SU1694893A1 - Method of evaluation of outburst hazard of rock mass sections - Google Patents

Abstract

The invention relates to mining and is intended to predict the degree of hazardousness of sections of a rock massif in order to ensure safe mining operations under conditions that are hazardous to rock bursts. The purpose of the invention is to increase the reliability of hazard determination in heterogeneous block arrays of hard rocks. The method includes drilling holes and measuring the velocity of longitudinal Vp and transverse Vs waves in the array using the method of multidisciplinary differential ultrasonic logging. Then, the condition of the section of the rock mass is determined by nomograms. The VP / VS interval is set within which the rock mass is in a relaxed state. Compare the current value of VP / VS with the specified and in the part of the array in which the current value of VP / VS is outside the specified limits, determine the stress state and anisotropy, based on the values of which using nomograms, determine the degree of shock. silt

Description

The invention relates to mining and is intended to predict the degree of hazardousness of sections of a rock massif in order to ensure safe mining operations under conditions that are hazardous to rock bursts.

The purpose of the invention is to increase the reliability of the determination of the impact hazard in heterogeneous block arrays of hard rock.

FIG. Figure 1 shows the graphs of the velocities of the longitudinal waves VpM of the elastic anisotropy P2 and the ratio of the velocities of the longitudinal and transverse waves (R) over the depth of the well; figure 2 - division of the area

blocks; in FIG. 3, a nomogram according to which the category of impact hazard is determined; Fig. 4 shows an example of a velocity discharge obtained by seismic profiling along an inclined borehole.

The method is carried out as follows.

In the studied area of the array, a drill of test holes or wells is drilled, along which a multidisciplinary differential ultrasound logging is performed on a constant acoustic base equal to 1.5-2.5 times the borehole diameter and the values of the velocities Vp and Vs. Then the carted interval by the value of the parameter R VP / V $

divided into two types of blocks, where R is in the range of R 1.6-2.1, where this parameter falls outside the specified interval. For the selected breed blocks, the level of their intensity is evaluated by the parameters:

Р1 - (VpMniax - Vpo) / (Vpmax - VpMmax); (1) P2 Vp ax / VpMmin, (2)

where Vpo and Vpmax are the values of the velocities of the longitudinal waves in the unloaded and extremely loaded sections of the array, determined experimentally for each type of rock;

VpMmax and VpM are the maximum and minimum velocities of longitudinal waves according to measurements in the array in two mutually orthogonal directions. Then a block is selected with maximum values of the parameters Pi and P2, the magnitude of which is the ratio of the distance from the inelastic deformation zone on the working contour to the zone with the maximum values of the parameters PI and Pa to the average diameter of the mine, judging the degree of udehoopasnost sections of the rock mass.

The category of shock hazard is found on the corresponding nomograms established empirically for each type of rock.

Thus, the proposed technical solution, by taking into account the heterogeneity of the rock massif structure and the peculiarities of determining the indicators of the stress state of the rock blocks using the method of multidisciplinary differential ultrasound logging of boreholes and boreholes, allows to increase the accuracy of determining the shock hazard of the rock massifs in conditions of heterogeneous block arrays of strong rock formations. In addition, due to the fact that it is sufficient to use bore-holes, the laboriousness of determining the impact hazard of the plots is significantly reduced, with a sufficiently reliable level of forecast accuracy for practice.

The method is carried out as follows.

The test site contains a drill of test holes or wells. The wells on the acoustic base of 1.5-2.5 diameters of the wells select profiles of maximum Vmax and minimum Vmin velocities of longitudinal elastic waves, for which circular depth longitudinal profiling is carried out at a depth of 1-3 m from the working wall with the measurement of time tp - propagation of longitudinal elastic waves and angular shift by 15-30 °. For the selected profiles, measurements are made of the propagation time of longitudinal tpmax and tpmin and transverse tsmax and tsmm elastic waves over the entire depth of the wells. From these data, calculate the change in the parameter R tpmax / tsmax and

".Mln /. min

max

R tmln / ts, as well as the change in VpMr - and VpMmln and calculate the parameters:

Pi (VpMmaX - Vpol / O / pmax - VpMmax); (one)

P2 VpMmax / VpMmln.

The parameters Vpmax and Vpo determine

0 previously in areas with maximum stress concentration, i.e. such, where the destruction of the workings and wells, and in the unloaded parts of the array (pillars, separated from

5 arrays, non-fractured zones located at depths of 30-80 m from the surface, etc.).

According to the graphs R (H), R (H) choose the blocks in which R 1.6-2.1. and blocks in which

0 R 2,1 or R 1.6 (exorbitant defective blocks, fractured zones).

By the R parameter, the array is divided into 4 blocks of the two indicated types. At the points of maximum VpM values (blocks II and IV), the param meters are determined by formulas (1) and (2)

P l 2.5 and 4.0, with known for

rocks of this field are Vpo 4.5 km / s, Vpmax 7.3 km / s. Parameter

P 2 in blocks I and IV has maximum

0 values 1.1 and P 1.15.

Then, by the established maximum values of PI, the distance from them to the zone of inelastic deformations (Np.) - Nta and the values of P2 using a nomogram

5 (FIG. 3) defines the category of impact hazard. The nomogram (Fig. 3) is established for ores of apatite deposits by means of preliminary measurements at sites with a known shock hazard category (determined by other methods) or with observable external signs of shock hazard. Thus, on the left side of the nomogram (Fig. 3), a point {Pi, Hmax} is plotted, which then, with the addition of PZ, transfers 5 seconds to the right side, where a section of the well is installed (I is the most dangerous, II is dangerous, III is safe).

Fig. 2d shows a core disking zone (hatched) for comparison, which corresponds to the selected block I according to the proposed method. The categories of production are then determined by the categories of wells: the 1st category includes combinations of neighboring wells I-I, and the 2nd category - ll-ll. HI,

5 to the 3rd - the rest.

Claims (1)

The invention The method for determining the shock hazard of rock mass areas, including drilling holes, measuring speed longitudinal Vp and transverse Vs waves in the massif using the method of multidisciplinary differential ultrasound logging and determining the state of the rock mass section by nomograms, characterized in that, in order to increase the reliability of determining the shock hazard in heterogeneous block arrays of hard rocks, the interval Vp / Vs, within which the rock mass is in an undisturbed state, compare the current value of VP / VS with the set value, and in that part of the array in which the current value of VP / VS goes beyond the specified limits, determine the stress state and anisotropy, the magnitudes of which determine the degree of impact with the use of nomograms. 7.0g ABOUT 0.5W1.5 2.0 Depth sk & Azhiny H, m Thebes 1 R2-4.0 and G %% n 0.2 о.4 о.б о.8 То / J 5 / V The ratio of Ntah / byr Parameter P2 th Ntah W "-" iVl M  P.W FIG. 2 Phie.z | „B J I 6.0 WITH) about §5С СО 5.5 f2 Depth skdaoyuiny H, m FIG. four