Advanced Materials Research Vols. 243-249

Abstract: The mechanical and hydraulic behavior of clay in the excavation damaged zone (EDZ) around underground repository is relevant for the assessment of the safety of geotechnical barriers. By integrating Mohr-Coulomb criterion and damage mechanics considerations, an elasto-plastic damage model is established for clay stone. Based on laboratory and in site investigations, the hydro-mechanical coupled damage model and permeability healing model is developed by the fully coupled hydro-mechanical coupled model, which can predict permeability changes and fractures self-healing in EDZ. Considering the construction of connecting gallery of radioactive waste disposal in deep clay formation in Belgium, a finite element damage model for simulating shield tunneling is proposed. The variations of damage and permeability around the tunnel with time are analyzed in detail. The proposed model is able to effectively depict the main features of hydro-mechanical behaviors of Boom clay.

Abstract: According to the survey and study on geological condition, the genetic mechanism and evolving process of the reservoir landslide were analyzed at first that the landslide experienced two large slides. The first slide occurred in the J_2S² formation, it's a collapse slide with small thickness sliding mass, but made the slope on the back edge of the landslide became steeper, which created the conditions for the second slide. The second slide mainly occurred in the J_2S¹ formation, it's a slide that cut layer of rock stratum, which formed present landside. Then, the influencing factors on the stability of reservoir landslide were analyzed, and finite element models were created to calculate and analyze the stability of reservoir landslide under multiple-factors action. The results shows that the landslide is stable in natural conditions, and the safety factor of landslide decreases after the normal storage of reservoir, which doesn't meet the specification requirements; when considering the sudden drop in reservoir level, rainfall infiltration and other factors, the safety factor of landslide decreases further, reaching the critical stable state, and landslides may be unstable when considering earthquake. Therefore, cutting slope and reducing load were suggested, and the calculations show that the landslide trends toward stable under action of multiple-factors after treatment, which means the research achievement has a great reference value to guide engineering design and construction.

Abstract: As the development of social economy, China's urbanization, industrialization has developed rapidly. However the development of countryside^’s economy is slowly. Because of fewer land and more people, a large number of surplus population in the countryside. In order to seek better opportunities for development, many farmers pour into the city. To seek better living conditions, the farmers who are able to live in the city pour into the city. But the poor farmers began to build a new house in the periphery of the country, because the center houses of village do not suit for living. Population outsourcing formed "hollow village", and the question is more and more serious. This article has analyzed the phenomenon of “Hollow village” and some suggestions for improvement are put forward.

Abstract: The resilience deformation rules laboratory test research of the soft soil in the Wuhan region in the unloading condition is done through modified triaxial compression apparatus .And the result shows:(1)the critical unloading ratios of the soft soil in Wuhan region is 0.28 and 0.91.No matter the unloading amount is, no resilience deformation is produced when the unloading ratio is smaller than 0.28 or larger than 0.91,and the resilience deformation is produced when the unloading ration is between 0.28 and 0.91.(2)The void ratio is related to the initial preloading ,the bigger the preloading, the smaller the void ratio, and the bigger the increasing of the void ratio after unloading; the smaller the initial preloading ,the bigger the void ratio, and the smaller the increasing of the void ratio after unloading.(3)The peak resilience rate is linear to the initial preloading.

Abstract: Hydrologic and engineering geological conditions of underground engineering and mining are highly complex. Geological hazards, especially water inflow or inrush, often occur during constructions. In order to get an insight into flow state evolution laws of water inflow and inrush in karst regions, as well as the influence of tunnel excavation, a numerical simulation method was proposed with COMSOL Multiphysics. Three water flow laws, Darcy’s law, Brinkman equations and incompressible Navier-Stokes equations, are coupled and linked with each other. Water pressure and velocity can be analyzed in the course of excavation, and it can be used for further study of risk control of water inflow and inrush.

Abstract: Based on the analysis to the characteristics of two kinds of rock steady creep curves, the nBurgers model that can describe the uniaxial creep properties of rock is presented. Considering the external influences on rock deformation as instantaneous elastic deterioration defined by the reduction of instantaneous elastic modulus and long-term creep deterioration defined by the reduction of long-term creep modulus, kBurgers model with deterioration is presented too. On this basis, three-dimensional model considering the Poisson’s ratio and Bulk modulus as the constant are established separately, and the relationship between their parameters is obtained. Finally, According to a calculation example, the deterioration evolution of model parameters considering water content changing under the assumption of constant bulk modulus is analyzed. In addition, the deterioration evolution equations of instantaneous elastic and long-term creep under the assumption of constant bulk modulus are obtained. It is verified that conversion relationships of model parameters are reasonable.

Abstract: By use of the microseismic monitoring system, the dynamic response of punched pile construction of bridge pile foundation is studied and discussed for the first time. Wave data of loads acting on the construction is group-collected by means of the microseismic experiment on site. Then the waveform, vibration frequency and energy of testing data are analyzed. On the basis of the results, the weaken rules of vibration acceleration and energy are studied, and the effect of impact energy on the vibration velocity is analyzed. It shows that impact energy attenuates exponentially with the distance from the epicentre. The conclusion establishes the theoretical basis for studying the vibrant characteristic of punched pile construction, and provides valuable reference for engineering practice to take effective measures to reduce construction vibration.

Abstract: In view of the fact that large amounts of tonhaltig phyllite were found along the Shi-Tian expressway line, these soft rocks could not meet the roadbed filling requirements. It was necessary to improve the weathered soft rocks to satisfy the engineering demands. Interior comparative tests research on seven modified methods were carried out such as part in different proportions of cement、sand or stone bits, with soft rock of different water contents being artificial to mix and stir evenly, then unconfined compression strength of the samples at different cement quantity、different curing ages were compared; the optimum water content and and maximum dry density were determined through the compaction test; In addition, the principal effect of CBR value was analyzed. thus the best modified way was defined, the aim was to provide reference of theory and examination for further design and engineering application on weathered rock of expressway roadbed construction.

Abstract: Based on similarity theory, the two geologic mechanics models with different intensity of rock layer is established. The paper introduces the design and process of the experimentation. The correlation between the stability of consequent rock slope and the intensity of rock layer is studied. Results obtained show that deformation and breakage of the consequent slope first take place at joints and crannies near the surface. The bigger the intensity of rock layer is, the steadier the slope is. The water in rock cranny can reduce the shearing strength of the slope and lead to land slide. The deformation and failure mode of the slope with low intensity of rock layer is that rock slide along the weak plane as a whole.

Abstract: Based on numerical simulation of computing Software ANSYS, the curve of arching coefficient variation of pressure arch due to actual mining was analyzed aiming to a special mining face, the law of stress transfer and change in surrounding rock was discussed, and the evolving features and characteristics of pressure arch was obtained. The analysis and discussion show the following facts: Arch body will become thicker and stress in the arch body increases with working face’s driving distance increasing; the morphology of pressure arch transits from ellipsoid with long axis in the vertical direction to ellipsoid with long axis in the horizontal direction along the trend of working face; along the tendency of working face, the morphology of pressure arch is a ellipsoid with long axis in the vertical direction.