Excavation method by blasting

Details Excavation method by blasting Excavation method by blasting

1999-04-14

2001-04-24

Nelson, Peter A. (Department: 3641)

Ammunition and explosives

Blasting

Patterned blasting

C102S313000

Reexamination Certificate

active

06220167

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a blasting method capable of reducing ground vibration and noise generated upon blasting.
BACKGROUND ART
Conventionally, delay blasting methods using a delay detonator have been most advantageously employed to reduce ground vibration or noise effectively upon blasting. As methods for reducing ground vibration or noise more effectively, Japanese Patent Publication No. 122559/1995, Japanese Patent Application Laid-Open No. 285800/1989 and the like have proposed blasting methods using a detonator excellent in time accuracy which is controlled by integrated circuits, wherein dominant frequency or a waveform generated by a test single-hole blast is preliminarily monitored at a location where the ground vibration or noise becomes problematical and initiation intervals for a delay blast are determined based on the above-monitored dominant frequency or waveforms.
The waveforms of the ground vibration or noise generated by a blast are greatly influenced by the type of a target rock. In order to reduce ground vibration or noise generated by blasting a target rock most effectively according to the above methods, it is necessary to monitor dominant frequency or waveform of ground vibration or noise which is generated by a test single-hole blast at problematic locations every time before blasting a target rock.
Therefore, it is difficult to minimize ground vibration or noise constantly according to the conventional methods.
DISCLOSURE OF THE INVENTION
For avoiding the above drawback, the present invention provides a blasting method comprising conducting a delay blast at a particular location; predicting time series data of a waveform of ground vibration or noise at a remote location to be generated by a hypothetical single-hole blast at the particular location using at least one of previous time series data of a waveform of ground vibration or noise generated by said delay blast and actually monitored at the remote location, and the corresponding previous actually applied initiation time series of said delay blast; computing a delay blasting initiation time series for a delay blasting, which provides a waveform of ground vibration or noise satisfying specific conditions, based on the above-predicted time series data of a single-hole blast; and carrying out a subsequent delay blast according to the computed delay blasting initiation time series.
The present invention relates particularly to a blasting method comprising conducting a delay blast at the particular location; then computing the Fourier Transform of the time series data of a waveform of ground vibration or noise generated by said delay blast and actually monitored at the remote location, and the corresponding actually applied initiation time series data of said delay blast to obtain corresponding spectrums; predicting spectrums corresponding to time series data of a waveform of ground vibration or noise at a remote location to be generated by a hypothetical single-hole blast at the particular location using the corresponding spectrums obtained in the previous step; performing with the spectrums; computing the Inverse Fourier Transform of the performed spectrum; predicting time series data of a waveform of ground vibration or noise at the remote location to be generated by said hypothetical single-hole blast at the particular location; computing a delay blasting initiation time series for a delay blasting, which provides a waveform of ground vibration or noise satisfying specific conditions, based on the above-predicted time series data of a single-hole blast; and carrying out a subsequent delay blast according to the computed delay blasting initiation time series.
The present invention also relates particularly to a blasting method comprising conducting a delay blast at the particular location; then computing the cross-correlation sequence of time series data of a waveform of ground vibration or noise generated by said delay blast and actually monitored at a remote location, and the auto-correlation sequence of the corresponding actually applied initiation time series data of said delay blast; predicting time series data of a waveform of ground vibration or noise at a remote location to be generated by a hypothetical single-hole blast at the particular location, which most certainly seems to form the time series data of a waveform of ground vibration or noise of said delay blast, by solving Wiener's least squares theory according to the Levinson algorithm; computing a delay blasting initiation time series for a delay blasting, which provides a waveform of ground vibration or noise satisfying specific conditions, based on the above-predicted time series data of a single-hole blast; and carrying out a subsequent delay blast according to the computed delay blasting initiation time series.
It is possible to exemplify various methods for predicting time series data of a waveform of ground vibration or noise at a remote location, which is to be generated by a single-hole blast, using time series data of a waveform of ground vibration or noise generated by a delay blast at a particular location and the delay blasting initiation time series of said blast. The present invention may employ either a method which only uses the ground vibration or noise time series of a current delay blast, i.e,, a latest delay blast, and delay blasting initiation time series of said blast; or a method which uses the time series data of ground vibrations or noises of several previous delay blasts besides the current delay blast and delay blasting initiation time series of said previous blasts. In order to provide a clearer idea on the present invention, there will be described hereinafter several examples of the method which employs only the time series data of ground vibration or noise of a current delay blast and delay blasting initiation time series of said blast.
First of all, a successive analytical prediction method is described.
Defining the time series data of ground vibration or noise generated by a current delay blast at a particular location and a delay blasting initiation time series of the blast as a
m
and &Dgr;
i
, respectively, the time series data X
m
of ground vibration or noise generated by a single-hole blast to be predicted can be successively computed as shown below. Both a
m
and X
m
indicate an m
th
data sampled under the conditions of a sampling interval of &Dgr;
t
and a number of samples of N. Accordingly, m falls within the range of 0≦m≦N−1. &Dgr;
i
is an integer obtained by dividing i
th
delay blast initiation time T
i
with &Dgr;
t
. When the number of periods is defined as L, i falls within the range of 0≦m≦L−1. In this case, &Dgr;
0
indicates 0.
&Dgr;
0
≦t≦&Dgr;
1
, X
t
=&agr;
t
&Dgr;
1
≦t≦&Dgr;
2
, X
t
=&agr;
t
−X
(t−&Dgr;1)
&Dgr;
2
≦t≦&Dgr;
3
, X
t
=&agr;
t
−X
(t−&Dgr;2)
−X
(t−&Dgr;2)
&Dgr;
i
≦t≦&Dgr;
i+1
,
X
t
=
a
t
-
∑
n
=
1
i
⁢
X
(
t
-
Δ
⁢
 
⁢
n
)
 &Dgr;
L−1
≦t≦N
−1,
X
t
=
a
t
-
∑
n
=
1
L
-
1
⁢
X
(
t
-
Δ
⁢
 
⁢
n
)
Next, the Fourier Transform method is described.
Defining the time series data of ground vibration or noise generated at a particular location by a current delay blast as A
(t)
, delay blast time series data of the blast as &zgr;
(t)
, and time series data of ground vibration or noise of a single-hole blast to be predicted as X
(t)
, the following relationship is recognized among the three kinds of time series data.
A
(
t
)
=
∑
s
=
1
n
⁢
X
(
t
-
ts
)
·
ζ
(
ts
)
=
X
(
t
)
*
ζ
(
t
)
⁢

(
)
Namely, the waveform A
(t)
derived from a delay blast is represented by a convolution of the waveforms X
(t)
of a single-hole blast and &zgr;
(t)
, wherein t
0
=0 and X
(t)
=0 when t<0.
Supposing, for example, the amplitude of each period is the same, &zgr;
(t)
becomes 1 when an initiation timing t is t
0
, t
1
, . . . and t
n
, and

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