CN106408211A - Deep saturated sand earthquake-induced liquefaction judgment method - Google Patents

Abstract

The invention provides a deep saturated sand earthquake-induced liquefaction judgment method, which comprises six steps: 1) determining standard penetration numbers of a deep saturated sand layer at different positions and in different depths; 2) determining seismic cyclic shear stress ratio CSR of different standard penetration test points of the deep saturated sand layer; 3) determining actual critical overlying effective stress of standard penetration test through a hypothetical test method; 4) obtaining normalized standard penetration numbers of the different standard penetration test points at different positions and in different depths; 5) determining liquefaction-resistance cyclic shear stress ratio CRR7.5; and 6) making a comparison between the seismic cyclic shear stress ratio CSR and the liquefaction-resistance cyclic shear stress ratio CRR7.5, and carrying out earthquake-induced liquefaction judgment. The method can overcome the defect that a standard penetration number liquefaction judgment method in the current specifications cannot be applied to the soil layer, the depth of which is larger than 20m, and can enable the existing standard penetration number liquefaction judgment method to be expanded and applied to deep saturated sand earthquake-induced liquefaction judgment.

Description

A kind of method differentiating buried saturated sand earthquake liquefaction

Technical field

The invention belongs to geotechnological quake-resistant safety evaluates field, it is related to a kind of method differentiating buried saturated sand earthquake liquefaction.

Background technology

China's hydroelectric resources more than 80% is distributed in the west area that seismic activity is frequent and intensity is big, and this area riverbed is big Have deep covering layer more, in deep covering layer, be commonly present soil layer or the lenticular body that sand etc. may liquefy under geological process. With the enforcement of strategy to develop western regions, increasing earth-rock works will be built on deep covering layer, in deep covering layer Sand or its lenticular body stability under geological process is the key issue being related to engineering safety and feasibility, but buried saturation Sand Liquefaction differentiate be at present academicly with engineering on difficulties.Standard penetration test (SPT) is that widely used scene is former Bit test method, is applied quite varied in engineering based on the method that standard penetration test (SPT) differentiates foundation soil liquefaction probability, but Standard penetration test (SPT) liquefaction Judgment Method in existing specification, (overlying effective stress is substantially in 20m for the foundation soil depth that it is suitable for Upper is 200kPa) within, the buried saturated sand foundation liquefaction more than 20m (overlying effective stress substantially 200kPa) is sentenced Not, existing method is inapplicable.

Content of the invention

A kind of purpose of the method differentiating buried saturated sand earthquake liquefaction of the present invention is by based on standard penetration test (SPT) Shallow soil seismic liquefaction evaluation method expansive approach is in buried saturated sand seismic liquefaction evaluation；Prior art is only applicable to shallow-layer Sand Liquefaction differentiates, be applied to the liquefaction of soil mass more than 20m for the overlying effective stress differentiate actually lack enough according to According to.

For achieving the above object, the present invention provides technical scheme below：

A kind of method differentiating buried saturated sand earthquake liquefaction, for the buried saturated sand foundation liquefaction more than 20m Differentiate it is characterised in that comprising the following steps：

Step one, at the scene, according to specification, to big thickness, buried sandy soils carry out standard at different parts, different depth Penetration test, obtain diverse location, at different depth layer of sand Standard penetration test blow count N '；

Step 2, according to standard penetration test (SPT) point stress condition, calculate standard penetration test (SPT) under certain seismic acceleration and survey Seismic earthquake cyclic shear stress ratio CSR at pilot：

In formula：τ_avSeismic dynamic shear stress；a_max- surface ground motion acceleration peak；G- gravity accelerates Degree；σ_v0- vertical total stress；σ'_v0- overlying effective stress；r_dStress Stiffness degradation coefficient；

Step 3, actual critical overlying effective stress σ of determination covering layer soil body standard penetration test (SPT) '_cr, concrete steps are such as Under：

The critical overlying effective stress that A, supposition cover layer soil body standard penetration test (SPT) is σ '_a；

B, by each standard penetration test (SPT) point overlying effective stress σ '_v0With suppose critical overlying effective stress σ '_aCompared Relatively, if σ '_v0≤σ'_a, then with formula (2), corresponding for testing site depth actual measurement Standard penetration test blow count N ' is corrected to overlying effective Under the conditions of stress is the standard stress of 100kPa, the Standard penetration test blow count after correction is (N₁)₆₀；

Wherein, P_aFor 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 Inspection, judge empirical threshold overlying effective stress σ '_aWhether the Standard penetration test blow count sample data after lower correction meets normal state is divided Cloth, if assay meets normal distribution, illustrate this supposition overlying effective stress σ '_aWithin the scope of application of formula (2), Can continue to increase the critical overlying effective stress supposing, continue following steps；

D, increase the critical overlying effective stress supposing to σ '_a+ Δ σ, repeats B to C, to the standard being corrected under 100kPa Blow number sample data carries out normal distribution-test, until under the critical overlying effective stress supposing, to the mark after correction Quasi- blow number sample data assay do not meet normal distribution and suppose critical overlying effective stress reach 800kPa with Till upper；

E, according under above-mentioned each empirical threshold overlying effective stress, to the Standard penetration test blow count sample being corrected under 100kPa Data carries out the result of hypothesis testing, draw the coefficient of skewness, coefficient of kurtosis and empirical threshold overlying effective stress σ '_aRelation bent Line, both in figures can meet U simultaneously<U_0.05=1.96 can not meet U to both simultaneously<U_0.05=1.96 separation is corresponding Empirical threshold overlying effective stress as actual critical overlying effective stress σ '_cr；

Step 4, using formula (3) by the Standard penetration test blow count N ' school at buried saturation layer of sand diverse location, different depth Under the conditions of just arriving the standard stress of 100kPa, the normalization standard of standard penetration test (SPT) point at acquisition diverse location, different depth Blow number (N₁)₆₀：

The normalization standard of standard penetration test (SPT) point at step 5, the diverse location being determined using step 4, different depth Blow number (N₁)₆₀, according to standard penetration test (SPT) point pair at formula (4) the buried saturated sand diverse location of calculating, different depth The Shear stress ratio of liquefaction CRR answering_7.5：

Step 6, by Shear stress ratio of liquefaction CRR_7.5Be compared with earthquake cyclic shear stress ratio CSR, when CSR >= CRR_7.5, the soil body liquefies；As CSR ＜ CRR_7.5, the soil body do not liquefy.

It is further preferred that described step 3 is normalized to 100kPa phase under the conditions of described empirical threshold overlying effective stress Carry out hypothesis testing with the Standard penetration test blow count sample data under stress condition, determine if to meet normal distribution, until It is assumed that critical overlying effective stress under, to correction after Standard penetration test blow count sample data assay do not meet normal distribution And till the critical overlying effective stress supposing reaches more than 800kPa, determine therefrom that meeting normal distribution divides with being unsatisfactory for normal state The separation of cloth is the actual critical overlying effective stress of standard penetration test (SPT), and then faces according to the standard penetration test (SPT) determining is actual Boundary's overlying effective stress, carries out seismic liquefaction evaluation to buried saturated sand.

Further, in described step one, buried saturated sand soil layer will be tested using conventional drilling tool and hole to test soil layer At the above 15cm of absolute altitude, remove in the hole surflaes, and carry out retaining wall as needed；

Before injection, connect standard penetration test (SPT) device, tighten tool joint, penetrator is put in the hole to bottom hole, and Avoid impact opening bottom, measurement obtains drilling depth, note the perpendicularity after keeping penetrator, drilling rod, guide post to couple；

During injection, using the punching hammer 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 several Standard penetration test blow count N '.

Further, σ ' in described step 3_aValue takes 200～300kPa.

Additionally, Δ σ value takes 5～10kPa in described step 3.

It is further preferred that described normal distribution-test carries out normal distribution-test using moments method.

Beneficial effects of the present invention：

Compared with prior art, the invention provides a kind of differentiate buried saturated sand earthquake liquefaction method, Neng Gouke Take the defect that existing specification Plays blow number liquefaction Judgment Method is not suitable for below 20m soil layer, can be by existing standard Blow number liquefaction Judgment Method expansive approach, in 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 being to build earth and rockfill dam on the deep covering layer of high seismic intensity area Alluvial deposit foundation Seismic stability evaluation and dam body-groundsill system quake-resistant safety evaluation provide critical support.

Brief description

Fig. 1 is the actual measurement standard under the buried saturation layer of sand difference overlying effective stress involved by the specific embodiment of the invention Blow number；

Fig. 2 is the coefficient of skewness and peak under the different empirical threshold overlying effective stresses involved by the specific embodiment of the invention The relation schematic diagram of degree coefficient；

Fig. 3 is that the critical overlying effective stress determining in the specific embodiment of the invention is corrected to the Standard piercing after 100kPa Hit number；

Fig. 4 is the buried saturated sand maximum liquefaction depth that the specific embodiment of the invention records.

Specific embodiment

Technological means, character of innovation, reached purpose and effect for making the present invention realize are easy to understand, below to this The specific embodiment of invention describes in further detail.Because standard penetration test (SPT) is maturation method of the prior art, so Its concrete process of the test is not repeated.

The major technique thinking of the present invention is：According under identical stress condition, the geotechnical testament parameter of same soil layer accords with The principle closing normal distribution, will be effective for standard penetration test (SPT) point overlying it is assumed that the critical overlying effective stress of standard penetration test (SPT) The Standard penetration test blow count that stress is less than at critical overlying effective stress normalizes to identical stress condition (100kPa), and then adopts Determine whether the Standard penetration test blow count sample data after correction meets normal distribution with hypothesis testing, determine therefrom that layer of sand is actual and face Boundary's overlying effective stress, and then further seismic liquefaction evaluation is carried out to buried saturated sand.Concrete mode is as follows：

Step one, at the scene, according to specification, preferably《Earthwork test rule》To big thickness, buried sandy soils are in different portions Position, carry out standard penetration test (SPT) at different depth, obtain diverse location, at different depth layer of sand Standard penetration test blow count N ', this In step, buried saturated sand soil layer will be tested using conventional drilling tool and hole to the test above 15cm of soil layer absolute altitude, remove in the hole Surflaes, and carry out retaining wall as needed；

Before injection, connect standard penetration test (SPT) device, tighten tool joint, penetrator is put in the hole to bottom hole, and Avoid impact opening bottom, measurement obtains drilling depth, note the perpendicularity after keeping penetrator, drilling rod, guide post to couple；

During injection, using the punching hammer 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 several Standard penetration test blow count N '.Step 2, according to standard penetration test (SPT) point stress condition, calculate certain seismic acceleration subscript Seismic earthquake cyclic shear stress ratio CSR at quasi- penetration test test point：

In formula：τ_avSeismic dynamic shear stress；a_max- surface ground motion acceleration peak；G- gravity accelerates Degree；σ_v0- vertical total stress；σ'_v0- overlying effective stress；r_dStress Stiffness degradation coefficient.

Step 3, actual critical overlying effective stress σ of determination covering layer soil body standard penetration test (SPT) '_cr, concrete steps are such as Under：

The critical overlying effective stress that A, supposition cover layer soil body standard penetration test (SPT) is σ '_a, σ '_aTake 200～300kPa；

B, by each standard penetration test (SPT) point overlying effective stress σ '_v0With suppose critical overlying effective stress σ '_aCompared Relatively, if σ '_v0≤σ'_a, then with formula (6), corresponding for testing site depth actual measurement Standard penetration test blow count N ' is corrected to overlying effective Under the conditions of stress is the standard stress of 100kPa, the Standard penetration test blow count after correction is (N₁)₆₀；

Wherein, Pa is 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 Inspection (hereafter taking moments method (i.e. U method of inspection) as a example illustrating), judge empirical threshold overlying effective stress σ '_aAfter lower correction Whether Standard penetration test blow count sample data meets normal distribution, if assay meets normal distribution (the i.e. coefficient of skewness and kurtosis Coefficient U is satisfied by U<U_0.05=1.96), then illustrate this supposition overlying effective stress σ '_aWithin the scope of application of formula (6), can Continue to increase the critical overlying effective stress supposing, continue following steps.

D, increase the critical overlying effective stress supposing to σ '_a+ Δ σ, Δ σ can use 5～10kPa, repeat B to C, to correction Standard penetration test blow count sample data under 100kPa carries out normal distribution-test, until in the critical overlying effective stress supposing Under, the critical overlying that the Standard penetration test blow count sample data assay after correction is not met normal distribution and supposes has effect Till power reaches more than 800kPa.

E, according under above-mentioned each empirical threshold overlying effective stress, to the Standard penetration test blow count sample being corrected under 100kPa Data carries out the result of hypothesis testing, draw the coefficient of skewness, coefficient of kurtosis and empirical threshold overlying effective stress σ '_aRelation bent Line, both in figures can meet U simultaneously<U_0.05=1.96 (i.e. p>0.05) U can not be met to both simultaneously<U_0.05=1.96 point Boundary's point corresponding empirical threshold overlying effective stress as actual critical overlying effective stress σ '_cr.

According under identical stress condition in this step, the geotechnical testament parameter of same soil layer meets the former of normal distribution Reason, to the Standard penetration test blow count sample number being normalized under the conditions of empirical threshold overlying effective stress under the identical stress condition of 100kPa According to carrying out hypothesis testing, determine if to meet normal distribution, until under the critical overlying effective stress supposing, after correction Standard penetration test blow count sample data assay do not meet normal distribution and suppose critical overlying effective stress reach Till more than 800kPa, determine therefrom that meeting normal distribution with the separation being unsatisfactory for normal distribution is that standard penetration test (SPT) is actual Critical overlying effective stress, and then according to the actual critical overlying effective stress of the standard penetration test (SPT) determining, to buried saturated sand Soil carries out seismic liquefaction evaluation.

Step 4, using formula (7) by the Standard penetration test blow count N ' school at buried saturation layer of sand diverse location, different depth Under the conditions of just arriving the standard stress of 100kPa, the normalization standard of standard penetration test (SPT) point at acquisition diverse location, different depth Blow number (N₁)₆₀：

The normalization standard of standard penetration test (SPT) point at step 5, the diverse location being determined using step 4, different depth Blow number (N₁)₆₀, according to standard penetration test (SPT) point pair at formula (8) the buried saturated sand diverse location of calculating, different depth The Shear stress ratio of liquefaction CRR answering_7.5：

Step 6, by Shear stress ratio of liquefaction CRR_7.5Be compared with earthquake cyclic shear stress ratio CSR, when CSR >= CRR_7.5, the soil body liquefies；As CSR ＜ CRR_7.5, the soil body do not liquefy.

Below, to illustrate this taking Mei Le power station dam foundation covering and deep-burying saturation layer of sand seismic liquefaction evaluation as a example The implementation process of bright method.

(1) standard penetration test (SPT) is carried out to buried saturation layer of sand, record diverse location, (different overlyings are effective for different depth Stress) place's standard penetration test (SPT) point Standard penetration test blow count, test result is as shown in Figure 1.

(2) stress condition according to standard penetration test (SPT) point, calculates each standard penetration test (SPT) point according to formula (5) and is setting The seismic cyclic shear stress ratio CSR causing under acceleration.

(3) suppose cover layer standard penetration test (SPT) critical overlying effective stress σ '_aFor 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 to 100kPa overlying according to formula (6) effect Under the conditions of power, using moments method (i.e. U method of inspection) to the Standard penetration test blow count (N after correction₁)₆₀Carry out normal distribution-test, calculate The coefficient of skewness and coefficient of kurtosis are respectively 0.74 and 0.8, and the coefficient of skewness and coefficient of kurtosis U are satisfied by U<U_0.05=1.96 (i.e. p> 0.05) sample data after, illustrating to correct meets normal distribution.

(4) increasing the critical overlying effective stress supposing is (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 check whether the coefficient of skewness and coefficient of kurtosis U are satisfied by U<U_0.05=1.96 (i.e. p>0.05), until suppose critical on It is covered with efficacy, the Standard penetration test blow count sample data assay after correction is not met on normal distribution and empirical threshold It is covered with efficacy and reach more than 800kPa (this example is up to 840kPa), the degree of bias system under different empirical threshold overlying effective stresses Number and coefficient of kurtosis are shown in Table 1.

The different corresponding coefficient of skewness of empirical threshold overlying effective stress of table 1 and coefficient of kurtosis

(5) draw the relation curve that the coefficient of skewness and coefficient of kurtosis change with empirical threshold overlying effective stress, as Fig. 2 institute Show, (coefficient of skewness and coefficient of kurtosis U are satisfied by U to meet normal distribution according to Fig. 2 determination<U_0.05=1.96) and be unsatisfactory for normal state (coefficient of skewness and coefficient of kurtosis U can not be satisfied by U for distribution<U_0.05=1.96) boundary of empirical threshold overlying effective stress Point, this separation be actual critical overlying effective stress, as shown in Figure 2 actual critical overlying effective stress σ '_crFor 416kPa.

(6) using determine critical overlying effective stress 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 is corrected to the (N under the conditions of the overlying effective stress of 100kPa₁)₆₀, school Standard penetration test blow count after just is as shown in Figure 3.

(7) according to (N determining₁)₆₀, using standard at formula (8) the buried saturated sand diverse location of calculating, different depth Penetration test point corresponding Shear stress ratio of liquefaction CRR_7.5.

(8) by (5) and (8) calculated earthquake shear stress ratio CSR and Shear stress ratio of liquefaction CRR_7.5Compared Relatively, if CSR >=CRR_7.5, then the soil body liquefy；If CSR is ＜ CRR_7.5, the soil body do not liquefy.Fig. 4 gives using this The reality buried saturation layer of sand maximum liquefaction depth that bright method differentiation obtains.

The foregoing is only the better embodiment of the present invention, not in order to limit the present invention, all spirit in the present invention Within principle, any modification, equivalent substitution and improvement made etc., should be included within the scope of the present invention.

Claims (6)

1. a kind of method differentiating buried saturated sand earthquake liquefaction, sentences for the buried saturated sand foundation liquefaction more than 20m Not it is characterised in that comprising the following steps：

Step one, at the scene, according to specification, to big thickness, buried sandy soils carry out Standard piercing at different parts, different depth Test, obtain diverse location, at different depth layer of sand Standard penetration test blow count N '；

Step 2, according to standard penetration test (SPT) point stress condition, calculate standard penetration test (SPT) test point under certain seismic acceleration Locate seismic earthquake cyclic shear stress ratio CSR：

$CSR=\frac{{\mathrm{\&tau;}}_{av}}{{\mathrm{\&sigma;}}_{v0}^{\&prime;}}=0.65(a_{\max }/g)({\mathrm{\&sigma;}}_{v0}/{\mathrm{\&sigma;}}_{v0}^{\&prime;}){\mathrm{\&gamma;}}_d---\left(1\right)$

In formula：τ_avSeismic dynamic shear stress；a_max- surface ground motion acceleration peak；G- acceleration of gravity； σ_v0- vertical total stress；σ'_v0- overlying effective stress；r_dStress Stiffness degradation coefficient；

Step 3, actual critical overlying effective stress σ of determination covering layer soil body standard penetration test (SPT) '_cr, comprise the following steps that：

The critical overlying effective stress that A, supposition cover layer soil body standard penetration test (SPT) is σ '_a；

B, by each standard penetration test (SPT) point overlying effective stress σ '_v0With the critical overlying effective stress σ ' supposing_aIt is compared, if σ'_v0≤σ′_a, then with formula (2), corresponding for testing site depth actual measurement Standard penetration test blow count N ' is corrected to overlying effective stress Under the conditions of the standard stress of 100kPa, the Standard penetration test blow count after correction is (N₁)₆₀；

${\left(N_1\right)}_{60}=N^{\&prime;}\&times;\left(\frac{p_a}{{\mathrm{\&sigma;}}_{v0}^{\&prime;}}\right)---\left(2\right)$

Wherein, P_aFor 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 empirical threshold overlying effective stress σ '_aWhether the Standard penetration test blow count sample data after lower correction meets normal distribution, if Assay meets normal distribution, then illustrate this supposition overlying effective stress σ '_aWithin the scope of application of formula (2), can continue The continuous critical overlying effective stress increasing supposition, continues following steps；

D, increase the critical overlying effective stress supposing to σ '_a+ Δ σ, repeats B to C, to the Standard piercing being corrected under 100kPa Hit numerical example data and carry out normal distribution-test, until under the critical overlying effective stress supposing, passing through to the standard after correction Enter to hit the critical overlying effective stress that numerical example data detection result do not meet normal distribution and suppose to reach more than 800kPa and be Only；

E, according under above-mentioned each empirical threshold overlying effective stress, to the Standard penetration test blow count sample data being corrected under 100kPa Carry out the result of hypothesis testing, draw the coefficient of skewness, coefficient of kurtosis and empirical threshold overlying effective stress σ '_aRelation curve, Both in figures can meet U simultaneously<U_0.05=1.96 can not meet U to both simultaneously<U_0.05=1.96 corresponding supposition of separation Critical overlying effective stress is actual critical overlying effective stress σ '_cr；

Step 4, using formula (3), the Standard penetration test blow count N ' at buried saturation layer of sand diverse location, different depth is corrected to Under the conditions of the standard stress of 100kPa, the normalization Standard piercing of standard penetration test (SPT) point at acquisition diverse location, different depth Hit number (N₁)₆₀：

$\begin{array}{cc}{\left(N_1\right)}_{60}=N^{\&prime;}\&times;\left(\frac{p_a}{{\mathrm{\&sigma;}}_{v0}^{\&prime;}}\right)& {\mathrm{\&sigma;}}_{v0}^{\&prime;}\&le;{\mathrm{\&sigma;}}_{cr}^{\&prime;}\\ {\left(N_1\right)}_{60}=N^{\&prime;}\&times;\left(\frac{p_a}{{\mathrm{\&sigma;}}_{cr}^{\&prime;}}\right)& {\mathrm{\&sigma;}}_{v0}^{\&prime;}>{\mathrm{\&sigma;}}_{cr}^{\&prime;}\end{array}---\left(3\right)$

The normalization Standard piercing of standard penetration test (SPT) point at step 5, the diverse location being determined using step 4, different depth Hit number (N₁)₆₀, corresponding according to standard penetration test (SPT) point at formula (4) the buried saturated sand diverse location of calculating, different depth Shear stress ratio of liquefaction CRR_7.5：

${\mathrm{CRR}}_{7.5}=\frac{1}{34-{\left(N_1\right)}_{60}}+\frac{{\left(N_1\right)}_{60}}{135}+\frac{50}{{\&lsqb;10\&CenterDot;{\left(N_1\right)}_{60}+45\&rsqb;}^2}-\frac{1}{200}---\left(4\right)$

Step 6, by Shear stress ratio of liquefaction CRR_7.5It is compared with earthquake cyclic shear stress ratio CSR, as CSR >=CRR_7.5, soil Body liquefies；As CSR ＜ CRR_7.5, the soil body do not liquefy.

2. according to claim 1 a kind of differentiate buried saturated sand earthquake liquefaction method it is characterised in that：Described step In rapid three, the Standard piercing being normalized under the identical stress condition of 100kPa under the conditions of described empirical threshold overlying effective stress is hit Numerical example data carries out hypothesis testing, determines if to meet normal distribution, until under the critical overlying effective stress supposing, Normal distribution, and the critical overlying effective stress supposing are not met to the Standard penetration test blow count sample data assay after correction Till reaching more than 800kPa, determine therefrom that meeting normal distribution with the separation being unsatisfactory for normal distribution is standard penetration test (SPT) Actual critical overlying effective stress, and then according to the actual critical overlying effective stress of the standard penetration test (SPT) determining, to buried full Carry out seismic liquefaction evaluation with sand.

3. according to claim 1 a kind of differentiate buried saturated sand earthquake liquefaction method it is characterised in that：Described step In rapid one, buried saturated sand soil layer will be tested using conventional drilling tool and hole to the test above 15cm of soil layer absolute altitude, remove in the hole Surflaes, and carry out retaining wall as needed；

Before injection, connect standard penetration test (SPT) device, tighten tool joint, penetrator is put in the hole to bottom hole, and avoids Impact opening bottom, measurement obtains drilling depth, the perpendicularity after keeping penetrator, drilling rod, guide post to couple；

During injection, using the punching hammer of 63.5kg, freely falling away from using automatic drop hammer method, by penetrator with every point with 76cm 15～30 impacts of clock are buried after middle 15cm, then start recording often squeezes into the blow counts of 10cm, obtains the hammering of accumulative 30cm Number Standard penetration test blow count N '.

4. according to claim 1 a kind of differentiate buried saturated sand earthquake liquefaction method it is characterised in that：Described step σ ' in rapid three_aValue takes 200～300kPa.

5. according to claim 1 a kind of differentiate buried saturated sand earthquake liquefaction method it is characterised in that：Described step In rapid three, Δ σ value takes 5～10kPa.

6. the method for a kind of differentiation buried saturated sand earthquake liquefaction according to Claims 1 to 5 any one, its feature It is：Described normal distribution-test carries out normal distribution-test using moments method.