Methods for determining the axial direction of the underground powerhouse of a pumped storage power station and construction methods

Abstract

This invention discloses a method for determining the axial direction of an underground powerhouse in a pumped storage power station and a construction method therefor. It efficiently, accurately, and clearly displays the balance between the dominant angle θ between the powerhouse axis and the geological structural surface, and the dominant angle η between the powerhouse axis and the direction of the maximum horizontal principal stress, through an axial diagram, thus improving the efficiency of on-site surveying and application. Furthermore, it quantitatively calculates the balance point between the dominant angle θ between the powerhouse axis and the geological structural surface, and the dominant angle η between the powerhouse axis and the direction of the maximum horizontal principal stress, making the obtained powerhouse axial direction more accurate and objective.

Description

Technical Field

[0001] This invention belongs to the technical field of underground powerhouse design for pumped storage power stations, specifically relating to a method for determining the axial direction of an underground powerhouse for a pumped storage power station and a construction method therefor. Background Technology

[0002] Pumped storage power stations are an important means for the power system to solve the problem of stable power generation for residential and industrial use by filling valleys and regulating peak flows, and they are a crucial support for the development of my country's new energy industry. The underground powerhouse is one of the main structures of a pumped storage power station, and the selection of its location and axis is key to the layout of the water conveyance and power generation system, and an important part of the overall layout of the power hub, significantly impacting the project layout, construction, and investment.

[0003] The design of underground powerhouse axes needs to consider various factors, including geological structural planes, in-situ stress, surrounding rock stability, powerhouse burial depth, and the layout direction of water conveyance and power generation systems. When considering the impact of geological factors on the orientation of the powerhouse axis during the early planning stages, the industry's conventional design principle is to select an axis that intersects the geological structural plane at a large angle and the direction of the maximum horizontal principal stress at a small angle, within the large angle between the geological structural plane and the direction of the maximum horizontal principal stress. Based on this design principle, in actual construction design, structural planes or in-situ stress are usually classified into levels, and the one with a greater impact on the stability of the powerhouse or surrounding rock is taken as the primary basis for the layout of the underground powerhouse axis, while ignoring the influence of the other on the axis layout. This axis design method has become a practical experience and convention.

[0004] However, in actual engineering design, two technical challenges arise. First, both geological structural surfaces and in-situ stress affect the stability of the powerhouse. Regardless of their grade, their influence on the powerhouse's axial direction design from a geological perspective is objectively present. Ignoring either influence will cause the powerhouse's axial layout to deviate from the actual geological conditions, thus posing potential risks to the stability of the powerhouse and its surrounding rock. Second, during preliminary exploration and powerhouse axial design, the raw data obtained by technicians often shows geological structural surfaces intersecting the direction of the maximum horizontal principal stress at a small angle. In this case, the axial layout cannot simultaneously meet the aforementioned design principles. Therefore, this invention aims to provide a method for determining the axial direction of underground powerhouses in pumped storage power stations that can take into account the influence of geological structural surfaces and the maximum horizontal principal stress on the selection of the powerhouse's axial orientation, and is applicable to situations where the geological structural surfaces and the direction of the maximum horizontal principal stress intersect at a non-obtuse angle. Summary of the Invention

[0005] In response to the above-mentioned technical problems, or one of the above-mentioned technical problems, this invention proposes a method for determining the axial direction of the underground powerhouse of a pumped storage power station and a construction method therefor, so as to accurately determine the axial design direction of the underground powerhouse in different geological regions and geological environments.

[0006] This invention is implemented as follows: a method for determining the axial direction of an underground powerhouse in a pumped storage power station, comprising the following steps:

[0007] S1. Element Determination:

[0008] Develop a classification scheme for the development level of geological structural surfaces and obtain the highest development level Max(L) of the geological structural surface; measure the direction γ of the geological structural surface in the area where the plant is located and determine the development level L of the geological structural surface in the area where the plant is located.

[0009] Develop a geostress classification scheme and obtain the highest geostress level Max(T); measure the direction σ of the maximum horizontal principal stress and the numerical level T of the maximum horizontal principal stress in the area where the plant is located.

[0010] S2. Axis Diagram: Project the direction γ and development level L of the geological structure surface, the direction σ and numerical level T of the maximum horizontal principal stress of the geostress onto the azimuth map. Based on the dominant angle between the powerhouse axis and the direction of the geological structure surface, and the dominant angle between the powerhouse axis and the direction of the maximum horizontal principal stress, mark the direction ε of the first underground powerhouse axis under the influence of geological structure and geostress on the azimuth map.

[0011] Furthermore, the S2. axis diagram specifically includes the following steps:

[0012] S2.1. Azimuth Map Construction: Construct a 0-360° azimuth map. In the azimuth map, the direction angle on the circumference represents the direction of the geological structure surface and the direction of the maximum horizontal principal stress. The radius value of the circle is r = Max(Max(L), Max(T)), and the radius value of the circle r is the larger value between Max(L) and Max(T).

[0013] S2.2. Projection azimuth map: According to the direction γ of the geological structural surface and the development level L of the geological structural surface, the direction σ of the maximum horizontal principal stress and the numerical level T of the maximum horizontal principal stress, the geological structural surface and the maximum horizontal principal stress are projected onto the azimuth map respectively. Among them, the length of the geological structural surface G is r·L / Max(L), and the length of the maximum horizontal principal stress is r·T / Max(T).

[0014] S2.3. Dominant Condition Setting: Set the dominant angle between the plant axis and the geological structure surface as θ, and the dominant angle between the plant axis and the direction of the maximum horizontal principal stress as η;

[0015] S2.4. Target azimuth interval selection: Divide the azimuth map into two semicircles with the direction of the geological structural surface as the boundary. In any one of the semicircles, select a target azimuth interval where the angle between the direction of the geological structural surface and the direction of the maximum horizontal principal stress is not less than 90°.

[0016] S2.5. Marking the axis direction: On the circumference corresponding to the target orientation interval, divide the circumference interval between the maximum horizontal principal stress of the ground stress and the geological structure reconstruction surface into (T·Max(L)+L·Max(T)) equal segments; mark the direction from the maximum horizontal principal stress of the ground stress to the geological structure reconstruction surface in the T·Max(L)th equal segment; draw a ray from the center of the circle to the mark point, and the ray extends to the circumference to form an intersection point. The direction angle represented by the intersection point is the axis direction ε of the first underground powerhouse.

[0017] Furthermore, the specific setting conditions for the dominant angle between the plant axis and the geological structure surface, and between the plant axis and the direction of the maximum horizontal principal stress, are as follows: the dominant angle θ between the plant axis and the geological structure surface is 90°, and the dominant angle η between the plant axis and the direction of the maximum horizontal principal stress is 0°.

[0018] Furthermore, the geological structural surface includes fault F and fissure J; determining the direction γ of the geological structural surface in the area where the factory is located includes: calculating the direction α of fault F and the displacement D of fault F in the area where the factory is located, calculating the direction β of fissure J and the width W of fissure J, and calculating the direction γ of geological structural surface G using the formula γ=(D·α+W·β) / (D+W), wherein the values ​​of the direction α of fault F and the direction β of fissure J are both between 0-180°.

[0019] Furthermore, when multiple faults f1, f2, f3, ..., fn exist within the area where the factory is located, the direction of the faults and the fault displacement refer to the combined direction α and the combined displacement D of the multiple faults, where:

[0020] The combined direction of n faults α=(α (f1) ·D (f1) +α (f2) ·D (f2) +α (f3) ·D (f3) +…+α (fn) ·D (fn) ) / (D (f1) +D (f2) +D (f3) +…+D (fn) );

[0021] The combined fault displacement D of n faults = (D (F1) +D(F2) +D (F3) +…+D (Fn) );

[0022] Where, α (f1) α (f2) α (f3) ..., α (fn) These represent the directions of the 1st, 2nd, 3rd, ..., nth faults, respectively, using a 0-180° orientation; D (f1) D (f2) D (f3) ... D (fn) These represent the fault displacements of the 1st, 2nd, 3rd, ..., nth faults, respectively.

[0023] And / or,

[0024] When multiple cracks j1, j2, j3, ..., jn exist within the area where the factory is located, the direction β and the crack width W refer to the combined direction β and combined width W of the multiple cracks, where:

[0025] The combined direction of n cracks β=(β (j1) ·W (j1) +β (j2) ·W (j2) +β (j3) ·W (j3) +…+β (jn) ·W (jn) ) / (W (j1) +W (j2) +W (j3) +…+W (jn) );

[0026] The combined width W of n cracks = (W (j1) +W (j2) +W (j3) +…+W (jn) );

[0027] Where, β (j1) β (j2) β (j3) ..., β (jn) Let W represent the directions of the 1st, 2nd, 3rd, ..., nth fractures, respectively, using a 0-180° orientation; (J1) W (J2) W (J3) ..., W (Jn) These represent the width values ​​of the 1st, 2nd, 3rd, ..., nth cracks, respectively.

[0028] The direction of the fault and the direction of the fracture refer to the orientation of the fault and the fracture.

[0029] Furthermore, when multiple faults f1, f2, f3, ..., fn exist within the area where the factory is located, and / or when multiple fissures j1, j2, j3, ..., jn exist within the area where the factory is located, D is analyzed in descending order of their numerical values. (f1) D (f2) D (f3) ... D (fn) The fault displacement sequence is formed by sorting, and / or, W is sorted in descending order of numerical value. (J1) W (J2) W (J3) ..., W (Jn) The fracture width sequence is generated by sorting the fracture width sequence. The smaller values ​​and corresponding faults and / or fractures in the fault displacement sequence and / or fracture width sequence are removed according to a certain proportion to correct the sequence and avoid noise interference.

[0030] Furthermore, the determination of the development level L of the geological structural surface in the area where the factory is located is as follows: based on the development of the geological structural surface G and combined with regional geological survey data, the development level L of the geological structural surface in the area where the factory is located is determined according to the geological structural surface development level classification scheme; the development of the geological structural surface G includes the number of faults, the fault displacement D, the number of fractures, the fracture width W, and the attitude and distribution relationship of the faults and fractures.

[0031] The determination of the direction σ and the numerical level T of the maximum horizontal principal stress in the area where the factory is located is achieved by using the stress relief method or the hydraulic fracturing method to measure the direction and the magnitude of the maximum horizontal principal stress. Based on the magnitude of the maximum horizontal principal stress, the numerical level of the maximum horizontal principal stress in the area where the factory is located is determined according to the stress classification scheme.

[0032] Furthermore, the method used for classifying the development level of the geological structural surface is as follows:

[0033] The formula for calculating the density of geological structural surfaces is: Density of geological structural surfaces = Number of faults + (Number of fractures / 65), unit: fractures / 100m;

[0034] The classification of geological structural surface development levels is shown in the table below:

[0035] L value Development level of geological structural surfaces Density of geological structural surfaces (strips / 100m) 1 Weakly developed geological structural surfaces Geological structural surface development density <5 2 Generally developed geological structural surfaces 5≤Density of geological structural surfaces<22 3 Strongly developed geological structural surfaces Geological structural surface development density ≥22

[0036] And / or,

[0037] The aforementioned geostress classification scheme refers to the classification criteria for rock mass geostress stipulated in engineering construction standards, including the Geotechnical Engineering Investigation Specification and the Geological Investigation Specification for Hydropower Engineering.

[0038] Furthermore, it also includes:

[0039] S3. Experimental verification:

[0040] Set up physical simulation experiments or numerical simulation experiments to verify the rationality of the axial direction of the first underground powerhouse. For the axial direction of the first underground powerhouse where the experimental results show deviations, comprehensively analyze the rationality of the parameter settings and make adjustments.

[0041] And / or,

[0042] A control experiment was conducted on the existing underground powerhouse. A new underground powerhouse was constructed in accordance with the axial direction of the first underground powerhouse. By comparing the structural stability of the existing underground powerhouse and the newly built underground powerhouse, the rationality of the axial direction of the first underground powerhouse was verified. For the axial direction of the first underground powerhouse where the experimental results showed deviations, the rationality of the parameter settings was comprehensively analyzed and adjustments were made.

[0043] A construction method for an underground powerhouse of a pumped storage power station includes the following steps:

[0044] (1) Using the above-mentioned method for determining the axial direction of the underground powerhouse of the pumped storage power station, the axial direction of the underground powerhouse is determined as the axial direction of the first underground powerhouse.

[0045] (2) Based on the axial direction of the first underground powerhouse, taking into account the actual working conditions of the surrounding rock stability, the depth of the powerhouse, and the layout of the water conveyance and power generation system, the axial direction of the first underground powerhouse is adjusted to obtain the axial direction of the second underground powerhouse.

[0046] (3) Construction of the underground powerhouse shall be carried out in accordance with the axis of the second underground powerhouse.

[0047] Through the above technical solutions, the present invention can produce the following beneficial technical effects:

[0048] (1) Breaking through existing industry experience and conventions, a brand-new method for designing the axis of underground powerhouses is proposed. This method can take into account geological structural activity surfaces and geostress environments of different levels, coordinate geological structural surfaces in different directions and the maximum horizontal principal stress of geostress, so that the designed powerhouse axis direction can achieve an accurate balance between the dominant angle θ and the dominant angle η. The determination of the powerhouse axis direction is more efficient and intuitive, and more in line with the actual geological conditions and the actual geological conditions and environment during the construction of underground powerhouses. The surrounding rock stability of the underground powerhouse designed in this way is higher.

[0049] (2) By using the axis diagram method to determine the axis of the underground powerhouse, it is only necessary to obtain the original data of the grade and direction of the geological structure surface and the maximum horizontal principal stress of the ground stress. This allows for a simple, efficient and accurate determination of the theoretically most suitable and reasonable layout of the powerhouse axis under the influence of geological factors.

[0050] (3) By selecting the target azimuth interval, the azimuth map is divided into two semicircles with the direction of the geological structure surface as the boundary. In any one of the semicircles, the target azimuth interval with the angle between the direction of the geological structure surface and the direction of the maximum horizontal principal stress is not less than 90° is selected. This perfectly solves the adverse effects of the original data. In the case where the geological structure surface intersects the direction of the maximum horizontal principal stress at a small angle (acute angle) in the obtained original data, the small angle (acute angle) is cleverly converted into a large angle (obtuse angle) azimuth interval, which can enhance the applicability, application scenarios and scope of the method of the present invention.

[0051] (4) By projecting the azimuth map, the geological structural surface and the development level of the geological structural surface L, the direction of the maximum horizontal principal stress σ and the numerical level of the maximum horizontal principal stress T are projected onto the azimuth map respectively. The length of the geological structural surface G is r·L / Max(L), and the length of the maximum horizontal principal stress is r·T / Max(T). The azimuth map constructed in this way can intuitively show the overall spatial azimuth distribution of the geological structural surface and the maximum horizontal principal stress and the degree of influence on geological stability, which is convenient for geological exploration personnel to accurately and efficiently grasp the basic geomechanical conditions of the area.

[0052] (5) The balance between the dominant angle θ between the direction of the complex plant axis and the geological structure surface, and the dominant angle η between the direction of the plant axis and the direction of the maximum horizontal principal stress, is efficiently, accurately and clearly presented through the expression method of "circle-semicircle-target orientation interval", which improves the efficiency of field application. At the same time, by using the expression method of "circle-semicircle-target orientation interval", the process is progressive, avoiding the complex mathematical calculation problems and numerical interference caused by the inconsistent standards when the direction of the geological structure surface or the maximum horizontal principal stress is taken in 0-180° and 180-360°, making the selection of the direction of the geological structure surface or the maximum horizontal principal stress more flexible.

[0053] (6) Calculate the quantitative relationship between the grade and direction of the geological structure surface and the maximum horizontal principal stress in the process of determining the factory axis by quantitative means. On this basis, calculate the balance point between the dominant angle θ between the direction of the factory axis and the geological structure surface and the dominant angle η between the direction of the factory axis and the direction of the maximum horizontal principal stress by quantitative means, so that the obtained factory axis direction is more accurate and objective.

[0054] (7) Innovatively, the fault displacement and fracture width are used as weight values ​​for multiple faults and fractures to obtain the comprehensive direction of faults and fractures, as well as to obtain more accurate directional angles of geological structural surfaces including faults and fractures, providing a new method and path for geological structural direction statistics in the industry.

[0055] (8) Based on extensive geological engineering practice experience, data were compiled and summarized to form two sets of geological structural surface development level classification schemes based on the numerical attributes of faults and fissures. The geological structural surface development level classification scheme is based on the geological structural surface development density and the ratio of the sum of fault displacement and fissure width to the length of the plant along the axial direction. This provides geological technicians with a scientific quantitative basis for judging the degree of influence of faults and fissures on regional geological stability. Attached Figure Description

[0056] Figure 1 Schematic diagram of fault F-direction calculation;

[0057] Figure 2 Schematic diagram of crack J-direction calculation;

[0058] Figure 3 Schematic diagram for calculating the direction of geological structural plane G;

[0059] Figure 4 A diagram showing the projection of the orientation map;

[0060] Figure 5 A schematic diagram of the semicircle division in the orientation map;

[0061] Figure 6 Schematic diagram for determining the target location range;

[0062] Figure 7 Schematic diagram showing the segmentation of the target azimuth interval;

[0063] Figure 8 A diagram showing the axial direction ε of the first underground powerhouse. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0065] The method for determining the axial direction of the underground powerhouse of a pumped storage power station according to the present invention includes the following steps:

[0066] S1. Element Determination: Develop a geological structural surface development level classification scheme, and obtain the highest level Max(L) of geological structural surface development level according to the scheme; measure the direction γ of the geological structural surface in the area where the plant is located, and determine the development level L of the geological structural surface in the area where the plant is located. The determination of the development level L of the geological structural surface in the area where the plant is located includes: determining the development level L of the geological structural surface in the area where the plant is located according to the development status of the geological structural surface G, combined with regional geological survey data, and in accordance with the geological structural surface development level classification scheme; the development status of the geological structural surface G includes the number of faults, the fault displacement D, the number of fractures, the fracture width W, and the attitude and distribution relationship of faults and fractures.

[0067] The geological structural surface includes fault F and fracture J;

[0068] Determining the direction γ of the geological structural surface in the area where the factory is located includes: statistically analyzing the direction α and displacement D of fault F within the factory area, statistically analyzing the direction β and width W of fracture J, and calculating the direction γ of the geological structural surface G using the formula γ = (D·α + W·β) / (D + W). The values ​​of the direction α of fault F and the direction β of fracture J are both between 0 and 180°. When multiple faults f1, f2, f3, ..., fn exist within the factory area, the direction and displacement of the faults refer to the combined direction α and displacement D of the multiple faults, where: the combined direction α of the n faults = (α... (f1) ·D (f1) +α (f2) ·D (f2) +α (f3) ·D (f3) +…+α (fn) ·D (fn) ) / (D (f1) +D (f2) +D (f3) +…+D (fn) ); The combined fault displacement D of n faults = (D (F1) +D (F2) +D (F3) +…+D (Fn) ); where α (f1) α (f2) α (f3) ..., α (fn) These represent the directions of the 1st, 2nd, 3rd, ..., nth faults, respectively, using a 0-180° orientation; D (f1) D (f2) D (f3) ... D (fn) These represent the fault displacements of the 1st, 2nd, 3rd, ..., nth faults, respectively.

[0069] When multiple cracks j1, j2, j3, ..., jn exist within the area where the factory is located, the direction β and the crack width W refer to the combined direction β and combined width W of the multiple cracks, where: the combined direction β of the n cracks = (β... (j1) +β (j2) +β (j3) +…+β (jn) ) / (W (j1) +W (j2) +W (j3) +…+W (jn) The combined width W of n cracks = (W (j1) +W (j2) +W (j3) +…+W (jn) ); where β (j1) β (j2) β (j3) ..., β (jn) Let W represent the directions of the 1st, 2nd, 3rd, ..., nth fractures, respectively, using a 0-180° orientation; (J1) W (J2) W (J3) ..., W (Jn) These represent the width values ​​of the 1st, 2nd, 3rd, ..., nth fractures, respectively; the direction of the fault and the direction of the fracture refer to the orientation of the fault and the fracture.

[0070] When multiple faults f1, f2, f3, ..., fn exist within the area where the factory is located, and / or when multiple fissures j1, j2, j3, ..., jn exist within the area where the factory is located, D is analyzed in descending order of its numerical value. (f1) D (f2) D (f3) ... D (fn) The fault displacement sequence is formed by sorting, and / or, W is sorted in descending order of numerical value. (J1) W (J2) W (J3) ..., W (Jn) The fracture width sequence is generated by sorting the fracture width sequence. The smaller values ​​and corresponding faults and / or fractures in the fault displacement sequence and / or fracture width sequence are removed according to a certain proportion to correct the sequence and avoid noise interference.

[0071] Develop a geostress classification scheme and obtain the highest geostress level Max(T) based on the scheme; measure the direction σ and the numerical level T of the maximum horizontal principal stress in the area where the plant is located, including measuring the direction and magnitude of the maximum horizontal principal stress using stress relief or hydraulic fracturing methods; and determine the numerical level of the maximum horizontal principal stress in the area where the plant is located according to the geostress classification scheme based on the magnitude of the maximum horizontal principal stress.

[0072] S2. The axis diagram specifically includes the following steps:

[0073] S2.1. Azimuth Map Construction: Construct a 0-360° azimuth map. In the azimuth map, the direction angle on the circumference represents the direction of the geological structure surface and the direction of the maximum horizontal principal stress. The radius value of the circle is r = Max(Max(L), Max(T)), and the radius value of the circle r is the larger value between Max(L) and Max(T).

[0074] S2.2. Projection azimuth map: According to the direction γ of the geological structural surface and the development level L of the geological structural surface, the direction σ of the maximum horizontal principal stress and the numerical level T of the maximum horizontal principal stress, the geological structural surface and the maximum horizontal principal stress are projected onto the azimuth map respectively. Among them, the length of the geological structural surface G is r·L / Max(L), and the length of the maximum horizontal principal stress is r·T / Max(T).

[0075] S2.3. Dominant Condition Setting: Set the dominant angle between the plant axis and the geological structure surface as θ, and the dominant angle between the plant axis and the direction of the maximum horizontal principal stress as η;

[0076] S2.4. Target azimuth interval selection: Divide the azimuth map into two semicircles with the direction of the geological structural surface as the boundary. In any one of the semicircles, select a target azimuth interval where the angle between the direction of the geological structural surface and the direction of the maximum horizontal principal stress is not less than 90°.

[0077] S2.5. Marking the axis direction: On the circumference corresponding to the target orientation interval, divide the circumference interval between the maximum horizontal principal stress of the ground stress and the geological structure reconstruction surface into (T·Max(L)+L·Max(T)) equal segments; mark the direction from the maximum horizontal principal stress of the ground stress to the geological structure reconstruction surface in the T·Max(L)th equal segment; draw a ray from the center of the circle to the mark point, and the ray extends to the circumference to form an intersection point. The direction angle represented by the intersection point is the axis direction ε of the first underground powerhouse.

[0078] S3. Experimental verification:

[0079] Set up physical simulation experiments or numerical simulation experiments to verify the rationality of the axial direction of the first underground powerhouse. For the axial direction of the first underground powerhouse where the experimental results show deviations, comprehensively analyze the rationality of the parameter settings and make adjustments.

[0080] A control experiment was conducted on the existing underground powerhouse. A new underground powerhouse was constructed in accordance with the axial direction of the first underground powerhouse. By comparing the structural stability of the existing underground powerhouse and the newly built underground powerhouse, the rationality of the axial direction of the first underground powerhouse was verified. For the axial direction of the first underground powerhouse where the experimental results showed deviations, the rationality of the parameter settings was comprehensively analyzed and adjustments were made.

[0081] A construction method for an underground powerhouse of a pumped storage power station includes the following steps:

[0082] (1) Using the above-mentioned method for determining the axial direction of the underground powerhouse, the axial direction of the underground powerhouse is determined as the axial direction of the first underground powerhouse.

[0083] (2) Based on the axial direction of the first underground powerhouse, taking into account the actual working conditions of the surrounding rock stability, the depth of the powerhouse, and the layout of the water conveyance and power generation system, the axial direction of the first underground powerhouse is adjusted to obtain the axial direction of the second underground powerhouse.

[0084] (3) Construction of the underground powerhouse shall be carried out in accordance with the axis of the second underground powerhouse.

[0085] Example 1

[0086] The project involves constructing a pumped-storage power station in southeastern Heilongjiang Province. Geologically, the site is located within the Lesser Khingan Mountains-Zhangguangcai Mountains trough-fold belt (a second-order tectonic unit) of the Jilin-Heilongjiang block (a first-order tectonic unit). The proposed power plant area contains fault F, primarily consisting of three sets of faults, including two fractures with significant widths. Additionally, the area contains approximately 780 fractures with widths less than 0.01m; due to their small width, these can be neglected when calculating the overall fracture direction.

[0087] The three fault groups are as follows:

[0088] Normal fault f1, strikes approximately NW40° (direction 140°), vertical displacement is approximately 1.12m, and dip angle is approximately 58°.

[0089] The reverse fault f2 strikes approximately NE76° (76° direction), with a vertical displacement of about 0.65m and a dip angle of about 18°.

[0090] The reverse fault f3 strikes approximately NW15° (165° direction), with a vertical displacement of about 0.28 m and a dip angle of about 23.5°.

[0091] Using the formula α=(α(f1) ·D (f1) +α (f2) ·D (f2) +α (f3) ·D (f3) +…+α (fn) ·D (fn) ) / (D (f1) +D (f2) +D (f3) +…+D (fn) The calculated composite direction α of the fault system F formed by the three faults is α = (140·3.5 + 76·1.95 + 165·0.85) / (3.5 + 1.95 + 0.85) = 123.56°.

[0092] The combined fault displacement D of the three faults = (D (f1) +D (f2) +D (f3) = 2.05m;

[0093] Where, α (f1) α (f2) α (f3) D represents the directions of the 1st, 2nd, and 3rd faults, respectively. (f1) D (f2) D (f3) These represent the fault displacements of the 1st, 2nd, and 3rd faults, respectively.

[0094] See the calculation process. Figure 1 Calculation diagram of fault direction F.

[0095] The two fissures are as follows:

[0096] The two fractures, j1 and j2, have orientations of approximately NE77° and NE28°, respectively, and fracture zone widths of approximately 0.16m and 0.12m, respectively.

[0097] Using the formula β=(β (j1) ·W (j1) +β (j2) ·W (j2) +β (j3) ·W (j3) +…+β (jn) ·W (jn) ) / (W (j1) +W (j2) +W (j3) +…+W (jn) The combined direction β of multiple cracks J is calculated as β = (77·0.16 + 28·0.12) / (0.16 + 0.12) = 56°.

[0098] The overall width of the crack W = (W (j1) +W (j2) +W(j3) +…+W (jn) ) = 0.28m;

[0099] Where, β (j1) β (j2) β (j3) ..., β (jn) W represents the directions of the 1st, 2nd, 3rd, ..., nth fractures, respectively. (J1) W (J2) W (J3) ..., W (Jn) These represent the width values ​​of the 1st, 2nd, 3rd, ..., nth cracks, respectively.

[0100] See the diagram for the calculation process. Figure 2 Calculation diagram of the crack in the J direction.

[0101] It is important to note that:

[0102] Figure 1 and Figure 2 The lengths of f1, f2, f3 and j1, j2 are used only to represent relative magnitudes. The lengths of the fault F and the fracture J do not represent their absolute magnitudes or their relative magnitudes with other values ​​(f or j).

[0103] The direction of the same fault strike and the direction of geostress are usually represented in two ways: one direction in the 0-180° range and one direction in the 0-360° range, with a difference of 180° between the two methods. For the purpose of convenient and efficient calculation, this invention uniformly uses the 0-180° direction for representation and calculation.

[0104] Fault displacement and fracture zone width are obtained statistically by taking the average of multiple measurements along the fault plane and fracture surface strike direction. The fault displacement can be a horizontal stratigraphic displacement, a vertical stratigraphic displacement, or other displacements used in the industry, as long as it is suitable for the geological outcrops or geophysical exploration conditions of the area, and is accurate and easy to measure.

[0105] Based on the above statistics of the direction α of fault F and the displacement D of fault F, the direction β of fracture J and the width W of fracture in the area where the factory is located, the direction γ of the geological structural surface G is calculated using the formula γ=(D·α+W·β) / (D+W)=115.44°.

[0106] See the diagram for the calculation process. Figure 3 Calculation diagram of the direction of geological structural plane G.

[0107] It is important to note that: Figure 3The length of fault F or fracture J is used to indicate its relative magnitude to the length of fracture J or fault F. The length of geological structural surface G is neither its absolute magnitude nor its relative magnitude to other values ​​(J or F).

[0108] A scheme for classifying the development level of geological structural surfaces is formulated, that is, the development level of geological structural surfaces is classified according to industry standards or practical experience in classifying the development level of geological structural surfaces. In this embodiment, the inventors, based on industry practice and practical project experience, and on regional tectonic geological surveys and regional seismic activity records, have formulated a scheme for classifying the development level of geological structural surfaces (see Table 1-1) to determine the development level of geological structural surfaces. Because the proposed factory site is located in an area with three faults of considerable size and displacement, with displacements of 1.12m, 0.65m, and 0.28m respectively, and one of these faults having a displacement exceeding 1 meter, the combined displacement of the three faults exceeds 2 meters; there are also two large-scale fissures, both with widths exceeding 0.12m, and approximately 780 fissures with widths less than 0.01m are also present in the area; based on the above measured data, combined with regional geological survey data and geotectonic background research, and according to the geological structural surface development level classification scheme (see Table 1-1), the geological structural surface development levels are divided into: (Level 1) weakly developed geological structural surface, (Level 2) generally developed geological structural surface, (Level 3) relatively well developed geological structural surface, and (Level 4) strongly developed geological structural surface, with the highest level Max(L) = 4. According to the geological structural surface development level classification scheme, the geological structural surface development level of the area where the factory is located is determined to be Level 3, relatively well developed geological structural surface, i.e., the development level L of geological structural surface G is 3.

[0109] It should be noted that the geological structural surface development level classification scheme in Table 1-1 is only one feasible scheme. Other reasonable classification schemes in the industry can also be adopted, and all of them can be used as the scheme and basis for the geological structural surface development level classification of the factory area in this invention.

[0110] Table 1-1 Classification Scheme for the Development Level of Geological Structural Surfaces

[0111]

[0112] A geostress classification scheme is formulated, that is, the geostress classification scheme is determined based on the recommended scheme for initial geostress classification of rock mass in "Definition of High Geostress and its Qualitative and Quantitative Criteria" (see Table 2-1). The geostress level can be divided into low geostress, medium geostress and high geostress, among which the highest geostress level Max(T) = 3. The directions of the maximum horizontal principal stress in the area where the plant is located were measured using the stress relief method and the hydraulic fracturing method. They were 64° and 82° respectively (i.e., the average value of the direction of the maximum horizontal principal stress σ is 73°). The values ​​of the maximum horizontal principal stress were 13.4 MPa and 14.2 MPa respectively. Combined with the actual measured uniaxial compressive strength of the rock in the project area, it was calculated that the ground stress in the area where the plant is located belongs to the first level of the three levels of ground stress, that is, low ground stress, that is, the numerical level of the maximum horizontal principal stress σ1 is T=1 (first level ground stress corresponds to a strength-stress ratio >7. The strength-stress ratio refers to the ratio of the uniaxial compressive strength of dry rock to the measured maximum principal stress. The uniaxial compressive strength of dry rock can be measured and calculated according to existing technology. The specific calculation process of the strength-stress ratio belongs to existing technology and will not be elaborated here).

[0113] Table 2-1 Recommended schemes for initial geostress classification of rock masses

[0114]

[0115] The strength-stress ratio is defined as the ratio of the uniaxial compressive strength of dry rock to the measured maximum principal stress.

[0116] Projection azimuth map: The direction γ = 115.44° of the geological structural surface G, the development level L = 3 of the geological structural surface G, the direction σ = 73° of the maximum horizontal principal stress, and the numerical level T = 1 of the maximum horizontal principal stress are projected onto the azimuth map (L = 3, Max(L) = 4, T = 1, Max(T) = 3); the specific projection method is as follows: the radius of the circle r = Max(Max(L), Max(T)), where Max(X) represents the maximum value in the X series, that is, the radius of the circle r is the larger of Max(L) and Max(T), that is, r takes the value of 4. In the azimuth map, the length of the geological structural surface G is L·r / Max(L), that is, r·3 / 4, and the length of the maximum horizontal principal stress is T·r / Max(T), that is, r·1 / 3 (see Figure 4 ).

[0117] Advantage conditions are set as follows: In accordance with the industry's usual design principles, the plant axis intersects the geological structure surface at a large angle and intersects the direction of the maximum horizontal principal stress at a small angle. The advantageous angle between the plant axis and the direction of the geological structure surface is set to θ = 90° and the advantageous angle between the plant axis and the direction of the maximum horizontal principal stress is set to η = 0°.

[0118] Target azimuth interval selection: Divide the azimuth map into two semicircles, namely the first semicircle and the second semicircle, using the direction of the geological structural surface as the boundary (see...). Figure 5 Within any one of these semicircles (such as the first semicircle), select a target azimuth interval where the angle between the direction of the geological structural surface and the direction of the maximum horizontal principal stress is not less than 90° (see [reference]). Figure 6 ).

[0119] Determine the axis direction: On the circumference corresponding to the target azimuth interval, divide the circumference interval between the maximum horizontal principal stress and the geological structure reconstruction surface into (T·Max(L)+L·Max(T)) = 13 equal segments (see Figure 7 From the direction of the maximum horizontal principal stress towards the geological structure reconstruction surface, mark the points in the 4th equal segments (T·Max(L)). Draw rays from the center of the circle to the marks, and the rays extend to the circumference to form an intersection point. The direction angle represented by the intersection point is the axial direction ε of the first underground powerhouse (see...). Figure 8 ).

[0120] Example 2

[0121] This embodiment describes a method for determining the axial direction of an underground powerhouse in a pumped storage power station. Except for the geological structural surface development level classification scheme, which differs from that in Embodiment 1, all other steps follow the same method. In this embodiment, the inventors, drawing on extensive practical experience from previous exploration projects, developed a geological structural surface development level classification scheme based on the geological structural surface development density method (see Tables 1-2).

[0122] Table 1-2 Scheme for classifying the development level of geological structural surfaces (classifying the development level of geological structural surfaces according to their development density)

[0123]

[0124] The formula for calculating the density of geological structural surfaces is: Density of geological structural surfaces = Number of faults + (Number of fractures / 65), unit: fractures / 100m.

[0125] Example 3

[0126] This embodiment describes a method for determining the axial direction of an underground powerhouse in a pumped storage power station. Except for the geological structural surface development level classification scheme, which differs from that in Embodiment 1, all other steps follow the same method. In this embodiment, the inventors, drawing on extensive practical experience from previous exploration projects, have developed another geological structural surface development level classification scheme based on the ratio of the sum of fault displacement and fracture zone width to the length of the powerhouse along its axial direction (see Tables 1-3).

[0127] Table 1-3 Classification Scheme for Geological Structural Surface Development (Classified according to the ratio of the sum of fault displacement and fracture zone width to the length of the plant along the axial direction)

[0128]

[0129]

[0130] This invention does not make a judgment on which geological structural surface development level classification scheme is better in Examples 1, 2 and 3. As long as the geological structural surface development level classification scheme can provide a certain basis for the development level classification of geological structural surfaces, so that ordinary technicians in the industry can obtain the basis and level classification of geological structural surface development from the corresponding classification scheme, and thus be able to determine the development level of geological structural surfaces in the area where the factory project is located.

[0131] Example 4

[0132] This embodiment describes a method for determining the axial direction of an underground powerhouse in a pumped storage power station. Except for the different geostress grading scheme compared to Embodiment 1, all other steps follow the same method. In this embodiment, the geostress grading scheme is determined according to the high initial stress grading criteria in the "Code for Geotechnical Investigation" (GB50021-94) (see Table 2-2).

[0133] Table 2-2 Criteria for Classifying High Initial Stress in the "Code for Geotechnical Investigation" (GB50021-94)

[0134]

[0135] Example 5

[0136] This embodiment describes a method for determining the axial direction of the underground powerhouse of a pumped storage power station. Except for the different geostress grading scheme compared to Embodiment 1, all other steps follow the same method. In this embodiment, the geostress grading scheme is determined according to the initial geostress grading criteria for rock mass in the "Code for Geological Investigation of Hydropower Engineering" (GB50287-2016) (see Tables 2-3).

[0137] Table 2-3 Initial Geostress Grading Criteria for Rock Mass in the "Code for Geological Investigation of Hydropower Projects" (GB50287-2016)

[0138]

[0139] It should be noted that the above-mentioned geostress classification scheme is only one feasible scheme. Various other related classification schemes are commonly used in the industry and can all be used as the basis for classifying the maximum principal stress in the area where the plant is located. Currently, there is no unified standard for specific geostress classification schemes in the industry. This invention does not judge which classification scheme is superior; as long as the classification scheme can provide a certain basis for geostress classification, enabling ordinary technicians in the industry to obtain the highest level of geostress from the corresponding classification scheme and determine the geostress level of the area where the plant is located, it is sufficient. The specific methods for determining and calculating the geostress level of the area where the plant is located are existing technologies in this field and are not the purpose of this invention; therefore, this invention will not elaborate on them.

[0140] Example 6

[0141] Experimental Verification: Physical simulation experiments or numerical simulation experiments were set up to verify the rationality of the first underground powerhouse axis direction determined by the method for determining the axis direction of the underground powerhouse in the aforementioned embodiments. For the first underground powerhouse axis direction where the experimental results deviated, the rationality of the parameter settings was comprehensively analyzed and adjustments were made. A control experiment was set up for the existing underground powerhouse, and a new underground powerhouse was constructed according to the first underground powerhouse axis direction. By comparing the structural stability of the existing underground powerhouse and the newly built underground powerhouse, the rationality of the first underground powerhouse axis direction was verified. For the first underground powerhouse axis direction where the experimental results deviated, the rationality of the parameter settings was comprehensively analyzed and adjustments were made.

[0142] Example 7

[0143] A method for constructing an underground powerhouse for a pumped storage power station, characterized by the following steps:

[0144] (1) Using the method for determining the axial direction of the underground powerhouse in the aforementioned embodiment 1 or 2, the axial direction of the underground powerhouse is determined as the first axial direction of the underground powerhouse;

[0145] (2) Based on the axial direction of the first underground powerhouse, taking into account the actual working conditions of the surrounding rock stability, the depth of the powerhouse, and the layout of the water conveyance and power generation system, the axial direction of the first underground powerhouse is adjusted to obtain the axial direction of the second underground powerhouse.

[0146] (3) Construction of the underground powerhouse shall be carried out in accordance with the axis of the second underground powerhouse.

[0147] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for determining the axial direction of an underground powerhouse in a pumped storage power station, characterized in that, Includes the following steps: S1. Element Determination: Develop a classification scheme for the development level of geological structural surfaces and obtain the highest development level Max(L) of the geological structural surface; measure the direction γ of the geological structural surface in the area where the plant is located and determine the development level L of the geological structural surface in the area where the plant is located. Develop a geostress classification scheme and obtain the highest geostress level Max(T); measure the direction σ of the maximum horizontal principal stress and the numerical level T of the maximum horizontal principal stress in the area where the plant is located. S2. Axis Diagram: Project the direction γ and development grade L of the geological structural surface, and the direction σ and numerical grade T of the maximum horizontal principal stress onto the azimuth map. Based on the dominant angle between the powerhouse axis and the direction of the geological structural surface, and the dominant angle between the powerhouse axis and the direction of the maximum horizontal principal stress, mark the direction ε of the first underground powerhouse axis under the influence of geological structure and geostress on the azimuth map. This includes the following steps: S2.

1. Azimuth Map Construction: Construct a 0-360° azimuth map. In the azimuth map, the direction angle on the circumference represents the direction of the geological structure surface and the direction of the maximum horizontal principal stress. The radius value of the circle is r = Max(Max(L), Max(T)), and the radius value of the circle r is the larger value between Max(L) and Max(T). S2.

2. Projection azimuth map: According to the direction γ of the geological structural surface and the development level L of the geological structural surface, the direction σ of the maximum horizontal principal stress and the numerical level T of the maximum horizontal principal stress, the geological structural surface and the maximum horizontal principal stress are projected onto the azimuth map respectively. Among them, the length of the geological structural surface G is r·L / Max(L), and the length of the maximum horizontal principal stress is r·T / Max(T). S2.

3. Dominant Condition Setting: Set the dominant angle between the plant axis and the geological structure surface as θ, and the dominant angle between the plant axis and the direction of the maximum horizontal principal stress as η; S2.

4. Target azimuth interval selection: Divide the azimuth map into two semicircles with the direction of the geological structural surface as the boundary. In any one of the semicircles, select a target azimuth interval where the angle between the direction of the geological structural surface and the direction of the maximum horizontal principal stress is not less than 90°. S2.

5. Marking the axis direction: On the circumference corresponding to the target orientation interval, divide the circumference interval between the maximum horizontal principal stress of the ground stress and the geological structure reconstruction surface into (T·Max(L)+L·Max(T)) equal segments; mark the direction from the maximum horizontal principal stress of the ground stress to the geological structure reconstruction surface in the T·Max(L)th equal segment; draw a ray from the center of the circle to the mark point, and the ray extends to the circumference to form an intersection point. The direction angle represented by the intersection point is the axis direction ε of the first underground powerhouse.

2. The method for determining the axial direction of the underground powerhouse of a pumped storage power station according to claim 1, characterized in that, The specific conditions for setting the dominant angles between the plant axis and the geological structure surface, and between the plant axis and the direction of the maximum horizontal principal stress, are as follows: the dominant angle θ between the plant axis and the geological structure surface is 90°, and the dominant angle η between the plant axis and the direction of the maximum horizontal principal stress is 0°.

3. The method for determining the axial direction of the underground powerhouse of a pumped storage power station according to claim 1, characterized in that, The geological structural surface includes fault F and fissure J; determining the direction γ of the geological structural surface in the area where the factory is located includes: calculating the direction α of fault F and the displacement D of fault F in the area where the factory is located, calculating the direction β of fissure J and the width W of fissure J, and calculating the direction γ of geological structural surface G using the formula γ=(D·α+W·β) / (D+W), wherein the values ​​of the direction α of fault F and the direction β of fissure J are both between 0-180°.

4. The method for determining the axial direction of the underground powerhouse of a pumped storage power station according to claim 3, characterized in that, When multiple faults f1, f2, f3, ..., fn exist within the area where the factory is located, the direction and displacement of the faults refer to the combined direction α and displacement D of the multiple faults, respectively: The combined direction of n faults α=(α (f1) ·D (f1) +α (f2) ·D (f2) +α (f3) ·D (f3) +…+α (fn) ·D (fn) ) / (D (f1) +D (f2) +D (f3) +…+D (fn) ); The combined fault displacement D of n faults = (D (F1) +D (F2) +D (F3) +…+D (Fn) ); Where, α (f1) α (f2) α (f3) ..., α (fn) These represent the directions of the 1st, 2nd, 3rd, ..., nth faults, respectively, using a 0-180° orientation; D (f1) 、D (f2) 、D (f3) ... D (fn) These represent the fault displacements of the 1st, 2nd, 3rd, ..., nth faults, respectively. and / or, When multiple cracks j1, j2, j3, ..., jn exist within the area where the factory is located, the direction β and the crack width W refer to the combined direction β and combined width W of the multiple cracks, where: The combined direction of n cracks β=(β (j1) ·W (j1) +β (j2) ·W (j2) +β (j3) ·W (j3) +…+β (jn) ·W (jn) ) / (W (j1) +W (j2) +W (j3) +…+W (jn) ); The combined width W of n cracks = (W (j1) +W (j2) +W (j3) +…+W (jn) ); Where, β (j1) β (j2) β (j3) ..., β (jn) These represent the directions of the 1st, 2nd, 3rd, ..., nth fractures, respectively, using a 0-180° orientation; W (J1) W (J2) W (J3) ..., W (Jn) These represent the width values ​​of the 1st, 2nd, 3rd, ..., nth cracks, respectively. The direction of the fault and the direction of the fracture refer to the orientation of the fault and the fracture.

5. The method for determining the axial direction of the underground powerhouse of a pumped storage power station according to claim 4, characterized in that, When multiple faults f1, f2, f3, ..., fn exist within the area where the factory is located, and / or when multiple fissures j1, j2, j3, ..., jn exist within the area where the factory is located, D is analyzed in descending order of its numerical value. (f1) 、D (f2) 、D (f3) ... D (fn) The fault displacement sequence is formed by sorting, and / or, W is sorted in descending order of numerical value. (J1) W (J2) W (J3) ..., W (Jn) The fracture width sequence is generated by sorting the fracture width sequence. The smaller values ​​and corresponding faults and / or fractures in the fault displacement sequence and / or fracture width sequence are removed according to a certain proportion to correct the sequence and avoid noise interference.

6. The method for determining the axial direction of the underground powerhouse of a pumped storage power station according to claim 1, characterized in that, The development level L of the geological structure surface in the area where the factory is located is determined by: based on the development of the geological structure surface G, combined with regional geological survey data, and in accordance with the geological structure surface development level classification scheme, the development level L of the geological structure surface in the area where the factory is located is determined; the development of the geological structure surface G includes the number of faults, the fault displacement D, the number of fissures, the fissure width W, and the attitude and distribution relationship of the faults and fissures. The determination of the direction σ and the numerical level T of the maximum horizontal principal stress in the area where the factory is located is achieved by using the stress relief method or the hydraulic fracturing method to measure the direction and the magnitude of the maximum horizontal principal stress. Based on the magnitude of the maximum horizontal principal stress, the numerical level of the maximum horizontal principal stress in the area where the factory is located is determined according to the stress classification scheme.

7. The method for determining the axial direction of the underground powerhouse of a pumped storage power station according to claim 1, characterized in that, The geological structural surface development level classification scheme adopts the following method: The formula for calculating the density of geological structural surfaces is: Density of geological structural surfaces = Number of faults + (Number of fractures / 65), unit: fractures / 100m; The classification of geological structural surface development levels is shown in the table below: and / or, The aforementioned geostress classification scheme refers to the classification criteria for rock mass geostress stipulated in engineering construction standards, including the Geotechnical Engineering Investigation Specification and the Geological Investigation Specification for Hydropower Engineering.

8. The method for determining the axial direction of the underground powerhouse of a pumped storage power station according to claim 1, characterized in that, Also includes: S3. Experimental verification: Set up physical simulation experiments or numerical simulation experiments to verify the rationality of the axial direction of the first underground powerhouse. For the axial direction of the first underground powerhouse where the experimental results show deviations, comprehensively analyze the rationality of the parameter settings and make adjustments. and / or, A control experiment was conducted on the existing underground powerhouse. A new underground powerhouse was constructed in accordance with the axial direction of the first underground powerhouse. By comparing the structural stability of the existing underground powerhouse and the newly built underground powerhouse, the rationality of the axial direction of the first underground powerhouse was verified. For the axial direction of the first underground powerhouse where the experimental results showed deviations, the rationality of the parameter settings was comprehensively analyzed and adjustments were made.

9. A construction method for an underground powerhouse of a pumped storage power station, characterized in that, Includes the following steps: (1) Using the method for determining the axial direction of the underground powerhouse of the pumped storage power station as described in any one of claims 1-8, the axial direction of the underground powerhouse is determined as the first axial direction of the underground powerhouse. (2) Based on the axial direction of the first underground powerhouse, taking into account the actual working conditions of the surrounding rock stability, the depth of the powerhouse, and the layout of the water conveyance and power generation system, the axial direction of the first underground powerhouse is adjusted to obtain the axial direction of the second underground powerhouse. (3) Construction of the underground powerhouse shall be carried out in accordance with the axis of the second underground powerhouse.

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