CN111364306A

CN111364306A - Construction method for reducing settlement of high-fill subgrade after construction by using collapsible loess

Info

Publication number: CN111364306A
Application number: CN202010221038.7A
Authority: CN
Inventors: 贾国军; 吕雨; 张宁; 张彬
Original assignee: China MCC17 Group Co Ltd
Current assignee: China MCC17 Group Co Ltd
Priority date: 2020-03-26
Filing date: 2020-03-26
Publication date: 2020-07-03

Abstract

The invention discloses a construction method for reducing settlement of a high-fill subgrade of collapsible loess after construction, and relates to the technical field of subgrade construction. The construction method for reducing settlement of the collapsible loess high fill roadbed after construction comprises the following steps: and S1, reinforcing the first layer of rammed surface by using the dynamic compaction machine after the roadbed backfilling thickness reaches the effective reinforcing depth of the dynamic compaction machine, continuously backfilling earthwork after the reinforcing treatment is finished, and reinforcing the second layer of rammed surface by using the dynamic compaction machine when the backfilling thickness reaches the effective processing depth of the dynamic compaction machine again. This reduce collapsible loess high fill road bed construction method that subsides after-construction utilizes the dynamic compactor to tamp according to the ramming point of arranging and consolidates, treats that the second tamps all to accomplish the back and carries out the flattening to the second ramming point and roll, begins the backfill again after the construction, takes the dynamic compaction to reinforce backfill soil, and the effect is showing, can reduce to a great extent and subside after-construction with the high fill road bed of collapsible loess as filler.

Description

Construction method for reducing settlement of high-fill subgrade after construction by using collapsible loess

Technical Field

The invention relates to the technical field of roadbed construction, in particular to a construction method for reducing settlement of a collapsible loess high fill roadbed after construction.

Background

The collapsible loess refers to soil which undergoes significant additional deformation due to structural damage of soil after being soaked under the action of self-weight stress of an overlying soil layer or under the combined action of the self-weight stress and additional stress, and belongs to special soil. The soil is uniform, the structure is loose, and pores are developed. Generally, the strength is higher and the compressibility is lower when not wetted by water. When soaked by water under a certain pressure, the soil structure is quickly damaged, large additional subsidence is generated, and the strength is quickly reduced.

In the prior art, the method for controlling the water content is usually adopted for the collapsible loess high fill roadbed, so that the compaction effect is optimal. However, repeated tests prove that the influence of the backfill of the previous layer on the compaction degree of the backfill of the next layer in the rolling process is great in the soil backfilling process, so that the integral compaction effect of the filled soil body is poor, the construction quality of the roadbed is difficult to guarantee, the natural settling time after construction is long, the settling amount is large, and the road surface structure layer can be influenced seriously through the reflection action.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides a construction method for reducing settlement of a collapsible loess high fill roadbed after construction, and solves the problems that the overall compaction effect of the collapsible loess high fill roadbed is poor, the natural settlement time after construction is long, the settlement amount is large, and the construction quality is difficult to ensure in the prior art.

(II) technical scheme

In order to achieve the purpose, the invention is realized by the following technical scheme: a construction method for reducing settlement of a collapsible loess high fill roadbed after construction comprises the following steps:

s1, after the roadbed backfilling thickness reaches the effective reinforcing depth of the dynamic compaction machine, reinforcing the first layer of rammed surface by using the dynamic compaction machine, continuously backfilling earthwork after the reinforcing treatment is finished, when the backfilling thickness reaches the effective processing depth of the dynamic compaction machine again, reinforcing the second layer of rammed surface by using the dynamic compaction machine, and repeating the steps in the subsequent earthwork backfilling and tamping operation;

s2, arranging first-pass tamping points on the tamping surface of the first layer by dynamic compaction according to the arrangement intervals of the tamping points, and then tamping and reinforcing the arranged tamping points by using a dynamic compactor;

s3, after the first tamping is finished, leveling and rolling the tamping surface, arranging tamping points for the second time according to the tamping point arrangement intervals after rolling, then tamping and reinforcing the tamping points for the second time by using a dynamic compactor, leveling and rolling the tamping points for the second time after the second tamping is completely finished, and refilling after construction is finished.

Preferably, in step S1, the effective treatment depth of the dynamic compactor is determined by field test segment summary.

Preferably, in step S1, the dynamic compaction machine is a crawler-type dynamic compaction machine, the weight of the ram is 12 tons, the diameter of the ram is 2 meters, the drop distance is 10 meters, the effect reinforcement depth is 8 meters, and the effective reinforcement depth is 4 meters.

Preferably, in step S1, the dynamic compaction machine is used for tamping in two passes, the first pass is tamping with a distance of 3 meters between points, the quincunx arrangement is adopted, the tamping frequency is 6 times per point, and the second pass is tamping with full tamping, so as to ensure no dead angle in tamping.

Preferably, after the full-section first-time dynamic compaction is completed, a grader is used for completely removing the impact soil with the thickness of about 15cm on the surface of the roadbed, a vibratory roller is used for rolling after the leveling, and the second-time compaction is performed after the compaction degree meets the requirement.

(III) advantageous effects

The invention provides a construction method for reducing settlement of a high-fill subgrade of collapsible loess after construction. The method has the following beneficial effects: according to the construction method for reducing the post-construction settlement of the high fill roadbed by using the collapsible loess, the traditional construction process is improved, the crawler-type dynamic compaction machine is adopted for power consolidation, the engineering property of the collapsible loess is changed, gaps of soil bodies are compacted, the compressibility of the fill soil bodies is greatly reduced, the settlement amount during construction can reach 80% -90% of the designed load settlement amount, compared with natural settlement, the post-construction settlement amount of the high fill roadbed is greatly reduced, the overall stability of the newly built roadbed is ensured, the engineering quality is improved, and the phenomenon that the whole settlement caused by the post-construction settlement of the high fill roadbed by taking the collapsible loess as the filler effectively prevents the pavement cracking phenomenon; the construction process is simple, the operation is simple and convenient, the construction management and the quality control are relatively easy, the work efficiency is high, the construction speed is high, the construction period is shortened, and the construction cost is saved.

Drawings

FIG. 1 is a schematic view of the subgrade filling of the present invention;

FIG. 2 is a construction ramming point layout of the present invention;

FIG. 3 is a working principle diagram of the dynamic compactor of the invention.

In the figure: 1. strongly tamping the first layer of tamping surface; 2. strongly tamping the second layer of tamping surface; 3. the dynamic compactor effectively reinforces the depth; 4. arranging intervals of tamping points; 5. tamping points for the first time; 6. tamping points for the second time; 7. a dynamic compaction machine; 8. The drop distance of a rammer; 9. the reinforcing depth is influenced by the dynamic compactor.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-3, the present invention provides a technical solution: a construction method for reducing settlement of a collapsible loess high fill roadbed after construction comprises the following steps:

s1, after the roadbed backfilling thickness reaches the effective reinforcing depth 3 of the dynamic compactor, reinforcing the first layer of ramming surface 1 by using the dynamic compactor 7, and continuously backfilling earthwork after the reinforcing treatment is finished, when the backfilling thickness reaches the effective processing depth 3 of the dynamic compactor again, reinforcing the second layer of ramming surface 2 by using the dynamic compactor 7, and repeating the steps of the subsequent earthwork backfilling and ramming operation, wherein the effective processing depth 3 of the dynamic compactor is determined by field through test section summary, the dynamic compactor 7 is a crawler-type dynamic compactor, the weight of a rammer is 12 tons, the diameter of the rammer is 2 meters, the drop distance is 10 meters, the influence reinforcing depth 9 is 8 meters, the effective reinforcing depth 3 is 4 meters, the dynamic compactor 7 is compacted twice, the first-time ramming point interval is 3 meters, quincunx arrangement is adopted, the ramming times of each point are 6 times, and the second-time ramming is full compaction, so that no dead angle exists in the ramming process is ensured;

s2, arranging first-pass tamping points 5 on the first-layer tamping surface 1 by dynamic compaction according to the tamping point arrangement interval 4, and then tamping and reinforcing the arranged tamping points by using a dynamic compactor 7;

s3, after the first-time tamping of the tamping points 5 is completed, leveling and rolling are carried out on a tamping surface, after the rolling is completed, the second-time tamping points 6 are arranged according to the tamping point arrangement intervals 4, then the dynamic compactor 7 is used for tamping and reinforcing according to the arranged tamping points, after the second-time tamping is completely completed, the second-time tamping points 6 are leveled and rolled, and after the construction is completed, backfilling is started again, wherein after the first-time dynamic compaction of the full section is completed, the grader is used for shoveling 15 cm-thick impact virtual soil on the surface of the roadbed, after the leveling, the vibratory roller is used for rolling, and after the compaction degree meets the requirement, the second-time tamping work is carried out.

In conclusion, the construction method for reducing the post-construction settlement of the high filling subgrade of the collapsible loess has the advantages that the construction method improves the traditional construction process, adopts the crawler-type dynamic compactor to carry out dynamic consolidation, changes the engineering property of the collapsible loess, compacts soil gaps, greatly reduces the compressibility of the filling soil, and greatly reduces the settlement amount during construction to 80-90% of the designed load settlement amount, compared with natural settlement, greatly reduces the post-construction settlement amount of the high filling subgrade, ensures the overall stability of the newly-built subgrade, improves the engineering quality, and effectively prevents the pavement cracking phenomenon caused by the overall settlement caused by the post-construction settlement of the high filling subgrade taking the collapsible loess as the filler; the construction process is simple, the operation is simple and convenient, the construction management and the quality control are relatively easy, the work efficiency is high, the construction speed is high, the construction period is shortened, and the construction cost is saved.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The utility model provides a construction method that subsides after reducing collapsible loess high fill road bed construction which characterized in that: the method comprises the following steps:

s1, after the roadbed backfill thickness reaches the effective reinforcement depth (3) of the dynamic compaction machine, reinforcing the first layer of ramming surface (1) by using the dynamic compaction machine (7), continuously backfilling earthwork after the reinforcing treatment is finished, when the backfill thickness reaches the effective treatment depth (3) of the dynamic compaction machine again, reinforcing the second layer of ramming surface (2) by using the dynamic compaction machine (7), and repeating the steps in the subsequent earthwork backfill tamping operation;

s2, arranging first-time tamping points (5) on the first-layer tamping surface (1) through dynamic compaction according to the tamping point arrangement distance (4), and then tamping and reinforcing the arranged tamping points through a dynamic compactor (7);

s3, after the tamping of the tamping points (5) for the first time is finished, leveling and rolling are carried out on the tamping surface, after the rolling is finished, the tamping points (6) for the second time are arranged according to the tamping point arrangement intervals (4), then the dynamic compactor (7) is utilized to tamp and reinforce the tamping points arranged according to the tamping points, after the tamping for the second time is completely finished, the tamping points (6) for the second time are leveled and rolled, and the backfilling is restarted after the construction is finished.

2. The construction method for reducing settlement of the collapsible loess high fill roadbed as claimed in claim 1, wherein: in step S1, the effective treatment depth (3) of the dynamic compactor is determined from the field by test segment summary.

3. The construction method for reducing settlement of the collapsible loess high fill roadbed as claimed in claim 1, wherein: in step S1, the dynamic compactor (7) is a crawler-type dynamic compactor, the weight of the ram is 12 tons, the diameter of the ram is 2 meters, the drop distance (8) is 10 meters, the effective reinforcement depth (9) is 8 meters, and the effective reinforcement depth (3) is 4 meters.

4. The construction method for reducing settlement of the collapsible loess high fill roadbed as claimed in claim 1, wherein: in step S1, the dynamic compactor (7) is tamped twice, the distance between points is 3 meters in the first tamping, the quincunx arrangement is adopted, the tamping times are 6 times per point, and full tamping is adopted in the second tamping, so that no dead angle is ensured in tamping.

5. The construction method for reducing settlement of the collapsible loess high fill roadbed as claimed in claim 1, wherein: and after the full-section first-time dynamic compaction is finished, using a grader to completely remove the 15 cm-thick impact soil on the surface of the roadbed, rolling by using a vibratory roller after the leveling, and performing second-time compaction after the compaction degree meets the requirement.