Soft material in-situ compaction and consolidation method

Abstract

The invention provides a soft material in-situ compaction and consolidation method, which belongs to the technical field of soft material in-situ consolidation, and comprises the following steps: site preparation and material backfilling exceeding the standard height; construction equipment enters the field, firstly, the surface layer of the soft material is slightly tamped through a 150 kN phi 2500 heavy hammer, and full tamping is conducted along the straight line circle-circle tangency; when the pore water pressure dissipation expires, the 150 kN phi 1000 rammer is used for improving the first-level potential energy to conduct re-ramming from the starting point; the steps 2-3 are repeated, and the surface layers of the materials are tamped in a line-changing circulating and reciprocating mode in sequence; and when the number of times of tamping energy is larger than or equal to 12 levels, final tamping energy is confirmed, and the hammer is collected. According to the method, firstly, the surface layer of the soft material is tamped through low-energy tamping energy, and under the action of low-energy impact waves, pore water pressure and gas are slowly released and surged towards the far end in the radial direction of cracks and capillary channels in the material. And when the liquid phase and the gas phase are squeezed less, the tamping energy is larger and larger, and the materials are squeezed more and more densely. And when the consolidation requirement is high, high-energy ramming energy is selected for final ramming. When the heavy hammer jumps and the vibration sense of the surface of the material is strong, the solidification effect is particularly remarkable.

Description

Technical Field

[0001] The invention belongs to the technical field of in-situ consolidation of soft materials, and in particular relates to an in-situ compaction consolidation method for soft materials. Background Art

[0002] Generally, under-consolidated soft materials with high water content are relatively thick and huge in volume, making solid-liquid separation difficult. Conventional technologies have many problems, such as complicated procedures, long cycles, many consumables, high costs, large amounts of ex situ consolidation engineering, and poor environmental protection. In the existing technology, vacuum preloading relies on passive pumping and piled preloading pumping. The disadvantage is that the construction period is long and it is necessary to insert drainage boards, vacuumize, and pile counterweights. Conventional dynamic compaction technology encounters high-water-content under-consolidated soft materials. When the original structure is disturbed and destroyed, and the surrounding pore water penetration is blocked, rubber soil or local uplift is likely to occur, and it cannot be compacted. The pain points of the existing technology are poor post-construction consolidation effect, insufficient impact depth, and difficult to control deformation. Especially in the treatment of soft foundations, conventional technologies are only aimed at meeting the requirements of the upper equipment, and the force-bearing properties of the soft materials have not changed substantially. In the future, pile foundations still need to be compensated in order to meet the load transfer function of the upper structure. Summary of the invention

[0003] In view of this, the object of the present invention is to provide an in-situ compaction consolidation method for soft materials. The method provided by the present invention first uses low-energy tamping energy to gently tamping the surface of the soft material, and under the action of the low-energy shock wave, causes the pore water pressure and gas to slowly release and surge along the cracks and capillary channels in the material radially toward the distal end. As the pore water and gas become less and less, the tamping energy becomes greater and greater, and the material becomes denser and denser. When the material is basically compacted, high-energy tamping energy is used for the final tamping. When the penetration of the last three hits is less than that of the previous hit, the heavy hammer produces a jumping phenomenon, and the surface of the material vibrates strongly, the consolidation effect is particularly significant.

[0004] By using the method provided by the present invention, soft materials are effectively reinforced after in-situ drainage and consolidation. Especially when a large amount of soft materials are consolidated in situ, the soft materials are separated into solid and liquid, and the volume is compressed, which is convenient for transportation; after the soft base is consolidated in situ, the bearing capacity per unit area and the compression modulus are effectively improved.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides an in-situ compaction consolidation method for soft materials, comprising the following steps:

[0007] 1) Site preparation and backfilling of materials exceeding the standard height;

[0008] 2) When the construction equipment enters the site, first use a 150kNΦ2500 heavy hammer to lightly tamp the surface of the soft material, and then tamp it fully along the straight line and circle;

[0009] 3) When the pore water pressure dissipation period expires, use a 150kNΦ1000 tamping hammer to increase the first level of potential energy and tamp again from the starting point;

[0010] 4) Repeat steps 2) to 3), changing the rows in turn to tamp the surface of the material in a reciprocating cycle;

[0011] 5) When the number of tamping times is ≥12, the penetration of the last three strikes is less than that of the previous strike, and the vibration on the surface of the material is strong, confirm the final tamping energy and stop hammering.

[0012] Preferably, the soft materials include highly water-containing industrial waste, riverbed mud, municipal waste soil, beach fill sludge and soft soil.

[0013] Preferably, the excessively high backfill materials include the comprehensive resource utilization of abandoned soil, slag, construction waste and industrial waste.

[0014] Preferably, the pore water pressure dissipation period is not less than 10 days.

[0015] Preferably, the potential energy ranges from 100 to 3000 kN.m, and the number of times is at least 12 levels, and the potential energy is increased step by step to tamp the surface of the material.

[0016] Preferably, the last three penetrations are performed in the final passes. If the requirements are not met, the tamping operations are repeated repeatedly until the design requirements are met.

[0017] Preferably, the final tamping energy is set based on material consolidation requirements, geological conditions and foundation bearing capacity design requirements.

[0018] Preferably, when the characteristic value of the foundation bearing capacity is not greater than 500 kPa and the compression modulus is not greater than 40 MPa, the lifting height of the heavy hammer is not higher than 20 m, and the ramming energy is not greater than 3000 kN.m.

[0019] Preferably, when the characteristic value of the foundation bearing capacity is greater than 500 kPa and the compression modulus is greater than 40 MPa, the lifting height of the heavy hammer is not higher than 30 m, and the final tamping energy can be set to 10,000 to 30,000 kN.m.

[0020] The present invention also provides the above-mentioned soft material in-situ compaction consolidation method, which is suitable for application in various soft material in-situ consolidation or ex-situ consolidation projects.

[0021] The advantages of the present invention over the prior art are:

[0022] 1) No drainage: The whole process of the present invention relies on the vertical step-by-step increase in kinetic energy to slowly compact the material from low to high and from shallow to deep. It is a pure physical method of active compaction, and the phase change is basically completed during the construction. Especially in the field of geotechnical engineering, the existing technology focuses on passive drainage, through equipment pumping or pressurizing water, which is difficult, requires more consumables, has a long construction period, has more processes, and is expensive. The pain points are the poor treatment depth and consolidation effect. The present invention utilizes dynamic consolidation, and the material is slowly compacted. By gradually increasing the potential energy to tamp the surface of the material, the purpose of in-situ compaction and consolidation of soft materials is achieved.

[0023] 2) No high-energy-consuming materials: The present invention adopts a purely physical compaction method. No materials are used in the whole process. The consolidation effect of the materials after the process is ideal. The relevant parameters are much higher than the existing national standards and existing technologies. It can avoid the use of high-energy-consuming materials such as mountain opening and filling, vacuum preloading and drainage boards, preloading, pile foundation engineering, and foundation pit support, which is in line with the national industrial policies and the environmental protection requirements of "zero-carbon buildings".

[0024] 3) Impact depth: The present invention uses a dynamic consolidation method. As the construction period increases, under the influence of the gradually increasing shock waves, the under-consolidated materials become more and more dense, and the impact depth becomes deeper and deeper. The impact depth is closely related to geological conditions and is proportional to the construction period and impact energy.

[0025] 4) Backfilling at excessive height: During the operation of the present invention, the soft material has a very large settlement amount, resulting in a huge volume loss. According to the estimation, backfilling at excessive height should be done in advance to compensate for the volume loss caused by the large material settlement amount and insufficient elevation of the original site. The surface layer of the backfill should preferably use abandoned soil and slag with better particle grading, focusing on assisting the government in solving the problem of large-volume high-water-content solid waste and abandoned soil disposal, and realizing the effective comprehensive utilization of solid waste resources.

[0026] 5) Problem solving: The existing technology generally believes that the greater the impact energy, the better. When the soft material has a low permeability coefficient and is rich in pore water, under the action of the high-energy impact energy shock wave, the liquid and gas phases in the material can only be released instantly toward the weakest surface, forming rubber soil or local uplift. The soft material basically loses its consolidation function, and this problem can never be solved.

[0027] The technical solution of the present invention is to compact the material gradually by starting with light work and then working from shallow to deep, in turns. Through the cycle rotation interval period, the compacted material is left with sufficient pore water pressure dissipation period and material consolidation period, effectively avoiding the defects of the existing technology.

[0028] 6) Shortened construction period: The existing technology has complicated processes. The more links there are between the processes, the more mutually restrictive factors there are, and the more difficult it is to coordinate. The whole process of the present invention is completed in one go, especially for soft foundation treatment projects. Under the condition of site landing, if the estimated settlement exceeds the standard height for backfilling, the equipment can be brought into the site in advance, or backfilling and working at the same time, and implemented simultaneously with environmental assessment and other procedures. When the construction period is advanced, it is conducive to shortening the construction period, which is equivalent to putting the project into operation in advance, and the social and economic benefits are more significant. Conventional technology cannot do this. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a process flow chart of in-situ compaction and consolidation of soft materials according to the present invention. DETAILED DESCRIPTION

[0030] The present invention provides an in-situ compaction consolidation method for soft materials, comprising the following steps:

[0031] 1) Site preparation and backfilling of materials exceeding the standard height;

[0032] 2) Construction equipment enters the site, first use a 150kNΦ2500 heavy hammer to lightly tamp the surface of the soft material, and then fully tamp along the straight line and circle;

[0033] 3) When the pore water pressure dissipation period expires, use a 150kNΦ1000 tamping hammer to increase the first level of potential energy and tamp again from the starting point;

[0034] 4) Repeat steps 2) to 3), changing the rows in turn to tamp the surface of the material in a reciprocating cycle;

[0035] 5) When the number of impact energy is ≥12, the penetration of the last three impacts is less than the previous one, and the vibration on the surface of the material is strong, confirm the final impact energy and stop hammering.

[0036] The soft material is not particularly limited in the present invention, and preferably includes high-water-content industrial waste, riverbed mud, municipal waste soil, beach fill sludge and soft soil.

[0037] In the present invention, for underground pore water, it is preferred to start the operation at the shallowest point based on the groundwater level provided by relevant data, and then follow the groundwater flow to the downstream and the far end.

[0038] In the present invention, when the step-by-step energy enhancement is preferably constructed, the tamping energy ranges from 100 to 3000 kN.m, and the number of times is ≥12 levels, and the potential energy or kinetic energy is gradually increased to tamping the surface of the material.

[0039] In the present invention, the heavy hammer light tamping preferably uses a heavy hammer with a smaller diameter to tamp the surface of the material from light to heavy, with a larger unit pressure.

[0040] In the present invention, the construction equipment is preferably domestic low-energy compaction equipment, which uses pure physical methods to complete the in-situ phase change of soft materials.

[0041] In the present invention, the construction process preferably includes: site preparation → backfilling of materials exceeding the standard → equipment entering the site → trial tamping at the starting point of the site → first use a 150kNΦ2500 heavy hammer to lightly tamp the surface of the material → fully tamp along the straight line and circle → set a dissipation period of 10 to 15 days / level for the pore water pressure in the material → then change to a 150kNΦ1000 tamping hammer to increase the potential energy by one level and tamp again from the starting point → tamp the surface of the material in turn → alternately tamp with circles tangent to each other → alternately set a dissipation period → reciprocate → tamping energy from light to heavy → when the tamping energy number is ≥12 levels and reaches the limit, the hammer withdrawal standard is: the final three penetration degrees, each blow is less than the previous blow, based on the three indicators of the rebound height of the heavy hammer and the vibration on the surface of the material → the equipment is withdrawn.

[0042] For projects with higher foundation bearing capacity and compression modulus requirements, such as iron ore yard projects, using the method provided by the present invention, under the condition that the pore water has been largely squeezed out, if a high-energy heavy hammer is used to tamp the material surface with high potential energy, the material will not produce rubber soil or local uplift, and the post-construction effect is very significant.

[0043] When there are ponds and swamps in the site, the present invention does not require drainage or silt removal and can directly cover the material. Later, under vertical kinetic energy operation, the soft material can complete in-situ drainage and consolidation with a good effect.

[0044] The method provided by the present invention can flexibly adjust different equipment and construction periods according to different project parameter requirements, adapt to the project and meet national standards and design requirements. For example, in a terminal project, stacking containers and stacking iron ore, the construction parameters and processing depth requirements can be different according to different geological conditions, and the corresponding equipment and construction period can be flexibly adjusted. Using the method of the present invention, under the premise of meeting the construction period, not only can the relevant construction parameters be greatly improved, the investment can be reduced by 60-80%, and the construction period can be shortened, but also, under the condition that the site remains unchanged, the storage capacity can be increased by 3-8 times, and the later maintenance is basically zero.

[0045] For petrochemical tank farm projects, the post-construction effect of the present invention can not only avoid pile foundation engineering, but also avoid reinforced concrete caps, and reduce the deadweight of the structure. It only requires the construction of ring beams and the laying of cushion layers.

[0046] For large-span storage buildings, by utilizing the method provided by the present invention, the floor can not only avoid pile foundation engineering, but also avoid beam-slab structure, thereby increasing storage capacity.

[0047] For expressways and municipal engineering projects, the method provided by the present invention can be used to directly pave the concrete pavement without the need for a base layer and a water-stabilizing layer.

[0048] For the site deficit project, the method provided by the present invention is used to fill the high-cover materials that exceed the estimated post-construction settlement, and the process is completed in one go to meet the load transfer requirements of the upper buildings without repeated rolling and secondary treatment.

[0049] For offshore island and bridge construction and energy island construction projects, the sea silt can be blown away nearby, and the solid-liquid separation can be performed in situ, and the technology of the present invention can be used to achieve the purpose of soil consolidation, and the construction materials can be transported over long distances.

[0050] For sites with water-stopping requirements, the present invention preferably tamps the under-consolidated soft material along the red line to form a water-stopping sealing wall with a width of 10 to 30 meters.

[0051] For under-consolidated materials such as high-water-content industrial solid waste, municipal sludge, and riverbed mud, the present invention can dispose of them in situ or ex situ, completely avoiding large-volume dumping and facilitating transportation.

[0052] The technical solution provided by the present invention is described in detail below in conjunction with the embodiments, but the following embodiments cannot be understood as limiting the protection scope of the present invention.

[0053] Example 1

[0054] The site is first prepared, and water is not drained when there is water in the site, and silt is not dug. According to the estimated total settlement, the excess material is backfilled; after the equipment enters the site, first test tamping, lift a 150kNΦ2500 heavy hammer to lightly tamp, and the surface of the material is lightly tamped in a straight line along the starting point at a tangent of 400~600; when the pore water pressure dissipates, use a 150kNΦ1000 tamping hammer to tamp again in a straight line along the starting point at a tangent of 300~400; when the pore water pressure dissipates, start another row at a tangent of 400~600 in an alternating manner, and repeat the previous process of full tamping alternately. By analogy, the operation is repeated in turns, increasing the tamping energy from light to heavy, and continuously compacting the material from shallow to deep, step by step, until the full tamping operation of the entire site is completed.

[0055] Example 2

[0056] Use domestic dynamic compaction equipment, first use a Φ2500 150kN heavy hammer, hoisting height 300 ~ 600, according to ≤100kN.m first full compaction once, change the row and move forward alternately; then use a Φ1000 150kN heavy hammer, increase the energy by one level, and fully compact along the original line once, and then change the row and move forward alternately; the whole field is rotated once, then return to the starting point, increase the energy by one level, and follow the above process to fully compact the whole field again, and so on. Leave enough time for the pore water pressure to dissipate between each pass ≥10 ~ 15 days. When the number of full compaction passes in the whole field is ≥12 levels, it is necessary to pay attention to the penetration of the last three blows, each blow is less than the previous blow, the rebound height of the heavy hammer and the ground vibration, and then decide the final compaction and hammering standard.

[0057] For soft foundation treatment projects, when the characteristic value of foundation bearing capacity is ≤300-500kPa and the compression modulus is ≤30-40MPa, the weight lifting height is ≤20m and the tamping energy is ≤3000kN.m, which can meet national standards and design requirements. When the characteristic value of foundation bearing capacity is >500kPa and the compression modulus is >40MPa, the final tamping energy can be 10000-30000kN.m. See Appendix 1-3 for a comparison of technical effects.

[0058] Economic comparison of solutions

[0059] Appendix 1

[0060]

[0061] Post-process parameter comparison

[0062] Appendix 2

[0063]

[0064] Step-by-step energy enhancement parameter table

[0065] Appendix 3

[0066]

[0067] Note:

[0068] A: The characteristic value of foundation bearing capacity is ≤300~500kPa, and the compression modulus is ≤30~40MPa;

[0069] B: The characteristic value of foundation bearing capacity is greater than 500kPa, and the compression modulus is greater than 40MPa, which is suitable for projects with higher requirements.

[0070] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for in-situ compaction and consolidation of soft materials, characterized in that: The following steps are involved: 1) Site preparation and backfilling of materials exceeding the standard height; 2) Construction equipment enters the site, first use a 150kNΦ2500 heavy hammer to lightly tamp the surface of the soft material, and then fully tamp along the straight line and circle; 3) When the pore water pressure dissipation period expires, use a 150kNΦ1000 tamping hammer to increase the first level of potential energy and tamp again from the starting point; 4) Repeat steps 2) to 3), changing the rows in turn to tamp the surface of the material in a reciprocating cycle; 5) When the number of tamping times is ≥12, the penetration of the last three strikes is less than that of the previous strike, and the vibration on the surface of the material is strong, confirm the final tamping energy and stop hammering.

2. The in-situ compaction consolidation method for soft materials according to claim 1, characterized in that: In the step 1), the soft materials include industrial waste with high water content, riverbed mud, municipal waste soil, beach fill sludge and soft soil.

3. The in-situ compaction consolidation method for soft materials according to claim 1, characterized in that: In the step 1), the excessive backfill materials include waste soil, slag, construction waste and industrial waste for comprehensive resource utilization.

4. The in-situ compaction consolidation method for soft materials according to claim 1, characterized in that: In the step 3), the pore water pressure dissipation period is not less than 10 days.

5. The in-situ compaction consolidation method for soft materials according to claim 1, characterized in that: In the step 4), the potential energy ranges from 100 to 3000 kN.m, and the number of times is at least 12 levels, and the potential energy is increased step by step to tamp the surface of the material.

6. The in-situ compaction consolidation method for soft materials according to claim 1, characterized in that: In step 5), the last three penetrations are performed in the final number of passes. If the requirements are not met, the tamping operation is repeated repeatedly until the design requirements are met.

7. The in-situ compaction consolidation method for soft materials according to claim 1, characterized in that: In the step 5), the final tamping energy is set based on the consolidation requirements of different materials, geological conditions and foundation bearing capacity design requirements.

8. The in-situ compaction consolidation method for soft materials according to claim 7, characterized in that: When the characteristic value of the foundation bearing capacity is not greater than 500kPa and the compression modulus is not greater than 40MPa, the lifting height of the heavy hammer is not higher than 20m, and the ramming energy is not greater than 3000kN.m.

9. The in-situ compaction consolidation method for soft materials according to claim 7, characterized in that: When the characteristic value of the foundation bearing capacity is greater than 500 kPa and the compression modulus is greater than 40 MPa, the lifting height of the heavy hammer is not higher than 30 m, and the final tamping energy can be set to 10,000 to 30,000 kN.m.

10. Application of the in-situ compaction consolidation method for soft materials as claimed in claim 1 in various in-situ consolidation or ex-situ consolidation projects for soft materials.

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