CN103015399A - Earthquake disaster reduction system for liquefiable foundation and foundation treatment method - Google Patents

Abstract

The invention discloses an earthquake resistance and disaster reduction system for a liquefiable foundation. A permanent vertical hole pressure dissipation drainage body and a horizontal hole pressure dissipation drainage body are arranged in the liquefiable foundation. The vertical hole pressure dissipation drainage body and the horizontal hole pressure dissipation The drainage body communicates and connects with the surface drainage system. According to the method, a permanent excess pore water pressure dissipating channel is set for the liquefiable foundation, the excess static pore water pressure is controlled and reduced, and the source of liquefaction is prevented, thereby improving the anti-seismic liquefaction performance of the foundation. The dissipating channel can be arranged before the foundation reinforcement. During the construction period, it will be used as a drainage system for foundation treatment, and after the construction period is completed, it will be used as a permanent ultra-static pore water pressure dissipation channel. It can also be arranged after the foundation is strengthened as a permanent facility during the operation period.

Description

Earthquake resistance and disaster reduction system for liquefiable foundation and foundation treatment method

technical field

The invention relates to the technical field of soft soil foundation treatment such as port engineering, traffic engineering, construction engineering and highway engineering.

Background technique

With the continuous and rapid development of my country's economy, the scale of infrastructure construction in my country's coastal areas in recent years has been unprecedented. A large number of land reclamation projects have been carried out.

Most of these projects are filled with waste silt, fine sand, silt and other materials by hydraulic blowing on the silted tidal flats, and then carry out foundation reinforcement treatment. Due to the unprecedented scale of my country's land reclamation projects, dredging and reclamation resources are increasingly in short supply, especially medium-coarse sand with good earthquake resistance and liquefaction, which is already facing the situation of no sand available in many places. In view of this situation, More and more projects use locally abundant silt and fine sand, such as Tianjin Lingang and Caofeidian. The engineering characteristic of this type of dredging filling material that has the greatest impact on the project is the problem of liquefaction. In addition, these coastal areas generally have deep silt layers, sand layers, silt layers, and clay layers widely distributed under the dredging fill soil. The liquefaction of the original saturated silt and fine sand and silt under the action of earthquake is a worldwide problem, especially after the project is completed and the superstructure is in operation.

Under the action of the horizontal vibration generated by the earthquake, the position of the soil will be adjusted and tend to be compacted, and the compaction of the soil will inevitably eliminate pore water. Under the action of sharp cyclical dynamic load, if the water permeability of the soil is poor and the drainage is not smooth, the drainage in the previous cycle has not been completed, and the drainage in the next cycle will be drained. The water that should be drained is too late to be discharged, and the water It is incompressible again, so excess pore water pressure is produced, and the shear strength of sandy soil is greatly reduced at this time. As the vibration time continues, the excess pore water pressure continues to accumulate and superimpose and increase, and finally the shear strength of the soil is completely lost. This phenomenon is called liquefaction.

Sand liquefaction, as a major form of earthquake disasters, often causes uneven settlement of building foundations and structural damage, such as: sandblasting flow soil, embankment slide, ground cracking and sinking, building cracking and collapse, Wharf damage, etc., caused serious disasters and casualties, and brought huge disasters to mankind.

An increase in excess pore water pressure is a necessary condition for liquefaction to occur. Reducing the pore water pressure of saturated sand and silt under the action of external force, especially periodic force is an important way to solve the liquefaction.

Contents of the invention

The invention aims to provide an effective, convenient and cost-saving method applied to liquefiable foundations to improve earthquake resistance and disaster reduction performance.

In order to achieve the above object, the present invention adopts the following technology: an earthquake-resistant and disaster-mitigating system for liquefiable foundations, which is characterized in that a permanent vertical pore pressure dissipating drainage body and a horizontal pore pressure dissipating drainage body are set in the liquefiable foundation. The pore pressure dissipating drainage body communicates with the horizontal pore pressure dissipating drainage body and connects with the surface drainage system.

The vertical pore pressure dissipating drainage body penetrates to reach the sandy soil or silt layer of the liquefiable foundation.

The horizontal pore pressure dissipating drainage body is laid on the stable layer of foundation settlement, or the liquefiable sand or silt layer, so as to prevent the displacement of the foundation from destroying the horizontal pore pressure dissipating drainage body.

Specifically, the vertical pore pressure dissipating drainage body is selected from one or more drainage materials selected from water collection wells, tube wells, vertical plastic drainage boards, cardboards, sand piles, bagged sand wells, and sandstone piles. .

Specifically, the horizontal pore pressure dissipation drainage body is selected from sand, gravel or slag cushion, plastic drainage board, plastic blind ditch, gravel blind ditch, sand quilt, sand bag, horizontal drainage ditch, horizontal drainage pipe, etc. One or more drainage methods.

Further, the surface of the horizontal pore pressure dissipation drainage body is also covered with an anti-blocking layer that prevents external debris from entering the horizontal pore pressure dissipation channel and causing blockage. The anti-blocking layer is selected from cover plates, wrapped geotextiles or used for filtering One or more materials such as geotextiles.

The connection mode of the vertical pore pressure dissipating drainage body and the horizontal pore pressure dissipating drainage body is selected from one or a combination of overlapping, binding, and binding.

A ground treatment method for earthquake resistance and disaster reduction of liquefiable ground, characterized in that it comprises the following steps:

Before foundation reinforcement, set up the above-mentioned system as an integral part of foundation reinforcement measures during construction;

carry out ground reinforcement treatment;

After the foundation reinforcement is completed, the system is retained as a permanent channel for the foundation to dissipate the excess pore water pressure generated by the earthquake.

A ground treatment method for anti-seismic and disaster reduction of liquefiable ground, characterized in that the system as described above is installed on the ground that has been strengthened as a channel for dissipating excess pore water pressure when an earthquake occurs during the operation period.

According to the method, a permanent excess pore water pressure dissipating channel is set for the liquefiable foundation, the excess static pore water pressure is controlled and reduced, and the source of liquefaction is prevented, thereby improving the anti-seismic liquefaction performance of the foundation. The dissipating channel can be arranged before the foundation reinforcement, as a drainage system for foundation treatment during the construction period, and as a permanent ultra-static pore water pressure dissipating channel after the construction period is completed. It can also be arranged after the foundation is strengthened as a permanent facility during the operation period.

Description of drawings

Fig. 1 is a schematic diagram of an earthquake resistance and disaster reduction system for liquefiable foundations.

Among them, liquefiable foundation 1 vertical pore pressure dissipation drainage body 2 horizontal pore pressure dissipation drainage body 3 surface drainage system 4

Specific implementation method

Example 1

This example is an embodiment of installing an earthquake resistance and disaster reduction system in a liquefiable foundation that has been reinforced.

1. As shown in Figure 1, it is the liquefiable foundation 1 that has been reinforced. A vertical pore pressure dissipating drainage body 2 is inserted in the foundation. The vertical pore pressure dissipating drainage body is selected from one or more drainage materials selected from water collection wells, tube wells, vertical plastic drainage boards, cardboards, sand piles, bagged sand wells, and sandstone piles. The vertical pore pressure dissipating drainage body 2 must penetrate through the silt, muddy soil or clay layer that may exist on the surface, and reach the sandy soil or silt layer in the liquefiable foundation.

The insertion spacing and depth of the vertical pore pressure dissipating drainage body 2 are calculated according to geological conditions, earthquake resistance level or structural characteristics of buildings.

2. Lay a horizontal pore pressure dissipating drainage body 3 on the surface of the liquefiable foundation 1, cover the cover plate, outsource the geotextile or filter layer, prevent other sundries from entering the channel, and maintain the patency of its drainage. Wherein, the horizontal pore pressure dissipation drainage body is selected from sand, gravel or slag cushion, plastic drainage board, plastic blind ditch, gravel blind ditch, sand quilt, sand bag, horizontal drainage ditch, horizontal drainage pipe, etc. Or more than one drainage method.

The horizontal pore pressure dissipative drainage body is laid on the stable layer of foundation settlement, or the sand or silt layer in the liquefiable foundation 1, and the depth of the buried sand or silt layer is required to be at least 50 cm to prevent the foundation from forming The displacement destroys the horizontal pore pressure dissipation drainage body. According to the water flow and drainage characteristics of the vertical pore pressure dissipation drainage body 2, the spacing and drainage parameters of the horizontal pore pressure dissipation drainage body are calculated.

3. Connect the vertical pore pressure dissipating drainage body 2 with the horizontal pore pressure dissipating drainage body 3, and the connection method can be one or more of them mixed using such as overlapping, binding, and binding.

4. Surface drainage system 4 is uniformly designed for municipal roads. The horizontal pore pressure dissipating drainage body 3 is connected with the surface drainage system 4 to form a pore pressure dissipating channel in a three-dimensional space. The connection method can be one or more methods such as binding, reserved pipe lap, connecting pipe, etc., so that the excess pore water pressure generated by the earthquake can be discharged smoothly and quickly.

Example 2

This example is an embodiment in which an anti-seismic disaster reduction system is installed in a liquefiable foundation before foundation reinforcement treatment.

Before the foundation is strengthened, the earthquake resistance and disaster reduction system of the liquefiable foundation of the present invention is installed, and the installation steps are as described in each step of the embodiment, and will not be repeated here. The installed earthquake resistance and disaster reduction system is a part of the foundation reinforcement measures during construction and is a permanent structure.

Ground reinforcement shall be carried out according to the actual situation.

After the foundation reinforcement is completed, the earthquake-resistant and disaster-mitigation system is reserved as a permanent channel for the foundation to dissipate the excess pore water pressure generated by the earthquake.

Claims (9)

1. An anti-seismic and disaster reduction system for liquefiable foundations is characterized in that permanent vertical pore pressure dissipation drainage bodies and horizontal pore pressure dissipation drainage bodies are set in liquefiable foundations, and the vertical pore pressure dissipation drainage bodies and horizontal pore pressure The dissipative drainage body communicates and connects with the surface drainage system. 2. The earthquake resistance and disaster mitigation system for liquefiable foundations according to claim 1, characterized in that: the vertical pore pressure dissipation drainage body penetrates to reach the sand or silt layer of the liquefiable foundation. 3. The earthquake resistance and disaster reduction system for liquefiable foundation according to claim 1, characterized in that: the horizontal pore pressure dissipation drainage body is laid on the stable layer of foundation settlement, or laid on the sand or silt layer of liquefiable foundation . 4. The earthquake resistance and disaster reduction system for liquefiable foundations according to claim 1, characterized in that: the vertical pore pressure dissipation drainage body is selected from water collection wells, tube wells, vertical plastic drainage boards, cardboard, sand piles, bagged One or more drainage materials in sand wells and gravel piles. 5. The earthquake-resistant and disaster-mitigation system for liquefiable foundations according to claim 1, characterized in that: the horizontal pore pressure dissipation drainage body is selected from sand, crushed stone or slag cushion, plastic drainage board, plastic blind ditch, gravel One or more drainage methods such as blind ditch, sand quilt, sand bag, horizontal drainage ditch, horizontal drainage pipe, etc. 6. The earthquake resistance and disaster reduction system for liquefiable foundations according to claim 1, characterized in that: the surface of the horizontal pore pressure dissipation drainage body is also covered with an anti-blocking layer to prevent external debris from entering the horizontal pore pressure dissipation channel and causing blockage , the anti-blocking layer is selected from one or more materials such as cover plate, wrapped geotextile or geotextile used for filtering. 7. The earthquake resistance and disaster reduction system for liquefiable foundation according to claim 1, characterized in that: the connection mode of the vertical pore pressure dissipating drainage body and the horizontal pore pressure dissipating drainage body is selected from lap joint, binding, and binding One or a combination of several methods. 8. A ground treatment method for earthquake resistance and disaster reduction of liquefiable ground, characterized in that it comprises the following steps: Before foundation reinforcement, the system described in any one of claims 1 to 7 is set as an integral part of foundation reinforcement measures during construction; carry out ground reinforcement treatment; After the foundation reinforcement is completed, the system is retained as a permanent channel for the foundation to dissipate the excess pore water pressure generated by the earthquake. 9. A ground treatment method for earthquake resistance and disaster reduction of a liquefiable ground, characterized in that: the ground that has been reinforced is provided with a system as described in any one of claims 1 to 7 as the dissipation of excess pore water pressure when an earthquake occurs during the operation period aisle.

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