Bag Tests are a Good Field Measurement of Geotextile Tube Performance

摘要

The use of geotextile tubes is a cost effective method for dewater-ing dredged materials. Early in the design phase of a dredging project, the engineer must determine the client's requirements and priorities, such as reduced turbidity of the dredge discharge to comply with environmental regulations. Other requirements on the same job may be less obvious because they are purely financial - reduced pumping, disposal, storage and regulatory costs. Because geotextile tubes are flexible in their adaptation and use, they can offer benefits in cost reduction far beyond more traditional methods available to a dredge operation. Not every job can use tubes for dewatering, and a bag test can provide the design engineer with information needed to assess which dewatering method will meet the needs of the client. Requirements vary from job to job. Effluent cleanliness is critical in some applications, while the dewatering rate is paramount in others. There is often a trade-off between the time required for a slurry to become "dry" and the amount of fine-grained solids that pass through the pores of the geotextile. Optimizing this trade-off has big implications for the dredging contractor, and in the case of geotextile tubes, requires matching the dredge's flow rate with the tube's discharge rate and volumetric capacity.