CN-121976515-A - Underground solidification constraint pressurization combined vacuum preloading sludge reinforcement soft soil construction method

CN121976515ACN 121976515 ACN121976515 ACN 121976515ACN-121976515-A

Abstract

The invention discloses an underground solidification constraint pressurization combined vacuum preloading reinforcement silt soft soil construction method which comprises the steps of forming an underground constraint structure consisting of a shallow solidified soil layer and a peripheral sealing solidified wall in a soft soil area to be reinforced, arranging a drainage channel and a plurality of pressurization air bags in soft soil in the constraint structure, connecting the pressurization air bags with ground pressurization equipment through pressurization pipelines, paving a sealing covering system on the ground surface, connecting the sealing covering system with the drainage channel, carrying out vacuum preloading, actively applying gas pressure in the pressurization air bags through the ground pressurization equipment during or after the vacuum preloading to enable the air bags to expand and apply additional load to surrounding soft soil, and pouring solidified slurry into the pressurization air bags through the pressurization pipelines after the pressurization and the vacuum preloading are stopped to enable the pressurization air bags to form permanent reinforcement bodies in the soft soil. The invention improves the effective consolidation stress acting on soft soil, thereby accelerating drainage, improving deep reinforcement effect and final foundation bearing capacity.

Inventors

SHAO JICHENG
WU DI
Xue Ruopu
FAN CHAO
JIANG ZHIQUAN
WANG LEI
DENG BINGJIE
HE TAO
BAI YE
YIN LIJING

Assignees

中交第二航务工程局有限公司

Dates

Publication Date: 20260505
Application Date: 20260121

Claims (9)

1. The construction method for reinforcing the silt soft soil by combining underground solidification, constraint and pressurization and vacuum preloading is characterized by comprising the following steps of: s1, forming an underground constraint structure consisting of a shallow solidified soil layer and a peripheral sealed solidified wall in a soft soil area to be reinforced; s2, arranging a drainage channel and a plurality of pressurizing air bags in soft soil in the constraint structure, wherein the pressurizing air bags are connected with ground pressurizing equipment through pressurizing pipelines; s3, paving a sealing cover system on the surface of the field, connecting the sealing cover system with the drainage channel, and performing vacuum preloading; S4, actively applying gas pressure into the pressurizing air bag through the ground pressurizing equipment in the vacuum preloading process or after the vacuum preloading process, so that the air bag is inflated and additional load is applied to surrounding soft soil; S5, after pressurizing and vacuum preloading are stopped, pouring solidified slurry into the pressurizing air bag through the pressurizing pipeline, so that the pressurizing air bag forms a permanent reinforcing body in soft soil.
2. The method for constructing the underground curing, constraining and pressurizing combined vacuum preloading reinforced silt soft soil according to claim 1, wherein the thickness of the shallow cured soil layer is 1.5-3 m, the width of the sealing cured wall is 1-2 m, and the depth is 5-12 m, and the shallow cured soil layer and the sealing cured wall are formed by in-situ curing of a soft soil curing agent.
3. The method for constructing the underground solidification, restriction and pressurization combined vacuum preloading and sludge reinforcement soft soil according to claim 1, wherein the pressurization air bag is made of natural rubber, is ellipsoidal after being inflated, has the length of 3m, has the middle diameter of 50cm and can bear the pressure of 0.2 MPa; The pressurizing air bags are arranged in a grid shape in soft soil, the distance is 2-4 m, and the burying depth is 6-15 m.
4. The method for constructing the soft soil by combining underground solidification, constraint and pressurization and vacuum preloading reinforcement of silt is characterized in that the gas pressure applied to a pressurizing air bag in the step S4 is 0.15-0.2 MPa, and the method is implemented in a staged pressurizing mode, wherein the air bag pressure is firstly increased to 0.08-0.10 MPa within 1 hour and stabilized for a certain time, and then the pressure is increased to 0.15-0.2 MPa within 1 hour; According to the initial water content or the aperture ratio of the soft soil below the shallow solidified soil layer, dynamically adjusting the pressure stabilizing time in the step of graded pressurization of the pressurizing air bags: when the initial water content of soft soil is more than 75% or the aperture ratio is more than 1.8, the pressure stabilizing time of the pressure of 0.08-0.10 MPa is prolonged to 8-12 hours; when the initial water content of the soft soil is less than or equal to 75 percent and the pore ratio is less than or equal to 1.8, the soft soil is subjected to conventional voltage stabilizing time of 4-8 hours.
5. The method for constructing the soft soil by combining underground solidification, constraint and pressurization and vacuum preloading reinforcement of silt, as set forth in claim 1, is characterized in that in the step S4, before the sealing film is paved, one or more vacuum measuring heads are placed at preset monitoring points, the vacuum degree under the film is monitored in real time while the pressurizing air bag is pressurized, if the vacuum degree under the film is reduced by more than 5kPa, the pressure of the air bag is temporarily increased, and the pressurizing is continued after the vacuum degree is restored; If the submembrane vacuum has not recovered to the pre-descent level for more than 2 hours after the boost bladder pressure has been temporarily raised, the following operations are performed: a) Actively reducing the pressure of the air bag by 0.02-0.03 MPa; b) Maintaining the reduced pressure, and continuing vacuum pumping until the vacuum degree under the membrane is stably recovered; c) Starting from the current pressure again, the staged pressurization process continues.
6. The method for constructing the soft soil by combining underground solidification, constraint and pressurization and vacuum preloading reinforcement of silt according to claim 1, wherein in the step S5, before injecting solidification slurry into the pressurization air bag, cement paste or solidifying agent diluent is injected into the air bag through a pressurization pipeline, the injection volume is 10% -15% of the estimated volume of the air bag, the low pressure circulation of the pressurization pump is maintained for 1-2 hours, and then the solidification slurry is formally injected.
7. The method for constructing the underground solidification, restriction and pressurization combined vacuum preloading reinforced silt soft soil according to claim 1, wherein the drainage channel comprises plastic drainage plates and vacuum suction filtration branch pipes, the plastic drainage plates are arranged in a regular triangle or square shape, and the distance is 0.8-1.2 m.
8. The method for constructing the soft soil by combining underground solidification, constraint and pressurization and vacuum preloading reinforcement of silt according to claim 1, wherein the construction of the sealing solidification wall and the construction of the plastic drainage plate are performed synchronously or alternately, and the exposed part of the drainage plate is tightly paved on the solidification wall surface at the junction of the drainage plate and the solidification wall and is temporarily fixed by an adhesive.
9. The method for constructing the soft soil by combining underground solidification, constraint and pressurization and vacuum preloading reinforcement sludge is characterized in that in the step S3, when vacuum preloading is carried out, the method enters vacuum constant pressure maintenance after the vacuum degree under the membrane reaches 85kPa and is stably maintained for 3 days, and the vacuum degree under the membrane in the whole vacuum preloading process is larger than 85kPa; After the vacuum degree under the film is stabilized above 85kPa for 7 days, light equipment walking or material stacking operation can be performed on the surface of the shallow solidified soil.

Description

Underground solidification constraint pressurization combined vacuum preloading sludge reinforcement soft soil construction method Technical Field The invention relates to the technical field of geotechnical engineering foundation treatment. More particularly, the invention relates to a soft soil construction method for reinforcing silt by combining underground solidification, constraint and pressurization and vacuum preloading. Background Deep and high-water-content silt layers are distributed underground in coastal areas of China, and due to the fact that the water content is high, the porosity is high and the like, the bearing capacity of the silt foundation is low, if the silt foundation is improperly treated, large sedimentation or uneven sedimentation occurs easily, the use effect of projects such as buildings, bridges and highways is affected to a certain extent, and even the structure of the projects is damaged. The vacuum preloading technology is widely applied to large-area high-water-content sludge treatment, and is characterized in that a drain board is arranged in a sludge layer, then a sand cushion layer, a vacuum drainage system, geotextiles and a sealing film are sequentially paved, air under the film and groundwater are pumped out through a jet pump, the sludge layer is preloaded and drained by utilizing atmospheric pressure, and the bearing capacity of a foundation is increased. Engineering practice shows that the type of sludge is easy to generate the following problems when vacuum preloading is carried out, namely (1) the equivalent consolidation load applied to the soil body is usually less than 85kPa due to the limitation of atmospheric pressure, the sludge treatment effect is limited, (2) the drain plate is easy to generate silting during vacuum preloading, the negative pressure is in a rapid attenuation trend along the depth direction, the deep sludge treatment effect is poor, and (3) the permeability coefficient of the soil body is greatly reduced and the water volume discharged by soil body consolidation is small and the treatment efficiency is obviously reduced in the later stage of vacuum preloading. The preloading is also used for treating high-water-content silt soil, when soft soil is treated, a drain board is firstly arranged in the soft soil or a drain sand well is arranged, a large amount of heavy objects are piled on the surface layer of the soft soil, and the soft soil is solidified and drained by utilizing the weight of the piled objects, so that the purpose of reinforcing the soft soil foundation is achieved. Practice shows that the preloading has the following problems that (1) a certain engineering project lacks the preloading objects such as sand, soil and the like on site, a large amount of sand, soil and the like are needed to be purchased to be used as the preloading objects, the post-heavy object unloading and post-treatment work is added, the engineering cost is greatly increased, the construction period is prolonged, and (2) the silt with higher water content is easily sheared and damaged even if the grading preloading is adopted. In addition, the vacuum preloading and the preloading technology are commonly used in combination in engineering, namely, the vacuum preloading is combined with preloading to treat soft soil foundations, and the technology also has the two defects. Therefore, development of a new method for treating soft soil foundation capable of effectively improving reinforcement load and enhancing deep treatment effect and simultaneously having economical efficiency and construction convenience is needed. Disclosure of Invention The invention aims to overcome the defects of the existing vacuum preloading and preloading technology and provides a method for constructing soft soil by combining underground solidification constraint pressurization and vacuum preloading reinforcement silt. The method aims at improving the effective consolidation stress acting on the soft soil by actively applying controllable gas pressure in the underground soft soil and combining a space constraint structure, thereby accelerating drainage, improving the deep reinforcement effect and the final foundation bearing capacity. The technical scheme adopted by the invention for solving the technical problem is that the construction method for reinforcing the silt soft soil by combining underground solidification constraint pressurization and vacuum preloading comprises the following steps: s1, forming an underground constraint structure consisting of a shallow solidified soil layer and a peripheral sealed solidified wall in a soft soil area to be reinforced; s2, arranging a drainage channel and a plurality of pressurizing air bags in soft soil in the constraint structure, wherein the pressurizing air bags are connected with ground pressurizing equipment through pressurizing pipelines; s3, paving a sealing cover system on the surface of the field, connecting the sealing cover s