Applied Mechanics and Materials Vol. 577

Abstract: Chishi Bridge is seated on Carboniferous limestone and Carbon limestone in which karst is strongly developed. Based on analysis the characteristics of the construction of bored Pile an geology, a scientific safety assessment system is the established and Fuzzy AHP(Analytic Hierarchy Process) is used to conduct a comprehensive safety assessment. The results are accordant with the actual and good results can be achieved. But in practice same new situation may be meted, the evaluation system suit be improved and supplement constantly to make the system more perfect.

Abstract: With the large-scale application of the prestressed concrete structure, the quality of the concrete component defects and pipeline grouting has increasingly become the focus of attention. The impact-echo scanner uses the nature of wave, which pass though different media at different velocities, to distinguish internal defects of concrete, pipe filling density and so on. In this paper, using the impact-echo method to detect the concrete block with prefabricated defects of shape, location, and size explores the effect of defect properties, parameter settings and detection environment to impact-echo preliminarily and also explores the relationship of pipeline filling status and impact-echo image. Based on this study, the article raised the problem met during this non-destructive testing methods applied to engineering, and accumulated a certain amount of available engineering data. The experiment results show that using the impact-echo method to identify the defects of concrete components and to test the quality of pipeline grouting is a more convenient and effective non-destructive testing method. Especially, with the radar method in the pipeline grouting quality inspection which complement each other to make up for the shortcomings the lightning wave in case of the metal medium total reflection phenomenon, cannot detect metal pipe grouting plumpness.

Abstract: In this paper, we studied the effect of preparation on standard dry density and strength of foamed cement by orthogonal test. The results indicate that the more excellent combination is A₁B₁C₁, namely G1, the standard dry density is 376 kg/m³, the flexural and compressive strengths are 0.43 MPa and 0.8 MPa respectively, and the thermal conductivity is 0.074 W/(m·K), which conforms to the characteristics of light weight and high strength. Fewer Ca (OH)₂ crystals and more C-S-H gel generated in G1 through scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis is the reason for its high strength.

Abstract: Based on the background of foundation pit excavation of a village, the process of excavation is simulated by FLAC^3D .And the calculation and analysis is combined with the engineering practice. The results show that the deformation of foundation pit is mainly composed of ground surface settlement, and the maximum deformation occurred in the middle of the pit wall at the top of the part. The surface subsidence with the ongoing of the excavation, the general surface subsidence trend is rising. When it comes to the foundation pit, when the settlement velocity is very large, the foundation turns to be unstable, which need supporting methods. Flac^3D program applied on the excavation of rock and soil deformation law study is feasible. The result of the study to further relevant basis are provided for the practical engineering and have certain practical application value to the rock and soil deformation in the process of excavation research.

Abstract: The paper analyzed the cause of rockburst, indicating that the risk came from hard and thick strata of roof, folding structure, fault, coal pillar and advance speed. Meanwhile SOS micro-seismic monitoring system and KBD5, KBD7 electromagnetic radiation meter was applied to monitor and measure the bumping danger zone. Corresponding to the unloading blasting and water softening, effectively avoid the occurrence of percussive ground pressure to ensure the safety in production.

Abstract: This paper discusses a tunnel whose entrance region is the main engineering background. Based on tunnel geological exploration report, we make the model. By establishing model and using numerical simulation software SIGMA/W and COMSOL to simulate the distortion in seepage condition, we find as tunnel excavation goes on, the pore water pressure of tunnel changes and it leads to infiltration of water in the tunnel, and the deformation of soil increases. The ground surface may sink if the evacuation goes on without taking actions, which is not safe for the buildings around. In case of this situation, the pore pressure of the tunnel around should be controlled from decreasing too fast. The result from our model is just like the result by monitoring measurement. The result shows the feasibility of software modeling in the prediction of tunnel seepage situation.

Abstract: This paper combines the geological condition of Miaoziwan tunnel and numerical simulation software ANSYS to analyze the displacement and stress condition of surrounding rock before and after the excavation. Furthermore, the stability of overlying rock in the tunnel was studied based on the displacement and stress condition of surrounding rock. The breaking law of overlying rock was studied considering the influencing factors to the stability of surrounding. The study and analysis to the breaking law of overlying rock can be helpful to the improvement of surrounding rock stability control and supporting system. Moreover, the result can be the guidance to the excavation.

Abstract: In order to ensure the construction safety and schedule of Qingping tunnel exit, the paper forecast the geological conditions and abnormal prediction of the two holes in front of Qingping tunnel exit by using TSP, then according to the geological detection image data, combined with geological data and working face surrounding rock geological reveal theinte-rpretation. The results show that, the rocks of the Qingping tunnel exit is crushed, more karst structure is development and part of the underground water is rich, where potential safety hazard as gushing and collapse exists in the construction, should take corresponding measures as soon as possible.

Abstract: On the basis of field investigation, the stability of the slope was calculated by GEO-SLOPE considering several different influence factors. After comparing these calculated safety factors, the reason for the failure slope was found out. Then, combined with the construction process, a comprehensive evaluation was given to this slope about the reason for slope failure. It was put forward the corresponding management measures according to the main reason.

Abstract: Somewhere on the specific geological conditions of surrounding rock, adopt the different method, calculates the thickness of immediate roof in the area, the thickness of immediate roof was got, which to explore the suitable method for formation conditions of pressure control method, good effects have been achieved.