JPS6326240B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a soil sample sampler, and more particularly to a soil sample sampler that has an improved mechanism for preventing deterioration of soil samples during operation of the sampler.

(b) Prior art A number of testing methods have been established for soil testing depending on the purpose of the test and the properties of the ground, but they can be roughly divided into in-situ tests conducted at the ground investigation site, and tests conducted in the natural state collected from samples. It can be classified into indoor soil tests, in which soil samples in the state of , so-called undisturbed samples, are tested and analyzed in a test facility with testing equipment.

The most common method of in-situ testing is the standard penetration test, in which a hammer weighing 63.5 kg is dropped freely from a height of 75 cm, and the number of blows required to drive a standard penetration sampler 30 cm is measured. It is used to determine the softness and hardness of the soil layer and the type of soil quality.
The problem with the above-mentioned in-situ test is that various disturbances occur in the ground sample taken as a secondary sample, and these disturbances adversely affect the test accuracy and hinder the derivation of accurate test results. However, the in-situ test is applicable to a wide range of soil types and the test method is relatively simple, so its usefulness as a means of providing a general-purpose test is evaluated despite the accompanying disturbances. On the other hand, in order to improve the measurement accuracy of indoor soil tests, it is necessary to collect soil samples as undisturbed samples under conditions where disturbances are unlikely to occur.

Although it is possible to collect samples from a uniform clay layer or a relatively soft sand layer using a known sampler, it is difficult to collect samples from a hard sand layer, a gravel layer, or a ground with a complex stratigraphic structure. It was difficult to collect samples, which was a major obstacle to improving test accuracy.
In other words, the more difficult it is to collect samples, the more complex and unstable the soil structure is and the more problems there are in terms of engineering, so there is a great need to ensure sample collection conditions with high accuracy and minimal disturbance. .

To explain more specifically, the well-known fixed piston type thin wall sampler is originally a sampler for soft and cohesive soil, and when it comes to hard ground such as gravel, it is necessary to statically push the sampler. I can't do anything. In addition, with the Dennison sampler, the tip of the inner tube protrudes slightly more than the tip of the outer tube, so when digging into the ground with the outer tube, the tip of the inner tube protrudes below the outer tube and sinks into the soil. Being pushed. For this reason, the sample is not washed away by the circulating mud, making it possible to ensure sample collection conditions with little disturbance, but the inner tube can only be pushed statically into the soil, similar to a fixed piston type thin wall sampler. Therefore, if the tip of the sampler hits sand, gravel, or hard ground, sampling cannot continue. Next, the swivel-type double core tube for rock, which is used for hard soil layers where it is difficult to apply static push-in type samplers like the one mentioned above, has an outer tube with a metal crown on the tip. It consists of an inner tube fitted into the outer tube via a ball bearing, and the tip of the inner tube is hidden inside the metal crown. Since the outer tube is connected to the boring rod and rotatably supported, sampling work can be carried out even on relatively hard ground by rotating the outer tube. be able to. However, the above swivel type double core
The disadvantage of the tube is that part of the collected sample is washed away by the circulating muddy water supplied between the outer tube and the inner tube, making it difficult to maintain sample collection conditions that are not affected by external disturbances. Securing it is virtually impossible. In addition, various structures have been proposed for the latest sand samplers, but none of these have been sufficiently technically evaluated.
It has not yet reached the practical stage.

If it is not possible to collect samples using the various samplers mentioned above, dry drilling with a single core tube (waterless drilling without using drilling water or circulating mud) is used as a last resort for the sole purpose of sample collection. Another problem with this method is that a sticking phenomenon occurs in the collected sample stored in the core tube. This seizure phenomenon occurs when the core tube rubs against the ground under anhydrous conditions when sampling is performed without supplying drilling water or circulating mud, and the resulting frictional heat causes damage to the sampled soil. This means that the sample is altered in quality and attached to the core tube by seizing. When such a seizing phenomenon occurs, the collected soil sample undergoes significant alteration due to the frictional heat and compaction. This causes a large disturbance to the measured values of indoor soil tests. The seizure phenomenon varies depending on the soil quality of the ground being investigated, but it generally occurs frequently in hard ground when the amount of excavation reaches 10 to 15 cm, and in soft ground when the amount of excavation reaches 20 to 30 cm. . Therefore, in order to avoid the occurrence of the seizure phenomenon, it is necessary to limit the depth of excavation by the core tube within a predetermined limit, but in most cases, as long as a known sampler is used, there is no limit to the depth of excavation. This results in a significant reduction in sample collection capacity.

Thus, as long as conventional samplers are used, it is impossible to ensure dry excavation conditions that can cover all ground types.
Also, many problems were found regarding preventing deterioration of the collected samples.

(b) Object of the Invention The main object of the present invention is to provide a soil sample sampler that can prevent the sample from flowing out due to circulating drilling water and from altering the quality of the sample due to dry excavation.

Another main object of the present invention is to find a new soil sampler structure that can be applied to ground where it is currently impossible to sample.

(C) Structure of the Invention The present invention provides a soil sampler S in which a metal crown 11 is attached to the lower end of an outer tube 6 which is rotatably supported. A plurality of drilling water discharge ports 12 are opened in the upper part of the fixed metal crown cutting edge 13, and on the inner peripheral surface of the metal crown 11 located below the drilling water discharge ports 12,
A soil sample sampler S having a packing 14 fixed thereto for blocking drilling water, which is in close contact with the outer peripheral surface of the lower end of the non-rotating inner pipe 7 which is arranged concentrically with respect to the outer pipe 6.
The main points are as follows.

(d) Example Figure 1 is a partially cutaway front view of the soil sampler in the preparation position before sample collection, and Figure 2 is a partially cutaway front view of the soil sampler after sample collection. It is a diagram. Further, FIG. 3 is a partially cutaway front view showing the operation procedure of the soil sampler according to the present invention. In these drawings, a soil sample sampler S according to the present invention includes a sampler head 2, an outer tube 6 having a metal crown 11 attached to the lower end, and a ball bearing device 3 that connects the sample into the outer tube 6. A fitted inner tube 7 that also serves as a non-rotating sample collection tube, a piston rod 8 that is inserted into the inner tube 7 and maintains a constant sample collection position without rotating, and is screwed to the lower end of the piston rod. Piston body 9 and piston packing 1
0. A locking device 5 consisting of a wedge mechanism and a pressure spring that locks the piston rod 8 in a fixed position in a non-rotating state; a metal packing 14 fixed to the inner peripheral surface of the metal crown 11; It also has a double pipe structure consisting of a plurality of muddy water discharge ports 12 bored at the top of the metal crown cutting edge 13.

The lower end of the inner tube 7 is located slightly above the metal crown cutting edge 13, and the outer tube 6 and the boring rod 1 are connected via a sampler head 2 using a known locking mechanism such as screwing. It is fixed in a monolithic structure. Therefore, the rotational driving force of the boring rod 1 is transmitted to the outer tube 6 via the sampler head 2. The circulating mud water supplied from the pump 16 passes through the inside of the boring rod 1 and flows into the circulating mud water channel formed between the outer pipe 6 and the inner pipe 7, and then reaches the lower end of the outer pipe 6, At this point, the mud is dammed by a metal packing 14 and flows out from the muddy water outlet 12 into the borehole 24. On the other hand, the inner tube 7 is connected to the ball pairing device 3 so that the rotation of the outer tube 6 is not transmitted to the inner tube 7.
However, the inner tube 7 engages with incidental ground equipment such as the tripod tower 19, the piston rod fixture 20, the piston rod fixing rod 21, etc., and reliably prevents rotational movement and vertical movement. A packing 1 of a piston rod 8 and a piston body 9 attached to the lower end of the piston rod.
The locked state is further strengthened by the elastic crimping of 0. The inner tube 7 and the piston body are connected to the piston.
Since they are engaged while maintaining airtightness through the packing 10, the collected soil sample is exposed to the negative pressure of the sample holding chamber 25 surrounded by the inner wall surface of the inner tube 7 and the bottom surface of the piston body 9. It is then sucked in and held without falling off. In this way, the soil sample is sucked by the negative pressure inside the inner tube 7 and is given a strong holding position suitable for preventing it from falling off. In order to prevent the lowering of the piston rod 8, the locking device 5 exerts a kind of wedge effect on the piston rod 8.

Hereinafter, the operating procedure of the present invention will be explained based on FIG. After the apparatus of the present invention is placed in the preparation position shown in FIG. 1, the sampler S is inserted into the borehole 24 and a soil sample is taken at a predetermined depth.

First, while connecting the boring rod 1 to the sampler S, the piston rods 8 are inserted into the boring rod 1 and a predetermined number of piston rods are connected.
After this, the water swivel 18 is screwed onto the upper end of the boring rod 1. The piston rod 8 extends downward through the boring rod 1 and the water swivel 18, and is connected to the inner tube 7 through the piston packing 10 at its lower end.
The piston body 9 that engages with the piston body 9 is screwed,
The upper end of the piston rod 8 is fixed to a tripod tower 19 via a piston rod fixture 20 such as a chain or tumbler. After the sampler S has descended to a predetermined depth, the piston rod 8 and the piston body 9 are set at a sample collection position that is isolated from the rotation of the outer tube 6 during sampling, does not rotate substantially, and does not move vertically. It is given to the sample storage chamber 25. Circulating mud water is pump 1
6 into the sampler S. That is,
The circulating mud flows through a delivery hose 17 and a water swivel 18, flows into a flow path 26 formed between the boring rod 1 and the piston rod 8, and reaches the sampler S. Sampler S
The circulating mud that has reached the metal crown 11 flows down the second flow path 26' formed between the outer pipe 6 and the inner pipe 7, and is discharged from the mud water outlet 12 into the borehole 24. be done. The shavings generated by excavation are sent to the muddy water bag 23 together with the circulating muddy water, and the circulating muddy water from which the shavings have been separated in the muddy water bag is again supplied to the pump 16 for reuse. The sampler S, whose rotational speed and settling speed are controlled by the boring machine 22 while being supplied with such circulating mud water, settles the outer pipe 6 and the inner pipe 7 while scraping the ground, so that a sample is formed at the lower end of the inner pipe 7. The sample holding chamber 25 is then filled with a sample. Since the sample holding chamber 25 is maintained in a negative pressure state by the close contact between the outer peripheral surface of the piston packing 10 and the inner wall surface of the inner tube 7, the sample stored in the sample holding chamber 25 is always kept under a negative pressure condition. Even if a suction force due to negative pressure acts and a relative displacement occurs between the inner tube 7 and the piston rod 8 along the axial direction of these members,
The sample can be secured in a locked state without falling off. Further, the piston rod 8 is fixed at a substantially constant stationary position by the locking device 5, and a sample storage chamber 25 formed at the lower end of the piston rod 8 is secured by the metal packing 14. Since it is isolated from the circulating mud water, it is possible to completely avoid the sample flowing out due to the circulating mud water. Furthermore, the metal crown cutting edge 13 causes a slight dry digging condition in the sample, but since the metal crown cutting edge 13 and the drilling position of the muddy water outlet 12 are close to each other, deterioration of the sample due to insufficient supply of circulating muddy water can occur. , burn-in can be completely prevented.

(E) Effects of the Invention As is clear from the above explanation, the soil sampler according to the present invention prevents the sample from flowing out due to circulating mud or seeping into the sample, and prevents deterioration of the sample due to dry excavation. It has an extremely wide range of applicability as a novel sampling means that can be effectively avoided. That is, the soil sampler according to the present invention can sample sand layers, which have been impossible to sample up to now.
It can also be used in gravel layers, weathered zones, etc., and can bring about significant improvements in the technical field.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view of the soil sampler in the preparation position, and FIG. 2 is a partially cutaway front view of the soil sampler after sample collection.
Furthermore, FIG. 3 is an explanatory diagram of the operating procedure of the soil sampler according to the present invention. 6... Outer pipe, 7... Inner pipe, 11... Metal crown, 12... Drilling water discharge port, 14... Packing for cutting off drilling water, S... Soil sample sampler.

Claims (1)

[Claims] 1. In a soil sampler having a metal crown attached to the lower end of a rotatably supported outer tube, the metal crown has a plurality of metal crown cutting edges fixed to the lower edge of the soil sampler. A drilling water discharge port is opened, and a lower end outer peripheral surface of a non-rotating inner pipe that is arranged concentrically with respect to the outer pipe is attached to the inner peripheral surface of the metal crown located below the drilling water discharge port. A soil sampler characterized by a firmly attached packing for blocking drilling water.