Method for determining axis direction of underground powerhouse of pumped storage power station and construction method

Abstract

The invention discloses a method for determining the axis direction of an underground powerhouse of a pumped storage power station and a construction method, and aims to solve the problem of balance between a dominant included angle theta between the axis of the powerhouse and the direction of a geological structure surface and a dominant included angle eta between the axis of the powerhouse and the direction of a maximum horizontal principal stress in an axis diagram mode. The information is displayed efficiently, accurately and clearly, and the field survey and application efficiency is improved; the balance point between the dominant included angle theta between the plant axis and the geologic structure plane direction and the dominant included angle eta between the plant axis and the maximum horizontal principal stress direction is calculated in a quantitative mode, so that the obtained plant axis direction is more accurate and objective.

Description

Technical Field

[0001] The invention belongs to the technical field of the design of underground powerhouse of pumped storage power station, and particularly relates to a method for determining the axis direction of the underground powerhouse of a pumped storage power station and a construction method thereof. Background Art

[0002] A pumped storage power station is an important means for the power system to solve the problems of domestic and industrial electricity consumption and stable power generation of power generation equipment through valley filling and peak shaving, and is an important support for the development of the new energy industry in China. The underground powerhouse is one of the main buildings of a pumped storage power station. The selection of its location and axis is the key to the layout of the water conveyance and power generation system, and is also an important task in the hub layout pattern, which has a significant impact on project layout, project construction, project investment, etc.

[0003] The design of the underground powerhouse axis needs to consider various factors, including geological structural planes, in-situ stresses, surrounding rock stability, powerhouse buried depth, the layout direction of the water conveyance and power generation system, etc. When considering the influence of geological factors on the design of the powerhouse axis azimuth in the early stage of the underground powerhouse axis planning, the conventional design principle in the industry is to select a powerhouse axis that intersects with the geological structural plane at a large angle and intersects with the direction of the maximum horizontal principal stress of the in-situ stress at a small angle between the large angle between the geological structural plane and the maximum horizontal principal stress of the in-situ stress. Based on the above design principle, in actual construction design, the structural plane or the in-situ stress is usually classified by grade, and the one with a greater impact on the stability of the powerhouse or the surrounding rock between the structural plane and the in-situ stress is taken as the main control basis for the layout of the underground powerhouse axis, while ignoring the influence of the other on the layout of the powerhouse axis. This axis design method has even become practical experience and convention.

[0004] However, in the actual engineering design process, two technical problems are faced. One is that both the geological structural plane and the in-situ stress affect the stability of the powerhouse. Regardless of their grades, their influence on the design of the powerhouse axis direction from a geological perspective is objectively existing. Ignoring the influence of any one of them will cause the layout of the powerhouse axis to deviate from the actual geological situation, and thus bring potential risks to the stability of the powerhouse and its surrounding rock. The other is that in the early exploration research and the process of the powerhouse axis design, the original data obtained by technical personnel often shows that the geological structural plane intersects with the direction of the maximum horizontal principal stress at a small angle. In this case, the layout of the axis direction cannot meet the requirements of the above design principle at the same time. Therefore, the present invention aims to provide a method for determining the axis direction of the underground powerhouse of a pumped storage power station that can take into account the influence degrees of the geological structural plane and the maximum horizontal principal stress on the selection of the powerhouse axis azimuth, and can be applicable to the situation where the geological structural plane and the direction of the maximum horizontal principal stress intersect at a non-obtuse angle. Summary of the Invention

[0005] In view of the above technical problems or one of the above technical problems, the present invention provides a method for determining the axis direction of an underground powerhouse of a pumped-storage power station and a construction method, so as to accurately determine the axis design direction of the underground powerhouse in different geological regions and geological environments.

[0006] The present invention is implemented as follows. A method for determining the axis direction of an underground powerhouse of a pumped-storage power station includes the following steps:

[0007] S1. Element determination:

[0008] Formulate a grading scheme for the development level of geological structural planes, and obtain the highest level Max(L) of the development level of geological structural planes; measure the direction γ of the geological structural plane in the area where the powerhouse is located, and determine the development level L of the geological structural plane in the area where the powerhouse is located;

[0009] Formulate a ground stress grading scheme, and obtain the highest level Max(T) of the ground stress level; measure the direction σ of the maximum horizontal principal stress of the ground stress in the area where the powerhouse is located and the numerical level T of the maximum horizontal principal stress of the ground stress;

[0010] S2. Axis diagramming: Project the direction γ and development level L of the geological structural plane, and the direction σ and numerical level T of the maximum horizontal principal stress of the ground stress onto an azimuth diagram respectively. According to the dominant angle between the axis of the powerhouse and the direction of the geological structural plane, and the dominant angle between the axis of the powerhouse and the direction of the maximum horizontal principal stress, mark the first axis direction ε of the underground powerhouse under the influence of geological structure and ground stress in the azimuth diagram.

[0011] Furthermore, the S2. Axis diagramming specifically includes the following steps:

[0012] S2.1. Azimuth diagram construction: Construct a 0-360° azimuth diagram. In the azimuth diagram, the direction angles on the circumference represent the direction of the geological structural plane and the direction of the maximum horizontal principal stress of the ground stress, and the radius value r of the circle = Max(Max(L), Max(T)), and the radius value r of the circle is the larger value of Max(L) and Max(T);

[0013] S2.2. Projecting the azimuth diagram: Project the geological structural plane and the maximum horizontal principal stress of the ground stress onto the azimuth diagram according to the direction γ of the geological structural plane, the development level L of the geological structural plane, the direction σ of the maximum horizontal principal stress of the ground stress, and the numerical level T of the maximum horizontal principal stress of the ground stress. Among them, the length of the geological structural plane G is r·L / Max(L), and the length of the maximum horizontal principal stress of the ground stress is r·T / Max(T);

[0014] S2.3. Dominant condition setting: Respectively set the dominant angle between the axis of the powerhouse and the direction of the geological structural plane as θ, and the dominant angle between the axis of the powerhouse and the direction of the maximum horizontal principal stress as η;

[0015] S2.4. Selection of target azimuth interval: Taking the direction of the geological structure plane as the boundary, divide the azimuth diagram into two semi - circles. In any one of the semi - circles, select the target azimuth interval where the included angle between the direction of the geological structure plane and the maximum horizontal principal stress direction of the in - situ stress is not less than 90°.

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

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

[0018] Furthermore, the geological structure plane includes a fault F and a fracture J; determining the direction γ of the geological structure plane in the area where the powerhouse is located includes: statistically analyzing the direction α and the fault throw D of the fault F in the area where the powerhouse is located, statistically analyzing the direction β and the fracture width W of the fracture J, and calculating the direction γ of the geological structure plane G using the formula γ=(D·α + W·β) / (D + W), where the values of the direction α of the fault F and the direction β of the fracture J are both within the range of 0 - 180°.

[0019] Furthermore, when there are multiple faults f1, f2, f3, …, fn in the area where the powerhouse is located, the direction and the fault throw of the faults refer to the comprehensive direction α and the comprehensive fault throw D of the multiple faults, where:

[0020] The comprehensive direction α of 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) );

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

[0022] where α (f1) 、α (f2) 、α (f3) 、…、α (fn) represent the directions of the 1st, 2nd, 3rd, …, nth faults respectively, expressed in the direction of 0 - 180°; D (f1) 、D (f2) 、D (f3) 、…、D (fn) represent the throw of the 1st, 2nd, 3rd, …, nth faults respectively;

[0023] and / or,

[0024] when there are multiple fissures j1, j2, j3, …, jn in the area where the plant is located, the direction β of the fissures and the fissure width W refer to the combined direction β of the multiple fissures and the combined width W of the multiple fissures, where:

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

[0027] where β (j1) 、β (j2) 、β (j3) 、…、β (jn) represent the directions of the 1st, 2nd, 3rd, …, nth fissures respectively, expressed in the direction of 0 - 180°; W (J1) 、W (J2) 、W (J3) 、…、W (Jn) represent the width values of the 1st, 2nd, 3rd, …, nth fissures respectively;

[0028] The direction of the fault and the direction of the fissure refer to the strike direction of the fault and the fissure.

[0029] Further, when there are multiple faults f1, f2, f3, …, fn in the area where the plant is located, and / or when there are multiple fissures j1, j2, j3, …, jn in the area where the plant is located, sort D (f1) , D (f2) , D (f3) , …, D (fn) in descending order of values to form a fault throw sequence, and / or sort W (J1) , W (J2) , W (J3) , …, W (Jn) in descending order of values to form a fissure width sequence. Eliminate the smaller values and the corresponding faults and / or fissures at the end of the sort in the fault throw sequence and / or the fissure width sequence according to a certain ratio to correct the sequence and avoid noise interference.

[0030] Further, the determination of the development level L of the geological structure plane in the area where the plant is located: According to the development of the geological structure plane G, combined with the regional geological survey data, determine the development level L of the geological structure plane in the area where the plant is located according to the geological structure plane development level division scheme; the development of the geological structure plane G includes the number of faults, the fault throw D of the faults, the number of fissures, the crack width W of the fissures, and the occurrence and distribution relationship of the faults and fissures;

[0031] The determination of the direction σ of the maximum horizontal principal stress of the in-situ stress and the numerical level T of the maximum horizontal principal stress of the in-situ stress in the area where the plant is located: Use the stress relief method or the hydraulic fracturing method to measure the direction of the maximum horizontal principal stress of the in-situ stress and the numerical value of the maximum horizontal principal stress of the in-situ stress, and determine the numerical level of the maximum horizontal principal stress of the in-situ stress in the area where the plant is located according to the in-situ stress grading scheme according to the numerical value of the maximum horizontal principal stress of the in-situ stress.

[0032] Further, the method adopted in the geological structure plane development level division scheme is as follows:

[0033] The calculation formula for the development density of the geological structure plane is: Development density of the geological structure plane = number of faults + (number of fissures / 65), unit: number / 100m;

[0034] The division of the development level of the geological structure plane is shown in the following table:

[0035] L value Development level of geological structure plane Development density of geological structure plane (number / 100m) 1 Weakly developed geological structure plane Development density of geological structure plane < 5 2 Generally developed geological structure plane 5 ≤ Development density of geological structure plane < 22 3 Strongly developed geological structure plane Development density of geological structure plane ≥ 22

[0036] and / or

[0037] The in-situ stress grading scheme refers to the grading criteria for rock mass in-situ stress stipulated in engineering construction standards including the Code for Geotechnical Engineering Investigation and the Code for Geological Investigation of Water Conservancy and Hydropower Projects.

[0038] Further, it also includes:

[0039] S3. Experimental verification:

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

[0041] and / or,

[0042] Set up a control experiment for the existing underground powerhouse, build a new underground powerhouse according to the axis direction of the first underground powerhouse, and verify the rationality of the axis direction of the first underground powerhouse by comparing the structural stability of the existing underground powerhouse and the newly built underground powerhouse. For the axis direction of the first underground powerhouse with deviations in the experimental results, comprehensively analyze the rationality of the parameter settings and make adjustments.

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

[0044] (1) Use the method for determining the axis direction of the underground powerhouse of the pumped - storage power station described above to determine the axis direction of the underground powerhouse as the axis direction of the first underground powerhouse;

[0045] (2) On the basis of the axis direction of the first underground powerhouse, comprehensively consider the actual working conditions of the surrounding rock stability, the buried depth of the powerhouse, and the layout direction of the water conveyance and power generation system, and adjust the axis direction of the first underground powerhouse to obtain the axis direction of the second underground powerhouse;

[0046] (3) Carry out the construction of the underground powerhouse according to the axis direction of the second underground powerhouse.

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

[0048] (1) Break through the existing industry experience and practices, and propose a brand - new axis design method for underground powerhouses, which can take into account geological structure surfaces and in - situ stress environments of different grades, coordinate geological structure surfaces in different directions and the maximum horizontal principal in - situ stress, so that the axis direction of the designed powerhouse can achieve an accurate balance between the dominant angle θ and the dominant angle η. The determination of the axis direction of the powerhouse is more efficient, intuitive, more in line with the actual geological conditions, and more suitable for the actual geological conditions and environment during the construction of the underground powerhouse. Therefore, the surrounding rock stability of the designed underground powerhouse is higher.

[0049] (2) Determine the axis of the underground powerhouse through the axis diagram method. Only by obtaining the grade and direction original data of the geological structure surface and the maximum horizontal principal in - situ stress, can the theoretically most suitable and reasonable layout orientation of the powerhouse axis affected by geological factors be determined simply, efficiently and accurately.

[0050] (3) By selecting the target azimuth interval, the azimuth map is divided into two semi - circles with the direction of the geological structure plane as the boundary. In any one of the semi - circles, a target azimuth interval is selected where the included angle between the direction of the geological structure plane and the direction of the maximum horizontal principal stress of the in - situ stress is not less than 90°. This perfectly solves the adverse influencing factors of the original data. In the case where the geological structure plane intersects with 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 to 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, according to the direction γ of the geological structure plane, the development level L of the geological structure plane, the direction σ of the maximum horizontal principal stress of the in - situ stress, and the numerical level T of the maximum horizontal principal stress of the in - situ stress, the geological structure plane and the maximum horizontal principal stress of the in - situ stress are respectively projected onto the azimuth map. Among them, the length of the geological structure plane G is r·L / Max(L), and the length of the maximum horizontal principal stress of the in - situ stress is r·T / Max(T). The azimuth map constructed in this way can intuitively display the overall spatial azimuth distribution of the geological structure plane and the maximum horizontal principal stress of the in - situ stress and the influence degree on geological stability, facilitating geological technical exploration personnel to accurately and efficiently master the basic situation of geomechanics in this area.

[0052] (5) The balance problem between the optimal included angle θ between the complex factory building axis and the direction of the geological structure plane and the optimal included angle η between the factory building axis and the direction of the maximum horizontal principal stress is efficiently, accurately, and clearly presented through the expression of "circle - semi - circle - target azimuth interval", improving the efficiency of on - site practical application. At the same time, using the expression of "circle - semi - circle - target azimuth interval" in a progressive manner avoids the complex mathematical calculation problems and numerical interferences caused by inconsistent standards when the direction of the geological structure plane or the maximum horizontal principal stress takes values in the ranges of 0 - 180° and 180 - 360°, making the direction of the geological structure plane or the maximum horizontal principal stress more flexible when taking values.

[0053] (6) By calculating the quantitative relationship between the grades and directions of the geological structure plane and the maximum horizontal principal stress during the determination of the factory building axis, and on this basis, calculating the balance point between the optimal included angle θ between the factory building axis and the direction of the geological structure plane and the optimal included angle η between the factory building axis and the direction of the maximum horizontal principal stress in a quantitative manner, the obtained direction of the factory building axis is more accurate and objective.

[0054] (7) Pioneeringly using the fault throw and the fracture seam width as the weight values of multiple faults and multiple fractures to obtain the comprehensive direction of the faults and the comprehensive direction of the fractures, as well as obtaining a more accurate direction angle of the geological structure plane including faults and fractures, providing a new method and path for the statistical analysis of geological structure directions in the industry.

[0055] (8) Based on a large number of geological engineering practice experiences, two sets of classification schemes for the development levels of geological structure surfaces based on the numerical attributes of faults and fissures are summarized by organizing data, that is, the classification scheme for the development levels of geological structure surfaces that classifies the development levels of geological structure surfaces according to the development density of geological structure surfaces and according to the ratio of the sum of the fault throw and the width of the fissure zone to the length of the power house along the axial direction, so that technical personnel in the geological field have a scientific quantitative judgment basis when judging the influence degree of faults and fissures on the regional geological stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 Schematic diagram for calculating the direction of fault F;

[0057] Figure 2 Schematic diagram for calculating the direction of fissure J;

[0058] Figure 3 Schematic diagram for calculating the direction of geological structure surface G;

[0059] Figure 4 Schematic diagram of azimuth map projection;

[0060] Figure 5 Schematic diagram of semi-circle division of azimuth map;

[0061] Figure 6 Schematic diagram for determining the target azimuth interval;

[0062] Figure 7 Schematic diagram of equal-segment division of target azimuth interval;

[0063] Figure 8 Diagram showing the direction ε of the axis of the first underground power house. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0064] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present 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 only used to explain the present invention and are not used to limit the present invention.

[0065] The method for determining the axis direction of the underground power house of the pumped storage power station of the present invention includes the following steps:

[0066] S1. Element determination: Develop a grading scheme for the development level of geological structure planes. Obtain the highest level Max(L) of the development level of geological structure planes according to the grading scheme for the development level of geological structure planes. Measure the direction γ of the geological structure planes in the area where the plant is located, and determine the development level L of the geological structure planes in the area where the plant is located. The determination of the development level L of the geological structure planes in the area where the plant is located includes: According to the development situation of the geological structure plane G, combined with the regional geological survey data, determine the development level L of the geological structure planes in the area where the plant is located according to the grading scheme for the development level of geological structure planes. The development situation of the geological structure plane G includes the number of faults, the fault throw D, the number of fissures, the fissure width W, and the occurrence and distribution relationship of faults and fissures.

[0067] The geological structure planes include faults F and fissures J.

[0068] The determination of the direction γ of the geological structure planes in the area where the plant is located includes: Statistically analyze the direction α of the faults F and the fault throw D in the area where the plant is located, statistically analyze the direction β of the fissures J and the fissure width W, and calculate the direction γ of the geological structure plane G using the formula γ = (D·α + W·β) / (D + W), where the values of the direction α of the faults F and the direction β of the fissures J are both between 0 - 180°. When there are multiple faults f1, f2, f3,..., fn in the area where the plant is located, the direction of the faults and the fault throw refer to the combined direction α of the multiple faults and the combined fault throw D of the multiple faults, where: The combined direction α of 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 throw D of n faults = (D (F1) +D (F2) +D (F3) +…+D (Fn) );Among them, α (f1) , α (f2) , α (f3) ,…, α (fn) respectively represent the directions of the 1st, 2nd, 3rd,…, nth faults, expressed in directions of 0 - 180°; D (f1) , D (f2) , D (f3) ,…, D (fn) respectively represent the fault throws of the 1st, 2nd, 3rd,…, nth faults;

[0069] When there are multiple cracks j1, j2, j3, ..., jn in the area where the factory building is located, the direction β of the crack and the width W of the crack refer to the comprehensive direction β of the multiple cracks and the comprehensive width W of the multiple cracks, where: the comprehensive direction β of n cracks = (β (j1) +β (j2) +β (j3) +…+β (jn) ) / (W (j1) +W (j2) +W (j3) +…+W (jn) ); The combined width of n cracks W = (W (j1) +W (j2) +W (j3) +…+W (jn) ), where β (j1) , β (j2) , β (j3) , …, β (jn) Respectively represent the directions of the 1st, 2nd, 3rd, ..., nth cracks, and are represented by the direction of 0-180°; W (J1) , W (J2) , W (J3) , …, W (Jn) They respectively represent the width values ​​of the 1st, 2nd, 3rd, ..., nth cracks; the direction of the fault and the direction of the crack refer to the strike direction of the fault and the crack.

[0070] When there are multiple faults f1, f2, f3, ..., fn in the area where the powerhouse is located, and / or when there are multiple fissures j1, j2, j3, ..., jn in the area where the powerhouse is located, D (f1) , D (f2) , D (f3) ,…,D (fn) Sort the faults into a sequence of fault throws, and / or sort the W (J1) , W (J2) , W (J3) , …, W (Jn) The crack width sequence is formed by sorting, and the smaller values ​​and corresponding faults and / or cracks in the fault distance sequence and / or crack width sequence that are ranked later are removed according to a certain ratio to correct the sequence and avoid noise interference.

[0071] Formulate the in-situ stress grading scheme, and obtain the highest level Max(T) of the in-situ stress grade according to the in-situ stress grading scheme; measure the direction σ of the maximum horizontal principal stress of the in-situ stress and the numerical grade T of the maximum horizontal principal stress of the in-situ stress in the area where the powerhouse is located, including measuring the direction of the maximum horizontal principal stress of the in-situ stress and the numerical magnitude of the maximum horizontal principal stress of the in-situ stress by using the stress relief method or the hydraulic fracturing method, and determine the numerical grade of the maximum horizontal principal stress of the in-situ stress in the area where the powerhouse is located according to the numerical magnitude of the maximum horizontal principal stress of the in-situ stress according to the in-situ stress grading scheme.

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

[0073] S2.1. Construction of the azimuth diagram: Construct a 0-360° azimuth diagram. In the azimuth diagram, the direction angles on the circumference represent the direction of the geological structure plane and the direction of the maximum horizontal principal stress of the in-situ stress. The radius value r of the circle = Max(Max(L), Max(T)), and the radius value r of the circle is the larger value of Max(L) and Max(T);

[0074] S2.2. Project the azimuth diagram: Project the geological structure plane and the maximum horizontal principal stress of the in-situ stress onto the azimuth diagram according to the direction γ of the geological structure plane, the development grade L of the geological structure plane, the direction σ of the maximum horizontal principal stress of the in-situ stress, and the numerical grade T of the maximum horizontal principal stress of the in-situ stress. Among them, the length of the geological structure plane G is r·L / Max(L), and the length of the maximum horizontal principal stress of the in-situ stress is r·T / Max(T);

[0075] S2.3. Set the advantageous conditions: Respectively set the advantageous included angle between the powerhouse axis and the direction of the geological structure plane as θ, and the advantageous included angle between the powerhouse axis and the direction of the maximum horizontal principal stress as η;

[0076] S2.4. Select the target azimuth interval: Divide the azimuth diagram into two semi-circles with the direction of the geological structure plane as the boundary. In any one of the semi-circles, select the target azimuth interval where the included angle between the direction of the geological structure plane and the direction of the maximum horizontal principal stress of the in-situ stress is not less than 90°;

[0077] S2.5. Calibrate the axis direction: On the circumference corresponding to this target azimuth interval, divide the circular arc interval between the maximum horizontal principal stress of the in-situ stress and the geological structure reconstruction plane into (T·Max(L) + L·Max(T)) equal segments; from the direction of the maximum horizontal principal stress of the in-situ stress to the geological structure reconstruction plane, mark a landmark point at the T·Max(L)th equal segment; draw a ray from the center of the circle to the landmark point, and extend the ray to the circumference to form an intersection point. The direction angle represented by the intersection point is the first underground powerhouse axis direction ε.

[0078] S3. Experimental verification:

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

[0080] Set up a control experiment for the existing underground powerhouse, construct a new underground powerhouse according to the axis direction of the first underground powerhouse, and verify the rationality of the axis direction of the first underground powerhouse by comparing the structural stability of the existing underground powerhouse and the newly built underground powerhouse. For the axis direction of the first underground powerhouse with deviations in the experimental results, comprehensively analyze the rationality of the parameter settings and make adjustments.

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

[0082] (1) Use the above method for determining the axis direction of the underground powerhouse to determine the axis direction of the underground powerhouse as the axis direction of the first underground powerhouse;

[0083] (2) On the basis of the axis direction of the first underground powerhouse, comprehensively consider the actual conditions of the surrounding rock stability, the buried depth of the powerhouse, and the layout direction of the water conveyance and power generation system, and adjust the axis direction of the first underground powerhouse to obtain the axis direction of the second underground powerhouse;

[0084] (3) Carry out the construction of the underground powerhouse according to the axis direction of the second underground powerhouse.

[0085] Embodiment 1

[0086] Undertake the pumped-storage power station project in a certain area in the southeast of Heilongjiang Province. Regionally, it is located in the Xiao Hinggan Mountains - Zhangguangcai Ridge trough fold belt (secondary tectonic unit) in the Jilin - Heilongjiang landmass (primary tectonic unit). There are mainly three groups of faults developed in the area where the powerhouse is planned to be built, and two fractures with obvious widths. In addition, there are about 780 fractures with a fracture width less than 0.01m in this area. Since the fracture width is small, it can be ignored when calculating the comprehensive direction of the fractures.

[0087] The three groups of faults are respectively:

[0088] Normal fault f1, with a strike of about NW40°, that is, direction 140°, a vertical stratigraphic throw of about 1.12m, and a fault dip of about 58°;

[0089] Reverse fault f2, with a strike of about NE76°, that is, direction 76°, a vertical stratigraphic throw of about 0.65m, and a fault dip of about 18°;

[0090] Reverse fault f3, with a strike of about NW15°, that is, direction 165°, a vertical stratigraphic throw of about 0.28m, and a fault dip 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 comprehensive direction α of the fault system F formed by the three faults is calculated as α = (140·3.5 + 76·1.95 + 165·0.85) / (3.5 + 1.95 + 0.85) = 123.56°;

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

[0093] Among them, α (f1) 、α (f2) 、α (f3) represent the directions of the 1st, 2nd, and 3rd faults respectively, and D (f1) 、D (f2) 、D (f3) represent the fault throws of the 1st, 2nd, and 3rd faults respectively.

[0094] The calculation process is shown in Figure 1 the calculation diagram of the direction of fault F.

[0095] The two fissures are respectively:

[0096] The strikes of the two fissures j1 and j2 are approximately NE77° and NE28° respectively, and the widths of the fissure zones are approximately 0.16 m and 0.12 m 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) ) to calculate the comprehensive direction β of multiple fissures J as β = (77·0.16 + 28·0.12) / (0.16 + 0.12) = 56°.

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

[0099] Among them, β (j1) , β (j2) , β (j3) , …, β (jn) respectively represent the directions of the 1st, 2nd, 3rd, …, nth fissures, and W (J1) , W (J2) , W (J3) , …, W (Jn) respectively represent the width values of the 1st, 2nd, 3rd, …, nth fissures.

[0100] The illustration of the calculation process can be seen in Figure 2 the calculation diagram of the direction of fracture J.

[0101] It should be noted that:

[0102] Figure 1 and Figure 2 are only used to represent the calculation process of the directions of fault F and fracture J. The lengths of f1, f2, f3 and the lengths of j1, j2 are only used to represent relative magnitude values. The lengths of fault F and fracture J neither represent their absolute magnitude values nor represent their relative magnitude values with other values (f or j).

[0103] For the same fault strike direction and the direction of in-situ stress, there are usually two representation methods, namely one direction in the 0-180° interval and one direction in the 0-360° interval. The difference in direction between the two representation methods is 180°. For the purpose of convenient and efficient calculation, the present invention uniformly adopts the direction in the 0-180° interval for representation and calculation when taking the direction value.

[0104] The fault throw and the width of the fracture zone are both statistically obtained by the method of taking the average value through multi-point measurement along the strike direction of the fault plane and the fracture plane. The fault throw can be the horizontal formation fault throw, the vertical formation fault throw, or other fault throws adopted in the industry, as long as it is suitable for the geological outcrop or geophysical exploration conditions in the area, accurate and easy to measure.

[0105] According to the direction α of fault F and the fault throw D in the area where the factory building is located, the direction β of fracture J and the fracture width W statistically obtained above, using the formula γ = (D·α + W·β) / (D + W), the direction γ of the geological structure plane G is calculated as γ = (2.05·123.56 + 0.28·56) / (2.05 + 0.28) = 115.44°.

[0106] The illustration of the calculation process can be seen in Figure 3 the calculation diagram of the direction of geological structure plane G.

[0107] It should be noted that: Figure 3The length of the fault layer F or the length of the fissure J is used to represent the relative magnitude of its length compared to the fissure J or the fault F. The length of the geological structure plane G represents neither its absolute magnitude nor its relative magnitude compared to other values (J or F).

[0108] A grading scheme for the development level of geological structure planes is formulated, that is, the development level of geological structure planes is divided according to industry specifications or practical experience in the grading of the development level of geological structure planes. In this embodiment, the inventor combines industry practices with the actual operation experience of the project to form a grading scheme for the development level of geological structure planes (see Table 1-1) based on regional tectonic geological surveys and regional seismic activity records to determine the development level of geological structure planes. Since there are three faults with a certain scale and displacement in the area where the proposed factory building is located, the displacements are 1.12 m, 0.65 m, and 0.28 m respectively, and the displacement of one of the faults exceeds 1 meter, and the combined displacement of the three faults reaches more than two meters; there are two fissures with a relatively large scale, and the widths of the fissures both reach more than 0.12 m, and there are about 780 fissures with a width less than 0.01 m in this area; based on the above measured data, combined with the regional geological survey data and the research on the tectonic background, according to the grading scheme for the development level of geological structure planes (see Table 1-1), the development level of geological structure planes is divided into: (Level 1) weakly developed geological structure planes, (Level 2) generally developed geological structure planes, (Level 3) strongly developed geological structure planes, (Level 4) intensely developed geological structure planes, where the highest level Max(L) of the development level of geological structure planes is 4. According to the grading scheme for the development level of geological structure planes, it is determined that the development level of the geological structure plane in the area where the factory building is located is Level 3 strongly developed geological structure plane, that is, the development level L of the geological structure plane G is 3.

[0109] It should be noted that the grading scheme for the development level of geological structure planes in Table 1-1 is only a feasible scheme, and other reasonable grading schemes in the industry can also be adopted, all of which can be used as the scheme and basis for grading the development level of the geological structure plane in the area where the factory building is located in the present invention.

[0110] Table 1-1 Grading Scheme for the Development Level of Geological Structure Planes

[0111]

[0112] Develop a ground stress classification scheme, that is, determine the ground stress classification scheme according to the recommended scheme for the initial ground stress classification of rock masses in "Definition of High Ground Stress and Its Qualitative and Quantitative Criteria" (see Table 2-1). The ground stress level can be divided into low ground stress, medium ground stress, and high ground stress, where the highest level of the ground stress level Max(T) = 3. The directions of the maximum horizontal principal stress of the ground stress measured by the stress relief method and the hydraulic fracturing method in the area where the factory building is located are 64° and 82° respectively (that is, the average value of the direction σ of the maximum horizontal principal stress of the ground stress is 73°), and the numerical values of the maximum horizontal principal stress of the ground stress are 13.4 Mpa and 14.2 Mpa respectively. Combining with the numerical value of the uniaxial compressive strength of the rock measured in the project area, it is determined through calculation that the ground stress in the area where the factory building is located belongs to the first-level ground stress among the three-level ground stresses, that is, low ground stress, that is, the numerical level T of the maximum horizontal principal stress σ1 of the ground stress = 1 (the 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 the existing technology. The specific calculation process of the strength stress ratio belongs to the existing technology and will not be elaborated here).

[0113] Table 2-1 Recommended Scheme for Initial Ground Stress Classification of Rock Masses

[0114]

[0115] Among them, 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 diagram: Project the direction γ = 115.44° of the geological structure plane G, the development level L = 3 of the geological structure plane G, the direction σ = 73° of the maximum horizontal principal stress of the ground stress, and the numerical level T = 1 of the maximum horizontal principal stress of the ground stress into the azimuth diagram respectively (L = 3, Max(L) = 4, T = 1, Max(T) = 3); The specific projection method is: the radius value r of the circle = Max(Max(L), Max(T)), where Max(X) represents the maximum value in the X sequence, that is, the radius value r of the circle is the larger value of Max(L) and Max(T), that is, r takes the value of 4. In the azimuth diagram, the length of the geological structure plane G is L·r / Max(L), that is, r·3 / 4, and the length of the maximum horizontal principal stress of the ground stress is T·r / Max(T), that is, r·1 / 3 (see Figure 4 ).

[0117] Setting of advantageous conditions: According to the usual design principles in the industry, that is, the axis of the factory building intersects with the geological structure plane at a large angle and intersects with the direction of the maximum horizontal principal stress of the ground stress at a small angle, set the advantageous angle θ = 90° between the axis of the factory building and the direction of the geological structure plane, and the advantageous angle η = 0° between the axis of the factory building and the direction of the maximum horizontal principal stress respectively.

[0118] Target azimuth interval selection: Taking the direction of the geological structure plane as the boundary, the azimuth map is divided into two semi - circles, namely the first semi - circle and the second semi - circle (see Figure 5 ), in any one of the semi - circles (such as the first semi - circle), select the target azimuth interval where the included angle between the direction of the geological structure plane and the direction of the maximum horizontal principal stress of the in - situ stress is not less than 90° (see Figure 6 ).

[0119] Calibration of the axis direction: On the circumference corresponding to the target azimuth interval, divide the circular interval between the maximum horizontal principal stress of the in - situ stress and the geological structure reconstruction plane into (T·Max(L)+L·Max(T)) = 13 equal segments (see Figure 7 ); from the direction of the maximum horizontal principal stress of the in - situ stress to the geological structure reconstruction plane, at the T·Max(L) = 4th equal segment, mark a landmark point, draw a ray from the center of the circle to the landmark point, and extend the ray 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 (see Figure 8 ).

[0120] Embodiment 2

[0121] In this embodiment, a method for determining the axis direction of an underground powerhouse of a pumped - storage power station, except that the geological structure plane development level division scheme is different from that in Embodiment 1, the remaining steps are the same as those in Embodiment 1. In this embodiment, the inventor summarized a large number of actual production operation experiences of previous exploration projects and formed a geological structure plane development level division scheme based on the geological structure plane development density method (see Table 1 - 2).

[0122] Table 1 - 2 Geological structure plane development level division scheme (dividing the development level of geological structure planes according to the geological structure plane development density)

[0123]

[0124] The calculation formula for the geological structure plane development density is: Geological structure plane development density = number of faults+(number of fissures / 65), unit: number / 100m.

[0125] Embodiment 3

[0126] In this embodiment, a method for determining the axis direction of an underground powerhouse of a pumped - storage power station, except that the geological structure plane development level division scheme is different from that in Embodiment 1, the remaining steps are the same as those in Embodiment 1. In this embodiment, the inventor summarized a large number of actual production operation experiences of previous exploration projects and formed another geological structure plane development level division scheme based on the ratio of the sum of the fault throw and the width of the fissure zone to the length of the powerhouse along the axis direction (see Table 1 - 3).

[0127] Table 1-3 Classification Scheme for the Development Grade of Geological Structural Planes (classified according to the ratio of the sum of the fault throw and the width of the fracture zone to the length of the powerhouse along the axial direction)

[0128]

[0129]

[0130] Regarding which classification scheme for the development grade of geological structural planes in Examples 1, 2, and 3 is better, the present invention does not make a judgment. As long as the classification scheme for the development grade of geological structural planes can provide a certain basis for classifying the development grade of geological structural planes, enabling ordinary technical personnel in the industry to obtain the basis and classification situation for the development grade of geological structural planes from the corresponding classification scheme, and based on this, being able to judge the development grade of geological structural planes in the area where the powerhouse project is located.

[0131] Example 4

[0132] In this example, a method for determining the axial direction of an underground powerhouse of a pumped-storage power station is the same as that in Example 1 for the rest of the steps, except that the formulated in-situ stress classification scheme is different from that in Example 1. In this example, the in-situ stress classification scheme is determined according to the high initial stress classification criterion in the "Code for Geotechnical Investigation" (GB50021-94) (see Table 2-2).

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

[0134]

[0135] Example 5

[0136] In this example, a method for determining the axial direction of an underground powerhouse of a pumped-storage power station is the same as that in Example 1 for the rest of the steps, except that the formulated in-situ stress classification scheme is different from that in Example 1. In this example, the in-situ stress classification scheme is determined according to the initial in-situ stress classification criterion of rock masses in the "Code for Geological Investigation of Water Conservancy and Hydropower Projects" (GB50287-2016) (see Table 2-3).

[0137] Table 2-3 Initial In-situ Stress Classification Criterion of Rock Masses in the "Code for Geological Investigation of Water Conservancy and Hydropower Projects" (GB50287-2016) It should be noted that the above in-situ stress grading scheme is only a feasible scheme for in-situ stress grading. The in-situ stress grading schemes commonly adopted in the industry include many other related grading suggestion schemes, all of which can be used as the scheme and basis for grading the maximum horizontal principal stress of the in-situ stress in the area where the plant is located in the present invention. At present, there is no unified standard for the specific scheme of in-situ stress grading in the industry. Regarding which grading scheme is better, the present invention does not make any judgment. As long as the grading scheme can provide a certain basis for in-situ stress grading, enabling ordinary technical personnel in the industry to obtain the highest grade of in-situ stress from the corresponding grading scheme and judge the in-situ stress grade in the area where the plant is located. As for the specific judgment method and calculation method of the in-situ stress grade in the area where the plant is located, this belongs to the prior art in this field and is not the purpose of the present invention either, so the present invention will not elaborate on this.

[0138] Example 6

[0139] Experimental verification: Set up physical simulation experiments or numerical simulation experiments 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 foregoing embodiments. For the first underground powerhouse axis direction with deviations in the experimental results, comprehensively analyze the rationality of the parameter settings and make adjustments; Set up control experiments for existing underground powerhouses, build new underground powerhouses according to the first underground powerhouse axis direction, and verify the rationality of the first underground powerhouse axis direction by comparing the structural stabilities of the existing underground powerhouses and the newly built underground powerhouses. For the first underground powerhouse axis direction with deviations in the experimental results, comprehensively analyze the rationality of the parameter settings and make adjustments.

[0140] Example 7

[0141] A method for the construction of an underground powerhouse of a pumped-storage power station, characterized by comprising the following steps:

[0142] (1) Use the method for determining the axis direction of the underground powerhouse in the foregoing Embodiment 1 or 2 to determine the axis direction of the underground powerhouse as the first underground powerhouse axis direction;

[0143] (2) On the basis of the first underground powerhouse axis direction, comprehensively consider the actual working conditions of surrounding rock stability, powerhouse burial depth, and the layout direction of the water conveyance and power generation system, and adjust the first underground powerhouse axis direction to obtain the second underground powerhouse axis direction;

[0144] (3) Carry out the construction of the underground powerhouse according to the second underground powerhouse axis direction.

[0145] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for determining the axis direction of an underground powerhouse of a pumped-storage power station, characterized in that It includes the following steps: S1. Element determination: Formulate a grading scheme for the development level of geological structural planes, and obtain the highest level Max(L) of the development level of geological structural planes; measure the direction γ of the geological structural planes in the area where the plant is located, and determine the development level L of the geological structural planes in the area where the plant is located; Formulate a grading scheme for in-situ stress, and obtain the highest level Max(T) of the in-situ stress level; measure the direction σ of the maximum horizontal principal stress of the in-situ stress in the area where the plant is located and the numerical level T of the maximum horizontal principal stress of the in-situ stress; S2. Axis diagramming: Project the direction γ and development level L of the geological structural planes, and the direction σ and numerical level T of the maximum horizontal principal stress of the in-situ stress onto an azimuth diagram respectively. According to the dominant angle between the plant axis and the direction of the geological structural planes, and the dominant angle between the plant axis and the direction of the maximum horizontal principal stress, mark the direction ε of the first underground plant axis under the influence of geology and in-situ stress on the azimuth diagram.

2. The method for determining the axis direction of the underground powerhouse of a pumped-storage power station according to claim 1, characterized in that The specific steps of the S2. Axis diagramming include the following: S2.

1. Azimuth diagram construction: Construct a 0-360° azimuth diagram. In the azimuth diagram, the direction angles on the circumference represent the direction of the geological structural planes and the direction of the maximum horizontal principal stress of the in-situ stress. The radius value r of the circle = Max(Max(L), Max(T)), and the radius value r of the circle is the larger value of Max(L) and Max(T); S2.

2. Projecting the azimuth diagram: Project the geological structural planes and the maximum horizontal principal stress of the in-situ stress onto the azimuth diagram respectively according to the direction γ of the geological structural planes and the development level L of the geological structural planes, and the direction σ of the maximum horizontal principal stress of the in-situ stress and the numerical level T of the maximum horizontal principal stress of the in-situ stress. Among them, the length of the geological structural plane G is r·L / Max(L), and the length of the maximum horizontal principal stress of the in-situ stress is r·T / Max(T); S2.

3. Setting of dominant conditions: Respectively set the dominant angle between the plant axis and the direction of the geological structural planes as θ, and the dominant angle between the plant axis and the direction of the maximum horizontal principal stress as η; S2.

4. Selection of the target azimuth interval: Divide the azimuth diagram into two semi-circles with the direction of the geological structural planes as the boundary. In any one of the semi-circles, select the target azimuth interval where the angle between the direction of the geological structural planes and the direction of the maximum horizontal principal stress of the in-situ stress is not less than 90°; S2.

5. Marking the axis direction: On the circumference corresponding to this target azimuth interval, divide the circumferential interval between the maximum horizontal principal stress of the in-situ stress and the geological structural reconstruction plane into (T·Max(L)+L·Max(T)) equal segments; from the direction of the maximum horizontal principal stress of the in-situ stress to the geological structural reconstruction plane, mark a marked point at the T·Max(L)th equal segment; draw a ray from the center of the circle to the marked point, and extend the ray to the circumference to form an intersection point. The direction angle represented by the intersection point is the direction ε of the first underground plant axis.

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

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

5. The method for determining the axis direction of the underground powerhouse of a pumped-storage power station according to claim 4, wherein When there are multiple faults f1, f2, f3,..., fn in the area where the powerhouse is located, the direction of the faults and the fault throw refer to the combined direction α of the multiple faults and the combined fault throw D of the multiple faults, where: The combined direction α of 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 throw D of n faults = (D (F1) + D (F2) + D (F3) + … + D (Fn) ); Among them, α (f1) , α (f2) , α (f3) , …, α (fn) respectively represent the directions of the 1st, 2nd, 3rd, …, nth faults, which are represented in the direction of 0 - 180°; D (f1) , D (f2) , D (f3) , …, D (fn) respectively represent the throw of the 1st, 2nd, 3rd, …, nth faults; and / or When there are multiple fissures j1, j2, j3,..., jn in the area where the powerhouse is located, the direction β of the fissures and the fissure width W refer to the combined direction β of the multiple fissures and the combined width W of the multiple fissures, where: The comprehensive direction β of n fractures = (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 comprehensive width W of n fractures = (W (j1) + W (j2) + W (j3) + … + W (jn) ); Among them, β (j1) , β (j2) , β (j3) , …, β (jn) respectively represent the directions of the 1st, 2nd, 3rd, …, nth fissures, which are represented in the direction of 0 - 180°; W (J1) , W (J2) , W (J3) , …, W (Jn) respectively represent the width values of the 1st, 2nd, 3rd, …, nth fissures; The direction of the faults and the direction of the fissures refer to the strike directions of the faults and fissures.

6. The method for determining the axis direction of the underground powerhouse of a pumped-storage power station according to claim 5, characterized in that When there are multiple faults f1, f2, f3, ..., fn in the area where the powerhouse is located, and / or when there are multiple fissures j1, j2, j3, ..., jn in the area where the powerhouse is located, D (f1) , D (f2) , D (f3) ,…,D (fn) Sort the faults into a sequence of fault throws, and / or sort the W (J1) , W (J2) , W (J3) , …, W (Jn) The crack width sequence is formed by sorting, and the smaller values ​​and corresponding faults and / or cracks in the fault distance sequence and / or crack width sequence that are ranked later are removed according to a certain ratio to correct the sequence and avoid noise interference.

7. The method for determining the axis direction of the underground powerhouse of a pumped-storage power station according to claim 1, wherein Determining the development grade L of the geological structure plane in the area where the powerhouse is located: According to the development situation of the geological structure plane G, combined with the regional geological survey data, determine the development grade L of the geological structure plane in the area where the powerhouse is located according to the geological structure plane development grade division scheme; the development situation of the geological structure plane G includes the number of faults, the fault throw D of the faults, the number of fissures, the fissure width W of the fissures, and the occurrence and distribution relationship of the faults and fissures. Determining the direction σ of the maximum horizontal principal stress of the in-situ stress and the numerical grade T of the maximum horizontal principal stress of the in-situ stress in the area where the powerhouse is located: Measuring the direction of the maximum horizontal principal stress of the in-situ stress and the numerical value of the maximum horizontal principal stress of the in-situ stress using the stress relief method or the hydraulic fracturing method, and determining the numerical grade of the maximum horizontal principal stress of the in-situ stress in the area where the powerhouse is located according to the in-situ stress grading scheme based on the numerical value of the maximum horizontal principal stress of the in-situ stress.

8. The method for determining the axis direction of the underground powerhouse of a pumped storage power station according to claim 1, wherein The method adopted for the geological structure plane development grade division scheme is as follows: The calculation formula for the development density of the geological structure plane is: Development density of the geological structure plane = Number of faults + (Number of fissures / 65), unit: number / 100m. The division of the geological structure plane development grade is shown in the following table: and / or The in-situ stress grading scheme refers to the grading criteria for rock mass in-situ stress stipulated in engineering construction standards including the Geotechnical Engineering Investigation Code and the Geological Investigation Code for Water Conservancy and Hydropower Projects.

9. The method for determining the axis direction of the underground powerhouse of a pumped storage power station according to claim 1, wherein It also includes: S3. Experimental verification: Set up a physical simulation experiment or a numerical simulation experiment to verify the rationality of the axis direction of the first underground powerhouse. For the axis direction of the first underground powerhouse with deviations in the experimental results, comprehensively analyze the rationality of the parameter settings and make adjustments. and / or Set up a control experiment for the existing underground powerhouse, build a new underground powerhouse according to the axis direction of the first underground powerhouse, and verify the rationality of the axis direction of the first underground powerhouse by comparing the structural stability of the existing underground powerhouse and the newly built underground powerhouse. For the axis direction of the first underground powerhouse with deviations in the experimental results, comprehensively analyze the rationality of the parameter settings and make adjustments.

10. A construction method for an underground powerhouse of a pumped-storage power station, characterized in that It includes the following steps: (1) Using the method for determining the axis direction of the underground powerhouse of a pumped-storage power station according to any one of claims 1-9, determine the axis direction of the underground powerhouse as the first axis direction of the underground powerhouse; (2) On the basis of the first axis direction of the underground powerhouse, comprehensively consider the actual conditions of the surrounding rock stability, the buried depth of the powerhouse, and the layout direction of the water conveyance and power generation system, and adjust the first axis direction of the underground powerhouse to obtain the second axis direction of the underground powerhouse; (3) Carry out the construction of the underground powerhouse according to the second axis direction of the underground powerhouse.

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