Applied Mechanics and Materials Vols. 405-408

Abstract: This project is aiming at the high water content clay in seasonally frozen ground region, based on the expressway program in Heilongjiang province. By applying laboratory test, field test, field monitoring and theoretical analysis, research has been proposed to understand the deformation law and long-term performance of high water content clay subgrade in freeze-thaw condition. From the comparison test of soil and soil treated with lime, road properties of high water content clay has been found out. It is a very necessary and effective method using lime to treat the high water content clay in subgrade construction. Laboratory freeze-thaw experiments uncover the strength weakening law of soil treated with lime. With theoretical analysis and numerical calculation, the interaction between clayey subgrade and pavement structure layer under effect of vehicle dynamic load is analyzed. According to this result, control standards of subgrade frost heave in seasonally frozen ground region and subgrade resilience modulus in spring have been proposed.

Abstract: Numerical simulation model was established with FLAC3D to calculate the bearing capacity and the settlement of composite foundation with different pile-soil shear modulus. Then the rules of the effect of pile-soil shear modulus upon mixed pile composite foundation have been obtained. The results show that there is a great relationship between the pile-soil shear modulus and the bearing capacity of mixed pile composite foundation. Along with the increase of pile-soil shear modulus, the bearing capacity increase. Also, this paper suggest that the right value of pile-soil shear modulus of mixed pile composite foundation solidified by HEC or HAS consolidator dosing 12%, which can be used for the design of mixed pile composite foundation.

Abstract: A series of drained triaxial compression tests under different conditions were performed to quantitatively study the influence of the initial void ratio and plasticity index on the shear strength of remolded saturated clays. The test results show that both the peak stress friction angle and peak deviatoric stress decrease with increasing initial void ratio and plasticity index of the soil under the same confining pressure; whereas, they increase with increasing confining pressure of the soil under the same initial void ratio and plasticity index. A new synthesized physical parameter λ, which simultaneously represent both the type and the condition of remolded saturated clays, is defined based on the test results in this work. The functional relationships among the parameters φd and peak deviatoric stress in Mohr-Coulomb equation and the parameter λ are established to develop a modified Mohr-Coulomb equation by considering physical properties of soil. In this equation, only two input parameters, i.e., λ and the confine pressure, are needed to predict the shear strength of the soil. In order to check the accuracy of the proposed equation, laboratory tests were conducted to evaluate against the predicted results. The results show that the peak shear strength of remolded saturated clays can be well described by the proposed equation. Key words: shear strength; Mohr-Coulomb equation; remolded saturated clays; initial void ratio; plasticity index.

Abstract: The effects on different rainfall characteristics and soil properties of rainfall splash erosion were studied by using indoor simulated rainfall device and compacted cohesive soil test model, and then the function relation between them was summarized. The results show that, in the single rainfall process, raindrop size and rainfall splash erosion amount have power function relationship, bigger raindrop diameter, greater splash erosion amount. Soil initial water content and slope show parabola relationship with rainfall splash erosion amount. In the individual rainfall process, there is the same effect law as the single rainfall process. In addition, splash erosion law is consistent whether the soil surface crust or not, but when there is no crust, rainfall splash amount is more than that when there is crust, which illustrates crust can reduce rainfall splash erosion in some extent.

Abstract: In recent years, using the hydraulic mud fill to carry out the reclamation construction actions has been an acceptable way to settle the contradiction between the scanty lands with the rapid industrial development in coastal regions. How to improve the ultra-soft foundation made of fresh hydraulic mud fill efficiently has been the crucial issue. This paper presents three reinforcement techniques in reclamation projects, and the applications are briefly introduced.

Abstract: The governing equation was formulated for one-dimensional consolidation of the soil layer induced by time-dependent groundwater drawdown. Using Duhamel's theorem and method of separation of variables, analytical solutions were developed for the problem. Based on the solutions, the consolidation behaviors of the soil layer were studied and the factors influencing the consolidation were investigated. The results show that it is necessary to consider both the changes of total stress and pore water pressure on the boundary. The greater initial time factor T_vc is, the slower the rate of the consolidation is.

Abstract: A continuous deformation measurement system of two dimensional granular materials displacement based on digital image correlation method (DIC) has been build up. Direct shear tests have been performed on standard sand in a special laboratory apparatus with different vertical pressure. Using DIC a pairs of consecutive photographs taken during the tests has enabled fields of displacement velocity and strain to be determined. Assumed the proportional of stress and strain, the direct observation of displacements and principle strains has been possible for a series of force of grains under shear at various stages in the direct shear test.

Abstract: Earth pressure is the main factor for retaining walls stability. To study the distribution regulation of earth pressure in geogrid-reinforced retaining wall, in-situ test has been carried out on an experimental wall and analyzed by finite element method. The numerical result fits well with the test data that prove the reliability, the paper analyze the influence for earth pressure distribution caused by factors of geogrid as: stiffness; length; spacing, and the weight density of filling material.

Abstract: This paper investigates the behavior of a 15-m high multi-anchored bored pile wall built in a dune sand overlying a naturally occurring lateritic soil layer. A parametric study using the finite element method was carried out to model wall deflections and ground movements during construction phases. Deflection results from the numerical simulations were compared to data collected in the field. The maximum horizontal wall deflection shows a non-linear decreasing trend with increasing system stiffness. Embedment length was found to play a secondary role on wall deflections. Predicted horizontal wall deflections after preloading of second and third anchor layers were on average 30% smaller than the corresponding field values.

Abstract: According to the improved 3 scales (0, 1, 2) Analytic Hierarchy Process (E-AHP) and Extenics theory, an evaluation model is built to evaluate the slope stability. The model takes into account nine indexes that affect the slope stability. The classical matter element and extensional matter elemen are established by collectting actural data. And combined with the specific example, this model accurately calculated the stability state of the slope. The results shown that it not only can take advantage of Extenics Matter-Element theory and the correlation function to study the relationship between index and slope stability, but also can avoid the shortcomings of the traditional AHP judgment matrix inconsistent. It is a new model to evaluate the slope stability.