The present invention relates to a system and method for surcharging the soil for ground improvement works.

Background of the Invention

Conventional methods for surcharging use earth filling in order to accelerate the consolidation of the subsoil. The height of the of the earth filling surcharge is dependent on the requirement of the surcharge load.

There are disadvantages with the conventional surcharging methods, such as, the suitability of backfill soil may not be available on site and need to be imported. For areas which is scarce of earth, importation of earth for surcharging can be costly and time consuming. The backfilled earth normally need to be compacted for adequate density and safe stability. The compaction of backfill soil consumes time and is difficult during the raining season. The removal of the surcharge soil can be time consuming and costly if the disposal site is far from the working site.

Summary of the Invention

The present invention relates to a method of using liquid as a surcharge load instead of earth. A retaining structure is constructed at the perimeter of a surcharging zone. A surcharging platform is constructed and may be leveled, and sharp materials removed. An impermeable membrane may be laid on the surcharging platform and the retaining structure for the liquid surcharge load. Liquid piping and drainage system may be designed accordingly for loading of liquid and discharging of liquid during unloading or contingency. Trigger sensors may be installed to ensure consistent height of liquid surcharge to ensure consistent loading. Instrumentation monitoring especially settlement gauges may be installed to monitor the rate of consolidation.

Preferably, the location, size and perimeter of a surcharging area is identified and marked accordingly. Preferably, an impermeable membrane may be designed to ease the transportation and laying work.

Preferably, the thickness of the impermeable membrane may be specified according to the requirement of the project.

Preferably, the upper layer of soil may be leveled to construct a working platform, and sharp materials removed, which may puncture the impermeable membrane. After constructing the working platform, a retaining wall, or equivalent may be constructed at the perimeter of the surcharge cell to retain the liquid surcharge. The retaining wall may be an earth berm, concrete, sheet pile, reinforced wall.

Preferably, the retaining wall, may be constructed in sections. The main objective is for contingency purposes, where in case of wall, failure, the total volume of liquid discharged is limited to prevent untoward incidents.

Preferably, the retaining wall, may be designed according to the height of the liquid surcharge and subsoil conditions and requirements. As necessary, drainage system may be designed and installed.

Preferably, the impermeable membrane may be a single sheet or a plurality of sheets. It may be laid according to a required design configuration and the joining of the impermeable membrane, if required, by sealing means, such as, overlapping, welding, or adhesive may be done on site or off site to prevent any leakage. The impermeable membrane may be laid to cover the surcharge area, that is, the working platform and the inner surface of the retaining wall.

Preferably, liquid may be pumped or poured into the surcharge area to the required height.

Preferably, a trigger sensor may be installed at a level of the liquid surcharge which is higher or lower than the required liquid level to indicate the minimum static surcharge load. If the liquid level drops below the trigger level, additional liquid may be pumped in to maintain the minimum liquid level.

Preferably, after the completion of the surcharging period or the settlement rate of the ground has achieved satisfactory, the surcharge liquid may be drained according to the designed flow.

The present invention consists of certain novel features and a combination of parts hereinafter fully described and illustrated in the accompanying drawings and particularly pointed out in the appended claims; it being understood that various changes in the details may be ossible without departing from the scope of the invention or sacrificing any of the advantages f the present invention.

Brief Description of Drawings

In the following drawings, same reference numbers generally refer to the same parts throughout. The drawings are not necessarily to scale, instead emphasis is places upon illustrating the principles of the invention. The various embodiments and advantages of the present invention will be more fully understood when considered with respect to the following detailed description, appended claims and accompanying drawings wherein:

Figure 1 : illustrates the cross-sectional view of the surcharge cell describing the features of the surcharge cell.

Figure 1A: illustrates the surcharge cell with embodiments for maintaining the surcharge load.

Figure IB: illustrates the arrangement of the sections of the retaining wall of the surcharge cell.

Figure 2: illustrates the the top view the surcharge cell with an illustrative configuration of the impermeable membrane layout. Detailed Description of the Invention

The present invention relates to a method of surcharging the ground to accelerate the consolidation of soil for site improvement. Among the objective of the method is to dissipate liquid that may be trapped in the earth by placing a load on the site to be worked on. Thus improving the earth and strengthening it.

As an improvement over conventional methods of using earth as a surcharge medium,the present invention uses liquid instead of earth as the surcharge load. Liquid is easily obtainable on site, such as, from rivers, streams, drains, groundwater, and tap water, compared to backfill soil. Liquid does not require compaction as compared to backfill soil. Liquid has a consistent weight, and this consistency is advantageous over earth in ensuring consistent surcharge loading. Discharging water is easier as compared to disposing backfill soil. The maintenance of a consistent surcharge load is easier by maintaining the height of water surcharge as compared to leveling of backfill soil which is subject to differential settlement. The consistency of weight is advantageous over earth in ensuring a consistent surcharge loading.

Refering to Figure 1 , performing the method, the location, size and perimeter of a surcharging area is identified and marked accordingly to the terrain of the location. The dimensions of the load cell is determined accordingly. The volume of liquid (5) to be deployed as the surcharge load is derived from the target load requirements.

To prevent liquid from leaking into the earth an impermeable membrane (2) may be used and designed to ease the transportation and preparation works for the filling of the load cell.

The thickness of the impermeable membrane (2) may be derived according to the requirements of the project.

The upper layer of soil may be leveled to construct a working platform (3), and sharp materials removed, which may puncture the impermeable membrane (2). After constructing the working platform (3) and impermeable membrane (2) a retaining wall (1) or equivalent may be constructed at the perimeter of the load cell to retain the liquid surcharge (5). The retaining wall may be an earth berm, concrete, sheet pile, reinforced wall.

Refering to Figure 1A, to monitor and measure the liquid quantity stored in the load cell, variation of methods may be employed. Digital means may be employed using sensors to measure and monitor the depth of the liquid (5) in the load cell. Analogue means may be employed using a form of measure, such as a rule, to monitor and measure the depth of the liquid (5) in the load cell. Alternatively, pressure exerted by the load may be monitored and measured. These are possible means of monitoring and measuring the load. A load indicator may be used to visually check the loading.

Referring to Figure IB, the retaining wall (1) may be constructed in sections (la). The main objective is for contingency purposes, where in case of retaining wall failure, the total volume of liquid discharged is limited to prevent untoward incidents.

The retaining wall (1) may be designed according to the height of the liquid surcharge (5) and subsoil conditions and requirements. As necessary, piping and drainage system may be designed and installed.

Refering to Figure 2, the impermeable membrane (2) may be a single sheet or a plurality of sheets. It may be laid according to a required design configuration and joining of the impermeable membrane (2), if required, by sealing means, such as, overlapping, welding, or adhesive may be done on site or off site to prevent any leakage. The impermeable membrane (2) may be laid to cover the surcharge area, that is, the working platform (3) and the inner surface of the retaining wall (1).

When the ground is prepared the, load liquid (5) may be pumped into the load cell to the required volume.

A trigger sensor (6) may be installed at a level of the liquid surcharge which is higher or lower than the required liquid level to indicate the required static surcharge load. If the liquid level drops below the required level, additional liquid may be pumped in to maintain the required liquid level.

Upon the completion of the surcharging period or the settlement rate of the site has achieved satisfactory, the load liquid (5) may be drained out via an outlet (4) according to the designed flow.

For safety, a barb wire fence may be installed surrounding the surcharge area to prohibit irrelevant person from entering. Signboards may be installed to warn people from entering the surcharge area.

While the foregoing description presents preferred embodiments of the present invention along with many details set forth for purpose of illustration, it will be understood by those skilled in the art that many variations or modifications in details of design, construction and operation may be made without departing from the present invention as defined in the claims.