced significantly, the sizes and shapes difference of adjacent hysteresis loop is obvious, and the deformation of the soil is at viscoelastic-plastic stage. When the loess is liquefied completely, dynamic stress is decayed evidently, dynamic strain increased dramatically, and its crest value could exceed 10%, the peak value of pore water pressure is sustainable increasing, and emerge the apparent fluctuation under the action of a drastic dynamic strain, the form of the stagnant curves tend to be irregular, the loess is in elastic-plastic stage.

Abstract: Based on the experiment of frictional resistance between concrete short pile and lightly weathered silty mudstone, the frictional resistance of concrete short pile on uplift loading was analyzed and the ultimate friction resistance was obtained. Considering the site geotechnical investigation report and relative standards, the safety factor of side friction of uplift bored piles in soft rock was defined according to the testing of frictional resistance between concrete short pile and lightly weathered silty mudstone. Achievements in this research are already applied into engineering practice.

Abstract: Construction of deepwater pile foundation is difficult and complex. By the example of Xiaoyi reservoir bridge, this paper introduces the construction scheme of the pier in the water, which is building temporary bridge and drilling platform. Field-operation platform and steel sheet pile cofferdam. Engineering practice proves that this construction scheme can speed up construction schedule, and can ensure the quality of construction, which offers mirrors and references for similar engineering.