Underground engineering karst calculation method based on borehole constraint tomography inversion

Abstract

The invention relates to the field of underground engineering exploration methods, in particular to an underground engineering karst calculation method based on borehole constraint tomography inversion, which comprises the following steps: determining the layout mode of an exploration line and the distance between two adjacent exploration points on the same exploration line; surveying and calculating the thickness Hi (i = 1, 2, 3,..., a) of the karst section around the construction main body; the volume V of the karst around the construction body is calculated according to the equivalent thickness D of the section of the karst around the construction body and the distribution area A of the karst around the construction body in the horizontal direction, D is calculated according to Hi, and A is obtained according to the projection of the section of the karst in the horizontal direction; the system adopts the karst volume calculation method; the device is used for executing the karst volume calculation method, through the method, the estimation precision of the expected karst grouting amount is improved, the project cost is reduced, and the project construction period is shortened.

Description

Technical Field

[0001] The invention relates to the field of underground engineering survey methods, and in particular to an underground engineering karst calculation method based on borehole constrained tomography inversion. Background Art

[0002] Karst is a general term for various geological effects, forms and phenomena produced by the dissolution of soluble rocks by water, such as karst caves and tiankeng landforms. When the underground engineering line of urban rail transit passes through areas with strong karst development, karst is often distributed on the top, body and bottom of the tunnel. For areas with karst distributed around the top and body of the tunnel, problems such as top collapse, shield machine eccentricity, head drop and karst water outburst are prone to occur during the excavation process. For areas with karst distributed below the bottom of the tunnel, problems such as shield machine head drop, sudden fall of machinery or personnel, water and mud inrush are prone to occur during the excavation process. Therefore, it is necessary to adopt the grouting method to fill the karst around the underground engineering on the ground in advance according to factors such as the scale of karst and the properties of karst filling materials, combined with engineering construction experience.

[0003] The premise for reasonably determining the amount of karst grouting is to determine the volume of each karst, but karst development is characterized by significant heterogeneity. At present, when determining the karst volume of underground projects, the karst volume in the construction area is often evaluated as a whole. However, the construction area contains different types of underground projects, and the main building forms and volumes of various underground projects are different. Therefore, when determining the karst volume of underground projects, the existing technology will have large deviations in karst volume estimation due to different types of underground projects, which will lead to large deviations between the expected karst grouting volume and the actual grouting volume, increasing project costs and project construction periods. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem in the prior art that when determining the karst volume of underground engineering, there is a large deviation in the estimation of the karst volume due to the different types of underground engineering, which leads to a large deviation between the expected karst grouting volume and the actual grouting volume, increasing the project cost and project schedule, and to provide an underground engineering karst calculation method based on borehole constrained tomography inversion.

[0005] In a first aspect, the present invention provides a method for calculating karst volume, comprising the following steps:

[0006] S1: Determine the layout of the survey line according to the type of the main construction body of the underground project, and determine the distance between two adjacent survey points on the same survey line according to the degree of karst development around the main construction body;

[0007] S2: Survey the area around the construction site through the survey line, and calculate the thickness H of the karst profile around the construction site based on the survey data i(i=1, 2, 3, ..., a), where i is the number of the karst section and a is a constant;

[0008] S3: Calculate the karst volume V around the construction body according to the equivalent thickness D of the karst profile around the construction body and the horizontal distribution area A of the karst around the construction body, where D is calculated according to H i It is calculated that A is obtained based on the horizontal projection of the karst profile.

[0009] In the prior art, those skilled in the art can determine the layout of the survey line based on the type of construction subject of the underground project through engineering experience.

[0010] Among them, one exploration point corresponds to one karst profile.

[0011] The thickness of the karst profile refers to the distance from the top to the bottom of the karst space in the vertical direction.

[0012] In S2, a karst profile is obtained through line surveying, and the extension direction of the karst profile is the vertical direction.

[0013] In S3, several karst sections obtained along the vertical direction are projected in the horizontal direction to obtain several line segments distributed in the horizontal direction. The area surrounded by these line segments is the horizontal distribution range of the karst around the construction body, and the area of ​​the distribution range is A.

[0014] Through this method, according to different types of underground projects, the location of the exploration line and the distance between the exploration points are reasonably arranged, and the elastic wave cross-hole CT method is used to divide the karst into multiple sections. According to the average thickness of each section, the equivalent thickness and projection area of ​​the karst are finally determined, which reduces the deviation of the karst volume estimation, thereby improving the estimation accuracy of the expected karst grouting volume, reducing the project cost and project period, and realizing the economy and rationality of the project.

[0015] Preferably, when the main construction type of the underground project is an underground station, the survey line is laid out in the following manner: one survey line is laid out along the center line of the foundation pit of the underground station, and one survey line is laid out along both sides of the enclosure structure of the underground station;

[0016] Preferably, when the main construction type of the underground project is a pair of tunnels arranged side by side, the survey line is laid out in the following manner: one survey line is laid out in the middle of the two tunnels along the longitudinal direction of the tunnel, and one survey line is laid out outside the two tunnels along the longitudinal direction of the tunnel.

[0017] Preferably, a single exploration point is provided with a pair of seismic wave transmitting and receiving devices, and the seismic wave transmitting and receiving devices are used to survey the area around the construction body by using an elastic wave cross-hole CT method.

[0018] The karst development degree is confirmed according to the "Technical Standards for Building Foundations in Karst Areas" or the technical manual for on-site construction. The karst development degree includes strong development, medium development and weak development. When the karst development degree is strong, the distance between two adjacent exploration points on the same survey line is 10-15m; when the karst development degree is medium, the distance between two adjacent exploration points on the same survey line is 15-20m; when the karst development degree is weak, the distance between two adjacent exploration points on the same survey line is 20-30m.

[0019] The karst development degree and the corresponding exploration point spacing are obtained according to the technical manual. When the main construction type of the underground project is an underground station, for areas with strong karst development, the exploration point spacing is 10-15m, preferably 10m; for areas with medium karst development, the exploration point spacing is 15-17m, preferably 15m; for areas with weak karst development, the exploration point spacing is 20-22m, preferably 20m;

[0020] When the main construction type of the underground project is a double tunnel set side by side, for areas with strong karst development, the exploration point spacing is 10-15m, preferably 15m; for areas with medium karst development, the exploration point spacing is 15-20m, preferably 20m; for areas with weak karst development, the exploration point spacing is 20-30m, preferably 30m.

[0021] Preferably, in S2, the thickness H of the karst section around the construction subject is calculated. i The method is as follows: project the length of the karst space measured at a single exploration point to the horizontal direction to obtain the plane projection length L i (i=1,2,3,...,a), according to the area S of the karst section i and projection length L i Calculate the thickness H of the karst profile corresponding to a single exploration point i (i=1,2,3,...,a), the calculation formula is as follows:

[0022] H i =S i / L i .

[0023] Plane projection length L i Refers to the distance between the two points farthest apart in the horizontal direction within the karst space.

[0024] The area of ​​the karst section S i The profile is drawn based on the survey data and obtained by calculating the area of ​​the profile.

[0025] Preferably, the calculation formula of the equivalent thickness D is:

[0026]

[0027] Where n represents the number of karst sections.

[0028] Preferably, the value range of n is 3-8.

[0029] Preferably, the volume V of the karst around the construction body is calculated according to the equivalent thickness D and the distribution area A, and the calculation formula of V is: V=A·D.

[0030] In a second aspect, the present invention provides a karst volume calculation system, which adopts the above-mentioned karst volume calculation method, including a survey line layout module, a karst parameter calculation module, and a karst volume calculation module.

[0031] The survey line layout module is used to determine the layout mode of the survey line according to the type of the construction subject of the underground project, and to determine the distance between two adjacent survey points on the same survey line according to the degree of karst development around the construction subject;

[0032] The karst parameter calculation module is used to calculate the thickness H of each karst section. i , the horizontal distribution area A of karst, and the equivalent thickness D of the karst section;

[0033] The karst volume calculation module is used to calculate the karst volume around the construction subject.

[0034] Through this system, the convenience of using the karst volume calculation method is improved.

[0035] In a third aspect, the present invention provides a karst volume calculation device, comprising at least one processor and a memory communicatively connected to the at least one processor; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the karst volume calculation method described above.

[0036] Through this setting, the convenience of using the karst volume calculation method is improved.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. The present invention provides a method for calculating karst volume. According to the method, according to different types of underground projects, the positions of exploration lines and the distances between exploration points are reasonably arranged, and the elastic wave cross-hole CT method is adopted to divide the karst into multiple sections. According to the average thickness of each section, the equivalent thickness and projection area of ​​the karst are finally determined, thereby reducing the deviation amplitude of karst volume estimation, thereby improving the estimation accuracy of expected karst grouting volume, reducing project costs and project duration, and achieving the economy and rationality of the project;

[0039] 2. The present invention provides a karst volume calculation system, through which the convenience of using the karst volume calculation method is improved;

[0040] 3. The present invention provides a device for calculating the karst volume. Through this configuration, the convenience of using the method for calculating the karst volume is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a flow chart of a method for calculating karst volume in Example 1 provided by the present invention;

[0042] Figure 2 It is a plan view of the layout of the underground station exploration line of Example 1 provided by the present invention;

[0043] Figure 3 It is a schematic plan view of the layout of the double tunnel exploration lines arranged side by side in Example 1 provided by the present invention;

[0044] Figure 4 It is a schematic diagram of the horizontal projection of the karst of Example 1 provided by the present invention;

[0045] Figure 5 It is a schematic diagram of the karst section of Example 1 provided by the present invention. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below in conjunction with specific embodiments. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0047] Unless otherwise specified, in the description of the specific embodiments of the present invention, the terms indicating the orientation or position relationship such as "up", "down", "left", "right", "center", "inside", "outside", etc. are all expressions based on the orientation or position relationship shown in the drawings, or are the orientation or position relationship when the invented product / equipment / device is usually used. These terms of orientation or position relationship are only for the convenience of describing the scheme of the present invention or simplifying the description in the specific embodiments, so as to facilitate the technicians to quickly understand the scheme, and do not indicate or imply that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore cannot be understood as a limitation on the present invention.

[0048] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel" and the like appear, it does not mean that the corresponding devices / components / elements are required to be absolutely horizontal or vertical or overhanging or parallel, but may be slightly tilted or have deviations. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but may be slightly tilted. Alternatively, it can be simplified to mean that the corresponding devices / components / elements are set in directions such as "horizontal", "vertical", "overhanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably an error / deviation within ±8%, more preferably an error / deviation within ±6%, more preferably an error / deviation within ±5%, and more preferably an error / deviation within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present invention.

[0049] In addition, the expressions “first”, “second”, “third”, etc., which appear in the terms, are merely used to distinguish the description of the same or similar components and should not be understood as emphasizing or implying the relative importance of specific components.

[0050] In addition, in the description of the embodiments of the present invention, "several", "plurality" and "a number" represent at least 2. It can be any number such as 2, 3, 4, 5, 6, 7, 8, 9, and even more than 9.

[0051] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, the terms "set", "install", "connect", "connected", "provided with", "laid", and "arranged" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, and can be welding, riveting, bolting, threading, and other commonly used connection means in the field. This connection can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0052] Example 1

[0053] As attached Figure 1-Figure 5 As shown, this embodiment provides a method for calculating karst volume, comprising the following steps:

[0054] S1: Determine the layout of the survey line according to the type of the main construction body of the underground project, and determine the distance between two adjacent survey points on the same survey line according to the degree of karst development around the main construction body;

[0055] S2: Survey the area around the construction site through the survey line, and calculate the thickness H of the karst profile around the construction site based on the survey data i (i=1, 2, 3, ..., a), where i is the number of the karst section and a is a constant;

[0056] S3: Calculate the karst volume V around the construction body according to the equivalent thickness D of the karst profile around the construction body and the horizontal distribution area A of the karst around the construction body, where D is calculated according to H i It is calculated that A is obtained based on the horizontal projection of the karst profile.

[0057] In the prior art, those skilled in the art can determine the layout of the survey line based on the type of construction subject of the underground project through engineering experience.

[0058] Among them, one exploration point corresponds to one karst profile.

[0059] The thickness of the karst profile refers to the distance from the top to the bottom of the karst space in the vertical direction.

[0060] In S2, a karst profile is obtained through line surveying, and the extension direction of the karst profile is the vertical direction.

[0061] In S3, several karst sections obtained along the vertical direction are projected in the horizontal direction to obtain several line segments distributed in the horizontal direction. The area surrounded by these line segments is the horizontal distribution range of the karst around the construction body, and the area of ​​the distribution range is A.

[0062] Through this method, according to different types of underground projects, the location of the exploration line and the distance between the exploration points are reasonably arranged, and the elastic wave cross-hole CT method is used to divide the karst into multiple sections. According to the average thickness of each section, the equivalent thickness and projection area of ​​the karst are finally determined, which reduces the deviation of the karst volume estimation, thereby improving the estimation accuracy of the expected karst grouting volume, reducing the project cost and project period, and realizing the economy and rationality of the project.

[0063] According to the drilling data of the initial exploration stage of the target area, the geological environment of the area where the urban rail transit passes through is complex, karst is well developed, and the soluble rock stratum of the underground project is the Carboniferous Shidengzi Formation limestone, which is a typical soluble rock. Affected by the subtropical marine climate, the area is hot and rainy with abundant precipitation. The surface rivers belong to the coastal water system of eastern Guangdong. Affected by the topography, surface water and groundwater converge from mountains and hills to river valleys and plains, and are radially injected into the bay. Under the action of groundwater erosion, the bedrock at the top of the soluble rock in the area fluctuates greatly, the karst development characteristics are obvious, and the karst grooves, karst troughs and caves are relatively developed. The drilling in the karst interval revealed a cave rate of 67.14% and a linear karst rate of 22.47%. According to the "Technical Standards for Building Foundations in Karst Areas" (GB / T51238-2018), the karst development level in the target area is strongly developed.

[0064] Therefore, for the twin tunnels set up side by side, the layout of the survey line is as follows: one survey line is laid out in the middle of the two tunnels along the longitudinal direction of the tunnel, and one survey line is laid out on the outside of the two tunnels along the longitudinal direction of the tunnel. The distance between adjacent survey points is 15m. The layout position of the survey line is similar to the preset position of the tunnel. Figure 3 As shown;

[0065] For underground stations, the layout of the survey line is as follows: one survey line is laid out along the center line of the underground station foundation pit, and one survey line is laid out along both sides of the underground station enclosure structure. The distance between adjacent survey points is 10m. The survey line layout position is similar to the preset position of the underground station. Figure 2 shown.

[0066] A pair of seismic wave transmitting and receiving devices are arranged at each exploration point, and the seismic wave transmitting and receiving devices are used to survey the surroundings of the construction body by using the elastic wave cross-hole CT method.

[0067] The thickness H of the karst section around the main construction area is calculated in S2 i The method is as follows: project the length of the karst space measured at a single exploration point to the horizontal direction to obtain the plane projection length L i (i=1,2,3,...,a), according to the area S of the karst section i and projection length L i Calculate the thickness H of the karst profile corresponding to a single exploration point i (i=1,2,3,...,a), the calculation formula is as follows:

[0068] H i =S i / L i ;

[0069] Plane projection length L i Refers to the distance between the two points farthest apart in the horizontal direction within the karst space.

[0070] The area of ​​the karst section S i The profile is drawn based on the survey data and obtained by calculating the area of ​​the profile.

[0071] The calculation formula of the equivalent thickness D is:

[0072]

[0073] Where n represents the number of karst sections, n=3.

[0074] According to the equivalent thickness D and the distribution area A, the volume V of the karst around the construction body is calculated, and the calculation formula of V is: V=A·D.

[0075] According to the above steps, the total volume of karst in the target area is V, and the parameters of karst in the target area are shown in Table 1:

[0076] Table 1 Karst parameters in the target area

[0077] Karst distribution area A Equivalent thickness D Karst volume V <![CDATA[159.83m 2 ]]> 7.86m <![CDATA[1256.26m 3 ]]>

[0078] Example 2

[0079] This embodiment provides a karst volume calculation system, which adopts a karst volume calculation method described in Embodiment 1, including a survey line layout module, a karst parameter calculation module, and a karst volume calculation module.

[0080] The survey line layout module is used to determine the layout mode of the survey line according to the type of the construction subject of the underground project, and to determine the distance between two adjacent survey points on the same survey line according to the degree of karst development around the construction subject;

[0081] The karst parameter calculation module is used to calculate the thickness H of each karst section. i , the horizontal distribution area A of karst, and the equivalent thickness D of the karst section;

[0082] The karst volume calculation module is used to calculate the karst volume around the construction subject.

[0083] Through this system, the convenience of using the karst volume calculation method is improved.

[0084] Example 3

[0085] This embodiment provides a karst volume calculation device, including at least one processor and a memory communicatively connected to the at least one processor; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute a karst volume calculation method described in Example 1.

[0086] Through this setting, the convenience of using the karst volume calculation method is improved.

[0087] 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 in the protection scope of the present invention.

Claims

1. A method for calculating karst volume, characterized in that: The following steps are involved: S1: Determine the layout of the survey line according to the type of the main construction body of the underground project, and determine the distance between two adjacent survey points on the same survey line according to the degree of karst development around the main construction body; S2: Survey the area around the construction site through the survey line, and calculate the thickness H of the karst profile around the construction site based on the survey data i (i=1, 2, 3, ..., a), where i is the number of the karst section and a is a constant; S3: Calculate the karst volume V around the construction body according to the equivalent thickness D of the karst profile around the construction body and the horizontal distribution area A of the karst around the construction body; where D is calculated according to H i It is calculated that A is obtained based on the horizontal projection of the karst profile.

2. The method for calculating karst volume according to claim 1, characterized in that: When the main construction type of the underground project is an underground station, the layout of the survey line is as follows: one survey line is laid out along the center line of the underground station foundation pit, and one survey line is laid out along both sides of the underground station enclosure structure; When the main construction type of the underground project is a pair of tunnels set side by side, the survey line is laid out as follows: one survey line is laid out in the middle of the two tunnels along the longitudinal direction of the tunnel, and one survey line is laid out on the outside of the two tunnels along the longitudinal direction of the tunnel.

3. A method for calculating karst volume according to claim 2, characterized in that: A single exploration point is provided with a pair of seismic wave transmitting and receiving devices, and the seismic wave transmitting and receiving devices are used to survey the area around the construction body by using the elastic wave cross-hole CT method.

4. The method for calculating karst volume according to claim 1, characterized in that: The karst development degree includes strong development degree, medium development degree and weak development degree. When the karst development degree is strong development, the distance between two adjacent exploration points on the same exploration line is 10-15m; when the karst development degree is medium development, the distance between two adjacent exploration points on the same exploration line is 15-20m; when the karst development degree is weak development, the distance between two adjacent exploration points on the same exploration line is 20-30m.

5. The method for calculating karst volume according to claim 1, characterized in that: The thickness H of the karst section around the main construction area is calculated in S2 i The method is as follows: project the length of the karst space measured at a single exploration point to the horizontal direction to obtain the plane projection length L i (i=1,2,3,...,a), according to the area S of the karst section i and projection length L i Calculate the thickness H of the karst profile corresponding to a single exploration point i (i=1,2,3,...,a), the calculation formula is as follows: H i =S i / L i 。 6. A method for calculating karst volume according to claim 5, characterized in that: The calculation formula of the equivalent thickness D is: Where n represents the number of karst sections.

7. A method for calculating karst volume according to claim 6, characterized in that: The value range of n is 3-8.

8. A method for calculating karst volume according to claim 6, characterized in that: According to the equivalent thickness D and the distribution area A, the volume V of the karst around the construction body is calculated. The calculation formula of V is: V = A·D.

9. A karst volume calculation system, characterized in that: A karst volume calculation method as claimed in any one of claims 1 to 8 is adopted, comprising a survey line layout module, a karst parameter calculation module and a karst volume calculation module, The survey line layout module is used to determine the layout mode of the survey line according to the type of the construction subject of the underground project, and to determine the distance between two adjacent survey points on the same survey line according to the degree of karst development around the construction subject; The karst parameter calculation module is used to calculate the thickness H of each karst section. i , the horizontal distribution area A of karst, and the equivalent thickness D of the karst section; The karst volume calculation module is used to calculate the karst volume around the construction subject.

10. A karst volume calculation device, characterized in that: comprising at least one processor, and a memory communicatively connected to the at least one processor; The memory stores instructions that can be executed by at least one processor, and the instructions are executed by at least one processor so that the at least one processor can execute the method for calculating the karst volume as described in any one of claims 1-8.

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