CN-115977060-B - Interactive precipitation vacuum combined preloading reinforcement deep soft foundation system and method thereof

CN115977060BCN 115977060 BCN115977060 BCN 115977060BCN-115977060-B

Abstract

The invention discloses an interactive precipitation vacuum combined preloading reinforcement deep soft foundation system and a method thereof. According to the method, the dewatering well is arranged in vacuum preloading, and the vacuum pump of the dewatering well is periodically switched on and off to communicate with the atmosphere, so that an interactive dewatering effect is formed between the dewatering well and the drainage plate. In the process of communicating the dewatering well with the atmosphere, a vacuum pressure gradient is formed on the soil body between the dewatering well and the drainage plate, so that a hydraulic gradient is formed between the dewatering well and the drainage plate, the clogging effect of the drainage plate is greatly improved, and the dewatering effect of the dewatering well is improved. The treatment method has the advantages that the foundation of deep soft soil is improved greatly, the construction period can be shortened, and the construction and maintenance cost can be reduced. The method is simple in process and convenient to implement, and can be used for actual engineering.

Inventors

DENG YONGFENG
XU CHENCHEN
ZHU XIANGYANG
HU YONGTAO
LU YOUBING
CHENG DA
HAN SHIJIE
RUAN CHUNSHENG

Assignees

东南大学
连云港港口集团有限公司
中交第三航务工程勘察设计研究院有限公司

Dates

Publication Date: 20260505
Application Date: 20220824

Claims (6)

1. A method for reinforcing a deep soft foundation by interactive precipitation vacuum combined preloading is realized based on an interactive precipitation vacuum combined preloading reinforcing deep soft foundation system and is characterized in that the interactive precipitation vacuum combined preloading reinforcing deep soft foundation system comprises drainage plates, precipitation wells, water level observation wells and control switches, wherein the drainage plates and the precipitation wells are vertically and uniformly distributed in a deep soft soil foundation, the distribution depth of pipes of the drainage plates is larger than the distribution depth of the precipitation wells, the pipe diameter of each drainage plate is smaller than the pipe diameter of each precipitation well, and simultaneously, the periphery of each precipitation well is uniformly distributed with the pipes of a plurality of drainage plates; the method for reinforcing the deep soft foundation by combining interactive precipitation and vacuum preloading comprises the following steps of: Firstly, vertically and uniformly arranging a plurality of drain boards and dewatering wells in a soft soil foundation according to set intervals, wherein the arrangement depth of the drain boards is larger than that of the dewatering wells; step two, connecting a water pumping pipeline of the drain board to a vacuum pump A and a water pumping pipeline of the dewatering well to a vacuum pump B, wherein the vacuum pump A and the vacuum pump B work independently of each other so as to perform independent on-off control and control on the atmosphere communicated with the dewatering well; step three, vacuumizing the corresponding drain plate and the dewatering well through the vacuum pump A and the vacuum pump B respectively; step four, carrying out preloading on the soft soil foundation; Step five, when the vacuum degree in the water pumping pipeline of the drain board and the water pumping pipeline of the dewatering well is stable, and the water outlet and air outlet amounts of the vacuum pump A and the vacuum pump B are reduced, the vacuum pump B is closed; Step six, communicating a water pumping pipeline of the dewatering well with the outside atmosphere to ensure that the air pressure at the position of the dewatering well is the atmospheric pressure, and communicating the water pumping pipeline of the drainage plate with the vacuum pump A to ensure that the air pressure at the position of the drainage plate is- At the moment, a vacuum pressure gradient is formed in the soil between the drainage plate and the dewatering well, groundwater is promoted to gather towards the drainage plate, the groundwater flows to the drainage plate from the position of the dewatering well, and the groundwater level is lowered; And step seven, when the water outlet rate of groundwater flowing from the precipitation well position to the drain board is reduced and the water outlet amount is reduced, closing the communication between the water pumping pipeline of the precipitation well and the external atmosphere, then opening the vacuum pump B to perform vacuum pumping treatment on the precipitation well until the vacuum degree in the precipitation well is stable, closing the vacuum pump B when the water outlet amount and the water outlet amount of the vacuum pump B are reduced, repeating the step six and the step seven until the preset water outlet level is reached, unloading and finishing construction.
2. The method for reinforcing a deep soft foundation by combining interactive precipitation and vacuum preloading according to claim 1, wherein a water level observation well is arranged at a key node of a construction site, the time for switching on and switching off a vacuum pump B of a precipitation well and communicating with the atmosphere environment is controlled by the water level, when the water outlet rate of groundwater flowing from the precipitation well position to a drain board is reduced, the vacuum pump of the precipitation well is closed, the atmosphere is communicated, the groundwater is promoted to flow from the precipitation well position to the drain board, the water level observation well is subjected to atmospheric pressure at the moment to reduce the water level, the water level slowly rises and becomes gentle along with the time of the precipitation well communicating with the atmosphere, and when the water level reaches a fixed value, the vacuum pump of the precipitation well is opened for vacuumizing, and the period is taken.
3. The method for reinforcing a deep soft foundation by combining interactive precipitation and vacuum preloading according to claim 2, wherein the water level observation well adopts sealed sampling, and the inaccurate water level reading of the water level observation well caused by the fact that atmospheric pressure is communicated with the water level observation well is avoided.
4. The method for reinforcing the deep soft foundation by the interactive precipitation vacuum combined preloading is characterized in that construction is carried out in stages, conventional vacuum preloading air suction is carried out on a drainage plate and a precipitation well in the initial stage of the construction, the drainage is promoted when the drainage plate and the precipitation well reach a sufficient vacuum environment, the drainage rate is slowed down in the middle stage of the construction, the precipitation well is periodically communicated with the atmosphere, the vacuum pressure gradient of the soft foundation is improved, and the drainage is accelerated.
5. The method for reinforcing a deep soft foundation by interactive precipitation vacuum combined preloading is characterized in that a filter screen is arranged at the lower end of a pipe of a drain board, the width of the drain board is 100+/-2 mm, the thickness of the drain board is 3.5-6.0+/-0.5 mm, the depth is not less than 20m, leakage holes are distributed on the wall of a precipitation well pipe, a filter cloth is wrapped on the surface layer of the precipitation well pipe, the filter screen is arranged at the lower end of the pipe, the aperture is 300mm, and the depth is not less than 10m.
6. The method for reinforcing the deep soft foundation by the interactive precipitation vacuum combined preloading is characterized in that the surface of the deep soft foundation is covered with a sealing film, a drain board, a precipitation well, a water pumping pipeline A and a water pumping pipeline B are all covered below the sealing film, and the piling is arranged on the outer side of the sealing film.

Description

Interactive precipitation vacuum combined preloading reinforcement deep soft foundation system and method thereof Technical Field The invention relates to an interactive precipitation vacuum combined preloading reinforcement deep soft foundation system and a method thereof, belonging to the technical field of foundation engineering construction process. Background With the rapid development of coastal cities and the increase of population in China, land resources become more and more scarce. Sea reclamation is an effective way to solve the problem of shortage in coastal areas of the world, so that projects such as port construction, beach construction and the like are increasingly increased. In practice, mud excavated from the seabed near a sea-fill site is generally used as a sea-fill material, and soft soil involved in such engineering has the characteristics of high water content, deep soft soil foundation, high compressibility and the like. The vacuum preloading is widely applied as a common economical and reliable drainage consolidation method, and the traditional vacuum preloading combined preloading can have a good effect when shallow soft soil is reinforced. However, in the aspect of reinforcing the deep soft soil, the vacuum preloading combined stacking scheme has a plurality of defects that firstly, the drainage consolidation time is relatively long, the sedimentation rate is difficult to stabilize, the sedimentation after construction is difficult to evaluate, the construction time is prolonged, secondly, the additional stress caused by the preloading load is attenuated along with the depth, the reinforcing effect on the deep soft soil is not ideal, and the treatment depth is limited. Along with the increase of the reinforcement depth, the vacuum degree is attenuated, the effective depth is limited, about 10m is generally, the soft soil lying down can not be effectively solidified, and large-scale vertical settlement and horizontal displacement deformation in the later period of engineering are easily caused, so that the promotion of the engineering and the reduction of the construction maintenance cost are not facilitated. In summary, according to the current practical situation and technical conditions, it is highly desirable to invent a foundation reinforcement method for deep soft soil, so as to reduce construction cost, shorten construction period, reduce the effect of post-settlement deformation damage, and promote the effective reinforcement effect of deep soft soil foundation reinforcement. Disclosure of Invention The invention aims to provide an interactive precipitation-vacuum combined pile-up reinforcement scheme for reinforcing a deep soft foundation, and the treatment method has a great improvement on the foundation reinforcement effect of the deep soft soil (the thickness is more than 10 m), and can shorten the construction period and reduce the construction and maintenance cost. The method is reasonable in technology, and can solve the problems of insufficient reinforcement depth, insufficient stacking and loading, overhigh stacking and loading cost, long construction period and the like in the traditional vacuum-combined stacking and loading scheme. In order to achieve the technical purpose, the invention adopts the following technical scheme: an interactive dewatering vacuum combined preloading deep soft foundation reinforcement system is used for reinforcing a deep soft soil foundation and comprises drainage plates and dewatering wells, wherein the drainage plates and the dewatering wells are vertically and uniformly distributed in the deep soft soil foundation, the distribution depth of pipes of the drainage plates is larger than that of the dewatering wells, the pipe diameter of the drainage plates is smaller than that of the dewatering wells, and a plurality of pipes of the drainage plates are uniformly distributed around each dewatering well; the drainage plates are converged through the water pumping pipeline A and then are communicated with the vacuum pump A and the external atmosphere, the dewatering wells are converged through the water pumping pipeline B and then are communicated with the vacuum pump B, and the vacuum pump A and the vacuum pump B work independently. Preferably, the lower end of the pipe of the drain plate is provided with a filter screen. Preferably, the pipe wall of the dewatering well is provided with weeping holes, the surface layer is wrapped with filter cloth, and the lower end of the pipe is provided with a filter screen. Preferably, the surface of the deep soft soil foundation is covered with a sealing film, the drain board, the dewatering well, the water pumping pipeline A and the water pumping pipeline B are all covered below the sealing film, and the outer side of the sealing film is provided with a stacking load. Preferably, a water level observation well is also arranged in the deep soft soil foundation, the water pumping pipeline A is respe