Soil improvement by using deep soil mixing method in approaching nuoc len bridge, ho chi minh city, Viet Nam
THUYET, Tran Van, Dr. Doni Prakasa Eka Putra, ST., MT
2010 | Tesis | S2 Teknik Geologitidak ada Intisari
The study area of Nuoc Len Bridge, located in the western south of Ho Chi Minh City, Viet Nam. The geological condition of this area is mainly soft soil with low bearing capacity. The research is aimed to improve soil foundation at approaching bridge by using Deep Soil Mixing Method (DSMM) which includes deep soil mixing columns system (DSMC). This research analyzes the geological condition of research area and technical specifications of Nuoc Len Bridge to understand the engineering properties of soil foundation (bearing capacity, compressibility, permeability), especially to design DSMC to improve the soft soil (increase the bearing capacity, decrease the settlement, reduce the soil improvement period). The analyses were performed by manual and modeling analysis. The manual analysis identifies the settlement of soil foundation, the optimal spacing of columns and the effects of DSMC for soil improvement. The modeling analyzes behaviors of soil foundation to simulate displacement and stability of approaching bridge. The analysis results show that the soil foundation of research area is soft clay layer with about 25 meters in thickness, low bearing capacity, high compressibility; In case non-improvement, the consolidation process of soft clay happens slowly (more than 50 years) and the settlement of clay layer is so high (about 2.80 meters). In case applying DSMC, the settlement is reduced significantly (the maximum settlement is 0.099 meters) and the time for soil improvement is short (about 2.5 months). Specifications of Deep Soil Mixing Columns are designed to achieve these effects are such as: the strength (500 kN/m2), the diameter (0.7 meters), the length (26 meters) and the columns are installed from ground surface to sand layer (under soft clay layer), the spacing of columns increase gradually according to the decrease in height of approach, it is from 1.2 to 1.9 meters; From simulation of Plaxis, the maximum vertical displacement of approach (it is also settlement of soft clay) is 2.86 meters in case non-improvement and is 9.8 centimeters in case that soft clay is improved by DSMC, the safety factor of approach after DSMC is applied is fairly high (about 1.459). From the manual and simulation results, the applying DSMC for soil improvement has some effects: reduction of settlement, reduction of construction period, the Nuoc Len Bridge’s approach can be stabilized for the long time. The most important, the error between manual and simulation results is small, so the results of calculation can be significant
Kata Kunci : Soil improvement,Approaching nuoc len bridge,Ho Chi Minh,Viet Nam
