Waste dump instability type and off-site influence range evaluation method

Abstract

The invention relates to a waste dump instability type and off-site influence range evaluation method, which comprises two steps of instability movement distance calculation and instability off-site maximum influence range evaluation, and is characterized in that the instability type comprises two disaster types of slag surface rolling stone and slag body landslide, and the slag surface rolling stone disaster comprises a first type of rolling stone movement and a second type of rolling stone movement; the slag landslide disaster comprises a first type of landslide movement and a second type of landslide movement. The influence of waste dump instability on surrounding facilities is elaborated, the relation between the horizontal distance and the vertical height difference between the surrounding facilities and the adjacent slope face on the side where the surrounding facilities are located is mainly considered, and the potential instability influence range needs to be combined for common determination. The influence range can be considered as a datum point of the safety protection distance, and the safety protection distance between facilities with different importance degrees and the dumping site can be determined by performing coefficient increase on the datum point.

Description

Technical Field

[0001] The invention relates to the fields of engineering construction and disaster prevention, and in particular to a method for evaluating the instability type of a spoil dump and the off-site impact range. Background Art

[0002] A large number of spoil dumps have been formed in the process of urban and rural development, mining, enterprise factories, water conservancy roads and other infrastructure construction. Safety accidents such as spoil dump instability and landslides occur from time to time. Therefore, for projects with spoil dump facilities, some areas need to conduct spoil dump instability impact assessments during the initial site selection and later acceptance stages of the project, mainly to evaluate the types of disasters and impact ranges caused by the failure of interception and drainage measures and support engineering in the spoil dump.

[0003] At present, there are no industry standards or relevant specifications for the evaluation of the instability of spoil dumps. Due to different implementation requirements and intensities in different places, the evaluation methods and contents vary greatly, and it is difficult to unify the evaluation and assessment standards. For example, other existing industry specifications uniformly define the safety protection distance between the spoil dump and the downstream facilities as 1H~2H (H is the maximum height of the spoil dump pile); the instability area is not considered; the starting calculation position is not considered; the off-site impact distance is not analyzed; the slopes on both sides and the rear edge of the spoil dump are not considered, which is unreasonable, as follows:

[0004] (1) For most spoil dumps, the dump is filled in a platform-by-platform manner. When the platform is wide enough, the spoil dump cannot slide as a whole, but slides on one or more platforms. At this time, it is obviously unreasonable to use 1 to 2 times the maximum slag height as the safety protection distance. Instead, it should be determined comprehensively based on the potential instability type, instability generation area, starting calculation position, movement distance and amplification factor.

[0005] (2) During the dumping process, not only the front edge will form a slope, but there may also be slope surfaces on both sides and the rear edge. In this case, the characteristics of each slope, potential instability type, instability movement distance and off-site impact range should be calculated and analyzed separately.

[0006] (3) Without considering the overall appearance and stability of the spoil dump, the spoil dump can only have an impact on the off-site environment when it becomes unstable and moves outside the site. Therefore, it is necessary to calculate the off-site impact range of the spoil dump's instability.

[0007] (4) The impact of the instability of the spoil dump on the surrounding facilities (including downstream) is mainly determined by considering the relationship between the horizontal distance and vertical height difference between the hazardous object and the slope (slope surface) on which it is located, combined with the potential instability impact range. Summary of the invention

[0008] The purpose of the present invention is to provide a method for evaluating the instability type and off-site impact range of a spoil dump to solve the problems raised in the background technology. The formation mechanism, movement characteristics, movement distance, off-site impact range and safety protection distance of two disaster types, namely, spoil dump slag landslide and slag surface rolling, are calculated and analyzed to complete the evaluation method described in the present invention.

[0009] To achieve the above purpose, the present invention is divided into two steps: calculation of unstable movement distance and evaluation of the maximum off-site impact range of slag surface rolling and slag body landslide:

[0010] Step 1: The instability types include two disaster types: slag surface rolling and slag body landslide:

[0011] The slag surface rock rolling disaster includes: first-class rock rolling movement and second-class rock rolling movement;

[0012] The first type of stone rolling is completed within the venue and has no direct impact on the external environment of the venue;

[0013] The second type of stone rolling movement has an impact on the external environment of the venue, and the distance between the stone rolling movement and the boundary of the venue when it stops is considered as its off-site impact range;

[0014] The second type of rolling stone movement is to analyze the impact of landslide instability in the spoil dump by calculating the ground rolling distance. The calculation method adopts the potential energy-kinetic energy conversion theory. The specific calculation formula is as follows:

[0015] v=v0+at

[0016]

[0017] Where:

[0018] v is the speed of the rolling stone on the slope;

[0019] v0 is the initial speed of the rolling stone at the top of the slope, which is 0m / s;

[0020] a is the rolling stone acceleration, unit: m / s 2 ;

[0021] m is the mass of the rolling stone, unit: kg;

[0022] u1 is the rolling friction coefficient of the slag slope, or the energy loss coefficient of the slag slope rolling;

[0023] α is the slope angle of the rolling surface of the slope;

[0024] L is the slope length, unit: m;

[0025] When the stone rolls to the foot of the slope, it begins to decelerate with an initial velocity of V due to the weakening of gravitational potential energy. The calculation formula is as follows:

[0026]

[0027] Where:

[0028] S is the horizontal movement distance of the rolling stone, unit: m;

[0029] a2 is the acceleration of the horizontal motion of the rolling stone, unit: m / s 2 ;

[0030] t is the horizontal motion time of the rolling stone, unit: s;

[0031] m is the mass of the rolling stone, unit: kg;

[0032] u2 is the rolling friction coefficient of the natural slope;

[0033] mg is the gravity on the rolling stone;

[0034] The slag landslide disaster includes: first-class landslide movement and second-class landslide movement;

[0035] The first type of landslide movement is completed within the site and has no direct impact on the external environment of the site;

[0036] The second type of landslide movement affects the external environment of the site, and the distance between the outermost side of the landslide accumulation body and the site boundary is regarded as its off-site impact range;

[0037] The engineering analogy method is used to calculate the sliding distance of the landslide caused by the instability of the slag body. The specific formula is:

[0038]

[0039] Where: L—is the impact range of landslide caused by slag (m);

[0040] H—maximum vertical height of potential sliding surface (m);

[0041] α—friction angle inside the slag body, unit: degree;

[0042] φ—is the terrain slope, unit: degree;

[0043] Step 2: The maximum impact range outside the instability field is divided into 4 categories:

[0044] S2-1. For the first type of rockfall and landslide, since their movements are completed within the site and have no direct impact on the external environment of the site, it can be considered that they have no off-site impact range.

[0045] S2-2. For the second type of stone rolling motion, the distance between the stone rolling motion and the boundary of the venue when it stops is regarded as its off-site impact range, denoted as Lg.

[0046] S2-3. Similarly, for the first type of landslide movement, it can be considered that there is no off-site impact range. For the second type of landslide movement, the distance between the outermost side of the landslide accumulation body and the site boundary is regarded as its off-site impact range, recorded as Lh.

[0047] S2-4. For each slope surface of the spoil dump, the maximum off-site impact range is the maximum value of the off-site impact range of rockfall and landslides generated by the slope surface, such as the formula: Lmax=max(Lg, Lh).

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] 1. According to the characteristics of spoil dump, the instability direction and the scope of off-site impact are analyzed, and the concept of slope surface of spoil dump is proposed.

[0050] 2. The four movement forms of rocks on the slag surface of the spoil dump are explained, including sliding, free falling, bouncing collision and rolling, and their main movement laws are summarized.

[0051] 3. The characteristics of slag surface rolling movement were analyzed, and the first and second types of rolling movement were defined: the first type of rolling movement is completed within the site, which will have a certain impact on the integrity, aesthetics and local stability of the spoil dump, but will not have a direct impact on the external environment of the site. The second type of rolling movement has exceeded the scope of the spoil dump and may have an impact on the external environment of the site.

[0052] 4. Use the potential energy-kinetic energy conversion theory to calculate the movement distance of the slag surface rolling stone.

[0053] 5. The sliding mechanism of slag landslide was analyzed: the fill soil is prone to local soil collapse during the natural settlement and consolidation process, which may further develop into local slag landslide. There is also a phenomenon that there is no local collapse or collapse before the overall sliding of the slag.

[0054] 6. The sliding starting position (distance starting position) is determined: the sliding starting position is not necessarily the outermost part of the slag pile, but the potential sliding shear outlet position.

[0055] 7. Define the first and second types of landslides: The first type of landslides are completed within the site, which will have a certain impact on the integrity, aesthetics and stability of the spoil dump, but will not have a direct impact on the external environment of the site. The second type of landslides have exceeded the scope of the spoil dump and may have an impact on the external environment of the site.

[0056] 8. Use the engineering analogy method to calculate the sliding distance of the landslide caused by the instability of the spoil dump.

[0057] 9. Define the off-site impact range of slag surface rolling and slag body landslide: For the first type of rolling and landslide movement, since their movement is completed within the site and has no direct impact on the external environment of the site, it can be considered that there is no off-site impact range. For the second type of rolling, the distance from the site boundary when the rolling stops is regarded as its off-site impact range. Similarly, for the second type of landslide movement, the distance from the outermost side of the landslide accumulation body to the site boundary is regarded as its off-site impact range.

[0058] 10. The maximum off-site impact range of each slope surface of the spoil dump was analyzed.

[0059] 11. In general, the harm of the instability of the spoil dump to the surrounding facilities (including downstream) mainly considers the relationship between the horizontal distance and vertical height difference between the surrounding facilities and the side slope (slope surface) on which they are located, and needs to be determined in combination with the potential instability impact range. This impact range can be considered as the reference point for the safety protection distance, and the safety avoidance distance between facilities of different importance and the spoil dump can be determined by increasing the coefficient based on this reference point. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 Schematic diagram of the slopes facing the spoil dump in all directions and the impact range outside the site.

[0061] Figure 2 Schematic diagram of slag surface rolling movement and off-site impact range;

[0062] Figure 3 Schematic diagram of the starting position of slag sliding and the off-site impact range; DETAILED DESCRIPTION

[0063] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] Usually, after the slag is piled up, multiple slopes will be formed, that is, the height of the slag pile in multiple directions is greater than the current ground height, forming a slope surface. At this time, the impact of the spoil dump is also multi-directional, and because the height of the slope surface in each direction is different, the impact range is also different, such as Figure 1 As shown, the specific situation is:

[0065] (1) For a gully-type spoil dump, the maximum impact range caused by the disaster is usually located in the downstream valley, because the slope height of the spoil dump is the highest there. Assuming the slope height is 1-1' and the impact range outside the field is 1-1", when an object in the valley (such as House 1) is within the impact range of 1-1", it is determined that the object is at risk of being instable by the spoil dump.

[0066] (2) When the object (such as house 1') is located on both sides of the gully downstream of the dump, it is necessary to consider both the horizontal distance and vertical height difference between the object and the gully, analyze the impact of slag instability on the accumulation of the downstream gully and the burial of both sides, and comprehensively consider the harm to the objects on both sides.

[0067] (3) When the objects (such as House 2 and House 3) are located on the periphery of the site (such as the ground on the east side) and the current ground elevation is lower than the slag surface elevation, it is also necessary to consider the impact of the houses on the landslide caused by the instability of the slag. Assuming that the maximum height of the slope on the east side of the spoil dump is 2-2', the off-site impact range is 2-2", and the main affected object is House 2; the off-site impact range of the slope is 3-3', and the main affected object is House 3.

[0068] (4) When the object (such as House 4) is located around the spoil dump (such as the west side of the ground) and the current ground elevation is greater than the slag surface elevation, there is no slope surface in this direction of the slag dump, so there is no need to consider the hazard of slag instability.

[0069] (5) When the object is located upstream of the spoil dump, when the current ground elevation is less than the slag surface elevation, there is a slope surface, and the hazard of slag dump instability also needs to be considered; when the current ground elevation is greater than the slag surface elevation, there is no slope surface in this direction of the surface slag dump, so there is no need to consider the hazard of slag instability.

[0070] The method for evaluating the instability type and off-site impact range of a spoil dump disclosed in the present invention includes two steps: calculating the instability movement distance and evaluating the maximum off-site impact range of the instability; the instability type includes two disaster types: slag surface rolling stone and slag body landslide:

[0071] S1. Calculation of unstable motion distance:

[0072] S1-1. Stone rolling disaster on slag surface

[0073] 1.1 Slag surface rolling stone movement mechanism

[0074] Generally, there are four main forms of movement of slag surface blocks, namely ① sliding, ② free fall, ③ bouncing and collision, and ④ rolling, among which: sliding is the overall movement mode of a large-scale homogeneous body; free fall is usually formed on steep slopes or cliffs with a large slope and nearly vertical; bouncing and collision are usually aimed at situations with a certain slope and a large hardness of the rock mass on the slope; rolling is the rolling movement of a hard, nearly round object from top to bottom on the slope.

[0075] Since the dumping site is mostly filled in a sloped and platform-based manner, the main movement mode of the larger rock mass on the slag surface is rolling. Figure 2 This is an ideal slag surface rolling stone motion analysis model, assuming the following conditions:

[0076] ①: Assume the slag pile height is H;

[0077] ②: There are two levels of slope from bottom to top, namely the first slope and the second slope;

[0078] ③: The first level slope has a height of h1, a slope of α1, a slope length of L1, and a platform width of L1'; the second level slope has a height of h2, a slope of α2, a slope length of L2, and a platform width of L2';

[0079] ④: The stones on the slope are approximately circular, and they move down the slope in a rolling manner.

[0080] At this time, the movement characteristics of the slag surface rolling stone are:

[0081] (1) Assuming that the speed of the stone drops to zero (v'=0) when it rolls from O0 along L2 to O0' on the L1' platform, the kinetic energy of the stone converted from the potential energy h2 is completely eliminated. The stone rolling movement is completed within the scope of the venue and will not have a direct impact on the external environment of the venue. This is defined as the first type of stone rolling movement.

[0082] (2) Assuming that the rock on the L2' platform does not stop when it rolls down to the L1' platform and continues to roll down along the slope L1 (v'≠0), or the rock on the L1' platform rolls down the slope L1 to O1' under the disturbance, and O1' is located outside the site, the movement of the rock is completed both within the site and outside the site, which may have a direct impact on the external environment of the site, and it is defined as the second type of rock rolling movement. When v'=0, the rolling height of the rock is h1.

[0083] (3) For the second type of rock rolling motion, when the motion stops at point O1' outside the site, the distance Lg between point O1' and the boundary of the spoil dump is the off-site impact range of the motion.

[0084] 1.2 The impact range of slag rolling stone movement outside the site

[0085] The first type of stone rolling is completed within the site, which will have a certain impact on the integrity, aesthetics and local stability of the spoil dump, but will not have a direct impact on the external environment of the site.

[0086] The second type of stone rolling movement has exceeded the scope of the spoil dump and may have an impact on the external environment of the site.

[0087] Therefore, when the platform width of a certain slope in the venue is large and can completely consume the potential energy of the rock rolling movement within the upper slope and the slope above it, the rock rolling movement within this slope and the slope above it can be ignored, that is, it can be classified as the first type of rock rolling movement. At this time, only the rock rolling movement below this slope needs to be considered, and the distance S needs to be calculated to analyze the impact of the rock rolling on various elements within the distance S.

[0088] The calculation method of rock fall adopts the potential energy-kinetic energy conversion theory as follows:

[0089] ① Assuming that the rolling stone accelerates from a certain point at a speed of v0 = 0m / s, according to the force analysis of the rolling stone, for a fill slope with a slope of α, the speed of the rolling stone rolling from the top of the slope to the slope is calculated as follows:

[0090] v=v0+at

[0091]

[0092] Where:

[0093] v is the speed of the rolling stone on the slope;

[0094] v0 is the initial speed of the rolling stone at the top of the slope, which is 0m / s;

[0095] a is the acceleration of the rolling stone (m / s 2 );

[0096] m is the mass of the rolling stone (kg).

[0097] u1 is the rolling friction coefficient of the slag slope, which is approximately the energy loss coefficient of the slag rolling down the slope.

[0098] α is the slope angle of the rolling surface of the slope;

[0099] L is the length of the slope (m).

[0100] Considering that the valley downstream of the abandoned site is not horizontal but has a certain potential energy, the base friction coefficient is appropriately adjusted.

[0101] ② When the stone rolls to the foot of the slope, it begins to decelerate with an initial velocity of V due to the weakening of its gravitational potential energy. The calculation formula is as follows:

[0102]

[0103] Where:

[0104] S is the horizontal movement distance of the rolling stone (m);

[0105] a2 is the acceleration of the rolling stone in horizontal motion (m / s 2 );

[0106] t is the horizontal motion time of the rolling stone (s);

[0107] m is the mass of the rolling stone (kg);

[0108] u2 is the rolling friction coefficient of the natural slope.

[0109] According to the above formula, the speed of the rolling stone when it falls to the foot of the slope can be calculated first, and then the horizontal rolling distance S of the rolling stone can be further calculated. When the rolling stone moves to the outside of the spoil dump, the distance between the stopping position of the rolling stone and the boundary of the site is the impact range outside the rolling stone field, recorded as Lg.

[0110] S1-2. Slag landslide disaster

[0111] 2.1 Movement mechanism of slag landslide

[0112] According to the instability characteristics and development law of slag, it can be divided into two modes: slag collapse and slag landslide. Slag collapse mainly occurs in loose fill slope sections, because the filling process fails to strictly layer rolling and compaction, and the fill compaction coefficient is not controlled. When effective support measures are not taken at the foot or slope surface, the fill is prone to local soil collapse during natural settlement and consolidation. After the collapse, the upper soil forms a large-angle air surface, which further causes a larger collapse and forms a collapse.

[0113] When the slag body collapses, the local instability of the slag body may further develop into a slag landslide, which is basically a traction landslide. In addition, there is also a phenomenon of no local collapse or collapse before the overall sliding of the slag body.

[0114] 2.2 Determination of sliding starting position (distance starting position)

[0115] The sliding start position is not necessarily the outermost part of the slag pile, but the potential shear exit position of the sliding body, such as Figure 3 shown.

[0116] (1) Case 1: The height difference between platform 1 and the existing ground (ground 1) is large and forms a slope surface 1. At this time, platform 1 and slope surface 1 may together form a potential sliding surface 1, that is, the slag may slide along the sliding surface 1 (not necessarily the most unfavorable sliding surface). At this time, the shear outlet 1 of the sliding surface needs to be used as the starting position of the slag instability.

[0117] (2) Case 2: When the height difference between platform 2 and the existing ground (ground 2) is small, the horizontal soil pressure is small, and platform 2 cannot become a potential sliding surface. Platform 2' and slope surface 2 may together form a potential sliding surface 2. At this time, shear outlet 2 cannot become a potential shear outlet, but shear outlet 2' may become a potential shear outlet. In this case, shear outlet 2' needs to be used as the starting position of slag instability.

[0118] When the slag landslide deposits are completely located within the site, the slag landslide is completed within the site and will not have a direct impact on the outside of the site, which is defined as the first type of landslide movement. When the slag landslide deposits are completely located outside the site, the slag landslide is completed both within the site and outside the site, which may have a direct impact on the outside of the site, which is defined as the second type of landslide movement.

[0119] 2.3 Sliding distance of slag landslide and off-site impact range

[0120] The first type of landslide movement is completed within the site, which will have a certain impact on the integrity, aesthetics and stability of the spoil dump, but will not have a direct impact on the external environment of the site.

[0121] The second type of landslide movement has exceeded the scope of the spoil dump and may have an impact on the external environment of the site.

[0122] The engineering analogy method is used to calculate the sliding distance of the landslide caused by the instability of the slag body. The specific formula is:

[0123]

[0124] Where: L—is the impact range of landslide caused by slag (m);

[0125] H—maximum vertical height of potential sliding surface (m);

[0126] α—friction angle inside the slag body (°);

[0127] φ—topographic slope (°);

[0128] Similarly, the distance between the outermost side of the landslide accumulation body and the site boundary is taken as the off-site impact range of the landslide, denoted as Lh.

[0129] S2. Maximum impact range of slag surface rolling and slag landslide outside the site

[0130] (1) For the first type of rockfall and landslide, since their movements are completed within the site and have no direct impact on the external environment of the site, it can be considered that they do not have an off-site impact range.

[0131] (2) For the second type of rock rolling motion, the distance between the rock rolling and the boundary of the field when it stops is regarded as its off-field impact range, denoted as Lg.

[0132] (3) Similarly, for the first type of landslide movement, it can be considered that there is no off-site influence range. For the second type of landslide movement, the distance between the outermost side of the landslide accumulation body and the site boundary is regarded as its off-site influence range, denoted as Lh.

[0133] (4) For each slope surface of the spoil dump, the maximum off-site impact range is the maximum value of the off-site impact range of rockfall and landslides generated by the slope surface, as follows:

[0134] Lmax=max(Lg, Lh).

Claims

1. A method for evaluating the instability type of a spoil dump and its off-site impact range, characterized by: The evaluation method consists of two steps: calculation of unstable motion distance and evaluation of the maximum impact range outside the unstable field. Step 1: Instability types include two types of disasters: slag surface rolling and slag landslide: The slag surface rock rolling disaster includes: first-class rock rolling movement and second-class rock rolling movement; The first type of stone rolling is completed within the venue and has no direct impact on the external environment of the venue; The second type of stone rolling movement has an impact on the external environment of the venue, and the distance between the stone rolling movement and the boundary of the venue when it stops is considered as its off-site impact range; The second type of rolling stone movement is to analyze the impact of landslide instability in the spoil dump by calculating the ground rolling distance S. The calculation method adopts the potential energy-kinetic energy conversion theory. The specific calculation formula is as follows: ； Where: v is the speed of the rolling stone on the slope; v0 is the initial speed of the rolling stone at the top of the slope, which is 0m / s; a is the rolling stone acceleration, unit: m / s 2 ; m is the mass of the rolling stone, unit: kg; u1 is the rolling friction coefficient of the slag slope, or the energy loss coefficient of the slag slope rolling; α is the slope angle of the rolling surface of the slope; L is the slope length, unit: m; When the stone rolls to the foot of the slope, it begins to decelerate with an initial velocity of V due to the weakening of gravitational potential energy. The calculation formula is as follows: ； Where: S is the horizontal movement distance of the rolling stone, unit: m; a2 is the acceleration of the horizontal motion of the rolling stone, unit: m / s 2 ; t is the horizontal motion time of the rolling stone, unit: s; m is the mass of the rolling stone, unit: kg; u2 is the rolling friction coefficient of the natural slope; mg is the gravity on the rolling stone; The slag landslide disaster includes: first-class landslide movement and second-class landslide movement; The first type of landslide movement is completed within the site and has no direct impact on the external environment of the site; The second type of landslide movement affects the external environment of the site, and the distance between the outermost side of the landslide accumulation body and the site boundary is regarded as its off-site impact range; The engineering analogy method is used to calculate the sliding distance of the landslide caused by the instability of the slag body. The specific formula is: ； Where: L—is the impact range of landslide caused by slag, unit: m; H—maximum vertical height of potential sliding surface, unit: m; α—friction angle inside the slag body, unit: degree; φ—is the terrain slope, unit: degree; Step 2: The maximum impact range outside the instability field is divided into 4 categories: S2-1. For the first type of rockfall and landslide, since their movements are completed within the site and have no direct impact on the external environment of the site, it can be considered that they do not have an off-site impact range; S2-2, for the second type of rock rolling, the distance between the rock rolling and the boundary of the field when it stops is regarded as its off-field impact range, recorded as Lg; S2-3. Similarly, for the first type of landslide movement, it can be considered that there is no off-site influence range; for the second type of landslide movement, the distance between the outermost side of the landslide accumulation body and the site boundary is regarded as its off-site influence range, recorded as Lh; S2-4. For each slope surface of the spoil dump, the maximum off-site impact range is the maximum value of the off-site impact range of rockfall and landslides generated by the slope surface, formula: Lmax=max(Lg, Lh).

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