Applied Mechanics and Materials Vols. 580-583

Abstract: This paper highlights settlement behaviour of piled raft foundation by 3D finite element analysis through Plaxis 3D Foundation program. The effects of pile number, pile length, pile layout and pile spacing on the behaviour of piled raft foundation were studied. The numerical results show that: Piled raft foundation has much more efficency to reduce settlement than that of traditional raft foundation. The value of vertical defomation decreases as the result of the increase of pile number, pile length, pile spacing and vice versa. Pile layout has significant effect on both value and location of maximum settlement of piled raft foundation.

Abstract: Due to various uncertainties, most of geotechnical parameters are small samples, which causes much trouble when the probability distribution of geotechnical parameter is fitted using traditional distributions. This paper uses stochastic weighted method to improve the small samples of Geotechnical parameters into big samples, thus solving the problems caused by the small samples. Meanwhile, the probability density function of geotechnical parameter is derived based on maximum entropy principle, the advantage of presented method is verified through Kolmogorov-Smirnov Test. Case study shows that the proposed method not only overcomes the dependence of conventional fitting methods on classical probability distributions, but also the fitting more close to the fact because the data come from the big sample improved by geotechnical parameters, which has important engineering significance.

Abstract: The analysis of structural materials, especially the theoretical research, is always a challenge. Starting from the structural characteristics of the material, the theory of full state function about the strength - stiffness - strain that reflects the properties of structural material is established on the basis of the structural state of the material. The full state function is an important method to solve this problem. In order to further analyze the characteristics of the full state function, the full state function, strength theory of the material and the constitutive relation found are first studied. It is found that the full state function can more comprehensively reflect the properties of the structural material. The full state function accommodates the strength theory in the classical elastic-plastic theory. The full constitutive relation of the materials can be derived from the full state function. That is to say, the full state function can unify the strength theory and constitutive relation in the classical theory and can be used for the analysis of the structural materials. The full state function is more than a mere form, because it has explicit physical and mechanical meanings.

Abstract: Take the ground-water lowering of foundation pit project in DA Dongmen subway station in Hefei as an example, introduce a kind of environmental impact appraisal model,using softwareFLAC^3D to imitate the key index--surface subsidence, offers relevant safe bases to construct security monitoring department.

Abstract: According to characteristics and surrounding environments of a deep foundation pit with pile-anchor retaining structure, a monitoring program was developed. The monitoring focused on horizontal displacements of retaining piles, subsidence of soil surrounding foundation pit and settlements of buildings near foundation pit. The results show that the maximum displacements are in middle position of sides and at corners of foundation pit. The horizontal displacements and settlements of pits are efficiently rejected by anchors. The displacements of buildings near foundation pit are affected by many factors, such as the excavation speed and anchor. The displacement exists characteristics of time and spatial effects. The monitoring results provide a reliable basis for the safety construction and rational organization of construction.

Abstract: In the traditional slope engineering, the slope processing mainly emphasizes the strength effect, and ignore the damage to the environment. Along with people are to landscape and strengthening of environmental protection consciousness, the slope protection method of tradition can not satisfy the requirement of people.Use Interaction of plant roots and rock-soil body to reinforcement and anchorage on the slope surface protection and reinforcement, which can meet the design requirement for stability of slope surface and restore the damaged natural ecological environment. This paper set up the relations between the tensile strength of plant root and the root diameter, establish the theoretical calculation model of the interaction between plant roots and soil, and study the strengthening of plant roots to soil.

Abstract: A series of centrifuge model tests has been conduced to examine the behavior of high strength piles composite foundation stability under railway embankment in silt or clay or sand different kind of soils. The high strength composite foundation has a symmetrical plan layout consisting of 3×4, 4×6, and 5×8 piles with a center-to-center spacing of 6 or 4 or 3 times pile width. The piles are under the same height of railway embankment, with the same length, and on the same lying soil layer. The high strength composite foundation stability test results are expressed in terms of soils kinds-pile displacement response of the composite foundation, embankment load experienced by soil between piles and piles in the composite foundation, and bending moment profile along individual pile. It is established that the high strength composite foundation stability efficiency reduces significantly with decreasing of the strength of soil between piles in composite foundation. The tests reveal the shadowing effect phenomenon in which the marginal piles experienced larger laterally and bending moment than that of the central piles. The shadowing effect is most significant for the lead row piles and considerably less significant for subsequent rows of middle piles. The approach adopted by many researchers of taking the average performance of piles in the same row is found to be inappropriate for the middle rows, of piles for composite foundation as the outer piles in the row carrying significantly more laterally load and experience considerably higher bending moment than those of the inner piles.

Abstract: Use two kinds of soil, processes the uniaxial compressive strength test under the condition of pressure and zero pressure freeze, concludes different test results. That is the uniaxial compressive strength of frozen soil under pressure is higher than that without pressure, and laboratory test data as the basis for the design of the temporary support is relatively safe.

Abstract: With the example of pile foundation engineering in the limestone karst fissure reinforcement, discusses the principle of reinforcement of pile foundation in karst area, introduces some construction technology of pile foundation reinforcement, the reinforcement design principles and the reinforcement scheme is briefly discussed, and combined with the engineering practice and put forward a set of safety, economy and reasonable treatment plan, to reinforcement technology promote the karst pile foundation bottom cave, fracture.