JPS6278310A - Survey and metering method for ground - Google Patents

Abstract

PURPOSE:To exactly survey the ground by a method in which while an outer tube is penetrated into the ground, depth, turning torque, load current value, revolving number, and jet pressure of pressure fluid are measured during the penetrating period and the variations of water level, etc., are measured by sensors after drawing out the outer tube. CONSTITUTION:While an outer tube 1 and the tip of a pile 2 are penetrated into the ground while being turned, and the ground is excavated by driving blades 4. pressure water, etc., is jetted from a nozzle 5 to penetrate the tube 1 into the ground. At the same time, the penetrating speed of the tube 1, turning load current at the tip 2 and body of pile, the revolving number of the tube 1 and the lapsed time, and the jet pressure of pressure water, etc., are detected. The tube 1 and a hollow rod 6 are drawn out by leaving the pile tip 2 and a measuring tube 3 under the ground, and a water level meter 13 is inserted into a porous tube 8. The variation in level of groundwater coming into the tube 8 is measured by the meter 13, and external force is transmitted to a composite material 7 to measured the variation of underground by a vibrometer 9, a strain gauge 10, and a soil pressure meter 11. The variations in water pressure are further measured by a water level meter 12.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is a method for investigating the soil condition while penetrating the ground with a sensor without vibration or noise, and measuring the behavior and displacement of the ground after burial. This relates to survey and measurement methods.

[Conventional technology and problems]

The ground is composed of air, water, and soil particles, and the condition of the ground changes over time due to human and natural actions.

Such changes in the ground over time can cause landslides and the collapse of mountain retaining walls during civil engineering work, and it is necessary to measure ground behavior in order to predict these changes.

The current measurement method for ground behavior is generally to install various sensors independently in the polling hole, but in order to improve the analysis accuracy, it is necessary to conduct a ground survey again. There were problems such as not only increasing time and labor, but also a large amount of expense, and making it difficult to obtain many measurement points.

Therefore, there is currently a need for a proposal for a measurement method that can reliably measure changes in the ground over time.

[Means for solving problems]

In order to solve the above-mentioned problems, this invention provides a sensor for observing the dynamics of the ground in a measurement pipe housed in the outer pipe, and rotates the outer pipe and the pile point provided at the opening at one end of the outer pipe. Pressure fluid is ejected into the ground through the middle pipe inserted into the measurement pipe, and the outer pipe penetrates the ground under a vertical load, and the depth, rotational torque, load current value, rotational speed, and pressure at the time of penetration are measured. In addition to measuring the ejection pressure of the fluid, the outer tube is removed after penetration, and the dynamics of the ground is measured using the sensor installed in the measurement tube.

[For production]

A flexible and water-permeable composite body with a porous tube inside. Various sensors are installed inside the composite body of the measurement tube. A pile tip is attached to the tip of the outer tube housing the measurement tube, and a hollow body is inserted into the porous tube. With the outer pipe connected to the pile tip, rotate the outer pipe to penetrate into the ground, and record the penetration conditions at this time.

After penetration, the outer tube and hollow body are extracted, and sensors inside the composite body left underground detect earth pressure, water pressure, strain, etc. in the ground, and the sensor is lowered into the porous tube to measure the water level. By combining the measured values with the measured data at the time of penetration, changes in the ground and soil quality can be known.

Regarding the measurement records at the time of the above-mentioned penetration, there are the following achievements.

In the method of penetrating piles into the ground, the jetting of pressurized water and the rotation of the piles penetrate the piles without noise or vibration, and the various conditions at the time of penetration, such as penetration depth, rotational load, and rotation speed over time, are In Japanese Patent Publication No. 54-31603, the non-appearance authors proposed a method of measuring and recording the pressure fluid ejected at the tip of each pile.

With the above construction method, by measuring the penetration conditions, it is possible to confirm the penetration of each pile into the supporting layer, and by compiling data from all piles, it is possible to calculate or estimate the total cumulative bearing capacity. There are advantages.

The huge amount of measured values in the above track record contributes to the analysis of this construction method.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Figure 1 shows the underground investigation and measurement process, Figures 2 and 3 are enlarged sectional views of the underground penetration state, and Figure 4 shows the rotary pushing device using the same vertical load.

An outer pipe 1 that penetrates into the ground has a pile tip 2 arranged at its lower end opening, and a measuring tube 3 is housed inside the pile tip 2.

The pile tip 2 is formed into an inverted conical shape that closes the lower end opening of the outer tube 1, and has a plurality of digging blades 4 fixed to its outer circumferential surface, and has an opening at the sharp end along the axis. A hollow body, that is, a hollow rod 6, inserted into the measuring tube 3 is detachably connected by means of a screw structure, etc., and pressurized air or water is ejected from the nozzle hole 5. While rotating the pile tip 2 and the outer pipe 1, the outer pipe 1 is penetrated into the ground.

The measurement tube 3 is made of a flexible and water-permeable composite body 7, such as a sponge, formed into a cylindrical shape with an outer diameter that fits inside the outer tube 1.
and a perforated pipe 8 forming the core of this composite body 7. The hollow rod 6 passes through the perforated pipe 8 in the axial direction and is connected to the pile tip 2.

Various sensors are incorporated into the composite body 7 of the measurement tube 3. These sensors include, for example, a vibration meter 9, a strain gauge 10, an earth pressure gauge 1'1, and a water pressure gauge 12 housed in the composite body 7.
Furthermore, a water level gauge 13 is lowered into the porous pipe 8. The measured values of each of these sensors are input to and recorded in the measurement recording device 14 placed on the ground.

The rotary pushing device shown in FIG. 4 has an excavating device 17 attached to a guide column 16 erected in front of a pile driver 15 so as to move up and down, and a hollow hollow whose upper end is engaged with the output shaft of this excavating device 17. Rotation is imparted to the rod 6 to rotate the outer tube 1 together with the pile tip 2 to penetrate into the ground.

This penetration device is provided with a detection device so that a soil survey can be conducted when the outer tube 1 penetrates.

These detection devices are detailed in Japanese Patent Publication No. 54-31603, and include a current detection device N1 excavation device consisting of a current transformer, etc. for detecting the load current of excavation device 17 in the penetration depth detection device of outer pipe 1. A rotation speed detecting device P1 such as a tachometer is provided at 17. A pressure detecting device Q such as a pressure transducer is connected to a hollow rod connected to the pile tip 2. In addition to transmitting the values to the recorder M by electrical signals, the recorder M displays each measurement signal with an indicator, records it on recording paper 18 with a pen recorder, etc. as shown in FIG. digitized and recorded on a floppy disk.

In the construction method of the present invention using the above-mentioned devices, a measurement pipe 3 is provided inside the outer pipe 1, and the lower female threaded portion of the hollow rod 6 inserted into the porous pipe 8 of the measurement pipe 3 is connected to the pile tip 2. The outer tube 1, the pile tip 2 and the hollow rod 6 are integrated by screwing into a male threaded tube,
The outer tube 13 is supported by a rotary pushing device such as No. 4rXi, the outer tube 1 is erected on the ground to be constructed, and the entire outer tube 1 and the pile tip 2 are pushed in while being rotated.

Excavation is carried out by the digging blade 4 of the pile tip 2, and the ground is loosened by pressure air or pressure water jetted from the nozzle hole 5, and the outer pipe 1 is loosened by the pushing force and rotation due to the vertical load.
is press-fitted into the ground.

In the press-fitting process of the outer tube 1, the penetration speed, the rotational load current at the pile tip and the antibody, the rotation speed of the outer tube and its elapsed time,
Pressure air or pressure water jetting pressure at the tip of the pile tip 2 is detected and recorded.

When the outer tube 1 is press-fitted to a predetermined depth as shown in FIG. 1 IAB and FIG. 2, the hollow rod 6 is then reversed as shown in FIG. 6, pull up and remove the pile tip 2, as shown in the 1st drawing and 3rd drawing.
The water level gauge 13 is inserted into the perforated pipe 8, leaving the measuring pipe 3 in the ground.

Since the measurement pipe 3 has a structure in which a perforated pipe 8 is inserted into the core of the composite body 7, groundwater flows into the inside of the perforated pipe 8, and the water level gauge 1
In addition to being able to measure water level fluctuations using the vibration meter 9, strain gauge 10, and earth pressure gauge 11, external force is transmitted to the composite body 7, and underground fluctuations can be measured using the vibration meter 9, strain gauge 10, and earth pressure gauge 11, and water pressure fluctuations can be measured using the water pressure gauge 12.

By the way, to understand the soil properties obtained by penetrating the outer pipe 1, we analyze the measured values by penetrating several outer pipes and make judgments based on this. Examples of value determination and support capacity determination are shown below.

22, A: Load current value (Amp) T: Penetration time (min/m) P: Ejection pressure (~/cd) Based on the analysis and combination of A and T%P1 above, A: sandy soil, clayey soil , gravel, T: N value, bearing capacity, P: sandy soil, clay soil, permeable layer is determined.

Example of determining N value (sandy soil) N-0,45ff (A-K)+0.9 (clay soil) N=T +2.2 T: Penetration time per Im A: Load current during excavation K: Load current during idle rotation Judgment of bearing capacity.

RF= 1.38 (%φ+4)-72 peripheral surface friction force RP
= 197-0.46) Tip support force A:
Load current T during excavation: Penetration time per 1 m φ: Circumferential area This invention is based on the soil survey data during rotary penetration as described above, and by combining and examining the measurement values from each sensor of the measurement pipe 3. Ground behavior such as underground construction and landslides can be detected in advance.

Next, the 7th rl! The example shown in J is a case where a small diameter outer pipe is press-fitted into the ground by a manual machine, and the examples shown in Figs.
The same parts as those in the figures are given the same reference numerals, and the explanation will be omitted.

For example, the outer tube 1 with the pile tip 2 attached to the tip is 100 to 1
A hollow tube 6' for air supply water made of metal or synthetic resin is inserted along the axis of the measuring tube 3, which has an outer diameter of about 50 nm and is housed inside the outer tube 1. Inside the measurement tube 3,
A piano wire 22 is stretched between the end plate 21 and the pile tip 2, and this piano wire 22 is supported by a piece 23 attached to a hollow tube 6'.
The via wire 23 is used as a sensor such as a strain meter.

Penetration of the outer pipe 6' into the ground is carried out by manually rotating the outer pipe 6' and the pile point 2, with the loading load set according to the soil quality and depth, and by the rotation, jetting of pressurized fluid, and vertical load. , the outer pipe 6' is extracted after penetrating into the ground.

The features of the invention method described above are listed below.

(I) The soil quality is investigated when the outer pipe is penetrated, and underground measurements are taken using the measuring pipe after the outer pipe is pulled out, so changes in the soil strength, water pressure, strain, vibration, etc. of the ground can be known. It becomes possible to detect ground behavior such as underground construction or landslides in advance.

(n) By installing measurement pipes, the supporting ground can be directly determined from the instrument, and the underground earth pressure and water pressure can be changed instantly, allowing for scientific management of underground construction.

(4) Installing a measurement pipe will help prevent construction pollution on the ground due to vibration noise transmitted to the ground by heavy equipment such as pile driving.

(5) By installing a seismometer etc. in the measurement pipe, it is possible to constantly measure ground microtremors and to know the vibration characteristics of the ground due to forced vibration (explosion), and by long-term installation and observation, records of actual earthquakes can be recorded. You can also do that.

By installing a measurement pipe close to the M mountain retaining wall, changes in Tonosho stress and minute deformation due to earth pressure can be detected.

It is possible to prevent accidents caused by the collapse of mountain retaining walls.

(■By making the measurement pipe a durable material and burying it underground at all times, it is possible to predict underground ground displacement to civil engineering and building structures, etc.) in advance.

〔effect〕

As described above, according to the present invention, with the above configuration, it is possible to measure the penetration depth, rotational torque, load current value, and rotational speed during penetration, and to measure the earth pressure, water pressure, distortion, vibration, and water level after penetration. By combining both types of data, ground analysis can be performed more accurately and with high reliability. By performing measurements during and after penetration simultaneously and continuously using the same device, a lower cost construction method can be realized compared to the case where these two measurement means were originally used separately. Furthermore, various sensors to be set in the composite body of the measuring tube can be installed in advance, thereby reducing the amount of work required on site with poor working conditions.

In addition, just by pulling out the outer tube immediately after penetration, the various sensors are placed in a state where they can start measuring, which greatly improves work efficiency and has excellent practical effects.

[Brief explanation of drawings]

Fig. 1 is a process diagram of the measurement method according to the present invention, Fig. 2 is an enlarged sectional view when the outer pipe is penetrated, Fig. 3 is an enlarged sectional view of the measurement pipe with the outer pipe pulled out, and Fig. 4 is the penetration device. FIG. 5 is a block diagram leading to the recorder, FIG. 6 is an explanatory diagram showing an example of recording, and FIG. 7 is a longitudinal sectional view showing an example of a small diameter outer tube. 1...Outer pipe, 2...Pile tip, 3...Measuring tube, 5...
・Nozzle hole, 6... Hollow rod, 7... Composite body, 8
...Perforated tubes Figure 1 (A) CB) (C) CD) Figure 2 Figure 3 Figure 7 Figure 5 and Figure 6

Claims (1)

[Claims] A sensor for observing the dynamics of the ground is installed in a measurement pipe housed inside the outer pipe, and pressure fluid is applied to the ground through a pile tip installed at the opening at one end of the outer pipe and a hollow body inserted into the measurement pipe while rotating the outer pipe. The outer pipe is ejected into the ground under a vertical load, and the depth, rotational torque, load current value, rotational speed, and ejection pressure of the pressure fluid at the time of this penetration are measured.After the penetration, the outer pipe is removed and measured. A ground investigation and measurement method characterized in that the movement of the ground is measured by the sensor provided in the pipe.