阅读说明：本技术 疏浚淤泥的液限、塑限及塑性指数测定方法 (Method for measuring liquid limit, plastic limit and plasticity index of dredged sludge ) 是由 陈俭 罗燕山 梁雄威 林璇 钟原 张伯发 宋长颖 于 2021-07-20 设计创作，主要内容包括：本发明涉及环境工程技术领域,公开了疏浚淤泥的液限、塑限及塑性指数测定方法,包括以下步骤：S1:取样；S2：将含有一定含水率土样的试样杯放置于联合测定仪底座上,调节升降座使圆锥仪的锥尖接触对准土样顶面；S3：令圆锥自由下落坠入土样中5s后记录圆锥下沉深度,取圆锥附近10g土样测定其含水率；S4：取不同含水量的试样杯重复S2和S3两步测得多组数值；S5：以含水率为横坐标,圆锥下沉深度为纵坐标,在双对数坐标中绘制关系曲线；S6：在关系图上查得下沉深度17mm所对应的含水率为液限,2mm所对应的含水率为塑限,液塑限之差为塑性指数；S7：使用滚搓法验证上述测得的塑性含水率。该方法同步测定淤泥多组性能,方便快捷,能够提高测定结果的准确性。(The invention relates to the technical field of environmental engineering, and discloses a method for measuring liquid limit, plastic limit and plasticity index of dredged sludge, which comprises the following steps: s1, sampling; s2: placing a sample cup containing a soil sample with certain water content on a base of the joint determinator, and adjusting a lifting seat to enable a cone tip of a cone analyzer to be in contact with and aligned with the top surface of the soil sample; s3: the cone is allowed to fall freely into the soil sample for 5s, then the sinking depth of the cone is recorded, and 10g of soil sample near the cone is taken to measure the water content; s4: taking sample cups with different water contents, repeating the steps of S2 and S3 to obtain a plurality of groups of values; s5: drawing a relation curve in a double logarithmic coordinate by taking the water content as a horizontal coordinate and the cone sinking depth as a vertical coordinate; s6: checking the relation graph to obtain that the water content corresponding to the sinking depth of 17mm is a liquid limit, the water content corresponding to 2mm is a plastic limit, and the difference of the liquid-plastic limits is a plasticity index; s7: and verifying the measured plastic water content by using a rolling and rubbing method. The method for synchronously measuring the multiple groups of performances of the sludge is convenient and quick, and can improve the accuracy of the measurement result.)

1. The method for measuring the liquid limit, plastic limit and plasticity index of the dredged sludge is characterized by comprising the following steps:

s1, sampling, namely taking a plurality of representative soil samples and processing the soil samples;

s2: placing a sample cup containing a pasty soil sample with certain water content on a base of a photoelectric combined determinator, and then adjusting a lifting seat to enable a cone tip of a cone instrument to be in contact with a horizontal sample surface of the soil sample;

s3: starting a cone falling switch, enabling a cone of the photoelectric combined measuring instrument to fall freely into a soil sample, immediately recording the sinking depth (penetration amount/h) of the cone after 5s, and then taking a soil sample of 10g near the cone to measure the water content of the soil sample;

s4: taking sample cups with different water contents, repeating the steps of S2 and S3, and measuring penetration values corresponding to 3 water contents;

s5: drawing a relation curve in a double logarithmic coordinate by taking the water content as a horizontal coordinate and the cone sinking depth as a vertical coordinate;

s6: on a relation graph of the cone sinking depth and the water content, the corresponding water content is checked to be a liquid limit when the sinking depth is 17mm, the corresponding water content is checked to be a plastic limit when the sinking depth is 2mm, the corresponding water content is expressed by percentage, and the difference of the liquid-plastic limits is a plasticity index;

s7: and verifying the measured plastic water content by using a rolling and rubbing method, and enhancing the accuracy of the test result.

2. The dredged sludge liquid limit, plastic limit, and plasticity index determination method of claim 1, wherein: in the step S1, the soil sample processing includes the steps of:

s101: taking a soil sample in a representative area, carrying out natural air drying for 3-6 months, immediately transporting the soil sample to a laboratory, and keeping the soil sample in a refrigerator at 4 ℃ in a dark place;

s102: taking a proper amount of soil particles or impurities with the particle size of more than 0.5mm after air drying, crushing the soil particles or the impurities on a rubber plate by using a pestle with a rubber head or a wood bar, and then sieving the crushed soil particles or the impurities by using a square-hole sieve with the sieve holes of 0.5mm to remove impurities in the soil sample;

s103: measuring 200g of soil sample by using an electronic scale for multiple times, respectively putting the soil sample into three sample cups marked with a, b and c, adding different amounts of distilled water into three vessels, and stirring and blending the three vessels into a compact and uniform paste by using a glass rod;

s104: after the soil sample is stirred and blended into a dense and uniform paste, a sealing film is sealed at the port of the vessel, and the soil sample is sealed and stored for more than 18 hours by using the sealing film for use.

3. The dredged sludge liquid limit, plastic limit, and plasticity index determination method of claim 1, wherein: before the cone in the S3 falls freely, a layer of vaseline should be uniformly coated on the outer wall of the tip end of the cone, and before the soil sample near the cone after falling is taken to measure the water content, a scoop should be used to remove the vaseline soil for testing.

4. The dredged sludge liquid limit, plastic limit, and plasticity index determination method of claim 1, wherein: when the relation curve is drawn in the step S5, three points corresponding to the measured 3 moisture contents are connected to form a straight line, and when the three points are not in the straight line, one point with high moisture content is connected to two other points to form two straight lines.

5. The dredged sludge liquid limit, plastic limit, and plasticity index determination method of claim 1, wherein: and in the S6, corresponding water content is obtained by checking the cone sinking depth of 2mm, when the difference value of the water content is less than 2%, the average value of the water content of the two points is connected with a point with high water content to form a line, and when the difference value of the two water content is more than or equal to 2%, the experiment is carried out in a supplementary mode.

6. The dredged sludge liquid limit, plastic limit, and plasticity index determination method of claim 1, wherein: the operation steps of the rolling and rubbing method verification test in the S7 are as follows;

s701: weighing 100g of a representative soil sample with a sieve of 0.5mm by using an electronic scale, placing the soil sample in a soil containing vessel, adding pure water, uniformly stirring, and wetting overnight;

s702, kneading the prepared sample in hands until the sample is not sticky, and then kneading the sample to be flat, wherein when the soil sample has cracks, the water content is close to plasticity;

s703: weighing 8-10g of a sample with the water content close to the plastic water content, holding the sample into an oval shape by hands, and then placing the oval in a ground glass plate, rolling and rubbing the oval on a palm to form a soil strip;

s704: when the soil strips are twisted into 3mm, cracks are generated and break, the water content of the sample is shown to reach the plastic water content, when the soil strips are twisted into 3mm, the cracks are not generated or the soil strips start to break when the diameter of the soil strips is larger than 3mm, and the soil strips are sampled again for testing;

s705: measuring 3-5g of a soil strip with a crack and a diameter of 3mm by using a caliper with a division value of 0.02mm, and measuring the water content of the soil strip.

7. The dredged sludge liquid limit, plastic limit, and plasticity index determination method of claim 6, wherein: and the water content of the soil sampled and purified in the step S701 is consistent with that of the sample prepared in the step S103, and the result of the determination of the water content is used for comparing the plastic water content of the sample measured by the combined measuring instrument.

8. The dredged sludge liquid limit, plastic limit, and plasticity index determination method of claim 6, wherein: and S701, adding water and blending to obtain a soil sample, placing the soil sample in a vacuum environment for storage, and sealing the port of the soil container by using a sealing film.

9. The dredged sludge liquid limit, plastic limit, and plasticity index determination method of claim 6, wherein: in the step S703, the pressure of the palm is uniformly applied to the soil strips when the soil strips are rolled and kneaded, so that the soil strips cannot roll on the ground glass without force, the soil strips cannot have a hollow phenomenon, and the length of the soil strips is not larger than the width of the palm.

10. The dredged sludge liquid limit, plastic limit, and plasticity index determination method of claim 6, wherein: in the S704, the rolling method plastic limit test should be performed by parallel measurement of two sides, and the difference between the two measured values should not be greater than 1%, and when the WL is greater than or equal to 40%, it should not be greater than 2%.

Technical Field

The invention relates to the technical field of environmental engineering, in particular to a method for measuring a liquid limit, a plastic limit and a plasticity index of dredged sludge.

Background

The water flows received by the urban river include urban surface runoff, domestic sewage and industrial wastewater, and granular substances and soluble substances carried in the water flows can be settled under certain hydraulic conditions and chemical and biological actions and are converted into water body sediments. And because the water permeability and the roughness of the underlying surface of the urban catchment area are lower, the runoff strength is increased, and the ground sediments are easy to be entrained by runoff. Runoff mainly sinks into the water body in a pipeline flow mode, and the filtering effect of a vegetation zone on particulate matters in the runoff is lacked, so that the generation rate of the urban riverway water body sediments is higher than that of the water body in a natural ecological system, and the riverway waterpower, hydrology conditions and navigation capability are seriously deteriorated. In the process of forming water body sediments, pollutants such as heavy metals and POPs entering a water body are gathered through a series of physical and chemical actions such as adsorption, complexation and chemical reaction, and when the environmental conditions of the interface of water and the sediments are changed, the pollutants gathered in the sediments can be released again to become endogenous pollution of the water environment, so that serious threats are caused to the ecological environment of the water body and the smoothness of water flow, and river and lake dredging becomes an indispensable important link in the comprehensive treatment of the water environment.

A large amount of sludge is generated after the river channel is dredged, the sludge is generally transported to be used as roadbed engineering backfill soil, airport roadbed backfill soil, landscaping soil and the like after being solidified and modified, the sludge is changed into valuable materials to be used as available resources, but mechanical performance parameters such as liquid limit, plastic limit, plasticity index and the like of the solidified sludge can be used to ensure the safety quality of engineering after meeting the standards specified by the national law, and therefore performance measurement needs to be carried out on the solidified and modified sludge. However, the existing parameter measuring method avoids the test error by increasing the test times, and the measuring result of the test still has certain larger error, which affects the accuracy of the measuring result; moreover, the conventional measurement method is complicated and troublesome in measurement.

Therefore, we propose a method for measuring the liquid limit, plastic limit and plasticity index of the dredged sludge.

Disclosure of Invention

The invention aims to provide a method for measuring the liquid limit, the plastic limit and the plasticity index of dredged sludge, which can simultaneously measure a plurality of performance parameters of solidified sludge, is convenient and quick, and is also provided with a subsequent verification contrast test, so that the measured values of the verification contrast test are compared and evaluated to obtain the sludge performance parameters, the accuracy of the test result is improved, and the problems brought forward in the background are solved.

In order to achieve the purpose, the invention provides the following technical scheme: the method for measuring the liquid limit, plastic limit and plasticity index of the dredged sludge comprises the following steps:

s1, sampling, namely taking a plurality of representative soil samples and processing the soil samples;

s2: placing a sample cup containing a pasty soil sample with certain water content on a base of a photoelectric combined determinator, and then adjusting a lifting seat to enable a cone tip of a cone instrument to be in contact with a horizontal sample surface of the soil sample;

s3: starting a cone falling switch, enabling a cone of the photoelectric combined measuring instrument to fall freely into a soil sample, immediately recording the sinking depth (penetration amount/h) of the cone after 5s, and then taking a soil sample of 10g near the cone to measure the water content of the soil sample;

s4: taking sample cups with different water contents, repeating the steps of S2 and S3, and measuring penetration values corresponding to 3 water contents;

s5: drawing a relation curve in a double logarithmic coordinate by taking the water content as a horizontal coordinate and the cone sinking depth as a vertical coordinate;

s6: on a relation graph of the cone sinking depth and the water content, the corresponding water content is checked to be a liquid limit when the sinking depth is 17mm, the corresponding water content is checked to be a plastic limit when the sinking depth is 2mm, the corresponding water content is expressed by percentage, and the difference of the liquid-plastic limits is a plasticity index;

s7: and verifying the measured plastic water content by using a rolling and rubbing method, and enhancing the accuracy of the test result.

Further, in the step S1, the soil sample processing includes the steps of:

s101: taking a soil sample in a representative area, carrying out natural air drying for 3-6 months, immediately transporting the soil sample to a laboratory, and keeping the soil sample in a refrigerator at 4 ℃ in a dark place;

s102: taking a proper amount of soil particles or impurities with the particle size of more than 0.5mm after air drying, crushing the soil particles or the impurities on a rubber plate by using a pestle with a rubber head or a wood bar, and then sieving the crushed soil particles or the impurities by using a square-hole sieve with the sieve holes of 0.5mm to remove impurities in the soil sample;

s103: measuring 200g of soil sample by using an electronic scale for multiple times, respectively putting the soil sample into three sample cups marked with a, b and c, adding different amounts of distilled water into three vessels, and stirring and blending the three vessels into a compact and uniform paste by using a glass rod;

s104: after the soil sample is stirred and blended into a dense and uniform paste, a sealing film is sealed at the port of the vessel, and the soil sample is sealed and stored for more than 18 hours by using the sealing film for use.

Further, before the cone in the S3 falls freely, a layer of vaseline should be evenly coated on the outer wall of the tip end of the cone, and after the cone falls down, a scoop should be used for removing the vaseline soil for testing before measuring the water content of the soil sample near the cone.

Further, when the relation curve is drawn in S5, three points corresponding to the measured 3 water contents are connected to form a straight line, and when the three points are not in the straight line, one point with high water content is connected to two other points to form two straight lines.

Further, in the step S6, a corresponding moisture content is obtained at a position where the cone sinking depth is 2mm, when the difference between the moisture content is less than 2%, the average value of the moisture content of the two points and the point with high moisture content are connected to form a line, and when the difference between the two moisture content is greater than or equal to 2%, the experiment should be performed in a supplementary manner.

Further, the operation steps of the rolling and rubbing method verification test in S7 are as follows;

s701: weighing 100g of a representative soil sample with a sieve of 0.5mm by using an electronic scale, placing the soil sample in a soil containing vessel, adding pure water, uniformly stirring, and wetting overnight;

s702, kneading the prepared sample in hands until the sample is not sticky, and then kneading the sample to be flat, wherein when the soil sample has cracks, the water content is close to plasticity;

s703: weighing 8-10g of a sample with the water content close to the plastic water content, holding the sample into an oval shape by hands, and then placing the oval in a ground glass plate, rolling and rubbing the oval on a palm to form a soil strip;

s704: when the soil strips are twisted into 3mm, cracks are generated and break, the water content of the sample is shown to reach the plastic water content, when the soil strips are twisted into 3mm, the cracks are not generated or the soil strips start to break when the diameter of the soil strips is larger than 3mm, and the soil strips are sampled again for testing;

s705: measuring 3-5g of a soil strip with a crack and a diameter of 3mm by using a caliper with a division value of 0.02mm, and measuring the water content of the soil strip.

Further, the water content of the soil sampled and purified in the step S701 is consistent with the water content of the sample prepared in the step S103, and the result of the determination of the water content is used for comparing the plastic water content of the sample measured by the joint measuring instrument.

Further, the soil sample mixed with water in the step S701 is placed in a vacuum environment for storage, and a sealing film is used for sealing the port of the soil container.

Further, the pressure of the palm is uniformly applied to the soil strips when the soil strips are rolled and kneaded in the step S703, so that the soil strips cannot roll on the ground glass without force, the soil strips cannot have a hollow phenomenon, and the length of the soil strips is not larger than the width of the palm.

Further, in the S704, the rolling method plastic limit test should perform parallel measurement on two sides, where the difference between the two measured values should not be greater than 1%, and when the WL is greater than or equal to 40%, it should not be greater than 2%.

The invention provides a method for measuring liquid limit, plastic limit and plasticity index of dredged sludge, which comprises the steps of adopting a cone instrument free falling body of a photoelectric combined measuring instrument to sink into a pasty soil sample with measurement for 5s, recording the penetration amount, taking a soil sample of 10g near the cone to measure the water content of the soil sample, repeatedly measuring different groups of water content samples by variable to obtain multiple groups of data, drawing a relation curve in a double logarithmic coordinate by taking the water content as a horizontal coordinate and the sinking depth of the cone as a vertical coordinate, checking the relation curve on the relation curve, wherein the water content corresponding to the sinking depth of 17mm is the liquid limit, the water content corresponding to 2mm is the plastic limit, and the difference between the liquid and plastic limits is the plasticity index.

Drawings

FIG. 1 is an overall flow chart of the method for determining the liquid limit, plastic limit and plasticity index of dredged sludge according to the invention;

FIG. 2 is a flow chart of the soil sample treatment in S1 of the method for measuring liquid limit, plastic limit and plasticity index of dredged sludge according to the present invention;

FIG. 3 is a table of combined measurement considerations for the determination of liquid limit, plastic limit and plasticity index of dredged sludge according to the present invention;

FIG. 4 is a table of mechanical properties of a consolidated soil sample measured in combination by the method for measuring liquid limit, plastic limit and plasticity index of dredged sludge according to the present invention;

FIG. 5 is a flow chart of the verification of the tumbling method in S7 of the method for measuring the liquid limit, the plastic limit and the plasticity index of the dredged sludge according to the invention;

FIG. 6 is a table of rolling verification notes for the method of determining liquid limit, plastic limit and plasticity index of dredged sludge according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, 3 and 4, a method for determining a liquid limit, a plastic limit and a plasticity index of dredged sludge includes the following steps:

sampling, namely taking a plurality of representative soil samples and processing the soil samples;

step two: placing a sample cup containing a pasty soil sample with certain water content on a base of a photoelectric combined determinator, and then adjusting a lifting seat to enable a cone tip of a cone instrument to be in contact with a horizontal sample surface of the soil sample;

step three: starting a cone falling switch, enabling a cone of the photoelectric combined measuring instrument to fall freely into a soil sample, immediately recording the sinking depth (penetration amount/h) of the cone after 5s, and then taking a soil sample of 10g near the cone to measure the water content of the soil sample;

step four: taking sample cups with different water contents, repeating the second step and the third step, and measuring penetration values corresponding to 3 water contents in total;

step five: drawing a relation curve in a double logarithmic coordinate by taking the water content as a horizontal coordinate and the cone sinking depth as a vertical coordinate;

step six: on a relation graph of the cone sinking depth and the water content, the corresponding water content is checked to be a liquid limit when the sinking depth is 17mm, the corresponding water content is checked to be a plastic limit when the sinking depth is 2mm, the corresponding water content is expressed by percentage, and the difference of the liquid-plastic limits is a plasticity index;

step seven: and verifying the measured plastic water content by using a rolling and rubbing method, and enhancing the accuracy of the test result.

Before the cone in the third step falls freely, a layer of vaseline is uniformly coated on the outer wall of the tip end of the cone, and before the soil sample near the fallen cone is taken to measure the water content, a scoop is used for removing the vaseline soil for testing; when drawing a relation curve in the fifth step, connecting three points corresponding to the measured 3 water contents into a straight line, and connecting one point with the other two points into two straight lines through one point with high water content when the three points are not in the straight line; and step six, checking a position with the cone sinking depth of 2mm to obtain corresponding water content, connecting an average value of the water content of the two points and a point with high water content into a line when the difference value of the water content is less than 2%, and performing a supplementary experiment when the difference value of the two water content is greater than or equal to 2%.

Referring to fig. 1 and 2, in the first step, the soil sample treatment includes the following steps:

s101: taking a soil sample in a representative area, carrying out natural air drying for 3-6 months, immediately transporting the soil sample to a laboratory, and keeping the soil sample in a refrigerator at 4 ℃ in a dark place;

s102: taking a proper amount of soil particles or impurities with the particle size of more than 0.5mm after air drying, crushing the soil particles or the impurities on a rubber plate by using a pestle with a rubber head or a wood bar, and then sieving the crushed soil particles or the impurities by using a square-hole sieve with the sieve holes of 0.5mm to remove impurities in the soil sample;

s103: measuring 200g of soil sample by using an electronic scale for multiple times, respectively putting the soil sample into three sample cups marked with a, b and c, adding different amounts of distilled water into three vessels, and stirring and blending the three vessels into a compact and uniform paste by using a glass rod;

s104: after the soil sample is stirred and blended into a dense and uniform paste, a sealing film is sealed at the port of the vessel, and the soil sample is sealed and stored for more than 18 hours by using the sealing film for use.

Referring to fig. 1, 5 and 6, the operation steps of the rolling and rubbing verification test in step seven are as follows;

s701: weighing 100g of a representative soil sample with a sieve of 0.5mm by using an electronic scale, placing the soil sample in a soil containing vessel, adding pure water, uniformly stirring, and wetting overnight;

s702, kneading the prepared sample in hands until the sample is not sticky, and then kneading the sample to be flat, wherein when the soil sample has cracks, the water content is close to plasticity;

s703: weighing 8-10g of a sample with the water content close to the plastic water content, holding the sample into an oval shape by hands, and then placing the oval in a ground glass plate, rolling and rubbing the oval on a palm to form a soil strip;

s704: when the soil strips are twisted into 3mm, cracks are generated and break, the water content of the sample is shown to reach the plastic water content, when the soil strips are twisted into 3mm, the cracks are not generated or the soil strips start to break when the diameter of the soil strips is larger than 3mm, and the soil strips are sampled again for testing;

s705: measuring 3-5g of a soil strip with a crack and a diameter of 3mm by using a caliper with a division value of 0.02mm, and measuring the water content of the soil strip.

The water content of the soil sampled and purified in the S701 to prepare the sample is kept consistent with that of the sample prepared in the S103 respectively, the water content determination result is used for comparing the plastic water content of the sample measured by the joint determinator, the soil sample blended by adding water is placed in a vacuum environment for storage, and the port of the soil container is sealed by a sealing film; in the S703, the pressure of the palm is uniformly applied to the soil strips when the soil strips are rolled and kneaded, so that the soil strips cannot roll on the ground glass without force, the soil strips cannot have a hollow phenomenon, and the length of the soil strips is not larger than the width of the palm; in S704, the rolling method plastic limit test should be performed by parallel measurement of two sides, and the difference between the two measured values should not be greater than 1%, and when the WL is greater than or equal to 40%, it should not be greater than 2%.

In summary, the following steps: the invention provides a method for measuring liquid limit, plastic limit and plastic index of dredged sludge, which comprises the steps of adopting a cone instrument free falling body of a photoelectric combined measuring instrument to sink into a pasty soil sample with a measuring belt for 5s, then recording the penetration amount, taking a soil sample of 10g near the cone to measure the water content of the soil sample, repeatedly measuring different groups of water content samples by variable for multiple times to obtain multiple groups of data, drawing a relation curve in a double logarithmic coordinate by taking the water content as a horizontal coordinate and the sinking depth of the cone as a vertical coordinate, checking the water content corresponding to the sinking depth of 17mm on the relation curve as the liquid limit, the water content corresponding to 2mm as the plastic limit and the difference between the liquid and the plastic limits as the plastic index, and can rapidly and synchronously measure the specific performance parameters of the liquid limit, the plastic limit and the plastic index after sludge is solidified, thereby being convenient and rapid; after concrete performance parameters of liquid limit, plastic limit and plasticity index of the solidified sludge are measured, a plurality of groups of sample soil strips with corresponding water content are prepared by adopting a rolling rubbing method, a plurality of groups of parallel tests are carried out by utilizing a water content value measured by the sample soil strips which generate cracks and start to break when being rubbed into a size of 3mm, the results are compared with the soil sample plastic limit water content value measured before, the accuracy of the measured liquid limit, plastic limit and plasticity index results is flatly judged, and the accuracy of test data is enhanced; the method is characterized in that related sludge performance parameters are measured in a mode of combining tests and drawing, and an operator is required to have good drawing capability on the premise of requiring an in-person manual test, so that the manual capability and the drawing capability of the tester can be well cultivated.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention provides a method for measuring liquid limit, plastic limit and plasticity index of dredged sludge, which comprises the steps of adopting a cone instrument free falling body of a photoelectric combined measuring instrument to sink into a pasty soil sample with measurement for 5s, recording the penetration amount, taking a soil sample of 10g near the cone to measure the water content of the soil sample, repeatedly measuring different groups of water content samples by variable to obtain multiple groups of data, drawing a relation curve in a double logarithmic coordinate by taking the water content as a horizontal coordinate and the sinking depth of the cone as a vertical coordinate, checking the relation curve on the relation curve, wherein the water content corresponding to the sinking depth of 17mm is the liquid limit, the water content corresponding to 2mm is the plastic limit, and the difference between the liquid and plastic limits is the plasticity index.

2. The method for measuring the liquid limit, the plastic limit and the plasticity index of the dredged sludge comprises the steps of measuring specific performance parameters of the liquid limit, the plastic limit and the plasticity index after the sludge is solidified, preparing a plurality of groups of sample soil strips with corresponding water contents by adopting a rolling and rubbing method, comparing the result with the previously measured value of the plastic limit water content of a soil sample after a plurality of groups of parallel tests are carried out by utilizing the value of the water content measured by the sample soil strips which generate cracks and start to fracture when being rubbed into a size of 3mm, and flatly judging the accuracy of the measured liquid limit, plastic limit and plasticity index results to enhance the accuracy of test data.

3. The method for measuring the liquid limit, the plastic limit and the plasticity index of the dredged sludge, provided by the invention, measures related sludge performance parameters by adopting a mode of combining tests and drawing, and needs an operator to have good drawing capability on the premise of requiring an in-person manual test, so that the method can be used for well culturing the manual capability and the drawing and painting capability of the tester.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.