BR202014027481Y1 - soft and very soft soil sampler with cable-operated jaw device and with soil flow between the jaws and the sampling tube - Google Patents

Abstract

ï »¿summary soft ground sampler construction arrangement as described in the report and according to the accompanying drawings refers to the present utility model patent application to a soft ground sampler construction arrangement . More specifically, a sampler equipped with a mechanism called cut-holder, shaped like a spherical hubcap, with jaws connected like jaws, which aims at the end of the crimping to cut the sample so as not to Push it into the sampler, as well as prevent it from slipping, thus ensuring its recovery with minimization of dimming effects.

Description

“SAMPLER FOR SOIL AND VERY MOLES WITH JAWS DEVICE, ACTIVATED BY CABLES, AND WITH SOIL FLOW BETWEEN THE JAWS AND THE SAMPLE TUBE”

SUBJECT MATTER

The present utility model patent application refers to a constructive arrangement for collectors of superficial and deep samples of soft and very soft soils. More specifically, a sampler equipped with a mechanism called cut-support, with perfect spherical cap shape, with blades connected as jaws, which aims, at the end of the driving, to cut the sample so as not to push it into the sampler, as well as preventing it from slipping, thus guaranteeing its recovery, minimizing the denting effects, and greater efficiency and yield in the sampling procedure. With this sampler, there is no need for waiting time after driving to extract the sample, as in other samplers, according to the standard of ABNT NBR 9820: 1997. In addition, there is a guarantee of sample recovery, even with very low resistance, since the support is provided by the base of the sampler. A fundamental feature of the cut-support mechanism is that it has a section projected on a very small horizontal plane in the open condition, in order to offer the least possible resistance to driving. The idea was that the soil external to the tube “flowed”, during the driving, between the outer wall of the tube and the cut-off mechanism. If this were not the case, the setting of the sampler would generate denting of the soil to be sampled, below the sampler, during the sampling process.

APPLICATION FIELD

The object of the present utility model patent application belongs to the field of application in geotechnics. The subject is part of the theme of foundations, with soil studies of foundations in situ, these being carried out before construction work, based on soil sampling (IPC E02D 1/04). The subject is also relevant to the field of investigation or analysis of materials by determining their chemical or physical properties, using specific sampling equipment, with solid state samples and a specific extraction tool (IPC G01N1 / 08). The subject

2/15 can also be inserted in other themes, such as ports - which are usually built in regions with extremely soft soils - and works in need of sedimentation studies. Anyway, any area of knowledge - including the environmental one - in which the collection of soft, or very soft, soil samples is necessary may benefit from the sampler.

TECHNICAL STATUS

With the advancement of research in the stress-strain-resistance study of soil properties, the importance of investigating soil structure to define its mechanical behavior, both in terms of strength and deformability, becomes increasingly evident . For this, the collection of undisturbed samples is of fundamental importance. According to Hvorslev (1949), the samples are classified as:

1. non-representative samples - consist of mixtures of materials from layers of soil or rocks, or are samples in which some mineral constituents may have been removed, for example, by washing during the process of water circulation in the percussion drilling. The earthy materials suspended in this circulating water are examples of unrepresentative samples. Such samples do not represent the materials of the subsoil, serving only for a preliminary classification, and determination of depths in which there are variations in the soil profile. They also serve to help program the definition of the depths of representative and undeformed samples;

2. Representative samples - contain all the minerals that make up the layers from which they were taken and have not been contaminated by materials from other layers, but the soil structure has been seriously disturbed (dented) and the moisture content may have been modified. They are used for soil identification and classification, but not for tests where mechanical properties must be obtained. Examples can be culled or helical samples and samples obtained with the SPT standard sampler;

3. undisturbed samples - samples in which the material has been subjected to such minor disturbance that it is suitable for all laboratory tests and determinations of strength, deformability and permeability properties, among others. It is worth remembering that there is always a disturbance associated with the variation in the state of tensions suffered by

3/15 sample during field sampling and after withdrawal. As examples, block samples and those obtained with thin-walled samplers (Shelby type), stationary piston, Denison, Sherbrooke and Lavai, all of which are recognized by international practice, can be mentioned.

Despite the sampler described here being able to obtain undisturbed samples of soft and very soft soils of excellent quality - used to determine the stress-strain-resistance properties of the material in laboratory tests it can also be used in cases where, although there is no need for undisturbed samples, but only representative, these are difficult to sample, in view of the low consistency of the material.

THE SAMPLING PROCESS AND TENNISHING

According to Martins (2011), denting is the partial or total destruction of the soil structure, the structure being understood as the original spatial arrangement or arrangement that the set of grains forming that soil presents in the field. In the case of saturated soft clays, denting is an undrained process and, as such, without volume variation. Thus, denting is the destruction of the soil structure by the distortions imposed on it throughout the whole process of sampling and preparation of the specimen, as listed below, according to Ladd and DeGroot (2003):

1. distortion by extension due to the relief of the total vertical stress by opening the sampling hole;

2. distortion of the soil elements sampled next to the sampler's internal wall during driving;

3. expansion of the soil after driving and before the extraction of the pipe in the soil;

4. tube extraction;

5. transport and storage of samples;

6. extrusion of the sample from the inside of the tube;

7. preparation of the specimen.

The usual Brazilian practice, recommended in ABNT NBR 9820: 1997, is to use internal clearance, the main purpose of which is to reduce the shear stresses between the sample and the sampler internal wall during the driving process. In this condition, immediately after driving, and above all without

4/15 the use of a piston, there would not be enough shear resistance on the walls to support the weight of the sample. The sample then expands laterally until it meets the sampler wall, a process during which some drainage occurs. This is the main reason why a waiting time is necessary (Martins, 2011) before extracting the sampling tube with the collected soil sample. Even in the case of sampling tubes without internal clearance there is a need for a waiting time, which occurs even in the case of stationary piston samplers.

Ladd and DeGroot (2003) mention that, during the extraction of the tube with the sample, the clay under the base of the tube resists the removal of the sampling tube, due to its own resistance and the suction created in the void left by the tube with the sample . In addition, the pore pressure in the clay reduces as the pipe is brought to the surface, which can lead to the formation of gas bubbles due to the dissolution of the dissolved gas (e.g. Hight and Leroueil, 2003).

It appears that denting generates changes in several geotechnical parameters of the sample collected, which is discussed in many articles, for example Lunne et al. (1997) and Leroueil and Hight (2003). The most striking effects of denting on the sample, with regard to densification tests, reported by Ladd (1973), Martins (1983), Martins and Lacerda (1994) are:

1. whatever the effective vertical tension, the void index is always lower for the lower quality sample;

2. the section with the greatest curvature, in the graph between the voids index by the effective vertical tension, becomes less accentuated, making it difficult to determine the oversensing tension;

3. reduction of the estimated value of the oversensing voltage;

4. increased compressibility in the recompression section, causing an increase in the recompression index;

5. decrease in compressibility in the virgin compression section, causing a decrease in the compression index.

In the case of other laboratory tests, denting also causes changes in the mechanical properties of soils. For example, in the case of triaxial compression tests (CAU), densified anisotropically for field stresses, better quality samples provide higher shear strength values and lower deformations to achieve maximum shear stresses (Lunne et al ., 1997).

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Thus, the limitations associated with the sample recovery process after driving are (Martins, 2011):

1. Due to the internal clearance, after driving, the sample must be allowed to expand and adhere to the wall of the sample tube. This time is often long and, even if you wait 24 hours, the sample is often not recovered;

2. the sample falls when the tube is pulled, which is very common - it should be noted that there are two occasions when this fact can occur (i) the first, right at the beginning of the sample removal, when Shelby's head does not work properly, (ii) the second, when the sample is taken from the hole, and the specific weight changes from submerged to natural;

3. When detaching the massif sample, it is necessary to apply a rotation to the tube, which causes the lower part - which could be the most noble of the sample (nozzle) - to undergo strong distortions, where this part ends up being discarded for strength and deformability tests.

IDENTIFIED ANTERIORITIES

There are many types of samplers to collect undisturbed samples of soft clay, both on land and at sea, and the work of Hvorslev (1949) is a basic reference on this subject. The models presented aim to minimize any type of disturbance in the soil sample, as well as seek to resolve the limitations associated with the sample recovery process after driving, with the aim of making the sampling process effective and efficient.

In the first sampler model, represented in CN203025002, the shape commonly known as the piston sampler is observed. The only figure in this document illustrates the soil sampler with a cutting blade across the edge of the tube (11). In this model, there is no mechanism capable of cutting or even isolating the soil sample, which is at the base of the tube, from the rest of the subsoil being sampled (below the base of the sampler). In fact, the recovery of the sample depends solely and exclusively on the friction between the sample and the internal walls of the sampler tube (in addition to the vacuum generated in the piston), as there is no device capable of supporting the sample by its base. In some cases, a restriction is applied to the tube (10), in the form of a start, in order to try to better fix the sample in the tube, at the time of sampling extraction. This model has many disadvantages, in

6/15 especially the effects of denting the sample during the extraction phase.

Analyzing the document US5492021, it is observed the implementation of a disposition, on the edge of the sampler, which was developed for the extraction of samples from high resistance soils. It is thus observed that such a provision 5 could be adapted for use in soft soil sampling, however it must be concluded that such a procedure would result in the loss of part of the sample, due to the collapse of the fins (112), which would inevitably deform the sample of soil contained between its walls. Another fact that stands out is the maintenance of the contact of the sample with the subsoil that is being sampled, by Jane10 Ias (118), a fact that has similarly the same disadvantages as the model represented in CN203025002, but on a less accentuated scale.

Analyzing the documents US4667754 and US4946000, a soil sampler arrangement is observed, in which there is a sample holding element (34). It is a hemispherical structure, with flexible fins, which 15 are kept in an open position by the introduction of a bypass tube (18).

After the setting of the sample, the bypass tube is removed, causing the flexible fins to return to the hemispherical position, causing the separation between the soil sample and the studied subsoil. In these terms, it is understood that the model has the same limitations presented for the model in document 20 US5492021, in addition to providing more disturbances in the sample at the moment the bypass tube (18) is removed, due to its sliding in relation to the mass of sample soil. In addition, greater rigidity of the soil would prevent the closing of the fins, so that the operator would not have knowledge during the sampling operation, causing the system presented to regress 25 to the model presented by the document CN203025002.

Analyzing the document CN202770660, a soil sampler arrangement is observed in this sense, which has numerous blades (3) positioned around the end of the sampling tube (1). Such a device resembles the cutting mechanism of the Sherbrooke sampler (Lefebvre and 30 Poulin, 1979), which is considered the best sampler for use on land (e.g., Hight et al. 1992). However, for very soft soils it may not work properly, since it does not have lateral containment. Thus, the sample can break by its own weight, when it can be sampled. This model has as limitations a higher energy expenditure during its driving into the ground, 35 due to the greater contact surface of its edge (1), which directly impacts the disturbance of the sample structure. In addition to this model, a complex flow transmission system, to operate the rotation of the blades (3), as well as, illustrated in its design, the blades (3) in the closed position, do not close

7/15 completely based on the soil mass sampled, which causes changes in the stress state of the sample in addition to the stress relief existing in the case of “perfect sampling” (see Ladd and DeGroot, 2003).

Analyzing the model of documents CN202401459 and CN202648989, the illustrated sampler has a soil sample segregation mechanism composed by the union of circular sectors (6), until completing a base disk. In this case, the mechanism closes the sectors (6), separating and at the same time pushing up the soil sample confined to the sampler. This displacement generates an additional disturbance in the sample body, CN202401459 since the relative displacement of the sample between the walls (5) of the sampler occurs during this operation. In this case, there is also a complex mechanism of cutting operation, and, as in CN202770660, it presents potential for failure of mescanism due to the various moving parts involved, adding to another disturbance of the sample during the closing of the circular sectors.

Analyzing the model of document CN202886135, there is a similarity between the cut-support mechanism of that sampler (Figs. 1, 2 and 3) with that of the sampler presented here. This similarity is only apparent. In reality, this similarity only refers to the sample cutting and support operations. However, the sampler of document CN202886135 does not allow that, during the sampling spike in the soil, this “flows between the support-cutting device and the tube, which causes the denting of the soil to be sampled, that is, the sample collected by that sampler can in no way be considered a sample of the undisturbed type.

Analyzing the model of document FR2523613A1, it turns out that it is a sampler capable of recovering samples of soft soils only superficial, as detailed in that document. In fact, although the cutting support mechanism appears to have some similarity to that of the model presented in this document, in reality the mechanism of document FR2523613A1 can only be operated from the ground surface, when cutting, and at no other depth. The model presented in this document performs sampling at any depth, from pre-holes, and during the setting of the sampler, in each sampling process, the soil “flows” between the pipe wall and the cutting-support device.

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INVENTIVE CONCEPT

Considering the research and development efforts in soft soil samplers, it was found that it would be desirable for a new sampler to be developed, to have a device at its base that would cut the sample, such as the Sherbrooke sampler, and that, in addition , support the sample. In fact, the experience with the use of the Sherbrooke sampler in a very soft clay (Oliveira, 2002) made clear the need for lateral containment of the sample. Soon a cut-support mechanism was designed in order to cut the sample without pushing and supporting it at the moment of extraction, in order to prevent slipping. The cut-support device at the base should provide a cut with minimal disturbance to the sample, as well as ensure support across the bottom of the sample, unlike the Sherbrooke sampler. The cutting-support device was designed to be a spherical cap, outside the sampling tube, designed to make the soft soil flow between the sampling tube and the device during the sampling pitting process, which is essential so as not to generate dents during the driving process. The combination of the tube and the cutting-support device would allow, after cutting the sample, integral support, either at the base or on the lateral surface of the sample. This lower support would bring the following advantages:

1. avoid the need for internal clearance;

2. would avoid the need to wait for the pore pressure generated in the soil shearing by the tube to dissipate, with the consequent resistance gain, which is necessary for the recovery of the sample, both in cases of existence and lack of internal clearance ;

3. avoid the imposition of suction at the base of the sample, which occurs in thin-walled samplers (Shelby type) and even in piston samplers;

4. Since there is no need for internal friction of the tube for the sample to be recovered, some type of internal lubricant can be used in the tube walls, in order to reduce the shear stresses at the lateral end of the sample and the redistribution pore-pressures that follow the setting of the sampler;

5. It would avoid distortions (denting), as it would not be necessary to rotate the tube to separate the sample from the solid.

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In addition, it would still be desirable that the new sampler, like the piston sampler, would guarantee the expulsion of the plug generated in the process of pre-drilling, which does not happen with the thin-wall sampler (type Shelby). Once the research objectives were outlined, a sampler was developed for soft and very soft soils with a jaw device, driven by cables, and with soil flow between the jaws and the sampling tube, which has three main parts:

1. bottom and main part of the sampler, which has the sample cutting mechanism, still capable of supporting the sample weight. The cut-support mechanism was designed so that it had a section projected on a very small horizontal plane in the open condition (Fig. 17), in order to offer the least possible resistance during the driving of the sampler, to avoid denting the soil to be sampled. The cutting support mechanism describes a spherical cap. Its activation is made through steel cables, operated from the surface. The bevel cutting angle can range from 5 to 20 °;

2. sampling tube, fixed to the bottom by simple fitting and in order to guarantee constant internal section throughout the entire sampler. In other words, the new sampler has no internal clearance, or rebounds, for the reasons discussed above. Depending on market availability, brass tubes with an internal diameter of 102.5 mm and a thickness of 3 mm were used. The length of the tube is 700 mm, however, the sampler concept allows the use not only of tubes of different dimensions but also of different materials (PVC, for example).

3. sampler head, which serves to fix the tube on the sampling rod and the existing holes, for the passage of water and suspended material during the sampling descent and during the driving.

It should also be noted that the lower part is removable and reassembled at each sampling, while the sampling tube is replaced in each sample.

Some interesting features of the new sampler can be seen:

1. the cut-support mechanism has been designed in such a way that it has a section designed as small as possible, in order to offer the least possible resistance to driving (Fig. 17). The idea was that the soil external to the tube would flow, during the driving, between the external wall of the pipe and the cutting mechanism, thus minimizing the denting of the sample during the driving process of the sampler;

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2. the cutting-support mechanism closes completely, allowing samples to be obtained even from extremely soft soils.

MODEL ADVANTAGES

The present proposal for a new sampler for soft and very soft soils with a jaw device, driven by cables, and with soil flow between the jaws and the sampling tube has the following advantages in relation to the state of the art of the object in question:

1. when compared to samplers that have a sampling tube, it allows the inner wall of the tube to be greased with some lubricating material (silicone, for example) in order to reduce friction, since in an ideal sampling process there would be no friction between the ground and the pipe wall. This process, of course, is not possible in a thin-walled tube (even with a piston), since there is a need for friction to recover the sample;

2. With the new sampler, you can be sure that the sample is recovered. In addition, there is greater productivity with the new sampler, since there is no need for any waiting time for the sample to be recovered, unlike thin-walled samplers (Shelby type) and even piston;

3. cutting with the cutting-support device is much less damaging to the sample than torsional shear in the case of the thin wall sampler and the piston sampler. In addition, the part of the sample to be used in laboratory tests is located well above the cutting region;

4. even if the tube head was efficient, that is, if it was able to always generate vacuum at the top of the sample, this does not prevent vacuum from being generated at the bottom of the sample at the time of extraction, in the case of the thin-walled sampler . The same is true for piston samplers. In the case of the new sampler, the support by the base prevents this great variation of total tension on the sample;

5. when compared to the Sherbrooke sampler, it provides full lateral restriction for both the lateral surface and the base, allowing the removal of very soft samples, which does not happen with that sampler.

6. when compared to samplers that are capable of recovering samples in depth and have cutting-support mechanisms, the

11/15 has the advantage of allowing the acquisition of undisturbed samples, as the existing ones cause great disturbance during the driving process.

7. when compared to a sampler that has a cut-off mechanism and minor disturbance, it has the advantage of not only obtaining superficial samples of the soil but also in depth.

ILLUSTRATIONS

In order to facilitate research and provide understanding of this patent, as recommended in the report, according to a basic and preferred form of realization prepared by the depositor, reference is made to the attached illustrations, which integrate and subsidize this descriptive report where, a:

Figure 1 - It presents the new sampler (100), in exploded view, showing all its constituent elements, necessary for its operation, capable of showing the technical-functional improvements presented in the previous section.

Figure 2 - Shows the top view of the sampling containment disc (110).

Figure 3 - Shows the top view of the sampler head (120).

Figure 4 - Shows the side section view A-A of the sampler head (120).

Figure 5 - Shows the top view of the guide ring (130).

Figure 6 - Shows the side section view B-B of the guide ring (130).

Figure 7 - Shows the top view of the connection sleeve (150).

Figure 8 - Shows the D-D side section view of the connection sleeve (150).

Figure 9 - Shows the top view of the sampler tip (160).

Figure 10 - Shows the E-E side section view of the sampler tip (160).

Figure 11 - Shows the front view and the side section view F-F of the articulation plate (170) of the cutting jaws (200).

Figure 12 - Shows the front and side views of the containment rod (180) of the sampler.

Figure 13 - Shows the front and side views of the drive rod (190) of the cutting jaws (200).

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Figure 14 - Shows the front view of the opening control rod (220) of the cutting jaws (200).

Figure 15 - Shows the front, side and top views of the cutting jaw (200).

Figure 16 - Shows the top view of the sampler with the cutting jaws open.

Figure 17 - Shows the bottom view of the sampler with the cutting jaws open.

Figure 18 - Shows the side view of the sampler during the sampler descent process, penetrating the soil, with the jaws open and the soil flowing between the tube and the jaws.

Figure 19 - Shows the side view of the sampler after the interruption of soil penetration, in the process of closing the jaws.

Figure 20 - Shows the side view of the sampler, with the jaws closed, before the start of the sampler's ascent with the sample inside.

Figure 21 - Shows the side view of the sampler during the ascent, with the sample inside.

DESCRIPTION

As can be seen from the figures presented, the object of the present patent is composed of a tube (140) where in its upper part the guide ring (130), the head (120) and the containment (110). At its base, the tube (140) receives, in order, the connection sleeve (150), followed by the tip (160) of the sampler. All the listed elements are connected to each other, and stabilized through the containment rods (180). The cutting mechanism is represented by the jaws (200), which pivot on the articulation plate (170), which are attached diametrically to the tip (160) of the sampler. The actuation of the jaws (200), to make the cut in the soil sample, is carried out by the actuation rods (190) and such actuation can be reversed through the opening command rods (220).

The containment disc (110) consists of a thick steel plate, which contains on its outer edge the fixing guides (111) and the holes (112) in its body. The fixing guides (111) receive the dowels (181), where they are fixed with nuts and lock washers. The holes (112) receive

13/15 hexagon head screws, fixing them in the holes (123), joining the retaining disc (110) to the sampler head (120).

The sampler head (120) is composed of a disc (125) in thick steel plate, attached in its center by the tube (124), threaded inside, and the tube (122), whose external diameter (126) is equivalent to the inner diameter (133) of the guide ring (130). The disc (125) has the fixing holes (123) and the holes (121) for draining and venting air during the entire sampling process.

The guide ring (130), composed of a tube, has around it the fixing guides (131), which receive the billets (181) and the steel cables (194) and the dowels (191) of the drive rods (190), the steel cables and opening control tie rods (220). The existing shoulder (132) receives the end of the tube (140), in order to couple the tube (140) and the guide ring (130) without internal projections, to allow the insertion of the tube (122) without the existence of clearances.

The connection sleeve (150), in the form of a tube, has an internal diameter (152) in the dimensions of the external diameter of the tube (140). The shoulder (151) accommodates next to the shoulder (163) of the tip (160) of the sampler.

The tip (160) of the sampler, in the form of a tube, has the shoulder (161) that accommodates the tip of the tube (140), so as not to allow looseness or bumps in its union. The tip (160) has a beveled end (164), which constitutes its driving blade. The articulation plates (170), which are welded or screwed to the tip body (160), are positioned diametrically opposite. Anchors (182) of the containment rods (180) around the end (160) are also screwed, welded or riveted.

The articulation plates (170), composed of a thin steel plate, have holes (173) in order to position the screws, weld points or rivets, for their fixation to the tip (160). At the top of the plate (170) there is a solid prism (171) that contains the closing movement of the cutting jaws (200). In the center of the plate (170) resides the pivot (172), in which the cutting jaws (200) are fixed, which can be fixed by means of nuts with pressure washers, or even rivets.

The cutting jaws (200) pivot under the pivot (172). They have arms (201), which contain the hole (202) that receives the pivot (172) and the other hole (203) that receives the pin (195), to fix the jaw (200) to the drive rod (180) . The jaw (200) is formed by a spherical steel cap (204) that

14/15 has at its end a beveled blade (205), and in the upper area of the cap (204), a eyelet (241) for fixing the opening control rod (220), by fixing the loop (223) ).

The containment rods (180) are composed of the billets (181), which have their threadable ends. They are connected to the anchors (182) by means of steel cables. The drive rods (190) consist of a steel cable (194) which runs through a dowel (191), and is attached to the knot (192). This node (192) connects two more steel cables, which are then attached to the coupling (193), which consists of a kneecap by means of the pin (195). The opening control rods (220) consist of a steel cable (221), a dowel (222) and a loop (223) at its end.

The use of the new sampler starts with the jaws (200) in the open position, as can be seen in Figure 18. After the event of driving the sampler into the soil to be sampled, the drive rods (190) are activated through the cables (194), which, when pulled upwards, operate the pivoting of the manibulas (200) by the pivots (172), performing the occlusion of the jaws (200), cutting the soil sample contained inside the tip (160) of the sampler . Thus, when the sampler is extracted from the soil, the sample rises together, supported by the jaws (200) that are closed during the procedure. Due to this mechanism, there is no longer any need for any waiting time for the sample to be detached and extracted.

CONCLUSION

In this way, the sampler for soft and very soft soils with a jaw device, driven by cables, and with soil flow between the jaws and the sampling tube is subsidized by unprecedented technical and functional characteristics, presenting an inventive act, based on an entire research applied, undertaken throughout its development, and therefore deserves the legal protection sought. Although it has been described and illustrated, it is worth mentioning that design changes are possible and achievable, without departing from the scope of this utility model.

BIBLIOGRAPHIC REFERENCES

HIGHT, D.W., BOESE, R „BUTCHER, A.P., CLAYTON, C.R.I. SMITH, P.R, 1992, Disturbance of Bothkennar clay prior to Laboratory Testing. Geotechnique, v. 42,

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η. 2, pp. 199-217.

HIGHT, D.W., LEROUEIL, S., 2003, Characterization of soils for engineering purposes. Characterization and Engineering Properties of Natural Soils - Tan et al. (eds.), Swets & Zeitlinger, Lisse, v.1, pp. 255-360.

HVORSLEV, M.J., 1949, Subsurface exploration and sampling of soils for civil engineering purposes. The waterways experiment station, Corps of Engineers, U.S. Army, Vicksburg, Miss, 521 p.

LADD, C.C., 1973, Estimating settlements of structures supported on cohesive soils, revision of a paper originally prepared for M.I.T., 1971, Special Summer Program, Soft Ground Construction, Cambridge.

LADD, C., DEGROOT, D., 2003, Recommended practice for soft ground site characterization: Arthur Casagrande Lecture. In: Proceedings of the 12th Panamerican Conference on Soil Mechanics and Geotechnical Engineering, Boston, v. 1, pp. 3-57.

LEFEBVRE, G., POULIN, C., 1979, A new method of sampling in sensitive clay. Canadian Geotechnical Journal, Vol. 16, n. 1, pp. 226-233.

LEROUEIL, S., HIGHT, D.W., 2003, Behavior and properties of natural soils and soft rocks. Characterization and Engineering Properties of Natural Soils - Tan et al. (eds.), Swets & Zeitlinger, Lisse, v.1, pp. 29-254.

LUNNE, T „BERRE, T., STRANDVIK, S., 1997, Sample Disturbance Effects in Soft Low Plastic Norwegian Clay. Recent Developments in Soil and Pavement Mechanics, M. Almeida (Ed.), Balkema, pp. 81-102.

MARTINS, I.S.M., 1983, On a new ratio of voids - tension in soils. Dissertation by M.Sc., COPPE / UFRJ, Rio de Janeiro, RJ, Brazil.

MARTINS I.S.M., 2011, Lecture notes of the Foundation Engineering Extension Course, PROMINP, UFRJ.

MARTINS, I.S.M. and LACERDA, W.A., 1994, On the ratio of voids to effective vertical tension in one-dimensional compression. Soils and Rocks, vol. 17, no. 3, pp. 157-166, São Paulo.

OLIVEIRA, J. T. R. (2002) The influence of sample quality on the stress-strain-resistance behavior of soft clays. Thesis D.Sc., COPPE / UFRJ, Rio de Janeiro.

Claims (2)

1. Sampler for soft and very soft soils with a jaw device, driven by cables, and with soil flow between the jaws and the sampler tube consists of tube (140) and a cutting mechanism characterized by; - two cutting jaws (200) with two arms (201), two pivoting holes (202) and two holes (203) that connect to the drive rod (180), formed by a spherical steel hub (204) that has at its end a beveled blade (205) and a eyelet (241); - a containment disc (110) composed of a thick steel plate, provided on its outer edge with four fixing guides (111) and four holes (112) in its body; - a sampler head (120), consisting of a disc (125) in thick steel plate with four fixing holes (123) and four drainage holes (121), solidified in its center by the tube (124), threaded inside, and to the tube (122), whose external diameter (126) is equivalent to the internal diameter (133) of the guide ring (130); - a guide ring (130), composed of a tube, which has eight guides (131) for fixation and projection (132) around it; - a tube-shaped tip (160) with a shoulder (161), a beveled end (164), two hinge plates (170) diametrically opposed, welded or screwed to the tip body (160) and four anchors ( 182) screwed, welded, or riveted around the tip (160); - two articulation plates (170), composed of a thin steel plate, with nine holes (173), with a solid prism (171) at the top and a pivot (172) that can be threaded in its center; - four containment rods (180) composed of the dowel (181) with threadable end, anchor (182) connected by means of steel cable - two drive rods (190) each composed of steel cable (194) which runs inside a dowel (191), and is attached to the knot (192), attached to two couplings (193) containing a pin ( 195). - two opening control rods (220) each composed of 2/2 1 a steel cable (221), a dowel (222) and a loop (223) at its end.