Advanced Materials Research Vols. 446-449

Abstract: Longmen Grottoes is the world’s cultural heritage, now it is facing with serious weathering problems. The weathering problems of Longmen Grottoes are divided into three categories: physical weathering, chemical weathering and biological weathering. With the continuous deterioration of environmental and climatic conditions, the damage of chemical weathering to Longmen Grottoes becomes more and more obvious. The damage and damage mechanisms of three categories of weathering to Longmen Grottoes are discussed based on the previous studies.

Abstract: In order to analysis post-cast concrete strip influence to the pile-raft foundation, it has been taken to developed C++ program that is Poulos displacement solution calculating pile-soil stiffness and thick plank theory analyzing raft stiffness. Taking a frame and shear wall structure for example, it has been calculated to pile-raft foundation whether setting up post-cast strip or not that is foundation settlement, moment and so on. Results indicate that post-cast concrete strip is minutely influence to the pile foundation displacement and moment and not the control factor to this kind of pile foundation’s design. It gives some good references to similar structure analysis and can instruct this kind of pile-raft foundation design and construction

Abstract: Based on cusp catastrophe characteristics of water inrush from floor, a cusp catastrophic mechanical model of a key stratum of floor is established by catastrophe theory. By the model, the paper analyzes mechanical mechanism of water inrush from key stratum of floor with the cusp catastrophic theory. Using an engineering example, the numerical simulation proves that this method of the theory analysis is practical.

Abstract: Flexible fiber Bragg grating (FBG) sensing beams are used to measure dynamic shear response of liquefied soil to ground motions in a shaking table test. Measurement systems typically consisting of bulky arrays of sensor bundles can be instead. But the different frequency response characteristics between the soil and beam generate testing errors. In this work, the sensing beam method is introduced, and the frequency response of the sensing beams will be obtained in an experiment on a shake table.

Abstract: Baishe villagers have lived in loess cave dwelling with pitted courtyard for hundreds of years in Sanyuan County of China .Rainfall infiltration badly destroyed the habitation in recent years so that the study is very important on security and stability of the loess cave dwelling. By field measurements, the sizes of local cave dwellings were mastered and variation was grasped of average annual and monthly rainfall. The physical and mechanical parameters were acquired with loess samples in different water content by the conventional and triaxial soil test. At the same time, based on the literature data, the relationship was established between rainfall and water content. Safety factor was defined for loess cave dwellings in different depths utilizing the expressions of the surrounding rock loop stress and the Mohr-Coulomb theory. The variation of stability of loess cave dwelling could be ultimately analyzed under different rainfall.

Abstract: The shape-stabilized phase-change paraffin at lower temperature is an ideal material used in the phase-change wall. It can enhance the thermal storage capacity of the wall and save energy. The thermal properties of shape-stabilized phase-change paraffin were studied experimentally in this paper. The phase change temperature, latent heat and the stability of shape-stabilized phase-change paraffin with different component were analyzed. The critical mass fraction of paraffin required in the materials was discussed. The results may provide the basis for the application in the practical engineering in the future.

Abstract: By using dynamic and static triaxial experiments to test the saturated composite soil-rock medium of different soil-rock ratio. Measure related power indicators and analyze the variation rules and tendency, and make comparative research on the dynamic and static strength of composite mediums with different soil-rock ratio. Studies have shown the tendency that the static strength and internal friction angle increases while the cohesive force increases and then decreases with the decrease in soil-rock ratio. Under the same compactness, the dynamic strength of composite soil-rock medium increases with the decrease in soil-rock ratio, and decreases significantly with the improvement of seismic intensity; For one rock ratio, dynamic cohesive force decreases with the gradual increase of intensity, and decreases faster with the decrease in soil-rock ratio. While the dynamic internal friction angle decreases with the increase of intensity. At the same intensity, which means the same vibration frequency, dynamic cohesive force increases with the decrease in the soil-rock ratio and so does dynamic internal friction angle.

Abstract: In the analysis of slope stability, a reduction method of non-linear shear strength was applied. A power function was used to approximate the shear failure envelope which is determined by the non-linear criterion or experimental data, and then the coefficients of that function were determined by using the collocation points. The equivalent friction angles and cohesive strengths of rock as well as stress range were determined by fitting an average linear relationship to the approximate curve generated by the power function through the method of least square. Finally, an example was presented to demonstrate the superiority and feasibility of the method introduced in this paper.

Abstract: The mechanical behaviors of a cohesive soil mixing with gravel were investigated in consolidated-drained triaxial tests. Three soils with different percentages of gravel mixed with the cohesive soil, i.e. 50%, 75% and 87.5%, were tested, and the inference of gravel percentage to the stress-strain behavior is investigated. The results indicate that the shear strength of the soil increases with the increase of gravel percentage. Compared to peak strength of GP50, that of GP75 and GP87.5 increases by 14.4%~32.8% and 20.9%~40.5%. The initial and secant Young’s modulus of the soil increases significantly when the gravel percentage is greater than 75%.

Abstract: The high red bed accumulation slope is a particular type in red beds areas that widely spreads in China. The red bed accumulation is of low intensity and poor engineering property, which can easily cause engineering disease. Therefore, the key issue is cutting the stability in slope engineering. Use stress analysis to determine the disturbed zone of the area directly, the project derives disturbed zone slope stability factor and propose the analytical method steps for the theoretical basis of high slope construction stability and the retaining structure design. Use MIDAS/GTS finite element analysis software to simulate two typical red bed accumulation slopes of Guangyuan-Bazhong expressway. The result reveals that the method is feasible and effective through main stress analysis by a reasonable simulate model. For the typical characteristics of high red bed accumulation slope cutting instability, the project provides the reference of design.