EQUAL ENERGY DEFORMATION COMPOSITE FOUNDATION USING MICROORGANISMS TO SOLIDIFY AGGREGATE AND THE CONSTRUCTION METHOD THEREOF

Abstract

The present invention discloses an equal energy deformation composite foundation using microorganism to solidify aggregate and a construction method thereof, the composite foundation comprises a pile body and a cushion layer, wherein the pile body is provided with several piles, the cushion layer is arranged at the top of the pile body, the pile body is connected into an integral structure through the cushion layer, and the pile body and the cushion layer are filled with aggregate solidified by microorganism. The method comprises the following steps: step 1, leveling the site; Step 2, construction preparation; Step 3, the pile driver in place; Step 4, forming a hole by hammering; Step 5, filling aggregate into the hole; Step 6, repeating the work of step 5; Step 7, forming an equal energy deformation compaction pile using microorganism to solidify aggregate; Step 8, moving to the next pile; Step 9, tamping the ground; Step 10, until the cushion is flush with the surface. Beneficial effects: using local materials, turning waste into wealth, being environmental friendly, saving project cost and conforming to the concept of green development.

Claims

1. An equal energy deformation composite foundation using a microorganism to solidify aggregate, the composite foundation comprising: a pile body and a cushion layer, wherein a plurality of piles are arranged in the pile body, the cushion layer is arranged at a top of the pile body, the pile body is connected into a whole structure by the cushion layer, and the aggregate solidified by the microorganism is filled in the pile body and the cushion layer.

2. The equal energy deformation composite foundation using microorganism to solidify aggregate according to claim 1, wherein the microorganism is Bacillus pasturii.

3. The equal energy deformation composite foundation using the microorganism to solidify aggregate according to claim 1, wherein the aggregate is a coral aggregate or a construction waste, the coral aggregate comprises a coarse aggregate and a fine aggregate, the coarse aggregate is coral gravel, and the fine aggregate is coral sand, namely calcareous sand; the construction waste comprises a concrete block, a crushed stone, a plain soil, a metal, brick, a tile and a gypsum; after treatment of screening, rolling and crushing, a particle size of construction waste is less than or equal to 30 mm.

4. A construction method for an equal energy deformation composite foundation using a microorganism to solidify an aggregate, the construction method comprising the steps of: cleaning and leveling a site; construction preparation of the site including: carrying out construction setting-out and line inspection; and checking and adjusting construction equipment; putting a pile driver in place: and centering a heavy hammer of the pile driver with a center of a pile position; forming a hole by hammering including lifting a heavy hammer at a certain height to make it fall freely and impact a foundation soil to form a hole to a controlled depth; filling the aggregate into the hole, pouring a microbial solidification liquid with a same volume as the aggregate, wherein the microbial solidification liquid is composed of a bacteria liquid and a cementing liquid, lifting the heavy hammer to a certain height, and ramming a filler repeatedly; ramming under the an action of standard ramming energy, wherein a last penetration amount of the heavy hammer is measured to a design requirement, and when a measurement is no greater than the design requirement, the filling the aggregate into the hole is repeated; repeating the step of filling the aggregate into the hole and ramming under the action of standard ramming energy, then ramming and filling the hole to the ground, and forming an energy deformation compaction pile using the microorganism to solidify the aggregate in the foundation; after one pile is formed, the construction equipment is moved to thea next pile; after a plurality of piles are formed, a ground of the site is tamped by using a plate compactor; back-filling a layer of aggregate and microbial solidification liquid with a same volume as an aggregate on the tamped ground, a back-filling elevation is higher than a ground surface by more than 0.2 m, then lifting the plate compactor to a certain height, and ramming the aggregate after microbial solidification on the ground repeatedly until the aggregate is flush with the ground surface.

5. The construction method of according to claim 4, wherein the aggregate is a coral aggregate or a construction waste, the coral aggregate comprises a coarse aggregate and a fine aggregate, the coarse aggregate is coral gravel, and the tine aggregate is coral sand; the construction waste comprises a concrete block, a crushed stone, a plain soil, a metal, brick, a tile and a gypsum; after a treatment of screening, rolling and crushing, the particle size of construction waste is less than or equal to 30 mm.

6. The construction method according to claim 4, wherein the microorganism is Bacillus pasturii and a microorganism solution is obtained by an indoor sterile culture, centrifugal concentration, low temperature transportation and an on-site expanded culture, the construction method further comprises the steps of: putting a prepared nutrient solution comprising an indoor culture, where every liter of a culture medium contains tryptone 15.0 g, Soybean peptone 5.0 g, sodium chloride 5.0 g in an autoclave, autoclaving the indoor culture at 121° C. for 20 minutes, and then cool it the indoor culture down in a sterile operation table; in order to avoid the a decomposition of urea, 20 g of a urea is added into the a bottle when a temperature drops to room temperature, and a pH is adjusted to 7.3; after microbial inoculation, the indoor culture is incubated at constantly 30° C. with oscillation for 24 hours; centrifugal concentration follows comprising: separating cultured microorganisms with a high-speed centrifuge to get the microorganisms, a temperature of a centrifugal chamber is 4° C., a rotating speed is 4000 rpm, and a duration is 15 min; after centrifugation, the a supernatant is removed, and the a precipitate is dissolved in fresh culture solution, a volume of the fresh culture solution is 1/10 of an original volume, that is, a 10 L microorganism solution is concentrated into a 1 L, and the concentrated microorganisms are filled into a plastic water bag and stored at 4° C.; low-temperature transportation ensues whereby the concentrated microorganisms are transported to the a site in an incubator, and ice bags are placed in the incubator to maintain a set low temperature in the incubator during transportation, and to ensure a rapid completion of the low temperature transportation; after the microorganisms are transported to the site, they are immediately put into a refrigerator and stored at 4° C.; on-site expanded culture follows whereby the culture medium used for expanded culture comprises: industrial soybean peptone 25 g/L, urea 10 g/L, MnSO.sub.4 12 mg/L, NiCl.6H.sub.2O 24 mg/L; the a pH value of the culture medium is adjusted to 9.0-10.0 with NaOH, and a culture time is 12 h; after the a culture is formed, a bacterial activity was tested by conductivity; the cultured microorganisms are diluted with a cementing solution which is 0.9% NaCl solution, and immediately used for on-site foundation reinforcement after dilution; a dilution ratio is 2:1; or the solution is diluted with seawater, and the dilution ratio was 3:1.

7. The construction method according to claim 4, wherein the heavy hammer has a diameter of 200 mm-600 mm, a length of 1 m-5 m and a weight of 1.5-3.5 tons, the plate compactor is a 15-ton rammer composed of steel plates, a bottom surface of the rammer is round, the a diameter of a bottom of the hammer is 2 m, and two exhaust holes with a diameter of 300 mm are arranged in the rammer.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0043] FIG. 1 is a schematic view of the overall structure of the said composite foundation according to the present invention.

[0044] FIG. 2 is a schematic view of the construction principle of the said composite foundation according to the present invention.

[0045] FIG. 3 is a process flow diagram of the said composite foundation construction method according to the present invention.

[0046] The annotations in the above figure are as follows: 1. Pile body; 2, cushion layer; 3, aggregate; 4, weight hammer; 5, microbial solidification liquid.

DETAILED DESCRIPTION OF THE INVENTION

[0047] See FIG. 1 through FIG. 3:

[0048] The equal energy deformation composite foundation using microorganism to solidify aggregate provided by the present invention comprises a pile body 1 and a cushion layer 2, wherein a plurality of pile 1 are arranged in the pile body, the cushion layer 2 is arranged at the top of the pile body 1, the pile body I is connected into a whole structure by the cushion layer 2, and a aggregate 3 solidified by microorganism is filled in the pile body 1 and the cushion layer 2.

[0049] The microorganism is Bacillus pasturii, purchased from the German Collection of Microorganisms and Cell Cultures, and the strain number is DSM33

[0050] The aggregate 3 is coral aggregate or construction waste, the coral aggregate is composed of coarse aggregate and fine aggregate, the coarse aggregate is coral gravel, and the fine aggregate is coral sand, namely calcareous sand; construction waste includes concrete block, crushed stone, plain soil, metal, brick, tile and gypsum; after treatment of screening, rolling and crushing, the particle size of construction waste is ≤30 mm.

[0051] A construction method of equal energy deformation composite foundation using microorganism to solidify aggregate provided by the present invention, the method is as follows:

[0052] Step 1, cleaning and leveling the site;

[0053] Step 2, construction preparation: carrying out construction setting-out and line inspection; checking and adjusting construction equipment;

[0054] Step 3, the pile driver in place: the center of a heavy hammer 4 is aligned with the center of the pile position;

[0055] Step 4, forming a hole by hammering: lifting the heavy hammer 4 at a certain height to make it fall freely and impact the foundation soil to form a hole to a design or controlled depth;

[0056] Step 5, filling the aggregate 3 into the hole, pouring a microbial solidification liquid 5 with the same volume as the aggregate 3, wherein the microbial solidification liquid 5 is mainly composed of bacteria liquid and cementing liquid, lifting the heavy hammer 4 at a certain height, and ramming the filler repeatedly;

[0057] Step 6, under the action of standard ramming energy, the last penetration amount of the heavy hammer 4 is measured, and when it is no greater than the design requirement, the work of step 5 is repeated;

[0058] Step 7, repeating the steps 5 and the step 6, ramming and filling the pile hole to the ground, and finally forming an energy deformation compaction pile using microorganism to solidify aggregate in the foundation;

[0059] Step 8, after one pile is formed, the equipment is moved to the next pile;

[0060] Step 9, after all piles are formed, the ground of the construction area is tamped by using a plate compactor;

[0061] Step 10, back-filling a layer of aggregate 3 and the microbial solidification liquid 5 with the same volume as the aggregate 3 on the tamped ground, the back-filling elevation is higher than the ground surface by more than 0.2 m, then lifting the plate compactor to a certain height, and ramming the aggregate cushion after microbial solidification on the ground repeatedly until the cushion is flush with the ground surface.

[0062] The aggregate 3 is coral aggregate or construction waste, the coral aggregate is composed of coarse aggregate and fine aggregate, the coarse aggregate is coral gravel, and the fine aggregate is coral sand, namely calcareous sand; construction waste includes concrete block, crushed stone, plain soil, metal, brick, tile and gypsum; after treatment of screening, rolling and crushing, the particle size of construction waste is 30 mm.

[0063] The microorganism is Bacillus pasturii, purchased from the German Collection of Microorganisms and Cell Cultures, and the strain number is DSM33; the microorganism solution is obtained by means of indoor sterile culture, centrifugal concentration, low temperature transportation and on-site expanded culture, the specific method is as follows:

[0064] Step 1, indoor cultivation: every liter of culture medium contains tryptone 15.0 g, Soybean peptone 5.0 g, sodium chloride 5.0 g, putting the prepared nutrient solution in an autoclave, autoclaving at 121° C. for 20 min, and then cool it down in a sterile operation table; in order to avoid the decomposition of urea at high temperature, 20 g urea is added into the bottle when the temperature drops to room temperature, and the pH is adjusted to 7.3; after microbial inoculation, it is incubated at constantly 30° C. with oscillation for 24 hours;

[0065] Step 2, centrifugal concentration: the cultured microorganisms arc separated by a high-speed centrifuge to get the microorganisms, the temperature of the centrifugal chamber is 4° C. , the rotating speed is 4000 rpm, and the duration is 15 min; after centrifugation, the supernatant is removed, and the precipitate is dissolved in the fresh culture solution, the volume of the fresh culture solution is 1/10 of the original volume, that is, the 10 L microorganism solution is concentrated into 1 L, and the concentrated microorganisms are filled into a plastic water bag and stored at 4° C.;

[0066] Step 3, low-temperature transportation: the concentrated microorganisms are transported to the site in an incubator, and ice bags should be placed in the incubator to maintain the set low temperature in the incubator during transportation, and to ensure the rapid completion of the whole transportation process; after the microorganisms are transported to the site, they are immediately put into a refrigerator and stored at 4° C.;

[0067] Step 4, on-site expanded culture: the culture medium used for expanded culture comprises: industrial soybean peptone 25 g/L, urea 10 g/L, MnSO.sub.4 12 mg/L, NiCl.6H.sub.2O 24 mg/L; the pH value of the culture medium was adjusted to 9.0-10.0 with NaOH, and the culture time was 12 h; after the culture, the bacterial activity was tested by conductivity method;

[0068] The cultured microorganisms were diluted with 0.9% NaCl solution which is cementing solution, and immediately used for on-site foundation reinforcement after dilution; the dilution ratio is 2:1; the solution could also be diluted with seawater nearby, and the dilution ratio was 3:1.

[0069] The heavy hammer 4 has a diameter of 200 mm-600 mm, a length of 1 m-5 m and a weight of 1.5-3.5 tons, the plate compactor is a 15-ton rammer composed of steel plates, the bottom surface of the rammer is round, the diameter of the hammer bottom is 2 m, and two exhaust holes with a diameter of 300 mm are arranged in the rammer.

[0070] The technical principle of the invention is as follows:

[0071] Firstly, the soil between piles is compacted twice. First of all, the soil between piles and the pile body are compacted by gravitational potential energy. The technical hole-forming method of the present invention features in punching and cutting the foundation soil to form a hole in way of free-falling body with the 3.5-ton heavy hammer 4, because soil is not taken in the construction process, the soil in the pile casing area is squeezed to the surrounding foundation soil, the soil body is compacted, the pores of the surrounding foundation soil are reduced, the compactness and bearing capacity of the foundation soil are improved, and the first compaction is finished; after the hole reaches the design elevation, lift the heavy hammer 4 again to tamp the filler; due to the limited constraint of the surrounding foundation soil, the diameter of the pile will be larger than that of the hole; therefore, during the pile forming process, part of the foundation soil of the pile body will be squeezed around out again, forming the second compaction of the foundation soil around the pile.

[0072] Secondly, equal energy control is used in the construction process. In the whole construction process, the same column hammer is used, lifting it in way of free falling body with the same height to tamp the filling material, and through the same one-stroke penetration extent as a control index, the measurement of the last stroke of heavy hammer 4 compaction is similar to a super-large dynamic cone penetration test, so the same one-stroke penetration extent indicates that the compactness of pile body and surrounding foundation soil is basically consistent. By controlling the filling quantity and the last blow penetration extent, the original uneven foundation becomes uniform, which will help control the uneven settlement.

[0073] Thirdly, adding a filler composed of aggregate 3 and microbial solidification liquid 5, under the ramming of the heavy hammer 4, the coarse aggregate and fine aggregate in the aggregate are fully compacted, and the microbial solidification solution 5 is fully mixed with the aggregate 3; microorganisms continuously cement the aggregate 3 and its surrounding strata in the process of metabolism, which greatly improved the strength of single pile in the later period; the high temperature generated by hammering is beneficial to the growth of microorganisms, thus beneficial to controlling uneven settlement.