阅读说明：本技术 一种强夯联合固化处理湿陷性黄土路基的方法 (Method for treating collapsible loess subgrade through dynamic compaction and curing ) 是由 邓永锋 吴军 谈云志 于 2019-09-19 设计创作，主要内容包括：本发明公开了一种强夯联合固化处理湿陷性黄土路基的方法,把湿陷性黄土深部用强夯处理,强夯后的表层松土喷洒适量的高分子复合材料搅拌碾压,所用高分子复合材料由聚丙烯酰胺和石灰及水组成,其中石灰含量为30～40%,水的含量为59.99～69.98%,聚丙烯酰胺含量为0.005～0.02%。本发明将强夯和固化两种方法组合进行湿陷性黄土路基处理,使黄土的湿陷性、震陷性及液化势一次性消除,既提高了黄土路基处理效果,又降低了路基全部采用化学固化处理的高成本,从而系统解决工程的安全性与防灾减灾的有效性、耐久性。(The invention discloses a method for treating collapsible loess subgrade by combining dynamic compaction and solidification, which comprises the steps of carrying out dynamic compaction treatment on the deep part of collapsible loess, loosening the soil on the surface layer after dynamic compaction, spraying a proper amount of polymer composite material, stirring and rolling, wherein the polymer composite material consists of polyacrylamide, lime and water, the lime content is 30-40%, the water content is 59.99-69.98%, and the polyacrylamide content is 0.005-0.02%. The invention combines the dynamic compaction method and the solidification method to process the collapsible loess subgrade, so that the collapsible property, the seismic subsidence property and the liquefaction potential of the loess are eliminated at one time, thereby not only improving the processing effect of the loess subgrade, but also reducing the high cost of the subgrade which is completely processed by chemical solidification, and systematically solving the safety of the engineering, the effectiveness of disaster prevention and reduction and the durability of the disaster reduction.)

1. A method for treating collapsible loess subgrade by dynamic compaction combined curing is characterized by comprising the following steps:

1) trial tamping is carried out according to the properties of the loess and the regional experience, and then appropriate parameters are taken according to trial tamping results for dynamic tamping;

2) adding curing materials with different proportions according to the loess collapsibility degree to prepare polymer composite material slurry, and placing the polymer composite material slurry in a spraying kettle;

3) spraying a proper amount of polymer composite material after the loess on the surface layer is planed loose, and uniformly stirring in situ to obtain a modified loess layer;

4) rolling the road base by a vibratory roller;

5) and (5) after rolling, maintaining for 3-7 days, and performing the next procedure.

2. The method for treating collapsible loess subgrade by dynamic compaction combined curing according to claim 1, wherein the method comprises the following steps: the dynamic compaction single-stroke tamping energy in the step 1) is 5000-8000 kN.m, the distance between tamping points is 3.5-4.5 m, the tamping times are 2-3 times, the tamping intermittent time is 2-3 weeks, and the area of the hammer bottom is 4-6 m²。

3. The method for treating collapsible loess subgrade by dynamic compaction combined curing according to claim 1, wherein the method comprises the following steps: the polymer composite material in the step 2) is composed of polyacrylamide, lime and water, wherein the content of the lime is 30-40%, the content of the water is 59.99-69.98%, and the content of the polyacrylamide is 0.005-0.02%.

4. The method for treating collapsible loess subgrade by dynamic compaction combined curing according to claim 1, wherein the method comprises the following steps: the unit area dose of the sprayed polymer composite material in the step 3) is 1.5-1.8 kg/m²。

5. The method for treating collapsible loess subgrade by dynamic compaction combined curing according to claim 1, wherein the method comprises the following steps: the compacting machine in the step 4) is a vibratory roller with the vibration frequency of a steel wheel being 25-35 HZ, a straight line section is rolled from the road side to the road, and a curve section is rolled from the inner side to the outer side.

6. The method for treating collapsible loess subgrade by dynamic compaction combined curing according to claim 1, wherein the method comprises the following steps: in the rolling method in the step 4), after leveling the solidified loess on each construction section, a road roller is used for static pressing once, vibration rolling is carried out for 3-6 times, then static pressing is carried out once again, the rolling speed is controlled to be 3-4 km/h, and the row and row wheel distance overlap is 20-50 cm.

Technical Field

The invention relates to the technical field of treatment of subgrades in civil engineering and traffic and transportation engineering, in particular to a method for treating a collapsible loess subgrade by combining dynamic compaction and solidification.

Background

Loess is quaternary-piled, mainly fine soil particles, rich in carbonate, and has a macroporous yellow loose sediment. The characteristic that loess is soaked under certain pressure or water, the soil structure is rapidly destroyed and is remarkably sunk is the collapsibility of loess. Loess has collapsible property, which causes uneven settlement of roadbed and influences the strength and stability of road. The construction in the collapsible loess area often has diseases related to the collapsible loess area. The construction of high-grade highway subgrade in loess areas is one of the problems that need attention.

Throughout the current research situation at home and abroad, the current common treatment methods for collapsible loess subgrades comprise measures such as a cushion method, a lime-soil pile, a cement-soil pile, a CFG pile, a chemical strengthening method, dynamic compaction and the like. The bedding method is suitable for treatment of small area above underground water level, and the thickness of the soil layer is 1-3 m. The method for compacting the lime-soil piles can effectively eliminate the collapsibility of loess, the treatment depth is generally 5-15 m, but the soil layer to be treated is required to be above the underground water level, and the water content is 14-23%; the CFG pile method is applied to the treatment of the loess foundation of the building construction engineering, but most aims at the non-collapsible loess foundation; the chemical reinforcement method relies on the curing agent to produce gel to glue loose particles into a whole to improve the strength of the loess, reduce the water permeability and eliminate the collapsibility, has good effect, but has high chemical component cost and is not suitable for large-scale application. The dynamic compaction method is widely used for treating the collapsible loess subgrade, is suitable for the collapsible loess with the saturation degree less than or equal to 60% above the underground water level, has the treatable soil layer thickness of 3-12 m, and compacts the soil body through the free falling of the heavy hammer so as to improve the soil body strength and reduce the compressibility of the soil body. The method has the advantages of simple construction equipment, investment saving, wide application, intuitive principle and obvious reinforcement effect on unsaturated soil. However, the strong ramming method for processing the loess subgrade has the outstanding problems that the subgrade cannot be waterproof, and engineering measures combining water proofing and drainage are required, so that the use of the loess subgrade is limited.

Aiming at the current situation that the water resistance, the shock resistance and the dynamic property of the subgrade treated by the dynamic compaction method are poor. If deep collapsible loess is treated by dynamic compaction, and the surface layer is sprayed with curing material and stirred and tamped, the two methods are combined, so that the collapsible property, the shock resistance and the liquefaction potential of the loess are eliminated, the roadbed treatment effect is improved, and the cost is lower than that of a chemical reinforcement method. Therefore, the tamping solidification method is a design concept that the dynamic compaction method and the chemical strengthening method are combined to play the comprehensive role of the dynamic compaction method and the chemical strengthening method.

Disclosure of Invention

In order to solve the problems, the invention discloses a method for treating the collapsible loess subgrade by combining dynamic compaction and solidification, which has the advantages of reasonable technology, controllable quality, capability of prolonging the service life of a project and effectively controlling the cost, and is a collapsible loess subgrade treatment mode with both project applicability and economy.

In order to achieve the above purpose, the invention provides the following technical scheme:

a method for treating collapsible loess subgrade by dynamic compaction combined curing comprises the following steps:

1) trial tamping is carried out according to the properties of the loess and the regional experience, and then appropriate parameters are taken according to trial tamping results for dynamic tamping;

2) adding curing materials with different proportions according to the loess collapsibility degree to prepare polymer composite material slurry, and placing the polymer composite material slurry in a spraying kettle;

3) spraying a proper amount of polymer composite material after the loess on the surface layer is planed loose, and uniformly stirring in situ to obtain a modified loess layer;

4) rolling the road base by a vibratory roller;

5) and (5) after rolling, maintaining for 3-7 days, and performing the next procedure.

Further, the dynamic compaction single-stroke tamping energy in the step 1) is 5000-8000 kN.m, the distance between tamping points is 3.5-4.5 m, the tamping times are 2-3 times, the tamping intermittent time is 2-3 weeks, and the area of the hammer bottom is 4-6 m²。

Further, the polymer composite material in the step 2) is composed of polyacrylamide, lime and water, wherein the content of the lime is 30-40%, the content of the water is 59.99-69.98%, and the content of the polyacrylamide is 0.005-0.02%.

Further, the unit area dosage of the sprayed polymer composite material in the step 3)1.5 to 1.8kg/m²。

Further, the compacting machine in the step 4) is a vibratory roller with the vibration frequency of a steel wheel being 25-35 HZ, the straight line section is rolled from the roadside to the road, and the curve section is rolled from the inner side to the outer side.

Further, the rolling method in the step 4) is that after the solidified loess on each construction section is flattened, a road roller is used for static pressing once, vibration rolling is carried out for 3-6 times, then static pressing is carried out again, the rolling speed is controlled to be 3-4 km/h, and the overlapping distance between the rows and the tracks is 20-50 cm.

Compared with the prior art, the invention has the beneficial effects that:

1. the dynamic compaction method and the polymer composite material curing method are combined together, the advantages of the two methods are exerted simultaneously, the technology is reasonable, the functional requirements are met, and certain innovativeness is achieved;

2. the dynamic compaction curing method can thoroughly treat the collapsible loess subgrade, thereby not only eliminating the collapsible property, the shock resistance and the liquefaction potential of the loess, but also greatly reducing the later-period maintenance cost;

3. the service life of the roadbed engineering can be obviously prolonged;

4. the material is environment-friendly and convenient to operate.

Drawings

Fig. 1 is a process flow diagram of a method for treating collapsible loess subgrade by dynamic compaction combined curing.

Fig. 2 is a schematic diagram of the waterproof function of the collapsible loess subgrade treated by dynamic compaction and curing in combination with the dynamic compaction.

Detailed Description

The present invention will be further illustrated with reference to the accompanying drawings and specific embodiments, which are to be understood as merely illustrative of the invention and not as limiting the scope of the invention.

As shown in the figure, the invention provides a method for treating collapsible loess subgrade by combining dynamic compaction and curing, wherein the deep part of the collapsible loess is treated by the dynamic compaction, the loose soil on the surface layer after the dynamic compaction is sprayed with a proper amount of polymer composite material for stirring and rolling, and the dynamic compaction and the curing are combined for treating the collapsible loess subgrade, so that the collapsible property, the seismic subsidence and the liquefaction potential of the loess are eliminated at one time, the loess subgrade treatment effect is improved, the high cost of chemical curing treatment adopted by the subgrade is reduced, the safety of the engineering and the effectiveness and durability of disaster prevention and reduction are systematically solved, and the method can be popularized to the improvement of other types of special foundations and subgrades with high requirements on water stability.