Papers by Keyword: Soft Soil

Abstract: For a better design of Jet Grouting (JG) and Cutter Soil Mixing (CSM) technologies, a set of laboratory formulations are usually prepared aiming to give a first idea of the mechanical behavior of the final mixture. However, these formulations can represent an important cost to the project. Therefore, aiming to reduce such cost, in the present work the analytical expressions proposed by Eurocode 2 for strength and stiffness prediction of concrete were adapted to soil-cement laboratory formulations for JG and CSM projects. It is shown that these expressions can be successful applied in mechanical properties prediction over time of soft soil stabilized with cement for a wide range of cement content, water cement ratios and soil types.

Abstract: The differential and large settlement may have a great effect on the construction and maintenance of highway. Based on the study of concrete pile composite foundation, the effect of concrete pile composite foundation on reinforcement and influence factors of settlement are analyzed in the paper. The effects of pile modulus and embankment modulus on settlement with numerical simulation method are analyzed in the paper. The result of numerical simulation method is that the settlement of embankment may be reduced with the method of concrete pile composite foundation and pile modulus may have a great effect and embankment modulus may have some effect on the settlement of embankment.

Abstract: In order to avoid the limitations in traditional methods of basal heave stability analysis for deep foundation pit, numerical analysis was adopted by establishing a two-dimensional elasto-plastic finite element model. Resistant heave stability safety factor was calculated using the fitting formula acquired from the simulated results, and then the upheaval value and plastic range under critical conditions were studied. The results show that the soil stress will be redistributed with the increasing of excavation depth until upheaval damage taken place. The upheaval value will be larger, the plastic range will be greater, and the basal heave stability will be worse with the decreasing of plastic parameters. Meanwhile, the basal upheaval peak position will transform gradually from excavation center to diaphragm neighborhood with the decreasing of plastic parameters. There is a critical value associated with supporting parameters for soil plastic parameters and the possibility of upheaval destruction increases significantly if the plastic parameters are less than the critical value.

Abstract: The degree of improvement of a soft soil by stone column is due to the inclusion of a stiffer column material and the densification of the surrounding soft soil during the installation of the vibrocompacted stone column itself and the subsequent consolidation process occurring in the soft soil before the final loading of improved soil. Research study on different materials for stone column has not attracted much attention. A systematic verification of the effectiveness of different materials for stone column need to be carried out. It is an important output to be presented as a general guidelines for the selection of proper stone column material which can be used effectively and economically.

Abstract: The article through to free vibration column experiment research to soft soil of Binhu new district of Hefei, The data and curves are given for four types of soil dynamic shear modulus and damping ratio with shear strain and draw rules of different size of confining pressure on the dynamic shear modulus and damping ratio of soil. For hefei binhu new area soft soil of the physical and mechanical characteristics, select the optimal soft foundation treatment scheme, practical design calculation model is set up, and perfect the construction technology measures, the article has some reference value.

Abstract: With the improved direct shear creep apparatus, the rheological material composition and its spatial distribution effects on aging deformation characteristics of soft soil. Four sets are finished including organic clay, quartz and feldspar with different weight percentages and rheological properties of different spatial distribution of sample testing in the same experimental conditions. Test results show that flow in any matter content ratio has significant effects on the rheological properties, the influence of the spatial distribution of waning gradually, and with the uniformity of the distribution and uniformity of the critical value. When a disguised form of size is less than the critical size of soil, soil aging deformation characteristics associated with the flow in a disguised form content ratio, and had nothing to do with the space distribution.

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: Based on the triaxial test results of soft soils, an error back propagation network predicting model for deformation property of soft soil is built. Improved BP neural network model is trained by additional momentum term, adaptive learning rate and Bayesian regularization performance function. Research shows that improved BP neural network model applied to predict soft soil foundation settlement, has fast computation, high accuracy, strong generalization ability, and good capability of matching the real data and the measured one. According to test data, the creep models can avoid any artificial assumption of complex constitutive equation, and can reflect nonlinear creep properties of soft soil objectively, thus has better fault-tolerance and more convenient than the traditional method.

Abstract: There is the soft soil distribution mostly in the regions along the river or the sea in our country, so the soft foundation treatment shold be well done in building highways. With respect to the soft foundation treatment methods, the scholars, engineers and technicians home and abroad have put forward a dozen or more methods, such as replacement method, reinforcement method, top pressing method, sandstone pile method and deep mixing method etc.. This article discusses the reinforcement mechanism, construction technology and some proceedings requiring attention in the construction and detection of the cement agitation pile.

Abstract: The rapid development of China’s economics makes it urgent to widen the existing highways especially those located in the south-eastern coastal areas over thick soft soils. Adding a new embankment adjacent to the existing highway embankment is a cost effective choice compared with the traditional methods to build another new one and can reduce the heavy traffic pressure. However, it may also cause some engineering problems including the excessive settlements settlements, road cracks, excessive tensile stresses on the pavement even local or global instability of embankments. So some proper measures should be taken to solve the problems caused by widening is of great importance in engineering practice. A numerical analysis was performed to investigate the effect of different kinds of soft soil treatments including rigid piles, stone columns and prefabricated vertical drains (PVDs) usually used in highway widening projects located in the thick soft soils. It was found that the rigid piles can effectively reduce the additional settlements of the existing embankment induced by widening as well as the settlements of the widened embankment. While the stone columns and PVDs play little role in controlling the additional settlements caused by widening.