CN106408211B - A method of differentiating buried saturated sand earthquake liquefaction - Google Patents
A method of differentiating buried saturated sand earthquake liquefaction Download PDFInfo
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Abstract
A method of differentiating buried saturated sand earthquake liquefaction, including six steps, step 1: determining buried saturation layer of sand different location, the Standard penetration test blow count at different depth；Step 2: the earthquake cyclic shear stress ratio CSR of buried saturation layer of sand various criterion penetration test point is determined；Step 3: determine that standard penetration test (SPT) is covered with efficacy on actually critical using the method for hypothesis testing；Step 4: the normalization Standard penetration test blow count of standard penetration test (SPT) point at acquisition different location, different depth；Step 5: Shear stress ratio of liquefaction CRR is determined7.5；Step 6: comparison earthquake motion shear stress ratio CSR and Shear stress ratio of liquefaction CRR7.5, carry out seismic liquefaction evaluation.The present invention can overcome existing specification Plays blow number liquefaction Judgment Method to may not apply to the defect of 20m or less soil layer, can expand existing Standard penetration test blow count liquefaction Judgment Method and be applied to buried saturated sand seismic liquefaction evaluation.
Description
Technical field
The invention belongs to geotechnological quake-resistant safeties to evaluate field, be related to a kind of method for differentiating buried saturated sand earthquake liquefaction.
Background technique
80% or more China's hydroelectric resources is distributed in the west area that seismic activity is frequent and intensity is big, and this area riverbed is big
There is deep covering layer, sand etc. is commonly present in deep covering layer may liquefied soil layer or lenticular body under geological process more.
With the implementation of strategy to develop western regions, more and more earth-rock works will be built on deep covering layer, in deep covering layer
The stability of sand or its lenticular body under geological process is to be related to the critical issue of engineering safety and feasibility, but buried saturation
Sand Liquefaction differentiation be at present academicly with the difficulties in engineering.Standard penetration test (SPT) is that widely used scene is former
Bit test method, based on standard penetration test (SPT) differentiate the method for foundation soil liquefaction possibility in engineering using very extensive, but
Standard penetration test (SPT) liquefaction Judgment Method in existing specification, applicable foundation soil depth (are above covered with efficacy substantially in 20m
Upper is 200kPa) within, the buried saturated sand earthquake liquefaction more than 20m (being above covered with efficacy substantially 200kPa) is sentenced
Not, existing method is not applicable.
Summary of the invention
A kind of purpose for the method for differentiating buried saturated sand earthquake liquefaction of the present invention will be based on standard penetration test (SPT)
Shallow soil seismic liquefaction evaluation method, which is expanded, is applied to buried saturated sand seismic liquefaction evaluation；The prior art is only applicable to shallow-layer
Sand Liquefaction differentiate, applied to be above covered with efficacy be more than 20m liquefaction of soil mass differentiate actually lack it is enough according to
According to.
To achieve the above object, the present invention the following technical schemes are provided:
A method of buried saturated sand earthquake liquefaction is differentiated, for being more than the buried saturated sand earthquake liquefaction of 20m
Differentiate, which comprises the following steps:
Step 1: at the scene, according to specification to being more than the buried sandy soils of big thickness of 20m in different parts, different depth
Place carries out standard penetration test (SPT), obtain different location, at different depth layer of sand Standard penetration test blow count N '；
Step 2: calculating standard penetration test (SPT) under certain seismic acceleration according to standard penetration test (SPT) point stress condition and surveying
Seismic earthquake cyclic shear stress ratio CSR at pilot:
In formula: τav- seismic dynamic shear stress；amaxSurface ground motion acceleration peak；G- gravity accelerates
Degree；σv0Vertical total stress；σ'v0Above it is covered with efficacy；γd- stress Stiffness degradation coefficient；
Step 3: determining that covering layer soil body standard penetration test (SPT) is covered with efficacy σ ' on actually criticalcr, specific steps are such as
Under:
A, assume covering layer soil body standard penetration test (SPT) it is critical on be covered with efficacy be σ 'a；
B, efficacy σ ' will be covered on each standard penetration test (SPT) pointv0With hypothesis it is critical on be covered with efficacy σ 'aCompared
Compared with if σ 'v0≤σ'a, then depth corresponding actual measurement Standard penetration test blow count N ' in testing site is corrected to formula (2) and is covered with effect
Under the conditions of stress is the standard stress of 100kPa, normalization Standard penetration test blow count is (N1)60；
Wherein, PaFor normal atmospheric pressure；
C, normal distribution is carried out to the Standard penetration test blow count sample data being corrected under 100kPa using hypothesis testing method
It examines, judges to be covered with efficacy σ ' on empirical thresholdaWhether lower normalization Standard penetration test blow count sample data meets normal distribution,
If inspection result meets normal distribution, illustrate to be covered with efficacy σ ' in the hypothesisaIt, can within the scope of application of formula (2)
Continue to increase assume it is critical on be covered with efficacy, continue following steps；
D, increase assume it is critical on be covered with efficacy to σ 'a+ Δ σ, repeats B to C, to the standard being corrected under 100kPa
Blow number sample data carry out normal distribution-test, until it is assumed that it is critical on be covered with efficacy under, to normalization standard
Blow number sample data inspection result do not meet normal distribution and assume it is critical on be covered with efficacy and reach 800kPa or more
Until；
E, it is covered under efficacy according on above-mentioned each empirical threshold, to the Standard penetration test blow count sample being corrected under 100kPa
Data progress hypothesis testing is covered with efficacy σ ' on the coefficient of skewness, coefficient of kurtosis and empirical threshold as a result, drawingaRelationship it is bent
Line can meet U < U both in figure simultaneously0.05=1.96 cannot meet U < U to the two simultaneously0.05=1.96 separation is corresponding
It is to be covered with efficacy σ ' on reality is critical that efficacy is covered on empirical thresholdcr；
Step 4: using formula (3) by buried saturation layer of sand different location, the school Standard penetration test blow count N ' at different depth
It just arrives under the conditions of the standard stress of 100kPa, the normalization standard of standard penetration test (SPT) point at acquisition different location, different depth
Blow number (N1)60:
Step 5: using the normalization standard of standard penetration test (SPT) point at the determining different location of step 4, different depth
Blow number (N1)60, according to standard penetration test (SPT) point pair at the buried saturated sand different location of formula (4) calculating, different depth
The Shear stress ratio of liquefaction CRR answered7.5:
Step 6: by Shear stress ratio of liquefaction CRR7.5Be compared with earthquake cyclic shear stress ratio CSR, when CSR >=
CRR7.5, the soil body liquefies；As CSR < CRR7.5, the soil body do not liquefy.
It is further preferred that the step 3 is normalized to 100kPa phase to being covered under the conditions of efficacy on the empirical threshold
Hypothesis testing is carried out with the Standard penetration test blow count sample data under stress condition, determines if to meet normal distribution, until
It is assumed that it is critical on be covered under efficacy, to normalization Standard penetration test blow count sample data inspection result do not meet normal distribution and
It is assumed that it is critical on be covered with until efficacy reaches 800kPa or more, determine therefrom that and meet normal distribution and be unsatisfactory for normal distribution
Separation be to be covered with efficacy on standard penetration test (SPT) is actually critical, and then it is actually critical according to determining standard penetration test (SPT)
On be covered with efficacy, to buried saturated sand carry out seismic liquefaction evaluation.
Further, in the step 1, buried saturated sand soil layer will be tested using conventional drilling tool and drilled to test soil layer
At the above 15cm of absolute altitude, surflaes in cleaning hole, and retaining wall is carried out as needed；
Before injection, standard penetration test (SPT) device is connected, tool joint is tightened, penetrator is put into hole to bottom hole, and
Impact opening bottom is avoided, measurement obtains drilling depth, pays attention to keeping the verticality after penetrator, drilling rod, guide rod connection；
When injection, hammered into shape using the punching of 63.5kg, with 76cm freely fall away from, using automatic drop hammer method, by penetrator with
15~30 impacts per minute are buried after middle 15cm, then start recording often squeezes into the blow counts of 10cm, obtains the hammer of accumulative 30cm
Hit number-Standard penetration test blow count N '.
Further, σ ' in the step 3aValue takes 200~300kPa.
In addition, Δ σ value takes 5~10kPa in the step 3.
It is further preferred that the normal distribution-test carries out normal distribution-test using moments method.
Beneficial effects of the present invention:
Compared with prior art, the present invention provides a kind of method for differentiating buried saturated sand earthquake liquefaction, Neng Gouke
The defect that existing specification Plays blow number liquefaction Judgment Method is not suitable for 20m or less soil layer is taken, it can be by existing standard
Blow number liquefaction Judgment Method, which is expanded, is applied to buried saturated sand seismic liquefaction evaluation, can overcome original shallow-layer sand earthquake
Liquefaction Judgment Method may not apply to the limitation of buried saturated sand, when to build earth and rockfill dam on the deep covering layer of high seismic intensity area
Alluvial deposit foundation Seismic stability evaluation and the evaluation of dam body-groundsill system quake-resistant safety provide critical support.
Detailed description of the invention
Fig. 1 is the actual measurement standard being covered under efficacy in buried saturation layer of sand difference involved in the specific embodiment of the invention
Blow number；
Fig. 2 is the coefficient of skewness and peak being covered under efficacy on difference empirical threshold involved in the specific embodiment of the invention
Spend the relation schematic diagram of coefficient；
Fig. 3 be the specific embodiment of the invention in determine it is critical on be covered with the Standard piercing that efficacy is corrected to after 100kPa
Hit number；
Fig. 4 is the buried saturated sand maximum liquefaction depth that the specific embodiment of the invention measures.
Specific embodiment
For realize the present invention technological means, character of innovation, reach purpose and effect is easy to understand, below to
The specific embodiment of invention is described in further detail.Since standard penetration test (SPT) is maturation method in the prior art, so
Its specific test process is not repeated them here.
Major technique thinking of the invention is: according under identical stress condition, the geotechnical testament parameter of same soil layer is accorded with
Close normal distribution principle, it is assumed that standard penetration test (SPT) it is critical on be covered with efficacy, effect will be covered on standard penetration test (SPT) point
Stress is less than the Standard penetration test blow count being covered at efficacy on critical and normalizes to identical stress condition (100kPa), and then adopts
It determines whether normalization Standard penetration test blow count sample data meets normal distribution with hypothesis testing, determines therefrom that layer of sand is actually critical
On be covered with efficacy, and then further to buried saturated sand carry out seismic liquefaction evaluation.Concrete mode is as follows:
Step 1: at the scene, according to specification, preferably " earthwork test rule " is to the buried sandy soils of big thickness for being more than 20m
Standard penetration test (SPT) is carried out at different parts, different depth, obtains that different location, the Standard piercing of layer of sand is hit at different depth
Number N ' in this step, will test buried saturated sand soil layer using conventional drilling tool and drill to the test above 15cm of soil layer absolute altitude, clearly
Except surflaes in hole, and retaining wall is carried out as needed；
Before injection, standard penetration test (SPT) device is connected, tool joint is tightened, penetrator is put into hole to bottom hole, and
Impact opening bottom is avoided, measurement obtains drilling depth, pays attention to keeping the verticality after penetrator, drilling rod, guide rod connection；
When injection, hammered into shape using the punching of 63.5kg, with 76cm freely fall away from, using automatic drop hammer method, by penetrator with
15~30 impacts per minute are buried after middle 15cm, then start recording often squeezes into the blow counts of 10cm, obtains the hammer of accumulative 30cm
Hit number-Standard penetration test blow count N '.
Step 2: calculating standard penetration test (SPT) under certain seismic acceleration according to standard penetration test (SPT) point stress condition and surveying
Seismic earthquake cyclic shear stress ratio CSR at pilot:
In formula: τav- seismic dynamic shear stress；amaxSurface ground motion acceleration peak；G- gravity accelerates
Degree；σv0Vertical total stress；σ'v0Above it is covered with efficacy；γd- stress Stiffness degradation coefficient.
Step 3: determining that covering layer soil body standard penetration test (SPT) is covered with efficacy σ ' on actually criticalcr, specific steps are such as
Under:
A, assume covering layer soil body standard penetration test (SPT) it is critical on be covered with efficacy be σ 'a, σ 'aTake 200~300kPa；
B, efficacy σ ' will be covered on each standard penetration test (SPT) pointv0With hypothesis it is critical on be covered with efficacy σ 'aCompared
Compared with if σ 'v0≤σ'a, then depth corresponding actual measurement Standard penetration test blow count N ' in testing site is corrected to formula (6) and is covered with effect
Under the conditions of stress is the standard stress of 100kPa, normalization Standard penetration test blow count is (N1)60；
Wherein, Pa is normal atmospheric pressure.
C, normal distribution is carried out to the Standard penetration test blow count sample data being corrected under 100kPa using hypothesis testing method
It examines (being hereafter illustrated by taking moments method (i.e. U method of inspection) as an example), judges to be covered with efficacy σ ' on empirical thresholdaLower normalization mark
Whether quasi- blow number sample data meets normal distribution, if inspection result meets normal distribution (the i.e. coefficient of skewness and kurtosis system
Number U is all satisfied U < U0.05=1.96), then illustrate to be covered with efficacy σ ' in the hypothesisaIt, can be after within the scope of application of formula (6)
It is continuous increase assume it is critical on be covered with efficacy, continue following steps.
D, increase assume it is critical on be covered with efficacy to σ 'a+ Δ σ, Δ σ can use 5~10kPa, B to C repeated, to correction
Standard penetration test blow count sample data under to 100kPa carries out normal distribution-test, until it is assumed that it is critical on be covered with efficacy
Under, to normalization Standard penetration test blow count sample data inspection result do not meet normal distribution and assume it is critical on be covered with efficacy
Until reaching 800kPa or more.
E, it is covered under efficacy according on above-mentioned each empirical threshold, to the Standard penetration test blow count sample being corrected under 100kPa
Data progress hypothesis testing is covered with efficacy σ ' on the coefficient of skewness, coefficient of kurtosis and empirical threshold as a result, drawingaRelationship it is bent
Line can meet U < U both in figure simultaneously0.05=1.96 (i.e. p>0.05) cannot meet U<U to the two simultaneously0.05=1.96 point
It is to be covered with efficacy σ ' on reality is critical that efficacy is covered on the corresponding empirical threshold of boundary's pointcr。
According under identical stress condition in this step, the geotechnical testament parameter of same soil layer meets the original of normal distribution
Reason, to being covered with the Standard penetration test blow count sample number being normalized under the identical stress condition of 100kPa under the conditions of efficacy on empirical threshold
According to carry out hypothesis testing, determine if to meet normal distribution, until it is assumed that it is critical on be covered with efficacy under, to normalization
Standard penetration test blow count sample data inspection result do not meet normal distribution and assume it is critical on be covered with efficacy and reach 800kPa
Until above, determine therefrom that meet normal distribution with the separation for being unsatisfactory for normal distribution and be standard penetration test (SPT) it is actually critical on
Be covered with efficacy, so according to determining standard penetration test (SPT) it is actually critical on be covered with efficacy, buried saturated sand is carried out
Seismic liquefaction evaluation.
Step 4: using formula (7) by buried saturation layer of sand different location, the school Standard penetration test blow count N ' at different depth
It just arrives under the conditions of the standard stress of 100kPa, the normalization standard of standard penetration test (SPT) point at acquisition different location, different depth
Blow number (N1)60:
Step 5: using the normalization standard of standard penetration test (SPT) point at the determining different location of step 4, different depth
Blow number (N1)60, according to standard penetration test (SPT) point pair at the buried saturated sand different location of formula (8) calculating, different depth
The Shear stress ratio of liquefaction CRR answered7.5:
Step 6: by Shear stress ratio of liquefaction CRR7.5Be compared with earthquake cyclic shear stress ratio CSR, when CSR >=
CRR7.5, the soil body liquefies；As CSR < CRR7.5, the soil body do not liquefy.
Below by taking the power station Mei Le dam foundation covering and deep-burying is saturated layer of sand seismic liquefaction evaluation as an example, to illustrate this hair
The implementation process of bright method.
(1) standard penetration test (SPT) is carried out to buried saturation layer of sand, measures different location, different depth (is not covered with effect ibid
Stress) at standard penetration test (SPT) point Standard penetration test blow count, test result is as shown in Figure 1.
(2) according to the stress condition of standard penetration test (SPT) point, each standard penetration test (SPT) point is calculated according to formula (5) and is being set
Caused seismic cyclic shear stress ratio CSR under acceleration.
(3) assume that coating standard penetration test (SPT) is covered with efficacy σ ' on criticalaFor 300kPa, will be less than in Fig. 1
Actual measurement Standard penetration test blow count N ' at the standard penetration test (SPT) point of 300kPa is corrected on 100kPa according to formula (6) is covered with effect
Under the conditions of power, using moments method (i.e. U method of inspection) to normalization Standard penetration test blow count (N1)60Normal distribution-test is carried out, is calculated inclined
It spends coefficient and coefficient of kurtosis is respectively 0.74 and 0.8, the coefficient of skewness and coefficient of kurtosis U are all satisfied U < U0.05=1.96 (i.e. p >
0.05) sample data after, illustrating correction meets normal distribution.
(4) increase assume it is critical on be covered with efficacy be (σ 'a+ Δ σ), Δ σ takes 10kPa, repeats (3), to being corrected to
Standard penetration test blow count sample data under 100kPa carries out normal distribution-test, calculates the corresponding coefficient of skewness and coefficient of kurtosis,
And examine whether the coefficient of skewness and coefficient of kurtosis U are all satisfied U < U0.05=1.96 (i.e. p > 0.05), until it is assumed that it is critical on
It is covered under efficacy, normalization Standard penetration test blow count sample data inspection result is not met and is covered on normal distribution and empirical threshold
Effective stress reaches 800kPa or more (this example is up to 840kPa), the coefficient of skewness being covered under efficacy on different empirical thresholds
It is shown in Table 1 with coefficient of kurtosis.
The corresponding coefficient of skewness of efficacy and coefficient of kurtosis are covered on the different empirical thresholds of table 1
(5) coefficient of skewness and coefficient of kurtosis are drawn with the relation curve for being covered with efficacy variation on empirical threshold, such as Fig. 2 institute
Show, meeting normal distribution according to Fig. 2 determination, (coefficient of skewness and coefficient of kurtosis U are all satisfied U < U0.05=1.96) and it is unsatisfactory for normal state
(coefficient of skewness and coefficient of kurtosis U cannot be all satisfied U < U for distribution0.05=1.96) boundary of efficacy is covered on empirical threshold
Point, the separation be it is practical it is critical on be covered with efficacy, as shown in Figure 2 it is practical it is critical on be covered with efficacy σ 'crFor 416kPa.
(6) using it is determining it is critical on be covered with efficacy σ 'cr=416kPa, according to formula (7) by buried saturation layer of sand not
Actual measurement Standard penetration test blow count at same position, different depth be corrected to 100kPa on be covered with (N under the conditions of efficacy1)60, return
One changes Standard penetration test blow count as shown in Figure 3.
(7) according to determining (N1)60, using standard at the buried saturated sand different location of formula (8) calculating, different depth
The corresponding Shear stress ratio of liquefaction CRR of penetration test point7.5。
(8) the earthquake shear stress ratio CSR that (5) and (8) are calculated and Shear stress ratio of liquefaction CRR7.5Compared
Compared with if CSR >=CRR7.5, then the soil body liquefies；If CSR < CRR7.5, the soil body do not liquefy.Fig. 4 gives using this hair
The buried saturation layer of sand maximum liquefaction depth of the reality that bright method differentiates.
The foregoing is merely better embodiments of the invention, are not intended to limit the invention, all in spirit of the invention
Within principle, any modification, equivalent replacement, improvement and so on be should all be included in the protection scope of the present invention.
Claims (6)
1. a kind of method for differentiating buried saturated sand earthquake liquefaction, the buried saturated sand earthquake liquefaction for being more than 20m is sentenced
Not, which comprises the following steps:
Step 1: at the scene, according to specification to be more than 20m the buried sandy soils of big thickness at different parts, different depth into
Row standard penetration test (SPT), obtain different location, at different depth layer of sand Standard penetration test blow count N '；
Step 2: calculating standard penetration test (SPT) test point under certain seismic acceleration according to standard penetration test (SPT) point stress condition
Locate seismic earthquake cyclic shear stress ratio CSR:
In formula: τav- seismic dynamic shear stress；amaxSurface ground motion acceleration peak；G- acceleration of gravity；
σv0Vertical total stress；σ'v0Above it is covered with efficacy；γd- stress Stiffness degradation coefficient；
Step 3: determining that covering layer soil body standard penetration test (SPT) is covered with efficacy σ ' on actually criticalcr, the specific steps are as follows:
A, assume covering layer soil body standard penetration test (SPT) it is critical on be covered with efficacy be σ 'a；
B, efficacy σ ' will be covered on each standard penetration test (SPT) pointv0With hypothesis it is critical on be covered with efficacy σ 'aIt is compared, if
σ'v0≤σ'a, then depth corresponding actual measurement Standard penetration test blow count N ' in testing site is corrected to formula (2) and is covered with efficacy
Under the conditions of the standard stress of 100kPa, normalization Standard penetration test blow count is (N1)60；
Wherein, PaFor normal atmospheric pressure；
C, normal distribution-test is carried out to the Standard penetration test blow count sample data being corrected under 100kPa using hypothesis testing method,
Judge to be covered with efficacy σ ' on empirical thresholdaWhether lower normalization Standard penetration test blow count sample data meets normal distribution, if inspection
It tests result and meets normal distribution, then illustrate to be covered with efficacy σ ' in the hypothesisaWithin the scope of application of formula (2), it can continue
Increase assume it is critical on be covered with efficacy, continue following steps；
D, increase assume it is critical on be covered with efficacy to σ 'a+ Δ σ, repeats B to C, to the Standard piercing being corrected under 100kPa
Hit numerical example data carry out normal distribution-test, until it is assumed that it is critical on be covered with efficacy under, to normalization Standard piercing
Hit numerical example data detection result do not meet normal distribution and assume it is critical on be covered with until efficacy reaches 800kPa or more；
E, it is covered under efficacy according on above-mentioned each empirical threshold, to the Standard penetration test blow count sample data being corrected under 100kPa
Carry out hypothesis testing is covered with efficacy σ ' on the coefficient of skewness, coefficient of kurtosis and empirical threshold as a result, drawingaRelation curve,
U < U can be met simultaneously both in figure0.05=1.96 cannot meet U < U to the two simultaneously0.05The corresponding hypothesis of=1.96 separation
It is to be covered with efficacy σ ' on reality is critical that efficacy is covered on criticalcr；
Step 4: the Standard penetration test blow count N ' at buried saturation layer of sand different location, different depth is corrected to using formula (3)
Under the conditions of the standard stress of 100kPa, the normalization Standard piercing of standard penetration test (SPT) point at acquisition different location, different depth
Hit number (N1)60:
Step 5: using the normalization Standard piercing of standard penetration test (SPT) point at the determining different location of step 4, different depth
Hit number (N1)60, corresponding according to standard penetration test (SPT) point at the buried saturated sand different location of formula (4) calculating, different depth
Shear stress ratio of liquefaction CRR7.5:
Step 6: by Shear stress ratio of liquefaction CRR7.5It is compared with earthquake cyclic shear stress ratio CSR, as CSR >=CRR7.5, soil
Body liquefies；As CSR < CRR7.5, the soil body do not liquefy.
2. a kind of method for differentiating buried saturated sand earthquake liquefaction according to claim 1, it is characterised in that: the step
It hits in rapid three to being covered with the Standard piercing being normalized under the identical stress condition of 100kPa under the conditions of efficacy on the empirical threshold
Numerical example data carry out hypothesis testing, determine if to meet normal distribution, until it is assumed that it is critical on be covered with efficacy under,
Normal distribution do not met to normalization Standard penetration test blow count sample data inspection result, and assume it is critical on be covered with efficacy and reach
Until 800kPa or more, determine therefrom that meeting normal distribution with the separation for being unsatisfactory for normal distribution is that standard penetration test (SPT) is real
Be covered with efficacy on border is critical, so according to determining standard penetration test (SPT) it is actually critical on be covered with efficacy, to buried saturation
Sand carries out seismic liquefaction evaluation.
3. a kind of method for differentiating buried saturated sand earthquake liquefaction according to claim 1, it is characterised in that:
In the step 1, buried saturated sand soil layer will be tested using conventional drilling tool and drilled to the test above 15cm of soil layer absolute altitude
Locate, surflaes in cleaning hole, and carries out retaining wall as needed；
Before injection, standard penetration test (SPT) device is connected, tool joint is tightened, penetrator is put into hole to bottom hole, and is avoided
Impact opening bottom, measurement obtain drilling depth, the verticality after keeping penetrator, drilling rod, guide rod connection；
When injection, hammered into shape using the punching of 63.5kg, with freely falling away from using automatic drop hammer method, by penetrator with every point for 76cm
Clock 15~30 times impacts are buried after middle 15cm, then start recording often squeezes into the blow counts of 10cm, obtain the hammering of accumulative 30cm
Number-Standard penetration test blow count N '.
4. a kind of method for differentiating buried saturated sand earthquake liquefaction according to claim 1, it is characterised in that: the step
σ ' in rapid threeaValue takes 200~300kPa.
5. a kind of method for differentiating buried saturated sand earthquake liquefaction according to claim 1, it is characterised in that: the step
Δ σ value takes 5~10kPa in rapid three.
6. a kind of method for differentiating buried saturated sand earthquake liquefaction, feature described in any one according to claim 1~5
Be: the normal distribution-test carries out normal distribution-test using moments method.
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| CN111705774B (en) * | 2020-05-14 | 2021-08-31 | 西南交通建设集团股份有限公司 | Saturated sandy soil liquefaction detection method based on standard penetration test |
| CN111914419B (en) * | 2020-07-31 | 2022-10-04 | 天津泰勘工程技术咨询有限公司 | Saturated silt standard penetration liquefaction judgment method |
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| CN114154332A (en) * | 2021-12-06 | 2022-03-08 | 西南石油大学 | Gravel soil earthquake liquefaction evaluation method |
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