CN104594331A - Method for reinforcing road high-stacked culvert foundation - Google Patents

Abstract

The invention discloses a method for reinforcing a road high-stacked culvert foundation. The method comprises the following steps: (1) excavating refilling grooves through an excavator along a direction parallel to the axial direction of a culvert; (2) refilling broken stones into the refilling grooves, and grouting cement paste into broken stone gaps, wherein the grouted cement paste and the broken stones are constructed into a reinforcing area for carrying upper load together with foundation soil; (3) checking the reinforcing effect by adopting a static load test after 6-9 days of the completion of grouting, and performing upper structure construction and roadbed filling after the design requirement is met by the carrying force. According to the method, the grooves are excavated with the excavator along the axial direction of the culvert, the reinforcing area is constructed by refilling the broken stones and grouting the cement paste, and the reinforcing area and foundation soil on both sides carry upper load together, thereby forming a novel bilaterally-reinforced composite foundation. The rigidity of the foundation is adjusted by adjusting the depths of the formed grooves and the distances among the formed grooves. Compared with the prior art, the method for reinforcing the road high-stacked culvert foundation is low in cost, is easy to operate, is wide in adaptability, and is easy for ensuring the quality.

Description

A method for foundation reinforcement of high-fill culverts in highways

technical field

The invention relates to the technical field of building construction, in particular to a foundation reinforcement method for high-fill culverts in highways.

Background technique

High fill culverts on highways usually have a height of more than 10 m, and some even exceed 50 m. Due to the large filling load, the foundation of the culvert bears a large vertical load, and there are problems such as stress concentration and excessive deformation of the foundation of the culvert, which may easily cause diseases such as uneven settlement and excessive settlement of the culvert. These diseases can cause cracking, leakage or water accumulation in culverts, or cause damage to culvert structures, or even collapse, seriously affecting the normal use of culverts and roads.

At present, the foundation reinforcement measures for high-fill culverts in highways are mainly based on the replacement of cushions. The replacement cushion method is to excavate the weak soil layer within a certain range under the foundation when the bearing layer under the foundation of the building (structure) is relatively weak and cannot meet the requirements of the superstructure load on the foundation, and then backfill it with a lower strength. A method of compacting large sand, gravel or lime soil, etc., as the bearing layer of the foundation. Although the cushion replacement method can improve the bearing capacity of the foundation and reduce the compression of the foundation to a certain extent, it still has the following shortcomings: (1) The treatment depth of the cushion replacement method generally does not exceed 3m , It is not suitable for the treatment of deep and weak foundations; (2) It is not easy to ensure the compaction of sand and gravel fillers by replacing the cushion method; (3) The construction period of large-area replacement of sand and gravel fillers is long, the cost is high, and the damage to the environment is great.

Contents of the invention

The object of the present invention is to propose a low-cost, high-reliability, easy-to-adjust control, wide adaptability, and good technical and economical highway high-fill culvert foundation reinforcement method in order to avoid the above-mentioned deficiencies in the prior art.

The invention discloses a method for reinforcing the foundation of a high-fill culvert for highways, which is suitable for the reinforcement of the foundation of a high-fill culvert with insufficient bearing capacity, and comprises the following steps:

⑴Excavate the backfill groove along the direction parallel to the axis of the culvert through the excavator;

(2) Backfill gravel into the backfill groove, and pour cement slurry into the gaps of the gravel. The grouting and gravel together constitute a reinforcement area, which together with the foundation soil is used to bear the upper load;

⑶ 6-9 days after the pouring is completed, use the static load test to check the reinforcement effect, and after the bearing capacity meets the design requirements, carry out the superstructure construction and embankment filling.

The excavation width of the backfill groove is equal to the width of the grab bucket of the excavator.

The excavation depth of the backfill groove is determined through a load test according to the requirements of the bearing capacity of the foundation.

The distance between the backfill grooves is calculated and determined according to the method of calculating the area replacement rate in the composite foundation theory.

The diameter of the crushed stone is 20-50mm, and the mud content is less than 10%.

The cement slurry is plain cement slurry, and the water-cement ratio is 0.4-0.45.

The beneficial effects of the present invention are: the present invention adopts the excavator to excavate the groove along the axis of the culvert, and backfills gravel and pours cement slurry to form a reinforcement area, and the reinforcement area and the foundation soil on both sides bear the upper load jointly, forming a new type of two-way Enhanced composite foundation. By adjusting the groove depth and groove spacing to adjust the foundation stiffness, compared with the existing similar technology, it is a low-cost, easy-to-operate, wide-applicability, and quality-guaranteed foundation reinforcement method for high fill culverts.

Description of drawings

Fig. 1 is the schematic diagram of the culvert structure after adopting the method of the present invention.

Marks in the figure: 1-culvert, 2-foundation, 3-backfill tank, 4-gravel, 5-cement slurry, 6-reinforcement area.

Detailed ways

The foundation reinforcement method for high-fill culverts in highways of the present invention is suitable for the foundation reinforcement of high-fill culverts 1 when the bearing capacity is insufficient. The method first excavates the backfill groove 3 on the foundation 2 along the axis of the culvert by an excavator. In step 3, backfill gravel 4 and pour cement slurry 5 to form reinforcement area 6, so that foundation soil 2 and reinforcement area 6 together form a new type of composite foundation to achieve the purpose of strengthening the weak foundation. Adjusting the foundation stiffness by adjusting the depth of grooves and the distance between grooves is a low-cost, high-reliability, easy-to-adjust control, wide adaptability, and good technical and economical foundation reinforcement method.

Specifically include the following steps:

A: According to the requirements of the bearing capacity of the high-fill culvert foundation, the depth and spacing of the required excavation and backfilling grooves are preliminarily determined according to the method of calculating the area replacement rate in the composite foundation theory, and the modulus of the grouting reinforcement area in the backfilling grooves is determined through laboratory tests.

B: In the foundation, according to the excavation depth and spacing determined in the previous step, use the excavator to excavate the backfill groove along the axis of the culvert, and the width of the backfill groove is equal to that of the excavator grab.

C: Backfill the gravel filler in the backfill tank, pour cement slurry and stir at the same time, so that the gravel can be uniformly coagulated to form a reinforcement area. Seven days after the construction is completed, the static load test is used to check the reinforcement effect and verify whether the bearing capacity of the foundation meets the requirements.

Wooden invention is described in further detail below in conjunction with specific embodiment:

Example 1

The foundation of a high-fill culvert on a highway in a mountainous area is: 0-0.8m is miscellaneous fill, 0.8-3.4m is silty clay: yellowish brown; 3.4-5.8m is clay, yellow, brown-gray, plastic to hard plastic. The bearing capacity of the foundation at 3.6m below the ground is 240kPa in field tests, and the design value of the foundation bearing capacity of the high fill culvert is 320kPa, which cannot meet the design requirements.

The design excavation depth of the backfill tank is 4.0m, the area replacement rate is 40%, the particle size of the mixed gravel is 3-5cm, and the water-cement ratio of the cement slurry is 0.42.

During construction, a hydraulic crawler backhoe excavator is used to form grooves on the foundation, and the depth of the grooves is about 3.5m. After the grooves are completed, the bottom is cleaned manually. Ordinary Portland cement No. 325 is used to configure the cement slurry. The water-cement ratio of the cement slurry is 0.42. The cement slurry is poured into the gap between the crushed stones to form a reinforcement area. After the grouting is completed 7 days, the on-site static load test is carried out to determine the bearing capacity achieved. force. After the bearing capacity meets the design requirements, the superstructure construction and embankment filling will be carried out.

Example 2

The foundation of a high-fill culvert on an expressway is: 0-3m silty clay: gray, brown-gray, strong viscosity; 3-7m clay, yellow, brown-gray, hard plastic.

The excavation depth of the backfill tank is designed to be 3.5m, the area replacement rate is 50%, the particle size of the mixed gravel is 4-5cm, and the water-cement ratio of the cement slurry is 0.42.

During construction, a hydraulic crawler-type backhoe excavator is used to form grooves on the foundation, and the depth of the grooves is about 3.5m. After the grooves are completed, the bottom is cleaned manually. Ordinary Portland cement No. 325 is used to configure the cement slurry. The water-cement ratio of the cement slurry is 0.42. The cement slurry is poured into the gaps between the crushed stones to form a reinforcement area. After the grouting is completed 7 days, the on-site static load test is carried out to confirm that the bearing capacity meets the design. Upon request, carry out superstructure construction and embankment filling.

The above-mentioned specific embodiment is only the preferred embodiment of the present invention, and is not used to limit the implementation of the present invention and the scope of claims. All equivalent changes and modifications made according to the content described in the patent protection scope of the present invention application shall be Included in the application scope of the present invention.

Claims (6)

1. A high filling culvert foundation reinforcement method for highway, is characterized in that comprising the following steps: ⑴Excavate the backfill groove along the direction parallel to the axis of the culvert through the excavator; (2) Backfill gravel into the backfill groove, and pour cement slurry into the gaps of the gravel. The grouting and gravel together constitute a reinforcement area, which together with the foundation soil is used to bear the upper load; ⑶ 6-9 days after the pouring is completed, use the static load test to check the reinforcement effect, and after the bearing capacity meets the design requirements, carry out the superstructure construction and embankment filling. 2. The method for strengthening the foundation of high-fill culverts in highways according to claim 1, wherein the excavation width of the backfill groove is equal to the width of the grab bucket of the excavator. 3. The method for strengthening the foundation of high fill culverts in highways according to claim 1, characterized in that: the excavation depth of the backfill trench is determined through a load test according to the requirements of the bearing capacity of the foundation. 4. The method for strengthening the foundation of high fill culverts in highways as claimed in claim 1, characterized in that: the distance between the backfill grooves is calculated and determined according to the method for calculating the area replacement rate in the composite foundation theory. 5. The method for strengthening the foundation of high-fill culverts in highways according to claim 1, wherein the crushed stones have a diameter of 20-50 mm and a mud content of less than 10%. 6. The method for strengthening the foundation of high-fill culverts in highways according to claim 1, wherein the cement slurry is plain cement slurry, and the water-cement ratio is 0.4-0.45.