JPH0426401B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a method and measurement method for measuring the thickness and strength of backfilling material injected into the back side of a segment assembled inside a tunnel excavated by a shield machine or the like. Regarding equipment.

Conventional technology Conventionally, in order to measure the thickness and strength of backfilling material injected into the back side of an assembled segment, a sampler that can be split into two is inserted into a grout hole drilled in the segment, the material is sampled, and the thickness is measured. A method was used to read the information on a scale. However, with this method, the injection material is disturbed when the sampler is inserted, making it difficult to measure accurate values.Also, since the sampler is driven into the ground behind the sampler, spring water may be generated when the sampler is pulled out, and the sand layer However, this method was not widely adopted. In addition, the strength could not be measured accurately using a conventional cone penetration tester due to the large diameter.

Purpose of the Invention This invention has been made in view of the above circumstances. The purpose is to propose a method and a measuring device for backfilling injection material that can quickly and accurately determine the thickness and strength of backfilling injection material.

Structure of the Invention The gist of the present invention is to provide a method for measuring backfill injection material injected into the back side of a segment, in which a rod having a tip cone with a built-in pressure sensor attached to the tip penetrates into the back side of the segment through a hole drilled in the segment. During this penetration process, the relationship between the penetration depth position of the tip cone and the penetration resistance value and water pressure acting on the tip cone is measured, and the boundary between the backfilling injection material and the ground is detected from changes in the penetration resistance value or water pressure. This is a method for measuring a backfilling injection material, which is characterized in that the thickness of the backfilling injection material layer is determined by determining the thickness of the backfilling injection material layer, and the strength of the backfilling injection material is determined from the penetration resistance value. It is a device.

FIG. 1 shows an embodiment of this measuring method and measuring device. A segment 1 is assembled inside the excavated tunnel, and a backfilling injection material 3 is injected between the back side of the segment and the ground 2. The measuring device consists of an inner tube rod 4 and an outer tube rod 5, with a diameter of 10 to 15 mm.
A double tube rod 6 of about 100 liters, a roughly conical pointed tip cone 7 attached to the tip of the inner tube rod 4, a load cell 8 and a propulsion handle 9 attached to the proximal end of the inner tube rod 4, and a base of the outer tube rod 5. It consists of a displacement type 10 attached near the end. As shown in Figures 2 and 3, the tip cone 7 has a built-in ultra-compact pressure sensor 11 that detects water pressure, and is divided into four equal parts with a central angle of 90° centered on the axis passing through the apex, and the central angle is the opposite vertical angle. two 1/4 conical parts 7-1 in relationship,
7-1 is the other two 1/4 conical parts 7-2, 7-
The lower edge of the conical shape is more protruding than 2. Note that in the drawings, 12 is a through hole communicating with the pressure sensor 11.

To measure the backfilling injection material using this device, the double pipe rod 6 is inserted into the back side of the segment through the grout hole 13 made in the segment 1. The backfilling material 3 injected at this time is used to fill the grout hole 13.
Immediately after segment assembly is completed, a cylindrical styrene foam 14 is stuffed into the grout hole 13 and a grout cap 15 is placed over the hole to prevent it from seeping into the hole and interfering with accurate thickness measurement of the backfilling material. I'll keep it. After backfilling, grout cap 1
A hole with a diameter into which the tip cone 7 can be inserted is drilled from above 5 until it reaches the styrene foam 14, and the double pipe rod 6 is pushed into the hole until the tip cone 7 reaches the backfilling injection material 3. In this state, the displacement meter 10 is set, and the output cables 16 of the displacement meter 10, load cell 8, and water pressure sensor 11 are connected to a recorder (not shown). While checking the recorder, press the propulsion handle 9 to move the double tube rod 6 1cm/
It penetrates into the backfilling injection material 3 at a speed of about 1 minute. After confirming that the penetration resistance value (QC) or water pressure value changes and settles to a constant value, the penetration is completed.
Then, rotate rods 4 and 5 by 90 degrees and pull them out at the same speed as when they were inserted. After being pulled out, the grout hole 13 is filled with a quick-filling cement or the like, and a wooden plug is driven into the grout cap 15 to close it.

The data obtained from this measurement will have a pattern as shown in Figure 6 if the ground is sandy soil, and a pattern as shown in Figure 7 if it is clayey soil. That is,
In the case of cohesive soil, the boundary between the ground layer and the backfilling injection material layer is detected from the penetration resistance value (QC), and the thickness of the injection material layer (T) is determined.
seek. In the case of sandy soil, the boundary between the rock layer and the backfilling material layer is detected using water pressure, and the thickness (T) of the material layer is determined. In addition, the penetration resistance value (qc) of the backfill injection material
By knowing the relationship constant between the strength of the injection material and the strength when the injection material is solidified, the strength of the backfill injection material can be determined from the penetration resistance value (qc). For example, from penetration resistance value (also called cone bearing capacity) qc, unconfined compressive strength qu
= 1/5qc.

In this embodiment, the tip cone 7 is provided with an overhanging portion of 90° conical portions 7-2, 7-2.
The tip cone 7 was rotated 90 degrees and pulled out, and the position of the protruding portion was changed between the time of penetration and the time of withdrawal, and the withdrawal resistance value and water pressure of the tip cone 7 at the time of withdrawal were measured.

The shape of the tip cone 7 may be a conical shape without an overhang as shown in FIGS. 4 and 5. 11 in this figure
1 is a pressure sensor, and 12 is a through hole communicating with the pressure sensor. It is not possible to measure the resistance value of this tip cone when it is pulled out. This method is suitable for detection methods mainly based on water pressure since there is little difference in strength between the backfilling material and the ground.

In addition, if there is a strength difference between the backing material and the ground,
The boundary surface often does not show a very clear peak when the rod is pushed in, but a clear peak appears when the rod is pulled out, so more accurate measurements can be made by measuring the pullout resistance using a cone with an overhang.

Function/Effect This measurement method involves penetrating the back side of the segment with a double-pipe rod, and the thickness and strength of the backfill injection material are determined from changes in the penetration resistance value or water pressure.The thin double-pipe rod is used without taking out the sample. Therefore, measurements can be carried out quickly and accurately even in places with a lot of spring water.

In addition, this measuring device uses a double tube rod to measure the penetration resistance of the tip cone attached to the tip of the inner tube rod, so it is possible to eliminate the influence of penetration friction resistance of the rod part, making accurate measurements possible. shall be.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of the measuring method and measuring device of the embodiment, FIGS. 2 and 3 are a side view of the tip cone with a protrusion, and a-a, bb-direction views; Figures 4 and 5 are side views and a-a, bb-arrow views of the tip cone without an overhang, and Figures 6 and 7 are views of sandy and clayey soils. It is a graph showing the relationship between the tip cone penetration depth position, penetration resistance value, and water pressure. 1... Segment, 2... Earth, 3... Backfill injection material, 4... Inner pipe rod, 5... Outer pipe rod, 6
... Double tube rod, 7 ... Tip cone, 8 ... Load cell, 9 ... Propulsion handle, 10 ... Displacement type, 11 ... Pressure sensor, 12 ... Through hole, 13
... grout hole, 14 ... styrene foam,
15... Grout cap, 16... Output cable.

Claims (1)

[Scope of Claims] 1. In a method for measuring a backfill injection material injected into the back side of a segment, a rod having a tip cone equipped with a built-in pressure sensor is inserted into the back side of the segment through a hole drilled in the segment. During the penetration process, the relationship between the penetration depth position of the tip cone and the penetration resistance value and water pressure acting on the tip cone is measured, and the boundary between the backfilling injection material and the ground is detected from changes in the penetration resistance value or water pressure. A method for measuring a backfill injection material, characterized by determining the thickness of the backfill injection material layer and determining the strength of the backfill injection material from a penetration resistance value. 2 Consisting of an inner tube and an outer tube, a tip cone with a pointed tip and a built-in pressure sensor is attached to the tip of the inner tube, and the backfill injection material injected into the back side of the segment penetrates through a hole drilled in the segment. A double tube rod having a propulsion means, a load cell attached to the proximal end of the inner tube for detecting the penetration resistance value of the tip cone, and a displacement meter for detecting the penetration depth position of the tip cone. Features: Measuring device for backfill injection material.