This paper focuses on the underpinning-induced ground movement due to jet-grouting. Jet-grouting technique can cause distortions as a result of an inaccurate processing sequence and/or errors made at different stages ...This paper focuses on the underpinning-induced ground movement due to jet-grouting. Jet-grouting technique can cause distortions as a result of an inaccurate processing sequence and/or errors made at different stages of work execution. The aim of this paper is to determine the minimum value of such movement on the basis of the findings obtained at two similar construction sites located in the Historical Center of Moscow, considering that the maximum value is usually unpredictable. Numerical simulation of the process of soil eroding agrees well with the observational data at the current stage. It was found that the minimum value of deformations （only settlement was considered in this study） due to jetgrouting is no less than 2-3 mm. By contrast, the negative scenario of deformation due to foundation underpinning is clearly demonstrated. Also, this paper provides some general solutions for excavation supporting system as well as for underpinning design.展开更多
This study presents the results of field and numerical investigations of lateral stiffness, capacity, and failure mechanisms for plain piles and reinforced concrete piles in soft clay. A plastic-damage model is used t...This study presents the results of field and numerical investigations of lateral stiffness, capacity, and failure mechanisms for plain piles and reinforced concrete piles in soft clay. A plastic-damage model is used to simulate concrete piles and jet-grouting in the numerical analyses. The field study and numerical investigations show that by applying jet-grouting sur- rounding the upper 7.5D （D = pile diameter） of a pile, lateral stiffness and beating capacity of the pile are increased by about 110% and 100%, respectively. This is partially because the jet-grouting increases the apparent diameter of the pile, so as to en- large the extent of failure wedge and hence passive resistance in front of the reinforced pile. Moreover, the jet-grouting pro- vides a circumferential confinement to the concrete pile, which suppresses development of tensile stress in the pile. Corre- spondingly, tension-induced plastic damage in the concrete pile is reduced, causing less degradation of stiffness and strength of the pile than that of a plain pile. Effectiveness of the circumferential confinement provided by the jet-grouting, however, diminishes once the grouting cracks because of the significant vertical and circumferential tensile stress near its mid-depth. The lateral capacity of the jet-grouting reinforced pile is, therefore, governed by mobilized passive resistance of soil and plastic damage of jet-grouting.展开更多
文摘This paper focuses on the underpinning-induced ground movement due to jet-grouting. Jet-grouting technique can cause distortions as a result of an inaccurate processing sequence and/or errors made at different stages of work execution. The aim of this paper is to determine the minimum value of such movement on the basis of the findings obtained at two similar construction sites located in the Historical Center of Moscow, considering that the maximum value is usually unpredictable. Numerical simulation of the process of soil eroding agrees well with the observational data at the current stage. It was found that the minimum value of deformations （only settlement was considered in this study） due to jetgrouting is no less than 2-3 mm. By contrast, the negative scenario of deformation due to foundation underpinning is clearly demonstrated. Also, this paper provides some general solutions for excavation supporting system as well as for underpinning design.
基金supported by the National Science Foundation for Distinguished Young Scholars of China(Grant No.51325901)the International Science and Technology Cooperation Program of China(Grant No.2015DFE72830)State Key Program of National Natural Science of China(Grant No.51338009)
文摘This study presents the results of field and numerical investigations of lateral stiffness, capacity, and failure mechanisms for plain piles and reinforced concrete piles in soft clay. A plastic-damage model is used to simulate concrete piles and jet-grouting in the numerical analyses. The field study and numerical investigations show that by applying jet-grouting sur- rounding the upper 7.5D （D = pile diameter） of a pile, lateral stiffness and beating capacity of the pile are increased by about 110% and 100%, respectively. This is partially because the jet-grouting increases the apparent diameter of the pile, so as to en- large the extent of failure wedge and hence passive resistance in front of the reinforced pile. Moreover, the jet-grouting pro- vides a circumferential confinement to the concrete pile, which suppresses development of tensile stress in the pile. Corre- spondingly, tension-induced plastic damage in the concrete pile is reduced, causing less degradation of stiffness and strength of the pile than that of a plain pile. Effectiveness of the circumferential confinement provided by the jet-grouting, however, diminishes once the grouting cracks because of the significant vertical and circumferential tensile stress near its mid-depth. The lateral capacity of the jet-grouting reinforced pile is, therefore, governed by mobilized passive resistance of soil and plastic damage of jet-grouting.
