JP6159089B2 - Soil judgment method - Google Patents
Soil judgment method Download PDFInfo
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- JP6159089B2 JP6159089B2 JP2013003853A JP2013003853A JP6159089B2 JP 6159089 B2 JP6159089 B2 JP 6159089B2 JP 2013003853 A JP2013003853 A JP 2013003853A JP 2013003853 A JP2013003853 A JP 2013003853A JP 6159089 B2 JP6159089 B2 JP 6159089B2
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Description
本発明は、スクリューポイントを地中に回転貫入する試験により得られる各種測定データに基づいて土質を判定する方法に関する。 The present invention relates to a method for determining soil quality on the basis of various measurement data obtained by a test of rotating a screw point into the ground.
従来から、ロータリーパーカッションドリルによる貫入試験において、ロッドに作用する荷重及びトルクを測定し、これら測定値に基づいて土質を調査する方法が知られている(特許文献1)。この土質調査は、試験パラメータとしてトルク増加勾配At(At=回転トルク増分/荷重増分)を用いており、所定の深度毎にトルク増加勾配Atの分布を求め、土質判別の境界値を求めることにより、粘性土と砂質土を判別しようとするものである。 Conventionally, in a penetration test using a rotary percussion drill, a method of measuring a load and torque acting on a rod and investigating soil properties based on these measured values is known (Patent Document 1). This soil investigation uses a torque increase gradient At (At = rotational torque increment / load increment) as a test parameter, and obtains a distribution of the torque increase gradient At for each predetermined depth and obtains a boundary value for soil determination. It is intended to distinguish between viscous soil and sandy soil.
しかしながら、上記貫入試験による試験パラメータは、粘性土及び砂質土の双方において、増加勾配を示す。このため、土質判別の境界値(基準値)を求めなければならないので、判別手順が複雑化していた。 However, the test parameters from the penetration test show an increasing gradient in both viscous and sandy soils. For this reason, since the boundary value (reference value) for soil determination must be obtained, the determination procedure is complicated.
本発明の土質判定方法は、上記課題に鑑みて創成されたものであり、貫入試験により取得した試験パラメータから容易に土質を判定することが可能な土質判定方法を提供することを目的とする。 The soil quality determination method of the present invention was created in view of the above problems, and an object thereof is to provide a soil quality determination method capable of easily determining soil quality from test parameters acquired by an penetration test.
本発明は、先端に貫入体を有する貫入ロッドを地中に回転貫入し、段階的に貫入ロッドに負荷する荷重Wを変化させながら、貫入ロッドの回転トルクT及び貫入量Stを測定する貫入試験において、累積貫入量ΣStの変化に対する回転トルクTの変化の割合を示す試験パラメータdT/dΣStに基づいて砂質土を判別することを特徴とする。
The present invention is a penetration test in which a penetrating rod having a penetrating body at the tip is rotationally penetrated into the ground, and the rotational torque T and penetration amount St of the penetrating rod are measured while changing the load W applied to the penetrating rod in stages. in, characterized in that the sandy soil to another determine on the basis of test parameters dT / dΣSt indicating the rate of change of the torque T with respect to a change in the cumulative penetration amount ShigumaSt.
本発明の土質判定方法に用いる試験パラメータは、砂質土において顕著な増加傾向を示すので、一目で土質を判定することができる。 Since the test parameters used in the soil quality determination method of the present invention show a marked increase in sandy soil, the soil quality can be determined at a glance.
まず、図1乃至図3は、本発明に用いる試験パラメータ(回転トルクT)を取得するための貫入試験を示す。この貫入試験は、ロッド2の先端に、貫入体の一例であるスクリューポイント3を備えて成る貫入ロッド1を地中に回転貫入するものであり、試験深度区間0.25mに対して最大7段階(250N,375N,500N,625N,750N,875N,1kN)の荷重Wを錘4により載荷しながら、貫入ロッド1の1回転あたりの回転トルクT及び貫入量Stを測定する。具体的には、図1及び図3に示すように、まず、初期荷重250Nを貫入ロッド1に載荷した状態で1回転貫入させる(S01)。このとき、貫入量Stが25cmに達していない場合(S02)には、次の荷重375Nを貫入ロッド1に載荷して1回転貫入させる(S03)。1回転毎に荷重125Nを加算し、累積貫入量ΣStが0.25mに到達するまで回転貫入する。 First, FIG. 1 thru | or FIG. 3 shows the penetration test for acquiring the test parameter (rotation torque T) used for this invention. In this penetration test, the penetration rod 1 provided with a screw point 3 as an example of a penetration body at the tip of the rod 2 is rotated and penetrated into the ground, and a maximum of seven stages with respect to a test depth section of 0.25 m. (250N, 375N, 500N, 625N , 750N, 875N, 1kN) while loading by weight 4 a load W of, measuring the torque T and the penetration amount S t per one rotation of the penetration rod 1. Specifically, as shown in FIGS. 1 and 3, first, the initial load 250N is made to penetrate once in a state of being loaded on the penetration rod 1 (S01). In this case, if the penetration amount S t has not reached the 25 cm (S02), and loading the next load 375N to penetration rod 1 rotated once penetration (S03). Adds a load 125N for each rotation, the cumulative penetration amount [sigma] s t is rotated penetrate until it reaches the 0.25 m.
また、図2及び図3に示すように、最大荷重1kNを載荷した状態において(S04)、累積貫入量ΣStが0.25mに到達していない場合は、最大荷重1kNを載荷した状態で累積貫入量ΣStが0.25mに到達するまで回転貫入を繰り返す(S05)。そして、最初の試験深度区間(深度0m〜0.25m)の測定が終了すると、回転貫入を停止し(S06)、次の試験深度区間(深度0.25m〜0.5m)を測定する。このような場合には、試験区間における測定ポイントは、7箇所以上となる。反対に、最大荷重1kNを載荷する前に累積貫入量ΣStが0.25mに到達した場合には、図1に示すように、測定ポイントは、1乃至6箇所となる。 Further, as shown in FIGS. 2 and 3, in a state where the loading of the maximum load 1kN (S04), the cumulative penetration amount [sigma] s t does not reach the 0.25m, the cumulative while loading the maximum load 1kN penetration amount [sigma] s t is repeated rotation penetration to reach the 0.25 m (S05). Then, when the measurement of the first test depth section (depth 0 m to 0.25 m) is completed, the rotation penetration is stopped (S06), and the next test depth section (depth 0.25 m to 0.5 m) is measured. In such a case, there are seven or more measurement points in the test section. Conversely, if the cumulative penetration amount [sigma] s t before loading the maximum load 1kN reaches 0.25m, as shown in FIG. 1, the measurement point is 1 to 6 places.
ところで、上記貫入試験による測定値は、ロッド2の周面摩擦による影響を受けているため、スクリューポイント3に作用する荷重W及び回転トルクが測定できていない。そこで、0.25m貫入する毎に貫入ロッド1を1cm引き上げて回転させ(S07)、このときの回転トルクTmを測定し(S08)、元の位置へ戻す(S09)。この回転トルクTmは、ロッド2の周面摩擦の算定に用いる。算定方法としては、ロッド2に作用する鉛直及び水平方向の周面摩擦をそれぞれWf、Tfとした場合、スクリューポイント3に作用する荷重W及び回転トルクTは、貫入ロッド1全体に作用する荷重Wa及びTaを用いて次式で表される。
Wa=Wf+W、Ta=Tf+T
したがって、スクリューポイント3に作用する荷重W及び回転トルクTは、次式で表される。
W=Wa−Wf、T=Ta−Tf
以下の説明においては、貫入ロッド1の回転トルクTは、ロッド2の周面摩擦を考慮したものとする。また、上記貫入試験は、貫入ロッド1の一回転あたりの回転トルクTについて、最大値Tmax、最小値Tmin及び平均値T(−)も測定している。
By the way, since the measured value by the penetration test is influenced by the circumferential friction of the rod 2, the load W and the rotational torque acting on the screw point 3 cannot be measured. Therefore, every time 0.25 m penetrates, the penetrating rod 1 is pulled up by 1 cm and rotated (S07), and the rotational torque Tm at this time is measured (S08) and returned to the original position (S09). This rotational torque Tm is used for calculating the circumferential friction of the rod 2. As a calculation method, assuming that the vertical and horizontal circumferential friction acting on the rod 2 is Wf and Tf, respectively, the load W and the rotational torque T acting on the screw point 3 are the load Wa acting on the entire penetration rod 1. And Ta are used to express the following equation.
Wa = Wf + W, Ta = Tf + T
Therefore, the load W and the rotational torque T acting on the screw point 3 are expressed by the following equations.
W = Wa-Wf, T = Ta-Tf
In the following description, it is assumed that the rotational torque T of the penetrating rod 1 takes into account the circumferential friction of the rod 2. In the penetration test, the maximum value T max , the minimum value T min, and the average value T (−) are also measured for the rotational torque T per rotation of the penetration rod 1.
本発明の土質判定方法では、上記貫入試験による測定値に基づいて、試験パラメータとしてdT/dΣStを設定する。この試験パラメータdT/dΣStは、累積貫入量ΣStの変化に対する回転トルクTの変化の割合を示すものである。具体的には、試験パラメータdT/dStは、図4に示すように、縦軸に回転トルクT、横軸に試験区間における総貫入量ΣStを設定したグラフに示す近似線の傾きである。粘性土、ローム及び腐植土については、試験パラメータdT/dΣStは一定あるいは僅かな増加傾向を示すのに対して、砂質土では顕著な増加傾向を示す。このため、砂質土を一目で判定することができる。 In the soil determination method of the present invention, dT / dΣSt is set as a test parameter based on the measured value by the penetration test. This test parameter dT / dΣSt indicates the ratio of the change in the rotational torque T to the change in the cumulative penetration amount ΣSt. Specifically, as shown in FIG. 4, the test parameter dT / dSt is an inclination of an approximate line shown in a graph in which the vertical axis indicates the rotational torque T and the horizontal axis indicates the total penetration amount ΣSt in the test section. For viscous soils, loams and humus soils, the test parameter dT / dΣSt shows a constant or slight increase trend, whereas sandy soils show a significant increase trend. For this reason, sandy soil can be determined at a glance.
1 貫入ロッド
2 ロッド
3 スクリューポイント
4 錘
1 Intrusion rod 2 Rod 3 Screw point 4 Weight
Claims (1)
累積貫入量ΣStの変化に対する回転トルクTの変化の割合を示す試験パラメータdT/dΣStに基づいて砂質土を判別することを特徴とする土質判定方法。 In the penetration test to measure the rotational torque T and the penetration amount St of the penetration rod while changing the load W applied to the penetration rod step by step through the penetration rod having a penetration body at the tip.
Soil determination method characterized by the sandy soil to another determine on the basis of test parameters dT / dΣSt indicating the rate of change of the torque T with respect to a change in the cumulative penetration amount ShigumaSt.
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