JPH0663218B2 - Method of estimating liquefaction strength of ground during earthquake - Google Patents
Method of estimating liquefaction strength of ground during earthquakeInfo
- Publication number
- JPH0663218B2 JPH0663218B2 JP10635886A JP10635886A JPH0663218B2 JP H0663218 B2 JPH0663218 B2 JP H0663218B2 JP 10635886 A JP10635886 A JP 10635886A JP 10635886 A JP10635886 A JP 10635886A JP H0663218 B2 JPH0663218 B2 JP H0663218B2
- Authority
- JP
- Japan
- Prior art keywords
- liquefaction strength
- resistance
- liquefaction
- average
- principal stress
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は地盤の地震時液状化強度を推定する方法に関す
るものである。TECHNICAL FIELD The present invention relates to a method of estimating the liquefaction strength of a ground during an earthquake.
（従来の技術およびその問題点） 砂質地盤が地震等の外力によつて、その間隙水圧が上昇
し、有効応力が減少してせん断強度が急激に低下するこ
とにより、地下水位以下で液体状になる現象を液状化と
いう。かかる液状化が発生すると、地表あるいは地中の
構造物に有害な影響を与えるため、これを予測すること
は耐震設計上極めて重要なことである。(Prior art and its problems) The sandy ground is in a liquid state below the groundwater level because the pore water pressure rises due to an external force such as an earthquake, the effective stress decreases and the shear strength sharply decreases. This phenomenon is called liquefaction. If such liquefaction occurs, it will have a harmful effect on the surface of the ground or structures in the ground, and it is extremely important to predict this in terms of seismic design.
かかる液状化を予測する従来の主な方法としては、例え
ば、地形、地質等に基づいた概略の予測方法、Ｎ
値、粒度試験結果等を用いる簡易予測方法、室内液状
化試験及び地震応答解析等に基づいた詳細な予測方法、
原位置試験あるいは振動台を用いた試験に基づいた予
測方法等がある。As a conventional main method for predicting such liquefaction, for example, a rough prediction method based on topography, geology, etc., N
Simple prediction method using values, particle size test results, etc., detailed prediction method based on indoor liquefaction test and seismic response analysis,
There are prediction methods based on in-situ tests or tests using a vibration table.
これらの予測方法に於いて、は安価に行なえるもの
の、極めて概略的な予測しか行なえず、逆に、は精
度の高い予測を行なえるものの、コストが非常に高い。
その為、通常の耐震地盤調査ではの方法が最もよく利
用されている。この方法は、標準貫入試験から得られる
Ｎ値に基づくもので、比較的精度も高いが、ボーリング
も併せて実施しなければならないので、簡易予測方法と
はいつても、比較的時間を要し、コストも高いという問
題点がある。Among these prediction methods, can be made at a low cost, but can make only a very rough prediction, and conversely, can make a highly accurate prediction, but the cost is very high.
Therefore, the method of usual seismic ground survey is most often used. This method is based on the N value obtained from the standard penetration test and has relatively high accuracy, but since boring must also be performed, it always takes a relatively long time with the simple prediction method. However, there is a problem that the cost is high.
以上に加えて、近来、前記標準貫入試験と比較して、低
コストであると同時に、試験データが深度方向に連続的
に得られるという利点を有しているコーン貫入試験に基
づいた予測方法も幾つか提案されている。しかしながら
これらの方法はいずれも先端貫入抵抗のみ、あるいは先
端貫入抵抗と周面摩擦抵抗を用いたものであつて、基本
的にはＮ値を用いる前記の方法に準じたものであり、
間隙水圧を考慮していないため、精度は余り高くない。In addition to the above, a prediction method based on the cone penetration test, which has the advantage that the test data is continuously obtained in the depth direction at the same time as the cost is low compared to the standard penetration test, is also available. Several have been proposed. However, each of these methods uses only the tip penetration resistance, or uses the tip penetration resistance and the circumferential surface friction resistance, and basically conforms to the above method using the N value.
Since the pore water pressure is not taken into consideration, the accuracy is not so high.
本発明は三成分コーン貫入試験を行なつて、先端貫入抵
抗及び周面摩擦抵抗に加えて、間隙水圧も測定し、この
間隙水圧を考慮することにより、地盤の地震時液状化強
度の推定を精度良く、しかも低コストで行なえるように
し、以つて前述した従来の問題点を解決することを目的
とするものである。The present invention conducts a three-component cone penetration test to measure the pore water pressure in addition to the tip penetration resistance and the circumferential surface friction resistance, and by considering this pore water pressure, it is possible to estimate the liquefaction strength of the ground during an earthquake. It is an object of the present invention to make it possible to carry out with high accuracy and at low cost, thereby solving the above-mentioned conventional problems.
（問題を解決するための手段） 上述した課題を解決するために、本発明では、対象とす
る地盤に対して三成分コーン貫入試験を行なって先端貫
入抵抗、周面摩擦抵抗及び間隙水圧を測定し、有効上載
圧から求めた平均主応力から、前記間隙水圧より静水圧
を減じて成る過剰間隙水圧を減じて平均有効主応力を求
め、前記先端貫入抵抗と該平均有効主応力の比と、液状
化強度の対応関係により対象地盤の地震時液状化強度を
推定する方法を提案する。(Means for Solving the Problem) In order to solve the above-mentioned problems, in the present invention, a three-component cone penetration test is performed on the target ground to measure the tip penetration resistance, the peripheral friction resistance, and the pore water pressure. Then, from the average principal stress obtained from the effective top loading pressure, the average effective principal stress is obtained by subtracting the excess pore water pressure obtained by subtracting the hydrostatic pressure from the pore water pressure, and the ratio of the tip penetration resistance and the average effective principal stress, We propose a method to estimate the liquefaction strength of the target ground during an earthquake based on the corresponding relationship of the liquefaction strength.
また本発明では、上述した方法において対象地盤の地震
時液状化強度を推定する際、前記周面摩擦抵抗、先端貫
入抵抗とから求められる摩擦比がある値よりも大きな時
には、該摩擦比に対応する正の補正量を前記推定液状化
強度に加える方法を提案する。Further, in the present invention, when estimating the earthquake liquefaction strength of the target ground by the method described above, when the friction ratio obtained from the peripheral friction resistance and the tip penetration resistance is larger than a certain value, the friction ratio is supported. A method of adding a positive correction amount to the estimated liquefaction strength is proposed.
（作用） 先端貫入抵抗と平均応力との対応関係から液状化強度を
推定する際、平均応力として、過剰間隙水圧を考慮した
平均有効主応力を用いる方が、平均主応力を用いるもの
と比較して対応関係が強いため、より精度良く液状化強
度の推定を行うことができる。(Operation) When estimating the liquefaction strength from the correspondence between the tip penetration resistance and the average stress, it is better to use the average effective principal stress considering the excess pore water pressure as the average stress, compared to the one using the average principal stress. Since the correspondence relationship is strong, the liquefaction strength can be estimated more accurately.
細粒の地盤で摩擦比が大きい場合には、液状化強度の推
定値に正の補正量を加えることにより、液状化強度の過
小評価を防ぐことができる。When the friction ratio is large on a fine-grained ground, it is possible to prevent underestimation of the liquefaction strength by adding a positive correction amount to the estimated value of the liquefaction strength.
（実施例） 次に本発明を実施例につき図面を参照して詳細に説明す
る。(Embodiment) Next, the present invention will be described in detail with reference to the drawings regarding an embodiment.
第１図は三成分コーン貫入試験機の要部の一例を示すも
ので、１はコーンプローブ、２は地上あるいは試験車上
等に設置する油圧貫入機（図示せず）に連なるロツドで
ある。コーンプローブ１に於いて、符号３は先端の円す
い状コーンで、このコーン３は先端角６０°、外径３６
mm、水平投影面積１０cm2の形状を標準とするものであ
る。該コーン３の直上部に、水で飽和させたフイルタ４
を取り付け、コーン３の貫入に伴つて発生する間隙水圧
を前記フイルタ４を介して水圧計５により測定する。符
号６はコーン３の貫入に際して作用する地盤の抵抗力、
即ち先端貫入抵抗測定用のストレインゲージである。ま
た符号７は外径３６mm、面積100cm2の形状を標準とする
フリクシヨンスリーブであり、コーン３の貫入に際し
て、このフリクシヨンスリーブ７に作用する摩擦力、即
ち周面摩擦抵抗をストレインゲージ８によつて測定す
る。以上の構成に於いて、対象とする地盤上の所定位置
に設置した貫入機に連なるロツド２により、毎秒１cm〜
２cmの標準速度てコーン３を貫入し、この際の先端貫入
抵抗、周面摩擦抵抗及び間隙水圧を、ロツド２内のケー
ブルを介して外部で測定することができるのである。FIG. 1 shows an example of a main part of a three-component cone penetration tester, where 1 is a cone probe and 2 is a rod connected to a hydraulic penetration machine (not shown) installed on the ground or on a test vehicle. In the cone probe 1, reference numeral 3 is a conical cone having a tip, and the cone 3 has a tip angle of 60 ° and an outer diameter of 36.
The standard size is mm and the horizontal projection area is 10 cm 2 . Directly above the cone 3 is a filter 4 saturated with water.
And the pore water pressure generated with the penetration of the cone 3 is measured by the water pressure gauge 5 through the filter 4. Reference numeral 6 is the ground resistance acting when the cone 3 penetrates,
That is, it is a strain gauge for measuring the tip penetration resistance. Reference numeral 7 is a friction sleeve having an outer diameter of 36 mm and an area of 100 cm 2 as a standard. When the cone 3 penetrates, the friction force acting on the friction sleeve 7, that is, the frictional resistance on the peripheral surface is applied to the strain gauge 8. To measure. In the above structure, the rod 2 connected to the intrusor installed at a predetermined position on the target ground allows the distance from 1 cm per second
The cone 3 is penetrated at a standard speed of 2 cm, and the tip penetration resistance, the circumferential surface friction resistance and the pore water pressure at this time can be measured externally via the cable in the rod 2.
本発明はこのように対象とする地盤に対する先端貫入抵
抗、周面摩擦抵抗及び間隙水圧を測定し、そして前述し
たように有効上載圧から求めた平均主応力から過剰間隙
水圧、即ち前記間隙水圧から静水圧を減じたもの、を減
じて平均有効主応力を求め、前記先端貫入抵抗と該平均
有効主応力の比と、液状化強度の対応関係により対象地
盤の地震時液状化強度を推定するものであり、かかる
際、前記周面摩擦抵抗、先端貫入抵抗とから求められる
摩擦比がある値（例えば）0.5％よりも大きな時には、
該摩擦比に対応する正の補正量を前記推定液状化強度に
加える。即ち、本発明は次に示す関係式により、液状化
強度を推定するのである。The present invention thus measures the tip penetration resistance, the circumferential surface friction resistance and the pore water pressure for the target ground, and as described above, from the average principal stress obtained from the effective loading pressure to the excess pore water pressure, that is, from the pore water pressure. What reduces the hydrostatic pressure, and obtains the average effective principal stress by subtracting it, and estimates the liquefaction strength during earthquake of the target ground by the correspondence relationship between the tip penetration resistance and the average effective principal stress and the liquefaction strength. At this time, when the friction ratio obtained from the peripheral frictional resistance and the tip penetration resistance is larger than a certain value (for example) 0.5%,
A positive correction amount corresponding to the friction ratio is added to the estimated liquefaction strength. That is, the present invention estimates the liquefaction strength by the following relational expression.
Rl＝ｆ（qc／σｍ′）＋ΔＲ……(1) 但し、 Rl：液状化強度（繰り返し応力比） qc：先端貫入抵抗（Kgf/cm2） σｍ′：平均有効主応力（Kgf/cm2） σmo′：平均主応力（Kgf/cm2） σＶ′：有効上載圧（Kgf/cm2） ΔＵ：過剰間隙水圧（Kgf/cm2） Ud：貫入に伴う間隙水圧（Kgf/cm2） Uw：静水圧（Kgf/cm2） ΔＲ：補正量 Rf：摩擦比（Rf＝fs/qc（％）） fs：周面摩擦抵抗（Kgf/cm2） 尚、先端貫入抵抗（qc）あるいは周面摩擦抵抗（fs）
は、間隙水圧（Ud）の値に若干影響される性質を有する
ため、その影響が大きいと考えられる場合には検定を行
つた上で、測定値の補正を行なう場合もある。Rl = f (qc / σ m ′) + ΔR (1) where Rl: Liquefaction strength (repetitive stress ratio) qc: Tip penetration resistance (Kgf / cm 2 ) σ m ′: Average effective principal stress (Kgf / cm 2 ) σ mo ′: Average principal stress (Kgf / cm 2 ) σ V ′: Effective loading pressure (Kgf / cm 2 ) ΔU: Excess pore water pressure (Kgf / cm 2 ) Ud: Pore water pressure associated with penetration (Kgf / cm 2 ) Uw: Hydrostatic pressure (Kgf / cm 2 ) ΔR: Correction amount Rf: Friction ratio (Rf = fs / qc (% )) fs: skin friction resistance (Kgf / cm 2) Note that the tip penetration resistance (qc) or peripheral surface frictional resistance (fs)
Has a property that it is slightly affected by the value of pore water pressure (Ud), and if the effect is considered to be large, a measurement may be performed after performing a test.
ところで、地盤の性状を表わす尺度の一である相対密度
（Dro）は、地盤の締まり具合を主に反映するものであ
り、液状化強度と極めて密接な関係にあることが知られ
ている。そこで、豊浦標準砂につき相対密度を調整した
複数の試料について、次の第１表に示す条件に於いて室
内にてコーン貫入試験を行ない、相対密度との対応関係
を調べた。Meanwhile, one in which the relative density of the measure of the properties of the soil (Dr o) is intended to reflect only tightness of the ground, are known to be very closely related to liquefaction strength. Therefore, a plurality of samples whose relative densities were adjusted with respect to Toyoura standard sand were subjected to a cone penetration test in a room under the conditions shown in the following Table 1 to investigate the correspondence with the relative density.
第２図(a)は以上の実験に基づき、相対密度（Dro）と、
前記先端貫入抵抗と平均主応力の比（qc／σmo′）の関
係を示すもので、また第２図(b)は相対密度（Dro）と、
前記先端貫入抵抗と平均有効主応力の比（qc／σｍ′）
の関係を示すものである。かかる第２図(a)、(b)から、
平均応力として、平均主応力から過剰間隙水圧を減じて
成る平均有効主応力を用いた後者の方が、より強い対応
関係にあること、即ち砂の液状化強度と密接な関係にあ
る相対密度（Dro）は、先端貫入抵抗と、過剰間隙水圧
を考慮した平均有効主応力の比（qc／σｍ′）と良い相
関があることがわかる。 Based on the above experiment, Fig. 2 (a) shows the relative density (Dr o ) and
The relationship between the tip penetration resistance and the average principal stress ratio (qc / σ mo ′) is shown, and FIG. 2 (b) shows the relative density (Dr o ),
Ratio of tip penetration resistance and average effective principal stress (qc / σ m ′)
It shows the relationship of. From FIGS. 2 (a) and (b),
The latter, which uses the average effective principal stress obtained by subtracting the excess pore water pressure from the average principal stress as the average stress, has a stronger correspondence, that is, the relative density (which is closely related to the liquefaction strength of sand ( It can be seen that Dr o ) has a good correlation with the tip penetration resistance and the ratio (qc / σ m ′) of the average effective principal stress considering the excess pore water pressure.
そこで次に、前述した室内試験と同様の試料及び原位置
の地盤に関して、液状化強度と前記比（qc／σmo′）、
（qc／σｍ′）との対応関係を調べた。尚、室内試験の
試料に対する液状化強度は振動三軸試験に基づく繰返し
応力比として表わし、また原位置に於ける液状化強度は
道路橋示方書に基づいた値で表わした。第３図(a)、(b)
は、液状化強度（Rl）に対する、夫々比（qc／
σmo′）、（qc／σｍ′）の関係を示すもので、かかる
図から、前述した相対密度（Dr0）と同様に、液状化強
度（Rl）についても、過剰間隙水圧を考慮している比
（qc／σｍ′）の方が、考慮していない比（qc／σm
o′）よりも良い相関があることがわかる。Then, next, regarding the same sample and in-situ ground as the above-mentioned indoor test, the liquefaction strength and the ratio (qc / σ mo ′),
The correspondence with (qc / σ m ′) was investigated. The liquefaction strength of the sample in the indoor test was expressed as the cyclic stress ratio based on the vibration triaxial test, and the liquefaction strength in the original position was expressed as the value based on the road bridge specification. Figure 3 (a), (b)
Is the ratio (qc /
The relationship between σ mo ′) and (qc / σ m ′) is shown. From this figure, as with the relative density (Dr 0 ) described above, the excess pore water pressure is also taken into consideration for the liquefaction strength (Rl). The ratio (qc / σ m ′) that is not considered is the ratio (qc / σ m ) that is not considered.
It can be seen that there is a better correlation than o ').
以上のことから本発明では、三成分コーン貫入試験を行
ない、過剰間隙水圧を考慮した平均有効主応力を対応関
係に用いることにより、これを考慮しない従来の方法と
比較して、より高い精度で液状化強度を推定し得ること
がわかる。かかる液状化強度と前記比（qc／σｍ′）と
の対応関係は、多数の試験データを統計的に扱うことに
より、一義的な関数式として表わすこともでき、こうす
ることにより、前述した三成分コーン貫入試験による先
端貫入抵抗、周面摩擦抵抗及び過剰間隙水圧から、容易
に、そして即座に液状化強度の推定を行なうことができ
る。例えば第３図(b)に示すデータを最小二乗法により
回帰した場合、次のような式として表わすことができ
る。From the above, in the present invention, by performing a three-component cone penetration test, by using the average effective principal stress in consideration of excess pore water pressure in the correspondence, compared with the conventional method not taking this into account, with higher accuracy. It can be seen that the liquefaction strength can be estimated. The corresponding relationship between the liquefaction strength and the ratio (qc / σ m ′) can be expressed as a unique functional expression by statistically treating a large number of test data. The liquefaction strength can be estimated easily and immediately from the tip penetration resistance, circumferential surface friction resistance and excess pore water pressure by the three-component cone penetration test. For example, when the data shown in FIG. 3 (b) is regressed by the method of least squares, it can be expressed as the following equation.
Rl＝0.0233(qc/σｍ′）0.525……(2) 尚、(2)式に於ける係数や指数の値は、前述した通り、
統計的手法により求められる数値であつて、これらは地
盤の種類やデータ数または液状化強度の表わし方等によ
り異なつてくることは勿論である。Rl = 0.0233 (qc / σ m ′) 0.525 (2) Incidentally, the coefficient and the index value in the equation (2) are as described above.
It is needless to say that these numerical values obtained by a statistical method differ depending on the type of the ground, the number of data, or the way of expressing the liquefaction strength.
ところで、第３図(b)に表わしたデータに関し、液状化
強度の実測値と、(2)式による推定値の残差（実測値−
推定値）を、周面摩擦抵抗と先端貫入抵抗の比（fs/q
c）、即ち摩擦比（Rf）に対して表わすと第４図に示す
関係となる。かかる第４図に於いて、残差は殆んど点線
で囲まれた範囲に在ると見做すことができ、従つて図中
実線で表わした関係によつて残差を代表し得ることがわ
かる。実線で表わした関係によると、残差は、摩擦比が
ある値（図中ａ≒0.5％）を越えると、該摩擦比が大き
くなる程、正の残差が大となり、即ち実測値が推定値よ
りも大となることがわかる。このことから、摩擦比があ
る値よりも大きな時には、該摩擦比に対応する正の補正
量（ΔＲ）を、前記(2)式による液状化強度の推定値に
加えることにより、より精度の高い推定を行なえること
がわかる。定性的には摩擦比が大となるということは、
粒子が細かくなるということであり、前記補正は粒度に
よる補正を表わすものである。前記正の補正量は図示の
データの場合には、次式により表わすことができる。By the way, regarding the data shown in FIG. 3 (b), the residual difference between the measured value of the liquefaction strength and the estimated value by the equation (2) (measured value-
Estimated value) is the ratio of the frictional resistance of the surface to the penetration resistance of the tip (fs / q
c), that is, the friction ratio (Rf), has the relationship shown in FIG. In FIG. 4, it can be considered that the residual is almost in the range surrounded by the dotted line, and therefore, the residual can be represented by the relationship represented by the solid line in the figure. I understand. According to the relationship represented by the solid line, when the friction ratio exceeds a certain value (a≈0.5% in the figure), the larger the friction ratio is, the larger the positive residual is. It turns out that it is larger than the value. From this, when the friction ratio is larger than a certain value, a positive correction amount (ΔR) corresponding to the friction ratio is added to the estimated value of the liquefaction strength according to the equation (2) to obtain higher accuracy. It turns out that an estimate can be made. Qualitatively, the fact that the friction ratio is large means that
This means that the particles become finer, and the correction represents a correction based on the particle size. In the case of the data shown, the positive correction amount can be expressed by the following equation.
尚、(2)式の場合と同様、(3)式に於ける定数は、統計的
手法により求められる手法であつて、これらも地盤の種
類やデータ数または液状化強度の表わし方等により異な
つてくることは勿論である。 As in the case of the equation (2), the constant in the equation (3) is a method obtained by a statistical method, and these are also different depending on the type of the ground, the number of data or the expression of the liquefaction strength. Of course, it comes.
以上のことから、対象とする地盤に対して三成分コーン
貫入試験を行なつて先端貫入抵抗、周面摩擦抵抗及び間
隙水圧を測定して、(1)式により地震時液状化強度を推
定することができる。尚、有効上載圧は次式から求める
ことができるものである。Based on the above, a three-component cone penetration test is conducted on the target ground to measure the tip penetration resistance, circumferential friction resistance, and pore water pressure, and the liquefaction strength during an earthquake is estimated using Equation (1). be able to. The effective loading pressure can be obtained from the following equation.
σＶ′＝γｔ・Zw＋γ′(Z-Zw)……(4) 但し、 σＶ′：有効上載圧 γｔ：地下水面より上の土の単位重量 γ′：地下水面より下の土の単位重量（水中重量） Zw：地表から地下水面までの深度 Ｚ：地表からコーン先端までの深度 （発明の効果） 本発明は以上の通り、三成分コーン貫入試験を行なつて
先端貫入抵抗、周面摩擦抵抗及び過剰間隙水圧を測定
し、先端貫入抵抗と平均応力の比との対応関係から液状
化強度を推定する際、平均応力としては、液状化現象と
密接な関係のある地盤の締まり具合いや透水性と深い関
連性を有する過剰間隙水圧を考慮した平均有効主応力を
導入しているので、これを考慮しない平均主応力を用い
るものと比較して、より精度良く液状化強度の推定を行
なうことができ、また地盤の粒度と密接な関係がある摩
擦比がある値以上の場合、即ち細粒の場合には所定の正
の補正量を前記液状化強度の推定値に加えるようにした
ので、細粒の地盤に対して過小評価することもない。こ
のように本発明は液状化の主要因である土の締まり具
合、粒度分布、地下水位および上載圧等を総合的に組み
入れて液状化強度の推定を行なうことができ、比較的高
い精度での推定を行なえるという効果がある。そして本
発明はこのように比較的高い精度に於ける液状化強度の
推定を行なえるものでありながら、Ｎ値、粒度試験結果
等を用いる推定方法と比較して、ボーリングを伴わない
サウンデイングを行なえば良いので、迅速かつ安価に行
なうことができ、貫入試験機をトラツク等の車両に積載
すれば、簡易で、しかも機動性に富んだ作業を行なうこ
とができるという効果がある。σ V ′ = γ t · Zw + γ ′ (Z-Zw) (4) where σ V ′: Effective loading pressure γ t : Unit weight of soil above water table γ ′: Of soil below water table Unit weight (weight in water) Zw: Depth from the surface to the water table Z: Depth from the surface to the cone tip (Effect of the invention) As described above, the three-component cone penetration test was performed to perform tip penetration resistance and circumference. When measuring the surface friction resistance and excess pore water pressure and estimating the liquefaction strength from the relationship between the tip penetration resistance and the average stress ratio, the average stress is the tightness of the ground, which is closely related to the liquefaction phenomenon. No, since the average effective principal stress considering the excess pore water pressure, which is closely related to the water permeability, is introduced, it is possible to estimate the liquefaction strength more accurately than the method using the average principal stress that does not consider this. Friction that can be performed and is closely related to the grain size of the ground When the ratio is equal to or greater than a certain value, that is, in the case of fine particles, a predetermined positive correction amount is added to the estimated value of the liquefaction strength, so that the ground of fine particles is not underestimated. As described above, the present invention can estimate the liquefaction strength by comprehensively incorporating the soil tightness, the particle size distribution, the groundwater level, the top pressure, etc., which are the main factors of the liquefaction, with a relatively high accuracy. The effect is that estimation can be performed. While the present invention is capable of estimating the liquefaction strength with relatively high accuracy as described above, compared with the estimation method using the N value, the particle size test result, etc., sounding without boring is performed. Since it suffices to carry out the work, it can be carried out quickly and inexpensively, and if the penetration tester is loaded on a vehicle such as a truck, it is possible to perform a simple and highly mobile work.
第１図は本発明に用いる三成分コーン貫入試験機の要部
の一例を示す断面説明図、第２図(a)、(b)は相対密度
と、先端貫入抵抗と平均応力の比との関係、第３図(a)、
(b)は液状化強度と、先端貫入抵抗と平均応力の比との
関係を示すもので、夫々に於いて平均応力として、(a)
は平均主応力、(b)は平均有効主応力を用いたものであ
る。また第４図は、摩擦比に対する、液状化強度の実測
値と推定値の残差との関係を示すものである。 符号１…コーンプローブ、２…ロツド、３…コーン、４
…フイルタ、５…水圧計、６…マトレインゲージ、７…
フリクシヨンスリーブ、８…ストレインゲージ。FIG. 1 is a cross-sectional explanatory view showing an example of a main part of a three-component cone penetration tester used in the present invention, and FIGS. 2 (a) and 2 (b) are relative densities and ratios of tip penetration resistance and average stress. Relationship, Figure 3 (a),
(b) shows the relationship between liquefaction strength and the ratio of tip penetration resistance and average stress.
Is the average principal stress, and (b) is the average effective principal stress. Further, FIG. 4 shows the relationship between the actual value of the liquefaction strength and the residual difference of the estimated value with respect to the friction ratio. Reference numeral 1 ... Cone probe, 2 ... Rod, 3 ... Cone, 4
… Filters, 5… Water pressure gauges, 6… Matrain gauges, 7…
Friction sleeve, 8 ... Strain gauge.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 土質工学会試験法改訂委員会編「土質調 査法」（昭45−12−10）社団法人土質工学 会Ｐ．106 大橋完「土質と基礎」（1977−５−30) 槇書店Ｐ．20 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliography Soil Engineering Society Test Method Revision Committee, “Soil Survey Method” (Sho 45-12-10) P.E. 106 Ohashi Kan “Soil and Basics” (1977-5-30) Maki Shoten P. 20
Claims (2)
試験を行なって先端貫入抵抗、周面摩擦抵抗及び間隙水
圧を測定し、有効上載圧から求めた平均主応力から、前
記間隙水圧より静水圧を減じて成る過剰間隙水圧を減じ
て平均有効主応力を求め、前記先端貫入抵抗と該平均有
効主応力の比と、液状化強度の対応関係により対象地盤
の地震時液状化強度を推定することを特徴とする地盤の
地震時液状化強度の推定方法1. A three-component cone penetration test is conducted on a target ground to measure tip penetration resistance, circumferential friction resistance and pore water pressure, and from the average principal stress obtained from effective loading pressure, Estimate the liquefaction strength of the target ground during an earthquake from the relationship between the tip penetration resistance and the average effective principal stress, and the liquefaction strength Method for estimating liquefaction strength of ground during earthquakes
試験を行なって先端貫入抵抗、周面摩擦抵抗及び間隙水
圧を測定し、有効上載圧から求めた平均主応力から、前
記間隙水圧より静水圧を減じて成る過剰間隙水圧を減じ
て平均有効主応力を求め、前記先端貫入抵抗と該平均有
効主応力の比と、液状化強度の対応関係により対象地盤
の地震時液状化強度を推定する際、前記周面摩擦抵抗、
先端貫入抵抗とから求められる摩擦比がある値よりも大
きな時には、該摩擦比に対応する正の補正量を前記推定
液状化強度に加えることを特徴とする地盤の地震時液状
化強度の推定方法2. A three-component cone penetration test is conducted on the target ground to measure tip penetration resistance, circumferential friction resistance and pore water pressure, and from the average principal stress obtained from effective loading pressure, Estimate the liquefaction strength of the target ground during an earthquake from the relationship between the tip penetration resistance and the average effective principal stress, and the liquefaction strength When doing, the peripheral frictional resistance,
When the friction ratio obtained from the tip penetration resistance is larger than a certain value, a positive correction amount corresponding to the friction ratio is added to the estimated liquefaction strength to estimate the liquefaction strength during earthquake of the ground.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10635886A JPH0663218B2 (en) | 1986-05-09 | 1986-05-09 | Method of estimating liquefaction strength of ground during earthquake |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10635886A JPH0663218B2 (en) | 1986-05-09 | 1986-05-09 | Method of estimating liquefaction strength of ground during earthquake |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62264207A JPS62264207A (en) | 1987-11-17 |
| JPH0663218B2 true JPH0663218B2 (en) | 1994-08-22 |
Family
ID=14431528
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10635886A Expired - Lifetime JPH0663218B2 (en) | 1986-05-09 | 1986-05-09 | Method of estimating liquefaction strength of ground during earthquake |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0663218B2 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002317431A (en) * | 2001-04-20 | 2002-10-31 | Nishimatsu Constr Co Ltd | Horizontal penetration testing device and penetration testing method |
| JP4458465B2 (en) * | 2004-02-17 | 2010-04-28 | 応用地質株式会社 | Ground investigation method and device by measuring excess pore water pressure during impact penetration |
| JP4709631B2 (en) * | 2004-10-29 | 2011-06-22 | 株式会社竹中工務店 | Liquefaction strength curve estimation device and liquefaction strength curve estimation program |
| JP2014005612A (en) * | 2012-06-22 | 2014-01-16 | Maeda Corp | Quality confirmation method and quality confirmation device for improved ground |
| JP6256880B2 (en) * | 2014-06-10 | 2018-01-10 | 応用地質株式会社 | Ground survey method and ground survey device |
| JP2016156209A (en) * | 2015-02-25 | 2016-09-01 | 株式会社地盤試験所 | Foundation liquefaction determination method |
| JP7190692B2 (en) * | 2018-10-02 | 2022-12-16 | 株式会社奥村組 | Pile hole forming device |
| JP7185871B2 (en) * | 2018-10-02 | 2022-12-08 | 株式会社奥村組 | Pile hole forming device |
| JP7193846B2 (en) * | 2019-02-28 | 2022-12-21 | 地方独立行政法人北海道立総合研究機構 | Method and apparatus for estimating dry matter density of silage |
-
1986
- 1986-05-09 JP JP10635886A patent/JPH0663218B2/en not_active Expired - Lifetime
Non-Patent Citations (2)
| Title |
|---|
| 土質工学会試験法改訂委員会編「土質調査法」（昭４５−１２−１０）社団法人土質工学会Ｐ．１０６ |
| 大橋完「土質と基礎」（１９７７−５−３０）槇書店Ｐ．２０ |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62264207A (en) | 1987-11-17 |
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