Papers by Keyword: Soft Ground

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Authors: Yeong Mog Park, Ik Joo Um, Norihiko Miura, Seung Cheol Baek
Abstract: The purpose of this study is to investigate the undrain shear strength increment during consolidation process of soft clayey soils. Thirty kinds of laboratory triaxial tests have been performed using undisturbed and remolded Ariake clay samples with different degree of consolidation and 5 kinds of confining pressure. Test results show that well known linear equation proposed by Yamanouchi et al.(1982) is overestimated the strength of undisturbed soft clay ground in the process of consolidation. A new simple and reasonable exponential equation proposed in this paper.
Authors: Bin Bin Xu
Abstract: The soft ground including the mud, muddy clay, silty clay etc. is widely distributed in the coastal areas of China. Due to the poor permeability and low bearing capacity, ground improvement is usually necessary before construction. Owe to the low cost and high efficiency, the drainage consolidation methods including surcharge preloading and vacuum preloading methods are the most popular method for the improvement of the soft ground. The consolidation theories are introduced according to the time sequence and the emphasis is put on the radial consolidation theories considering the smear effect and the well resistance.
Authors: A Lan Jiang, Mei Xia Wang
Abstract: With the rapid development of high-speed railway in soft foundation, foundation treatment technology has become mature, the most outstanding is CFG pile composite foundation technique. CFG pile composite foundation is made of cement fly ash gravel pile(CFG pile), pile of soil and sandstone , between sand and gravel several problems such as the medium material composition together constitute layer. It has high bearing of capacity, convenient, low costing, strong adaptability and quality control easier.So it is widely applied and promoted. Under static and dynamic loads, the relations of the high-speed railway CFG pile composite foundation is very complex. In order to further understand the intensity of pile-net structure subgrade stability and deformation, pile , requirements of the high-speed railway roadbed ,it needs to do pile-net structure parameter sensitivity analysis. According to high-speed railway CFG pile composite foundation , the numerical analysis can well solve the coupling effect of piles and soil. So, this paper adopts FLAC3D finite difference software is simulated and analyzed.
Authors: Xin Quan Wang, Yun Liang Cui, Jian Feng Liang, Shi Min Zhang, Yi Qun Tan, Yu Feng Guan, Guang Hai Gu
Abstract: By adopting the conventional pile foundation to treat the area of thick overburden on soft soil, the reinforcing effect can’t meet the use requirement: by adopting the bulk material pile, the lower pile body strength can’t be ensured, and by adopting the cemented soil mixing pile for reinforcing, the pile is difficult to form and the reinforcing depth can’t meet the requirement. This paper aims to overcome the defects of the conventional construction method by adopting different materials to treat, namely, the concrete rigid pile is adopted for reinforcing the soft soil layer with poor soil body quality and the cement mortar flexible pile is adopted for reinforcing the overburden with excellent soil body quality, therefore not only the reinforcing effect is ensured, but also the construction cost is saved.
Authors: Chuang Yu, Xiao Qing Cai, He Jun Wu
Abstract: With the demand of economic development and traffic modernization process, the construction of highway engineering in China has come into a fast period. This paper investigates the settlement of the highway embankment using the finite element software Plaxis. The embankment settlements at different locations with time are presented. Compared with the measured settlement-time data, it is concluded that the computed results kept good agreements with measured data. The results show that the software Plaxis has certain accuracy in the calculation of the embankment settlement over soft clay ground, which could be intended to provide a reference for engineering practice. The presented numerical simulation model can be applied to predict the settlement during the filling process of embankment.
Authors: Rong Yao, Meng Yun Mao, Yun Que
Abstract: There ware numeral analysis by ABAQUS finite element software to discover the pile’s status with unloading abutment in soft ground, three model were built, first model was unloading abutment and pile supported reinforced embankment, second model was only unloading abutment, third model was only pile supported reinforced embankment, the piles horizontal displacement, axial force and bending moment were discussed; the results show that the piles horizontal displacement with pile supported reinforced are smaller than the others models, pile axial force in three model are little difference.
Authors: Nur Fadilah, Ong Chong Yong
Abstract: Precast concrete sheetpile designed to restore and protect a road embankment, undergoing continuous settlement in soft ground condition in Jerlun and Kuala Sanglang in the state of Kedah, Malaysia is presented. The road built on soft ground has been in service for several years with some anticipated settlements. Major defects in the form of uneven settlements were spotted after few years of service. A survey was conducted and 5 spots along a 30m to 40m long stretch experiencing about 100mm settlements relative to the centerline of the road. Several attempts have been made to backfill and re-surface the affected areas but the road conditions did not last, posing danger to motorists. Investigations have revealed slip circles did occur at the affected areas with signs of lateral movements of earths towards the river. Precast concrete sheetpiles were designed to stabilize the road embankment to prevent further lateral movements of earth due to vehicular loads on the road. Analysis and design of the sheetpile system are presented. Construction aspects related to handling, installing and finishing works at site are highlighted.
Authors: Xi Zuo, Guo Xing Chen, Zhi Hua Wang, Xiu Li Du
Abstract: Based on the test data of shaking table tests of subway station structure in soft ground under both near-field and far-field earthquakes, the spatial effects of peak ground acceleration (PGA) of soft ground as well as peak strain response of the subway station structure are analyzed. The results show that the peak acceleration of measuring points on both major and minor planes increases with the growing peak acceleration of earthquake. The law of PGA and frequency spectral character of measuring points on different observation planes or at different depth varies with each other, and there presents remarkable spatial effect. The peak strain of central cylinders on the major plane appears larger than that on the minor planes. There are sharp contrasts among the peak strain responses in different spatial positions of the station structure.
Authors: Yu Chun Cao
Abstract: Due to the uncertainties and randomness of earthquake loads, it is more logical that reliability method should be employed in dynamic geotechnical engineering analysis. A methodology of 2-D effective stress FEM analysis based on dynamic reliability of seismic response of soft ground including silt is proposed in this paper, Duncan-Chang and Hardin-Drnevich hyperbolic models are used for static and dynamic constitutive relations of soils, respectively. Furthermore, three stochastic dynamic reliability analysis approaches based on the cumulative damage, cyclic shear stress and pore water pressure ratio are respectively suggested. The proposed methodology was applied to the stochastic dynamic reliability analysis of ground seismic response of two typical soft soil profiles in Shanghai in terms of seismic wave input depths of 50m and 280m. Basically consistent conclusions can be drawn in the three aforementioned perspectives. In addition, the filtering effect of frequency components by deeper soil layers plays perhaps an important role in dynamic reliability analysis in view of the fact that remarkable differences of dynamic reliability analysis results exist between 50m and 280m seismic wave input depths.
Authors: A Lan Jiang, Mei Xia Wang
Abstract: The settlement of railway subgrade has an important connection with the quality, safety and natural life of the railway, the excessive settlement of subgrade will directly cause too many problems in the process of railway using. Especially in high speed railway, these problems will be more outstanding, thus affecting the development and progress of the railway. For the foundation of traffic infrastructure in areas with soft subsoil often embankments supported by piles are necessary due to the settlement requirements. For sufficient load transfer into the piles different construction methods are possible. For the construction of a high speed railway, a cement stabilization of the embankment material and geogrid reinforcement on top of the piles were used. Before the temporary load the settlement is monitored continuously for 10 months. In this paper, the method of construction is described and important field monitoring results are presented.
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