Porosity change is a common characteristic of natural soils in fluid-solid interaction problems, which can lead to an obvious change of the soil-water retention curve (SWRC). The influence of porosity on soil water retention phenomena is investigated by a theoretical model and an experimental test in this study. A model expressing the change in suction with porosity and effective saturation is put forward theoretically. The model is based on an idealization of three-phase porous materials, the pore structures of which are homogeneous and isotropic. It accounts for the porosity effect on soil water retention, using four parameters with clear physical meanings. The presented model can obtain the SWRC at any porosity, which will reduce the test number required in characterizing the hydraulic behavior of soil. A laboratory experiment for loamy sand with different porosities is performed. The test results show that suction has a significant variation with changes in porosity and decreases with the increase of porosity. The formulation is verified by both the test data and the literature data for FEBEX bentonite and Boom clay. The very good agreements between measured and predicted results show that the SWRC model is reliable and feasible for various soils.

Based on the multi-phase flow & multi-field coupling theory, this paper adopted the finite element method to calculat e the t emperature distribut ion of Muyubao landslide as the atmospheric temperature changes. Further, it analyzed the influence of atmospheric temperature changes on the slope seepage according to the correlat ion between temperature and viscosity of w at er. The results of calculat ion showed that the effectof atmospheric temperature on temperature of the slope body is limited to the shallow surface; as the depth increases, the influence decreases and the hysteresis increases concurrent ly. The mobilit y of the water is affected by the change of the slope body's temperature and it can change the water permeability in the inner slope. The effectof atmospheric temperature on permeability coefficientof the slope has a nonlinear relationship with depth. The effectof atmospheric temperature on the permeabilit y coefficient declines as the depth increases. Generally, the permeability coefficientof the slope no longer change significantly when the depth is deeper t han The maximum depth of infiltration. The permeability coef-ficientof the slope shows seasonal variation with the atmospheric temperature. The permeability coefficient decreases with the increase of depth when the atmospheric t em perat ure is higher than The soil in summer. In cont rast, the permeabilit y coefficient increases w ith the increase of depth in w int er.

Based on the theory of two-phase (water and gas ) flow , this study presents results from the finite-element analysis of soil rainfall infiltration on different gas permeable conditions ,and analyzes the influence of gas boundary per-meability on the stable infiltration intensity ,pore gas pressure and soil saturation distribution .Gas permeable boundary is one of the essential control conditions in the seepage simulation .A quantitative analysis has been proposed to figure out the impacts of gas permeable boundary on the process of rainfall infiltration ,while a majority of conventional studies focus on qualitative research .The simulation results indicate that there is a highly relevant relationship between stable infiltra-tion intensity and gas permeability on the boundary .The stable infiltration intensity is sensitive when the gas boundary permeability is at a low stage ,and as the gas boundary permeability going up the sensibility of stable infiltration intensity is declined .The equation between stable infiltration intensity and gas boundary permeability is regressed to be logarith-mic .Besides ,during the process of rainfall infiltration the pressure of pore gas soars up and the movement of wetting front slows down with lower gas boundary permeability .

Based on the theory of gas-liquid two-phase flow, the finite element method was used to simulate rainfall infiltration in loam soil with different degrees of saturation to investigate the effects of the initial degree of saturation on rainfall infiltration. Numerical results show that the pore air pressure increases gradually in the initial stage of rainfall infiltration;then, the infiltration rate decreases to a stable value because of the jacking force caused by pore air. The stable infiltration rate is mainly determined by the matrix suction and permeability characteristics of soil, varying with the initial degree of saturation. With the variation of the initial degree of saturation, the infiltration rate reaches its maximum or minimum values. The maximum infiltration rate usually appears in the stage of residual or full saturation, while the minimum infiltration rate occurs in the unsaturated stage, depending on soil unsaturated characteristics. Affected by the matrix suction of soil and the relative permeability of water and air, the infiltration rate gradually decreases with the increase of the degree of saturation at first. When the infiltration rate drops to the minimum, it starts to rise with the increase of the degree of saturation. According to the results of numerical simulation, a formula is proposed for calculation of the relatively stable infiltration rate for different initial degrees of saturation.

混凝土龄期是反映自身硬化程度的指标,通常直接将混凝土强度与龄期对应来实现龄期等效.鉴于传统直接法具有离散性较大和费时费力等缺点,引入电阻率法建立混凝土电阻率与龄期的对应关系,从而实现混凝土龄期等效.该方法与其他龄期等效模型比较结果表明,该等效方法是合理、可行的,且与传统方法相比,具有直接、快速、实时性等特点.研究成果可为混凝土龄期等效研究提供新思路.