TWI821140B - Soil liquefaction monitoring device and method - Google Patents

Abstract

A Soil Liquefaction Monitoring method for monitoring the liquefaction of the subsoil in an area, comprising: conducting drilling in the area to obtain backfilling soil; Lowering an outer tube in the area; pushing at least one soil sampler into the outer tube to place the soil inside the soil sampler; extracting the soil sampler to form a borehole; freezing and preserving the soil samples to obtain frozen soil columns; placing a liquefaction monitoring device at the bottom of the borehole; extruding the multiple frozen soil columns from soil samplers, and putting back the frozen soil columns to the borehole according to their relative positions in the borehole; filling up the space between the frozen soil columns and the outer tube with the backfilling soil; and pulling up the outer tube.

Description

Soil liquefaction monitoring device and method

The present invention relates to a soil liquefaction monitoring device and method, which uses a freezing method to backfill soil samples taken from on-site drilling, so that the liquefaction monitoring device can be located at a relatively fixed depth position and maintain the composition of the soil layer above it, so that it can accurately detect Soil liquefaction status.

The old soil liquefaction monitoring method only involves digging out the soil in the area to be detected and then placing the water pressure gauge into the borehole. To detect the condition of the underlying soil, it may be necessary to dig as deep as 50 meters. , there may be layers of clay and silty sand in between, and each layer will have different soil compositions at different depths. The excavated soil can no longer be backfilled into the borehole according to its original position. Generally, only clean sand is backfilled. (e.g., seven centimeters of rock), because it is different from the originally excavated soil, the amount of excess pore water pressure induced by the earthquake measured by hydraulic pressure is different from the actual excess pore water pressure excitation of the original site, making it difficult to accurately monitor soil liquefaction disasters.

A soil liquefaction monitoring method used to monitor the liquefaction degree of the underlying soil in an area. The monitoring method includes: drilling in the area to obtain a supplementary soil; lowering an outer casing in the area; and jacking at least 100% of the outer casing into the outer casing. An earth extractor is used to contain soil in the earth extractors; the at least one earth extractor is taken out to form a borehole; the earth extractors are frozen and preserved to obtain a plurality of frozen soil columns; a liquefaction monitor is placed in The bottom of the borehole; take out the soil extractors and put them back into the borehole according to the relative positions of the soil extractors in the borehole; fill the supplementary soil into the frozen soil columns and the outer casing between; and withdrawing the outer sleeve upwards.

In the method of monitoring the liquefaction degree of the underlying soil in an area according to the present invention, the outer casing is a hollow casing.

In the method of monitoring the liquefaction degree of subsurface soil in an area according to the present invention, the at least one soil retriever and the liquefaction monitor are pushed downward into the borehole by a push rod.

In the method of monitoring the liquefaction degree of subsurface soil in an area of the present invention, the at least one soil extractor includes a top cover, two side walls and a bottom cover. The top cover includes a coupling device to engage the push rod, and the two side walls are snap-fitted. The top cover and the bottom cover include an opening. When the push rod pushes the at least one soil collector to sink, soil can enter the soil collector through the opening of the bottom cover.

In the method of monitoring the liquefaction degree of subsurface soil in an area according to the present invention, the liquefaction monitor includes: a top, the top includes a clamping hole for clamping the push rod; a first opening and a second opening. Penetrating the top and located on both sides of the clamping hole; an outer wall forming an accommodation space with the top; and a soil pressure gauge and a water pressure gauge located in the accommodation space, a soil pressure gauge and a water pressure gauge The monitoring signal line of the pressure gauge is connected to a data acquisition device on the ground surface through a first opening; wherein, the outer wall of the liquefaction monitor is used to sink into the soil.

In the method for monitoring the liquefaction degree of subsurface soil in an area of the present invention, the step of placing the liquefaction monitor at the bottom of the borehole further includes: connecting the first opening of the liquefaction monitor to a signal line protection tube , the signal line is connected to the liquefaction monitor There is a soil pressure gauge and a water pressure gauge inside. The first opening is connected to the signal line before the monitor is lowered and is sealed with waterproof material. The second opening is connected to a breathable water input and output pipe, and the input and output pipe includes a valve. After placing the liquefaction monitor at the bottom of the borehole with the push rod, the valve of the input and output pipe is opened. Fill the input and output pipes with water and air. At this time, the water and air will fill the inside of the liquefaction monitor. Then use the push rod to push the liquefaction monitor into the soil beneath the monitoring area, and the excess water and air will flow out from the input and output pipes. At this time, the valve is closed so that the liquefaction monitor and the soil are adsorbed together.

100:Liquefaction monitor

101:Top

102:Outer wall

103:Card connection hole

105,107: Opening

111: Soil pressure gauge

112:Soil pressure gauge signal line

113:Water pressure gauge

114:Water pressure gauge signal line

200: Outer sleeve

300:Earth extractor

301:Top cover

303: Bottom cover

305,307:Side wall

400:Putter

500: Supplement soil

701: Signal line protection tube

703: Input and output pipe

[Figure 1A] An external schematic diagram of the liquefaction monitor of the present invention.

[Figure 1B] Internal schematic diagram of the liquefaction monitor of the present invention.

[Figure 2] Schematic diagram of the casing of the present invention.

[Figure 3] Schematic diagram of the earth extractor of the present invention.

[Figure 4A] Schematic diagram of the step of removing and replenishing soil in the method of monitoring the degree of soil liquefaction of the present invention.

[Figure 4B] Schematic diagram of the step of lowering the outer casing in the method of monitoring the degree of soil liquefaction of the present invention.

[Figure 4C] Schematic diagram of the step of lowering the soil extractor in the method of monitoring the degree of soil liquefaction of the present invention.

[Figure 4D] Schematic diagram of the steps of lowering the liquefaction monitor in the method of monitoring the degree of soil liquefaction of the present invention.

[Figure 4E] Schematic diagram of the step of returning frozen soil in the method of monitoring the degree of soil liquefaction of the present invention.

First, please refer to Figure 1A, which is a schematic diagram of the liquefaction monitor 100 of the present invention. The liquefaction monitor 100 includes a top 101 and an outer wall 102. The top 101 includes a quick-connect clamping hole 103 that can be used to clamp a push rod 400 (not shown) used to push the liquefaction monitor 100. The top 101 also includes an opening 105 and an opening 107, which penetrate the top 101 and are located on both sides of the clamping hole 103 respectively. Next, please refer to Figure 1B, which is an internal schematic diagram of the liquefaction monitor 100. It is an accommodation space formed by the top 101 and the outer wall 102. The soil pressure gauge 111 and the water pressure gauge 113 can be installed in this accommodation space. For example, It is the inner side of the top 101 or is arranged on the inner side of the outer wall 102 . The liquefaction monitor 100 has a bottomless structure, so the outer wall 102 can be sunk into the soil. Of course, multiple soil pressure gauges or hydraulic pressure gauges can also be assembled according to the measurement method or design requirements.

Please refer to Figure 2, which is a schematic diagram of the outer sleeve 200 of the present invention. The outer sleeve 200 is a hollow structure, the outer diameter D _o of the outer sleeve can be between 10 and 13 cm, the thickness of the outer sleeve t _o can be between 0.5 and 0.7 cm, and the inner diameter D _i can be between 8.6 and 12 cm. The outer casing 200 is mainly used to define the position where the earth retriever 300 is to be sunk.

Please refer to Figure 3, which is a schematic diagram of the earth extractor 300 of the present invention, which can be made of black iron, for example. The soil extractor 300 includes a top cover 301, two side walls 305 and 307, and a bottom cover 303. The top cover 301 includes a coupling device (not shown, such as a quick release structure) to engage the push rod 400. The two side walls 305 and 307 snap into place with the top cover. 301 and the bottom cover 303. The bottom cover 303 includes an opening. When the push rod 400 pushes the soil collector 300 to sink into the soil, the soil can enter the soil collector 300 through the opening of the bottom cover 303. The diameter or peripheral size of the soil collector 300 can be designed to be smaller than the outer diameter D _o of the outer casing 200; and the diameter or peripheral size of the soil collector 300 can be designed to be larger than the size of the liquefaction monitor 100 (for example, the diameter of the outer wall 102). The borehole is formed to accommodate the liquefaction monitor 100 . In addition, the soil extractor 300 can also be designed as a single side wall or even a combination of three or more side walls, depending on the user's design requirements.

Next, the soil liquefaction monitoring method of this invention will be described.

First, please refer to Figure 4A to drill in the area adjacent to the monitoring system installation, and retain the soil removed from the drilling as supplementary soil 500 for the installation hole of the soil liquefaction monitoring system. Although the position filled by the replenished soil 500 in the final stage may not correspond to its original depth position, because the required amount of replenished soil is much less than the soil obtained by the soil extractor 300 in subsequent steps, it does not affect the present invention. Measurement results of soil pressure gauge 111 and water pressure gauge 113.

Next, please refer to Figure 4B to sink the outer sleeve 200 into the soil.

Next, please refer to Figure 4C. At this time, after the push rod 400 and the soil retriever 300 are connected through the top cover 301, a hydraulic reaction frame (or truck or other mechanical equipment) is used to push the push rod 400 and drive the soil retriever. 300 sinks into the soil. At this time, the soil in the soil collector 300 can be maintained within it due to the friction between the soil collector 300 and the diameter of the soil collector 300. Then, the soil collector 300 is pulled up through the push rod 400, and the soil collector 300 is pulled out. 300 is separated from the push rod 400, and then the soil extractor 300 is frozen. Repeat this step to freeze multiple soil extractors 300, and mark their corresponding positions. For example, the first soil extractor 300 taken out is No. 1, which means it is at the top, and the second soil extractor 300 taken out is No. 2. And so on. In this way, frozen Then, the water and soil are combined and maintain their original composition and structure. In addition, two (or more) earth extractors 300 can also be placed at one time, and the two earth extractors 300 can be taken out at one time to reduce the operation time. In this approach, the top and bottom covers of the two earth extractors 300 can be With the snap-on quick-release design, the push rod 400 can be used to push two earth retrievers 300 at one time. In the present invention, if the outer casing 200 is designed to be relatively wide, more than one earth retriever 300 may be accommodated in the drilling area defined by the outer casing 200 at a time. This depends on the user's measurement or design requirements. adjust.

Next, please refer to Figure 4D to connect the first opening 105 of the liquefaction monitor 100 to a signal line protection tube 701 to accommodate the soil pressure gauge signal line 112 and the water pressure gauge signal line 114, and the first opening Before the monitor is lowered, the signal line connection is completed and sealed with waterproof material. A second opening 107 is connected to an input/output pipe 703. The input/output pipe 703 includes a valve to control whether the fluid in it can pass through. Then, use the push rod 400 to place the liquefaction monitor 100 at the bottom of the borehole, open the valve of the input and output pipe 703 and pour water and air into the input and output pipe 703. At this time, the water and air will fill the inside of the liquefaction monitor 100, and then Use the push rod 400 to push the liquefaction monitor 100 into the soil beneath the monitoring area, and excess water and air flow out through the input and output pipe 703. At this time, the valve is closed, and the liquefaction monitor 100 and the soil will be adsorbed together due to external pressure, and The liquefaction monitor 100 can be maintained at a fixed position. In addition, the signal line protection tube 701 is mainly used to accommodate and protect the soil pressure gauge signal line 112 and the water pressure gauge signal line 114.

Next, please refer to Figure 4D to take out 300 pieces of frozen soil from the soil extractor and place it back in the drill hole at its original position. The gap between the frozen soil column and the drill hole is filled with the 500 pieces of supplementary soil obtained in the above steps. At this time, the outer sleeve 200 is withdrawn upward, which is completed. All steps.

Although the technical content of the present invention has been disclosed in the above paragraphs, it is not intended to limit the present invention. Any modifications and modifications made by those skilled in the art without departing from the spirit of the present invention should be included in the scope of the present invention. Therefore, The scope of protection of this creation shall be determined by the appended patent application scope.

200: Outer sleeve

300:Earth extractor

400:Putter

Claims (6)

A soil liquefaction monitoring method used to monitor the liquefaction degree of the underlying soil in an area. The monitoring method includes: drilling in the area to obtain a supplementary soil; placing an outer casing in the area; and placing a jack in the outer casing. At least one soil extractor is used to accommodate soil in the soil extractors; take out the at least one soil extractor to form a borehole; freeze the soil extractors to obtain a plurality of frozen soil columns; place a liquefaction monitor At the bottom of the borehole; take out the frozen soil columns from the soil extractors and put them back into the borehole according to the relative positions of the soil extractors in the borehole; fill the supplementary soil into these soil extractors between the frozen soil column and the outer casing; and withdrawing the outer casing upward. If the monitoring method of claim item 1 is used, the outer casing is a hollow casing. According to the monitoring method of claim 1, the at least one earth retriever and the liquefaction monitor are placed downwardly in the outer casing through a push rod. As in the monitoring method of claim 3, the at least one earth extractor includes a top cover, at least one side wall and a bottom cover. The top cover includes a coupling device to engage the push rod, and the at least one side wall engages the top cover and the bottom cover. The bottom cover includes an opening. When the push rod pushes the at least one soil collector to sink, soil can enter the soil collector through the opening of the bottom cover. For example, the monitoring method of claim 3, the liquefaction monitor includes: A top, the top includes a snap hole for snapping the push rod; a first opening and a second opening penetrate the top; and an outer wall forms an accommodation space with the top; an earth pressure A meter and a water pressure gauge are located in the accommodation space; wherein, the outer wall of the liquefaction monitor is used to sink into the soil. For example, in the monitoring method of claim 5, the step of placing the liquefaction monitor at the bottom of the borehole further includes: connecting the first opening of the liquefaction monitor to a signal line protection tube to allow the signal line to pass through and the first opening is closed in a watertight state, the second opening is connected to an input and output pipe, the input and output pipe includes a valve, and the push rod is used to place the liquefaction monitor behind the bottom of the borehole. , open the valve of the input and output pipe and fill the input and output pipe with water and air. At this time, the water and air will fill the inside of the liquefaction monitor, and then use the push rod to push the liquefaction monitor into the underlying soil of the area. And the excess water and air flow out from the input and output pipes. At this time, the valve is closed so that the liquefaction monitor and the soil are adsorbed together.

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