Advanced Materials Research Vols. 368-373

Abstract: According to Moore-Coulomb strength theory, combined with the shear strength reduction method, assumed that the exerted value of the soil’s internal friction Angle and displacement were in nonlinear, and the exerted value of the soil’s cohesion and displacement were in linear, and then put forward a unified, continuous with displacement earth pressure calculation model, and this model could be used to calculate the active and passive earth pressure for cohesive soils and cohesionless soils in any nonlimited state and any movement mode. Through the analysis of the calculation model showed that: (1) The above assumptions were all reasonable from the two perspectives of the theoretical and the measuring; (2) The variation process of earth pressure acted on the retaining wall with displacement, could regard as the process of the soil’s shear strength parameters exerting gradually; (3) Given the physical meanings to the calculated parameters; (4) Analyzed the characteristics of the calculation model, and pointed out that there were calculation errors when the displacement of retaining wall was in (0, x0H) for the Rankine earth pressure theory.

Abstract: The elastic foundation beam method is the main method of stress analysis of the supporting structure of the foundation pit, it can easily calculate the internal forces and displacement of the structure, however, the computing method of elastic foundation beam deflection equation is more complicated. So according to the computation principle and method of elastic foundation beam, a computing program has been programmed by MATLAB mathematical software. The program has been applied to compute the internal force and deformation of deep foundation pit of Suzhou subway station. The variation law of displacement and bending moment of supporting structure during excavation has been obtained. The results of the measured and calculated agree well, and the computing results have efficiently guided and optimized supporting design.

Abstract: The reasons of the soil mechanical behavior shown are the property of their internal microstructure changes in the external reflection, so with soil micro-mesostructures to analyze soil macroscopical mechanical properties is a good research method. The current concepts of common soil test methods are mainly CT technology, SEM technology, mercury intrusion technology and high-resolution camera technology. On the basis of elaborate all kinds of the test of fine view about the principles of test methods ,the principle of the steps and its characteristics ,and by comparison and analysis of the advantages and disadvantages of the test methods are given and the scope of various test methods to promote the study of the soil micro-mesostructures.

Abstract: This paper selected representative soft site along the subway lines and created two-dimensional overall finite element analysis model about nonlinear dynamic interaction among soil, underground subway station, and ground structure based on Nanjing underground subway station. It explored the seismic response influence of neighboring high-rise structure on the two-layer and three-span island-type underground subway stations. The results showed that the structure near the subway station had a significant constraint effect on the deformation of subway station which is oriented to the structure, and the influence of deformation of subway station which is backward to the structure is related to vibration characteristics of the soil-underground structure interaction system. The influence of neighboring ground structure on the strain stress response of subway station is useful in most part of important nodes. However, this influence is disadvantageous in the outer part of connections of side walls and plates and middle plate-interior column connections.

Abstract: A fitting function of lateral displacement of cemented soil retaining wall was proposed according to several measured data of excavations. On this basis, the retaining wall was treated as a homogeneous elastic vertical beam, whose toe and heel were restricted by a spring constraint but still could be moved and rotated. An analytical formula of the lateral displacement of the retaining wall was deduced with the principle of minimum potential energy with consideration of all the external forces. Compared with some other measured data, the average relative error of the formula was less than 10%, which preliminary indicated the formula’s practical value.

Abstract: Laterite contacted with alkaline materials, was significantly corroded under same conditions, it to be found in the processes of dam safety identification. Alkaline materials properties and acid-alkali reaction were analysed, and supersaturation emulsion calcium hydroxide was used to immerse laterite at constant temperature. Then changes of ion concentration were detected in exudates, change trends of grain size gradations were analysed, and evolutions of pore were observed in laterite. Mechanism of laterite chronically eroded by alkaline materials is opened out, which is neglected by engineers and has become one of the main reasons why reinforcement benefit is always too low.

Abstract: The subgrade at the end of a bridge near some important buildings,such as bridge abutment and 500KV transmission line. To meet of the demand of construction period, Different technique of blasting benches were adopted in different district. And meanwhile，safety control was also strengthened in the blasting operation. The blasting successfully made the bridge abutment and the fly-rock under control.

Abstract: Through numerical simulation，the article analyzes the difference of ground surface acceleration response under the condition of free site and underground structure. The result shows: compared with free site, the underground structure has a greater influence on the peak value of ground surface acceleration and response spectrum. The paper also presents the influencing regularities.

Abstract: All the time, security control method of loading is an important research part in the surcharge preloading, which is directly related to safety of the construction process. Starting from the stress path, discussing the variation of excess pore water pressure and relationship between stress path and security, and bringing forward the control method with a safety factor F_s based on the stress path. By measuring the change of excess pore water pressure, the control method with a safety factor F_s can reflect quantitatively the security status of soil and achieve the purpose of the process control, finally the security control method including the safety factor of loading and speed control is put forward to monitor construction safety. The safety factor of loading F_s is verified and back analyzed with the finite-element software, getting the correction factor from 0.90 to 1.20.

Abstract: A frequently used technique for improving the performance of geotechnical structures consists in incorporating into the backfill soil, during the construction process, regularly spaced thin reinforcing inclusions, called geotextile, geomembranes or geogrids. The stability of embankment, stabilized by reinforcing membranes, is investigated by means of a multiphase model developed in the framework of the yield design approach. By means of the kinematic approach, leading to upper bound estimates for the stability factor of the structure.