Applied Mechanics and Materials Vols. 353-356

Abstract: Pile tip absolute settlement curves and relative settlement curves of several working cases were analyzed. It is found that load-settlement curve characteristic related to the selection standard. The tip resistance initial stiffness of each case was analyzed. Results show that the small diameter pile has higher initial stiffness than large diameter pile, embedded depth has little influence on initial stiffness ratio, but increment of initial stiffness is linear with embedded depth growth.

Abstract: Landfills come with a cover barrier which includes a compacted clay liner essential to safety on site. Unfortunately differential settlement may cause stress in the clay layer leading to the development of cracks. This is why tensile stress damage and shearing are observed on the cap cover. Due to difficulties of strains determination in clayey soil during direct tensile tests a 3-dimensional digital image correlation is used. Two digital cameras are used at a constant distance from the sample tested. Pictures taken at preset intervals are post-processed to extract specimen strain and strain localization. The suitability of this method is discussed in regards of experimental results. This technique is particularly well adapted to the clayey soils when conventional measurements are impossible.

Abstract: Nanjing-Hangzhou Railway Passenger Dedicated Line is a high-speed railway of the speed 350 km/h in coastal soft area without railway track ballast. The settlement of soft foundation is quite great and the strict control standards of the settlement after construction of the high-speed railway that the settlement observation in construction phase is very strict. Through the settlement observation data analysis of Nanjing-Hangzhou Railway Passenger Dedicated Line on-site, the author found that the preloading can rapidly accelerate the settlement of the soft soil subsidence, the settlement is quite great during the embankment construction and the later three months, there is a preloading critical height, the foundation generally does not rebound when load was removed, the settlement trends are consistent with the three-point analysis. These conclusions are certain referential significance for the settlement control of the coastal soft soil area of high-speed passenger dedicated .

Abstract: It is of great importance to guarantee the safety of slope and buildings when driving a horizontal chamber in the slope.In order toresearch slope stability while driving the horizontal chamber on this slope, the software FLAC3D was used to study the horizontal displacement of slope soil in different driving depth. The transverse settlements rules of the slope soil and the building foundation are analyzed numerically. And the numerical simulation results were compared with field monitoring. The results show that both the maximum transverse settlements position of the slope top and the building foundation were at the center line of the chamber. The horizontal displacement values were larger at the top andend but smaller in the middle. And it is beneficial for the slope stability and the buildings safety to enhance the supporting parameters of the entrance zone of the chamber. The results from the numerical simulation are consistent with the field monitoring, which can supply a reference for the similar engineering.

Abstract: Artificial ground freezing method is now widely used in many kinds of municipal projects. The existing formulas to calculate the temperature field distribution of single-row piped freezing are all based on the conditions that the temperature of all freezing pipes are equivalent. In this paper, analytical solution to steady-state temperature field of single-row piped freezing with different adjacent pipe surface temperatures was derived based on thermal potential superposition method. And discussions are made to analyze the influence of temperature difference between adjacent pipes and freezing time on temperature distribution of frozen soil.

Abstract: The dynamic compacted replacement pier technique is a new ground-treatment technology, which developed from the dynamic consolidation method. It can be used for the improvement in high-saturated silts and soft plastic to flow plastic clays, which cannot be treated using dynamic compaction method. T his new approach has many advantages, such as its simple equipment, significant reinforcing effects, construction time-saving, low-cost, no requirement of dewatering, and etc. In this paper, combined with engineering examples, according to analysis and evaluation of the monitoring results, it is feasible to adopt dynamic compaction replacement pier in uneven thickness hard plastic silt-clay foundation. Concrete-gravel dynamic compaction replacement pie can enhance the bearing capacity of pier and compound foundation. It provides a practical basis to expand the application scope of dynamic compaction replacement foundation treatment and enrich this technology.

Abstract: This paper uses finite element numerical simulation method to analyze the rock mass stress deformation characteristic and it illustrates that site stress state is mainly controlled by the gravitational field, while the rock basic deformation is solidification. On the foundation of blocks limit equilibrium calculation results, it shows that the global stability of the site is in good condition in a variety of extreme circumstance conditions. The blocks stability is slightly lower than sites whole stability, which is in the front edge of the site, controlled by secondary slip surface II.

Abstract: A new method for reliability and sensitivity analysis of slope stability is proposed in this paper, which is based on strength reduction FEM. In this proposed method, the safety factor of slope can be calculated without assuming the shape and position of failure surface beforehand, and the randomness of physical and mechanical parameters of slope are considered in the calculation process. Meanwhile, the slopes failure probability is researched when the coefficients of variability change, and some useful conclusions are achieved.

Abstract: The primary methods are antetype observation and model tests which to check the actual engineering status in geotechnical engineering field. The antetype observation is the best direct and convictive method, but approach miscellaneous and spend hugely. The general model tests can not fulfil the same stress between model and antetype. Geotechnical centrifuge model test can not only minish the measure of model and fulfil the comparability condition, but also can found all kinds of non-symmetrical models and simulation all kinds of complicated engineering. So the geotechnical centrifuge model test is applied widely in the geotechnical engineering. This paper used the RFPA-Centrifuge and recured to the principle of geotechnical centrifuge model test, evaluated the safety of model only by increase the physical strength. Though the numerical calculating in nonhomogeneous models with different scales showed that stress, displacement and failure mode were accord with conform ratio of centrifuge model tests. Showed the advantage that the results of RFPA can be validated each other with results of physical tests. For some specifical complicated items in geotechnical engineering, make a good test model is not only very hard and have to spend much time, but also need expensive test equipment and much money for test materials. It is very good if we can use a method to conquer these shortages. So it is advisable that using the mechod which geotechnical centrifuge tests combine RFPA-Centrifuge numerical simulation analysis method.

Abstract: Based on Abaqus/explicit dynamics finite element program, an ax symmetrical numerical model, the infinite fringe condition and friction contact condition were built, and then the surface contact stress condition of the dynamic consolidation was studied. The time-load properties of dynamic consolidation, the spread law of contact pressure for rammer bottom and the friction influence to contact stress between the hammer and foundation were gained. The results indicate that the dynamic consolidation load can be simplified to triangular load with the weight of the hammer itself; the contact stress distribution between the hammer and the foundation is not uniform; and frictionless contact hypothesis can led errors to the simulated result.