Applied Mechanics and Materials Vols. 438-439

Abstract: In order to analyze the influence rule of water pipe cooling on the temperature field and thermal stress of large aqueduct structure, the finite element analysis model for FuYang River Aqueduct structure was established. The temperature field and thermal stress of the aqueduct structure were calculated. The following two cases were considered: structure with or without water pipe cooling, as well as the different beginning pouring months (May, June and July). The hydration-degree-based calculation methods of temperature and stress of concrete were adopted, and the high precision discrete simulation method of water pipe was used. The calculation results show that embedding the cooling pipe in concrete can effectively reduce the temperature difference between inside and outside of the early concrete and thermal stress, and is therefore effective to prevent concrete cracks. High accuracy of simulation and analysis can make people basically figure out the specific mechanism of concrete cracking and main factors even before construction, and determine accurately the structure crack location and the developing tendency.

Abstract: This paper using three-dimensional non-steady, nonlinear temperature field and creep stress field of simulation theory, establishes a FORTRAN program for simulating the temperature and stress during the construction of inverted siphon, analyzes the temperature and stress changes and distribution of siphon walls, and proposes the scientific and reasonable control measures of temperature and crack in a complex external environment. The results show that the wall tends to cracking due to tensile stress at early age within 1 day to 3 days, and insulation measures should be taken into account.

Abstract: The water-collecting well layer of large pump station base plate is constrained by bottom and lateral, and step construction method is used. In view of the characteristics, the simulation is done to study its temperature and stress during construction. Based on a large pump station project and the structural characteristics and construction method of water-collecting well layer, the FEM model is built, and the theories of the 3D-FEM of unstable temperature field and stress field is used to carry out the numerical calculation, which can study change law and distribution of temperature and stress. The results show that the method of step construction can increase concrete cooling during construction, but the heat dissipation potential is difference in different time of day.

Abstract: For sluice concrete structure is more complex due to constrained by the base effect and upper structures, with the purpose of temperature control, we carry out the simulation analysis of temperature and stress during the construction of pier concrete structure. Taking a sluice project as an example, use the method developed by Thermo finite subspace model simulation procedures, the finite element model of pier structure is built with high precision. The results show that the cracking risk is relatively small and prone to surface cracks for baseplate; during construction period, much more attention should be payed to the high temperature difference between day and night, and to the insulation work at cold and windy weather; the key problem is that the middle pier which faces relatively great cracking risk, and necessary temperature control measures should be adopted.

Abstract: In view of the problems of complex geological conditions with high underground water level, large permeability coefficient of soil and the presence of large seepage hazard of deep cut canal and deep foundation pit project of South-to-North Water Transfer Project, China, research on seepage characteristics of digging canals under dewatering well is carried out by finite element analysis, and the FORTRAN procedure is programmed. The three-dimensional finite element model of a digging canal is built, and the seepage field of the different conditions of the canal is simulated, the water head distribution, saturation line and leakages are obtained, and the rules and characteristics of steady seepage field under design impervious system are analyzed. The results indicate that the method can exactly determine the key overflow point and saturation line of canal, and well predict seepage field in canal. The results should be of guiding significance to design and construct retaining engineering in deep cut canal and deep foundation pit.

Abstract: Expansive soils in semi-arid regions are of great concern to design and geotechnical engineers. Damage to residential buildings resulting from expansive soil movements has been widely reported in Australia. This paper describes the current practice in Australia, which includes the site classification, laboratory tests and residential footing design. A case study of a residential house damaged by expansive soils is also presented.

Abstract: The change of micro-structure of the remolded loess is analyzed from the CT numbers and CT images during the uniaxial creep process. It is found that there are quite complex cracks distributed on each layer in the loess during that process. The cracks are not distributed along the radial direction regularly, and the lateral deformation is not obvious.

Abstract: SPT (standard penetration test) is a geo-situ test method widely used in engineering. However, the awareness on modification issues about rod length of SPT-N has considerable differences. Based on the comprehensive analysis of existing research results, some valuable suggestions are put forward contraposed modification issues of rod length, which can be referenced for engineering practices and further research.

Abstract: Principal influencing factors of the strength of rock mass with weak joints were studied in this paper. Dip angles of weak joints in addition with the confining pressure is studied based on strain-softening/hardening plasticity model. The broken mechanism from the perspective of plastic zone was analyzed. The strength of rock mass with weak joints is mainly under control of the joints occurrence, the joints dip and the rock strength, and great influenced by the confining pressure. A higher strength is obtained with a higher confining pressure, the broken mechanisms varies with different joints dips.

Abstract: The test use the practical reduced scale model of flat-bottomed silo to determine the value of static lateral pressure of silo walls, dynamic pressure of discharge process and dynamic pressure of silo walls which comes from eccentric discharge. Then the work is, respectively, to analyses static pressure value and flat-bottomed silo standard value, dynamic pressure value and static pressure value, as well as dynamic silo walls overpressure contrastively, and to calculate the coefficient size of each survey point of silo walls. Thus this trial verifies that the existence of the phenomenon of the silo dynamic overpressure and dynamic overpressure caused by eccentric discharge, also, it illustrates the problem of silo dynamic pressure we cant ignore during the engineering design.