Advanced Materials Research Vols. 919-921

Abstract: The ultimate bearing capacity of prestressed anchorage structure is directly related to the interfacial shear stress distribution characteristics of the inner anchorage section. Firstly, the axial stress distribution characteristics of the inner anchorage section for the geotechnical prestressed anchorage structure under tensile load are further studied by indoor similarity model test, and the corresponding fitting formula is established. Based on this result and the force equilibrium conditions of rod body’s micro-segment, the rod body interfacial shear stress distribution characteristics formula is also derived, which fits well with the results of the indoor model test. The research achievements have important significance for the further study on stress distribution characteristics of the inner anchorage section.

Abstract: The triaxial equipment of GDS with digital image processing technique is used in drained test of sand. The result shows that the end restraint and initial defect have significant effect on mechanical properties of sand sample. End restraint and initial defect of sample both can cause inhomogeneous deformation, then form macroscopic shear band in soil testing and numerical simulation. Shape multiformity and formation mechanism of shear band in normal consolidated soil is analyzed based on Modified Cam-Clay Model under plane strain condition. The result shows that end restraint and initial defect can induce and control the formation and shape of shear band. The impaction of different boundaries and initial defect setting are analyzed.

Abstract: In recent years, the increasing Debris flow has been drawing the geologists' attention for its massive destructive force. At present, the research on the debris flow are mainly based on comprehensive multi-factors evaluation or singlue factor qualitative anlalysis. However, all factors have the impact on the debris flow. At present, the research on the factors that foundamentally affecting the debris flow or its character is quite few. This paper use the method of stepwise discriminant analysis to minimize the correlation and repeatability between factors to ensure the selected factor can be fully represent the character of debris flow. In addition, classification is an important way to illustrate general picture of the debris flow. This paper classified the selected 6 key factors by method of FCM (Fussy C Means) to achieve the transition and evolution from general geological classification to the accurate quantitative analysis. The result of such classification will benefit the debris flow cognition and disaster prevention measures.

Abstract: Plane strain problem is currently prevalent in the loess engineering. However, this problem still using conventional triaxial test method for processing. So the paper conducted the plain strain test, analyze differences in plane strain experiments with conventional triaxial experiments under different moisture content and confining pressure. Research shows two points, the first one is the impact on the strength of the soil is more under moisture content than confining pressure, the other is that the soil strength under the plane strain condition is significantly greater than conventional triaxial conditions. It shows that the results were conservative under the plane strain problem at past. It played a certain role in guiding the engineering.

Abstract: A new soil water characteristic curve (SWCC) experiment contemplating urea concentration is presented in the paper. We focus on the impact of the SWCC considering urea concentration test method for materials selection and introduction, experimental results, and finally, we have conducted some experiments of SWCC and obtained some valuable data which could affect urea concentration. By using linear fitting, an exponential function between water content and suction and urea concentration is established.

Abstract: The test results of shear-wave velocity in engineering are of being importance increasingly, but the the uncertainty of the wave test result has influenced the seismic design throughout. In order to describe this uncertainty accurately , the paper has taken some research on the deep-soft sites seismic response. By using SHAKE 2000 program and entering various types of ground motions, the authors discussed the effect of shear-wave velocity standard deviation of several velocity values in deep-soft site to the ground response spectra and PGA(Peak Ground Acceleration). The results are as followed: the standard deviation of the shear-wave velocities has almost no influence on the acceleration response spectra and the PGA of the site; the varieties of response spectra and PGA under different intensity of earthquake can be nearly ignored. With the increasing number of the shear-wave velocity data, results of the study would be further in-depth and perfection.

Abstract: Due to the characteristics of the physical mechanical properties of soft ground, reasonable foundation treatments are usually necessary before it meets the need of foundation deformation and load requirements. How to choose a reasonable foundation treatment method which has obvious virtues of economical expenditure and shorter construction period is an urgent problem emerging in engineering construction in the Pearl River Delta. While drainage sand well is used widely in soft soil foundation treatment in the Pearl River Delta. In this paper, a simplified calculation method is proposed to calculate the strength of soft soil foundation treated by sand well after drainage consolidation.

Abstract: At present, there are not enough research for the initial collapse pressure and collapsible coefficient of the loess in the country; There are tests for the Jinnan collapsible loess, to study the collapsible coefficient and the initial collapse pressure changes with the depth. The results showed that: When the vertical pressure is 200 kPa , the collapsible coefficient is the largest. The collapsible coefficient decreases with the depth increase. The initial collapse pressure increases with the depth increase.

Abstract: More and more high dams with huge reservoirs have been built in China in recent years. A lot of research work on the causes of cracking in galleries of low concrete dams has been carried out at present, while studies on that of high concrete dams are less with the lack of systematic cognition. Based on that, the research on high concrete dams is conducted in this paper, using the method of finite element simulation. It is proven that self-weight action has more influence on the stress of arch crests of galleries existing in high concrete dams, especially the galleries whose overlying concrete height is relatively high. And surface cracks tend to appear in arch crests of these galleries under gravity. In the end, measures for improvement of the stress of arch crest are put forward, of which the effect of enlarging reinforcement is relatively obvious.

Abstract: Selection of five typical loess in Shanxi Province, the paper adopt the indoor test methods to prepares the different compaction and different moisture content specimens which were used to test CBR value and rebound module, analyzes the impact of compactness and moisture content on the CBR value and resilient modulus and establishes the relationship of CBR and moisture content. The result shows that the level of moisture content has great impact on CBR value and rebound module. The CBR value is maximal under optimum moisture content and maximum degree of compaction condition. The times of compaction have little effect on the improvement of CBR with increasing water content. The relationship of the soaking CBR,resilient modulus and the moisture content shows a certain regularity.Key words: Loess filler;the CBR;resilient modulus;compactness;moisture content;relationship