Construction method for controlling differential settlement at excavation and filling junction of yard road foundation

Abstract

The invention relates to the technical field of engineering construction, and discloses a construction method for controlling differential settlement at the excavation and filling junction of a field road foundation, which comprises the following steps: treatment of an excavation area: firstly, comprehensively removing non-engineering soil in an engineering range, such as turf, tree roots and the like; a mechanical operation mode (such as a bulldozer, a loader, a hydraulic backhoe and the like) is adopted for efficient excavation; the backfill area is thoroughly cleaned before backfill, impurities which are not beneficial to soil compaction are removed, and impact rolling experimental construction is carried out. According to the construction method for controlling differential settlement at the excavation and filling junction of the runway foundation, through the unique construction method, the defects of a traditional method are overcome, the bearing capacity of foundation soil can be effectively improved, the stability and safety of an airport runway in the construction process and the landing and taking-off processes of an airplane are guaranteed, and the construction period is shortened. And on the premise that foundation deformation can be effectively reduced, the foundation settlement construction problem is effectively solved, and the engineering quality after construction is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of engineering construction, and in particular to a construction method for controlling differential settlement at the junction of excavation and filling of a field road foundation. Background Art

[0002] With the development of social economy, airports, as important infrastructure, have become increasingly necessary in cities. In recent years, a large number of new general airports have been built. However, due to the large area of ​​airports and high requirements for the surrounding environment, there are few sites suitable for direct airport construction. Some airports can only be located in areas with poor geological conditions such as mountainous areas and river beaches. Therefore, it is necessary to carry out foundation treatment on the site to ensure the quality and stability of the project construction.

[0003] The soil conditions during foundation construction vary greatly, resulting in large differences in settlement at the junction of cut and fill. The junction of cut and fill is a sensitive area for settlement differences, and measures to control differential settlement need to be taken. Traditional construction methods cannot avoid settlement.

[0004] In order to solve the above problems, the present invention provides a construction method for controlling differential settlement at the junction of excavation and filling of field foundation, which can significantly improve the shear strength and bearing capacity of the foundation, avoid uneven settlement, and ensure the quality of the project after construction. Summary of the invention

[0005] The purpose of the present invention is to provide a construction method for controlling differential settlement at the junction of excavation and filling of a field road foundation, which can significantly improve the shear strength and bearing capacity of the foundation soil, avoid uneven settlement, and ensure the quality of the project after construction.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a construction method for controlling differential settlement at the junction of excavation and filling of a field road foundation, comprising the following steps:

[0007] Treatment of excavation area: First, completely remove non-engineering soil within the scope of the project, such as grass, tree roots, etc., and use mechanized operation methods (such as bulldozers, loaders, hydraulic backhoes, etc.) for efficient excavation;

[0008] Treatment of backfill area: Before backfilling, the backfill area should be thoroughly cleaned to remove impurities that are not conducive to soil compaction, and impact rolling test construction should be carried out;

[0009] Dynamic tamping reinforcement treatment: After backfilling to the designed elevation, reserve the construction height of the geogrid, and then carry out dynamic tamping reinforcement;

[0010] Over-excavation replacement cushion layer setting: After the earth and stone on the overlap surface are backfilled to the designed elevation, an over-excavation replacement cushion layer is set on the excavation side, with a total thickness of 1.5 meters, containing two layers of bidirectional geogrids, located at 0.5 meters and 1.0 meters respectively, and the grid backfill section is 1.0 meters; the strong tamping reinforcement on the fill side must be carried out before laying the geogrid;

[0011] Engineering testing: The sand filling method is used to allow sand with uniform particles (or a single particle size) to fall freely from a certain height into a cylinder or hole of a specified volume. The volume of the test hole is measured based on the principle of constant unit mass, thereby inferring the density of the soil or pavement material.

[0012] Preferably, in the excavation area processing step, during the excavation process, if the original terrain surface inclination is consistent with the slope direction and the slope is steeper than 1:5, it is necessary to excavate into steps, and the step height is controlled according to the specifications.

[0013] This method first removes the grass, tree roots, plant soil, local soft soil, artificial fill and domestic garbage within the project scope and transports them to the designated location; then, bulldozers, large loaders, hydraulic backhoes and electric shovels are used to excavate the earth, and dump trucks are used to transport the abandoned soil to the designated waste dump. When the surface inclination of the original terrain is consistent with the slope direction and the slope is steeper than 1:5, a step excavation method is used to ensure the stability of the slope and reduce the amount of excavation.

[0014] Preferably, in the filling area treatment step, before backfilling, the cultivated soil, silt, humus, loose soil, loose soil, pumice and foreign soil in the backfill area are thoroughly removed, and an impact rolling test construction is carried out to determine the layered paving thickness, the number of rolling times and the appropriate moisture content range to ensure the compaction effect.

[0015] Preferably, in the strong tamping reinforcement treatment step, the treatment depth is not less than 5 meters, and a combination of two 2000 KN.m spot tamping and one 1000 KN.m full tamping is adopted, and the cushion layer thickness is at least 1.0 meter.

[0016] After backfilling to the designed elevation, the foundation is reinforced by the strong tamping method. The treatment depth is required to be no less than 5m. Two times of 2000KN.m spot tamping + one time of 1000KN.m full tamping are used. The thickness of the cushion layer is temporarily set at 1.0m. By precisely controlling the tamping energy and the number of tamping times, it is ensured that the foundation reaches the design bearing capacity. At the same time, the construction height of the geogrid is reserved to facilitate the subsequent reinforcement treatment.

[0017] Preferably, in the step of setting up the over-excavation and replacement cushion layer, the over-excavation and replacement cushion layer uses crushed stone soil filler that meets the relevant technical requirements of earthwork engineering, requiring the maximum particle size of the crushed stone soil not exceeding 10 cm, good gradation, and a solid volume ratio of not less than 83%.

[0018] An over-excavation and replacement cushion layer is set at the junction of excavation and filling, and high-quality crushed stone and soil filling material is used to improve the overall stability and bearing capacity of the foundation. The total thickness of the cushion layer is 1.5 meters, and it contains two layers of bidirectional geogrids, which are located at 0.5 meters and 1.0 meters respectively. The grid inverted section is 1.0 meter. The tensile strength and deformation resistance of the foundation are further enhanced through the reinforcement effect of the grid. The over-excavation and replacement cushion layer uses crushed stone and soil filling material that meets the relevant technical requirements of earthwork engineering. The maximum particle size of the crushed stone and soil is required to be no more than 10 cm, the grading is good, and the solid volume ratio is not less than 83%.

[0019] Preferably, in the engineering inspection step, the volume of the test hole is indirectly calculated by measuring a certain mass of sand freely falling from a fixed height into a container of known volume (such as a test hole), and then the volume is used to represent the volume of the excavated soil or pavement material. Then, by comparing this volume with the mass of the volume of material, the density of the soil or pavement material can be calculated.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0021] First, the present invention solves the shortcomings of traditional methods through a unique construction method, can effectively improve the bearing capacity of the foundation soil, and ensure the stability and safety of the airport runway during the construction process and during the landing and take-off of the aircraft. It can also effectively solve the construction problem of foundation settlement while ensuring the effective reduction of foundation deformation, and ensure the quality of the project after construction.

[0022] Second, the present invention adopts the sand filling method to indirectly calculate the volume of the test hole by measuring a certain mass of sand freely falling from a fixed height into a container of known volume (such as a test hole). The volume is then used to represent the volume of the excavated soil or pavement material. Then, by comparing this volume with the mass of the volume of material, the density of the soil or pavement material can be calculated. The invention has the advantages of simple operation and reliable measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the construction process structure of the present invention;

[0024] Figure 2 This is a schematic diagram of the structure of the excavation area processing flow of the present invention;

[0025] Figure 3 This is a schematic diagram of the structure of the filling area treatment process of the present invention;

[0026] Figure 4 This is a structural schematic diagram of the dynamic tamping reinforcement process of the present invention;

[0027] Figure 5 This is a schematic diagram of the structure of the process of setting up the over-excavation and replacement of the cushion layer of the present invention;

[0028] Figure 6 It is a schematic diagram of the structure of the engineering detection process of the present invention;

[0029] Figure 7 This is a schematic diagram of the large-scale structure of the excavation-filling interface treatment of the present invention;

[0030] Figure 8 It is a schematic diagram of the arrangement structure of the strong compaction points of the present invention. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] See also Figure 1-8 A construction method for controlling differential settlement at the junction of excavation and filling of a field road foundation comprises the following steps:

[0033] 1. Treatment of excavation area: First, completely remove non-engineering soil within the scope of the project, such as grass, tree roots, etc., and use mechanized operation methods (such as bulldozers, loaders, hydraulic backhoes, etc.) for efficient excavation;

[0034] This method first removes the grass, tree roots, plant soil, local soft soil, artificial fill and domestic garbage within the project scope and transports them to the designated location; then, bulldozers, large loaders, hydraulic backhoes and electric shovels are used to excavate the earth, and dump trucks are used to transport the abandoned soil to the designated waste dump. When the surface inclination of the original terrain is consistent with the slope direction and the slope is steeper than 1:5, a step excavation method is used to ensure the stability of the slope and reduce the amount of excavation.

[0035] 2. Treatment of backfill area: Before backfilling, the backfill area should be thoroughly cleaned to remove impurities that are not conducive to soil compaction, and impact rolling test construction should be carried out;

[0036] Before backfilling, thoroughly remove cultivated soil, silt, humus, loose soil, loose soil, pumice and impurity soil in the backfill area, and carry out impact rolling test construction. According to the selected compaction method, compaction machinery type, compaction function and compaction degree requirements, carry out on-site impact rolling test construction. Through on-site impact rolling test, determine the layered paving thickness, number of rolling times and appropriate control range of moisture content.

[0037] 3. Dynamic tamping reinforcement treatment: After backfilling to the designed elevation, reserve the construction height of the geogrid, and then carry out dynamic tamping reinforcement;

[0038] After backfilling to the design elevation, the foundation is reinforced by strong tamping method. The treatment depth is required to be no less than 5m. Two times of 2000KN.m spot tamping and one time of 1000KN.m full tamping are used. The cushion thickness is tentatively set at 1.0m. By accurately controlling the tamping energy and the number of tamping times, it is ensured that the foundation reaches the design bearing capacity. At the same time, the construction height of the geogrid is reserved to facilitate the subsequent reinforcement treatment.

[0039] The procedure for the strong compaction construction is as follows: clean and level the site, lay a gravel cushion layer → mark the first tamping point position and measure the site elevation → put the crane in place and aim the tamping hammer at the service point → measure the elevation of the hammer top before tamping → lift the tamping hammer to a predetermined height, unhook it and let it fall freely to measure the elevation of the hammer top → run back and forth, complete the tamping of one tamping point according to the specified number of tamping times and control standards → repeat the above steps to complete the first tamping of all tamping points → fill the tamping pit with a bulldozer and measure the site elevation → after the specified interval, complete all tamping times according to the above procedure → compact the loose soil on the surface of the site with low-energy full tamping, and measure the site elevation after tamping.

[0040] 4. Setting of over-excavation replacement cushion layer: After the earth and stone of the overlap surface are backfilled to the designed elevation, an over-excavation replacement cushion layer is set on the excavation side, with a total thickness of 1.5 meters, containing two layers of bidirectional geogrids, located at 0.5 meters and 1.0 meters respectively, and the grid reverse section is 1.0 meters; the strong tamping reinforcement on the fill side must be carried out before laying the geogrid;

[0041] An over-cut and replacement cushion layer is set at the junction of cut and fill, using high-quality crushed stone soil filler to improve the overall stability and bearing capacity of the foundation. The total thickness of the cushion layer is 1.5 meters, containing two layers of bidirectional geogrids, located at 0.5 meters and 1.0 meters respectively, and the grid reverse section is 1.0 meters. Through the reinforcement effect of the grid, the tensile strength and deformation resistance of the foundation are further enhanced;

[0042] The over-excavation replacement cushion layer shall be made of crushed stone soil filler that meets the relevant technical requirements of earthwork engineering, requiring the maximum particle size of the crushed stone soil to be no more than 10cm, with good gradation and a solid volume ratio of no less than 83%;

[0043] The specific parameters of the bidirectional geogrid are detailed in the technical parameter table

[0044]

[0045] 5. Engineering testing: Using the sand filling method, sand with uniform particles (or single particle size) is freely dropped from a certain height into a cylinder or hole of a specified volume. The volume of the test hole is measured based on the principle of constant unit mass, thereby calculating the density of the soil or road surface material;

[0046] The sand filling method indirectly calculates the volume of the test hole by measuring a certain mass of sand falling freely from a fixed height into a container of known volume (such as a test hole), and then uses this volume to represent the volume of the excavated soil or pavement material. Then, by comparing this volume with the mass of the volume of material, the density of the soil or pavement material can be calculated.

[0047] The general steps of sand filling method detection are:

[0048] Preparation stage: Select appropriate sand, which should be clean and of uniform particle size (usually single particle size or sand that meets certain particle size distribution requirements) to ensure the stability and accuracy of its unit mass (or "sand filling density"). At the same time, prepare standard sand measuring cylinders, test hole excavation tools, weighing equipment, etc.

[0049] Calibration of sand: Before the formal test, the sand needs to be calibrated, that is, the mass of sand per unit volume (sand filling density) is measured. This is usually done by filling the sand into a container of known volume multiple times and measuring the mass of the filled sand to obtain the average value.

[0050] Test hole excavation: dig a test hole in the soil or pavement material to be tested according to the specified size and depth. The size and depth of the test hole must be determined according to the test standards and material properties;

[0051] Sand filling operation: Pour the calibrated sand into the test hole from a certain height until the sand surface is flush with the edge of the test hole. During the sand filling process, the sand should be prevented from being disturbed by external factors (such as wind, vibration, etc.);

[0052] Quality measurement: After the sand filling is completed, the quality of the sand in the test hole should be measured and recorded immediately. This step should be completed in the shortest possible time to avoid changes in the sand quality due to environmental factors (such as humidity changes);

[0053] Density calculation: Based on the mass of sand in the test hole and the density of the filled sand, the volume of the test hole can be calculated. Combined with the mass of the excavated material, the density of the soil or pavement material can be calculated.

[0054] The sand filling method has the advantages of simple operation and reliable measurement results. It is an effective method to determine the density of soil or pavement materials.

[0055] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit thereof, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A construction method for controlling differential settlement at the junction of excavation and filling of a field road foundation, characterized by: The following steps are involved: Treatment of excavation area: First, completely remove non-engineering soil within the scope of the project, such as grass, tree roots, etc., and use mechanized operation methods (such as bulldozers, loaders, hydraulic backhoes, etc.) for efficient excavation; Treatment of backfill area: Before backfilling, the backfill area should be thoroughly cleaned to remove impurities that are not conducive to soil compaction, and impact rolling test construction should be carried out; Dynamic tamping reinforcement treatment: After backfilling to the designed elevation, reserve the construction height of the geogrid, and then carry out dynamic tamping reinforcement; Over-excavation replacement cushion layer setting: After the earth and stone on the overlap surface are backfilled to the designed elevation, an over-excavation replacement cushion layer is set on the excavation side, with a total thickness of 1.5 meters, containing two layers of bidirectional geogrids, located at 0.5 meters and 1.0 meters respectively, and the grid backfill section is 1.0 meters; the strong tamping reinforcement on the fill side must be carried out before laying the geogrid; Engineering testing: The sand filling method is used to allow sand with uniform particles (or a single particle size) to fall freely from a certain height into a cylinder or hole of a specified volume. The volume of the test hole is measured based on the principle of constant unit mass, thereby inferring the density of the soil or pavement material.

2. A construction method for controlling differential settlement at the junction of excavation and filling of a field road foundation according to claim 1, characterized in that: In the excavation area processing steps, during the excavation process, if the inclination of the original terrain surface is consistent with the slope direction and the slope is steeper than 1:5, it is necessary to excavate into steps, and the step height is controlled according to the specifications.

3. A construction method for controlling differential settlement at the junction of excavation and filling of a field road foundation according to claim 1, characterized in that: In the filling area treatment steps, before backfilling, the cultivated soil, silt, humus, loose soil, loose soil, pumice and impurity soil in the backfill area should be thoroughly removed, and impact rolling test construction should be carried out to determine the layered paving thickness, number of rolling times and appropriate moisture content range to ensure the compaction effect.

4. A construction method for controlling differential settlement at the junction of excavation and filling of a field road foundation according to claim 1, characterized in that: In the dynamic tamping reinforcement treatment step, the treatment depth shall not be less than 5 meters, and a combination of two 2000KN.m spot tamping and one 1000KN.m full tamping is adopted. The thickness of the cushion layer shall be at least 1.0 meter.

5. The construction method for controlling differential settlement at the junction of excavation and filling of a field road foundation according to claim 1 is characterized by: In the step of setting up the over-excavation and replacement cushion layer, the over-excavation and replacement cushion layer adopts crushed stone soil filling material that meets the relevant technical requirements of earthwork engineering, and the maximum particle size of the crushed stone soil is required to be no more than 10cm, the gradation is good, and the solid volume ratio is not less than 83%.

6. A construction method for controlling differential settlement at the junction of excavation and filling of a field road foundation according to claim 1, characterized in that: In the engineering inspection step, the volume of the test hole is indirectly calculated by measuring a certain mass of sand falling freely from a fixed height into a container of known volume (such as a test hole). This volume is then used to represent the volume of the excavated soil or pavement material. Then, by comparing this volume with the mass of the volume of material, the density of the soil or pavement material can be calculated.

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