Applied Mechanics and Materials Vols. 204-208

Abstract: Based on the research of interlayer-gliding structures in Panbei and Panji No.1 coal mine that are located in the each wing of Panji anticline, the Panji mining area is divided into 9 main interlayer-gliding areas and 29 sub-regions. The results indicate that the interlayer-gliding structures mainly developed in the anticline wings, which show obvious symmetry at the type and distribution. The types of the interlayer-gliding structures are fault-sliding and corrugation type in the wings and fracture type in the core area. The type and manifestation of the interlayer-gliding structures also show symmetry in the similar depth. From up to down, the interlayer-gliding type show obvious regularity that fracture type is mainly developed in the shallow area, down is fault-sliding type and corrugation type is mainly developed in the deep or the interchange of the faults. Take fuzzy comprehensive evaluation method to evaluate the inter-gliding structure in west area of Panji No.1 coal mine. The results showed that the results from using fuzzy comprehensive assessment were similar with the results exposed by coal mine. Good effects were obtained for predicting the development intensity of the seam-gliding structure in deep unmined areas in combination with geological conditions of coal mine, providing references for production arrangement of coal mine.

Abstract: Wuchang railway station expansion project was of a urgent construction period, requiring the high level of environmental protection and good quality. And to so large number of foundation engineering, the application of rotary drilling pile construction method could save time, reduce environmental pollution, and was suitable for silt, clay, sand and gravel strata. Through the engineering examples, the construction produces including scheme and technologies are introduced, and production and installation of steel casing, slurry pools and production, borehole-creating, production and hoisting of cages, concrete grouting and inspection key points are discussed in detail. The practice shows that rotary drilling pile construction method has a good overall efficiency in the expansion project of railway station.

Abstract: Based on general instantaneous strength test and uniaxial creep tests under devastating or integrated states, strain characteristics of mudstone in different stages have been determined. Analyzing strain features of mudstone developing in every stage of different tests, evolving creep law of mudstone under uniaxial devastating state may be validated, which axial limited creep strain under the decided loading standard is equal to that value at uniaxial complete strain-stress curve rearwards ultimate strength. Relationship between designed loading stress and its corresponding creep strain can be linear in uniaxial creep test of mudstone under integrated state, while must not be a determinate secant of uniaxial complete strain-stress curve. Studying results present that terminal creep strain of rock with certain loading levels and under devastating state can be only corresponded with an exclusive point of traditional uniaxial complete strain-stress curve rearwards the ultimate strength, and the extended limited creep courses of mudstone will answer for Boltzmann function.

Abstract: Compression and collapse of unsaturated compacted loess are studied by using dry density and water content which easily controlled in engineering, the controlling range of dry density and water content are confirmed respectively. Then the deformation of compression and collapse and the frequency of engineering damager occurrence can be decreased. In addition, the mechanical characteristics of loess in different directions may differ because the loess was consolidated only under the condition of its upper weight of soil and load. The conventional mechanical experiments, including one-dimensional compress and collapse test, were conducted with the specimen of loess soil in different angle from the original horizontal plane. The test result shows that the loess is anisotropic

Abstract: The advantages and disadvantages of two construction methods of steel sheet piles cofferdam are introduced and analyzed in the presented work, the analysis result of three representative models indicate that support setting plays an important role and has a strong influence on the internal force of steel sheet piles. Using genetic algorithm (GA) and matlab finite element and user-defined objective functions, two optimization models are proposed for traditional and inverse construction method. The work of this paper demonstrates that using reasonable support space can effective reduce the maximum bending moment of the steel sheet piles, it means that steel sheet piles can break current water depth limitation and application in deep-sea construction.

Abstract: Consolidation in soil mechanics is the process that the soil to produce compressive deformation under load, and pore volume is smaller, pore water is squeezed out, the soil volume is gradually reduced and finally become stable. In the pit dewatering Project, due to the pore water is expelled, the soil effective stress increases, the pore volume decreases, and the soil produce compression within the influence of precipitation. In this paper, based on the analysis of classical consolidation theory, the differences of two classical consolidation theory is compared, the consolidation characteristics of soil is obtained in the process of pit dewatering.

Abstract: Swelling tests of remolded expansive soil with water immersing are carried out by use of the simple consolidometers. The swelling characteristics of the expansive soil under the different initial conditions are studied. The Dose Response model is used to fit the rules of swelling time interval for expansive soil with water immersing. The quantitative relationship among the swelling and initial overburden pressure, initial water content and initial dry density is attained by use of the three dimensional regression analyses. The important index obtained could be provided to the engineering design, construction and stability evaluation of expansive soil slopes.

Abstract: One-dimensional self-organizing maps neural network (SOM) is used in pile samples selection, and the outcome can improve the accuracy of back-propagation neural network (BP) is proved. Firstly, 71 pile samples are divided into 5 groups according to SOM node weights. Each group is divided into training set, testing set, validation set to build 5 independent BP networks, called BP2. Secondly, 5 groups training set are merged into a new training set, similarly, a new test set and validation set to build another BP network, called BP1. At last, comparison of the performance of BP1 and BP2 show that using SOM network to select pile samples can build a BP network with better performance.

Abstract: The cracking and propagation regulations of compressive-shear rock cracks and the evolution regulations of the stress intensity factor at the branch crack tip under the grouting pressure were discussed in this article. The fracture failure mechanism of rock bridge in the compressive-shear stress state under the effect of grouting pressure was also studied and a fracture failure criterion was put forward. The fracture failure criterion was applied to a example and some useful conclusions were drawn. The grouted pressure and the lateral stress are the key factors which remarkably effect the stress intensity factor KI at the branch crack tip when the certain axial stress and friction coefficient is known. The larger grouting pressure and the smaller value of the lateral stress result in the larger the initial stress intensity factor KI at the branch crack cusp.Under the certain stress and friction coefficient, the higher grouted pressure and lateral tension stress together is easier to lead to crack transfixation. A new way was offered which studied the fracture transfixation of fractured rock mass in the interaction of grouting pressure field and stress field.