CN118345782A - Safe stress release hole construction method capable of eliminating soil compaction effect - Google Patents
Safe stress release hole construction method capable of eliminating soil compaction effect Download PDFInfo
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- CN118345782A CN118345782A CN202410354415.2A CN202410354415A CN118345782A CN 118345782 A CN118345782 A CN 118345782A CN 202410354415 A CN202410354415 A CN 202410354415A CN 118345782 A CN118345782 A CN 118345782A
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- 239000002689 soil Substances 0.000 title claims abstract description 75
- 238000010276 construction Methods 0.000 title claims abstract description 34
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- 238000005056 compaction Methods 0.000 title claims description 8
- 239000004576 sand Substances 0.000 claims abstract description 67
- 238000005553 drilling Methods 0.000 claims abstract description 41
- 230000008014 freezing Effects 0.000 claims abstract description 40
- 238000007710 freezing Methods 0.000 claims abstract description 40
- 238000002955 isolation Methods 0.000 claims abstract description 32
- 238000000034 method Methods 0.000 claims abstract description 13
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- 230000008030 elimination Effects 0.000 claims abstract description 6
- 238000003379 elimination reaction Methods 0.000 claims abstract description 6
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- 229910000831 Steel Inorganic materials 0.000 claims description 49
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- 238000012360 testing method Methods 0.000 claims description 25
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- 239000004570 mortar (masonry) Substances 0.000 claims description 18
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 12
- 239000004568 cement Substances 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 238000005520 cutting process Methods 0.000 claims description 8
- 238000011049 filling Methods 0.000 claims description 8
- -1 polydimethylsiloxane Polymers 0.000 claims description 7
- 229920002134 Carboxymethyl cellulose Polymers 0.000 claims description 6
- 229910052791 calcium Inorganic materials 0.000 claims description 6
- 239000011575 calcium Substances 0.000 claims description 6
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 6
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 6
- 235000010948 carboxy methyl cellulose Nutrition 0.000 claims description 6
- 239000008112 carboxymethyl-cellulose Substances 0.000 claims description 6
- 239000004205 dimethyl polysiloxane Substances 0.000 claims description 6
- 229920001903 high density polyethylene Polymers 0.000 claims description 6
- 239000004700 high-density polyethylene Substances 0.000 claims description 6
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 6
- 229910052902 vermiculite Inorganic materials 0.000 claims description 6
- 235000019354 vermiculite Nutrition 0.000 claims description 6
- 239000010455 vermiculite Substances 0.000 claims description 6
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 5
- 238000004140 cleaning Methods 0.000 claims description 5
- 238000009533 lab test Methods 0.000 claims description 5
- 239000002994 raw material Substances 0.000 claims description 5
- 239000002023 wood Substances 0.000 claims description 5
- 238000003825 pressing Methods 0.000 claims description 4
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Landscapes
- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
Abstract
The invention provides a construction method of a safe stress release hole with a soil squeezing effect elimination function, and belongs to the technical field of stress release holes. The method comprises the following steps: s1, evaluating geological conditions; s2, prepressing the isolation trench; s3, drilling a stress release hole; s4, reinforcing the stress release holes; according to the stress release hole construction method, the geological conditions are evaluated, the engineering characteristics of soil are fully known, scientific basis is provided for the layout of the stress release holes, isolation trenches are excavated at the periphery of a layout area before the stress release holes are selected, meanwhile, the isolation trenches are treated by adopting a combination of vacuum pumping and freezing treatment, the stress release holes are drilled in different areas, and sand pile rings are arranged at the periphery of each stress release hole, so that the transmission of earth surface vibration waves caused by drilling can be effectively reduced and blocked, earth surface humping is reduced, and the earth squeezing effect generated during the construction of the stress release holes is fully eliminated.
Description
Technical Field
The invention belongs to the technical field of stress release holes, and particularly relates to a safe type stress release hole construction method capable of eliminating soil squeezing effect.
Background
At present, the precast tubular pile and the square pile are widely applied because of reliable construction quality and high speed, but because the precast tubular pile and the square pile are used, soil squeezing effect often occurs, so that the surrounding adjacent buildings, pipelines and roads are damaged to different degrees, and the damage range of the influence is mainly concentrated in a pile-sinking area of 10-20 meters according to relevant data and actual engineering observation. Buildings within this range are extremely prone to uneven settlement, cracking and even failure. And adverse effects are brought to construction and property parties.
The stress relief hole is a hole preset in the engineering structure, and is mainly used for relieving residual stress generated in the material processing, assembly or other manufacturing processes, wherein the residual stress refers to self-balanced internal stress state existing in the component without external force, and the stress can adversely affect the performance and service life of the structure, so that the stress is required to be relieved or controlled by a proper method.
In engineering practice, effective measures for avoiding adverse effects of soil compaction effect on the surrounding environment are widely applied, and the stress relief hole rule is an effective measure. The principle is that by arranging reasonable stress release holes, pore water pressure generated in the pile pressing process is dissipated into the stress release holes, and the extrusion effect of a body is relieved, so that the influence of soil deformation on the surrounding environment is greatly reduced, and therefore, a safe type stress release hole construction method with the soil extrusion effect elimination is needed.
Disclosure of Invention
Aiming at the problems, the invention provides a safe type stress release hole construction method capable of eliminating the soil squeezing effect.
The technical scheme of the invention is as follows: a construction method of a safe stress release hole with the effect of eliminating soil compaction comprises the following steps:
S1, evaluating geological conditions:
Drilling and obtaining a soil sample in a preset area, performing laboratory test, determining possible high ground stress and high elastic energy concentration areas in a construction area according to the obtained test result, and determining the number, the aperture and the layout area of stress release holes;
S2, pre-pressing treatment of an isolation trench:
Cleaning sundries on the ground of a layout area, flattening the ground, excavating an isolation trench at the periphery of the layout area, paving a sand cushion layer with the thickness of 34-40cm in the isolation trench, paving a layer of sealing film at the upper end of the sand cushion layer, pumping air under the sealing film to form a vacuum state by using a vacuum pump, accelerating the water in the soil to push to a drainage facility and discharge the water due to the pressure difference between the inside and the outside of the sealing film, drilling a plurality of freezing holes at two sides of the isolation trench, pumping freezing pipes into each freezing hole, and freezing soil layers at two sides of the isolation trench by utilizing freezing equipment until the frozen soil layers reach the designed freezing thickness and the freezing strength;
s3, drilling a stress release hole:
Cutting a preset area into a plurality of subareas, measuring and paying off in each subarea according to a construction drawing, determining drilling points of each stress release hole, erecting a drilling machine at the drilling points, enabling the center of the drilling machine and the center of the drilling points to be on the same plumb line, then drilling the stress release holes by using the drilling machine, controlling drilling depth according to platform elevation of the drilling machine, and repeating the steps until a sufficient number of stress release holes are drilled;
S4, reinforcing the stress release holes:
And installing grouting pipes in the drilled stress release holes, tightly sealing the periphery of the grouting pipes, injecting micro-expansion slurry into the grouting pipes at the rate of 50-60mL/s, wherein the grouting pressure is 0.8-0.9Mpa, cutting off the exposed grouting pipes, trowelling with cement slurry, and closing the grouting holes.
Further, in step S1, when laboratory testing is performed on the obtained soil sample, the elastic modulus, cohesive force, poisson ratio of the soil sample are measured, and the test results are shown as follows:
If the elastic modulus is less than or equal to 5.4MPa, the cohesive force is less than or equal to 15KPa, the Poisson ratio is greater than or equal to 0.35MPa, the preset area is a low ground stress and low elastic energy concentration area, the stress release holes are distributed in a single row, the diameter of each stress release hole is 300mm, the depth of each stress release hole is 4m, and the distance between two adjacent stress release holes is 4m;
If the elastic modulus is 5.5-16MPa, the cohesive force is 15-22KPa, the Poisson ratio is 0.2-0.35MPa, the preset area is a middle ground stress and middle elastic energy concentration area, the stress release holes are distributed in double rows, the diameter of each stress release hole is 400mm, the depth of each stress release hole is 4.5m, and the distance between every two adjacent stress release holes is 3.5;
if the elastic modulus is more than or equal to 16MPa, the cohesive force is more than or equal to 22KPa, the Poisson ratio is less than or equal to 0.2MPa, the preset area is a high ground stress and high elastic energy concentration area, the stress release holes are distributed in three rows, the diameter of each stress release hole is 500mm, the depth of each stress release hole is 5m, and the distance between every two adjacent stress release holes is 3m.
Description: by detecting the performance indexes, the engineering characteristics of the soil can be comprehensively known, so that scientific basis is provided for engineering design.
Further, in step S1, the diameter of the stress relief hole is determined to be 300-500mm, the depth of the stress relief hole is determined to be 4-5m, and the hole spacing between two adjacent stress relief holes is determined to be 3-4m.
Description: determining the diameter, depth of the stress relief holes and the hole spacing between two adjacent stress relief holes is important to ensure structural stability and to reduce residual stress, an appropriate diameter can help effectively cut and relieve residual stress within the structure while avoiding excessive damage to the structure, the depth of the holes determines the extent of the stress relief effect, an appropriate hole spacing can ensure that each hole works effectively while not weakening the overall performance of the structure due to too many holes, and careful consideration of these parameters must be taken in designing the stress relief holes to ensure that they cooperate to achieve optimal stress relief.
Further, in step S3, after a sufficient number of stress release holes are drilled, a plurality of sand piles are circumferentially distributed around the periphery of each stress release hole, and a sand pile ring is formed, and the construction process of the sand piles includes the following steps:
(1) Determining the position of each sand pile at the periphery of the stress release hole, rubbing back and forth by using a pipe rubbing machine, putting the steel sleeve into the designed pile bottom position to form a sand pile hole, pouring mortar into the steel sleeve, and uniformly pulling the steel sleeve while vibrating after filling to form a bottom layer sand pile;
(2) When the steel sleeve is pulled out, stopping when the bottom end of the steel sleeve is positioned at 1/3 of the upper end of the bottom layer sand pile, continuing to pour mortar into the steel sleeve, uniformly pulling out the steel sleeve after filling with mortar while vibrating to form a first middle layer sand pile, and then repeating the operations of pulling out the steel sleeve and pouring mortar to form a plurality of middle layer sand piles and upper layer sand piles, wherein when the upper layer sand piles are level with the ground, taking out the whole steel sleeve;
(3) Repeating the step (1) and the step (2) until the periphery of each stress release hole forms a sand pile ring;
Description: the sand pile rings are formed on the periphery of each stress release hole, so that the overall bearing capacity of a foundation can be enhanced, better drainage conditions are provided, the consolidation of soil bodies is promoted, and disturbance to the hole wall is reduced by a sectional construction method when the sand pile is manufactured, so that the unstable hole wall is reduced when the sand pile is constructed by a pipe twisting machine, the influence of each construction stage on the hole wall can be effectively controlled, and the disturbance of the soil bodies is reduced, so that the overall stability and bearing capacity of the sand pile are improved.
Further, in the step (1) and the step (2), the drawing rate of the steel sleeve is 0.5-0.8m/min, the diameter of the steel sleeve is 3-5cm, and the wall thickness of the steel sleeve is 6-7mm.
Description: the hollow or nonuniform phenomenon inside the sand pile can be effectively avoided by limiting the pulling rate of the steel sleeve, so that the bearing capacity and stability of the pile body are improved, the diameter of the steel sleeve directly determines the size of the formed hole, the proper diameter can ensure the size precision of the sand pile, the diameter and the thickness of the steel sleeve are limited, the sand pile can be ensured to maintain certain density and uniformity in the filling process, and the steel sleeve with proper thickness can provide enough supporting force to ensure that the sand pile can maintain good shape in the filling and tamping processes, so that the bearing capacity and the overall stability of the pile body are improved.
Further, in the step (1), before grouting mortar into the steel sleeve, reaming the bottom end of the sand pile hole by using a reaming bit to enable the bottom end size of the sand pile hole to be 1.5 times that of the upper end, backfilling concrete at the bottom end of the sand pile hole, and grouting mortar into the steel sleeve to form a bottom layer sand pile.
Description: by means of reaming the bottom end of the sand pile hole, the pile bottom area is increased, pile top load is dispersed, pile bottom stress concentration is reduced, the bearing capacity of the whole pile is improved, and the bearing characteristic of a soft foundation can be effectively improved by the aid of a pile-under-reaming technology, and the overall strength and stability of the pile are enhanced.
In step S2, the sealing film is made of high-density polyethylene, and when the vacuum pump is used to pump out the air under the sealing film to form a vacuum state, the vacuum degree at the lower end of the sealing film is between-10 KPa and-30 KPa.
Description: the combination of the sealing film and the vacuum pumping is used for accelerating the water drainage in the soil so as to promote the consolidation of the foundation, wherein the sealing film made of high-density polyethylene has good water resistance and enough mechanical strength, can bear the pressure and environmental influence in the construction process, and the vacuum degree at the lower end of the sealing film is in the range of-10 KPa to-30 KPa, so that the water can be promoted to flow to drainage facilities, and meanwhile, the adverse influence on the soil structure is avoided.
Further, in step S2, when the soil layers on the two sides of the isolation trench are frozen by using the freezing equipment, the freezing thickness of the soil layers is 5-6m, and the freezing strength is 4-5MPa.
Description: limiting the freezing thickness can ensure that a sufficiently firm frozen soil curtain is formed, which is helpful for improving the stability and bearing capacity of a soil layer and reducing the risk of ground subsidence, and setting the freezing strength to 4-5MPa can effectively prevent the frozen soil from excessively expanding in the thawing process, so that the risk of structural damage caused by frozen swelling is reduced.
Further, in step S4, the raw materials for forming the micro-expanding slurry include, in parts by weight: 40-50 parts of calcium carbonate, 20-25 parts of modified vermiculite powder, 1-2 parts of expansion cement, 1-3 parts of wood calcium, 0.4-0.5 part of polydimethylsiloxane and 0.5-0.8 part of carboxymethyl cellulose.
Description: among the above components, calcium carbonate is used to improve workability and reduce shrinkage of the slurry, modified vermiculite powder improves durability and stability of the slurry, expansive cement is used to ensure continuous and stable expansion of the slurry to compensate for post shrinkage of concrete, calcium lignan is used to improve fluidity of the slurry while reducing water usage, thereby reducing shrinkage and improving strength, polydimethylsiloxane is used to eliminate foam generated during stirring to ensure uniformity and stability of the slurry, carboxymethyl cellulose is used to maintain rheological properties of the slurry to avoid rapid precipitation or delamination, and the micro-expansive slurry is used together by these components to ensure good filling degree of the structure after grouting, limit expansion rate and corresponding mechanical properties such as compression resistance and flexural strength.
Compared with the prior art, the invention has the beneficial effects that:
According to the stress release hole construction method, the geological conditions are evaluated, the engineering characteristics of soil are fully known, scientific basis is provided for the layout of the stress release holes, before the stress release holes are selected, isolation trenches are excavated at the periphery of a layout area, so that the transmission of earth surface vibration waves caused by drilling can be effectively reduced and blocked, earth surface uplift is reduced, partial soil squeezing effect is relieved, meanwhile, the isolation trenches are treated by adopting a combination of vacuum pumping and freezing treatment, the movement of trench walls and the soil uplift caused by the extrusion of soil in the isolation trenches are prevented, the stability of the soil in the excavation and backfilling processes of the isolation trenches is effectively controlled, the preset area is divided into a plurality of subareas, the stress release holes are selected in each area, the stress release holes are reasonably distributed, the deformation of soil body can be better controlled, uneven settlement and ground uplift are prevented, and a large area is subdivided into a plurality of small areas, the construction risk of a single area is facilitated to be reduced, and once a certain area has a problem, the whole project is not affected immediately; the invention combines the technique of isolating grooves, drilling stress release holes in different areas and arranging sand pile rings, and can fully eliminate the soil squeezing effect generated during the construction of the stress release holes.
Drawings
Fig. 1 is a process flow diagram of the present invention.
Detailed Description
The present invention will be described in detail with reference to examples.
Example 1
As shown in fig. 1, a construction method of a safety type stress relief hole with a soil squeezing effect elimination comprises the following steps:
S1, evaluating geological conditions:
drilling and obtaining a soil sample in a preset area, performing laboratory test, determining possible high ground stress and high elastic energy concentration areas in a construction area according to the obtained test result, determining the number, the aperture and the layout area of stress release holes, and measuring the elastic modulus, the cohesive force and the poisson ratio of the soil sample when the obtained soil sample is subjected to laboratory test, wherein the test result shows that: the elastic modulus of the soil sample is 5.2MPa, the cohesive force is 13KPa, the Poisson ratio is 0.37MPa, the predetermined area is a low ground stress and low elastic energy concentration area, the stress release holes are distributed in a single row, the diameter of each stress release hole is 300mm, the depth of each stress release hole is 4m, and the distance between every two adjacent stress release holes is 4m;
S2, pre-pressing treatment of an isolation trench:
Cleaning sundries on the ground of a layout area, flattening the ground, excavating an isolation trench at the periphery of the layout area, paving a sand cushion layer with the thickness of 34cm in the isolation trench, paving a layer of sealing film at the upper end of the sand cushion layer, pumping air under the sealing film to form a vacuum state by using a vacuum pump, accelerating the water in soil to be pushed to drainage facilities and discharged due to the pressure difference between the inside and the outside of the sealing film, drilling a plurality of freezing holes into two sides of the isolation trench, pumping freezing pipes into the freezing holes, and freezing soil layers at two sides of the isolation trench by utilizing freezing equipment until the frozen soil layers reach the designed freezing thickness and the freezing strength; the sealing film is made of high-density polyethylene, when the vacuum pump is used for pumping air under the sealing film to form a vacuum state, the vacuum degree of the lower end of the sealing film is-10 KPa, and when the soil layers on the two sides of the isolation trench are frozen by using freezing equipment, the freezing thickness of the soil layers is 5m, and the freezing strength is 4MPa;
s3, drilling a stress release hole:
Cutting a preset area into a plurality of subareas, measuring and paying off in each subarea according to a construction drawing, determining drilling points of each stress release hole, erecting a drilling machine at the drilling points, enabling the center of the drilling machine and the center of the drilling points to be on the same plumb line, then drilling the stress release holes by using the drilling machine, controlling drilling depth according to platform elevation of the drilling machine, and repeating the steps until a sufficient number of stress release holes are drilled;
S4, reinforcing the stress release holes:
installing grouting pipes in the drilled stress release holes, tightly sealing the periphery of the grouting pipes, injecting micro-expansion slurry into the grouting pipes at the speed of 50mL/s, wherein the grouting pressure is 0.8Mpa, then cutting off the exposed grouting pipes, trowelling with cement slurry, and closing the grouting holes; the micro-expansion slurry comprises the following raw materials in parts by weight: 40 parts of calcium carbonate, 20 parts of modified vermiculite powder, 1 part of expansion cement, 1 part of wood calcium, 0.4 part of polydimethylsiloxane and 0.5 part of carboxymethyl cellulose.
Example 2
This embodiment differs from embodiment 1 in that:
In the step S2, cleaning sundries on the ground of a layout area, leveling the field, excavating an isolation trench at the periphery of the layout area, and paving a sand cushion layer with the thickness of 38cm in the isolation trench;
the elastic modulus, cohesive force and poisson ratio of the soil sample are measured, and the detection result shows that: the elastic modulus of the soil sample is 8.2MPa, the cohesive force is 18KPa, the Poisson ratio is 0.27MPa, the preset area is a middle ground stress and middle elastic energy concentration area, the stress release holes are distributed in double rows, the diameter of each stress release hole is 400mm, the depth of each stress release hole is 4.5m, and the distance between every two adjacent stress release holes is 3.5m
In the step S4, installing grouting pipes in the drilled stress release holes, tightly sealing the periphery of the grouting pipes, injecting micro-expansion slurry into the grouting pipes at the speed of 55mL/S, wherein the grouting pressure is 0.85Mpa, then cutting off the exposed grouting pipes, trowelling with cement slurry, and closing the grouting holes;
in the step S2, the sealing film is made of high-density polyethylene, and when the vacuum pump is used for pumping air under the sealing film to form a vacuum state, the vacuum degree of the lower end of the sealing film is-20 KPa;
in the step S2, when the soil layers at the two sides of the isolation trench are frozen by utilizing freezing equipment, the freezing thickness of the soil layers is 5.5m, and the freezing strength is 4.5MPa;
In step S4, the raw materials constituting the micro-expanding slurry include: 45 parts of calcium carbonate, 23 parts of modified vermiculite powder, 1.5 parts of expansion cement, 2 parts of wood calcium, 0.45 part of polydimethylsiloxane and 0.6 part of carboxymethyl cellulose.
Example 3
This embodiment differs from embodiment 1 in that:
in the step S2, cleaning sundries on the ground of a layout area, leveling the field, excavating an isolation trench at the periphery of the layout area, and paving a sand cushion layer with the thickness of 40cm in the isolation trench;
The elastic modulus, cohesive force and poisson ratio of the soil sample are measured, and the detection result shows that: the elastic modulus of the soil sample is 20MPa, the cohesive force is 24KPa, the Poisson ratio is 0.17MPa, the preset area is a high ground stress and high elastic energy concentration area, the stress release holes are distributed in three rows, the diameter of each stress release hole is 500mm, the depth of each stress release hole is 5m, and the distance between every two adjacent stress release holes is 3m;
In the step S4, installing grouting pipes in the drilled stress release holes, tightly sealing the periphery of the grouting pipes, injecting micro-expansion slurry into the grouting pipes at the rate of 60mL/S, wherein the grouting pressure is 0.9Mpa, then cutting off the exposed grouting pipes, trowelling with cement slurry, and closing the grouting holes;
In the step S2, the sealing film is made of high-density polyethylene, and when the vacuum pump is used for pumping air under the sealing film to form a vacuum state, the vacuum degree of the lower end of the sealing film is-30 KPa;
In the step S2, when the soil layers at the two sides of the isolation trench are frozen by utilizing freezing equipment, the freezing thickness of the soil layers is 6m, and the freezing strength is 5MPa;
In step S4, the raw materials constituting the micro-expanding slurry include: 50 parts of calcium carbonate, 25 parts of modified vermiculite powder, 2 parts of expansion cement, 3 parts of wood calcium, 0.5 part of polydimethylsiloxane and 0.8 part of carboxymethyl cellulose.
Example 4
This embodiment differs from embodiment 3 in that:
in step S3, after drilling a sufficient number of stress release holes, distributing a plurality of sand piles along the circumferential direction at the periphery of each stress release hole, and forming a sand pile ring, and the construction process of the sand piles comprises the following steps:
(1) Determining the position of each sand pile at the periphery of the stress release hole, rubbing back and forth by using a pipe rubbing machine, putting the steel sleeve into the designed pile bottom position to form a sand pile hole, pouring mortar into the steel sleeve, and uniformly pulling the steel sleeve while vibrating after filling to form a bottom layer sand pile;
(2) When the steel sleeve is pulled out, stopping when the bottom end of the steel sleeve is positioned at 1/3 of the upper end of the bottom layer sand pile, continuing to pour mortar into the steel sleeve, uniformly pulling out the steel sleeve after filling with mortar while vibrating to form a first middle layer sand pile, and then repeating the operations of pulling out the steel sleeve and pouring mortar to form a plurality of middle layer sand piles and upper layer sand piles, wherein when the upper layer sand piles are level with the ground, taking out the whole steel sleeve;
(3) Repeating the step (1) and the step (2) until the periphery of each stress release hole forms a sand pile ring;
In the step (1) and the step (2), the pulling rate of the steel sleeve is 0.5m/min, the diameter of the steel sleeve is 3cm, and the wall thickness is 6mm;
In the step (1), before grouting mortar into the steel sleeve, reaming the bottom end of the sand pile hole by using a reaming bit to enable the bottom end size of the sand pile hole to be 1.5 times that of the upper end, backfilling concrete at the bottom end of the sand pile hole, and grouting mortar into the steel sleeve to form a bottom sand pile.
Example 5
This embodiment differs from embodiment 4 in that:
In the step (1) and the step (2), the drawing rate of the steel sleeve is 0.7m/min, the diameter of the steel sleeve is 4cm, and the wall thickness of the steel sleeve is 6.5mm.
Example 6
This embodiment differs from embodiment 4 in that:
in the step (1) and the step (2), the drawing rate of the steel sleeve is 0.8m/min, the diameter of the steel sleeve is 5cm, and the wall thickness is 7mm.
Test examples
When the obtained soil sample is detected in a laboratory, the elastic modulus, the cohesive force and the poisson ratio of the soil sample are measured, the detected elastic modulus is more than or equal to 16MPa, the cohesive force is more than or equal to 22KPa, the area with the poisson ratio less than or equal to 0.2MPa is regarded as a high ground stress and high elastic energy concentration area, the area is regarded as a test area, then the test area is divided into 3 test areas, namely a test I area and a test III area from right to left, and the hole positions of stress release holes corresponding to the test I area and the test III area are distributed as follows:
Test I region: adopting single-row arrangement, wherein each row comprises 15 stress release holes, the diameter of each stress release hole is 300mm, the depth of each stress release hole is 4m, and the distance between two adjacent stress release holes is 4m;
Test II region: the double rows are adopted, each row of 15 stress release holes are distributed, the diameter of each stress release hole is 400mm, the depth of each stress release hole is 4.5m, and the distance between every two adjacent stress release holes is 3.5;
Test III region: three rows of 15 stress release holes are distributed, the diameter of each stress release hole is 500mm, the depth of each stress release hole is 5m, and the distance between two adjacent stress release holes is 3m;
The horizontal displacement and the vertical displacement of the earth surface of the test I region-III region are monitored through a full-automatic monitor and an earth surface fixed Lecia Nova TS-60 prism, the horizontal displacement and the vertical displacement data of the earth surface are measured and recorded by using a USR-G780 wireless bidirectional transmission module, and the table 1 is obtained according to the detected test data:
Table 1: surface horizontal displacement and surface vertical displacement data table for test I region-III region
As can be seen from Table 1, when the test area is a high-ground stress and high-elastic energy concentrated area, the arrangement condition of the hole positions of the stress release holes in the test area I enables the ground surface horizontal displacement amount and the ground surface vertical displacement of the soil to be highest, and the arrangement condition of the hole positions of the stress release holes in the test area III enables the ground surface horizontal displacement amount and the ground surface vertical displacement of the soil to be lowest, so that when the elastic modulus of the soil in the test area is more than or equal to 16MPa, the cohesive force is more than or equal to 22KPa, the Poisson ratio is less than or equal to 0.2MPa, the isolation effect is optimal by adopting the arrangement condition of the hole positions of the stress release holes in the test area III, and the effect of eliminating the soil squeezing effect is best.
Claims (9)
1. The construction method of the safe stress release hole with the effect of eliminating soil compaction is characterized by comprising the following steps of:
S1, evaluating geological conditions:
Drilling and obtaining a soil sample in a preset area, performing laboratory test, determining possible high ground stress and high elastic energy concentration areas in a construction area according to the obtained test result, and determining the number, the aperture and the layout area of stress release holes;
S2, pre-pressing treatment of an isolation trench:
Cleaning sundries on the ground of a layout area, flattening the ground, excavating an isolation trench at the periphery of the layout area, paving a sand cushion layer with the thickness of 34-40cm in the isolation trench, paving a layer of sealing film at the upper end of the sand cushion layer, pumping air under the sealing film to form a vacuum state by using a vacuum pump, accelerating the water in the soil to push to a drainage facility and discharge the water due to the pressure difference between the inside and the outside of the sealing film, drilling a plurality of freezing holes at two sides of the isolation trench, pumping freezing pipes into each freezing hole, and freezing soil layers at two sides of the isolation trench by utilizing freezing equipment until the frozen soil layers reach the designed freezing thickness and the freezing strength;
s3, drilling a stress release hole:
Cutting a preset area into a plurality of subareas, measuring and paying off in each subarea according to a construction drawing, determining drilling points of each stress release hole, erecting a drilling machine at the drilling points, enabling the center of the drilling machine and the center of the drilling points to be on the same plumb line, then drilling the stress release holes by using the drilling machine, controlling drilling depth according to platform elevation of the drilling machine, and repeating the steps until a sufficient number of stress release holes are drilled;
S4, reinforcing the stress release holes:
And installing grouting pipes in the drilled stress release holes, tightly sealing the periphery of the grouting pipes, injecting micro-expansion slurry into the grouting pipes at the rate of 50-60mL/s, wherein the grouting pressure is 0.8-0.9Mpa, cutting off the exposed grouting pipes, trowelling with cement slurry, and closing the grouting holes.
2. The method for constructing a safety type stress relief hole with a soil squeezing effect according to claim 1, wherein in step S1, the modulus of elasticity, cohesion and poisson' S ratio of the soil sample are measured when laboratory test is performed on the obtained soil sample.
3. The construction method of a safe type stress relief hole with soil compaction effect elimination according to claim 1, wherein in the step S1, the diameter of the determined stress relief hole is 300-500mm, the depth of the stress relief hole is 4-5m, and the hole spacing between two adjacent stress relief holes is 3-4m.
4. The construction method of a safety type stress relief hole with soil compaction effect elimination according to claim 1, wherein in step S3, after a sufficient number of stress relief holes are drilled, a plurality of sand piles are circumferentially distributed around each stress relief hole, and a sand pile ring is formed, and the construction process of the sand piles comprises the steps of:
(1) Determining the position of each sand pile at the periphery of the stress release hole, rubbing back and forth by using a pipe rubbing machine, putting the steel sleeve into the designed pile bottom position to form a sand pile hole, pouring mortar into the steel sleeve, and uniformly pulling the steel sleeve while vibrating after filling to form a bottom layer sand pile;
(2) When the steel sleeve is pulled out, stopping when the bottom end of the steel sleeve is positioned at 1/3 of the upper end of the bottom layer sand pile, continuing to pour mortar into the steel sleeve, uniformly pulling out the steel sleeve after filling with mortar while vibrating to form a first middle layer sand pile, and then repeating the operations of pulling out the steel sleeve and pouring mortar to form a plurality of middle layer sand piles and upper layer sand piles, wherein when the upper layer sand piles are level with the ground, taking out the whole steel sleeve;
(3) And (3) repeating the step (1) and the step (2) until the periphery of each stress release hole forms a sand pile ring.
5. The construction method of a safe type stress relief hole with soil compaction effect elimination according to claim 4, wherein in the step (1) and the step (2), the pulling rate of the steel sleeve is 0.5-0.8m/min, the diameter of the steel sleeve is 3-5cm, and the wall thickness is 6-7mm.
6. The construction method of a safety type stress relief hole for eliminating soil squeezing effect according to claim 4, wherein in step (1), before grouting mortar into the steel casing, reaming the bottom end of the sand pile hole with a reamer bit to make the bottom end size of the sand pile hole 1.5 times the upper end size, then backfilling concrete at the bottom end of the sand pile hole, and then grouting mortar into the steel casing to form a bottom layer sand pile.
7. The construction method of a safe type stress relief hole with soil squeezing effect eliminating effect according to claim 1, wherein in step S2, the sealing film is made of high density polyethylene, and when the vacuum pump is used to pump out the air under the sealing film to form a vacuum state, the vacuum degree of the lower end of the sealing film is-10 KPa to-30 KPa.
8. The construction method of a safe type stress relief hole with soil squeezing effect eliminating effect according to claim 1, wherein in step S2, when the soil layers at both sides of the isolation trench are frozen by using freezing equipment, the freezing thickness of the soil layers is 5-6m, and the freezing strength is 4-5MPa.
9. The method for constructing a safety type stress relief hole with a soil squeezing effect eliminated as claimed in claim 1, wherein in step S4, the raw materials constituting the micro-expansive slurry include, in parts by weight: 40-50 parts of calcium carbonate, 20-25 parts of modified vermiculite powder, 1-2 parts of expansion cement, 1-3 parts of wood calcium, 0.4-0.5 part of polydimethylsiloxane and 0.5-0.8 part of carboxymethyl cellulose.
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