EP1834047A1

EP1834047A1 - Full displacement technique for soil improvement and constructing walls and piles

Info

Publication number: EP1834047A1
Application number: EP04762964A
Authority: EP
Inventors: Osama Kamal Roshdy
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-09-07
Filing date: 2004-09-07
Publication date: 2007-09-19
Also published as: WO2006027000A1

Abstract

A new full displacement technique capable of improving the soil properties to resist different loads, cutoff seepage, and construct piles and flexible walls. The constructed works integrate with the improved surrounding soil in resisting lateral and vertical loads. All the soil improvement systems are performed using single machine having a special driving vibrator and different compaction and pouring casings and applying an innovative construction technique. This patent constitutes practical solution for problems of soft soils.

Description

FULL DISPLACEMENT TECHNIQUE FOR SOIL IMPROVEMENT AND CONSTRUCTING

WALLS AND PILES

Technical Field

The invention relates to soil improvement by constructing full displacement continuous walls and/or piles in soft saturated soils. Special casings are used to construct the walls and the piles allowing for controlling the soil displacement and improvement direction. In addition, these casings could be used in forming and compacting new soil layer at the desired depth allowing for forming a bearing layer for walls and piles and eliminating the need to reach the natural end bearing layers which could exist at larger depths. The invention also related to reducing the soil resistance to allow for penetrating dense sand layers by jetting bentonite slurry.

Background Art

The background art is represented by patent application no. 1 1 1/2000 submitted on

31/12/2000 to the Egyptian Patent Office by Osama K. Roshdy, inventor of the current patent application. This patent application is related to constructing deep continuous strengthening wall capable of cutting seepage off, resisting lateral loads, and improving the surrounding soil properties using the full displacement technique. In addition, the wall could be deep or shallow, thin or thick, with or without piles used for strengthening the entire wall system. Two additional features could be added depending on the soil condition, vertical sand drains to accelerate the consolidation of soft soil layers and allow for dissipating the pore water pressure generated as a result of using full displacement technique in constructing the wall. One more feature which could be added is preboring of the piles or the wall portions before constructing them, this allows for the gradual application of displacing and compacting the soil and leading to lower pore water pressure generation. The background art could be summarized as follows:

1 - The prior art has been restricted to using the full displacement technique in constructing single piles or closed ended pipes penetrating the soil by driving. The spacing between centers of the driven piles should not be less than two and half times the pile diameter. The prior art also contains construction of piles by driving them into the soil using vibratory drivers to specified depths, but the prior art did not contain any practical method using full displacement to construct deep, continuous, and flexible walls capable of cutting seepage off and resisting different types of loads.

2- In 1989, Verstraeten presented a construction technique for constructing thin slurry walls in US patent no. 4,887,357 using the driven beam method. 3- On 31/01/2000 patent application No. I l l for the year 2000 (111/2000) has been filed in the Egyptian Patent Office by the inventor (Osama Kamal El-Sayed Roshdy) under the name: New Technique to Construct an Impervious Continuous Stabilizing Wall Using Full Displacement. This technique could construct continuous stabilizing walls and single piles using full displacement by using special pouring and compaction casings and special vibratory drivers and also special construction technique, as shown in Figures 1 through 7.

The background art has the following shortcomings as follows: 1 - The inability to construct continuous walls.

2- Tilting in the previously driven piles when driving the next piles (using driving technique) due to the large displacements that take place in the soil with each blow.

3- For US patent no. 4,887,357 the method applicability is restricted to constructing thin and shallow walls. In addition, the driven beam forming the wall has a constant cross-section allover the beam length requiring great driving and extraction energies, and consequently, limiting the thickness and depth of the wall. Moreover, the used beam is not equipped with lost shoe restricting the ability to pour concrete and the inability of the method to place steel reinforcement cages.

4- For patent application No. 111/2000 registered in the Egyptian Patent Office, it has ^; the following shortcomings: a. The limited depth and pile diameter which could be constructed due to the increased soil resistance under the pile tip and around the pile surface during the driving operation. This is accompanied by an even harder casing extraction process. b. The possibility of stoppage of the pouring and compaction casing inside the sand lenses due to its high resistance to penetration (just below the casing tip) due to the increased soil compaction underneath it. c. An increased volume that takes place in the soil due to extraction of the used driving casing due to sticking of some compacted soil with the casing surface. This leads to an increased volume of the required filler material and consequently an increased cost. d. Improving the mechanical soil properties for resisting lateral loads only, with no improvement for the mechanical soil properties in the vertical direction. e. The inability to penetrate sandy soil lenses of large thickness due to the inability of displacing the soil preventing penetration of the driving casings. f. The limited ability of the piles and walls constructed using this technique in resisting vertical loads. g. The inability of this technique to prevent chemical ground water attack on piles and walls in soft soils, therefore reducing the proposed age of the project. h. A considerable portion of the construction time is lost in cleaning the outer surface of the pouring and driving casings to remove the compacted soil sticking on the casing surface during the extraction process.

Disclosure of the Invention

The entire disclosure of Egyptian Patent Application No. 111/2000 filed on January 31, 2000 and Egyptian Patent Application No. 369/2004 filed on August 26, 2004 including specifications, claims, drawings, and summary are incorporated herein by reference in its entirety.

The patent idea depends mainly upon compacting the soft soils to improve its properties and determines the compaction direction to counteract the required load direction at the required depth using full displacement. The technique is applied using innovative compaction and pouring casings capable of easily penetrating different soil layers due to equipping these casings with lubrication and soil displacement systems for displacing the sandy soil lenses allowing for penetration of these lenses. This allows for large reductions in soil resistance during the casing pushing process inside the soil whereas the casing pushing and extraction is performed using low frequency vibrators and high dynamic forces which could push the casing into the soil. and extract it without causing resonance in the different soil layers during construction. Therefore, allowing for constructing structures on weak soil layers without the need to reach dense sand layers which could be encountered at large depths. This allows for reducing the overall cost of the construction projects in such cases with high construction rates and speedy achievement of the targeted results.

According to the present invention, there provided a new full displacement technique for improving soil properties, constructing piles and continuous walls, reducing the soil resistance at the required depths, and forming densely compacted layers at the specified depths, comprising:

1 Pre-boring and compaction casing for piles having circular cross-section to apply the soil compaction gradually, along with pouring filler materials without reinforcement steel cages.

2 Universal driving machine used for driving all the used casings.

3 Universal driving vibratory hammer.

4 Innovative compaction and pouring casing of rectangular cross-section.

5 Pouring and compaction casing for constructing piles of circular cross-section using lost shoe. 6 Continuous stabilizing and/or cutoff wall constructed in parts Pl, P2, P3, etc. with overlapping distance 6-1, with plan view of the wall shown in Figure 6 and vertical cross-section of the wall, during construction, shown in Figure 5.

7 Concrete piles.

8 Vertical sand drains

9 Zone of improved soil properties.

10 Lateral loads imposed on the wall and pile stabilizing system.

11 Highway embankment or any vertical loads.

12 Pouring and compaction casing with capability of bentonite slurry jetting to be able to penetrate sandy soils lenses.

13 Pouring and compaction casing with capability of bentonite slurry jetting and pouring filler materials like concrete and bentonite slurry producing continuous wall of rectangular cross-section.

14 Formed soil plug at any specified depth to support end bearing piles or walls, therefore resisting vertical loads.

15 Impermeable soil layer.

16 Seepage cutoff wall .

17 Seepage line.

18 Waterway.

19 Dense soil layer penetrated using the innovative special penetration casing.

20 Slope to be stabilized and/or strengthened.

21 End bearing dense sand layer.

22 Soft or weak soil which needs improvement or stabilization.

The construction sequence along with uses and advantages of the new technique is presented as follows:

1- Vertical sand drains (8) are constructed first to accelerate the soil consolidation process and dissipate the excess pore water pressure generated during construction of other soil improvement and stabilization process using full displacement technique.

2- The innovative compaction and pouring casings (1), (4), (5), (12), and (13) devised in this patent, are shown in Figures (1, 2, 3, 4, 8, 9, and 10). These casings are used to perform any of the following tasks; perform pre-boring, pour filler materials like bentonite slurry and concrete, pour filler materials like concrete and allowing for placing steel reinforcement cages, all according to the required task. Therefore, according to the needed structure, the designated casing is used to construct piles (7) or continuous bentonite or concrete walls (6) using full displacement and improve the soil properties in the required direction and up to the required improvement degree. - When reduction in soil resistance is required to penetrate dense soil lenses at certain depths, a special casing (12) is used. In addition to overcoming the soil resistance, larger depths could be reached due to displacing the sandy soil lenses (19) in front of the frontal portion (12-1) of the casing to allow for continuous advancement of the casing inside the sandy layers. Penetrating these sandy layers (19) allows for the possibility of reaching deeper layers which could not be reached using any of the prior art techniques, as shown in Figure 13. - When an end bearing soil plug (14) is required to be formed at any depth, casings (5) or (12) are used to add the required filler material at the designated depth. This filler material could be either sand or gravel or mix of both or any other suitable material. The resistance of the soil around the casing is reduced by jetting bentonite during the casing driving process allowing for the dynamic forces generated from the driving vibrator (3) to compact the added filler material (soil replacement) till reaching the driving stoppage. - The method presented in this patent is capable of improving the soil properties around and under the constructed works, allowing for integration of that improved soil with the constructed works in resisting different loads, horizontal (10) and vertical (11) and cut seepage (17) off, achieving all the results with the lowest possible cost and the highest possible construction rates. - The patent could be used in producing different systems capable of cutting seepage (17) off, cutting seepage (17) off and resisting horizontal loads (10), and cutting seepage (17) off and resisting both vertical (11) and horizontal loads (12) at the same time, as shown in Figures 12 through 15. - The final product of the integrated soil improvement systems could be used in stabilizing slopes (20), improving the soft soil (22) properties, reaching deeper dense soil layer (21), penetrating dense soil layers at shallow depths (19), forming bearing soil plugs (14) at the desired depth all using single driving machine (2), single vibratory driving hammer (3), and a group of innovative pouring and compacting casings (1, 4, 5, 12, 13). - When reduction in the soil resistance is required, bentonite slurry is jetted around the driving case, during the driving process (explained in Figures 9 and 10), make a thin lubrication film around the driving casing separating the casing and the surrounding compacted soil. This allows for reducing the soil resistance during driving the casing into the soil, therefore, greater depths could be reached with large saving in the energy consumed, and assuring homogeneity of the soil resistance around the casing body. In addition, this condition prevents the casing from deviating away from the required vertical direction inside the soil. Reducing the soil resistance around the casing body allows for applying the vibratory hammer (3) dynamic energy in compacting the soil in the vertical direction and for controlling the condition at which the driving stoppage state is achieved. This assures reaching the soil resistance to vertical loads (11) to a predetermined value which could be easily noticed when the vertical movement of the casing stops after the soil reached the driving stoppage condition.

9- Flexibility of application and constructing only the works sufficient to achieve the targeted results with the lowest cost. The required degree of improvement in the soft soil (22) properties could be controlled by controlling the amount of applied compaction displacement. Also, the displacement direction could be directed according to the required results which to be achieved at the lowest cost. Figures 12 through 15 represent integrated systems to achieve different results with the lowest cost.

Practical Applications of the Invention

The invention can be used in a wide range of application including the following fields:

1- This patent could be applied in constructing harbor decks in areas of soft and weak soils with low cost and high construction rates.

2- The patent could be applied in constructing airport runways, highways, electricity generation plants, water purification plants, sewage treatment plants, pumping stations for drains and canals, in soft soils with low costs and high construction rates.

3- The patent could be used in soil stabilization on the sides and underneath water structures and different foundations (bridges, barrages, pumping stations, dams, etc.) with low costs and high construction rates.

4- Protection of archeological areas and sites of high historic value from rising of the ground water table, cutting seepage off, and stabilizing the surrounding soils with the lowest possible cost and the highest possible construction rates.

5- Constructing deep foundations for different structures with high safety to assure the safety of the surrounding structures with the lowest possible cost and the highest possible construction rates (e.g., underground garages, offshore structures, and structures in rivers, etc.).

6- Cutting seepage off for water canals and drains if high permeability soils exist in the waterway sides. The included figures show the following:

1- Figure 1: shows the preliminary boring casing (1), and compaction and pouring casings (4 and

5) as presented in patent application No. 1 11/2000 (prior art), along with the used vibratory driving hammer (3) and driving machine (2). The figure shows the coincidence of the vertical axis of the casing (4) and the vibratory hammer (3) and the vertically of the casing vertical motion is also assured through the guidance unit affixed on the machine (2-1) in Figure 1. Whereas, the verticality of the sliding vertical motion of the vibratory hammer (3) on the machine head (2-3) is assured through coinciding the vertical axis of the machine (2) with that of the casing (4) through the guidance unit relative to the machine head (3-1) in Figure 1.

2- Figure 2: shows the frontal part of the casing penetrating the soil, Part (1-1) has a solid conical shape and affixed to the casing body (1-2). Whereas, the upper end of the casing (1-3) has a special shape allowing for easy guidance and fixing in the vibratory hammer (3) during the driving and extraction process, always coinciding with the casing axis. Both axis coincide with the vibratory hammer (3) axis to assure eliminating any non-vertical components for the dynamic forces generated by the driving vibrator (3) during driving the casings into the soil and extracting them from the soil.

3- Figure 3: shows the compaction and pouring casing (4) used in constructing piles and walls with rectangular cross-section, capable of directing the soil displacement to be perpendicular to the one axis of the casing, as presented in patent application No. 111/2000 (prior art). This frontal portion (4-2) of the pouring and compaction casing is connected with the lost shoe, Part (4-1), having a shape controlling the displacement direction during driving the casing into the soil and also designed to be water-tight preventing ground water from entry into the casing interior during the driving and extraction process. The design also assures the ease of detachment of the lost shoe (4-1) from the driving casing (4) and leaving it in the ground under the filler material after extraction of the driving casing from the soil by the driving vibrator (3).

4- Figure 4: shows the casing (5) used in compaction and pouring, used in constructing piles with circular cross-section as presented in patent application No. 111/2000 (prior art). The drawing indicates that the frontal portion (5-2) of the casing, which penetrates the soil, has a conical shape which could be detached from the casing body (5-2). This conical part (5-1) could be precisely and easily attached to the casing assuring coincidence of the vertical axis of both the cone (5-1) and the casing (5-2). Moreover, the connection between the casing and the cone is designed to be water tight preventing the ground water from entry into the casing. After completing the casing driving process, the filler material could be poured inside the casing and when extracting the casing upwardly using the vibratory hammer (3), the conical shaped lost shoe (5-1) is left in the soil due to the weight of the filler material over it. Therefore, the casing (5-2) and (5-3) without the lose shoe are extracted from the soil. The casing used in this condition is called the casing with lost shoe. - Figure 5: This drawing shows the construction of deep continuous bentonite wall (6) using the innovative technique presented in patent application No. 111/2000 (prior art). This is performed by the compaction and pouring casing of rectangular cross-section (4) and lost shoe (4-1) with frontal portion (4-2) capable of penetrating and soil and directing the soil displacement to be perpendicular to the wall axis. The technique also assures the wall continuity without enclosing any natural soils between the interfering wall portions and also to compress and displace the soil in the wall perpendicular direction. This compaction assures enhancing the soil properties surrounding the wall (6) and increases its lateral load carrying capacity exerted on the wall, whereas cutting the seepage off take place by the bentonite mix forming the wall body. Parts Pl, P3, P5, etc. are performed first, then the remaining parts P2, P4, P6, etc. are performed afterwards all with an overlapping distance, (6- 1 ), allowing for constructing a continuous wall (6). - Figure 6: shows elements of the technique used to construct a deep cutoff and stabilizing wall performed using full displacement technique. This wall is a product of the patent application No. 111/2000 (prior art), which shows stages of constructing a single portion (for example Pl, P2 etc.) of the wall, as part of the continuous wall, (6). - Figure 7: shows the shape of one of the integrated cutoff and soil improvement systems, capable of resisting the soil lateral movements (due to the loads exerted on it (10 and H)). This is considered one of the products presented in the patent application No. 1 1 1/2000 (prior art). The figure shows sand drains (8) performed using full displacement and continuous cutoff and stabilizing wall (6) which improves and compacts soils along the wall sides. Reinforced concrete piles (7) of circular cross-section with depth more than the depth of the wall used to stabilize the wall (6) and increase its lateral load carrying capacity. This construction technique is used to improve the soil properties and assure its integration with the constructed works in cutting off seepage and resisting lateral loads (10) only. The figures also shows the zone of compacted and improved soil properties (9) constructed inside soft soil (22). - Figure 8: shows the driving machine (2), the vibratory driving hammer (3) and the innovative pouring and compaction casings (5, 12, and 13). - Figure (9): shows the innovative cylindrical casing (12) that could be used to compact the soil laterally around the casing and vertically under the casing tip and also for preliminary boring and pouring the filler materials which do not include steel reinforcement bars. The casing is also equipped with a bentonite slurry pumping system (nozzles A and B) around the casing body (12-2), nozzles (A), operated during the driving process inside the soil. Other nozzles (B) in front of the casing (12-1) to reduce the soil resistance during penetrating the sand lenses. The casing could also be filled with filler material (mix of gravel and sand or one of them or bentonite mix or any other filler material not containing steel reinforcement cage). These filler materials are poured inside the casing during the casing extraction process. The casing could also be used in compacting the soil vertically at a specified depth or adding any additional soil to it (like gravel-sand mix or one of them) forming a plug (14) and compacting it inside the soft soil (22). Thus, the properties of large areas of the soil under the casing tip (12-1) and around it are improved. Therefore, compacted soil with improved properties (14) are formed under the casing tip (12-1) and around it making it capable of resisting both lateral (10) and vertical loads (11) at the same time. 0- Figure 10: shows an elevation and side view of the innovative casing with rectangular cross- section (13) that could be used in constructing walls and/or piles with rectangular cross- section (without steel reinforcement cages) capable of compacting the soil under and around it in both the lateral and vertical direction and improve its properties. Nozzles (A) and (B) are used to pressurize bentonite slurry into the soil during the driving process allowing for forming a thin film of bentonite slurry around the casing and thus reducing the soil resistance to driving and eliminating the effect of negative skin friction of soft and weak soils on the wall and/or pile surface. 1- Figure 11: shows drawing for the innovative construction technique to construct piles (7) and/or walls (6) with the innovative casing to compact the soil vertically and laterally and filling with the filler materials not including steel reinforcement. The formed soil plug (14) formed in the soft soil (22) under the casing tip is a newly formed end bearing layer, formed at the required depth. 2- Figure 12: shows a thin seepage cutoff wall (16) constructed inside the high permeability soil with the casing (13) shown Figure 10. The wall(s) are constructed to cut seepage (17) from any waterway (18) down to an impervious soil layer (15). The safety of the slopes (20) could be increased as a result of constructing such walls using full displacement technique. 3- Figure 13: shows two parallel bentonite walls (16) for seepage cutoff and improving the soil

(22) between the walls and around them to be able to resist lateral loads (10), stabilize slopes (20), and prevent seepage, without using and reinforced concrete piles. Applying the innovative technique, dense sand lenses (19) could be penetrated down to the any depth, other sand layer (21) for example. Sand drains (8) could be used to further improve the soil properties. - Figure 14: shows a deep flexible wall (6 or 16) stabilized by a group of reinforced concrete piles (7), and capable of cutting seepage off (16) and resist both vertical (11) and lateral loads (10), improve the soil properties (9), stabilize slopes (20). In addition, a soil plug (14) could be formed at the required depth to resist vertical loads. - Figure 15: shows a system comprising two flexible parallel walls (6) stabilized with groups of reinforced concrete piles (7). This system is capable of cutting off seepage (17) and resisting lateral (10) and vertical (11) loads, and stabilize slopes (20) at the same time. The system could be used to construct dams, foundation bridges, barrages, airport runways, foundations of water structures and power stations. The system could also be used in constructing offshore protection structures, etc.

Claims

CLAIMS - A new full displacement technique for improving the soft soil properties to resist both horizontal and/or vertical loads, construct continuous walls, block seepage, stabilize slopes, overcome soil penetration resistance at certain depths, all using a single machine and a group of pouring and compaction casings applying an innovative construction technique, as shown in Figures 1, 5, 8, 13, and 15. - The pouring and compaction casings as presented in Claim (1), as shown in Figures 2, 3, 4, 9, and 10 are characterized by having special innovative shape allowing for constructing continuous walls using the casing of rectangular cross-section, circular piles using the casing of circular cross-section, perform pre-boring to increase the soil compaction gradually, and the ability of the casing to direct the soil displacement in the desired direction and consequently the soil improvement direction. - The pouring and compaction casings as presented in Claim (1) are characterized by the ability to pour different types of filler materials like concrete, bentonite slurry, and plastic concrete constructing different types of walls and piles, hi addition, the casings can pour concrete and place steel reinforcement cages. - The pouring and compaction casings as presented in Claim (1) are characterized by the ability to reduce the soil resistance by jetting bentonite slurry allowing for penetrating the dense layers at any depths till reaching the required bearing depth. The jetted bentonite slurry forms a thin film between the casing and the surrounding soil reducing the soil resistance in hardly penetrated soils and on the other hand, eliminating the negative skin friction in soft and very soft soils. - The pouring and compaction casings as presented in Claim (1) are characterized by the ability to construct continuous walls without enclosing any natural soils between parts performed by the casing of rectangular cross-section by overlapping portions of the continuous walls. - The innovative construction technique as presented in Claim (1) are characterized by performing sand drains before constructing the soil improvement system to allow for accelerating the soil consolidation process and dissipate the increase in the pore water pressure that takes place during construction using full displacement technique. - The single machine as presented in Claim (1) is characterized by special design of the machine and vibratory hammer to drive different types of casings, having different shapes, heights, and weights. The special design also includes using frequencies that do not cause resonance in the soil during the driving operation.