A method for determining a protection scheme for a high-voltage power box culvert near a deep foundation pit

Abstract

The application discloses a kind of high-voltage power box culvert protection scheme determination method of adjacent deep foundation pit, high-voltage power box culvert protection scheme is formulated by collecting construction site data, isolation pile and vibration isolation sand pile are formulated between underground station and high-voltage power box culvert, according to the stratum structure at the pre-protected power box culvert, vibration numerical simulation of construction scheme is carried out, and simulation vibration value atlas is generated;In pre-construction station, similar stratum is selected with pre-protected box culvert, and construction is carried out according to predetermined design scheme and is monitored, and similar stratum construction measured vibration value atlas is obtained;The vibration value of high-voltage power box culvert top and periphery is monitored under existing engineering environmental conditions to generate environmental measured vibration atlas;Simulated vibration value atlas, construction measured vibration value atlas and environmental measured vibration atlas are compared, when simulated vibration value atlas, construction measured vibration value atlas are all less than environmental measured vibration atlas, confirm that protection scheme is feasible.

Description

Technical Field

[0001] This invention relates to the field of municipal engineering technology, and in particular to a method for determining a protection scheme for a high-voltage power culvert adjacent to a deep foundation pit. Background Technology

[0002] The protection of buildings and the relocation of pipelines are common issues encountered during the construction of underground rail transit stations. The relocation and protection of power lines that affect the construction of underground rail transit stations need to be determined according to the specific circumstances. In particular, the relocation and protection of 110KV and 220KV high-voltage power lines are affected by many external factors. 110KV and 220KV high-voltage power lines are the main power supply lines of the area. If not handled carefully, they can cause large-scale power outages, which will have an adverse impact on residents, government offices, and enterprises.

[0003] Given the importance of protecting high-voltage cable pipelines, the protection scheme for high-voltage power culverts that are difficult to relocate or located near underground rail transit stations, as well as the impact of nearby construction, should be considered holistically. In older high-voltage power culverts, cable joints inevitably exhibit localized loosening and vibration sensitivity. If subjected to significant external vibrations, the risk of these high-voltage cable joints becoming detached is substantial, placing high demands on the construction of underground rail transit stations located near high-voltage power culverts. Determining the effectiveness of the protection scheme is a crucial issue that both the construction and design teams must address. Summary of the Invention

[0004] The purpose of this invention is to provide a method for determining the protection scheme of high-voltage power box culverts near deep foundation pits. The feasibility of the protection scheme for high-voltage power box culverts is determined by comparing simulated vibration value spectrum, actual construction vibration value spectrum and actual environmental vibration value spectrum, so as to protect high-voltage cable pipelines.

[0005] To achieve the above objectives, the present invention provides a method for determining a protection scheme for a high-voltage power culvert adjacent to a deep foundation pit, comprising the following steps:

[0006] S1. Data collection and scheme formulation: Collect data on high-voltage power box culverts, on-site hydrogeological data, and on-site spatial location data, and propose a protection scheme for high-voltage power box culverts based on the collected data, and formulate construction data for isolation piles and vibration isolation sand piles;

[0007] S2. Vibration numerical simulation: Based on the on-site engineering environment and geological composition, select the reinforcement hole depth of the isolation piles and vibration isolation sand piles, and the stratum parameters within the length range of the station retaining piles. Substitute them into the vibration simulation calculation model to obtain the vibration values ​​generated by the construction of isolation piles and vibration isolation sand piles, as well as the vibration values ​​of the station retaining piles after the isolation piles and vibration isolation sand piles are completed, and form a simulated vibration value spectrum.

[0008] S3. Vibration monitoring in similar geological formations: Select a location far from the high-voltage power box culvert and with a geological composition similar to the construction site. Construct isolation piles, vibration isolation sand piles, and station retaining piles according to the proposed high-voltage power box culvert protection plan. The construction length should be no less than 10m. Measure the construction vibration values ​​of the isolation piles and vibration isolation sand piles, and record the vibration values ​​generated during the construction of the station retaining piles. Compile the above measured vibration values ​​into a construction measured vibration value spectrum.

[0009] S4. On-site road condition vibration monitoring: Monitor the range of vibration values ​​generated by road traffic under on-site engineering environmental conditions, set up vibration monitoring points along the road surface in the direction of high-voltage power box culvert, record the vibration values ​​generated by ground traffic at different time periods, and compile them into an environmental measured vibration value spectrum.

[0010] S5. Numerical comparison and scheme determination: Compare the simulated vibration value spectrum, the environmental measured vibration value spectrum, and the construction measured vibration value spectrum. When both the simulated vibration value spectrum and the construction measured vibration value spectrum are less than the environmental measured vibration value spectrum, it is determined that the implementation of the high-voltage power box culvert protection scheme meets the protection requirements for the safety of high-voltage cable pipelines, and the feasibility of the scheme is confirmed.

[0011] The preferred high-voltage power culvert protection scheme in S1 is as follows:

[0012] A single row of isolation piles and a double row of vibration-damping sand piles are arranged between the station retaining piles and the high-voltage power box culvert. Both the isolation piles and the vibration-damping sand piles are set in the original stratum and located below the existing road surface. The isolation piles are close to the station retaining piles. The isolation piles consist of an inner steel pipe and an outer steel pipe arranged coaxially. A locator is set between the outer steel pipe and the inner steel pipe. Several grouting holes are set on the pipe wall of the inner steel pipe. The vibration-damping sand piles are close to the high-voltage power box culvert and are filled with yellow sand.

[0013] Preferably, during the construction of isolation piles and vibration isolation sand piles, the high-voltage power box culvert is subjected to automated vibration monitoring. If any abnormality is detected during construction, work is stopped in time to protect the safe operation of the high-voltage cable pipeline in the high-voltage power box culvert.

[0014] Therefore, this invention employs a method for determining a protection scheme for high-voltage power culverts near deep foundation pits using the aforementioned structure. The installation of vibration-isolating sand piles effectively reduces the propagation of vibration waves, allowing the energy of the vibration waves to decay and be released rapidly. This reduces the impact of rotary drilling rigs on the power trench during the construction of station retaining piles, further enhancing the protective effect of the isolation piles on the high-voltage power culvert. Based on a comparison of simulated vibration value spectra, environmentally measured vibration value spectra, and construction-measured vibration value spectra, a scientifically accurate judgment is formed, enhancing the safety and reliability of the construction scheme and reducing the impact of construction vibration on the high-voltage power culvert.

[0015] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating an embodiment of the method for determining a protection scheme for a high-voltage power box culvert near a deep foundation pit according to the present invention.

[0017] Figure 2 This is a schematic diagram showing the positional relationship between the station enclosure structure and the high-voltage power box culvert according to an embodiment of the present invention;

[0018] Figure 3 This is a cross-sectional schematic diagram of the high-voltage power box culvert protection scheme according to an embodiment of the present invention;

[0019] Figure 4 This is a schematic plan view of the high-voltage power box culvert protection scheme according to an embodiment of the present invention;

[0020] Figure 5 This is a schematic diagram of the isolation pile structure according to an embodiment of the present invention;

[0021] Figure 6 Embodiments of the present invention Figure 5 Schematic diagram of the AA section structure.

[0022] Figure Labels

[0023] 1. Original strata; 2. Existing road surface; 3. Power box culvert; 4. Station retaining piles; 5. Outer steel pipe; 6. Vibration isolation sand piles; 7. Inner steel pipe; 8. Positioner. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Example

[0026] As shown in the figure, the Yanshan Interchange East Station of Jinan Metro Line 4 is located east of the Yanshan Interchange—on the northeast side of the intersection of Jingshi Road and East Second Ring Road. It runs east-west, is 197 meters long, and is a three-level underground island platform station. The station occupies part of the auxiliary road of Jingshi Road on its south side.

[0027] After on-site verification, the existing power cable trench (2000×2100 mm) is laid parallel to the station in an east-west direction. The net distance between the bored piles at the east and west ends has increased to 1.75 meters, and the net distance in the middle section is 3.55 meters. It is approximately 1.4–1.6 meters below the ground surface, with a trench bottom burial depth of 4 meters, and is arranged in an east-west direction. The power cable trench is a brick structure and contains two existing 110kV lines and 26 10kV cables, making it one of the main power supply lines in Jinan City.

[0028] According to geological survey data, the strata within the proposed reinforcement area of ​​the power cable trench consist of plain fill, miscellaneous fill (including boulders), residual soil, gravel, fault breccia with mud and breccia, and completely weathered, strongly weathered and moderately weathered diorite; the stable groundwater level is buried at a depth of 10.4 to 15.7 m, and there is no groundwater within the reinforcement area of ​​the high-voltage power box culvert 3.

[0029] According to the survey of the retaining structure and surrounding pipelines of the underground station of the rail transit, it has been verified that the high-voltage power box culvert 3 is a brick structure with a concrete slab on top; the minimum distance between the outer side of the high-voltage power box culvert 3 and the outer side of the retaining pile at the end of the station is 1.75m, and the distance at other locations is 3.55m.

[0030] Based on the engineering hydrogeological conditions, single-row Φ159@350mm seamless steel pipe micro-isolation piles and double-row Φ150@350mm vibration-damping sand piles 6 were used to reinforce the relationship between the high-voltage power box culvert 3 and the station retaining structure. The isolation piles and vibration-damping sand piles 6 were all buried in the original stratum 1, located below the existing road surface 2.

[0031] The high-voltage power box culvert 3 is located within the power cable trench. First, a row of miniature isolation piles is constructed 200mm outside the station retaining piles 4. Each isolation pile consists of an outer steel pipe 5 and an inner steel pipe 7 arranged coaxially, with a Φ108 inner steel pipe 7 embedded within the outer steel pipe 5. Several grouting holes are provided on the wall of the inner steel pipe 7. Positioners 8 are staggered between the inner steel pipe 7 and the isolation piles at 2m intervals to ensure the coaxiality of the inner and outer steel pipes. After the isolation piles are constructed, cement grout is injected into the inner steel pipe 7. The isolation piles isolate the construction area of ​​the station retaining piles 4 from the high-voltage power box culvert 3, reducing the impact of rotary drilling on the power cable trench. Secondly, they reduce borehole wall collapse and lateral deformation during rotary drilling, avoiding adverse effects on the adjacent power cable trench caused by deformation after borehole wall collapse.

[0032] After the cement grout strength of the isolation piles reaches 75%, two rows of vibration-damping sand piles 6 are constructed between the isolation piles and the high-voltage power culvert 3. The vibration-damping sand piles 6 are spaced 320mm apart from the isolation piles, and the two rows of vibration-damping sand piles 6 are also spaced 320mm apart. The vibration-damping sand piles 6 are arranged in a quincunx pattern, and the central hole is backfilled with yellow sand. The vibration-damping sand piles 6 can effectively reduce the propagation of vibration waves, allowing the energy of the vibration waves to decay and be released rapidly, thus reducing the impact of rotary drilling rig construction on the power cable trench.

[0033] To ensure that the vibration generated by the construction plan is less than the vibration value borne by the high-voltage cable pipeline joint, based on the site engineering environment and geological composition, the stratum parameters within the range of the steel pipe pile reinforcement hole depth and the length of the station retaining pile 4 were selected and substituted into the vibration simulation calculation model to obtain the vibration values ​​generated by the construction of steel pipe piles and retaining piles, as well as the vibration values ​​of the station retaining pile 4 after the construction of isolation piles and vibration isolation sand piles 6, and to create a simulated vibration value spectrum.

[0034] While conducting vibration numerical simulation of the design scheme, the range of vibration values ​​generated by road traffic under the on-site engineering environment was monitored. Vibration monitoring points were set up along the road surface in the 3rd direction of the high-voltage power box culvert, and the vibration values ​​generated by ground traffic at different time periods were recorded and compiled into an environmental measured vibration value spectrum.

[0035] In the construction area of ​​the retaining piles on the north side of the station, steel pipe piles, vibration-damping sand piles 6, and retaining piles were constructed according to the design plan. The vibration values ​​of the steel pipe piles and vibration-damping sand piles 6 were measured, and the length of the steel pipe piles and vibration-damping sand piles 6 was no less than 10m according to the design plan. The station retaining piles 4 were constructed, and the vibration values ​​generated by the construction of the retaining piles in different strata were recorded. The measured vibration values ​​were compiled into a construction measured vibration value spectrum.

[0036] The measured vibration values ​​in the environment, the simulated vibration values, and the measured vibration values ​​during construction were compared. The simulated vibration values ​​and the measured vibration values ​​during construction were all lower than the measured vibration values ​​in the environment, confirming the feasibility of the scheme. It was determined that the implementation of the high-voltage power culvert protection scheme met the safety protection requirements for high-voltage cable pipelines.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for determining a protection scheme for a high-voltage power culvert adjacent to a deep foundation pit, characterized in that, The steps are as follows: S1. Data collection and scheme formulation: Collect data on high-voltage power box culverts, on-site hydrogeological data, and on-site spatial location data, and propose a protection scheme for high-voltage power box culverts based on the collected data, and formulate construction data for isolation piles and vibration isolation sand piles; S2. Vibration numerical simulation: Based on the on-site engineering environment and geological composition, select the reinforcement hole depth of the isolation piles and vibration isolation sand piles, and the stratum parameters within the length range of the station retaining piles. Substitute them into the vibration simulation calculation model to obtain the vibration values ​​generated by the construction of isolation piles and vibration isolation sand piles, as well as the vibration values ​​of the station retaining piles after the isolation piles and vibration isolation sand piles are completed, and form a simulated vibration value spectrum. S3. Vibration monitoring in similar geological formations: Select a location far from the high-voltage power box culvert and with a geological composition similar to the construction site. Construct isolation piles, vibration isolation sand piles, and station retaining piles according to the proposed high-voltage power box culvert protection plan. The construction length should be no less than 10m. Measure the construction vibration values ​​of the isolation piles and vibration isolation sand piles, and record the vibration values ​​generated during the construction of the station retaining piles. Compile the above measured vibration values ​​into a construction measured vibration value spectrum. S4. On-site road condition vibration monitoring: Monitor the range of vibration values ​​generated by road traffic under on-site engineering environmental conditions, set up vibration monitoring points along the road surface in the direction of high-voltage power box culvert, record the vibration values ​​generated by ground traffic at different time periods, and compile them into an environmental measured vibration value spectrum. S5. Numerical comparison and scheme determination: Compare the simulated vibration value spectrum, the environmental measured vibration value spectrum, and the construction measured vibration value spectrum. When both the simulated vibration value spectrum and the construction measured vibration value spectrum are less than the environmental measured vibration value spectrum, it is determined that the implementation of the high-voltage power box culvert protection scheme meets the protection requirements for the safety of high-voltage cable pipelines, and the feasibility of the scheme is confirmed.

2. The method for determining a protection scheme for a high-voltage power culvert adjacent to a deep foundation pit according to claim 1, characterized in that, The high-voltage power box culvert protection scheme in S1 is as follows: A single row of isolation piles and a double row of vibration-damping sand piles are arranged between the station retaining piles and the high-voltage power box culvert. Both the isolation piles and the vibration-damping sand piles are set in the original stratum and located below the existing road surface. The isolation piles are close to the station retaining piles. The isolation piles consist of an inner steel pipe and an outer steel pipe arranged coaxially. A locator is set between the outer steel pipe and the inner steel pipe. Several grouting holes are set on the pipe wall of the inner steel pipe. The vibration-damping sand piles are close to the high-voltage power box culvert and are filled with yellow sand.

3. The method for determining a protection scheme for a high-voltage power culvert adjacent to a deep foundation pit according to claim 1, characterized in that: During the construction of isolation piles and vibration isolation sand piles, the high-voltage power box culvert is subjected to automated vibration monitoring. If any abnormality is detected during construction, work is stopped in time to protect the safe operation of the high-voltage cable pipeline in the high-voltage power box culvert.

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