Advanced Materials Research Vols. 368-373

Abstract: In China subgrade engineering practice, for embankment settlements, there were often greatly different between calculated values and the measured values. The discrepancy of actual vertical stresses distribution and calculation vertical stresses distribution under embankment may result the difference. The vertical stresses distribution under some embankments were measured, and which were compared with the vertical stresses calculated by three different methods. The differences and relationships among the four kinds of vertical stresses was analyzed. The applicable conditions of the various calculation methods were put forward.

Abstract: EPS composite soil is a new kind of lightweight soil. As the fill material for the embankment, it has enormous advantages. Based on a known case, a finite element model was established, and its efficiency and rationality were verified. The established model was used to analyze the mechanical behaviors of the embankment considering EPS composite soil and the conventional soil. It was concluded that EPS composite soil can effectively reduce the settlement, soil pressure and excess pore water pressure and so as to improve the safety of the ground. It will have widespread applications.

Abstract: Due to the subjectivity and limitation for estimating the disturbance factor in the Hoek–Brown formulas, this paper proposes the term "the generalized disturbance factor" and points out that this term is more appropriate in describing the degree of disturbance of the Hoek–Brown rock mass. The longitudinal wave velocity is selected to quantify the generalized disturbance factor. The feasibility of the recommended method is examined in this paper by use of the basic data and in-situ testing results of a project.

Abstract: Under the control of the tow-Yun fracture, the geological conditions are complicated and the rock strata is broken in Shiyan area ,in the northwest of Hubei province, and the rock mass is weathered into fragment. When Highway is built in this area, a lot of tunnel portal slope and landslide problems will be met. To properly solve these problems, it is needed to analyze the slope stability and to propose appropriate management measures. In the paper, taken a highway tunnel portal slope in Shiyan area for example, a detailed research was made on the mechanism of landslide formation, and using laboratory soil test results and the simple Janbu method, the local and global slope stability is calculated. The results show that the slope is stable in natural state, and in heavy rains the stability coefficient is reduced quickly and the slope will be sliding. So the slope needs to manage and the rain water needs to control.

Abstract: The reliability analysis in this paper is implemented directly starting from the basic variables of the HoekBrown criterion. A limit state equation, in which the basic variables of the HoekBrown criterion are contained, is built by introducing the factor of safety of slope. The calculation procedures of three methods used in the reliability analysis of this paper are analyzed in detail. The stability analysis for a cut slope shows that the reliability results obtained by three methods have little differences. This paper also suggests a simple and fast method for estimating the reliability of slope stability.

Abstract: Explicit equations of stress, displacement and pore-water pressure are derived by solving Biot’s consolidation equations through Laplace and Hankel transforms. A numetical analysis is developed on the semi-infinite viscoelastic body with Burgers model. Reasonable results show that the present theory is correct and with high accuracy and efficiency.

Abstract: Cast-in-place pile with its strong adaptability, cost moderate, construction simple and its high bearing capacity, can penetrate through the soft soil layer, facilitate underwater construction and the settlement is small and other characteristics are widely used in bridge engineering field. But the changeful gulf climate, tidal fluctuations bring a lot of inconvenience to bridge foundation construction, and sea water features affect the durability of the bridge foundation, so cast-in place pile foundation construction are difficult technical at gulf environment. This paper introduces a successful practice about cast-in-place pile engineering in the bay bridge. Combined with the Fanhe Harbor Bridge engineering practice, based on the special hydrological, geological conditions, this paper expounds the gulf cast-in-place pile construction and key technology.

Abstract: Ningde nuclear power plant in Fujian province is one of the national key construction projects of nuclear power, in order to insure the smooth progress of construction project, it needs to assess the rock slope stability which lies in the southeast of the living area. On the base of the rock architectural feature, the qualitative analysis, the three-dimensional limit equilibrium and the three-dimensional finite element are adopted to analyze the stability of the slope. The result of the qualitative analysis shows that most of the slope is stable, and part of it may fail after excavation. The result of the three-dimensional limit equilibrium and the three-dimensional finite element both illustrate that the slope is stable after excavation with slope ratio 1:0.25,1:0.50 and 1:0.75, and the stability factor rises with the decreasing of the slope ratio. At last, according to the above computing result, the 1:0.50 or the minor value is suggested to be adopted as the design slope ratio to excavate the slope.

Abstract: Dissolution of gas and salts leads to the variation of groundwater property in geotechnical medium. By thermodynamic calculation the effect of the pH value of groundwater on chemical grouting is discussed. The effect is shown mainly in two aspects: one is gelling time of chemical grout, the other is the durability of products. At the same time some ionic species in groundwater may react with grout to precipitate, which affects chemical grouting.

Abstract: It has been proved by the seismologic observation of 5.12 Wenchuan Earthquake that a large number of shallow-buried depth mountain tunnels at the portal are underwent severe damage. Earthquake waves, especially Rayleigh waves may be a major factor causing the damage. The numerical model of the shallow-buried depth mountain tunnels by FLAC3D is establishes in this paper, and the dynamic responses of the shallow-buried depth mountain tunnels under the action of Rayleigh waves are simulated by loading on normal Rayleigh waves. The effect of different strength of surface waves is simulated by the in-site blasting tests. The dynamic responses of the tunnel lining under the action of Rayleigh waves are obtained by filtering and composition separation in order to discuss the incidence and mechanism of action. The results show that the dynamic responses of tunnel lining under the action of Rayleigh waves mainly focuses on the portal of tunnel, namely the buried depth and lengthways depth of the tunnel are 0~16m and 0~20m, the tunnel lining is damaged easily in the incidence, and the multiplicative effect of Rayleigh waves often occurs at the portal; beyond the incidence, Rayleigh waves attenuate rapidly and the dynamic responses of the tunnel lining decreases gradually, which has little effects on the safety of tunnel structures.