JP6439449B2 - Exploration method of the front ground - Google Patents
Exploration method of the front ground Download PDFInfo
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- JP6439449B2 JP6439449B2 JP2015001049A JP2015001049A JP6439449B2 JP 6439449 B2 JP6439449 B2 JP 6439449B2 JP 2015001049 A JP2015001049 A JP 2015001049A JP 2015001049 A JP2015001049 A JP 2015001049A JP 6439449 B2 JP6439449 B2 JP 6439449B2
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- 238000005553 drilling Methods 0.000 claims description 40
- 238000011156 evaluation Methods 0.000 description 7
- 230000007246 mechanism Effects 0.000 description 7
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- 238000009412 basement excavation Methods 0.000 description 2
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Description
本発明は、主として山岳トンネルの切羽前方に拡がる地山の地盤性状を探査する際に適用される前方地山の探査方法に関する。 The present invention relates to a method for exploring a front ground which is applied mainly when exploring the ground properties of a natural ground spreading in front of a face of a mountain tunnel.
山岳トンネルを掘削するにあたり、切羽前方に拡がる地山の性状を適切かつ高い精度で把握することは、支保工及び補助工を含めた掘削工事全体を効率よくかつ安全に進めていく上で非常に重要である。 When excavating a mountain tunnel, grasping the nature of the natural ground spreading ahead of the face with appropriate and high accuracy is very important for efficiently and safely proceeding with the entire excavation work including supporting works and auxiliary works. is important.
トンネル切羽の前方探査を行う技術として、ドリルジャンボ（パーカッション型削孔機）やノンコア先進ボーリングマシン（ロータリー・パーカッション型削孔機）を利用したノンコア削孔による穿孔探査が知られているが、最近では、水圧ハンマを用いた穿孔探査も試みられるようになってきた（特許文献１，２）。 Drilling exploration by non-core drilling using a drill jumbo (percussion drilling machine) or non-core advanced boring machine (rotary percussion drilling machine) is known as a technology for forward exploration of tunnel face. Then, drilling exploration using a hydraulic hammer has been attempted (Patent Documents 1 and 2).
水圧ハンマは、削孔ロッドを介してボーリングマシンから伝達される給進力及び回転トルクを削孔面に作用させつつ、内蔵されたハンマピストンを高圧水で往復動させることで該削孔面に打撃力を作用させることができる先端打撃式の削孔機であって、削孔ロッドの基端側で打撃力を与えるトップハンマ式の削孔機に比べ、削孔ロッド同士の継目でエネルギーロスが生じないため、削孔可能な深度が大きく、削孔速度も大きい。 The hydraulic hammer is applied to the drilling surface by reciprocating the built-in hammer piston with high-pressure water while acting the feed force and rotational torque transmitted from the boring machine via the drilling rod on the drilling surface. Compared to top hammer type drilling machines that are capable of applying striking force and have a striking force on the base end side of the drilling rod, energy loss at the joint between the drilling rods Therefore, the depth of drilling is large and the drilling speed is high.
そのため、水圧ハンマによる前方探査が可能になれば、より遠くの地山を調査できる。 Therefore, if a forward exploration with a hydraulic hammer becomes possible, it will be possible to investigate distant ground.
水圧ハンマを用いたトンネル切羽の前方探査としては、水圧ハンマへの送水流量Ｑ及び送水圧Ｐと掘進速度Ｖから削孔エネルギーの指標値Ｅを算出し、これを給進力（フィード圧）で補正することで、切羽前方の地山における空洞部や割れ目の検出が試みられている（特許文献２）。 For the forward exploration of the tunnel face using a hydraulic hammer, the drilling energy index value E is calculated from the water supply flow rate Q, the water supply pressure P and the excavation speed V to the hydraulic hammer, and this is calculated as the feed force (feed pressure). By correcting, attempts have been made to detect cavities and cracks in the ground in front of the face (Patent Document 2).
ここで、水圧ハンマによる打撃エネルギーは、水圧と打撃数に比例すると考えることができるが、打撃数を計測することは現状では困難であるため、上記探査手法においては、打撃数に代わる指標として送水流量が用いられている。 Here, the impact energy by the hydraulic hammer can be considered to be proportional to the hydraulic pressure and the number of hits, but since it is difficult to measure the number of hits at present, in the above exploration method, water supply is used as an index instead of the hit number. Flow rate is used.
しかしながら、水圧ハンマは、ある程度の大きさの反力を削孔面から受けないと、打撃が開始されず、軟らかい地盤では、反力が得られずに打撃が行われない場合があるが、打撃が行われていないときにも、構造上、ビット先端から水が排出される。 However, if the hydraulic hammer is not subjected to a reaction force of a certain amount from the drilling surface, the hammering will not start, and in soft ground, the reaction force may not be obtained and the hammering may not be performed. Even when the operation is not performed, water is discharged from the tip of the bit due to the structure.
そのため、送水流量から打撃数を推定するには限度があり、送水流量と打撃数が比例することを前提とした上述の評価方法では判定精度が不十分で、信頼性の高い前方探査を行うことが困難であるという問題を生じていた。 Therefore, there is a limit in estimating the number of hits from the water supply flow rate, and the above-described evaluation method based on the assumption that the water supply flow rate and the number of hits are proportional has insufficient determination accuracy and performs a highly reliable forward exploration. Caused the problem of being difficult.
本発明は、上述した事情を考慮してなされたもので、水圧ハンマを用いて前方地山の地盤性状を探査する場合に信頼性を向上させることが可能な前方地山の探査方法を提供することを目的とする。 The present invention has been made in consideration of the above-described circumstances, and provides a method for exploring a forward ground that can improve reliability when exploring the ground properties of the forward ground using a hydraulic hammer. For the purpose.
上記目的を達成するため、本発明に係る前方地山の探査方法は請求項１に記載したように、ボーリングマシンに装着した削孔ロッドの先端に水圧ハンマを取り付け、該水圧ハンマで切羽等の露出面の前方に拡がる地山を削孔することにより、該前方地山の地盤性状を探査する前方地山の探査方法において、
前記水圧ハンマへの送水圧を一定時間にわたって計測して送水圧Ｐとし、
前記一定時間に対して前記水圧ハンマによる打撃が行われている時間割合βを、次式、
Ｐ＝β・Ｐ1＋（１−β）・Ｐ2 （１）
Ｐ1；打撃時の送水圧
Ｐ2；非打撃時の送水圧
から算出し、
前記βを用いて前記水圧ハンマの打撃数ｆ′を、次式、
ｆ′＝β・ｆ0・√（Ｐ1／Ｐ0） （２）
Ｐ0；基準送水圧
ｆ0；基準打撃数
から算出し、
前記水圧ハンマによる削孔エネルギーの大きさをエネルギー指標値Ｍとして定義するとともに、該エネルギー指標値を前記ｆ′を用いて、次式、
Ｍ＝Ｐ1・ｆ′／Ｖ （３）
Ｖ；削孔速度
から算出し、
前記エネルギー指標値Ｍを用いて前記前方地山の地盤性状を推定するものである。
In order to achieve the above object, a method for exploring a front ground according to the present invention is as described in claim 1, wherein a hydraulic hammer is attached to the tip of a drilling rod attached to a boring machine, In the exploration method of the front ground, which explores the ground properties of the front ground by drilling a ground that extends forward of the exposed surface,
Measure the water supply pressure to the water pressure hammer over a certain period of time to make the water supply pressure P,
A time ratio β in which the hammer is struck with respect to the predetermined time is expressed by the following equation:
P = β · P 1 + (1−β) · P 2 (1)
P 1 ： Water pressure at the time of impact
P 2 ; calculated from the water supply pressure at the time of non-blow
Using β, the number of hits f ′ of the hydraulic hammer is expressed by the following equation:
f ′ = β · f 0 · √ (P 1 / P 0 ) (2)
P 0 : Reference water pressure
f 0 ; calculated from the reference hit number,
The magnitude of the drilling energy by the hydraulic hammer is defined as an energy index value M, and the energy index value is expressed by the following formula using the f ′:
M = P 1 · f ′ / V (3)
V: calculated from the drilling speed,
The ground property of the front ground is estimated using the energy index value M.
水圧ハンマーによる打撃エネルギーを評価するにあたり、従来においては、打撃数に代えて送水流量が用いられていたところ、既に述べた通り、地山から反力が得られずに打撃が行われない場合であっても一定量の水が排出されるため、送水流量で打撃数を推定する手法では、十分な信頼性を得ることは難しい。 In evaluating the impact energy with a hydraulic hammer, the water supply flow rate was used instead of the number of hits in the past, but as already mentioned, it is not possible to hit the ground without reaction force from the ground. Even in such a case, since a certain amount of water is discharged, it is difficult to obtain sufficient reliability by the method of estimating the number of hits by the water supply flow rate.
本出願人は、脆弱部を有する地山を掘削する際、亀裂箇所で送水圧が低下する現象が頻繁に観測されるところ、かかる状況においては、上述した水圧ハンマの特性から打撃数が低下しているものと思われるため、送水圧の低下状況を調べることで打撃数を推定することができないかに着眼して研究開発を行ったところ、本願発明をなすに至ったものである。 When excavating a natural ground having a fragile part, the present applicant frequently observes a phenomenon in which the water supply pressure decreases at the crack location. In such a situation, the number of hits decreases due to the characteristics of the hydraulic hammer described above. As a result of research and development focusing on whether or not the number of hits can be estimated by examining the state of decrease in the water supply pressure, the present invention has been made.
すなわち、本発明に係る前方地山の探査方法においては、水圧ハンマで前方地山を削孔する際、まず、水圧ハンマへの送水圧を一定時間にわたって計測し、これを送水圧Ｐとする。 In other words, in the forward ground exploration method according to the present invention, when drilling the forward ground with a hydraulic hammer, first, the water supply pressure to the hydraulic hammer is measured over a certain period of time, and this is used as the water supply pressure P.
ここで、地山が良質であれば、ロッド先端に取り付けられた水圧ハンマが地山から所定の反力を受け、ロッドの基端側から供給された高圧水は、水圧ハンマの振動機構に流れて該振動機構を作動させるが、地山が例えば亀裂性であるがゆえに該地山からの反力が不足すると、高圧水は、水圧ハンマの振動機構には流れず、そのまま放水される。 Here, if the natural ground is good quality, the hydraulic hammer attached to the tip of the rod receives a predetermined reaction force from the natural ground, and the high-pressure water supplied from the base end side of the rod flows into the vibration mechanism of the hydraulic hammer. However, if the reaction force from the natural ground is insufficient because the ground is cracked, for example, the high pressure water does not flow to the vibration mechanism of the hydraulic hammer and is discharged as it is.
そのため、水圧ハンマによる打撃が行われているときは送水圧が高くなり、打撃が行われていないときは送水圧が低くなる。 For this reason, the water supply pressure increases when the water hammer is hit, and the water supply pressure decreases when the water hammer is not hit.
したがって、一定時間、例えば１秒間にわたる平均値として送水圧を計測し、その大きさが、打撃が行われているときの送水圧に近ければ、上述した一定時間中、より長い時間にわたって打撃がなされ、打撃が行われていないときの送水圧に近ければ、より短い時間しか打撃がなされなかったことがわかる。 Therefore, if the water supply pressure is measured as an average value over a certain period of time, for example, 1 second, and the magnitude is close to the water supply pressure when the batting is performed, the water is blown for a longer time during the above-mentioned certain time. If it is close to the water supply pressure when no blow is performed, it can be seen that the blow was made for a shorter time.
具体的には、打撃が行われているときの送水圧と打撃が行われていないときの送水圧を、Ｐ1、Ｐ2としてそれぞれ予め取得した上、上記一定時間において水圧ハンマによる打撃が行われている時間割合をβとし、該βを、次式、
Ｐ＝β・Ｐ1＋（１−β）・Ｐ2 （１）
Ｐ1；打撃時の送水圧
Ｐ2；非打撃時の送水圧
から求める。
Specifically, the water supply pressure when the blow is performed and the water supply pressure when the blow is not performed are acquired in advance as P 1 and P 2 , respectively, and the water hammer is blown for the predetermined time. Let β be the percentage of time that is broken,
P = β · P 1 + (1−β) · P 2 (1)
P 1 ： Water pressure at the time of impact
P 2 : Obtained from the water supply pressure when not hit.
ちなみに、Ｐ1は、高圧水が水圧ハンマの振動機構を流れる際の送水圧であるため、送水流量のほか、水圧ハンマの摩耗度に依存し、Ｐ2は、振動機構を経由せずに直接放出されるので、主として送水流量に依存するが、高圧水がいずれの流路を流れているのか把握できる状況であれば、それぞれ事前に計測しておくことが可能である。 By the way, P 1 is the water supply pressure when high-pressure water flows through the vibration mechanism of the hydraulic hammer, so it depends on the water supply flow rate and the degree of wear of the hydraulic hammer, and P 2 does not pass directly through the vibration mechanism. Since it is discharged, it depends mainly on the water flow rate, but it can be measured in advance if it is possible to grasp which flow path the high-pressure water flows through.
送水圧Ｐは、例えば０．０１秒ごとに計測された計測データを１秒間の移動平均としてデータ処理すればよい。 For the water supply pressure P, for example, the measurement data measured every 0.01 seconds may be processed as a moving average of 1 second.
ここで、上述した一定時間中、打撃が行われているときの単位時間あたりの打撃回数をｆ″とすると、単位時間あたりの打撃回数が送水圧のルートに比例することから、ｆ″は、
ｆ″：ｆ0＝√Ｐ1：√Ｐ0
となり、よって、
ｆ″＝ｆ0・√（Ｐ1／Ｐ0）
となる。
Here, if the number of hits per unit time when hitting is performed during the above-mentioned fixed time is f ″, the number of hits per unit time is proportional to the route of the water supply pressure.
f ″: f 0 = √P 1 : √P 0
And therefore
f ″ = f 0 · √ (P 1 / P 0 )
It becomes.
上述の打撃数ｆ0は、水圧ハンマ固有の諸元として製造メーカーから開示される単位時間あたりの打撃回数、送水圧Ｐ0は、同じくそのときの送水圧であり、本明細書では、便宜上、Ｐ0を基準送水圧、ｆ0を基準打撃数と呼ぶ。 The number of hits f 0 described above is the number of hits per unit time disclosed by the manufacturer as the specifications specific to the hydraulic hammer, and the water supply pressure P 0 is also the water supply pressure at that time. In this specification, for convenience, P 0 is referred to as a reference water pressure, and f 0 is referred to as a reference hit number.
したがって、上述した一定時間をｔ、一定時間中の打撃回数をＮとすると、
Ｎ＝β・ｔ・ｆ″
＝β・ｔ・ｆ0・√（Ｐ1／Ｐ0）
となり、Ｎ／ｔをｆ′とおくと、
ｆ′＝β・ｆ0・√（Ｐ1／Ｐ0） （２）
となる。
Therefore, when the above-mentioned fixed time is t and the number of hits during the fixed time is N,
N = β · t · f ″
= Β · t · f 0 · √ (P 1 / P 0 )
When N / t is set to f ′,
f ′ = β · f 0 · √ (P 1 / P 0 ) (2)
It becomes.
ｆ′は、一定時間ｔにおける打撃回数Ｎを該一定時間で除した値であって、一定時間ｔにわたるいわば平均打撃数となる。 f ′ is a value obtained by dividing the number N of hits at a fixed time t by the fixed time, and is the average number of hits over the fixed time t.
次に、水圧ハンマの１回当たりの打撃エネルギーは水圧に比例し、単位時間当たりに水圧ハンマが地山に与えた打撃エネルギーは水圧と打撃数の積に比例するので、水圧ハンマで単位長さ当たりを削孔するのに要したエネルギーを指標Ｍとすると、該Ｍは、
Ｍ＝Ｐ1・ｆ′／Ｖ （３）
Ｖ；削孔速度
となる。
Next, the impact energy per hydraulic hammer is proportional to the hydraulic pressure, and the impact energy given to the ground by the hydraulic hammer per unit time is proportional to the product of the hydraulic pressure and the number of strikes. Assuming that the energy required for drilling the hit is the index M, the M is
M = P 1 · f ′ / V (3)
V: Drilling speed.
ここで、算出された指標Ｍは、地山の堅さを表す値となるので、このエネルギー指標Ｍを用いて前方地山の地盤性状を推定する。 Here, since the calculated index M is a value representing the firmness of the natural ground, the ground property of the forward natural ground is estimated using the energy index M.
以下、本発明に係る前方地山の探査方法の実施の形態について、添付図面を参照して説明する。 DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a forward ground exploration method according to the present invention will be described below with reference to the accompanying drawings.
図１は、本実施形態に係る前方地山の探査方法の実施手順を示したフローチャート、図２は、それに用いる削孔機２０を示した側面図である。 FIG. 1 is a flowchart showing an implementation procedure of a forward ground exploration method according to the present embodiment, and FIG. 2 is a side view showing a drilling machine 20 used therefor.
削孔機２０は、ボーリングマシン２１と該ボーリングマシンに連結された削孔ロッド２３とその先端に取り付けられた水圧ハンマ２２とで構成してある。 The drilling machine 20 includes a boring machine 21, a drilling rod 23 connected to the boring machine, and a hydraulic hammer 22 attached to the tip thereof.
本実施形態に係る前方地山の探査方法においては、まず、打撃時の送水圧Ｐ1と非打撃時の送水圧Ｐ2とを予め取得する（ステップ１０１）。 In the forward ground exploration method according to the present embodiment, first, the water supply pressure P 1 at the time of impact and the water supply pressure P 2 at the time of non-attack are acquired in advance (step 101).
打撃時の送水圧Ｐ1及び非打撃時の送水圧Ｐ2は、水圧ハンマ２２が地山を実際に打撃しているのか否か、あるいは高圧水が水圧ハンマ２２の振動機構を流れているのか否かを把握できる状況で取得することが可能である。 The water pressure P 1 at the time of striking and the water pressure P 2 at the time of non-striking are whether the hydraulic hammer 22 is actually hitting a natural ground or whether high-pressure water is flowing through the vibration mechanism of the hydraulic hammer 22. It can be acquired in a situation where it can be determined whether or not.
ここで、Ｐ1は、高圧水が水圧ハンマ２２の振動機構を流れる際の送水圧であるため、送水流量Ｑのほか、水圧ハンマ２２の摩耗度に依存するのに対し、Ｐ2は、振動機構を経由せずに直接放出されるため、主として送水流量Ｑのみに依存する。 Here, P 1 is the water supply pressure when the high-pressure water flows through the vibration mechanism of the hydraulic hammer 22, and thus depends on the water supply flow rate Q and the degree of wear of the hydraulic hammer 22, while P 2 Since it is discharged directly without going through the mechanism, it depends mainly only on the water supply flow rate Q.
そのため、Ｐ1及びＰ2は、水圧ハンマ２２の使用頻度を考慮しながら、できるだけ最新の値を用いるのが望ましい。 Therefore, it is desirable to use the latest values for P 1 and P 2 as much as possible in consideration of the usage frequency of the hydraulic hammer 22.
図３は、送水流量ＱごとにＰ1及びＰ2を現地試験で取得する様子を示したグラフであり、かかるグラフを作成することで、例えば送水流量Ｑが１５０リットル／分のとき、Ｐ1を１６ＭＰａ、Ｐ2を４．５ＭＰａと定めることができる。 FIG. 3 is a graph showing how P 1 and P 2 are acquired in the field test for each water flow rate Q. By creating such a graph, for example, when the water flow rate Q is 150 liters / minute, P 1 Of 16 MPa and P 2 of 4.5 MPa.
また、削孔中の給進力Ｆが一定であるときは、水圧ハンマ２２による打撃が行われていると考えることができるので、そのときの送水圧ＰをＰ1とし、削孔中の給進力Ｆが実質的にゼロであるときは、水圧ハンマ２２による打撃が行われていないと考えることができるので、そのときの送水圧ＰをＰ2とすることも可能である。 Further, when KyuSusumuryoku F in drilling is constant, since it can be considered that the impact by the water pressure hammer 22 have been made, and the feed water pressure P at that time is P 1, feeding in drilling when Susumuryoku F is substantially zero, since it can be considered that the impact by the water pressure hammer 22 is not performed, it is also possible to feed water pressure P at that time and P 2.
なお、打撃時の送水圧Ｐ1と非打撃時の送水圧Ｐ2との事前取得は、必ずしも探査対象となる地山で行う必要はない。 In addition, the pre-acquisition of the water pressure P 1 transmission at the time of hitting the water pressure P 2 feeding of the non-blow, it is not always necessary to perform in the land mountain to be the exploration target.
次に、探査対象となる地山を水圧ハンマ２２で削孔するが、その際、水圧ハンマ２２への送水圧を一定時間ｔにわたって計測し、これを送水圧Ｐとする（ステップ１０２）。 Next, a natural mountain to be surveyed is drilled with the hydraulic hammer 22, and at that time, the water supply pressure to the hydraulic hammer 22 is measured over a predetermined time t, and this is set as the water supply pressure P (step 102).
削孔にあたっては、水圧ハンマ２２の先端における地山への押付け力が、水圧ハンマ２２の周面と地山との間に発生する周面摩擦力で変動することなく、できるだけ均一になるように、例えば１０ＭＰａに維持されるように、ボーリングマシン２１から削孔ロッド２３を介して水圧ハンマ２２に伝達される給進力Ｆを制御する。また、送水流量Ｑについても、一定の値に維持する。 In the drilling, the pressing force against the natural ground at the tip of the hydraulic hammer 22 is made as uniform as possible without being fluctuated by the peripheral frictional force generated between the peripheral surface of the hydraulic hammer 22 and the natural ground. For example, the feed force F transmitted from the boring machine 21 to the hydraulic hammer 22 through the drilling rod 23 is controlled so as to be maintained at 10 MPa. The water supply flow rate Q is also maintained at a constant value.
送水圧Ｐは、例えば０．０１秒ごとに計測された計測データをｔ秒間の移動平均としてデータ処理し、一定時間ｔは、例えば１秒間とすればよい。 For the water supply pressure P, for example, the measurement data measured every 0.01 seconds is processed as a moving average of t seconds, and the predetermined time t may be set to 1 second, for example.
このように、一定時間ｔにわたる平均値として送水圧Ｐを計測すると、水圧ハンマ２２による打撃が行われているときは送水圧が高くなり、打撃が行われていないときは送水圧が低くなるため、計測された送水圧Ｐが、打撃が行われているときの送水圧、すなわち打撃時の送水圧Ｐ1に近ければ、上述した一定時間中、より長い時間にわたって打撃がなされ、打撃が行われていないときの送水圧、すなわち非打撃時の送水圧Ｐ2に近ければ、より短い時間しか打撃がなされなかったことがわかる。 Thus, when the water supply pressure P is measured as an average value over a predetermined time t, the water supply pressure is high when the water hammer 22 is hit, and the water pressure is low when the water hammer is not hit. , measured delivery pressure P is, the closer to the feed pressure, i.e. pressure P 1 fed at impact when striking is carried out, in the given time period described above, the striking is performed over a longer time, is performed batting though not when the feed water pressure, ie, the closer of the feed water pressure P 2 during non-strike, it can be seen that only a shorter time batting has not been made.
つまり、送水圧Ｐが、送水圧Ｐ1及び送水圧Ｐ2に対して相対的にどのような大きさであるのかを知ることによって、一定期間中における打撃回数を推定することが可能であり、図３の例で言えば、例えば送水流量Ｑが１５０リットル／分のとき、計測された送水圧Ｐ（同図黒丸）の大きさが、Ｐ1（１６ＭＰａ）に近いのか、Ｐ2（４．５ＭＰａ）に近いのかを調べればよい。 That is, it is possible to estimate the number of hits during a certain period by knowing the magnitude of the water pressure P relative to the water pressure P 1 and the water pressure P 2 . In the example of FIG. 3, for example, when the water supply flow rate Q is 150 liters / minute, the measured water supply pressure P (black circle in the figure) is close to P 1 (16 MPa) or P 2 (4. What is necessary is just to investigate whether it is close to 5 MPa.
具体的には、一定時間ｔ中、水圧ハンマ２２による打撃が行われている時間割合をβとし、βを、次式、
Ｐ＝β・Ｐ1＋（１−β）・Ｐ2 （１）
又は、これを変形して、
β＝（Ｐ−Ｐ2）／（Ｐ1−Ｐ2）（１′）
から求める（ステップ１０３）。
Specifically, let β be the time ratio during which the hydraulic hammer 22 is struck for a certain time t, and β is the following equation:
P = β · P 1 + (1−β) · P 2 (1)
Or you can change this
β = (P−P 2 ) / (P 1 −P 2 ) (1 ′)
(Step 103).
次に、一定時間ｔにわたる水圧ハンマ２２の平均打撃数ｆ′を、次式、
ｆ′＝β・ｆ0・√（Ｐ1／Ｐ0） （２）
により求める（ステップ１０４）。
Next, an average hitting number f ′ of the hydraulic hammer 22 over a predetermined time t is expressed by the following equation:
f ′ = β · f 0 · √ (P 1 / P 0 ) (2)
(Step 104).
ここで、打撃数ｆ0（基準打撃数）は、水圧ハンマ２２固有の諸元として製造メーカーから開示される単位時間あたりの打撃回数、送水圧Ｐ0（基準送水圧）は、同じくそのときの送水圧である。 Here, the number of hits f 0 (reference hitting number) is the number of hits per unit time disclosed by the manufacturer as the specifications specific to the hydraulic hammer 22, and the water supply pressure P 0 (reference water supply pressure) is the same as that at that time. Water pressure.
例えば、送水圧Ｐ0が１８ＭＰａのときに打撃数ｆ0が６５Ｈｚであれば、（２）式は、
ｆ′＝β・６５・√（Ｐ1／１８） （２′）
となる。
For example, if the number of blows f 0 is 65 Hz when the water supply pressure P 0 is 18 MPa, the equation (2) is
f '= β · 65 · √ (P 1/18) (2')
It becomes.
次に、水圧ハンマ２２で単位長さ当たりを削孔するのに要したエネルギー指標Ｍを、次式、
Ｍ＝Ｐ1・ｆ′／Ｖ （３）
又は、（１）式及び（２）式を考慮して、
Ｍ＝Ｐ1・（Ｐ−Ｐ2）・ｆ0・√（Ｐ1／Ｐ0）／（Ｐ1−Ｐ2）／Ｖ （３′）
Ｖ；削孔速度
で求める（ステップ１０５）。
Next, the energy index M required for drilling per unit length with the hydraulic hammer 22 is expressed by the following equation:
M = P 1 · f ′ / V (3)
Or, considering (1) and (2),
M = P 1 · (P−P 2 ) · f 0 · √ (P 1 / P 0 ) / (P 1 −P 2 ) / V (3 ′)
V: Determined by the drilling speed (step 105).
ここで、算出されたエネルギー指標Ｍは、水圧ハンマ２２で単位長さ当たりを削孔するのに要したエネルギー、すなわち地山の堅さを表す指標となるので、このエネルギー指標Ｍを用いて前方地山の地盤性状を推定する（ステップ１０６）。 Here, the calculated energy index M is an index that represents the energy required for drilling per unit length with the hydraulic hammer 22, that is, an index representing the firmness of the natural ground. The ground property of the natural ground is estimated (step 106).
図４は、算出されたエネルギー指標Ｍを削孔深度との関係で示したグラフであり、削孔が進行して前方地山が切羽として露出したときに観測された切羽評価点を併せて示してある。 FIG. 4 is a graph showing the calculated energy index M in relation to the drilling depth, and also shows the face evaluation points observed when the drilling progresses and the front ground is exposed as a face. It is.
ここで、切羽評価点とは、圧縮強度、風化変質、割目間隔及び割目状態の４つを観察指標、湧水量と劣化を補正指標として切羽を観察し、それら項目ごとで得られた点数を所定の割合で配点してなるものであり、例えば日本道路協会の指針に定められている切羽評価点が知られている。 Here, the face evaluation score is the score obtained by observing the face using the compression strength, weathering alteration, split interval and split state as observation indicators, and the amount of spring water and deterioration as correction indicators. Is assigned at a predetermined ratio, and for example, the face evaluation score defined in the guidelines of the Japan Road Association is known.
図４でわかるように、エネルギー指標Ｍと切羽評価点とはよく整合しており、上述したエネルギー指標Ｍを用いて前方地山の地盤性状を推定可能であることがわかる。 As can be seen from FIG. 4, the energy index M and the face evaluation score are well matched, and it can be seen that the ground property of the front ground can be estimated using the energy index M described above.
以上説明したように、本実施形態に係る前方地山の探査方法によれば、一定時間ｔにわたる平均値として送水圧Ｐを計測し、該送水圧が、送水圧Ｐ1及び送水圧Ｐ2に対して相対的にどのような大きさであるのかを知ることによって、一定期間ｔ中における打撃回数、さらには単位時間当たりの打撃数を推定することが可能となり、かくして水圧ハンマ２２による前方地山の探査を従来よりも高い精度で行うことができる。 As explained above, according to the forward ground exploration method according to the present embodiment, the water supply pressure P is measured as an average value over a predetermined time t, and the water supply pressure is changed to the water supply pressure P 1 and the water supply pressure P 2 . By knowing the relative size, it is possible to estimate the number of hits during a certain period t, and further the number of hits per unit time, and thus the front ground mountain by the hydraulic hammer 22. Can be conducted with higher accuracy than before.
本実施形態では、切羽評価点を、推定すべき前方地山の地盤性状としたが、地盤性状としてどのような指標を用いるかは任意であり、例えば切羽評価点に代えて、地山等級を用いるようにしてもよい。 In this embodiment, the face evaluation score is the ground property of the front ground to be estimated, but what index is used as the ground property is arbitrary, for example, instead of the face evaluation point, the ground mountain grade is You may make it use.
かかる変形例の場合、例えば、次のように地山等級を推定することができる。 In the case of such a modification, for example, the ground level can be estimated as follows.
２１ ボーリングマシン
２２ 水圧ハンマー
２３ 削孔ロッド
21 Boring machine 22 Hydraulic hammer 23 Drilling rod
Claims (1)
前記水圧ハンマへの送水圧を一定時間にわたって計測して送水圧Ｐとし、
前記一定時間に対して前記水圧ハンマによる打撃が行われている時間割合βを、次式、
Ｐ＝β・Ｐ1＋（１−β）・Ｐ2 （１）
Ｐ1；打撃時の送水圧
Ｐ2；非打撃時の送水圧
から算出し、
前記βを用いて前記水圧ハンマの打撃数ｆ′を、次式、
ｆ′＝β・ｆ0・√（Ｐ1／Ｐ0） （２）
Ｐ0；基準送水圧
ｆ0；基準打撃数
から算出し、
前記水圧ハンマによる削孔エネルギーの大きさをエネルギー指標値Ｍとして定義するとともに、該エネルギー指標値を前記ｆ′を用いて、次式、
Ｍ＝Ｐ1・ｆ′／Ｖ （３）
Ｖ；削孔速度
から算出し、
前記エネルギー指標値Ｍを用いて前記前方地山の地盤性状を推定することを特徴とする前方地山の探査方法。 A foreground for exploring the ground properties of the front ground by attaching a hydraulic hammer to the tip of the bore rod mounted on the boring machine and drilling a ground that extends forward of the exposed surface such as a face with the hydraulic hammer. In the mountain exploration method,
Measure the water supply pressure to the water pressure hammer over a certain period of time to make the water supply pressure P,
A time ratio β in which the hammer is struck with respect to the predetermined time is expressed by the following equation:
P = β · P 1 + (1−β) · P 2 (1)
P 1 ： Water pressure at the time of impact
P 2 ; calculated from the water supply pressure at the time of non-blow
Using β, the number of hits f ′ of the hydraulic hammer is expressed by the following equation:
f ′ = β · f 0 · √ (P 1 / P 0 ) (2)
P 0 : Reference water pressure
f 0 ; calculated from the reference hit number,
The magnitude of the drilling energy by the hydraulic hammer is defined as an energy index value M, and the energy index value is expressed by the following formula using the f ′:
M = P 1 · f ′ / V (3)
V: calculated from the drilling speed,
A method for exploring a forward ground, wherein the ground property of the forward ground is estimated using the energy index value M.
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