Advanced Materials Research Vols. 594-597

Abstract: This paper starting with the analysis of weathering actuality of Longmen Grottoes in Luoyang, combined with the result of geological hazard investigation of 3 caverns ( Qianxi temple, HuangPuGong cave and Lu hole ), divides the damage effects of Longmen Grottoes into mechanics effect, chemical effect and biology effect, then analyses the geological condition and the solution to protect caverns, and proposes a geological protection project for this kind of stone cultural relics. So as to this paper can provide reference to the similar stone cultural relics protection works.

Abstract: In order to weaken the loss of erosion damage for highway slope in loess area, the author analyzes the main factors affecting the erosion and puts forward prevention measures by theoretical analysis and field survey. He also analyzes the process of rainfall erosion destruction by model test, and the main influencing factors including catchment area, slope length, slope, soil parameter and vegetation coverage, etc as well as the effects and characteristics. This thesis puts forward prevention suggestions from the aspects of enhancing drainage and improving the slope protection according to the main influencing factors, and analyzes the project example. The research result is of certain guiding significance for the rainfall disaster prevention of highway slope in the loess area.

Abstract: Landslides zoning is an effective method of avoiding losses resulted from landslides in the loess areas. In this paper, the most important factors influencing the loess landslides are analyzed. As the five most important impact factors inducing the landslides，earthquake, water, slope, land use and natural density are selected to build a classification model based on AHP method. We obtained three kinds of landslides zonation maps under seismic motion with different exceedance probabilities. Combined with actual exploration, the zonation of landslides in Tianshui city is consistent with actual situation, which indicates that the classification model and the selected factors are appropriate to the loess landslide zoning.

Abstract: Lots of faults exist in rock mass. Acconding on the course of quantitative analysis of fault complexity in mine and modern civil engineering at present, single fault complexity coefficient represents various geologic facts, and its value is less than the fact. Based on the evaluation of sheer incline area ratio and strike-slip fault area ratio about former research, measure fault complexity take an inclined fault interval multiply by the sum of extension length and ratio of numerical statement area. By geometric analysis of geological objects, this paper put forward geometric model which represents geological facts in truth. The results show that expression educed from the model has no multiplicity, is transpicuous and convenient for popularizing.

Abstract: The properties of unsaturated expansive soil were analyzed, and the shortcomings of present methods which are explored to calculate the active earth pressure of unsaturated expansive soil on the retaining structure were discussed. Based on Coulomb’s earth pressure theory, a calculation formula of active earth pressure of unsaturated expansive soil was proposed taking into account of the swelling pressure parameters according to the condition of static equilibrium of sliding soil. The formula has simple composition and derivation process, is convenient for application, and the example shows that this method is reasonable.

Abstract: This paper uses quadric orthogonal rotating combination design test, obtains the internal friction angle change values under given many times freezing-thawing cycles for the geogrid reinforced clay with different degree of compactions, moisture contents and reinforcement spacings. Through analysis of the test data and mathematical calculation to get the regression equation about the internal friction angle change value related with fillers compaction degree, initial moisture content and reinforcement spacing, and test the conspicuousness about the equation and the influence factors. Applies the equation to calculate the internal friction angle change values in the else test conditions, the results show that the calculated values and the testing data fit well, the equation can be used for initial calculation of the under many times freezing-thawing cycles. The regression equation provides a theoretical reference for the engineering practice of geogrid reinforced clay.

Abstract: Coal mining activity has potential hazards to the safety of the Yuecheng Reservoir Project due to ground subsidence and water seepage. Mohr-Coulomb constitutive model was built and FLAC/FLAC3D program was used for numerical simulation analysis of the ground deformation response with mining of coal, then, displacement characteristics of the roof strata and distribution of overlying stress field were brought out, and the scope of water transmitting fracture zone was calculated.

Abstract: An elasto-plastic total stress finite-element computational model is established in two dimensional space to study pile response due to excavation-induced soil movement on the basis of the general-purpose finite element software ABAQUS. And the soil is assumed to be a uniform normally consolidated clay layer. Influences of various parameters including undrained shear strength of soil, excavation depth, strut stiffness and distance from excavation on pile response are investigated. The results indicate that the excavation-induced soil movement is critical for adjacent piles and increasing the undrained shear strength of soil and distance from excavation face would be helpful to control passive pile responses.

Abstract: Widespread problem in hydraulic fracturing of low-permeability reservoir is difficulty of crack initiation of fracturing, high initiation pressure of fracturing put forward higher requirements of fracturing equipment. Low-permeability reservoir for the study, in the fluid-solid coupling conditions, established a low-permeability reservoir perforation mechanical model of stress, using numerical solution techniques, consider the dynamic effects, we can achieve the stress distribution at different stages: drilling, well cementation, perforation and fracturing in low-permeability reservoir. With rock tensile fracture criterion can determine the initiation location and initiation pressure. The results show that the lower the degree of pollution in perforating hole, the smaller the pressure from the crack initiation as well as the higher the degree of pollution in perforating hole, the larger the pressure from the crack initiation. Orientation, diameter and depth of perforating hole effect on crack initiation and extension are more significant.

Abstract: The tailing pond of Wushan copper mine is located in a valley among the mountains, with kinds of hidden troubles like the overflow of the saturation line, the swamping and piping of partial section, and some local deformation, which appeared on both the starter dam and the tailing embankment in the early stage. To meet the requirement of production, a new tailing pond named No.2 Tailing Pond was built in the downstream of the original No.1tailing pond. At present, in No.1 dam, the part below 37m water level was totally submerged by the water, then the condition of the seepage field will change with the rising water level. For the safety of production and to provide a scientific basis to the management of the tailing dam, an analysis of seepage stability at four different conditions of two sections was carried out based on the field conditions of the dam. Finally, a comparison between the simulated results and the measured results was made, the results show that the existing drainage system is safe and effective, and the seepage deformation of Wushan tailing dam will not happen.