Methods for preventing collapse of bridge abutments by backfilling with sand.

Abstract

This invention discloses a method for preventing collapse of backfill sand on the abutment backfill of a reconstructed or expanded bridge abutment, comprising the following steps: 1) fabricating supporting steel plates and fixing them to the abutment backfill side; 2) drilling grouting holes and inserting grouting pipes; 3) completely sealing the outer side of the already open half of the abutment with cement mortar; 4) grouting each grouting pipe one by one; and 5) completing the backfill sand backfill anti-collapse treatment for the other half of the abutment. This invention significantly reduces construction costs, effectively prevents backfill sand collapse, significantly improves construction efficiency and quality, and enhances road surface smoothness and vehicle safety.

Description

Technical Field

[0001] This invention relates to a highway bridge abutment reconstruction and expansion project, and more particularly to a method for treating the collapse of backfill sand behind the abutment during reconstruction and expansion, belonging to the field of bridge construction technology. Background Technology

[0002] With the continuous increase in traffic flow on highways and other types of roads, the number of road widening and reconstruction projects is increasing. Due to the immense traffic pressure, full closure for construction is not feasible, so a half-width construction and half-width maintenance approach is adopted. Existing bridge abutments have no side walls on the median strip side, and the half-width abutment connects seamlessly with the adjacent back wall, ensuring the backfill sand on the abutment side does not collapse. However, the currently common approach of opening the road to traffic immediately after half-width abutment construction, while ensuring uninterrupted traffic during reconstruction and expansion projects, inevitably leads to the collapse of the backfill sand on the already-open side of the abutment. The conventional method is to drive steel sheet piles to form a retaining wall for backfilling, but steel sheet pile backfilling has the following drawbacks:

[0003] 1. It cannot be in complete contact with the back wall, leaving a gap between them. The backfill sand will leak from the gap, causing the backfill sand on the back of the abutment to collapse.

[0004] Second, the gaps between the steel sheet pile sections cannot be completely eliminated, and the backfill sand will also leak from the gaps, which will also cause the backfill sand on the abutment to collapse.

[0005] Third, the cost of steel sheet piles and the cost of pile driving are both very high.

[0006] Currently, in the construction of bridge abutment reconstruction and expansion projects, the conventional treatment method after abutment backfill collapse is as follows: The collapsed area is backfilled simultaneously with the abutment backfill after half of the abutment construction is completed. However, because the collapse is located under the approach slab, the loose backfill sand cannot be compacted. Under the heavy traffic load on the road, the pavement behind the abutment is prone to collapse and become uneven, causing vehicles to bounce and endangering traffic safety. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preventing collapse of bridge abutments by backfilling sand behind them, thereby improving the quality of traffic flow for the reconstructed and expanded bridge abutments.

[0008] This invention is achieved through the following technical solution:

[0009] A method for preventing collapse of bridge abutments by backfilling sand behind them, comprising the following steps:

[0010] 1) Process and manufacture a support steel plate, wherein one side of the support steel plate is vertical and the other side is inclined, and the inclined side matches the shape of the side of the cap beam and the back wall and the side of the corbel that extend vertically upward from one side of the cap beam.

[0011] 2) After the reconstruction and expansion of half of the bridge abutment is completed but before backfilling with sand in layers, drill holes at intervals of 50-80cm between the upper and lower sides of the back wall edge and insert plain round steel bars. Then, the inclined side of the supporting steel plate is placed against the cap beam, back wall and corbel on the side facing the support plate, i.e., the back side of the abutment, and is located behind several plain round steel bars. Weld the inclined side of the supporting steel plate to the plain round steel bars to fix the supporting steel plate, so that the supporting steel plate is fixed on the back side of the abutment and the top of the supporting steel plate is located under the approach plate.

[0012] 3) Fill the backfill sand on the side of the abutment in layers and compact it. Manually clean up the debris near the abutment of the central divider to prevent construction machinery from damaging the steel support plate. Stack coarse sand on top of the support plate to press down on the support plate and prevent its bottom from deforming.

[0013] 4) At the junction of the slab and the central divider, in the loose backfill sand area under the slab, in the voids and uncompacted areas, and on one longitudinal side of the slab, drill a row of multiple grouting holes at even intervals; use solid-walled PVC pipes for grouting, and reserve 15-20mm grout outlet holes at a distance of H1 = 400-600mm from the top of the grouting pipe. Remove debris from the grouting holes before grouting; then press the grouting pipes into the grouting holes respectively.

[0014] 5) Since half of the bridge abutment has been opened to traffic, its side is exposed. In order to prevent the grouting pressure from dissipating, cement mortar is used to completely seal the side to prevent cement grout from leaking out.

[0015] 6) After the side sealing cement grout has completely hardened, the cement grout prepared by the forced mixer is injected into each grouting pipe one by one through a hydraulic press or grouting machine; when the cement grout overflows from the side sealing or the grouting pipe is full and can no longer be injected, stop grouting, seal the grouting pipe opening with a rubber plug to prevent grout leakage, and then proceed to the next grouting pipe; repeat this process to complete the grouting of each grouting pipe one by one; after the cement grout in the grouting pipe has completely hardened, cut the grouting pipe flat so that the top surface of the grouting pipe and the hardened cement column inside is level with the ground, thus completing the backfill sand anti-collapse treatment of half of the bridge abutment;

[0016] 7) After the reconstruction and expansion of half of the bridge abutment is completed, repeat steps 1) to 6) to complete the backfilling of the abutment backfill sand to prevent collapse of the other half of the bridge abutment.

[0017] The objectives of this invention can also be further achieved through the following technical measures.

[0018] Furthermore, in step 2), the maximum gap between the supporting steel plate and the back of the platform is no more than 5mm. If the maximum gap is greater than 5mm, a rubber strip is inserted to seal it. The thickness of the supporting steel plate is 10-12mm, the height H2 of the supporting steel plate is the distance from the top surface of the corbel to the bottom surface of the cap beam, and the bottom width B = 1.5-2m.

[0019] Furthermore, in step 2), the diameter of the plain round steel bar is 8-10 mm, the implantation depth H2 = 810-820 mm, and H3 = exposed length 95 mm. ～ 105mm.

[0020] Furthermore, in step 4), the spacing between multiple grouting holes in a row is 1.9–2.1 m, and the angle between the drilling axis and the vertical line, i.e., the drilling angle α, is 15°. ～ 45°, with a drilling depth of 1 / 2 the height of the back wall.

[0021] Furthermore, the outer diameter of the grouting pipe in step 4) is The wall thickness is 5mm; the top of the grouting pipe is 45-55mm above the original ground surface.

[0022] Furthermore, in step 6), the pump pressure of the hydraulic press or grouting machine is 0.2-0.5 MPa, and the flow rate is 20-50 L / min.

[0023] The supporting steel plate of this invention completely seals the exposed surface of the completed half of the bridge abutment, effectively preventing backfill sand from flowing out from the bottom. This ensures that when the backfill sand on the completed side of the abutment is excavated, it will not leak or collapse. The grouting holes provided in this invention further compact and solidify the backfill sand, ensuring backfill quality. Compared with existing construction methods using sheet piles, this invention significantly reduces construction costs, effectively prevents backfill sand collapse, significantly improves construction efficiency and quality, enhances road surface smoothness, and improves vehicle safety.

[0024] The advantages and features of the present invention will be illustrated and explained by the following non-limiting description of preferred embodiments, which are given by way of example only with reference to the accompanying drawings. Attached Figure Description

[0025] Figure 1 This is a partial plan view of a bridge abutment backfilling sand anti-collapse treatment construction project.

[0026] Figure 2 yes Figure 1 AA section enlarged view;

[0027] Figure 3 yes Figure 1 Enlarged cross-sectional view of BB. Detailed Implementation

[0028] The invention will be further explained below with reference to the accompanying drawings and an embodiment of the reconstruction and expansion project of the Lalinhe (Jilin-Heilongjiang provincial border) to Harbin section of the Beijing-Harbin Expressway.

[0029] In the description of this invention, terms such as "upper," "lower," "left," "right," "inner," and "outer" that indicate orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and do not indicate or imply that the device referred to must have a specific orientation.

[0030] Figure 1 The image shows the right half of the bridge abutment after the reconstruction and expansion. Figure 1 The center line on the upper side is the road center line. Figure 1 and Figure 2 The right end is box girder 10. Figure 2 The left end of the middle box girder 10 is supported on the right-angled support platform 201 at the upper right of the cap girder 20. The back wall 202 and the corbel 203 extend vertically upward from the left side of the right-angled support platform 201. The right end of the support plate 30 is supported on the upper right side of the corbel 203. The lower end of the cap girder 20 is supported on the pier body 40.

[0031] This embodiment includes the following steps:

[0032] 1) Fabricate a supporting steel plate 1. One side of the supporting steel plate 1 is vertical, and the other side is inclined. The inclined side matches the shape of the left side of the cap beam 20 and the side of the back wall 202 and corbel 203 extending vertically upward from the left side of the cap beam 20. The maximum gap between the supporting steel plate 1 and the back wall side is no more than 5mm. If the maximum gap is greater than 5mm, rubber strips 2 are inserted to seal it. The thickness of the supporting steel plate is 10-12mm, the height H2 of the supporting steel plate is the distance from the top surface of the corbel to the bottom surface of the cap beam, and the bottom width B = 1.5-2m.

[0033] 2) After the reconstruction and expansion of half of the bridge abutment is completed but before backfilling with sand in layers, drill holes 5-10cm from the edge of the back wall end face, and insert plain round steel bars 2 at intervals of h = 50-80cm. Then, place the inclined side of the supporting steel plate 1 against the side of the cap beam 20, back wall 202, and corbel 203 facing the support plate 30, i.e., the abutment back side, and behind the four plain round steel bars 2. Weld the inclined side of the supporting steel plate 1 to the plain round steel bars 2 to fix it, thus fixing the supporting steel plate 1 to the abutment back side. The top of the supporting steel plate 1 is located under the slab 30, which effectively prevents backfill sand from flowing out from the bottom. The diameter of the plain round steel bars 2 is 8mm. ～ 10mm, implantation depth H2 = 810 ～ 820mm, exposed length H3=95 ～ 105mm.

[0034] 3) Fill the backfill sand on the side of the abutment in layers and compact it. Manually clean up the debris near the abutment of the central divider to prevent construction machinery from damaging the supporting steel plate 1. Stack medium and coarse sand on top of the support plate 30 to press down on the supporting steel plate 1 and prevent its bottom from deforming.

[0035] 4) At the junction of the slab 30 and the central divider, in the loose backfill sand area and partially voided areas under the slab 30, and on one longitudinal side of the slab 30, drill a row of grouting holes 3 at even intervals. The spacing between the grouting holes is 1.9–2.1 m. Figure 3 As shown, the angle between the drilling axis of grouting hole 3 and the vertical line, i.e., the drilling angle α, is 15°. ～ 45°, with a drilling depth of 1 / 2 the height of the back wall.

[0036] Grouting pipe 31 is made of solid-walled PVC pipe. A 15-20mm grout outlet hole 311 is pre-reserved at a distance of H1 = 400-600mm from the top of grouting pipe 31. Grouting pipe 31 is then pressed into the grout outlet hole 311. Before grouting, debris inside the grout outlet hole 311 is removed. The outer diameter of the grouting pipe is Φ40mm, the wall thickness is 5mm, and the top of the grouting pipe 31 extends 45-55mm above the original ground level.

[0037] 5) Since half of the bridge abutment is already open to traffic, its sides are exposed. To prevent the loss of grouting pressure, cement mortar is used to completely seal the sides to prevent cement grout leakage. After the cement grout used to seal the sides has completely hardened, the cement grout prepared by a forced mixer is injected into each grouting pipe 31 one by one using a hydraulic press or grouting machine. Grouting is stopped when the cement grout overflows from the sealed side or the grouting pipe is full and can no longer be injected. The opening of the grouting pipe 31 is then sealed with a rubber plug to prevent grout leakage, and then grouting is carried out on the next grouting pipe 31. This process is repeated until each grouting pipe 31 is grouted. After the cement grout in the grouting pipe 31 has completely hardened, the grouting pipe 31 is cut flat so that the top surface of the grouting pipe 31 and the hardened cement column inside it is level with the ground, thus completing the backfill sand anti-collapse treatment of the half of the bridge abutment. The pump pressure of the hydraulic press or grouting machine is 0.2-0.5 MPa, and the flow rate is 20-50 L / min.

[0038] 6) After the reconstruction and expansion of half of the bridge abutment is completed, repeat steps 1) to 5) to complete the backfilling of the abutment backfill with sand to prevent collapse of the other half of the bridge abutment.

[0039] In addition to the above embodiments, the present invention may have other implementation methods. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A method for preventing collapse of bridge abutments by backfilling sand behind them during reconstruction and expansion, characterized in that: Includes the following steps: 1) Process and manufacture a support steel plate, wherein one side of the support steel plate is vertical and the other side is inclined, and the inclined side matches the shape of the side of the cap beam and the back wall and the side of the corbel that extend vertically upward from one side of the cap beam. 2) After the reconstruction and expansion of half of the bridge abutment is completed but before backfilling with sand in layers, drill holes at intervals of 50-80cm between the upper and lower sides of the back wall edge and insert plain round steel bars. Then, the inclined side of the supporting steel plate is placed against the cap beam, back wall and corbel on the side facing the support plate, i.e., the back side of the abutment, and is located behind several plain round steel bars. Weld the inclined side of the supporting steel plate to the plain round steel bars to fix the supporting steel plate, so that the supporting steel plate is fixed on the back side of the abutment and the top of the supporting steel plate is located under the approach plate. 3) Fill the backfill sand on the side of the abutment in layers and compact it. Manually clean up the debris near the abutment of the central divider to prevent construction machinery from damaging the supporting steel plate. Stack coarse sand on top of the support plate to press down on the supporting steel plate and prevent its bottom from deforming. 4) At the junction of the slab and the central divider, in the loose sand area under the slab, in the voids and uncompacted areas, and on one longitudinal side of the slab, drill a row of multiple grouting holes at even intervals; use solid-walled PVC pipes for grouting, and reserve 15-20mm grout outlet holes at a distance of H1 = 400-600mm from the top of the grouting pipe. Remove debris from the grouting holes before grouting; then press the grouting pipes into the grouting holes respectively. 5) Since half of the bridge abutment has been opened to traffic, its side is exposed. In order to prevent the grouting pressure from dissipating, cement mortar is used to completely seal the side to prevent cement grout from leaking out. 6) After the side sealing cement grout has completely hardened, the cement grout prepared by the forced mixer is injected into each grouting pipe one by one through a hydraulic press or grouting machine; when the cement grout overflows from the side sealing or the grouting pipe is full and can no longer be injected, stop grouting, seal the grouting pipe opening with a rubber plug to prevent grout leakage, and then proceed to the next grouting pipe; repeat this process to complete the grouting of each grouting pipe one by one; after the cement grout in the grouting pipe has completely hardened, cut the grouting pipe flat so that the top surface of the grouting pipe and the hardened cement column inside is level with the ground, thus completing the backfill sand anti-collapse treatment of half of the bridge abutment; 7) After the reconstruction and expansion of half of the bridge abutment is completed, repeat steps 1) to 6) to complete the backfilling of the abutment backfill sand to prevent collapse of the other half of the bridge abutment.

2. The method for preventing collapse of bridge abutments by backfilling sand as described in claim 1, characterized in that: In step 2), the maximum gap between the supporting steel plate and the back of the platform shall not exceed 5mm. If the maximum gap exceeds 5mm, a rubber strip shall be inserted to seal it. The thickness of the supporting steel plate is 10-12mm, the height H1 of the supporting steel plate is the distance from the top surface of the corbel to the bottom surface of the cap beam, and the bottom width B is 1.5-2m.

3. The method for preventing collapse of bridge abutments by backfilling sand as described in claim 1, characterized in that: In step 2), the diameter of the plain round steel bar is 8 mm. ～ 10mm, implantation depth H2 = 810 ～ 820mm, exposed length H3=95 ～ 105mm.

4. The method for preventing collapse of bridge abutments by backfilling sand as described in claim 1, characterized in that: In step 4), the spacing between multiple grouting holes in a row is 1.9–2.1 m, and the drilling angle α between the drilling axis and the vertical is 15°. ～ 45°, with a drilling depth of 1 / 2 the height of the back wall.

5. The method for preventing collapse of bridge abutments by backfilling sand as described in claim 1, characterized in that: The outer diameter of the grouting pipe in step 4) is φ40mm and the wall thickness is 5mm; the top of the grouting pipe is 45-55mm above the original ground surface.

6. The method for preventing collapse of bridge abutments by backfilling sand as described in claim 1, characterized in that: In step 6), the pump pressure of the hydraulic press or grouting machine is 0.2-0.5 MPa, and the flow rate is 20-50 L / min.

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