Advanced Materials Research Vols. 838-841

Abstract: Taken into account the effect of pile partially separated from soils, the dynamic stiffness and damping of pile in horizontal vibration is caculated by using the theory of computation about the mixed boundary value problem of circular holes radiation stress at an infinite plane and the theory of elastic waves, and the Fourier expansion method. The calculated results based on this paper are compared with the calculated results of the other literature. It is showed that the calculated results considering the influence of pile-soil separation are less than that of the other literature, which the bonding of the pile to the soil was assumed, and are in good agreement with experiments.

Abstract: A project in Xiamen setting three basement, the surrounding environment is more complex.the depth of the foundation pit is 11.0-16.1m, considering the duration, cost, environment and other factors, different positions of the foundation pit is respectively realized by adoption of double-row piles, pile-anchor retaining, pile-strut bracing structure and other forms of support, excavation practice proved that this composite support effectively support the pit, facilitate the construction, and the cost is relatively low.

Abstract: The dune sands of the coast of Rio Grande do Norte State, northeastern Brazil, have serious engineering problems, namely low bearing capacity for shallow foundations and are not suitable as material for sub-base and road base. The use of this material in engineering practice needs improvement of their geotechnical properties. This paper investigates the effect of adding Portland cement to stabilize dune sand from the region of Natal, Brazil. Undrained triaxial tests were carried out to evaluate the effect of cement content on the geotechnical behaviour of dune sand-cement admixtures. Tests with admixtures with cement contents of 2.5, 5 and 10% of the dry mass of soil were carried out. Results showed that soil cohesion increased with increasing cement content. The friction angle of the admixtures was lower than that of the uncemented sand for cement content of 2.5 and 5% while It was larger than that of the uncemented sand for cement content of 10%.

Abstract: The construction project is located in Beijing personnel concentration areas which is the special geographical position. The height of the surface construction is about 80m. And the foundation cushion bottom elevation in the most area of foundation excavation project, the circumference is more than 700m, belongs to super large deep foundation pit. During the excavation process, the scheme of setting heavy curtain pile between two adjacent reinforced concrete slope protection piles could effectively control groundwater variation, prevent the possibility dangerous condition in advance and ensure construction period. It has an obvious benefit and provides reference meaning to other similar super large deep foundation pit in ground water controlling.

Abstract: Large scale underground caverns are under construction in high in-situ stress field at Houziyan hydropower station. To investigate deformation and damage of surrounding rock mass, a elastoplastic orthotropic damage model capable of describing induced orthotropic damage and post-peak behavior of hard rock is used, together with a effective approach accounting for the presence of weak planes. Then a displacement based back analysis was conducted by using the measured deformation data from extensometers. The computed displacements are in good agreement with the measured ones at most of measurement points, which confirm the validities of constitutive model and numerical simulation model. The result of simulation shows that damage of surrounding rock mass is mainly dominated by the high in-situ stress rather than the weak planes and heavy damage occur at the cavern shoulders and side walls.

Abstract: The stress, strain and stability of slope would be changed if an Electricity transmission tower built on loess slope. In this paper, the distribution of stress, strain characteristic and stability of loess slope in condition of 30 meters height and 45 °slope triggered by action of Electricity transmission tower should be studied, the result shown that stability of loess slope dominated by the initial stress states, elastic modulus, and Poisson's ratio, strength and shape, structure and load condition etc. the stability distance of transmission line tower be located on loess slope governed by the stability of initial slope and the effect range triggered by tower load, in condition of 30 meters height and 45 °loess slope, the stability distance nearly 20m to 25m.

Abstract: To solve large symmetric indefinite linear systems in finite element discretization of 3D Biot's consolidation equations.This paper adopted diagonal preconditioned conjugate gradient method to FE program. Several numerical examples show that the diagonal PCG method are significantly more efficient than direct solution method for large-scale symmetric indefinite linear systems.

Abstract: Rock mass is simplified as homogeneous material. Shear strength reduction approach is applied to evaluate stability of rock slope and calculate safety factor of sliding surface. Mohr-Coulomb fracture criterion is used to evaluate the sliding state of every element of finite element model for rock mass. The shear strength parameters of rock mass are evaluated from the laboratory tests and engineering analogy. The distributions of plastic zone at collapse state and safety factor of sliding surface are determined.

Abstract: Because of the special geological structure, folds are the main place where underground water gathers and moves. When we build roads or tunnels in folds of the western mountain areas, we should consider the effect of underground water on surrounding rocks and on stability of lining of a tunnel. The author explains in system the movement of underground water in anticlines, limbs and synclines, analyzes the physical, chemical and mechanic effects on rocks during its movement, then puts forward the reasonable advices in choosing the location where a tunnel should be built and specifies the stability of a tunnel. Also, in order to solve the water-gushing problem which may occur during the construction, the author brings forward some control measures for reference when selecting tunnel line and constructing.

Abstract: The landslide research has continued for more than 100 years, in order to analyze the relationship between rainfall and landslide, the research methods of the relationship between landslide and two main characteristics of rainfall (rainfall and the rainfall process) which affect the stability of the landslide are summarized and analyzed the basic situation and characteristics of the main research methods. Several current problems about research methods of rainfall landslide were put forward:1) complex conditions apply problem;2) the Response rule of landslide surface moisture;3) the variation of surface the water content in different parts;4) The development and change law of landslide thrust force under the action of rainfall need further inquiry;5) lack of factor analysis of variation characteristics and influence of rainfall conditions the development law of landslide displacement and the displacement of landslide in different parts;6) lack of analysis and research interactions between multiple physical effects. Then suggestions and outlooks were given in response to these issues: the data statistics and numerical calculation as the foundation, combined with the response of landslide physical model experiment of multi physical quantity for a comprehensive analysis of the relationship between rainfall and landslide.