Method for treating Yellow River downstream alluvial silt foundation through resonance compaction method

Abstract

The invention provides a method for treating a Yellow River downstream alluvial silt foundation through a resonance compaction method, and the method comprises the following steps: carrying out geological investigation on the Yellow River downstream alluvial silt foundation, and selecting proper resonance compaction equipment; positioning the resonance compaction equipment according to a preset interval and an arrangement mode; the resonance compacting equipment is started, and resonance compacting treatment is conducted on the foundation point by point according to set parameters; in the resonance compaction construction process, the resonance frequency of a vibration hammer-vibration rod-foundation soil system is monitored all the time; after foundation treatment is completed, an in-situ testing method and the like are adopted for detecting the foundation, and long-term monitoring is conducted on foundation settlement in the upper building construction and using process. According to the method, the resonance principle can be effectively utilized to rearrange silt particles, pores are reduced, the compactness and liquefaction resistance of foundation soil are improved, and the method has the advantages of being high in construction efficiency, low in cost, small in influence on the surrounding environment and the like.

Description

Technical Field

[0001] The invention relates to the technical field of foundation treatment, in particular to a method for treating alluvial silt foundation in the lower reaches of the Yellow River by a resonance compaction method. Background Art

[0002] The alluvial plain in the lower reaches of the Yellow River is widely distributed with sedimentary soils mainly composed of silt and silty sand. Compared with ordinary silt, these sedimentary soils have the characteristics of high silt content, poor gradation, intense capillary action, poor water stability, and high particle roundness. Moreover, these sedimentary soils are newly formed underconsolidated soils with loose structure and low shear strength, which are poor foundations for engineering construction. When carrying out engineering construction on the alluvial silt foundation in the lower reaches of the Yellow River, if it is not effectively treated, it will lead to problems such as excessive settlement, tilting, and even destruction of the building. Traditional foundation treatment methods such as the crushed stone pile method require a large amount of gravel and crushed stone fillers, which are expensive; the dynamic compaction method has a limited treatment depth, and its vibration has a great impact on the surrounding environment; the compaction pile method has a serious environmental pollution and also has the problem of high cost; the replacement method has a very limited treatment depth, usually not exceeding 3m. Therefore, an efficient, economical and environmentally friendly alluvial silt foundation treatment method in the lower reaches of the Yellow River is needed.

[0003] Secondly, as a new type of foundation treatment technology, the resonance compaction method has unique advantages in treating alluvial silt foundations in the lower reaches of the Yellow River. However, there is currently a lack of a systematic and complete method for the application of the resonance compaction method based on the characteristics of alluvial silt foundations in the lower reaches of the Yellow River. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies of the prior art, the present invention provides a method for treating alluvial silt foundation in the lower reaches of the Yellow River by a resonance compaction method, which solves the problems raised by the above-mentioned background technology.

[0006] (II) Technical solution

[0007] To achieve the above purpose, the present invention is implemented by the following technical scheme: a method for treating alluvial silt foundation in the lower reaches of the Yellow River by resonance compaction method, comprising the following steps:

[0008] Step 1: Preliminary investigation and preparation:

[0009] Conduct geological surveys on the alluvial silt foundation in the lower reaches of the Yellow River, measure the physical and mechanical parameters of the silt, calculate the natural frequency range of the foundation soil, and select appropriate resonance compaction equipment;

[0010] Step 2: Site leveling and equipment positioning:

[0011] Clear the surface debris, garbage and soft soil layers of the foundation site to be treated in the lower reaches of the Yellow River to make the site level; position the resonance compaction equipment according to the predetermined spacing and arrangement, and adjust the height and levelness of the equipment so that the vibration rod is perpendicular to the foundation soil and the equipment is stable;

[0012] Step 3: Resonance dense implementation:

[0013] Start the resonance compaction equipment and perform resonance compaction on the foundation point by point according to the set parameters. The resonance compaction time for each construction point is 20-30 minutes. At the same time, observe the reaction of the foundation soil. If there is any abnormality, adjust the parameters in time or stop the construction process;

[0014] Step 4: Quality Inspection:

[0015] During the resonance compaction process, the resonance frequency of the "vibration hammer-vibration rod-foundation soil" system is monitored at all times, and the vibration parameters are adjusted in time according to the monitoring results. When the density of the foundation soil meets the design requirements, the equipment is stopped and a comprehensive quality assessment is carried out;

[0016] Step 5: Long-term monitoring of foundation settlement:

[0017] After the foundation treatment is completed, the foundation settlement is monitored over a long period of time during the construction and use of the upper building, and corresponding reinforcement measures are taken based on the monitoring results.

[0018] Preferably, in step one, the resonant compaction equipment includes a vibrating hammer with adjustable frequency and amplitude, a counterweight system and a control system, the frequency adjustment range of the vibrating hammer covers the calculated natural frequency range, and the amplitude adjustment range of the vibrating hammer is determined according to the density requirement of the silty soil foundation.

[0019] Preferably, step two also includes measuring and laying out on the leveled site according to design requirements, determining the area range and construction points for resonance compaction treatment, and dividing the foundation to be treated into layers, with each layer having a thickness of 0.5-1.5 meters.

[0020] Preferably, in step three, after starting the resonance compaction equipment, the vibration rod is first penetrated to the designed depth with a higher frequency and a smaller amplitude, and then the frequency of the "vibration hammer-vibration rod" is gradually adjusted to resonate with the natural frequency of the foundation soil. The resonance state is judged by the vibration acceleration, and the resonance is maintained for 1-3 minutes, and then the vibration rod is lifted to the ground; during the resonance process, the vibration frequency is adjusted in time according to the compaction condition of the foundation soil.

[0021] Preferably, in step 4, the quality of the treated foundation soil is tested by in-situ testing methods and indoor geotechnical tests, and whether the design requirements are met is determined based on the test results, and unqualified areas are reworked until they meet the requirements.

[0022] Preferably, the in-situ testing method includes a pore pressure static penetration test and a standard penetration test, and the indoor geotechnical test includes the determination of density, water content, void ratio, and shear strength index.

[0023] (III) Beneficial effects

[0024] The present invention provides a method for treating the alluvial silt foundation in the lower reaches of the Yellow River by a resonance compaction method, which has the following characteristics:

[0025] Beneficial effects:

[0026] 1. The present invention can effectively utilize the resonance principle to rearrange the silt particles and reduce the pores, thereby improving the density and liquefaction resistance of the foundation soil. It has the advantages of high construction efficiency, low cost, and little impact on the surrounding environment. It has broad application prospects in the foundation treatment project in the lower reaches of the Yellow River.

[0027] 2. According to the characteristics of alluvial silt foundation in the lower reaches of the Yellow River, it can effectively improve the density and anti-liquefaction ability of the foundation through reasonable construction steps and parameter control, reduce the occurrence of foundation settlement and liquefaction and other problems, and has significant engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0029] 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.

[0030] Embodiment 1:

[0031] like Figure 1 As shown, the embodiment of the present invention provides a method for treating the alluvial silt foundation in the lower reaches of the Yellow River by a resonance compaction method, comprising the following steps:

[0032] Step 1: Preliminary investigation and preparation:

[0033] Conduct geological surveys on the alluvial silt foundation in the lower reaches of the Yellow River, determine the physical and mechanical parameters of the silt, calculate the natural frequency range of the foundation soil, and select appropriate resonance compaction equipment. Specifically, the resonance compaction equipment includes a vibrating hammer with adjustable frequency and amplitude, a counterweight system, and a control system. The frequency adjustment range of the vibrating hammer in the lower reaches of the Yellow River covers the calculated natural frequency range, and the amplitude adjustment range of the vibrating hammer is determined according to the density requirements of the silt foundation.

[0034] Step 2: Site leveling and equipment positioning:

[0035] Remove the surface debris, garbage and soft soil layers of the foundation site to be treated to make the site level; then measure and lay out on the leveled site according to the design requirements, determine the area range and construction points for resonance compaction treatment, and divide the foundation to be treated into layers, with each layer being 0.5 meters thick; position the resonance compaction equipment according to the predetermined spacing and arrangement, and adjust the height and levelness of the equipment so that the vibration rod acts vertically on the foundation soil and the equipment is stable;

[0036] Step 3: Resonance dense implementation:

[0037] Start the resonance compaction equipment, and perform resonance compaction on the foundation point by point according to the set parameters. The resonance compaction time for each construction point is 20 minutes. Specifically, after starting the resonance compaction equipment, first penetrate the vibrating rod with a higher frequency and a smaller amplitude to the designed depth, and then gradually adjust the frequency of the "vibrating hammer-vibrating rod" to resonate with the natural frequency of the foundation soil. The resonance state is determined by the vibration acceleration, and the resonance is maintained for 1 minute, and then the vibrating rod is lifted to the ground; during the resonance process, the vibration frequency is adjusted in time according to the compaction condition of the foundation soil;

[0038] Step 4: Quality Inspection:

[0039] During the resonant compaction construction process, the resonant frequency of the "vibratory hammer-vibrating rod-foundation soil" system is monitored at all times, and the vibration parameters are adjusted in time according to the monitoring results. When the density of the foundation soil reaches the design requirements, the equipment is stopped and a comprehensive quality assessment is carried out. Specifically, the quality of the treated foundation soil is tested by in-situ testing methods and indoor geotechnical tests, wherein the in-situ testing methods include pore pressure static penetration tests and standard penetration tests, and the indoor geotechnical tests include density, water content, porosity, and shear strength index determination. Whether the design requirements are met is judged based on the test results, and the unqualified areas are reworked until they meet the requirements;

[0040] Step 5: Long-term monitoring of foundation settlement:

[0041] After the foundation treatment is completed, the foundation settlement is monitored over a long period of time during the construction and use of the upper building, and corresponding reinforcement measures are taken based on the monitoring results.

[0042] Embodiment 2:

[0043] The difference between this embodiment and the first embodiment is that: in step 2, the surface debris, garbage and soft soil layer of the foundation site to be treated in the lower reaches of the Yellow River are cleared to make the site level; then, according to the design requirements, measurements and layout are carried out on the leveled site to determine the area range and construction points for resonance compaction treatment, and the foundation to be treated is layered, with each layer being 1.0 meter thick; the resonance compaction equipment is positioned according to a predetermined spacing and arrangement, and the height and levelness of the equipment are adjusted so that the resonator acts vertically on the foundation soil and the equipment is stable.

[0044] In step three, start the resonance compaction equipment, and perform resonance compaction on the foundation point by point according to the set parameters. The resonance compaction time for each construction point is 25 minutes. Specifically, after starting the resonance compaction equipment, first penetrate the vibrating rod to the designed depth with a higher frequency and a smaller amplitude, and then gradually adjust the frequency of the "vibrating hammer-vibrating rod" to resonate with the natural frequency of the foundation soil. The resonance state is judged by the vibration acceleration, and the resonance is maintained for 2 minutes, and then the vibrating rod is lifted to the ground; during the resonance process, the vibration frequency is adjusted in time according to the compaction condition of the foundation soil.

[0045] Embodiment three:

[0046] The difference between this embodiment and embodiment one is that: in step two, the surface debris, garbage and soft soil layers of the foundation site to be treated in the lower reaches of the Yellow River are cleared to make the site level; then, according to the design requirements, measurements and layout are carried out on the leveled site to determine the area range and construction points for resonance compaction treatment, and the foundation to be treated is layered, with each layer being 1.5 meters thick; the resonance compaction equipment is positioned according to a predetermined spacing and arrangement, and the height and levelness of the equipment are adjusted so that the resonator acts vertically on the foundation soil and the equipment is stable.

[0047] In step three, start the resonance compaction equipment, and perform resonance compaction on the foundation point by point according to the set parameters. The resonance compaction time for each construction point is 30 minutes. Specifically, after starting the resonance compaction equipment, first penetrate the vibrating rod to the designed depth with a higher frequency and a smaller amplitude, and then gradually adjust the frequency of the "vibrating hammer-vibrating rod" to resonate with the natural frequency of the foundation soil. The resonance state is judged by the vibration acceleration, and the resonance is maintained for 3 minutes, and then the vibrating rod is lifted to the ground; during the resonance process, the vibration frequency is adjusted in time according to the compaction condition of the foundation soil.

[0048] Experimental Example 1:

[0049] In a certain Yellow River downstream project, the site was first leveled, weeds, old building foundations and other debris in the site were cleared, and then measurement and laying out were carried out to determine that the resonance compaction construction area was 100m long and 50m wide, and a total of 30 construction sites were divided. The resonance compaction equipment was hoisted to the first construction site. According to the geological survey report of the area, the resonance frequency was set to 25Hz, the amplitude was set to 10mm, the exciting force was set to 30kN, and the equipment was started to carry out resonance compaction construction. The construction time was 60min. During the construction process, no abnormal phenomenon was found in the foundation soil. After completing the construction of this point, the same operation was performed on other points in turn. After all the construction was completed, quality inspection was carried out. The standard penetration test results showed that the density of the foundation soil was significantly improved before treatment. The indoor geotechnical test results also showed that the water content was reduced, the porosity was reduced, and the shear strength was increased. All indicators met the design requirements, indicating that the resonance compaction method of the present invention has achieved good results in the treatment of alluvial silt foundation in the lower reaches of the Yellow River.

[0050] In summary, the resonance compaction method of the present invention for treating alluvial silt foundation in the lower reaches of the Yellow River can effectively utilize the resonance principle to rearrange the silt particles and reduce the pores, thereby improving the density and liquefaction resistance of the foundation soil. It has the advantages of high construction efficiency, low cost, and little impact on the surrounding environment. It has broad application prospects in foundation treatment projects in the lower reaches of the Yellow River.

[0051] Experimental Example 2:

[0052] At a construction site in the lower reaches of the Yellow River, an investigation showed that the silt foundation contained about 60% silt, a porosity of 0.55, a water content of 20%, a groundwater level of 3 meters, a shear strength of 15 kPa, and a compression modulus of 8 MPa.

[0053] First, based on these parameters, the natural frequency range of the foundation soil is calculated to be approximately 15-25Hz. A resonant compaction machine with a vibrator frequency adjustment range of 10-30Hz and an amplitude adjustment range of 3-10mm is selected.

[0054] Then, the construction site is leveled, the deviation is controlled within ±5cm, and the resonance compaction equipment is evenly arranged in the foundation treatment area at intervals of 2 meters.

[0055] Start the equipment and pre-vibrate it at a frequency of 10 Hz and an amplitude of 3 mm for 8 minutes. Then gradually increase the frequency. When the frequency reaches 20 Hz, it is observed that the vibration acceleration reaches a maximum value and stabilizes. At this time, it is in a resonant state. Maintain the resonance for 15 minutes and adjust the amplitude to 6 mm during the resonance process.

[0056] During the resonance process, a standard penetration test is carried out every 5 minutes to check the density. When three consecutive test results show that the density meets the design requirements, the equipment is stopped.

[0057] Finally, the bearing capacity and settlement characteristics of the treated foundation were evaluated, and the results showed that it met the engineering requirements. During the subsequent construction and use of the building, monitoring was carried out according to the predetermined monitoring plan, and no abnormalities were found.

[0058] In summary, the method of treating the alluvial silt foundation in the lower reaches of the Yellow River by the resonance compaction method of the present invention can target the characteristics of the alluvial silt foundation in the lower reaches of the Yellow River, effectively improve the density and anti-liquefaction ability of the foundation through reasonable construction steps and parameter control, reduce the occurrence of foundation settlement and liquefaction and other problems, and has significant engineering application value.

[0059] Although 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 variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for treating alluvial silt foundation in the lower reaches of the Yellow River by resonance compaction, characterized in that: The following steps are involved: Step 1: Preliminary investigation and preparation: Conduct geological surveys on the alluvial silt foundation in the lower reaches of the Yellow River, measure the physical and mechanical parameters of the silt, calculate the natural frequency range of the foundation soil, and select appropriate resonance compaction equipment; Step 2: Site leveling and equipment positioning: Clear the surface debris, garbage and soft soil layers of the foundation site to be treated in the lower reaches of the Yellow River to make the site level; Position the resonance compaction equipment according to the predetermined spacing and arrangement, and adjust the height and levelness of the equipment so that the vibration rod is perpendicular to the foundation soil and the equipment is stable; Step 3: Resonance dense implementation: Start the resonance compaction equipment and perform resonance compaction on the foundation point by point according to the set parameters. The resonance compaction time for each construction point is 20-30 minutes. At the same time, observe the reaction of the foundation soil. If there is any abnormality, adjust the parameters in time or stop the construction process; Step 4: Quality Inspection: During the resonance compaction process, the resonance frequency of the "vibration hammer-vibration rod-foundation soil" system is monitored at all times, and the vibration parameters are adjusted in time according to the monitoring results. When the density of the foundation soil reaches the design requirements, the equipment is stopped and a comprehensive quality assessment is carried out; Step 5: Long-term monitoring of foundation settlement: After the foundation treatment is completed, the foundation settlement is monitored over a long period of time during the construction and use of the upper building, and corresponding reinforcement measures are taken based on the monitoring results.

2. The method for treating alluvial silt foundation in the lower reaches of the Yellow River by resonance compaction method according to claim 1, characterized in that: In step one, the resonant compaction equipment includes a vibrating hammer with adjustable frequency and amplitude, a counterweight system and a control system. The frequency adjustment range of the vibrating hammer covers the calculated natural frequency range, and the amplitude adjustment range of the vibrating hammer is determined according to the density requirement of the silty soil foundation.

3. The method for treating alluvial silt foundation in the lower reaches of the Yellow River by resonance compaction method according to claim 1, characterized in that: Step two also includes measuring and laying out on the leveled site according to design requirements, determining the area and construction points for resonance compaction treatment, and dividing the foundation to be treated into layers, with each layer being 0.5-1.5 meters thick.

4. The method for treating alluvial silt foundation in the lower reaches of the Yellow River by resonance compaction method according to claim 1, characterized in that: In step three, after starting the resonance compaction equipment, first penetrate the vibrating rod to the designed depth with a higher frequency and smaller amplitude, and then gradually adjust the frequency of the "vibrating hammer-vibrating rod" to resonate with the natural frequency of the foundation soil. The resonance state is judged by the vibration acceleration, and the resonance is maintained for 1-3 minutes, and then the vibrating rod is lifted to the ground; during the resonance process, the vibration frequency is adjusted in time according to the compaction of the foundation soil.

5. The method for treating alluvial silt foundation in the lower reaches of the Yellow River by resonance compaction method according to claim 1, characterized in that: In step four, the quality of the treated foundation soil is tested using in-situ testing methods and indoor geotechnical tests. Based on the test results, it is determined whether the design requirements are met, and the unqualified areas are reworked until they meet the requirements.

6. The method for treating alluvial silt foundation in the lower reaches of the Yellow River by resonance compaction method according to claim 5, characterized in that: The in-situ testing method includes a pore pressure static penetration test and a standard penetration test, and the indoor geotechnical test includes the determination of density, water content, void ratio, and shear strength indexes.

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