Advanced Materials Research Vols. 594-597

Abstract: This paper analyzed the feasibility of tailings briquetting for filling mining subsidence area based on the actual conditions. In the experiment, the diameter 25mm filling balls were made of slurry of Jinshandian tailings and cement, the cement tailing ratio was 1:4, the concentration of slurry was respectively 68%, 70%, 72%, 75%, and the falling strength, the compressive strength, the powder ratio about the filling balls were tested. The results showed that the falling strength was more than 50 times/A; the compressive strength was 5.23~21.12MPa; the powder ratio was 0.69%~10.52%. The results of the PFC2D numerical simulation showed that the maximum stress among the filling balls was 3.39MPa during the ore drawing process. The stress was lower than the minimum compressive strength of 5.23MPa, and the corresponding powder ratio was less than 8%. It has been concluded that the filling-body is able to meet the requirement of the strength and the powder ratio in the mine filling. The filling-body can be applied to backfilling subsidence area.

Abstract: The stability of the karst area transmission towers pile foundation and engineering deal with the problem, the success or failure related to the electric power system operation, the karst area transmission towers pile foundation stability of the subject, the power sector is currently no in-depth case studies, qualitative analysis has been used method and semi-quantitative analysis of the reliability of the method of evaluation results is restricted, and thus how to seek a more rational analysis method and its application in theory worthy of further exploration. In this paper, numerical simulation conducted in-depth study and exploration of a karst area transmission tower pile stability evaluation, design, construction and operation of the project has a certain reference value, has certain reference significance for similar construction projects.

Abstract: The behavior of single axially loaded large-diameter and super-long bored piles have large difference to single small diameter short piles. The article analyzes the load transfer characteristic of single axially loaded large-diameter and super-long bored piles in deep soft clay in the Yangtze River Delta region. And the hybrid method of finite element analysis of rod structure coupling with the shear displacement method for single pile was utilized to simulating and predicting the single pile performance. It is verified that the settlement calculation hybrid method in this paper is reliable.

Abstract: Torrential or atomized rain is one of the key factors that lead to slope deformation and failure. With rain water infiltration, the pore pressure increases and the matric suction decreases even lose, which lead to the soil shear strength sharply reduced and the slope destabilized. This paper selects the in-situ red clay of the Naji reservoir in Guangxi province as research object and investigates the stress-strain characteristics of undisturbed unsaturated red clay under different matric suction conditions by the triaxial test. The numerical verification of test results is conducted by finite element software ABAQUS, using Duncan-Chang model and Mohr-Coulomb model respectively. Comparing with the Duncan-Chang model, Mohr-Coulomb model can reflect the stress-strain behavior of red clay better. And the slope stability of the project in rainfall condition is analyzed by numerical model, which would offer references for the implementation of the revetment engineering.

Abstract: Based on a one-dimensional thermal consolidation formulation with and without thermo-mechanical coupling of saturated porous medium, problems of one-dimensional thermal consolidation of saturated soil were investigated. For the condition with instantaneous constant surface temperature and uniform initial pore-pressure, analytical solutions of excess pore-water pressure and temperature increment were derived respectively by the method of finite Fourier transform and inverse transform. A relevant computer program was developed, and the excess pore-water pressure was compared in detail. The results show that the thermo-mechanical coupling item in the thermal consolidation equation can be ignored.

Abstract: Combined with the research of the stability grade of surrounding rock, this paper put forward into the extension method on surrounding rock stability around underground engineerings with extension theory. The extension method was improved the value of the limited field, the correlation function and weights coefficients to establish the stability evaluation method. The method was successfully applied into the underground engineering case, which has provided scientific reference for design and construction of underground engineerings.

Abstract: The consolidation and conservation of earthen sites is one of the difficult problems at home and abroad. Tianluoshan relic sites is a typical earthen sites located at humid circumstances. For public exhibitions and research purposes, a few chemical grouts were recommended for solidification and conservation of the excavated historical heritage sites. In this paper, the potential application of methyl acrylic acid resin for strengthening Tianluoshan relic soils were evaluated by a series of unconfined compression tests considering the influence of curing condition, curing time, and water content. The results showed that methyl acrylic acid resin can effectively improve the strength of Tianluoshan relic soils.

Abstract: The grey Verhulst nonlinear differential dynamic prediction model is applied to the prediction of the development of rock slope deformation in this paper. And experimental results show that grey Verhulst model is feasible to predict the slope rock mass deformation.

Abstract: The shaking table test on liquefied soil - structure interaction was desighed. In the test, the building model and the soil were evenly arranged, after being put horizontal sine wave acceleration time history, building symmetrical basal dynamic stress, pore water pressure and earthquake-induced settlement time history were obtained. The results are: (1) symmetrical basal vertical dynamic stress, pore water pressure, earthquake-induced settlement reaction time history appeared antisymmetric distribution; (2) basal dynamic stress is controlled by the input waveform, the basal vertical dynamic stress plays a decisive role in the increase of the pore water pressure, while difference of pore water pressure decides difference of earthquake-induced settlement, which causes the building tilts toward the direction of higher pore water pressure; (3) a correlation exists among input wave, basal vertical dynamic stress, pore water pressure and structural earthquake-induced settlement. The mechanism of earthquake-induced settlement is: acceleration waveform  form of both sides basal dynamic stress cumulative form of both sides basal pore pressure form of earthquake-induced settlement.

Abstract: Collapse is one of the major geological disasters all over the world and threats to life and property safety of people. To make a better understanding of the reason it occurs and how to deal with it, the Kim-Yun-Mine collapse is researched. There are one dangerous rock mass and two collapse accumulation body. The basic characteristics of the collapse is described clearly according to the geological exploration data, and the stability of the dangerous rock mass and the collapse accumulated body is analyzed in the way of engineering geology and stereographic projection. At last, we put forward comprehensive control measures based on the results of stability analysis and collapse characteristics.