Foundation treatment method for soil filling site

Abstract

According to the foundation treatment method for the soil filling site, for a building site with a deep and thick soil filling layer, the soil filling layer in the soil filling site is treated through carrier compaction piles, the treatment depth does not need to completely penetrate through the soil filling layer, and the length of the carrier compaction piles is one third to two thirds of the thickness of the soil filling layer; bottom carriers of the carrier compaction piles are mutually contacted or overlapped, and a continuous compaction reinforced soil layer with a preset thickness is formed in a foundation, so that pressure is applied to lower filling soil in a filling soil layer to complete consolidation and eliminate collapsibility, and meanwhile, additional stress generated when the pressure of a building base is transmitted to the lower filling soil is reduced; and the whole foundation soil body can meet the strength and deformation requirements of an upper structure.

Description

Technical Field

[0001] The invention relates to the field of civil engineering, and in particular to a foundation treatment method for a filling site. Background Art

[0002] The backfill in deep backfill sites has the characteristics of under-consolidation, collapsibility, poor uniformity, etc. When used as the foundation of a building, the soil strength, deformation and differential deformation cannot meet the requirements of the upper load, and reinforcement treatment is required. The reinforcement treatment methods mostly adopt construction methods such as strong tamping method and compaction pile method. The loose backfill soil is compacted by strong tamping or packing compaction, thereby improving the strength of the entire soil layer and solving the deformation problem. Whether it is the strong tamping method or the compaction method, the entire soil layer needs to be reinforced, that is, the treatment depth must exceed the thickness of the backfill soil layer. Among them, the strong tamping method is more economical, but the vibration is obvious during construction, which will cause damage to the surrounding adjacent buildings. The construction environment requirements are more picky. At the same time, due to energy limitations, its treatment depth is limited, and the treatment effect of the deeper soil cannot be guaranteed. When the traditional compaction pile method encounters a geological situation where the backfill soil layer is relatively deep, the construction is difficult and slow, which significantly increases the construction cost and construction period. In addition, the treatment effect of the deeper soil layer cannot be guaranteed, and the strength and stability are poor. Summary of the invention

[0003] In view of the above problems, the purpose of the present invention is to propose a foundation treatment method for a fill site. For a construction site with a relatively thick fill layer, the treatment depth of this method does not need to penetrate the entire fill layer. While meeting the treatment requirements, the construction difficulty and cycle are significantly reduced, thereby improving work efficiency and saving costs.

[0004] To achieve the above-mentioned purpose, the foundation treatment method of the fill site of the present invention adopts carrier compaction piles to treat the fill layer in the fill site, and the treatment depth does not need to penetrate the fill layer completely. The length of the carrier compaction piles is one-third to two-thirds of the thickness of the fill layer, and the bottom carriers of the carrier compaction piles are in contact or overlap with each other, forming a continuous compaction and reinforcement soil layer of predetermined thickness in the fill layer, thereby applying pressure to the lower fill in the fill layer to complete consolidation and eliminate wetting collapse, and at the same time reducing the additional stress when the base pressure of the building is transmitted to the lower fill, so that the entire foundation soil can meet the strength and deformation requirements of the upper structure.

[0005] Preferably, the thickness of the fill layer in the above-mentioned filling site is not less than 10m; a fill layer less than 10m is still suitable for adopting a solution that treats the entire depth.

[0006] Preferably, the shortest pile length of the above-mentioned carrier compaction pile is not less than 6m.

[0007] Preferably, the bottom of the carrier compaction pile should be below the groundwater level, that is, to ensure that the untreated part of the fill layer is below the groundwater level; for geological conditions where there is no groundwater in the entire fill layer, it is appropriate to adopt a plan to treat the entire depth to prevent the fill layer from being reduced in strength and affecting the foundation quality after being soaked by unexpected water.

[0008] Preferably, the pile spacing of the above-mentioned carrier compaction piles is not greater than the influence width of the carrier, and is set within the range of not less than 1.5m and not more than 2.5m, to ensure that the bottom carriers of each carrier compaction pile are in contact or overlap with each other, so that a continuous compacted and reinforced soil layer of predetermined thickness can be formed in the foundation. The influence width of the carrier is determined according to the soil quality, filler amount and tamping energy; the influence width of the carrier is usually in the range of 2m to 3m. The harder the soil quality and the smaller the filler amount, the smaller the influence width of the carrier; the softer the soil quality and the larger the filler amount, the larger the influence width of the carrier. However, by adjusting the tamping energy, that is, increasing the mass of the weight or increasing the drop distance of the weight, the filler amount can be artificially increased to increase the influence width and depth of the carrier.

[0009] Preferably, the predetermined thickness of the compacted and reinforced soil layer is equivalent to the influence depth of the bottom carrier of the carrier compaction pile, which is 3 to 5 m.

[0010] Preferably, the construction steps of the carrier compaction pile are: Step 1: Move the construction equipment to align with the pile position of the carrier compaction pile; Step 2: Raise the impact hammer to a predetermined height and then drop it to impact the soil to form a pile hole. Repeat the impact hole forming operation until the preset depth is reached. Step 3: Fill the pile hole with bulk filling material, lift the impact hammer to a predetermined height and then drop it, tamp the bulk filling material, and compact and reinforce the soil layer at a predetermined range and depth at the bottom of the pile hole. During this process, the amount of filling material each time should not be less than 0.1m 3 , the number of tamping after each filling is not less than 2 times; Step 4: After multiple filling tamping operations, measure the penetration of the impact hammer to detect the compaction degree of the pile end carrier. The penetration standard is: measure the penetration after a single hammer tamping, requiring the single penetration settlement value to be no more than 5cm; or measure the total penetration after three consecutive hammer tampings, requiring the total penetration settlement value to be no more than 15cm, so as to form a carrier with an impact width of 2~3m and an impact depth of 3~5m at the pile end; Step 5: Continue to fill the pile hole with bulk filling material to a height of 1m to 2m, lift the weight to a predetermined height and then let it fall freely, tamp the filled bulk filling material, and through continuous filling tamping operation, the soil layer in a predetermined range and height around the pile hole is compacted and reinforced, and then the compaction degree is controlled by a penetration standard equal to or lower than step 4; Step 6: Repeat the operation of step 5, continuously raise the filler tamping height in the pile hole, and use the same penetration standard as step 5 to control the degree of compaction. When it rises to or close to the foundation surface, the construction of the compaction pile is completed, and it is ensured that the density of the pile body material and the soil around the pile is uniform from bottom to top.

[0011] Generally speaking, the control standard for the compaction degree of the pile end carrier in the above step 4 is relatively high. First, the carrier needs to bear more of the bearing capacity, and second, it needs to ensure that the carriers of adjacent piles are in contact or overlap with each other. The control standard for the compaction degree of the pile body in steps 5 and 6 can be relatively moderately lowered.

[0012] It is best to compact the surface of the entire site by strong tamping or rolling after all the carrier compaction piles are constructed in the entire fill site.

[0013] Preferably, the bulk filler used in the construction of carrier compaction piles is one or more of the following materials: construction waste, slag, coal gangue, miscellaneous soil, crushed stone, and sand and gravel.

[0014] It is best to carry out settlement observations before, during and after the construction of foundation treatment; this includes layered consolidation settlement observations within the depth range of the site fill before construction, with an observation point set every 2m within the depth range and no less than 3 points set for observation every 1000㎡ on the plane. During construction, settlement observations can be continued at the settlement observation points set before construction. After construction, settlement observations should be carried out on the building. The stability standard of settlement shall be implemented in accordance with the "Code for Measurement of Building Deformation".

[0015] The characteristics and advantages of the foundation treatment method for the fill site of the present application are: ① Through the mutual influence and overlap of the bottom carriers of the carrier compaction pile, a compaction and strengthening soil layer with a certain thickness is formed in the deep fill layer, thereby exerting pressure on the lower fill to complete consolidation and eliminate collapse; ② The compaction and strengthening soil layer forms an integral structural layer, reducing the additional stress when the building base pressure is transmitted to the lower fill, thereby reducing the strength requirements of the foundation soil below the compaction structural layer formed by the carrier; ③ In the construction of the carrier compaction pile, the same standard is adopted to control the compaction degree in the graded filling process of the pile body. When the soil layer at a certain part of the pile body is soft, the filling amount must be increased to achieve the same The penetration rate is the same as that of pile body materials, and when the soil layer is harder, the amount of filler will naturally decrease to achieve the same penetration rate, thereby ensuring that when the hardness of the soil around the pile body changes, the density of the pile body material and the soil around the pile can be uniform. This is true not only for each individual pile, but also for the entire building foundation. When the penetration rate of each pile is controlled the same, the bearing capacity of the entire foundation can be guaranteed to be uniform, thereby significantly reducing the uneven settlement of the foundation; ④ The treatment depth does not need to penetrate the fill layer completely, and the construction difficulty and cycle are significantly reduced. Therefore, while the work efficiency is improved, the cost can be significantly saved; ⑤ The construction process has strong continuity and high work efficiency, can absorb a large amount of engineering waste, and is environmentally friendly and pollution-free. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of an embodiment of a method for treating a foundation of a fill site according to the present invention. DETAILED DESCRIPTION

[0017] Figure 1 FIG. 1 is a schematic diagram of an embodiment of a method for treating a foundation of a landfill site according to the present invention. Figure 1 As shown, there is a deep and recent fill layer 1 in the construction site of this embodiment, the soil layer thickness is 20m, the soil layer property is miscellaneous fill, the groundwater level is 10m, and the carrier compaction pile 2 is used to treat the deep fill layer. The design principle of the treatment scheme is: the pile length of the carrier compaction pile 2 is within the range of one-third to two-thirds of the thickness of the fill layer 1, and the pile spacing of the carrier compaction pile 2 is not greater than the influence width of the bottom carrier 3. According to geological conditions and field tests, the specific scheme is determined as follows: the pile length of the carrier compaction pile is set to 11m, the influence width of the bottom carrier of the carrier compaction pile is 2m, and the influence depth is 3.5m. Therefore, the pile spacing of the carrier compaction pile is set to 1.8m, ensuring that the bottom carriers 3 of the carrier compaction pile 2 overlap with each other, and can form a continuous compaction and strengthening soil layer with a thickness of 3.5m in the foundation, thereby exerting pressure on the lower fill in the deep fill layer to complete the wetting and consolidation, and at the same time reducing the additional stress when the building base pressure is transmitted to the lower fill, so that the entire foundation soil can meet the strength and deformation requirements of the upper structure.

[0018] During the construction of the single carrier compaction pile of the present embodiment, the compaction degree of the pile end carrier and the pile body is controlled by the penetration degree of the heavy hammer tamping, wherein the penetration control standard of the pile end carrier is that the single penetration settlement value is not more than 5 cm, and the penetration control standard of the pile body is that the single penetration settlement value is not more than 8 cm, to ensure that the density of the pile body material and the soil around the pile from bottom to top is uniform; during the construction of all the carrier compaction piles in the entire site, the compaction degree of the pile end carrier and the pile body is controlled according to the same penetration standard.

Claims

1. A method for treating a foundation of a fill site, characterized in that: Carrier compaction piles are used to treat the fill layer in the fill site, and the treatment depth does not need to penetrate the fill layer completely. The length of the carrier compaction piles is one-third to two-thirds of the thickness of the fill layer, and the bottom carriers of the carrier compaction piles are in contact or overlap with each other, forming a continuous compacted and reinforced soil layer of predetermined thickness in the fill layer, thereby applying pressure to the lower fill in the fill layer to complete consolidation and eliminate wetting, while reducing the additional stress when the base pressure of the building is transmitted to the lower fill, so that the entire foundation soil can meet the strength and deformation requirements of the upper structure.

2. The method for treating the foundation of a landfill site according to claim 1, characterized in that: The thickness of the fill layer in the above-mentioned filling site shall not be less than 10m.

3. The method for treating the foundation of a fill site according to claim 1 or 2, characterized in that: The shortest pile length of the above-mentioned carrier compaction piles shall not be less than 6m.

4. The method for treating the foundation of a fill site according to any one of claims 1 to 3, characterized in that: The bottom end of the above-mentioned carrier compaction pile should be below the groundwater level.

5. The method for treating the foundation of a fill site according to any one of claims 1 to 4, characterized in that: The pile spacing of the above-mentioned carrier compaction piles is not greater than the influence width of the carrier, and is set within the range of not less than 1.5m and not more than 2.5m, ensuring that the bottom carriers of each carrier compaction pile are in contact or overlap with each other, thereby being able to form a continuous compacted and reinforced soil layer of predetermined thickness in the foundation. The influence width of the carrier is determined based on the soil quality, filler amount, and tamping energy.

6. The method for treating the foundation of a fill site according to any one of claims 1 to 5, characterized in that: The predetermined thickness of the compacted and reinforced soil layer is equivalent to the influence depth of the bottom carrier of the carrier compaction pile, which is 3 to 5 m.

7. The method for treating the foundation of a fill site according to any one of claims 1 to 6, characterized in that: The construction steps of the above-mentioned carrier compaction pile are: Step 1: Move the construction equipment to align with the pile position of the carrier compaction pile; Step 2: Raise the impact hammer to a predetermined height and then drop it to impact the soil to form a pile hole. Repeat the impact hole forming operation until the preset depth is reached. Step 3: Fill the pile hole with bulk filling material, lift the impact hammer to a predetermined height and then drop it, tamp the bulk filling material, and compact and reinforce the soil layer at a predetermined range and depth at the bottom of the pile hole. During this process, the amount of filling material each time should not be less than 0.1m 3 , the number of tamping after each filling is not less than 2 times; Step 4: After multiple filling tamping operations, measure the penetration of the impact hammer to detect the compaction degree of the pile end carrier. The penetration standard is: measure the penetration after a single hammer tamping, requiring the single penetration settlement value to be no more than 5cm; or measure the total penetration after three consecutive hammer tampings, requiring the total penetration settlement value to be no more than 15cm, so as to form a carrier with an impact width of 2~3m and an impact depth of 3~5m at the pile end; Step 5: Continue to fill the pile hole with bulk filling material to a height of 1m to 2m, lift the weight to a predetermined height and then let it fall freely, tamp the filled bulk filling material, and through continuous filling tamping operation, the soil layer in a predetermined range and height around the pile hole is compacted and reinforced, and then the compaction degree is controlled by a penetration standard equal to or lower than step 4; Step 6: Repeat the operation of step 5, continuously raise the filler tamping height in the pile hole, and use the same penetration standard as step 5 to control the degree of compaction. When it rises to or close to the foundation surface, the construction of the compaction pile is completed, and it is ensured that the density of the pile body material and the soil around the pile is uniform from bottom to top.

8. The method for treating the foundation of a fill site according to any one of claims 1 to 7, characterized in that: After the construction of all carrier compaction piles in the entire fill site is completed, the surface of the entire site is compacted and compacted by strong tamping or rolling.

9. The method for treating the foundation of a fill site according to any one of claims 1 to 8, characterized in that: The bulk filling material used in the construction of carrier compaction piles is one or more of the following materials: construction waste, slag, coal gangue, miscellaneous soil, crushed stone, sand and gravel, and cement mixture.

10. The method for treating the foundation of a fill site according to any one of claims 1 to 9, characterized in that: Settlement observations are carried out before, during and after the construction of foundation treatment.

Images