RU2202810C1 - Procedure of referencing and adaptation of seismic transmitters to locality - Google Patents

Abstract

FIELD: seismology. SUBSTANCE: procedure can find use for determination of coordinates of points of installation of seismic transmitters with adaptation to properties of ground in points of their installation. Range is established by propagation time of acoustic wave from blast of explosive charge in point with known coordinates to installed seismic transmitter. Procedure is based on property of constancy of speed of acoustic wave that alters insufficiently because of air temperature and humidity in contrast to speed f propagation of seismic wave that can change substantially depending on humidity, temperature and density of ground. Speed of propagation of seismic wave is found simultaneously by time of delay between seismic and acoustic waves which allows electron circuit processing seismic signals to be adapted to properties of ground in point of installation of transmitter. EFFECT: raised quality of processing of received signals. 8 dwg

Description

 The invention relates to technical means for studying the physical properties of soils and can be used to determine the coordinates of the places of installation of seismic sensors with adaptation to the properties of the soil at the place of installation of the sensor.

 Known methods of binding objects on the ground, used in surveying, topography and construction.

The first method / 1, 2 /. Forward and backward serifs (linear, angular, azimuthal). It is produced according to two landmarks (1, 2) with the previously known coordinates (X ₁ , Y ₁ ) and (X ₂ , Y ₂ ). Direct serif measurements are made from reference points, and back serifs are made from a fixed point:
- linear serifs - the distance is measured from landmarks (1, 2) to a fixed point N (with direct serif) and from point N to landmarks (with reverse) (Fig. 1);
- angular serifs (used only for direct serifs) - measured the internal angles between the directions passing through the landmarks and a fixed point N (figure 2);
- azimuthal serifs - measured directional angles of directions passing through the landmarks and a fixed point N (figure 3).

 The second method is the method of polygonometric moves (figure 4) / 2 /. It is used in the absence of landmarks within the line of sight from the installation site, relying on 1-2 starting points (landmarks). Polygonometric moves can be linear, angular azimuthal and azimuthal linear.

 The third method is combined. It is used based on one starting point (landmark) located outside the line of sight from the installation site of the object. It is carried out by constructing an azimuthal linear link.

 The fourth method is used in construction when performing working drawings, which are performed on the engineering topographic plan / 3 /. On this plan, the construction geodetic grid or the center base replacing it is applied and indicated. For housing and civil facilities, in addition, an urban geodetic grid, which should cover the entire plan. The contours of the designed buildings and structures are plotted according to the architectural and construction working drawings, taking the coordination axes of the buildings and structures combined with the inner faces of the walls. The center plan is performed with coordinate and dimensional reference. The construction geodetic grid is applied to the entire layout plan in the form of squares with sides of 10 cm. The origin is taken in the lower left corner of the sheet. Dimensioning is carried out from the center basis. The breakdown basis can be any straight line passing through two points fixed on the ground, which are denoted by the capital letters of the Russian alphabet.

 Closest to the proposed method is a method of straight linear serifs along two landmarks / 1, 2 /, which allows you to find the coordinates of an unknown point by the coordinates of two known points and the distance from these points to the desired one. In this method, two points with pre-known coordinates are selected; from these points with the help of a range finder or in steps, the distance to a point with unknown coordinates is measured; using simple formulas, make the necessary calculations to find the coordinates of the point. This method is implemented as follows (figure 5).

По формуле (2) находится расстояние между точками 1 и 2

Используя теорему косинусов, по формуле (3) находится дирекционный угол α₁

где l₁₂ - расстояние между точками 1 и 2, м;
l_1N - расстояние между точкой 1 и точкой N, м;
l_2N - расстояние между точкой 2 и точкой N, м.Two points with coordinates are defined: 1 (Y ₁ , X ₁ ) and 2 (Y ₂ , X ₂ ). From these points, the distance l _n1 and l _N2 is measured to the point N, the coordinates of which must be calculated. By the formula (1), the angle of inclination of the direction γ passing through landmarks 1 and 2 to the horizontal line of the coordinate grid Y is determined

By the formula (2) is the distance between points 1 and 2

Using the cosine theorem, the directional angle α ₁ is found by formula (3)

where l ₁₂ is the distance between points 1 and 2, m;
l _1N is the distance between point 1 and point N, m;
l _2N - distance between point 2 and point N, m.

Указанные способы имеют ряд недостатков:
- для определения расстояния на местности от точки с известными координатами до точки, координаты которой необходимо найти, необходим визуальный контакт с этой точкой;
- при необходимости найти координаты нескольких точек эта процедура занимает значительный интервал времени;
- при определении координат большой группы сейсмодатчиков, установленных дистанционным способом на местности, для создания единого сейсмического информационного поля вышеперечисленные методы неприемлемы, так как определить визуально место установки датчика невозможно.Based on the previously performed calculations, the coordinates of point N are calculated by formula (4)

These methods have several disadvantages:
- to determine the distance on the ground from a point with known coordinates to a point whose coordinates you want to find, you need visual contact with this point;
- if necessary, find the coordinates of several points, this procedure takes a significant amount of time;
- when determining the coordinates of a large group of seismic sensors installed remotely on the ground, to create a single seismic information field, the above methods are unacceptable, since it is impossible to visually determine the location of the sensor.

 The present invention solves the problem of determining the distance from a point with known coordinates to a point with unknown coordinates using a sound wave.

 For quick binding of seismic sensors to a topographic coordinate system and their adaptation to soil properties, it is advisable to use two explosive charges (100-150 g) with subsequent fixation of the arrival time of seismic and acoustic waves. The method is based on the fact of a change in the speed of sound propagation in various media depending on their density / 5 /. At the same time, the seismic receiver installed on the ground near the soil surface is affected by two components of the explosive effect: the seismic wave and the acoustic wave (Figs. 7 and 8).

The invention is illustrated by drawings, where:
- figure 6 shows a graph of the dependence of the speed of sound in air on temperature for normal atmospheric pressure 101325 Pa;
- in FIG. 7 is a diagram of the impact on the seismic receiver of acoustic and seismic waves from an explosion;
- in FIG. 8 is a view of the signal at the output of the seismic receiver from explosive action.

The fronts of seismic and acoustic waves (Fig. 8) will be shifted in time by the delay time t _ass due to the fact that the propagation velocity of the acoustic wave (≈330 m / s) is lower than the propagation velocity of the seismic wave (≈600-1400 m / s) / 5/. The propagation velocity of an acoustic wave has a weak dependence on the ambient temperature (± 10%), and the propagation velocity of a seismic wave is highly dependent on humidity and temperature / 4, 5 /. This fact is advisable to use to measure the propagation speed of a seismic wave in a particular type of soil, which allows the adaptation of the processing circuit of seismic signals by an electronic circuit.

 To determine the distances from points with known coordinates to the point of installation of the sensor (s), an acoustic wave is used, arising from the explosion of a small amount (100-150 g) of explosive. The advantages of this method are that the speed of propagation of an acoustic wave varies slightly depending on air temperature and atmospheric pressure (Fig. 6) and / 4 / and can be easily determined in contrast to the speed of a seismic wave, which has a larger attenuation coefficient and a large speed spread depending on weather conditions and soil properties / 4, 5 /.

 Implemented the proposed method as follows.

 Seismic sensors with their number and radio channel for transmitting data to the information collection and processing unit are installed on a certain site of the terrain.

 Two landmarks with pre-known coordinates are selected (fork in the road, trigonometric point, etc., or the coordinates of the installation site are determined using the satellite navigation receiver) and the air temperature is measured.

 The coordinates are entered in the data collection and processing unit, where the speed of sound for real conditions is recorded according to the schedule (Fig.6).

Simultaneously with the explosion (at point 1), a timer is activated in the data acquisition and processing unit, which counts the time interval from the moment of the explosion to the moment the signal from each seismic sensor arrives, these time intervals are stored as, for example, t _1-1 , t _1-2 , t _1-3 , ..., t _1-n depending on the number of sensors (n is the number of sensors).

In an explosion at a second point, time intervals t _2-1 , t _2-2 , t _2-3 , are fixed. .., t _2-n , which are also stored in the data acquisition and processing unit. Using the coordinates of the landmarks according to formulas (1) and (2), we find the angle of inclination of the direction γ passing through landmarks 1 and 2 to the horizontal line of the coordinate grid Y and the distance between points 1 and 2 (Fig. 5).

Using data on the speed of sound in real conditions and the obtained values of t _1-1 -t _1-n , t _2-1 -t _2-n , the distances l _1N and l _{2N are} calculated for each sensor
l _1N = t _1-N • C _sound . (5)
According to formulas (3) and (4), the coordinates of each sensor are found alternately.

где С_сейс - скорость распространения сейсмической волны, м/с;
t_зад - задержка фронта звуковой волны относительно фронта сейсмической волны (фиг.8), с.This method also allows you to calculate the speed of propagation of a seismic wave in the ground.

where C _seism is the propagation velocity of the seismic wave, m / s;
t _ass - the delay of the front of the sound wave relative to the front of the seismic wave (Fig), p.

 This allows you to determine the physical properties of the soil and adapt the equipment receiving seismic signals to improve the quality of processing of received signals.

Sources of information
1. Psarev A.A., Kovalenko A.N. Military topography. - M.: Military Publishing House, 1986, 170 p.

 2. Pasha P. S., Kornilyuk F. G. Military topography. - M.: Military Publishing House, 1952, 118 p.

 3. GOST 21.508-93. System of design documents for construction. Rules for the implementation of working documentation of master plans for enterprises, structures and civil housing facilities.

 4. Sapozhnikov M.A. Reference Acoustics. 2nd ed., Revised. and add. - M .: Radio and communications, 1989, 7 p.

 5. Gurvich I.I., Bogannik G.N. Seismic Intelligence: A Textbook for High Schools. 3rd ed., Revised. - M .: Nedra, 1980, 551 p.

Claims (1)

A seismic-acoustic method for linking and adapting seismic sensors to terrain, including a linear straight serif method, which includes determining the coordinates of an object from the coordinates of two known points and the distance from these points to the object whose coordinates you need to find, characterized in that the distance from the base points to the seismic sensor is determined by the travel time of this distance by an acoustic wave from explosions at base points with previously known coordinates, while the distance is calculated by known the value of the speed of sound propagation (C _sound ) in the medium and the time interval between the moment of the explosion and the moment of arrival of the acoustic signal to the seismic sensor (t _1-N ), at the same time using the delay time (t _ass ) between the edges of the seismic and acoustic waves calculate the value of the propagation speed seismic wave (C _seismic )

characterizing the physical properties of the soil, taking into account which they adapt the electronic circuit for processing seismic signals to the conditions of use of the seismic sensor at the installation site.

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