CN112627154B

CN112627154B - Water network zone lime solidified soil test section filling design method

Info

Publication number: CN112627154B
Application number: CN202011486433.4A
Authority: CN
Inventors: 周联英; 陈�峰; 高建科; 刘铁男; 孙苗苗; 张茹
Original assignee: Zhejiang University City College ZUCC
Current assignee: Zhejiang University City College ZUCC
Priority date: 2020-12-16
Filing date: 2020-12-16
Publication date: 2022-02-11
Anticipated expiration: 2040-12-16
Also published as: CN112627154A

Abstract

The invention relates to a method for designing filling of a lime solidified soil test section of a water network zone, which comprises the following steps: step S1, designing the mixing proportion of the doped ash: firstly, according to the water content of the slurry dried soil, carrying out corresponding ash mixing amount mixing ratio design, mixing ash twice, mixing quicklime blocks for the first time, turning and stirring the mixture, crushing for the second time, mixing ash for the second time, and mixing and discharging by adopting a forced mixer; step S2, paving and rolling; step S3, maintenance and detection: when the filling between the solidified soil embankment layers is continuously carried out, no additional maintenance is required. The invention has the beneficial effects that: the first and second layers of the solidified soil embankment in the water network zone adopt the processes of dumping and unloading in a loaded area, super-thick filling and cement curing agent doping, so that the bottom roadbed can be smoothly filled; and the third layer begins to adopt a spreading process of a spreading machine, so that the environmental pollution caused by road mixing and dust doping can be avoided, and the work efficiency, the roadbed flatness and other qualities are obviously improved.

Description

Water network zone lime solidified soil test section filling design method

Technical Field

The invention relates to a filling process of slurry solidified soil, in particular to a filling design method of a water network zone lime solidified soil test section.

Background

In recent years, a large amount of waste slurry is generated in engineering construction, a large amount of land resources are required to be occupied for fixed-point consumption, and even greater environmental pollution can be caused. With the rapid development of the slurry solid-liquid separation technology, such as a centrifugal method, a filter pressing method and the like, the water content of the separated slurry residue soil (slurry dried soil) can be reduced to about 35 percent, and the possibility is provided for the utilization of the residue soil. Meanwhile, the slag used as the traditional roadbed filling in Zhejiang province has increasingly scarce material sources along with the restriction of government on mountain mining, and the gap of high-quality material sources required by roadbed filling in various places is increasingly large. Therefore, the slurry dried soil is solidified by adopting lime and cement and then used as roadbed filling, and the method has great significance. Particularly, the water network zone in Zhejiang river has high underground water level and high requirement on the water stability of the roadbed filler, and the research on the filling process of the slurry solidified soil is more beneficial to the popularization and application of the slurry solidified soil.

Disclosure of Invention

The invention aims to solve the defects of difficult construction of a roadbed bottom layer, poor water stability and the like in the existing lime soil filling technology of a water network zone, and provides a water network zone lime solidified soil test section filling design method.

The method for designing the filling of the lime-solidified soil test section of the water network zone comprises the following steps:

step S1, design of ash blending proportion

Firstly, according to the water content (generally between 30-40%) of the sludge dried soil (mud cake), carrying out corresponding ash mixing amount mixing ratio design, mixing ash twice, mixing quicklime blocks for the first time, stirring and stewing the material, crushing the material for the second time, mixing ash for the second time, and adopting a forced mixer to mix and discharge the material; the mixing proportion design of the doped ash is as follows: when the moisture content of the dried soil is larger (35-40%), adding quicklime blocks 4-5% or 3-4% for the first time in the field; when the water content of the dried soil is between 30 and 35 percent, adding 3 to 4 percent or 2 to 3 percent of quicklime blocks for the first time in the field; namely, the first ash mixing amount is determined by the water content and the time limit (material stewing time); when the water content of the first ash-doped stewing material is reduced to be capable of being conveyed by a conveying belt, the crushing process is carried out twice, then the second ash doping is carried out, and the ground raw ash powder is doped and grinded by 2-3%.

Step S2, paving and rolling process

Step S2-1, considering that the water network zone foundation is generally weak, and paving and rolling equipment is easy to cause the phenomenon of roadbed springs when the first layer of embankment bottom is filled, a material transporting vehicle is provided to back into the field along the filling direction to discharge super-thick filling test section method, which is used for the first and second layers of embankment filling; namely the loose paving thickness of the first layer of the filler is 60-65cm, the loose paving thickness of the second layer is 45-50cm, a grid method is adopted, a material transporting vehicle backs from the paved material to enter a field for unloading and leave the field, and a bulldozer is adopted for primary leveling and a grader is adopted for fine leveling, and the process is shown in figure 1.

And step S2-2, when the third layer and the above layers are filled, a paver paving process is adopted, so that the paving thickness uniformity and the surface flatness are improved, and the construction efficiency is improved. Because the paver is generally used for paving the water-stable asphalt pavement of the road surface, and the lime soil is loose material, when the conventional paver is adopted for paving, because the paver is limited by the amplitude of the screed and the frequency of the vibrating beam, the effect of preliminary rolling is difficult to play when the paver is paved, and when the subsequent road roller is rolled, the loose material is easy to push, so that the poor leveling phenomenon is caused. Therefore, the conventional paver needs to be modified, the amplitude of the screed plate is increased, and the frequency of the vibrating beam is adjusted, so that the effect of primary rolling during the lime soil paving is achieved, and the work efficiency and the flatness are improved.

And step S2-3, the lime-soil rolling adopts the conventional processes of firstly static pressing, steel wheel vibration rolling and smooth wheel surface rolling. And carrying out rolling construction of a test section.

And S2-4, selecting a typical section when the length of the section of the test section is not less than 150m, filling the section from the roadbed bottom to the roadbed top for construction of the test section, and performing corresponding deflection detection when each layer is finished.

Step S3, maintenance and detection: when the filling between the solidified soil embankment layers is continuously carried out, no additional maintenance is required; the test section adopts interval pavement, and after the lower filling is finished, the covering geotextile is adopted, and the compactness detection and the deflection detection are carried out after the watering, moisturizing and curing are carried out for 7 days.

Preferably, the method comprises the following steps: in the step S1, when the water content of the dried soil is 35-40%, stewing is carried out for 2-4 days if the content of the quicklime blocks doped for the first time is 4-5%, and stewing is carried out for 5-7 days if the content of the quicklime blocks doped for the first time is 3-4%; when the water content of the dried soil is 30-35%, stewing for 2-4 days if the content of the quicklime blocks doped for the first time is 3-4%, and stewing for 5-7 days if the content of the quicklime blocks doped for the first time is 2-3%.

Preferably, the method comprises the following steps: in step S1, when the lime-soil is used for filling the first layer of the embankment in the water network zone, it is required to add 3.5-4% cement (the second layer depends on the environment) during the second time of lime mixing, and it is required to complete the rolling of the roadbed before the cement is initially set. The ash blending ratio is designed as shown in table 1:

TABLE 1 Graded mixing ratio design

Preferably, the method comprises the following steps: in the step S2-3, through construction of a test section, rolling combination process parameters of a 93 area (1.5 m below the top surface of the roadbed), a 94 area (0.8-1.5 m below the top surface of the roadbed) and a 96 area (0-0.8 m below the top surface of the roadbed) of a first-level highway all-line construction section are obtained. If the test section is limited (the filling height does not include the 93 areas), the 94 areas are used for firstly carrying out the road roller mechanical rolling combined technological parameter test of the 93 areas (starting from the third time of vibration rolling, the rolling degree is checked at each time of rolling to obtain the rolling times of the 93 areas), and then carrying out the technological parameter test of the 94 areas (the rolling times are increased continuously, the rolling degree is checked at each time of rolling one layer, and the rolling degree meets the requirement). According to the scheme of the test section, the first layer of the roadbed is filled with super-thick filling (the loose pavement thickness reaches 65cm), so that rolling equipment with matched compaction work needs to be selected or the rolling times are increased through vibration. When the first layer compactness detection and the second layer compactness detection are carried out by adopting a cutting ring method, the cutting ring is required to penetrate through the whole filling thickness, and the substrate compactness is taken as the evaluation index of the layer.

The invention has the beneficial effects that:

1. the slurry dried soil is solidified to be used as roadbed filler, so that the slurry dried soil has the advantages of good integrity after hardening, light dead weight and the like, can reduce diseases such as uneven settlement of a roadbed and the like, and has remarkable social and economic benefits.

2. The first and second layers of the solidified soil embankment in the water network zone adopt the processes of dumping and unloading in a loaded area, super-thick filling and cement curing agent doping, so that the bottom roadbed can be smoothly filled; and the third layer begins to adopt a spreading process of a spreading machine, so that the environmental pollution caused by road mixing and dust doping can be avoided, the quality such as work efficiency, roadbed flatness and the like is obviously improved, the environment protection, energy conservation, high efficiency and obvious economic and social benefits are really achieved.

3. The invention adopts the paver to pave, effectively improves the flatness and compactness of the pavement, integrates paving, leveling and jolt ramming, reduces the labor burden of constructors, reduces the capital investment and realizes multiple purposes of one machine.

Drawings

FIG. 1 is a schematic view of a bulldozer for dumping solidified soil of a first layer and a second layer for paving;

FIG. 2 is a flow chart of the construction process of the present invention.

Detailed Description

The present invention will be further described with reference to the following examples. The following examples are set forth merely to aid in the understanding of the invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

As an embodiment, the water network zone lime solidified soil test section filling design method comprises the following steps:

the method comprises the following steps: and (6) clearing the site. Selecting a typical section as a test section, and cleaning the site according to design requirements and highway subgrade construction technical specifications. The method is characterized in that humus soil, surface soil, turf and the like on the surface layer of the original ground within the range of the road width are cleaned, and tree roots within the range of the subgrade base are leveled and compacted according to design requirements after all the tree roots are excavated.

Step two: and (6) measuring and lofting. After the site is cleaned, after various technical indexes such as compactness, flatness, cross slope and the like are inspected to be qualified, side piles are determined and filling side lines of the roadbed are determined by measuring personnel, and a gray line grid is formed on the first layer of the roadbed and used for discharging solidified soil in a grid mode.

Step three: and (5) intensively mixing the solidified soil. For the high-water-content soil source, the ash-mixing and material-stewing process shown in the table 1 needs to be carried out to reduce the water content, the soil is crushed by a crusher and then enters a weighing machine for weighing and metering, and finally the soil is uniformly mixed in a mixing plant through a forced mixer and ground quicklime (2% -3%) to wait for loading.

Step four: and (5) carrying out totally-enclosed transportation. In order to protect the environment, reduce the dust emission and control the optimal water content of the solidified soil, the solidified soil is transported in a totally-enclosed way by adopting a green-case type muck truck from the factory to the site. And when the vehicle is transported to a construction site for more than 4 hours, the vehicle is discarded.

Step five: and (6) paving on the spot. Before paving, the surface of the lower bearing layer is cleaned and sprayed with water for wetting. When the first and second layers of solidified soil are constructed in water network area, the first layer of solidified soil is mixed with 3.5-4% cement to raise the strength and water stability of road bed. The first and second layers of solidified soil are filled by adopting a grid method, and a material transporting vehicle pours in and unloads materials (as shown in figure 1) in a loaded area, and the construction processes of primary leveling of a soil piling machine and fine leveling of a land leveler are carried out; the second layer of solidified soil is filled by adopting a grid method, and whether cement needs to be added into the mixture depends on the height of the underground water level; and starting the third layer, and adopting a paver to pave and a grader to finish the construction process in order to improve the uniformity of the paving thickness and the flatness of the top layer of the pavement. When the paver paves the solidified soil, the walking speed is controlled to be 2.5-3.5m/min, the vibration amplitude of the screed plate is increased, and the frequency of the vibrating beam is set to be close to the natural frequency of the mixture, so that the mixture can have higher initial compaction degree, and the continuous and reliable operation of the paver can be ensured.

Step six: and (5) rolling and forming. And the solidified soil is rolled in time after being flattened and shaped, and the condition that the soil is firstly light and then heavy, and is firstly slow and then fast is followed, so that the uniform rolling is ensured. The first layer is statically pressed for 1 time by a 22t steel wheel, then the 22t steel wheel is vibrated and rolled for 4 times to a region 93, a region 6 to a region 94 and a region 9 to a region 96, and finally a double-steel-wheel road roller is adopted for rolling for 4 times to perform surface folding reinforcement, so that the lamination compactness is greater than the specified compactness. Because the filling is carried out in the water network zone, the filling thickness is larger, if the filling thickness of the test section cannot meet the requirements of the whole section and the construction of the whole section needs to be guided due to the limitation of construction conditions, the 94 area can be used for obtaining the 93 area test data.

Step seven: and (5) maintaining and detecting. The solidified soil embankment is paved at intervals, after one layer of solidified soil is paved, the solidified soil is covered with geotextile, the solidified soil cannot be over-wet or even dry or over-wet during the curing period, other vehicles are strictly forbidden to enter except for watering vehicles, and the compactness and deflection detection is carried out 7 days after the watering, moisturizing and curing. The compaction degree is detected by adopting a cutting ring method, and because the water network zone is filled thickly, the cutting ring needs to be taken into a deeper part, and the compaction result is distorted when the driving depth is shallow. The deflection test adopts a Beckman beam method to measure simultaneously on both sides, the integral bearing capacity of the test piece is evaluated, and the deflection detection result meets the acceptance requirement.

Claims

1. A water network zone lime solidified soil test section filling design method is characterized by comprising the following steps:

step S1, design of ash blending proportion

Firstly, according to the water content of the slurry drying soil, carrying out corresponding ash mixing proportion design, mixing ash twice, mixing quicklime blocks for the first time, turning and stirring the mixture, crushing for the second time, mixing ash for the second time, and mixing and discharging by adopting a forced mixer; the mixing proportion design of the doped ash is as follows: when the water content of the dried soil is more than or equal to 35% and less than or equal to 40%, stewing for 2-4 days if quicklime blocks are mixed for the first time in the field more than or equal to 4% and less than or equal to 5%, stewing for 5-7 days if quicklime blocks are mixed for the first time in the field more than or equal to 3% and less than 4%; when the water content of the dried soil is more than or equal to 30% and less than 35%, stewing for 2-4 days if quicklime blocks are mixed for the first time in the field more than or equal to 3% and less than or equal to 4%, stewing for 5-7 days if quicklime blocks are mixed for the first time in the field more than or equal to 2% and less than 3%; when the water content of the first ash-doped stewing material is reduced to be capable of being conveyed by a conveyer belt, carrying out crushing twice, then carrying out second ash doping, and milling to form 2% -3% of ash-generating powder; when the lime soil is used for filling the first layer of the embankment of the water network zone, adding 3.5-4% of cement during the second time of lime mixing, and finishing roadbed rolling before the initial setting of the cement;

step S2, paving and rolling process

Step S2-1, adopting a method that a material transporting vehicle backs up to the field along the filling direction to unload the super-thick filling test section to carry out first and second layers of filling of the embankment; the loose paving thickness of the first layer of the filler is 60-65cm, the loose paving thickness of the second layer is 45-50cm, a grid method is adopted, a material conveying vehicle backs from the paved material to enter a field for unloading and leave the field, and a bulldozer is adopted for primary leveling and a grader is adopted for fine leveling;

s2-2, when filling the third and above layers, adopting a paver to pave and a grader to finish the construction process; the conventional paver is modified, the amplitude of the screed is increased, and the frequency of the vibrating beam is adjusted to be close to the natural frequency of the filler, so that the effect of primary rolling during the lime soil paving is achieved;

step S2-3, the lime-soil rolling adopts the processes of first static pressure, then steel wheel vibration rolling and smooth wheel rolling; carrying out rolling construction of a test section; acquiring rolling combination process parameters of 93 zones, 94 zones and 96 zones of a first-level highway all-line construction section through test section construction; if limited by construction conditions, the filling thickness of the test section cannot meet the requirement of the whole section, and the construction of the whole section needs to be guided, a road roller mechanical rolling combined process parameter test of the 93 sections is firstly carried out by utilizing the 94 section, the rolling times of the 93 sections are obtained by rolling once and checking the compaction degree, starting from the third vibration rolling, then the process parameter test of the 94 section is carried out on the basis, the rolling times are continuously increased, and the compaction degree is checked randomly for each layer of rolling until the compaction degree meets the requirement;

s2-4, selecting a typical section when the length of the section of the test section is not less than 150m, filling the typical section from the roadbed bottom to the roadbed top for construction of the test section, and performing corresponding deflection detection when each layer is completed;

step S3, maintenance and detection: the test section adopts interval pavement, after the lower layer is filled, the covering geotextile is adopted, and the compactness detection and the deflection detection are carried out after the watering, moisturizing and curing are carried out for 7 days; when the first layer compactness detection and the second layer compactness detection are carried out by adopting a cutting ring method, the cutting ring penetrates through the whole filling thickness, and the substrate compactness is taken as the evaluation index of the layer.