CN104596891A - Method for determining plastic index and consistency state of natural cohesive soil - Google Patents
Method for determining plastic index and consistency state of natural cohesive soil Download PDFInfo
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- CN104596891A CN104596891A CN201510005357.3A CN201510005357A CN104596891A CN 104596891 A CN104596891 A CN 104596891A CN 201510005357 A CN201510005357 A CN 201510005357A CN 104596891 A CN104596891 A CN 104596891A
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Abstract
The invention relates to a method for determining the plastic index and the consistency state of natural cohesive soil. The method comprises the following steps: determining the relation between a water content w and a dropping depth h of the natural soft clay at a remodeling state by adopting a fall cone test, and making a remodeling state h-w curve graph; determining the fall cone depth h0 under the situation of natural water content w0 when the natural constitutive property is maintained; drawing a (w0, h0) point in the obtained curve graph; drawing a curve parallel to the remodeling state h-w curve from the (w0, h0) point, i.e. a natural state h-w curve, and finding the plastic limit water content w*p and the liquid limit water content w*L in the natural state h-w curve; calculating the plastic index and liquid index according to w*p and w*L, and evaluating the consistency state of the natural cohesive soil. Compared with the prior art, the result obtained in the method is more applicable to the natural soft clay with relatively high constitutive property, the consistency state of the natural soft clay can be more accurately evaluated, and accurate evidence can be provided for evaluating the mechanical properties of the natural cohesive soil.
Description
Technical field
The present invention relates to a kind of method measuring natural tack soil plasticity index and consistency state, belong to cohesive soil physico mechanical characteristic field tests in civil engineering work, Geotechnical Engineering, engineering geology field.
Background technology
The plasticity index of cohesive soil and consistency state are the basic and important foundations of assessment cohesive soil mechanical characteristic.Plastic limit water cut w
pwith liquid limit water cut w
lbe the important Atterberg limits of two of cohesive soil, two important plasticity index-plasticity index IP and liquidity index IL of cohesive soil can be calculated further according to two formula below on this basis,
IP=w
l-w
pformula 1
IL=(w
0-w
p)/IP formula 2
Wherein w
0it is the natural moisture content of soil.Liquidity index IL is the important indicator of the consistency state evaluating natural tack soil, according to the size of this index, cohesive soil can be divided into the states such as stream is moulded, softly to be moulded, plastic, hard plastic.
Traditional mensuration cohesive soil Atterberg limits (plastic limit water cut w
p) method comprise: (1) rubbing method measure soil plastic limit water cut w
p, adopt the Casa Grande formula liquid limit apparatus of Casa Grande invention to measure the liquid limit water cut w of soil
l.This is also the method for American-European countries's employing mostly at present.(2) fall cone method.The plastic limit water cut w of cohesive soil is determined according to the curve that is dark and water cut that falls falling into degree of depth drafting of circular cone in manipulated soil
p(it is 2mm that 76g cone falls to boring the degree of depth) and liquid limit water cut w
l(it is 17mm that 76g cone falls to boring the degree of depth).This method all widely uses in USSR (Union of Soviet Socialist Republics) and China.In these test methods, all need natural tack soil to reinvent the soil sample being prepared into and having different moisture content, the Atterberg limits w obtained
pand w
land plasticity index IP and IL can not reflect the impact of natural tack soil structure, the liquidity index IL therefore adopting these methods to obtain also can not make objective appraisal to the consistency state of natural tack soil.
Summary of the invention
Object of the present invention is exactly provide a kind of natural tack soil plasticity index and method of consistency state of measuring to overcome defect that above-mentioned prior art exists, the method can consider the natural structure of cohesive soil, the result obtained is more suitable for structural stronger natural soft clay, can evaluate the consistency state of natural soft clay more accurately, the assessment for natural tack soil mechanics characteristic provides foundation more accurately.
Object of the present invention can be achieved through the following technical solutions:
Measure a method for natural tack soil plasticity index and consistency state, the method comprises the following steps:
(1) adopt cone method to measure natural soft clay reinventing the water cut w under state and falling into degree of depth h relation, with logarithm lg (w) of water cut w for horizontal ordinate, to fall into logarithm lg (h) of degree of depth h for ordinate, make and reinvent state h-w curve map, when state h-w curve map is reinvented in making, get and be a little no less than 4 points, and get a little more, degree of accuracy is higher;
(2) natural moisture content is adopted to be w
0undisturbed soil sample, when keeping natural structure, using identical circular cone, measuring natural moisture content w
0fall to boring degree of depth h in situation
0; And by (w
0, h
0) in the curve map that obtains in step (1) of point-rendering;
(3) (the w that step (2) obtains is crossed
0, h
0) point, do the curve reinventing state h-w oriented parallel obtained with step (1), i.e. native state h-w curve, in native state h-w curve, find out water cut corresponding to h=2mm be plastic limit water cut w*
p, the water cut that h=17mm is corresponding is liquid limit water cut w*
l;
(4) according to the w* obtained
pwith w*
l, computational plasticity exponential sum liquidity index, adopts formula 1 and formula 2 computational plasticity exponential sum liquidity index:
Plasticity index IP=w*
l-w*
pformula 1;
Liquidity index IL=(w
0-w*
p)/IP formula 2;
Then the consistency state of natural tack soil is evaluated according to the liquidity index IL newly obtained.
When cone method of carrying out in step (1) and step (2) falling is measured, circular cone adopts 76g to bore, and cone angle is 30 °.
The method of traditional test cohesive soil Atterberg limits is (as rubbing method, butterfly liquid limit apparatus method, fall cone method) in the manipulated soil for having different moisture content used, can not consider the natural structure of cohesive soil, the division therefore for the consistency state of natural soft clay does not often meet actual conditions.The present invention proposes a kind of cone method that falls newly to measure natural tack soil plastic limit water cut w
pwith liquid limit water cut w
l, adopt new Atterberg limits to carry out computational plasticity index IP and liquidity index IL, evaluate consistency state states such as () stream is moulded, softly mould, plastic, hard plastics of natural tack soil.Compared with these classic methods, the method that the present invention proposes can consider the natural structure of cohesive soil, the result obtained is more suitable for structural stronger natural soft clay, can evaluate the consistency state of natural soft clay more accurately, the assessment for natural tack soil mechanics characteristic provides more accurate foundation.
Accompanying drawing explanation
Fig. 1 is for reinventing state h-w curve map.
Embodiment
Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.
Embodiment
Measure a method for natural tack soil plasticity index and consistency state, the method comprises the following steps:
(1) adopt cone method to measure natural soft clay reinventing the water cut w under state and falling into degree of depth h relation, with logarithm lg (w) of water cut w for horizontal ordinate, to fall into logarithm lg (h) of degree of depth h for ordinate, make and reinvent state h-w curve map, as shown in Figure 1, when state h-w curve map is reinvented in making, get and be a little no less than 4 points, and get a little more, degree of accuracy is higher;
(2) natural moisture content is adopted to be w
0undisturbed soil sample, when keeping natural structure, using identical circular cone, measuring natural moisture content w
0fall to boring degree of depth h in situation
0; And by (w
0, h
0) in the curve map that obtains in step (1) of point-rendering, the A point namely in Fig. 1;
(3) (the w that step (2) obtains is crossed
0, h
0) point, do the curve reinventing state h-w oriented parallel obtained with step (1), i.e. native state h-w curve, in native state h-w curve, find out water cut corresponding to h=2mm be plastic limit water cut w*
p, the water cut that h=17mm is corresponding is liquid limit water cut w*
l;
(4) according to the w* obtained
pwith w*
l, computational plasticity exponential sum liquidity index, adopts formula 1 and formula 2 computational plasticity exponential sum liquidity index:
Plasticity index IP=w*
l-w*
pformula 1;
Liquidity index IL=(w
0-w*
p)/IP formula 2;
Then the consistency state of natural tack soil is evaluated according to the liquidity index IL newly obtained.
When cone method of carrying out in step (1) and step (2) falling is measured, circular cone adopts 76g to bore, and cone angle is 30 °.
Above-mentioned is can understand and use invention for ease of those skilled in the art to the description of embodiment.Person skilled in the art obviously easily can make various amendment to these embodiments, and General Principle described herein is applied in other embodiments and need not through performing creative labour.Therefore, the invention is not restricted to above-described embodiment, those skilled in the art, according to announcement of the present invention, do not depart from improvement that scope makes and amendment all should within protection scope of the present invention.
Claims (5)
1. measure a method for natural tack soil plasticity index and consistency state, it is characterized in that, the method comprises the following steps:
(1) adopt cone method to measure natural soft clay reinventing the water cut w under state and falling into degree of depth h relation, and make and reinvent state h-w curve map;
(2) natural moisture content is adopted to be w
0undisturbed soil sample, when keeping natural structure, using identical circular cone, measuring natural moisture content w
0fall to boring degree of depth h in situation
0; And by (w
0, h
0) in the curve map that obtains in step (1) of point-rendering;
(3) (the w that step (2) obtains is crossed
0, h
0) point, do the curve reinventing state h-w oriented parallel obtained with step (1), i.e. native state h-w curve, in native state h-w curve, find out water cut corresponding to h=2mm be plastic limit water cut w*
p, the water cut that h=17mm is corresponding is liquid limit water cut w*
l;
(4) according to the w* obtained
pwith w*
l, computational plasticity exponential sum liquidity index, evaluates the consistency state of natural tack soil.
2. a kind of method measuring natural tack soil plasticity index and consistency state according to claim 1, it is characterized in that, in step (1), when state h-w curve map is reinvented in making, with logarithm lg (w) of water cut w for horizontal ordinate, to fall into logarithm lg (h) of degree of depth h for ordinate.
3. according to claim 1ly a kind ofly measure natural tack soil plasticity index and the method for consistency state, it is characterized in that, when cone method of carrying out in step (1) and step (2) falling is measured, circular cone adopts 76g to bore, and cone angle is 30 °.
4. a kind of method measuring natural tack soil plasticity index and consistency state according to claim 1, is characterized in that, in step (4), according to the w* recorded
pand w*
l, adopt formula 1 and formula 2 computational plasticity exponential sum liquidity index:
Plasticity index IP=w*
l-w*
pformula 1;
Liquidity index IL=(w
0-w*
p)/IP formula 2;
Then the consistency state of natural tack soil is evaluated according to the liquidity index IL newly obtained.
5. a kind of method measuring natural tack soil plasticity index and consistency state according to claim 1, is characterized in that, when state h-w curve map is reinvented in making in step (1), get and be a little no less than 4 points.
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| CN201510005357.3A CN104596891A (en) | 2015-01-04 | 2015-01-04 | Method for determining plastic index and consistency state of natural cohesive soil |
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| CN201510005357.3A CN104596891A (en) | 2015-01-04 | 2015-01-04 | Method for determining plastic index and consistency state of natural cohesive soil |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110904948A (en) * | 2019-10-22 | 2020-03-24 | 长沙理工大学 | Emergency compaction construction method for soft plastic modified soil replacement foundation |
| CN113567303A (en) * | 2021-07-20 | 2021-10-29 | 深圳市市政工程总公司 | Method for measuring liquid limit, plastic limit and plasticity index of dredged sludge |
| CN115166197A (en) * | 2022-06-09 | 2022-10-11 | 中南大学 | Method for determining liquid limit and plastic limit of high-liquid limit soil containing breccia and sand |
| CN116698670A (en) * | 2022-12-12 | 2023-09-05 | 青岛理工大学 | Soil classification method for realizing agglomerate content evaluation |
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| CN2290055Y (en) * | 1996-12-03 | 1998-09-02 | 湖南省交通科学研究所 | Interlligence soil liquid plastic limit combination measuring instrument |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110904948A (en) * | 2019-10-22 | 2020-03-24 | 长沙理工大学 | Emergency compaction construction method for soft plastic modified soil replacement foundation |
| CN110904948B (en) * | 2019-10-22 | 2022-05-06 | 长沙理工大学 | Emergency compaction construction method for soft plastic modified soil replacement foundation |
| CN113567303A (en) * | 2021-07-20 | 2021-10-29 | 深圳市市政工程总公司 | Method for measuring liquid limit, plastic limit and plasticity index of dredged sludge |
| CN115166197A (en) * | 2022-06-09 | 2022-10-11 | 中南大学 | Method for determining liquid limit and plastic limit of high-liquid limit soil containing breccia and sand |
| CN115166197B (en) * | 2022-06-09 | 2023-11-03 | 中南大学 | Method for determining high liquid limit soil liquid limit and plastic limit of gravel and sand |
| CN116698670A (en) * | 2022-12-12 | 2023-09-05 | 青岛理工大学 | Soil classification method for realizing agglomerate content evaluation |
| CN116698670B (en) * | 2022-12-12 | 2024-01-26 | 青岛理工大学 | Soil classification method for realizing agglomerate content evaluation |
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