Determination method for liquid limit, plastic limit and plastic index of dredged sludge

Abstract

The invention relates to the technical field of environmental engineering, and discloses a determination method for a liquid limit, a plastic limit and a plastic index of dredged sludge. The determination method comprises the following steps of: S1, carrying out sampling; S2, placing a sample cup containing a soil sample with a certain water content on a base of a combined tester, and adjusting a lifting base to enable a conical tip of a cone to be in contact with and aligned with the top surface of the soil sample; S3, allowing the cone to freely fall into the soil sample for 5 s, recording the sinking depth of the cone, taking 10 g of the soil sample near the cone, and determining the water content of the soil sample; S4, taking sample cups with different water contents, repeating the step S2 and the step S3, and measuring multiple groups of numerical values; S5, drawing a relation curve in the double logarithmic coordinates by taking the water content as the abscissa and the cone sinking depth as the ordinate; S6, looking up the water content corresponding to the sinking depth of 17 mm on a relational graph as the liquid limit, the water content corresponding to the sinking depth of 2 mm as the plastic limit, and the difference between the liquid limit and the plastic limit as the plastic index; and S7, verifying the measured plastic water content by using a rolling and rubbing method. The determination method synchronously determines multiple groups of performances of the sludge, is convenient and fast, and can improve the accuracy of the determination result.

Description

technical field [0001] The invention relates to the technical field of environmental engineering, in particular to a method for measuring liquid limit, plastic limit and plasticity index of dredged silt. Background technique [0002] The water flow received by urban rivers includes urban surface runoff, domestic sewage and industrial wastewater. The particulate matter and dissolved substances carried in these water flows will settle under certain hydraulic conditions, chemical and biological effects, and turn into water sediments. . In addition, because of the low permeability and roughness of the underlying surface of the urban catchment area, the runoff intensity is increased, making the ground sediment easily entrained by the runoff. The runoff mainly flows into the water body in the form of pipeline flow, and lacks the filtering effect of the vegetation belt on the particulate matter in the runoff, so the sediment generation rate of urban river water bodies is higher th...

AI Technical Summary

Problems solved by technology

However, the existing measurement methods for its parameters rely on increasing the number of tests to avoid test errors, and there are still certain large errors in the measurement results of the tests, which affect the accuracy of the measurement results; and the existing measurement methods are cumbersome and difficult to measure. kind of hard

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