Soft Clay Stabilisation by Mandrel Driven Geosynthetic Vertical Drains

Geosynthetic (prefabricated) vertical band drains are now considered as one of the most cost effective ground improvement technics in many parts of the world, where construction on soft compressible clays is inevitable. However, smear effects caused by PVD installation (eg. mandrel based), drain clogging, drain kinking and well resistance of long drains retard the excess pore pressure dissipation making these drains often less effective in the field, contrary to expectations. Consequently, the rate of settlement of the stabilised soft clay becomes significantly less than what is expected from ideal drains. This paper addresses comprehensively, the numerical modelling aspects of PVD, and the interpretation of field data taken from several case studies, which elucidate the drain performance under various boundary conditions. Theoretical and finite element modelling details are described based on various research studies, mainly through the authors’ own experience. In particular, the experimental data obtained from large-scale consolidation tests are highlighted and interpreted

Modeling of geosynthetic vertical drains in soft clays

Prefabricated vertical band drains are rapidly increasing in popularity as one of the most cost-effective soft clay improvement techniques worldwide. Nevertheless, problems caused during installation (such as the smear effect), drain clogging and well resistance of long drains contribute to retarded pore pressure dissipation, making these drains less effective in the field. This leads to reduced settlement compared with that which would be expected from ideal drains. This paper is an attempt to discuss, comprehensively, the modelling aspects of prefabricated vertical drains and to interpret the actual field data measured in a number of case studies that demonstrate their advantages and drawbacks. Both analytical and numerical modelling details are elucidated, based on the authors\u27 experience and other research studies. Where warranted, laboratory data from large-scale experimental facilities are highlighted

Modelling of Prefabricated Vertical Drains in Soft Clay and Evaluation of their Effectiveness in Practice

Prefabricated vertical band drains are rapidly increasing in popularity as one of the most cost-effective soft clay improvement techniques worldwide. Nevertheless, problems caused during installation (such as the smear effect), drain clogging and well resistance of long drains contribute to retarded pore pressure dissipation, making these drains less effective in the field. This leads to reduced settlement compared with that which would be expected from ideal drains. This paper is an attempt to discuss, comprehensively, the modelling aspects of prefabricated vertical drains and to interpret the actual field data measured in a number of case studies that demonstrate their advantages and drawbacks. Both analytical and numerical modelling details are elucidated, based on the authors\u27 experience and other research studies. Where warranted, laboratory data from large-scale experimental facilities are highlighted