Advances in Civil Engineering, ICCET 2011

Volumes 90-93

doi: 10.4028/www.scientific.net/AMM.90-93

Paper Title Page

Authors: Yu Cheng Zhang, Guang Hua Yang, Hai Ying Hu, Peng Liu
Abstract: When strength reduction method is used for side slope analysis, only the intensive parameters are reduced and deformation parameters are not. The ideal elastoplastic model is adopted, and the safety factor is basically in agreement with that of the traditional limit equilibrium method. Main result is the safety factor of side slope, but non-linearity of soil is not considered actually during calculation, so it's hard to arrive at a real deformation field. Based on the deformation modulus elastoplasticity strength reduction method, research of this paper can achieve a more truthful deformation field. Considering the deficiencies in the current slip surface search techniques, this paper mainly studies how to determine the slip surface directly through the slope deformation field and stress field based on the analysis to their characteristics and the formation mechanism and characteristics of slip surface. Three methods to determine the slip surface are worked out: One is to use displacement gradient to identify the most disadvantageous slip surface; The second one is to determine the slip surface using the characteristics of FLAC calculation method and the characteristic that nodal velocity at non-slip area is near to zero and nodal velocity at slip area is very great; The last one is to use the deviation survey method in slope monitoring to track the nodal displacement in numerical analysis, and take the points with displacement catastrophe as those on the slip surface, and link those points to form a curve and finally get the critical slip surface. Analysis is made to the slip surface of clay slope with weak layer. Position of slip surface determined through these three methods is basically the same. Compared with traditional critical equilibrium method, these three methods can not only be applied to homogeneous side slope, but also be used to determine the slip surface of heterogeneous side slope. This paper makes a research on expansion of the application field of deformation modulus elastoplasticity strength reduction method.
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Authors: Jian Ping Sun, Li Lei Zou, Huan Wei Wei
Abstract: Analysis interaction between mini piles and vertical slope under the action of overload, discusses the influence on mini pile and slope under different condition such as pile length,pile diameter and so on. The results showed that: (1)with the micro-pile length increases, bending moment of pile increase present a trend of increase, pile lateral displacement and the displacement of the slope decreases; (2)with the increase in diameter of micro-pile, bending moment increases, the lateral displacement of pile decreases, the slope of the displacement decreases; (3)with pre axial force of soil nails increase, bending moment of pile decreases, the lateral displacement of the pile decreases, the slope of the displacement decreases.
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Authors: Wen Hui Zhang, Yao Ting Zhang, Guo Qing Li
Abstract: In this paper, an evolutionary structural optimization (ESO) method based on the Ishai stress and artificial material elements was used to optimize the structure topology of the cantilever construction of an actual continuous rigid-frame bridge with a new fasting structual system. In iteration process, the engineering infeasible solution was dealt with the engineering constraints; the checkboard problem was solved with the filter scheme, which used the average Ishai stress of the elements located inside the filter domain instead of that located at the center; moreover, the local stress concentration problem was also solved with the scheme of gradully decreasing the filter radius. Thus the iteration ran smoothly, then the optimizing results were obtained finally. The final topology model illustrates the feasibility of the fasting structual system, and the proposed methods are effective to the optimization design for the actual bridge.
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Authors: Xiao Hu, Yong Tao Gao
Abstract: Abstract. As the concrete filled steel tubular has a higher loading capacity, smaller section, stronger rigidity, better deformation and capacity of absorbing energy, besides of its easier construction without formworks, it has a perfect perspective of landslide treatment engineering, while served for anti-slide pile. This paper introduced concrete filled steel tubular briefly, focused on computing formulas of loading capacity and rigidity, and provides references to design of in landslide treatment.
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Authors: Mohamed A. Shahin, Alice Cargeeg
Abstract: The procedure for conventional triaxial compression (CTC) test requires three separate soil specimens to be examined to failure under different confining pressures so that Mohr-Coulomb (or stress path) failure envelope can be determined and soil shear strength parameters can be obtained. An alternative procedure is the multi-stage triaxial (MST) compression test, which requires only one soil specimen to be tested at three stages of shearing with different confining pressures. There are several advantages for using MST over CTC, which apart from fewer soil specimens, include less laboratory time consumption and reduced effects of heterogeneity among the specimens tested. However, it has been argued in the literature that the advantages of using MST may be compromised by its inability to obtain reliable soil behavior or accurate shear strength parameters. In this paper, the accuracy of MST compared to CTC is investigated for a c-phi soil, and a simple procedure that can be adopted to rectify the MST results is proposed.
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Authors: Zhang Xuan Ning
Abstract: Aiming at the problem of the isolated coal pillar occurring the rock burst easily and having no the occurrence and damage theory of the rock burst according with actual, it discusses the generation mechanism of tension rock burst of the isolated coal pillar, uses finite element software of the tension fracture to simulate the fracture and evolution process on the function of the triangle load of the isolated coal pillar. The result shows that the coal pillar generates tension fracture on its both sides, the fracture direction is horizontal. After the coal pillar cracks, the stress is released, forms new stress concentration and the loose region. The coal pillar generate to slide on the horizontal direction on the interaction of the coal pillar and the top and bottom roof and on the function of the geological. This can provided the theory basis for the prediction and forecast of the rock burst of the isolated coal pillar.
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Authors: Lu Bo Meng, Tian Bin Li, Zheng Duan
Abstract: To investigate the transient electromagnetic method of response characteristics in the tunnel geological prediction, the finite element numerical simulation of unfavorable geological body of different location, different resistivity sizes, different shapes, and different volume size were carried out by ANSYS finite element software. The results show that secondary electromagnetic field of different location of unfavorable geological body have same decay rate, when detection distance from 30m to 70m, transient electromagnetic responses are strongest, followed distance from 10m to 30m and from 70m to 90m. The shape, volume and resistivity of unfavorable geological body have strong influence on transient electromagnetic response, unfavorable geological body more sleek, the greater the volume and the smaller the resistivity of unfavorable geological body, the secondary electromagnetic field decay slower.
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Authors: Hong Liang, Yan Wang, Tian Ping Zhou, Zhen Tao Zhang, Zhi Gang Li, Jin Fang Zhao, Te Rigele
Abstract: Abstract. Silt in some areas of our country is very extensive, its distribution is different from the cohesive soil, or sand soil, has unique engineering characteristic. Silt regional characteristics make it has many unique physic-mechanical performance. This article take the G209 (Inner Mongolia Helin to Qingshuihe section) the roadbed silty soil as the study object, study its basic physics, the mechanical properties as well as the distortion and the intensity change rule under the dry-wet circulation, do a comprehensive and systematic analysis about varieties of basic engineering characteristic of the silt in the region Through the condition of dry-wet circulation of unconsolidated tri-axial tests, this article study the silt sample failure pattern under different degree of compaction, stress-strain relations and the change rule of strength. The test results show that: as cycle index less and confining pressure down, test sample is basically brittle failure, on the contrary case, it is behaved for plastic failure and stress-strain curve is close to sclerosis type; When cycle index increase gradually, the cohesion of silt reduced significantly ,with the increase of dry-wet circulation times internal friction angle is on the trend of the attenuation oscillation ; On this basis, we build the relationship expression of shear strength parameters cohesion internal friction angle and dry-wet circulation times.
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Authors: Jian Ping Pan, Sheng Yi Wang, Shui Tai Xu
Abstract: Tailings dam due to earthquake action may lead to severe slippage damage, and setting antiseismic measure is an effective method to prevent damage. Dynamic nonlinear finite element method is used in the efforts to analyze the earthquake reaction and the deformation characteristic. To reduce dam seismic deformation, the reinforcement effect of geotextiles, rock pressure and stone column is studied. Finally, a synthetically antiseismic measure that is composed of geotextiles-reinforced in sub-dam, rock pressure out of starter dam and densification foundation is proposed. It is found that the synthetically antiseismic measure produces better antiseismic effect, and offers a consult for the antiseismic design of tailings dam.
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