Karst area railway bridge engineering investigation dynamic control method

Abstract

The invention relates to a karst area railway bridge engineering investigation dynamic control method. Comprising the following steps: S100, preliminarily obtaining a karst distribution range of a bridge site area; s200, karst development information is obtained, wherein the karst development information comprises a plane karst development section, a karst development degree and a karst development depth; s300, according to the karst development information, determining preset positions of the abutments, and drilling at the determined preset positions of the abutments; s400, according to the drilling result, whether the preset positions of the abutments are appropriate or not is judged, and if yes, it is determined that the preset positions of the abutments are the construction positions of the abutments; and if not, adjusting the preset position of the abutment. According to the method, dynamic management of exploration is carried out, so that the exploration work is clear in purposiveness, and by optimizing the drilling positions, the drilling number and the drilling depth, the exploration quality is guaranteed, the exploration workload is reduced, and the exploration period is greatly shortened. The development of the geological exploration technology of the railway bridge engineering in the karst area is promoted, and the economic and social benefits are remarkable.

Description

Technical Field

[0001] The invention relates to the technical field of railway bridge engineering survey, and in particular to a railway bridge engineering survey method in a karst area. Background Art

[0002] Covered karst refers to karst covered by loose deposits of the Quaternary system, which is distributed in cities such as Guilin, Guangzhou, Hangzhou and Wuhan. With the large-scale rise of various railway transportation infrastructure construction, many engineering projects have to be carried out in karst areas. Due to the complexity, concealment and spatial heterogeneity of the development law of covered karst, a lot of survey work is often required to identify the karst and karst water distribution and development characteristics of the site. Drilling, as an intuitive and effective survey method, is used in railway bridge projects in karst areas. However, the piers of railway bridge projects in karst areas often need to be drilled pile by pile. The survey work is large-scale, deep, and dense. The cost of pier drilling is high, and it is impossible to identify the complex karst distribution characteristics with an extremely dense grid.

[0003] Therefore, it is necessary to propose a scientific, economical and technically feasible dynamic control method for karst railway bridge engineering survey, which can ensure the construction progress and project safety by optimizing the drilling position, number and depth, while greatly saving project investment. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a dynamic control method for railway bridge engineering survey in karst areas, comprising the following steps:

[0005] S100: Preliminary acquisition of the karst distribution range in the bridge site area;

[0006] S200: Acquire karst development information, wherein the karst development information includes planar karst development sections, karst development degrees, and karst development depths;

[0007] S300: Determine the preset positions of each pier according to the karst development information obtained in step S200, and perform drilling at the determined preset positions of the piers;

[0008] S400: judging whether the preset positions of the piers are suitable according to the drilling results of step S300, and if suitable, determining the preset positions of the piers as the pier construction positions; if not suitable, adjusting the preset positions of the piers.

[0009] Furthermore, the step S200 includes: obtaining prediction information and geophysical interpretation result information, and obtaining the karst development information through comprehensive determination of the prediction information and the geophysical interpretation result information.

[0010] Furthermore, the acquisition of the prediction information includes: according to the initially acquired karst distribution range of the bridge site area, dividing the karst development degree of the bridge site area according to the surface karst development density, and acquiring the prediction information.

[0011] Furthermore, the acquisition of the geophysical interpretation results information includes: setting a number of parallel geophysical exploration lines along the longitudinal direction of the bridge to be built, conducting karst geophysical exploration, and obtaining geophysical information on karst distribution in the bridge site area.

[0012] Furthermore, the step S300 specifically includes:

[0013] The bridge site is zoned according to the karst development degree based on the karst development information. The karst development degree includes an area with strong karst development, an area with medium karst development and an area with weak karst development. The preset position of the pier is determined based on the karst development degree zoning result, wherein the preset position of the pier avoids the area with strong karst development.

[0014] Furthermore, the step S300 further includes:

[0015] When the karst development degree zoning includes a strongly karst development area, the strongly karst development area is verified, and the verification method includes:

[0016] A plurality of verification holes are arranged in the area where karst is strongly developed. If at least one of the verification holes reveals that the degree of karst development is strongly developed, the verification result is accurate. If all the verification holes reveal that the degree of karst development is not strongly developed, the verification result is judged to be inaccurate, and the area where karst is strongly developed is downgraded to an area where karst is moderately developed.

[0017] Furthermore, the arrangement of the verification holes includes: arranging one verification hole under the central foundation pile and arranging four verification holes diagonally, and verifying through the verification holes to calibrate the degree of karst development.

[0018] Furthermore, the drilling of the preset position of the pier in the weakly developed karst area includes: setting a number of preliminary exploration holes at the pier arrangement position in the weakly developed karst area, drilling to the complete bedrock weakly weathered not less than 15m, and 10 to 15m below the pile end.

[0019] Furthermore, the drilling of the preset position of the pier in the medium-developed karst area includes: setting a number of preliminary exploration holes at the pier arrangement position in the medium-developed karst area, drilling to a depth of not less than 20m of weakly weathered intact bedrock and 10 to 15m below the pile end.

[0020] Furthermore, if the preliminary exploration hole reveals soluble rock, two corner exploration holes are arranged diagonally to the pier, and the corner exploration holes are drilled to a depth of not less than 15 m of intact bedrock that is weakly weathered and 10 to 15 m below the pile end.

[0021] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0022] The present invention establishes a comprehensive system of survey technology methods for railway bridge engineering in karst areas, proposes survey management concepts such as survey layout principles, gradual tracing of drilling holes, and dynamic control for bridge engineering in karst areas, implements dynamic management of survey technology, makes the survey work purposeful, and achieves optimization of drilling position, number, and hole depth, which not only ensures the survey quality, but also saves the survey workload and greatly shortens the survey cycle. It promotes the development of geological survey technology for railway bridge engineering in karst areas, and has significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A flow chart of the dynamic control method for engineering survey of railway bridges in karst areas provided by the present invention;

[0025] Figure 2-6 A schematic diagram of the arrangement of pier drilling holes in the dynamic control method for engineering survey of railway bridges in karst areas provided by the present invention. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0027] The present invention provides a dynamic control method for engineering survey of railway bridges in karst areas, comprising the following steps:

[0028] S100: Preliminary acquisition of the karst distribution range in the bridge site area;

[0029] S200: Acquire karst development information, wherein the karst development information includes planar karst development sections, karst development degree and karst development depth;

[0030] S300: Determine the preset positions of each pier according to the karst development information obtained in step S200, and perform drilling at the determined preset positions of the piers;

[0031] S400: judging whether the preset positions of the piers are suitable according to the drilling results of step S300, and if suitable, determining the preset positions of the piers as the pier construction positions; if not suitable, adjusting the preset positions of the piers.

[0032] Specifically, the engineering survey method for railway bridges in karst areas of the present application strengthens the overall control of the survey work and the dynamic management of the process, which is specifically manifested in the dynamic adjustment method for determining the karst drilling depth, including the drilling depth, drilling location arrangement and the number of drilling holes. While meeting the specifications, it avoids the exploration depth not meeting the design requirements and the waste of workload, so as to improve the efficiency, economic benefits and quality of geological drilling for railway bridge projects in karst areas.

[0033] In an optimized implementation method, the step S100 is specifically to fully collect, analyze and study the existing regional geology and hydrogeology, and on the basis of remote sensing interpretation and preliminary survey data, preliminarily obtain the karst distribution range of the bridge site through large-scale geological mapping, hydrogeological surveys combined with geological lithology and karst landform characteristics.

[0034] In an optimized implementation mode, the step S200 includes: obtaining prediction information and geophysical interpretation result information (i.e., geophysical information), and obtaining the karst development information through comprehensive determination of the prediction information and the geophysical interpretation result information.

[0035] Specifically, obtaining predictive information includes classifying the type and thickness of the covering layer and the degree of weathering of the underlying bedrock according to the results of field outcrop geological mapping and previous existing survey data, and classifying the degree of karst development in the bridge site area according to the density of surface karst development to obtain predictive information on karst development.

[0036] Specifically, obtaining geophysical interpretation results includes setting up several parallel geophysical exploration lines along the longitudinal direction of the bridge to be built, conducting karst geophysical exploration, and obtaining geophysical information on karst distribution in the bridge site. Based on the prediction information and geophysical information, the karst development information in the bridge site is obtained, and the karst development information includes the planar karst development section, karst development degree and karst development depth.

[0037] The degree of karst development includes areas with strong karst development, areas with moderate karst development, and areas with weak karst development. Among them, weak karst development is dominated by fissure-like karst or karst pores, and the permeability of the fissures is poor; the rate of encountering holes in the boreholes is less than 30%, the height of a single hole in the borehole karst cave is less than 1m, the linear karst rate is <1, and the cumulative height of the karst cave is less than 3m. Moderate karst development is that the dissolution along the fissures and layers expands into karst fissures or small caves, the connectivity of the fissures is poor, there is generally no concentrated runoff, and there are often fissure springs exposed; the rate of encountering holes in the boreholes is 30% to 60%, or the height of a single hole in the borehole karst cave is 1 to 3m, or the linear karst rate is 1 to 10, and the cumulative height of the karst caves is ≤5m. Strong karst development means significant dissolution along structural surfaces such as faults and layers, the development of small and medium-sized beaded caves, and the underground cave system has not yet formed, but the karst fissures are well connected, with small underground rivers or concentrated runoff, and karst fissure water gushing out; the drilling encounter rate is >60%, or the height of a single cave in the drilling is >3m, or the linear karst rate is >10, and the cumulative height of the cave is ≤10m. Non-strong karst development includes weak karst development and moderate karst development. In the process of pier arrangement, it is necessary to avoid pier arrangement in areas with strong karst development, and to explore the karst distribution in the bridge site area to ensure that the pier is set away from areas with strong karst development, improve the stability of the pier, and thus ensure the safety of the bridge.

[0038] In an optimized implementation mode, the step S300 specifically includes zoning the bridge site area according to the karst development degree according to the karst development information, and determining the preset position of the pier according to the karst development degree zoning result, wherein the preset position of the pier avoids the area with strong karst development. The preset position of the pier is preferably in the area with weak karst development.

[0039] Optimize the implementation method and carry out karst geophysical exploration in the bridge site area, including the following steps:

[0040] 1) Determine the geophysical exploration method based on the thickness of the overburden and underlying bedrock weathering layer;

[0041] When the covering layer is thin, at least one of the electrical profiling method, transient electromagnetic method, high-density electrical method, surface wave method, shallow seismic refraction method, and shallow seismic reflection wave method is used; when the covering layer is thick, at least one of the high-frequency magnetotelluric survey method, natural surface wave method, and micro-seismic method is used.

[0042] For the band-shaped abnormal area, tomographic detection is used for detection.

[0043] For larger-scale band anomalies, tomographic imaging detection is used to accurately determine the location and extension of the band anomalies; for smaller-scale band anomalies, tomographic imaging detection is used to conduct detailed investigations of small-scale caves and fillings.

[0044] 2) Three parallel geophysical exploration lines were arranged along the longitudinal centerline of the bridge and the left and right side foundation pile positions of the piers to conduct karst geophysical exploration, clarify the planar karst development section, karst development degree and karst development depth, and obtain geophysical information.

[0045] Preferably, on the basis of the preliminary division of the karst development degree of the bridge site area, combined with the results of geophysical exploration, further comprehensive determination is made to divide the karst development degree zones of the bridge site area.

[0046] Preferably, a BIM three-dimensional model of the karst area is established based on the results of geological mapping and geophysical interpretation, and a three-dimensional visual fusion display is performed to facilitate the subsequent survey of the karst area, which is more intuitive and convenient for recording and simulating the degree of karst development in the karst area.

[0047] Specifically, when the karst development degree zoning includes a strongly karst development area, the strongly karst development area is verified, and the verification method includes:

[0048] A plurality of verification holes are arranged in the area with intense karst development. If at least one of the verification holes reveals that the karst development degree is intense and the verification result is accurate, the design position of the pier and the hole span are adjusted. If all the verification holes reveal that the karst development degree is not intense, the verification result is judged to be inaccurate, and the area with intense karst development is downgraded to an area with moderate karst development.

[0049] Preferably, when the cave height detected in the verification hole is >3m, or the linear karst rate is >10, or the cave visibility rate is >60%, it is judged that karst is strongly developed; when the cave height detected in the verification hole is <3m, the linear karst rate is <10, and the cave visibility rate is <60%, it is judged that karst is not strongly developed.

[0050] As one of the specific implementation methods, for piers identified as areas with intense karst development, a verification hole is arranged under the central foundation pile, and four verification holes are arranged diagonally. Verification is carried out through the verification holes to confirm the degree of karst development.

[0051] In the optimized implementation mode, in step S300, the drilling of the preset position of the pier is carried out, and the drilling of the pier in the weakly developed karst area includes the following steps:

[0052] Several preliminary exploration holes are set at the pier layout locations in the weakly developed karst area, and the holes are drilled to a depth of not less than 15m from the intact weakly weathered bedrock and 10 to 15m below the pile end.

[0053] As one of the specific real-time methods, two preliminary exploration holes (i.e. corner exploration holes) are arranged under the diagonal foundation piles of each pier. If the preliminary exploration holes reveal that karst is not developed, that is, there are no caves and dissolution cracks, the drilling is carried out to the complete weakly weathered bedrock of not less than 15m, and it meets the requirement of 10-15m below the pile end. If the preliminary exploration holes reveal soluble rock, the karst rate and cave rate of the two preliminary exploration holes are calculated. If the two preliminary exploration holes reveal that at least one karst is weakly developed, a central drilling hole is further arranged at the pier, as shown in the attached manual. Figure 2 and 3 As shown, the drilling depth is no less than 15m to the intact weakly weathered bedrock and 10-15m below the pile end. If each preliminary exploration hole reveals at least one moderately developed karst, drilling is performed pile by pile, as shown in the attached manual. Figure 6 As shown, the drilling depth to the complete weathered bedrock is not less than 15m, and it passes through 15m below the bottom plate of the adjacent borehole cave, and at the same time, it must meet the requirement of 10 to 15m below the pile end.

[0054] In the optimized implementation mode, in step S300, the drilling of the preset position of the pier is carried out, and the drilling of the pier in the medium karst development area includes the following steps:

[0055] Several preliminary exploration holes are set at the pier layout location in the moderately developed karst area, and drilled to a depth of not less than 20m of intact weakly weathered bedrock and 10 to 15m below the pile end.

[0056] As one of the specific implementation methods, a preliminary exploration hole is arranged under the central foundation pile of the pier. If the preliminary exploration hole reveals soluble rock, two corner exploration holes are further arranged diagonally at the pier. If both the preliminary exploration hole and the corner exploration hole reveal that karst is not developed, the two corner exploration holes are drilled to a weak weathering of intact bedrock of not less than 15m and 10 to 15m below the pile end. If the preliminary exploration hole and the corner exploration hole reveal that karst is developed, the karst rate and cave rate of the preliminary exploration hole and the corner exploration hole line are calculated. If all holes reveal that karst is weakly developed, a central borehole is further arranged at the pier, as shown in the attached manual. Figure 4 and 5 As shown, the drilling hole is not less than 15m to the complete weakly weathered bedrock, and 10 to 15m below the pile end. If each hole reveals that at least one hole is moderately developed karst, then drill each pile, drilling to the complete weakly weathered bedrock is not less than 15m, and passing through the bottom plate of the adjacent borehole karst cave 15m below, and at the same time, it must meet the requirement of 10 to 15m below the pile end.

[0057] The optimized implementation method, specifically, step S400 is, according to the initially determined bridge pier layout position, combined with the karst development degree in the previous exploration process, to carry out pier drilling in the karst area of ​​the bridge project, to classify the karst development degree of the pier, and to optimize the pier position and span according to the classification results. The pier should avoid the area with strong karst development and its influence area.

[0058] Preferably, the drilling equipment of the present invention is equipped with intelligent sensing equipment, which can obtain parameters such as drilling speed and torque, changes in drilling fluid density and viscosity, changes in gas measurement components, DCS index, turntable speed, etc. during the drilling process, and use the karst drilling sample library to integrate intelligent algorithms to comprehensively judge the karst development situation.

[0059] Preferably, the drilling process of the present invention preferably uses a survey while drilling device, which is provided with a sensor and an image acquisition unit, and can obtain karst data and images in the hole during the drilling process. After background data analysis, the degree of karst development can be directly determined, which is convenient and fast, and improves drilling efficiency.

[0060] Those skilled in the art will appreciate that the present invention can be implemented in many other specific forms without departing from the spirit and scope of the present invention. Although embodiments of the present invention have been described, it should be understood that the present invention should not be limited to this embodiment, and those skilled in the art can make changes and modifications within the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A dynamic control method for railway bridge engineering survey in karst areas, characterized in that: The following steps are involved: S100: Preliminary acquisition of the karst distribution range in the bridge site area; S200: Acquire karst development information, wherein the karst development information includes planar karst development sections, karst development degree and karst development depth; S300: Determine the preset positions of each pier according to the karst development information obtained in step S200, and perform drilling at the determined preset positions of the piers; S400: judging whether the preset positions of the piers are suitable according to the drilling results of step S300, and if suitable, determining the preset positions of the piers as the pier construction positions; if not suitable, adjusting the preset positions of the piers.

2. The dynamic control method for surveying railway bridge engineering in karst areas according to claim 1 is characterized in that: The step S200 includes: obtaining prediction information and geophysical interpretation result information, and obtaining the karst development information through comprehensive determination of the prediction information and the geophysical interpretation result information.

3. The dynamic control method for surveying railway bridge engineering in karst areas according to claim 2 is characterized in that: The acquisition of the prediction information includes: according to the initially acquired karst distribution range of the bridge site area, dividing the karst development degree of the bridge site area according to the surface karst development density, and acquiring the prediction information.

4. The dynamic control method for karst area railway bridge engineering survey according to claim 2 is characterized in that: The acquisition of the geophysical interpretation results information includes: setting a number of parallel geophysical exploration lines along the longitudinal direction of the bridge to be built, conducting karst geophysical exploration, and obtaining geophysical information on karst distribution in the bridge site area.

5. The method for dynamic control of railway bridge engineering survey in karst areas according to claim 1 is characterized in that: The step S300 specifically includes: The bridge site is zoned according to the karst development degree based on the karst development information. The karst development degree includes an area with strong karst development, an area with medium karst development and an area with weak karst development. The preset position of the pier is determined based on the karst development degree zoning result, wherein the preset position of the pier avoids the area with strong karst development.

6. The dynamic control method for karst area railway bridge engineering survey according to claim 5 is characterized in that: The step S300 further comprises: When the karst development degree zoning includes a strongly karst development area, the strongly karst development area is verified, and the verification method includes: A plurality of verification holes are arranged in the area where karst is strongly developed. If at least one of the verification holes reveals that the degree of karst development is strongly developed, the verification result is accurate. If all the verification holes reveal that the degree of karst development is not strongly developed, the verification result is judged to be inaccurate, and the area where karst is strongly developed is downgraded to an area where karst is moderately developed.

7. The method for dynamic control of railway bridge engineering survey in karst areas according to claim 6 is characterized in that: The arrangement of the verification holes includes: arranging one verification hole under the central foundation pile and arranging four verification holes diagonally, and verifying through the verification holes to calibrate the degree of karst development.

8. The method for dynamic control of railway bridge engineering survey in karst areas according to claim 5 is characterized in that: The drilling of the preset position of the pier in the weakly developed karst area includes: setting a number of preliminary exploration holes at the pier layout position in the weakly developed karst area, drilling to the intact bedrock with weak weathering of not less than 15m and 10 to 15m below the pile end.

9. The method for dynamic control of railway bridge engineering survey in karst areas according to claim 5, characterized in that: The drilling of the preset position of the pier in the medium-developed karst area includes: setting a number of preliminary exploration holes at the pier layout position in the medium-developed karst area, drilling to the intact bedrock with weak weathering of not less than 20m and 10 to 15m below the pile end.

10. The method for dynamic control of railway bridge engineering survey in karst areas according to claim 9, characterized in that: If the aforementioned preliminary exploration holes reveal soluble rock, two corner exploration holes shall be arranged diagonally on the pier, and the corner exploration holes shall be drilled to a depth of not less than 15m from the intact weakly weathered bedrock and 10 to 15m below the pile end.

Images