CN104676110A - On-site overhanging protection method of high-voltage cable bailey truss under condition of excavation of foundation pit - Google Patents

Abstract

The invention discloses an in-situ suspension protection method of a high-voltage cable bailey frame under the excavation condition of a foundation pit, relates to the technical field of construction, and comprises the following steps: (1) the anchorage section of the bailey frame column, (2) erecting the bailey frame structure, (3) partial excavation under the cable, (4) forming a suspension system, (5) suspending the cable, (6) removing the original cable trench, (7) excavating the foundation pit, (8) building a new cable trench, Remove the suspension system, all the suspension protection systems for high-voltage cables described in the present invention must be completed before the excavation of the foundation pit at the corresponding position. During the construction of the suspension protection system for high-voltage cables, relevant personnel from the electric power department are also invited to supervise and guide on-site At the same time, cooperate with the power department to implement outsourcing protection of cables and cable joints, which fully guarantees construction safety.

Description

A protection method for in-situ suspension of high-voltage cable bailey under the condition of foundation pit excavation

technical field

The invention relates to the field of construction technology, and more specifically, the invention relates to a method for in-situ suspension protection of a high-voltage cable bailey under the condition of foundation pit excavation.

Background technique

The foundation pit is the earth pit excavated at the foundation design position according to the base elevation and foundation plane size. Before excavation, the excavation plan should be determined according to the geological and hydrological data, combined with the conditions of the nearby buildings, and the waterproof and drainage work should be done well. If the excavation is not deep, the side slope can be used to stabilize the soil slope, and the slope size is determined according to the relevant construction regulations. For those with deep excavation and nearby buildings, the foundation pit wall support method, shotcrete retaining wall method, and large foundation pit even adopt methods such as underground diaphragm wall and column-type bored pile interlocking to prevent the outer soil layer from collapsing. .

During construction, according to the site conditions and clarification from the power department, the high-voltage cables in the original site cannot be moved outside the foundation pit. Under such circumstances, the power department often requires that the high-voltage cables must be protected in situ during the construction of the foundation pit, and the cables will be relocated to new cable trenches after the permanent structure is completed. In such cases, the currently commonly used protection method for high-voltage cables is to build a partition wall protection method. This method is time-consuming, laborious, costly, and takes up a lot of space, which hinders construction.

Contents of the invention

The problem to be solved by the present invention is to provide a method for in-situ suspension protection of high-voltage cable baileys under the excavation of foundation pits, so as to solve the defects of time-consuming, labor-intensive, high cost and large space occupation of existing methods.

In order to achieve the above object, the technical solution adopted by the present invention is: 1. A method for in-situ suspension protection of high-voltage cable bailey under the condition of foundation pit excavation, which is characterized in that it includes the following steps:

(1) The anchorage section of the column of the Bailey frame: firstly, construct the artificial excavated piles according to the coordinates on the original ground of the foundation pit, and the artificial excavated piles with a cross-section of φ1200mm at the anchorage end of the columns to the bottom of the foundation pit, and merge them into the strong weathered rock 5m or moderately weathered 3m or slightly weathered 2m end hole, and then bury the Bailey frame column on the top of the pile;

(2) Set up the Bailey frame structure: bury 2 I 50b I-beams on the top of the pile, and erect 2 I 50b I-beams, 40b# I-beam main beam and 14# channel steel, 40b# I-beam The main beam is bolted to two I 50b I-beam beams, and the Bailey frame main beam, Bailey frame secondary beam, and Bailey frame purlins are erected;

(3) Partial excavation under the cable: excavate partly directly under the channel steel to the bottom of the pipeline trough, dig out soil under the pipeline trough to make a hole, and insert the 14# channel steel supporting pipeline trough in time;

(4) Form a suspension system: use 20 round steel to connect the bracket with the channel steel on the I-beam main beam, and tighten the two ends with screws to form a suspension system;

(5) Suspension cables: excavate shallowly to the bottom of the pipeline, manually remove the partitions and side plates in the cable trench, and timely penetrate the longitudinal angle steel, wooden boards, etc. to support the corresponding positions of the partitions in the cable trench, manually remove them, and penetrate the horizontal angle steel , longitudinal angle steel, planks, etc. to support the cables. All steel structures must have reliable grounding, grounding resistance ≤ 1 ohm;

(6) Remove the original cable trough: the original cable trough can only be removed after the construction of the suspension system is completed. It must be removed manually within 2m from the cable, and mechanical removal is strictly prohibited;

(7) Excavation of the foundation pit: Continue to excavate the earth in layers to the bottom of the foundation pit, construct the basement structure to the ground, and reserve holes at the positions of the steel columns. In order to ensure the stability of the column and reduce the influence of the lateral pressure of the earthwork on the stability of the column, the excavation of the earthwork must be excavated in layers, and each section is excavated in layers at a depth of 1.5 meters. The surface must be cut into a 45° inclined surface with an excavator to ensure the stability of the soil at the joint surface of the section;

(8) Build a new cable trench and remove the suspension system: Lay a new pipe trench at the original site of the cable, remove the steel beams of the suspension system, and pour reserved holes.

Preferably, the section of the Bailey frame column in the described step (1) is 2 I 50b I-beams, which are buried at the top of the anchoring end.

Preferably, the main girder of the Bailey frame in the described step (2) is two I 50b I-beams that are horizontally erected on the top of the column of the Bailey frame.

Preferably, the Bailey secondary beam in the step (2) is two 40b# I-beams, the beam top elevation is -0.17m, the distance between the two I-beams is 2.5-4m, and the span is 8.5-10m.

Preferably, the Bailey frame purlin in the step (2) is a 14# channel steel laid on two I-beam secondary beams, and correspondingly the cable bottom directly below the channel steel passes through a 14# channel steel.

Preferably, in said step (5), two 14# channel steels are connected by Φ20 round steel to form a suspension system, so as to suspend the cable, and the longitudinal spacing of the channel steels is 2.5～4m; Lay 4cm thick wooden planks, the two sides of the plank are laid on the L50×5 angle steel, and the angle steel is laid longitudinally on the channel steel along the direction of the pipeline.

Beneficial effects: under the condition of foundation pit excavation, the method for in-situ suspension protection of high-voltage cable bailey frame under the condition of foundation pit excavation is 17.5m, and the length of the high-voltage cable to be protected in the foundation pit reaches 84m. In order to ensure the safety of high-voltage cables, the suspension protection scheme of Bailey frame across the foundation pit is adopted to protect the high-voltage cables. All the suspension protection systems of high-voltage cables in this protection method must be excavated in the foundation pit at the corresponding position During the construction of the high-voltage cable suspension protection system, relevant personnel from the power department were invited to supervise and guide on-site, and at the same time cooperated with the power department to implement outsourced protection of cables and cable joints, which fully guaranteed construction safety. The protection method saves time and labor, has low cost, occupies a small area, and does not interfere with construction.

Detailed ways

Example 1:

The method is carried out in eight steps. First, (1) the anchorage section of the column of the Bailey frame: firstly, the artificial excavated pile is constructed on the original ground of the foundation pit according to the coordinate position, and the artificial excavated pile with the cross section of the anchorage end of the column is φ1200mm to the bottom of the foundation pit. Merge into the 5m end hole of strong weathered rock, and then bury the Bailey frame column on the pile top; (2) Build the Bailey frame structure: bury 2 I 50b I-beams on the pile top, and erect 2 I 50b I-beam beams , 40b# I-beam main beam and 14# channel steel, 40b# I-beam main beam is connected with two I 50b I-beam beam bolts, and the Bailey frame main beam, Bailey frame beam, and Bailey frame purlin are set up. The main girder of the Bailey frame is two I50b I-beams horizontally erected on the top of the column of the Bailey frame, and the secondary beam of the Bailey frame is two 40b# I-beams. The elevation of the beam top is -0.17m, and the distance between the two I-beams is 2.5m, with a span of 8.5m, the Bailey frame purlin is 14# channel steel laid on two I-steel secondary beams, and correspondingly passes through a 14# channel steel at the bottom of the cable directly below the channel steel; then Carry out (3) partial excavation under the cable: excavate partly directly under the channel steel to the bottom of the pipeline trough in sections, dig out soil under the pipeline trough to make a hole, and insert the 14# channel steel supporting pipeline trough in time; then carry out (4 ) to form a suspension system: use 20 round steel to connect the bracket with the channel steel on the I-beam main beam, tighten the two ends with screws to form a suspension system; then carry out (5) suspension cables: shallow excavation to At the bottom of the pipeline, while manually removing the partitions and side plates in the cable trench, penetrate the longitudinal angle steel, wooden boards, etc. to support the corresponding positions of the partitions in the cable trench, manually remove them, and penetrate the horizontal angle steel, longitudinal angle steel, wooden boards, etc. to support the cables. All steel structures must have reliable grounding, ground resistance ≤ 1 ohm; then proceed to (6) Remove the original cable duct: the original cable duct can only be removed after the construction of the suspension system is completed, and must be used within 2m from the cable Manual demolition, mechanical demolition is strictly prohibited; then (7) Excavation of the foundation pit: Continue to excavate the earth in layers to the bottom of the foundation pit, construct the basement structure to the ground, and reserve holes at the steel structure columns. In order to ensure the stability of the column and reduce the influence of the lateral pressure of the earthwork on the stability of the column, the excavation of the earthwork must be excavated in layers, and each section is excavated in layers at a depth of 1.5 meters. The surface must be cut into a 45° inclined surface with an excavator to ensure the stability of the soil at the joint surface of the section; finally (8) build a new cable trench and remove the suspension system: lay a new pipe groove at the original site of the cable, and remove the suspension system For steel beams, holes are reserved for pouring.

Example 2:

Repeat embodiment 1 by the same steps as described, the difference is: step (1) Bailey frame column anchor section: merge into the middle weathered rock 3m end hole, then bury the Bailey frame column at the pile top, step (2) ) to erect the Bailey frame structure: the Bailey frame beam is two 40b# I-beams, the beam top elevation is -0.17m, the distance between the two I-beams is 3m, and the span is 9m.

Example 3:

Repeat embodiment 1 by the same steps as described, the difference is: step (1) Bailey frame column anchorage section: merge into the micro-weathered rock 2m end hole, then bury the Bailey frame column at the top of the pile, step (2) ) to erect the Bailey frame structure: the Bailey frame beam is two 40b# I-beams, the elevation of the beam top is -0.17m, the distance between the two I-beams is 4m, and the span is 10m.

The above is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process conversion made by using the content of the description of the present invention, or directly or indirectly used in other related technical fields, All are included in the scope of patent protection of the present invention in the same way.

Claims (6)

1. a high voltage cable Bailey bracket original place suspension protection method under excavation of foundation pit situation, is characterized in that, comprise the steps:

(1) Bailey bracket column anchoring section: first press coordinate position construction artificial digging pile at foundation ditch original ground, column anchored end cross section is that the artificial digging pile of φ 1200mm is at the bottom of foundation ditch, be incorporated to the whole hole of strong-weathered rock 5m or middle weathering 3m or gentle breeze 2m, then bury Bailey bracket column underground on stake top;

(2) Bailey bracket structure is set up: bury 2 I 50b I-steel underground on stake top, and set up 2 I 50b I-steel crossbeams, 40b# I-steel girder and 14# channel-section steels, 40b# I-steel girder is connected with 2 I 50b I-steel transom bolts, sets up Bailey bracket girder, Bailey bracket secondary beam, Bailey bracket purlin;

(3) local excavation under cable: segmentation is immediately below channel-section steel bottom local excavation to chase, and soil digging cavitation is got through below chase, and insert 14# channel-section steel support column wire casing in time;

(4) form Suspension System: adopt 20 round steel to be connect by the channel-section steel on bracket and I-steel girder, two ends screw tightens up, form Suspension System;

(5) pendant cables: be shallowly excavated at the bottom of pipeline, limit is manually abolished cable channel central diaphragm and side plate limit and is penetrated sole bar angle, plank etc. in time and hold cable channel central diaphragm corresponding position and manually abolish, and penetrates horizontal angle steel, sole bar angle, plank etc. and holds cable.All steel structure must have reliable ground connection, ground connection ground resistance≤1 ohm;

(6) remove original wire way: system construction to be suspended is complete can be removed former cable tube seat, manual type must be adopted to remove within the scope of distance cable 2m, forbid mechanical removal;

(7) excavation of foundation pit: continue at the bottom of the stage excavation earthwork to foundation ditch, construction basement structure to ground, at steel pile position reserving hole.For guaranteeing the stability of column, reducing the stability influence of earthwork side pressure column, the necessary sectional stage excavation of earth excavation, each section carries out stage excavation by 1.5 meters of degree of depth, each section must cut plane of inclination at 45 ° with excavator at interface, ensures the stability of the section interface soil body;

(8) newly-built cable channel, dismounting Suspension System: lay new tube seat in cable former address, and remove the section steel beam of Suspension System, build reserving hole.

2. according to high voltage cable Bailey bracket original place suspension protection method under a kind of excavation of foundation pit situation according to claim 1, it is characterized in that: the cross section of the Bailey bracket column in described step (1) is 2 I 50b I-steel, buries underground in anchored end top.

3. according to high voltage cable Bailey bracket original place suspension protection method under a kind of excavation of foundation pit situation according to claim 1, it is characterized in that: the Bailey bracket girder in described step (2) is two I 50b I-steel that Bailey bracket column top is laterally set up.

4. according to high voltage cable Bailey bracket original place suspension protection method under a kind of excavation of foundation pit situation according to claim 1; it is characterized in that: the Bailey bracket secondary beam in described step (2) is two 40b# I-steel; top surface of the beam absolute altitude is-0.17m; article two, I-steel spacing is 2.5 ~ 4m, and span is 8.5 ~ 10m.

5. according to high voltage cable Bailey bracket original place suspension protection method under a kind of excavation of foundation pit situation according to claim 1; it is characterized in that: the Bailey bracket purlin in described step (2) is the 14# channel-section steel be laid on two I-steel secondary beams, and through a 14# channel-section steel bottom cable accordingly immediately below this channel-section steel.

6. according to high voltage cable Bailey bracket original place suspension protection method under a kind of excavation of foundation pit situation according to claim 1, it is characterized in that: connect two 14# channel-section steels by Φ 20 round steel in described step (5) and form suspension system, with this pendant cables, channel-section steel longitudinal pitch be 2.5 ~ 4m not etc.; Close paving 4cm thick plank on the 14# channel-section steel of cable bottom, plank both sides ride on the angle steel of L50 × 5, and angle steel is longitudinally laid on channel-section steel along pipeline direction.