On the basis of Terzaghi's one-dimensional consolidation theory, the variation of effective stress ratio in layered saturated soils with impeded boundaries under time-dependent loading was studied. By the method o...On the basis of Terzaghi's one-dimensional consolidation theory, the variation of effective stress ratio in layered saturated soils with impeded boundaries under time-dependent loading was studied. By the method of Laplace transform, the solution was presented. Influences of different kinds of cyclic loadings and impeded boundaries conditions were discussed. Through numerical inversion of Laplace transform, useful illustrations were given considering several common time-dependent loadings. Pervious or impervious boundary condition is just the special case of the problem considered here. Compared with average index method,the results from the method illustrated are more accurate.展开更多
Microbe-induced calcite precipitation is a sustainable improvement technique for sandy soil, which can alter the properties of sand via microbial activity. In this study, we investigated the loose-sand-consolidation e...Microbe-induced calcite precipitation is a sustainable improvement technique for sandy soil, which can alter the properties of sand via microbial activity. In this study, we investigated the loose-sand-consolidation eff ect by controlling the injection velocity, bacterial and cementingsolution concentrations, and hold times. The results demonstrate that, as the cyclic batch increases, the utilization rate of the bacterial fl uid increases and both the optical density(OD_(600)) of the bacteria and urease activity decrease. Moreover, it was determined that a 3-h hold time for a 0.5 mol/L cementing solution with a cementing fl uid velocity of 2 mL/min has the greatest bonding eff ect. The fi nal strength of the loose sand with an increase in calcium carbonate content was further discussed.展开更多
The large-scale bucket foundation with 30 m in diameter and 6 m in height was used as the foundation of wind turbine. The wide-shallow foundation is different from the traditional bucket foundation with high ratio of ...The large-scale bucket foundation with 30 m in diameter and 6 m in height was used as the foundation of wind turbine. The wide-shallow foundation is different from the traditional bucket foundation with high ratio of height to diameter. The cover-load-bearing mode of the new type foundation can resist more external loadings. To achieve the bearing mode, the muddy soil inside the bucket should be reinforced, which will improve the soil strength and make the soil and foundation into a whole part to resist the external loadings. The vacuum and electro-osmotic soil reinforc- ing methods were used in the experiments. The results showed that the bearing behavior of the muddy soil were effec- tively improved by the negative pressure and electro-osmotic effect, and the improved muddy soil with better strength could work together with the bucket foundation, meaning that the top-cover bearing mode of the new bucket founda- tion was achieved. During the soil reinforcing process, the foundation moved downward, i.e., the settlement of founda- tion was almost finished during the pre-loading process caused by the vacuum and electro-osmotic method.展开更多
文摘On the basis of Terzaghi's one-dimensional consolidation theory, the variation of effective stress ratio in layered saturated soils with impeded boundaries under time-dependent loading was studied. By the method of Laplace transform, the solution was presented. Influences of different kinds of cyclic loadings and impeded boundaries conditions were discussed. Through numerical inversion of Laplace transform, useful illustrations were given considering several common time-dependent loadings. Pervious or impervious boundary condition is just the special case of the problem considered here. Compared with average index method,the results from the method illustrated are more accurate.
基金supported by the National Key Research&Development Program of China(no.2016YFC0401904)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(no.51621092)+1 种基金the National Natural Science Foundation of China(nos.51309177 and 51409187)the Program of Introducing Talents of Discipline to Universities(No.B14012)
文摘Microbe-induced calcite precipitation is a sustainable improvement technique for sandy soil, which can alter the properties of sand via microbial activity. In this study, we investigated the loose-sand-consolidation eff ect by controlling the injection velocity, bacterial and cementingsolution concentrations, and hold times. The results demonstrate that, as the cyclic batch increases, the utilization rate of the bacterial fl uid increases and both the optical density(OD_(600)) of the bacteria and urease activity decrease. Moreover, it was determined that a 3-h hold time for a 0.5 mol/L cementing solution with a cementing fl uid velocity of 2 mL/min has the greatest bonding eff ect. The fi nal strength of the loose sand with an increase in calcium carbonate content was further discussed.
基金National Hi-tech Research and Development Program of China("863"Program,No.2012AA051705)National Natural Science Foundation of China(No. 51109160)
文摘The large-scale bucket foundation with 30 m in diameter and 6 m in height was used as the foundation of wind turbine. The wide-shallow foundation is different from the traditional bucket foundation with high ratio of height to diameter. The cover-load-bearing mode of the new type foundation can resist more external loadings. To achieve the bearing mode, the muddy soil inside the bucket should be reinforced, which will improve the soil strength and make the soil and foundation into a whole part to resist the external loadings. The vacuum and electro-osmotic soil reinforc- ing methods were used in the experiments. The results showed that the bearing behavior of the muddy soil were effec- tively improved by the negative pressure and electro-osmotic effect, and the improved muddy soil with better strength could work together with the bucket foundation, meaning that the top-cover bearing mode of the new bucket founda- tion was achieved. During the soil reinforcing process, the foundation moved downward, i.e., the settlement of founda- tion was almost finished during the pre-loading process caused by the vacuum and electro-osmotic method.
