Abstract

This article reveals the change law of the head loss and critical deposition velocity during hydraulic transmission of a solid–liquid two-phase pipeline. This article also establishes a physical test model. A single variable is used to conduct the experimental research by changing the conditions of the pipeline flow rate, the sediment concentration, and the reverse slope degree. Based on an analysis of the test process, a new formula is proposed to determine the critical sedimentation rate of the pipeline that considers a change in the adverse slope. By analyzing the variation rule of the hydraulic slope of the pipeline sediment in different states and comparing the hydraulic slope of the horizontal pipeline and reverse pipeline in different states, different factors that influence head loss are revealed. Finally, the measured value of this test is compared with the Durand equation and the Worster equation. It was found that the measured value of this test was more similar to the Durand equation. This study not only provides theoretical support for sand removal in pipelines but also promotes sedimentation in reservoirs. Document type: Article

Abstract

SOCOTEC Spain, together with our partner GEM (Geotecnia y Exploraciones Marítimas), has been performing one of the largest geotechnical survey investigations in the development of new areas in the Port of Barcelona. This investigation includes multiple onshore and offshore tests including drilling and sampling, CPTU, and both in situ and laboratory testing. The CPTU (Cone Penetration Test with pore pressure measurement) is currently one of the most widely used in situ tests for soil characterization. Regarding the regularization of this test, all Standards specify the technical requirements of the equipment, the method of execution of the field test and the presentation of results and minimum corrections that have to be considered when performing and interpreting a CPTU. However, the current regulations do not refer to the methodology to be followed for the pre-drilling and/or re-drilling of the ground before a CPTU test, which is a common and operationally ‘standard’ procedure. In this sense, during the onsite research campaign, the results obtained in numerous onshore and offshore CPTU tests have been analyzed and, a variation in the pore pressure data recorded in the onshore CPTU tests associated with the pre-drilling and/or re-drilling operations has been identified. For this reason, the purpose of the paper is to highlight the need for a standardized procedure to execute this type of drilling operations and/or the necessary corrections to be taken into account during the interpretations of the results obtained in order to correct the anomalies associated with the injection of an artificial water flow.