JP4091819B2 - Penetration testing machine and automatic calculation method of converted N value - Google Patents

Description

数１における土質係数Ａｓｗ、Ｂｓｗはそれぞれ土質に応じて与えられるものであり、これまでの経験則から、次のように定められている。
粘性土の場合：Ａｓｗ＝０．０３，Ｂｓｗ＝０．０５
砂質土の場合：Ａｓｗ＝０．０２，Ｂｓｗ＝０．０６７
この土質係数Ａｓｗ、Ｂｓｗを決定するための土質は、貫入試験中、作業者が都度聴取した貫入ロッドを伝播してくる音によって決定されていた。
【０００８】
【発明が解決しようとする課題】
上記従来の貫入試験機による貫入試験においては、貫入試験中に貫入ロッドを伝播されてくる音は、作業者が都度聴取することによって取得される。このため、作業者の熟練度や日毎のコンディション、あるいは各作業者の身体的な固有特性に応じて得られる音にはばらつきが生じてしまう。また、得られた音は、制御ユニットで極めて綿密かつ高精度に得られるＮｓｗ値および荷重値に比較して著しく詳細さおよび精度が劣る。さらに、貫入試験は、通常屋外で行われるため、例えば貫入試験機に電源を供給するための発電機の作動音など、周囲の騒音が非常に多く、貫入ロッドを伝わる音を作業者が正確に聴取することは非常に困難である。これらのことから、従来は、正しい換算Ｎ値を算出して地盤硬度を判定することができなくなってしまう等の問題が発生していた。
【０００９】
【課題を解決するための手段】
本発明は上記課題に鑑みて創成されたものであり、所定の荷重が負荷されるとともに必要に応じて回転が付与されて地中に貫入される貫入部材と、前記貫入部材が地中に貫入されるのにともなって当該貫入部材を伝播されてくる音を検出可能な音検出手段と、前記音検出手段によって検出された所定区間の音響データからヒストグラムを生成し、このヒストグラムに予め設定された閾値を適用してこれを超える領域の面積に応じて当該区間の土質を判定する土質判定部と、前記土質判定部によって判定された土質に応じて予め用意された換算Ｎ値の演算に必要な土質係数を取得し、これを用いて換算Ｎ値の演算処理を行う演算処理部とを備えていることを特徴とする。なお、前記演算処理部は、土質判定部によって判定された土質に応じて、荷重値Ｗｓｗに対応する土質係数Ａｓｗと、回転貫入時の１ｍ当たりの貫入部材の半回転数Ｎｓｗに対応する土質係数Ｂｓｗとを取得し、換算Ｎ値＝Ａｓｗ・Ｗｓｗ＋Ｂｓｗ・Ｎｓｗにより換算Ｎ値を演算することが望ましい。
【００１０】
また、本発明は、貫入部材を地中に貫入した時に当該貫入部材を伝播される音を音検出手段により検出し、この音検出手段によって検出された所定区間の音響データからヒストグラムを生成し、このヒストグラムに予め設定された閾値を適用してこれを超える領域の面積に応じて当該区間の土質を判定し、この判定結果に応じて演算処理部により換算Ｎ値の算出に必要な土質係数を取得して換算Ｎ値を演算する換算Ｎ値の自動算出方法でもある。
【００１１】
【発明の実施の形態】
以下、図面に基づき本発明の実施の形態を説明する。図１において、１は貫入試験機であり、その基本的な構成は、上記従来の技術で紹介した特開平８−２９２１４１号公報によって公知の貫入試験機と同様である。よって、ここでは、特開平８−２９２１４１号公報によって公知の貫入試験機と相違する構成について説明することとし、従来の技術の欄で既に紹介した構成部品には同様の符号を付し、その詳しい説明は省略することとする。
【００１２】
本貫入試験機１の載荷台４には音検出手段１３が取り付けられており、この音検出手段１３は、貫入ロッド７を地中に貫入した時に当該貫入ロッド７を伝播する音に応じた電気信号を出力するように構成されている。この音検出手段１３は、貫入ロッド７を伝播してきた音による載荷台４の振動を直接検出するタイプ（以下、直接検出型という）のもの、あるいは貫入ロッド７を伝播する音が空中伝播される際の空気振動を検出するタイプ（以下、間接検出型という）のもの等、様々なタイプのものを選択・採用することができる。ちなみに、直接検出型のものとしては、圧電セラミックセンサ等の圧電素子を利用したセンサや磁歪センサ等が採用でき、また、間接検出型のものとしては、集音マイク等が採用できる。但し、間接検出型の音検出手段１３によって音を検出した場合、周囲の騒音も取り込まれるため、間接検出型のものを採用した場合には、後述の土質判定部１５等に騒音要素を除去する機能を持たせておく必要がある。これに対し、直接検出型のものは貫入ロッド７を伝播する音による貫入試験機自体の振動を検出するものであるため、周囲の騒音の影響を受け難い。このため、本実施の形態では、音検出手段１３として直接検出型の圧電セラミックセンサが採用されており、貫入ロッド７からチャック５を経由して空中伝播することなく載荷台４に伝えられる音響振動を検出するようになっている。
【００１３】
前記音検出手段１３は、貫入試験機１を制御する制御ユニット１４に備えられた土質判定部１５に接続されている。その他、制御ユニット１４は、演算処理部１６、昇降モータ駆動部１７、チャックモータ駆動部１８、パウダブレーキ制御部１９（図面ではＰＢ制御部と表記してある）、速度検出部２０、半回転数検出部２１、記憶部２２、入力部２３を備える。
【００１４】
昇降モータ駆動部１７とチャックモータ駆動部１８は、演算処理部１６からの指令を受けて昇降モータ１２、チャックモータ６の駆動制御を行う。また、パウダブレーキ制御部１９は、演算処理部１６からの指令を受けてパウダブレーキ１１への負荷電流を調節する。これにより、パウダブレーキ１１の発生する制動力が増減され、以て貫入ロッド７に負荷される荷重が変更される。さらに、速度検出部２０は、センサ１０の出力信号（パルス信号）を得て、これから単位時間当たりのパルス数（貫入速度）を求める。また、半回転検出部２１は、回転駆動源６が駆動している時、チャック５の回転回数を検出するように配置されるセンサ手段（図示せず）の信号から貫入ロッド７の半回転数を割り出すように構成されている。さらに、記憶部２２は、土質判定に必要な閾値類、上記土質に応じた土質係数Ａｓｗ，Ｂｓｗ等の各種パラメータ、各種制御プログラム等が予め記憶保持している。また、入力部２３は、試験開始指令入力、試験中断指令入力、任意設定パラメータの入力等を行うための入力ボタンおよびキー（何れも図示せず）を備えて成る。
【００１５】
上記貫入試験機１は、上述の特開平８−２９２１４１号公報に示された貫入試験機と同様の動作により、日本工業規格Ａ１２２１のスウェーデン式サウンディング試験方法に準じた方法でサウンディング試験を行う。その間、上述の通り、貫入ロッド７の貫入条件が変更される毎に貫入量、Ｎｓｗ値、荷重値が取得される。貫入量は、速度検出部２０によってカウントされたセンサ１０のパルス数の総計から、Ｎｓｗ値は、半回転数検出部２１によって割り出された半回転数から、荷重値はパウダブレーキ制御部１９によってパウダブレーキ１１に与えられている負荷電流値から、それぞれ演算処理部１６において演算されるものである。また、スクリューポイント７ｂが各土層に貫入される際、その土層の土質に応じた音（スクリューポイント７ｂと土、砂又は礫等との接触による音）が発生するが、この音（振動）はロッド部７ａを伝播されて載荷台４に至り、音検出手段１３によって検出されて土質判定部１５に送られる。
【００１６】
土質判定部１５は、図２に示すように、音検出手段１３の出力信号（以下、音響データという）群ＳＤについて、前述の貫入量、Ｎｓｗ値および荷重値が取得された区間Ｓ（ｎ）（ｎは任意の正数，以下同じ）における音響データを全てサンプリングする。そして、図２の下段に示すように、各音響データの大きさｆ（ｘ）（ｘは任意の正数）の二乗値とデータ数とで表されるヒストグラムを生成する。さらに、このヒストグラムにおいて、予め設定した閾値を超えている領域の面積Ａ（ｎ）を求め、その面積Ａ（ｎ）がヒストグラム全体の面積に占める割合に応じて、その区間における土質が砂質土であるか粘性土であるかを判定する。一般に砂質土の方が粘性土よりも大きな音を発生するため、前述のヒストグラムおいて閾値Ｔを超える領域の面積が増大する。つまり、ヒストグラムにおいて閾値Ｔを超える領域の面積の全体に占める割合が境界値よりも大きい場合（例えば、１０％以上の場合）には、砂質土と判定され、小さい場合（例えば、１０％未満の場合）には粘性土と判定される。
【００１７】
前述のようにして土質が判定されると、その結果に応じた係数が記憶部２２から演算処理部１６に読み込まれる。また、演算処理部１６には、対応する荷重および１ｍ当たりの半回転数Ｎｓｗも読み込まれ、これらから上記数１を用いて換算Ｎ値が計算され、その結果が記憶部２２に格納される。このように、貫入試験の進行にともなって順次換算Ｎ値が求められ記憶部２２に格納されていく。従って、貫入試験終了後、得られた試験データから換算Ｎ値を求める必要がなく、貫入試験後の作業者の負担を軽減することができる。
【００１８】
なお、以上の説明では、土質に応じて換算Ｎ値の演算に利用する土質係数を決定する例について紹介したが、本発明の技術的思想は、その他、土質に応じて演算に使用するデータを選択する必要がある場合にも適用できるものであって、上記の例に限定されるものではない。また、土質判定部１５による土質判定処理方式については、先に提案されている特願２００１−３２２４９２に記載の方式を音響データの前処理に採用しておくことで、得られる土質判定用の音響データはより高精度のものとなる。
【００１９】
【発明の効果】
本発明は、貫入ロッドを伝播される音を検出する音検出手段と、この音検出手段によって検出された音響データに基づいて土質を判定する土質判定部と、この土質判定部によって判定された土質に応じて演算処理に必要なデータを選択取得して所定の演算処理を行う演算処理部とを備えているものである。このため、周囲の騒音、作業者の熟練度やコンディション等の影響を受けることなく、音検出手段により綿密かつ高精度に音響データを得ることが可能となる。そして、この音響データから土質を判定し、この土質判定結果に応じたデータを選択して正確な演算処理結果を得ることができる。特に換算Ｎ値の演算処理においては、正しい換算Ｎ値を算出して正確な地盤硬度を判定することが可能になるという効果が得られる。また、従来、作業者が貫入試験後に行っていた処理が自動化されるため、試験後における作業者の負担軽減を実現することが可能になる等の利点もある。
【図面の簡単な説明】
【図１】本発明に係る貫入試験機の概略説明図である。
【図２】土質判定部において生成されるヒストグラムの一例を示す説明図である。
【図３】従来の貫入試験機の正面図である。
【図４】従来の貫入試験機の要部拡大一部切欠断面図である。
【符号の説明】
１ 貫入試験機
２ 錘
３ 支柱
４ 載荷台
５ チャック
７ 貫入ロッド
７ａ ロッド部
７ｂ スクリューポイント
８ チェーン部材
９ スプロケット
１１ パウダブレーキ
１３ 音検出手段
１４ 制御ユニット
１５ 土質判定部
１６ 演算処理部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a penetration testing machine that automatically performs calculation processing such as converted N value that requires soil information for calculation when performing a penetration test for investigating hardness and softness of the ground, and an automatic calculation method for converted N value. Is.
[0002]
[Prior art]
In various production sites, work sites, etc., it is known to know the state of equipment used, the state of work, etc. by identifying the operating sound of the equipment used, the contact sound between the work and tools, and the like. As a specific example, we will introduce a ground investigation test conducted to know the earth strength of the planned construction site of the building. This ground investigation test includes various penetration tests such as standard penetration test, Dutch double-pipe cone penetration test, Swedish sounding test, and boring test. These penetration tests are conducted using a dedicated ground survey machine. This is what is being done. Among such ground survey machines, a particularly popular penetration test machine is disclosed in Japanese Patent Application Laid-Open No. 8-292141. This penetration testing machine generally has the following configuration.
[0003]
As shown in FIG. 3 and FIG. 4, the conventional penetration testing machine 1 ′ has a loading table 4 that can load a weight 2 having a predetermined weight and can be moved up and down along the column 3. A chuck 5 is arranged. The chuck 5 is rotated by being driven by a motor 6 (hereinafter referred to as a chuck motor 6), and the penetration rod 7 is held by the chuck 5 so as to rotate integrally. The penetrating rod 7 includes a rod-shaped rod portion 7a that can be added and a drill-like screw point 7b attached to the tip of the rod portion 7a, and is an example of a penetrating member according to the claims. Is.
[0004]
Further, a chain member 8 is provided on the column 3 so as to extend linearly, and a sprocket 9 rotatably attached to the loading platform 4 is meshed with the chain member 8. By detecting the rotation of the sprocket 9 by the sensor 10, the lowering amount of the loading table 4, that is, the penetration amount (penetration depth) of the penetration rod 7 can be determined from the signal. A method for indexing the penetration amount of the penetration rod 7 is also known from Japanese Patent Application Laid-Open No. 9-111745. The sprocket 9 is configured to be braked by the powder brake 11, and the load applied to the penetrating rod 7 is increased or decreased according to the magnitude of the braking force of the powder brake 11. Reference numeral 12 denotes a lifting motor for rotationally driving the sprocket 9 to create a lifting operation of the loading table 4.
[0005]
The penetration testing machine 1 automatically performs a sounding test according to the Swedish sounding test method of Japanese Industrial Standard A1221. In the test, a load (increase / decrease every 250 N, maximum 1 KN) due to the weight of the loading platform 4 is applied to the penetration rod 7, and rotation is applied to the penetration rod 7 as necessary. Penetration inside.
[0006]
In the process of penetrating rod 7 penetrating into the ground, the penetrating speed of penetrating rod 7 changes according to the soil quality. Therefore, such as rotation application / stop, load change, etc. Intrusion conditions are changed. Each time this penetration condition is changed, the penetration depth of the penetration rod 7, the half rotation number of the penetration rod 7 (the number of revolutions counted as one revolution of the penetration rod 7), and the load value Wsw are controlled by a control unit (not shown). Z). The control unit obtains a half rotation number per 1 m (hereinafter referred to as Nsw value) from the obtained half rotation number. The detailed structure, operation, and effects of the penetration testing machine 1 'are the same as those of the above-mentioned Japanese Patent Application Laid-Open No. 8-292141.
[0007]
Conventionally, after the penetration test is finished, an evaluation index value of ground hardness called a converted N value is obtained by Equation 1 using the obtained load value Wsw, half rotation speed Nsw and soil coefficient at each penetration depth, and each penetration is obtained. The ground hardness at the depth was judged.
[Expression 1]

The soil coefficient Asw and Bsw in Equation 1 are given according to the soil quality, respectively, and are determined as follows based on empirical rules so far.
For clay soil: Asw = 0.03, Bsw = 0.05
For sandy soil: Asw = 0.02, Bsw = 0.067
The soil quality for determining the soil quality factors Asw and Bsw was determined by the sound propagating through the penetration rod that the operator listened to during the penetration test.
[0008]
[Problems to be solved by the invention]
In the penetration test by the conventional penetration test machine, the sound propagated through the penetration rod during the penetration test is acquired by listening to the operator each time. For this reason, variation occurs in the sound obtained according to the skill level of the worker, the condition of each day, or the physical characteristic of each worker. In addition, the sound obtained is significantly inferior in detail and accuracy as compared with the Nsw value and load value obtained by the control unit with great precision and high accuracy. Furthermore, since the penetration test is usually performed outdoors, there is a lot of ambient noise, such as the operating noise of the generator to supply power to the penetration tester, and the operator accurately hears the sound transmitted through the penetration rod. It is very difficult to listen. For these reasons, conventionally, there has been a problem that it is impossible to determine the ground hardness by calculating a correct converted N value.
[0009]
[Means for Solving the Problems]
The present invention has been created in view of the above problems, and a penetrating member that is loaded with a predetermined load and is rotated as necessary and penetrates into the ground, and the penetrating member penetrates into the ground. As a result, a sound detection means capable of detecting the sound propagated through the penetrating member, and a histogram is generated from the acoustic data of a predetermined section detected by the sound detection means, and the histogram is preset. Necessary for calculating a soil N determination unit that determines the soil quality of the section according to the area of the region that exceeds the threshold by applying a threshold, and a converted N value prepared in advance according to the soil determined by the soil determination unit And a calculation processing unit that acquires a soil coefficient and performs calculation processing of the converted N value using the soil coefficient . In addition, according to the soil determined by the soil determination unit , the arithmetic processing unit performs a soil coefficient Asw corresponding to the load value Wsw and a soil coefficient corresponding to the half rotation number Nsw of the penetrating member per meter at the time of rotation penetration. It is desirable to obtain Bsw and calculate the converted N value by the converted N value = Asw · Wsw + Bsw · Nsw .
[0010]
Further, the present invention detects sound propagated through the penetrating member when penetrating into the ground by sound detecting means , generates a histogram from acoustic data of a predetermined section detected by the sound detecting means , A preset threshold value is applied to this histogram, and the soil quality of the section is determined according to the area of the region exceeding the threshold, and the soil processing coefficient necessary for calculating the converted N value is calculated by the arithmetic processing unit according to the determination result. It is also an automatic calculation method of a converted N value that is obtained and calculated as a converted N value.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a penetration tester, and the basic configuration thereof is the same as that of a known penetration tester according to Japanese Patent Laid-Open No. 8-292141 introduced in the above-mentioned prior art. Therefore, here, the configuration different from the known penetration tester will be described in Japanese Patent Application Laid-Open No. 8-292141, and the components already introduced in the column of the prior art will be denoted by the same reference numerals and detailed description thereof will be given. The description will be omitted.
[0012]
A sound detection means 13 is attached to the loading table 4 of the penetration testing machine 1, and this sound detection means 13 is an electric according to the sound propagating through the penetration rod 7 when the penetration rod 7 penetrates into the ground. It is configured to output a signal. The sound detection means 13 is of a type that directly detects vibration of the loading table 4 due to sound that has propagated through the penetrating rod 7 (hereinafter referred to as direct detection type), or a sound that propagates through the penetrating rod 7 is propagated in the air. Various types can be selected and adopted, such as a type that detects air vibrations (hereinafter referred to as an indirect detection type). Incidentally, as a direct detection type, a sensor using a piezoelectric element such as a piezoelectric ceramic sensor, a magnetostrictive sensor, or the like can be adopted. As an indirect detection type, a sound collecting microphone or the like can be adopted. However, when the sound is detected by the indirect detection type sound detection means 13, ambient noise is also taken in. Therefore, when the indirect detection type is adopted, a noise element is removed to the soil determination unit 15 or the like described later. It is necessary to have a function. On the other hand, since the direct detection type is for detecting the vibration of the penetration tester itself due to the sound propagating through the penetration rod 7, it is hardly affected by ambient noise. For this reason, in the present embodiment, a direct detection type piezoelectric ceramic sensor is employed as the sound detection means 13, and the acoustic vibration transmitted from the penetrating rod 7 to the loading table 4 without propagating in the air via the chuck 5. Is supposed to be detected.
[0013]
The sound detection means 13 is connected to a soil determination unit 15 provided in a control unit 14 that controls the penetration testing machine 1. In addition, the control unit 14 includes an arithmetic processing unit 16, a lift motor driving unit 17, a chuck motor driving unit 18, a powder brake control unit 19 (denoted as a PB control unit in the drawing), a speed detection unit 20, and a half rotation speed. A detection unit 21, a storage unit 22, and an input unit 23 are provided.
[0014]
The lift motor drive unit 17 and the chuck motor drive unit 18 perform drive control of the lift motor 12 and the chuck motor 6 in response to a command from the arithmetic processing unit 16. In addition, the powder brake control unit 19 receives a command from the arithmetic processing unit 16 and adjusts the load current to the powder brake 11. As a result, the braking force generated by the powder brake 11 is increased or decreased, and the load applied to the penetrating rod 7 is changed. Furthermore, the speed detection unit 20 obtains an output signal (pulse signal) of the sensor 10 and obtains the number of pulses per unit time (penetration speed) therefrom. The half-rotation detection unit 21 also detects the half-rotation speed of the penetrating rod 7 from a signal of sensor means (not shown) arranged to detect the number of rotations of the chuck 5 when the rotational drive source 6 is driven. Is configured to figure out. Furthermore, the storage unit 22 stores and holds in advance thresholds necessary for soil determination, various parameters such as soil coefficients Asw and Bsw corresponding to the soil, various control programs, and the like. The input unit 23 includes an input button and a key (none of which are shown) for inputting a test start command, inputting a test interruption command, inputting an arbitrarily set parameter, and the like.
[0015]
The penetration tester 1 performs a sounding test by a method similar to the Swedish type sounding test method of Japanese Industrial Standard A1221, by the same operation as the penetration tester disclosed in the above-mentioned JP-A-8-292141. Meanwhile, as described above, the penetration amount, the Nsw value, and the load value are acquired every time the penetration condition of the penetration rod 7 is changed. The penetration amount is obtained from the total number of pulses of the sensor 10 counted by the speed detection unit 20, the Nsw value is obtained from the half rotation number determined by the half rotation number detection unit 21, and the load value is obtained by the powder brake control unit 19. From the load current value given to the powder brake 11, each is calculated in the calculation processing part 16. Further, when the screw point 7b penetrates into each soil layer, a sound corresponding to the soil quality of the soil layer (a sound due to contact between the screw point 7b and soil, sand, gravel, or the like) is generated. ) Is propagated through the rod portion 7 a to reach the loading table 4, detected by the sound detection means 13, and sent to the soil determination unit 15.
[0016]
As shown in FIG. 2, the soil determination unit 15 obtains the above-described penetration amount, Nsw value, and load value for the output signal (hereinafter referred to as acoustic data) group SD of the sound detection means 13. All the acoustic data in (n is an arbitrary positive number, the same applies hereinafter) is sampled. Then, as shown in the lower part of FIG. 2, a histogram represented by the square value of the size f (x) (x is an arbitrary positive number) of each acoustic data and the number of data is generated. Further, in this histogram, an area A (n) of a region exceeding a preset threshold is obtained, and the soil quality in the section is sandy soil according to the ratio of the area A (n) to the total area of the histogram. Or whether it is cohesive soil. In general, sandy soil produces a louder sound than cohesive soil, so that the area of the region exceeding the threshold value T in the aforementioned histogram increases. That is, when the ratio of the total area of the area exceeding the threshold T in the histogram is larger than the boundary value (for example, 10% or more), it is determined as sandy soil, and when it is small (for example, less than 10%) In the case of ()), it is determined that the soil is viscous.
[0017]
When the soil quality is determined as described above, a coefficient corresponding to the result is read from the storage unit 22 into the arithmetic processing unit 16. The calculation processing unit 16 also reads the corresponding load and the number of half revolutions Nsw per meter, calculates a converted N value using the above formula 1, and stores the result in the storage unit 22. In this manner, the converted N value is sequentially obtained and stored in the storage unit 22 as the penetration test proceeds. Therefore, it is not necessary to obtain the converted N value from the obtained test data after the penetration test is completed, and the burden on the operator after the penetration test can be reduced.
[0018]
In the above description, the example of determining the soil coefficient used for the calculation of the converted N value according to the soil has been introduced. However, the technical idea of the present invention is that other data used for the calculation according to the soil is used. The present invention can also be applied to a case where selection is necessary, and is not limited to the above example. In addition, regarding the soil determination processing method by the soil determination unit 15, the sound described in Japanese Patent Application No. 2001-322492 previously proposed is adopted for the acoustic data preprocessing, so that the sound for soil determination can be obtained. The data will be more accurate.
[0019]
【The invention's effect】
The present invention relates to a sound detection means for detecting a sound propagated through the penetrating rod, a soil quality determination section for determining soil quality based on acoustic data detected by the sound detection means, and a soil quality determined by the soil quality determination section. And an arithmetic processing unit that selectively acquires data necessary for arithmetic processing and performs predetermined arithmetic processing. For this reason, it is possible to obtain sound data with high precision and high accuracy by the sound detection means without being affected by ambient noise, operator skill level, condition, and the like. Then, it is possible to determine the soil quality from the acoustic data, select data corresponding to the soil quality determination result, and obtain an accurate calculation processing result. In particular, in the calculation process of the converted N value, there is an effect that it is possible to calculate a correct converted N value and determine an accurate ground hardness. In addition, since the processing conventionally performed after the penetration test by the worker is automated, there is an advantage that the burden on the worker after the test can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view of a penetration testing machine according to the present invention.
FIG. 2 is an explanatory diagram illustrating an example of a histogram generated in a soil determination unit.
FIG. 3 is a front view of a conventional penetration testing machine.
FIG. 4 is an enlarged partially cutaway cross-sectional view of a main part of a conventional penetration testing machine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Penetration testing machine 2 Weight 3 Support | pillar 4 Loading platform 5 Chuck 7 Penetration rod 7a Rod part 7b Screw point 8 Chain member 9 Sprocket 11 Powder brake 13 Sound detection means 14 Control unit 15 Soil judgment part 16 Calculation processing part

Claims (3)

A penetrating member that is loaded with a predetermined load and is rotated as necessary to penetrate into the ground;
Sound detecting means capable of detecting sound transmitted through the penetrating member as the penetrating member penetrates into the ground;
A soil determination unit that generates a histogram from acoustic data of a predetermined section detected by the sound detection unit , applies a preset threshold value to the histogram, and determines the soil quality of the section according to the area of the area exceeding the threshold. When,
An arithmetic processing unit that obtains a soil coefficient necessary for calculation of the converted N value prepared in advance according to the soil determined by the soil determination unit, and performs processing of calculating the converted N value using the soil coefficient . Penetration testing machine characterized by that. The calculation processing unit calculates a soil coefficient Asw corresponding to the load value Wsw and a soil coefficient Bsw corresponding to the half rotation number Nsw of the penetrating member per 1 m at the time of the rotation penetration according to the soil determined by the soil determination unit. Acquired,
Conversion N value = Asw · Wsw + Bsw · Nsw
2. The penetration tester according to claim 1, wherein the converted N value is calculated by the following. When the penetrating member penetrates into the ground, the sound transmitted through the penetrating member is detected by the sound detecting means, and a histogram is generated from the acoustic data of a predetermined section detected by the sound detecting means, and the histogram is preset. Applying the threshold value, the soil quality of the section is determined according to the area of the area exceeding the threshold value, and a soil coefficient necessary for calculating the converted N value is acquired by the arithmetic processing unit according to the determination result, and the converted N value A method for automatically calculating a converted N value, characterized in that

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