Advanced Materials Research Vols. 243-249

Abstract: Based on the model of effective friction coefficient, the change tendency of effective friction coefficient under different harmonic forces and the method of improving its decrease rate have been studied. The model of vibratory piling machine has been taken as a research object for friction reduction, and the stress of soil particles and the situation of friction resistance on pile surface have been analyzed while sinking the pile. The effect on interface friction of pile-soil system under vibration, caused by the depth of pile sinking, pile structure parameters and vibration acceleration, has also been studied, so that an effective method of decreasing interface friction can be found. Thus, the sinking efficiency would be improved by being analyzed, evaluated and parameter optimized.

Abstract: Large-span hybrid structure of suspendome with stacked arch is applied into steel roof of Chiping Gymnasium. The construction of this new type structure system is difficult according to structure characteristics such as its large-span stacked arch, high installation altitude, lattice shell installation, prestressed cable tension, and tight construction period. Temporary support frame, segment lifting and high altitude splicing construction method is adopted to install the stacked arch, and total support, high-altitude spread operation method is used to install lattice dome. A spatial structural analysis is conducted on the supporting system, and the finite element software is adopted to simulate and analyze the installation process of the steel structure roof system. At the same time, stress and deformation of the roof structure are monitored by precise instruments and equipments. As the result, construction safety and quality are guaranteed.

Abstract: To meet the demand of high performance of mass concrete in a pile cap of well tower, excessive replacement of fly ash was applied to the mass concrete. Based on the theory of hydration heat of cement, several thermal parameters of mix proportion were analyzed and simulated test analyses and setting time test analyses were conducted in the laboratory. The results and data collected in the project locale both show that applying excessive replacement of fly ash reduces hydration heat of mass concrete in the pile cap of well tower, which extends setting time in mass concrete and avoids the cracks caused by temperature stress. The results achieve favorable effect and provide reference for design and construction of mix proportion in the project of mass concrete.

Abstract: Combined with a specific foreign-related project and based on the detailed report of the engineering geological investigation, this paper describes the application of the selected support structures of shotcrete-bolt and bored piles with high pressure rotary jet grouting waterproof curtain from aspects of scheme optimizing, design and construction, underground watertable lowering and result monitoring. Satisfactory achievements have been made in cost saving, shortening duration, facilitating construction and environmental protection etc. It demonstrates that two or multiple support systems can be used simultaneously in one foundation pit as support structure.

Abstract: The reinforcement in both directions of a square tower crane foundation is obtained by ANSYS three-dimensional analysis and VB reinforcement program and VB optimization program to meet the requirements such as foundation bearing capacity, bending, overturning and punching under the general combination of various loads.

Abstract: This paper proposes a research work that characteristically analyzes the component differences between new and aged pavement asphalts. Both the new and aged pavement asphalts are sampled from the same type and separated into four components: saturate, aromatic, resin and asphaltine. Based on the comparative analysis regarding the masses, functional groups and structural features of each component, it is found that the aged asphalt has less saturate and aromatic but more asphaltine, lower mass ratio of resin to asphaltine, and decreased compatibility of asphatine with saturate and aromatic. Also, although there is little change in the infrared spectra of saturate and aromatic, the infrared spectra of asphaltine are different, with those oxides that contain C, N and S being significantly increased in the aged asphalt.

Abstract: Through the analysis of the present situation of water-saving in building water supply and drainage in our country to realize that some problems still exist in the water conservation consciousness, water saving technology, water-saving management etc, stating there is great space in water-saving, to ensure the water-saving society construction and save and protect the water resource, we should further improve water saving consciousness, changing the traditional water-using habits and improve water management way; Constantly innovating water-saving technology, researching and promoting water-saving facilities and equipment. dominated by the government, Comprehensive use of publicity and measure of administrative, law, management, economy, education and scientific means, unifying management, configuring scientifically, only this can solve the conflict of supplying and demanding to a certain extent and the lack of water in peak hour, it can ease the tension in water supply and protect the environment, bringing good environmental, social and economic benefits.

Abstract: In recent years, a lot of research practices have been done on improving the quality of subgrade construction and solving the differential settlement of subgrade. Therefore, key construction technology for highway on soft foundation is very important. This paper analysis common engineering problems on soft foundation and the development status for soft soil treatment technology, then build up the technology trends on it.

Abstract: The purpose of this paper is to develop the Ⅰ-PreConS (Intelligent PREdiction system of CONcrete Strength) that predicts the compressive strength of concrete to improve the accuracy of concrete undamaged inspection. For this purpose, the system is developed with adaptive neuro－fuzzy inference system (ANFIS) that can learn cube test results as training patterns. ANFIS does not need a specific equation form differ from traditional prediction models. Instead of that, it needs enough input-output data. Also, it can continuously re-train the new data, so that it can conveniently adapt to new data. In the study, adaptive neuro－fuzzy inference system (ANFIS) based on Takagi-Sugeno rules is built up to prediction concrete strength. According to the expert experience, the relationship between the rebound value and concrete strength tends to power function. So the common logarithms of rebound value and strength value are used as the inputs and outputs of the ANFIS. System parameter sets are iteratively adjusted according to input and output data samples by a hybrid-learning algorithm. In the system, in order to improve of the ANFIS, condition parameter sets can be determined by the back propagation gradient descent method and conclusion parameter sets can be determined by the least squares method. As a result, the concrete strength can be inferred by the fuzzy inference. The method takes full advantage of the characteristics of the abilities of Fuzzy Neural Networks (FNN) including automatic learning, generation and fuzzy logic inference. The experiment shows that the average relative error of the predicted results is 10.316% and relative standard error is 12.895% over all the 508 samples, which are satisfied with the requirements of practical engineering. The ANFIS-based model is very efficient for prediction the compressive strength of in-service concrete.

Abstract: Concrete might be subjected to impact or blast loading. To analyze the concrete behaviors under such loading cases, it is of interest to study the dynamic damage and failure behavior of concrete under high strain rate. In the present paper, a mesoscale model is developed to numerically analyze the dynamic damage process of concrete samples under high strain rate tension. In the mesoscale model, the concrete is regarded as a three-phase composite consisting of coarse aggregate, mortar matrix, and interfacial transition zone (ITZ) between the aggregate and the mortar matrix. Different coarse aggregate shapes, such as circular, oval, and polygon, are calculated and compared. It is found that the shapes of the coarse aggregates do affect the tensile strength and failure pattern.