Applied Mechanics and Materials Vols. 580-583

Abstract: From the feature of rock micro-unit failure obeys Poisson random distribution, the damage softening statistical constitutive of was established under true triaxial confinement based on D-P criterion, so the impact of the intermediate principal stress on rock deformation and failure was considered in theory, and the actual engineering rock complex stress path evolution was reflected more realistically. Furthermore, according to the geometrical conditions of stress-strain relationship, the theoretical relationship between constitutive model parameters and the stress-strain curve characteristic parameters during the process of rock softening and deforming, which enhance the adaptability of the model. Finally, the rationality of the model verified by the measured data.

Abstract: With the development of computer technology, digital image technology is also to grow rapidly. At present, the image processing has become a popular research field. Segmentation is a very important critical step in image processing tasks, which directly affects the subsequent analysis results. Cluster analysis belongs to the category of unsupervised classification and it is not depended on any prior knowledge of the category, so it usually serves as a basic tool to be used for the initial stage of image segmentation. In this paper, we propose a weighted fuzzy threshold algorithm based on fuzzy relations. This algorithm determines the fuzzy membership function according to the similar relationship between pixels, and emphasizes influence of sharpening features of Gaussian function. The new method overcome the drawbacks of clustering algorithms such as, sensitive to the initial value, need to pre-set number of categories. The numerical results show the effectiveness of the new method.

Abstract: Soft soils are well represented as the foundation of buildings all over the world. Settlements of buildings that are built on soft soils are developing over decades and often uneven. This can cause structural damages to constructions and as consequence unplanned repairs or even collapses of buildings in general. To justify the use of different models of soil mechanics it is necessary to carry out their verification. Verification of the model consists of compliance to the simple laboratory experiments and of the adequacy of the field tests description. And the most important thing is that the results of calculations should be based on comparison between series of field observations. The principal difficulty of comparing calculation results with field observations is that the actual soil deformation is developing over a long time, and most of the calculation methods are aimed to obtain finite values of deformations. Comparison between data of finite deformations and data of field observations is not quite correct, because, as a rule, in-situ (field) observations recorded incomplete development process of deformations but not only the final result of settlement. Therefore, to compare these calculations and observations we should select calculation models that can examine the development of deformations in time. Based on the above, it is interesting to analyze the applicability of the most common engineering methods and calculation models of the soils that underlie different calculation programs used in practice.

Abstract: According to golf’s distribution and occurrence situation of Jinghua Gypsum Mine circumstances in Jingmen city, The golf is divided into general golf, filling golf, then the stability of column and covering layer of the two kinds of golf are analysed. It is shown that: For the general golf, A large range of column is stable within a relatively short period of time in the process of underground mining. it will be unstable for local small column because of it was bore weight of overlying strata. After the column was soaked, its strength will be greatly reduced, and the long term stability of column will not be guarantee. Complementary, the covering layer is basically critical stable state; For the filling golf, A large range of column is stable, and the covering layer is also basically critical stable state. It can promote the control of mining disaster and the protection of ecological environment and similar engineering with a high theoretical and practical value.

Abstract: Salt expansion was the main diseases of the salty foundation. In order to study the deformation regularity and quantitative description of coarse particles saline soil ground in natural condition, a field test was conducted in Dunhuang area. The exploratory well with 7.5 m depth (deeper then annual temperature change layer) was excavated on site, and the data of salt content \water content \ground temperature \salt expansion rate were collected. From the test it was found that : salt expansion mainly decided by salt content, salt content and salt expansion rate have approximately a quadratic function relationship; the minimum salt content could cause soil expansion is 1.5‰; The salt expansion force was strong, and the gravitational stress could not suppress the deformation.

Abstract: On the conditions that assuming vertical ground stress and horizontal ground stress are both principal stress, a calculation model of horizontal ground stress value range with depth change in initial geostress field is built by formula derivation, according to the Generalized Hoek-Brown failure criterion, and the reasonability of the calculation model is verified by the geostress measured value. The results show that, there is a good consistency at the distribution range of horizontal ground stress calculated value and horizontal ground stress measured value, it is proved that the the calculation model is reasonable. The calculation model gives new methods and thinking for evaluation of the initial geostress field.

Abstract: Geotextile have been widely used in the reinforced retaining wall, but it is not easy to measure the deformation of the wall during and after construction. To assess the deformation stability of the reinforced retaining wall, an optical fiber sensor was used in geotextile. Based on the measurement accuracy of strain for the sensor geotextile, an actual geotextile-reinforced retaining wall was studied using the fiber sensor geotextile. The experimental results were compared with the results from a numerical procedure, which employs the Mohr-Coulomb yield criterion and an initial stress method and determines the plastic displacement at collapse represented by the distribution of yield elements. The comparison shows that the numerical results have a good agreement with the corresponding measurement values. The result shows the possibility that the procedure gives the realistic evaluation of long-term deformation of reinforced retaining wall.

Abstract: At coastal beach soft soil area, reclamation projects may have great effect on the deformation of the existing underground pipeline. In this paper, the engineering specification method and the finite element method are used respectively for the pipe deformation calculation of the application of platform on piles to handle such underground pipeline deformation control. The results show that the application of platform on piles can effectively diminish the settlement deformation of the existing underground pipe. Co mparing the two calculation results and the monitoring results, the finite element calculation results are more in line with the actual. By appropriately increasing the width of the platform and the pile spacing, the initial design program can achieve a more optimal solution.

Abstract: Hot dry rock(HDR) provides heat through fracture storage layer. The purpose of research on water temperature change of hot dry rock fracture is to study that whether heat energy can satisfy five months winter heating or not. Research method is establishing model of hot dry rock fractured storage layer by means of numerical simulation software FLUENT according to the rock physical properties in Shenyang region. The depth of drilling is 4000m and the water flow rate is 1cm/s. Research principle is high temperature underground rock transfer heat to medium water in the fracture by coupling. Conclude water temperature change equation every two weeks. The results of the study is that fracture water temperature distribution can be approximated taken as linear distribution. According to the slope K, we can conclude water temperature change formula(3.10), and we can use it to infer fracture water temperature.

Abstract: The creep characteristic of saturated silty clay was studied by triaxial drained creep test through two stress paths of axial loading and lateral lightening. According to test data, some conclusions were submitted. First, the axial creep laws between the two stress paths were consistent on the drainage conditions. Volume strains were much smaller than axial strains. Volume strains presented shear dilatancy along with lightening confining pressure. The silty clay creep coefficient was put forward and its variation law was summarized. The silt soil creep coefficient was closely related to the deviatoric stress level. The two had a linear relationship. The silt soil creep coefficientincreased with deviatoric stress level and had no matter with the confining pressureand loading path.