Advanced Materials Research Vols. 243-249

Abstract: Whether the site of backfilling fly ash was appropriate for engineering geology, and how to use effective means to change the geologic bearing capacity of the site were urgent solving problems. This work took a site of backfilling fly ash in the Beishiwang Village, Yindu District, Anyang City, Henan Province as object of study, detailedly did a complete geologic survey on it, got related data and made its engineering geologic assessment and according to the characteristics and requirements of construction projects, we select the most optimal treatment means of the foundation and adopt the most safe and economic perfusion pile with post-pressure grouting to strengthen this engineering foundation.

Abstract: The Sky Pond landslide dam is located in Muchang valley, a branch of the Yellow River branches. From this point it is about 6Km to the mouth of the valley from where the Yellow River flows 0.8Km downwards to the planned Jishi gorge hydropower station. The Sky Pond landslide dam is actually formed by two landslides from both the left and right bank slopes and completely blocks the seasonal river channel. The volume of the landslide dam is about 14 millions m³ with 2.37 millions m³ water stored in the dammed lake under the condition of perennial mean water level. Because (1) the dam body is large in width and thickness; (2) the dammed lake water is small both in volume and weight compared to the landslide dam; (3) recharge to the dammed lake is basically the same as the discharge every year; and (4) there is a natural spillway in the dam body, the landslide dam is present at least 750 years after its formation. Although landslide dams which have existed for several hundreds to thousands of years are generally considered as stable, there are remains which may fail catastrophically. In order to analyze the stability of the Sky Pond landslide dam and provide justification for the future engineering decisions, this paper describes the engineering geological conditions near the landslide dam and the characteristics of the dam body, and a detailed discussion of the formation mechanism of the landslide. Based on engineering geology investigation, a qualitative assessment of the stability of the dam and an analysis of the probability of dam overtopping and piping is carried out. Limit equilibrium analysis has been used to calculate the stability of the dam slope under various operational conditions. Results of the stability analyses indicate that the Sky Pond landslide dam should remain stable and does not present a potential theat to the planned hydropower station.

Abstract: The geological conditions of high slope is detailed, the main deformation characteristics of high slope are described. Based on the above, it is known that the rock mass unloading-loosing and toppling deformation accompanying the creeping along bedding plane or fault mainly happen in the upper and middle portion of the high slope, especially in the upper portion. These deformations have other features in the middle portion of the slope: the deformed rock mass rarely appears the bending, but exists an obvious weak plane out of which the rock stratum and tensile fissures mostly dip to the inner of the slope, suggesting the deformation mainly is toppling and tensile-cracking; inside of the weak plane the dip direction is opposite to the outside. The deformation of the upper portion is different from the middle one in which there has a lot of tensile fissures which attitudes are variable and the degree of the breaking and loosing is largely higher than the middle portion of the high slope.

Abstract: The deformation and failure mechanisms of tunnels in jointed rock mass with variable orientation and overburden pressures were studied by physical modelling. The deformation and expansion characteristics and regularities of joints and its influence on the stability of tunnels were analyzed. The results shown that the effects of unloading and reactivation of joints, and subsequent shear slip and deformation induced by excavation cause the structural instability of tunnels. The deformation, failure, and instability of surrounding rocks are essentially the continued deformation and repeated failure of joints in varied stress field caused by excavation and overburden pressure. When the dip angle of the joint sets is 75°, the joints have extremely striking influence on the stability of tunnels. In addition, with the increasing of the overburden pressures, the deformation extent and failure rate are sped up prominently due to the rapid increasing of the shear stresses on joint planes.

Abstract: Daduhe River is in western Sichuan Basin which is across the Songpan-Ganzi geosynclinal fold system and the Yangtze para-platform. There are some complex geological backgrounds in this region, such as active new tectonic movements, frequent earthquakes and high seismic intensity. Remote sensing interpretation shows that there are lots of large-scale landslides existing between Huangjinping and Detuo in the upper reaches of Daduhe River. It has been shown by the research that the reason why large-scale landslides happened frequently in this region has a close relationship with its special fault structure, landform and strata distribution. Landslides always develop along the concave bank, free face of mountain or the thin mountain ridge and they all have close connection with fault in different degrees. Although the lithology of this section is constituted by ancient Kangding complex, yet the adverse rock mass discontinuity and free face combination lay a foundation for slope’s deformation and progressive failure. The earthquake force, however, is the key factor triggering landslides.

Abstract: Permeability is one of an important characteristic of rock materials. The connectivity of permeate passageways could be used by probability of threshold permeability for evaluation. In the foundation of micro CT scan figures of rock samples, nonhomogeneous density distribution of inner rock is studied and connectivity rough of rock by threshold permeability program is also calculated. And the results are: the distribution of rock permeate passageways is nonhomogeneity and the probability of rock threshold permeability is also greatly declined, which is determined not only by ratios of nonporous particles but also by space distribution styles of porous medium.

Abstract: Based on geological condition of underground factory building in Hohhot pumped storage power station, research and analysis are taken for the fundamental element which affect initial stress field, 3D finite element model of underground factory building is build for the analysis. Beigin with regrssion analysis, adopt linear elasticity caculation of finite element method to take linear regression analysis, and obtain range of optimized parameters. Adopt homogeneous design to definite various assemblies of optimized parameters at different levels. Obtain training sample by elasto plastic caculation of finite element, train for RBF model in oder to get inverse model of ground stress field. The calculation result shown that: RBF model overcome the disadvantages such as slow calculating speed and overfitting of BP model, and it could obtain distrubution rule of initial stress filed by inverse analysis in a reasonable way.

Abstract: ShangPing ore area locates the anti-connected compound part of the east of east west structure-zone in NanLing and the swelling-zone of new china structure. Region structure belongs to the spinal part of the “mountain” structure in PanGuShan. In the mine area, the structure of buckle and bursting engenders very much and the magma activity is frequent. The geology conditions of becoming ore-deposit are advantageous. This text sets out from history, analyses the conditions of becoming ore-deposit, choices advantageous parts and makes authentic geology evaluation and prospect analysis to the prognostic area in order to guide mine designing and mining better.

Abstract: An in-situ water injection test across Xi’ an ground fissures has been done, in order to simulate the activity of the fissures after water seeps, from October to December, 2005. According to the settlement observed of the bottom of testing pit, it is proven that the surface water seepage speeds the movement of ground fissures. Usually, the soil on the hanging wall of the fissures is more fragmentized than that on the footwall, which is propitious to water seepage. The seepage promotes the interaction between water and soil particles and brings about the differential settlement of two sides of fissures. Therefore, surface water seepage accelerates the activity of the ground fissures.

Abstract: The role of surface water is also the main reason for the formation and development of ground fissures. Five mechanisms were obtained on the formation of ground fissures under the role of surface water in the loess region through theoretical analysis, i.e., fissuring mechanism induced by loess collapsible deformation; that induced by dissolution and suffosion; that induced by water-loss shrinkage; that induced by hydraulic pressure; that induced by humidification and softening. As the role of surface water had certain phased and periodic characteristics, repeated fissuring mechanism of ground fissures was analyzed. Consequently, it could be known that the repeated fissuring of ground fissures under the role of surface water was mainly shown as horizontal openness and closure with little vertical displacement, and fissures were intersected and cross-cut with each other to form a complex network structure.