A method for collecting large-scale undisturbed loess samples

Abstract

The present invention belongs to the field of loess research technology, and specifically relates to a method for collecting large-scale undisturbed loess samples. The method solves the technical problem that the undisturbed soil samples collected by the current loess undisturbed sample collection method are small in size and difficult to carry out large-scale undisturbed loess simulation tests indoors. The method comprises the following steps: selecting a relatively flat site, marking the sample collection area and the surrounding operation channel; marking the positions of the sample, temporary support and bottom operation area on the loess sample; digging through the bottom operation area along the short side of the loess sample, and then placing a high-density foam pad and a tray base in sequence; placing a lifting steel pipe in the gap of the lower frame of the tray base, and selecting a lifting device according to the actual site conditions and the weight of the sample; during lifting, using a shovel or a rope saw to simultaneously peel off the soil in the lifting and cutting areas at both ends of the sample, so that the sample is gradually separated from the temporary support; after the sample is completely peeled off, it is moved to a flat position by a crane, and promptly wrapped and sealed with plastic film to prevent moisture loss in the sample.

Description

Technical Field

[0001] The invention belongs to the technical field of loess research, and in particular relates to a method for collecting large-sized original loess samples. Background Art

[0002] In research on geological disaster prevention and ecological environment restoration and management, it is often necessary to collect undisturbed loess samples for experimental analysis. With the increase in experimental projects and the improvement in test accuracy, the size requirements for undisturbed loess samples are also increasing. Due to the short deposition age, low strength, loose texture and easy cracking of loess, it is difficult to collect large-scale undisturbed soil samples. Currently, the collection of undisturbed loess samples mostly adopts a simple method of manually excavating the soil around the perimeter, wrapping it with plastic sheeting and tape, and then turning the soil sample over to trim the bottom surface. The size of the undisturbed soil samples collected is relatively small, making it difficult to carry out large-scale undisturbed loess simulation tests indoors. Large undisturbed loess samples are heavy and difficult to turn over completely, and the enclosure strength of the plastic sheeting and tape is also insufficient, making it difficult to transport long distances. Summary of the Invention

[0003] The present invention provides a method for collecting large-size undisturbed loess samples in order to solve the technical problem that the undisturbed soil samples collected by the current loess undisturbed sample collection method are small in size and difficult to carry out large-scale undisturbed loess simulation tests indoors.

[0004] The present invention is implemented by adopting the following technical solution: a method for collecting large-scale undisturbed loess samples, comprising the following steps: 1) selecting a relatively flat site, stripping and leveling the topsoil on the top of the site, and marking a sample collection area and a peripheral operating channel surrounding the sample collection area;

[0005] 2) Dig the surrounding working channels to a certain distance below the bottom of the sample to form a large rectangular loess sample in the middle;

[0006] 3) In the long direction of the loess sample, mark the positions of the sample, temporary support and bottom working area according to the sample specifications. The bottom working area is located below the sample and exceeds both ends of the long side of the loess sample in the length direction;

[0007] 4) After digging through the bottom working area along the short side of the loess sample, place the high-density foam pad and the pallet base in sequence, and promptly use temporary support to keep the high-density foam pad and the pallet base 8 close to the bottom of the sample to prevent the sample from collapsing; a skeleton gap is left between the bottom of the pallet base and the temporary support;

[0008] 5) Place high-density foam pads and keel side guards on both sides of the short side of the sample, and place a top lifting support plate on the top, lined with high-density foam pads; place the lifting steel pipe in the gap of the lower frame of the pallet base, and then pass the lifting belt through the lifting steel pipe. Select the appropriate lifting equipment according to the actual site conditions and the weight of the sample. Install a tension gauge between the lifting equipment and the lifting belt to facilitate tension control;

[0009] 6) Before hoisting, first pre-tighten the slings, with a tension greater than the weight of the pallet base, high-density foam pad, keel side guards, hoisting steel pipes and other hoisting equipment, so that the pallet base is close to the bottom of the sample and plays a certain supporting role;

[0010] 7) During hoisting, use a shovel or rope saw to simultaneously peel off the soil in the hoisting and cutting areas at both ends of the sample, so that the sample is gradually separated from the temporary support. Gradually increase the tension of the sling according to the progress of the peeling, so that the tension of the sling and the weight of the peeled part of the sample are relatively balanced to avoid damage to the sample due to stress changes during the peeling process;

[0011] 8) After the sample is completely peeled off, use a crane to move it to a flat position. After smoothing the edges of the sample, wrap and seal it with plastic film in time to prevent moisture loss.

[0012] Step 9): Install high-density foam pads and packaging boards around and on top of the sample in sequence, and fix them together with the bottom pallet base; when tying with binding tape, increase the tension appropriately to make the packaging board close to the sample to prevent the sample from shaking and being damaged during transportation.

[0013] In step 1), the width of the peripheral working channel is 0.6~0.8m.

[0014] In step 2), the surrounding working channel is excavated to at least 0.5m below the bottom surface of sample 4, forming a large rectangular loess sample with a width of 1.0m*height of 1.5m*length of 2m in the middle.

[0015] In step 3), the bottom working area 6 is at a height of 0.4 to 0.5 m.

[0016] The top of the tray base is flat, and the bottom is a plurality of downwardly protruding bosses; the temporary support (multiple) is a trapezoidal structure, connected to the bottom boss of the tray base to support the sample, and a skeleton gap is formed between the bottom of the tray base and the temporary support.

[0017] The present invention utilizes the cohesiveness and shear resistance of the original loess to excavate the bottom working channel and then place the pallet base; during lifting, the soil connected to both ends of the sample is simultaneously peeled off, so that the sample is gradually separated from the temporary support, and the sling tension is gradually increased according to the stripping progress, so that the sling tension and the weight of the stripped part of the sample are kept in relative balance, thereby avoiding damage to the sample due to stress changes during the stripping process.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The process of the present invention can effectively solve the difficulties in collecting large-sized undisturbed loess samples and the problem of low sample collection success rate, provide corresponding technical support for conducting large-scale loess field simulation tests indoors, further study the formation mechanism of loess geological disasters, and prevent and control geological disasters. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the plan layout of the working channel in the present invention.

[0021] Figure 2 Schematic diagram of excavation of the working channel in the present invention.

[0022] Figure 3 Schematic diagram of the sample collection position in the present invention.

[0023] Figure 4 Schematic diagram of the pallet base and temporary support installation in the present invention.

[0024] Figure 5 One of the schematic diagrams of the installation of the lifting auxiliary facilities in the present invention (front view).

[0025] Figure 6 The second schematic diagram of the installation of the lifting auxiliary facilities in the present invention (side view).

[0026] Figure 7 Schematic diagram of hoisting and cutting in the present invention.

[0027] 1-sample collection area, 2-peripheral working channel, 3-loess sample, 4-sample, 5-temporary support, 6-bottom working area, 7-high-density foam pad, 8-tray base, 9-temporary support, 10-tensile force gauge, 11-sling, 12-top lifting support plate, 13-side guard plate with keel, 14-lifting steel pipe, 15-soil in lifting and cutting area. DETAILED DESCRIPTION

[0028] A method for collecting large-scale undisturbed loess samples includes the following steps: 1) selecting a relatively flat site, peeling off the top soil and leveling it, marking a sample collection area 1 and a surrounding working channel 2, wherein the width of the surrounding working channel 2 is about 0.6-0.8 m. Figure 1 shown.

[0029] 2) Dig the surrounding working channel 2 to about 1.5m (0.5m below the bottom of the sample), and form a large rectangular loess sample 3 with a width of 1.0m*height of 1.5m*length of 2m in the middle, such as Figure 2 shown.

[0030] 3) In the long direction of the loess sample 3, mark the positions of the sample 4, temporary support 5 and bottom working area 6 according to the sample specifications. The height of the bottom working area 6 is about 0.4~0.5m. Figure 3 shown.

[0031] 4) After digging through the bottom working area 6 along the short side of the loess sample 3, place the high-density foam pad 7 and the tray base 8 in sequence, and use temporary support 9 in time to keep the high-density foam pad 7 and the tray base 8 close to the bottom of the sample 4 to prevent the sample 4 from collapsing. Figure 4 shown.

[0032] 5) Place high-density foam pads 7 and keel side guards 13 on both sides of the sample 4, and place the top lifting support plate 12 on the top, lined with high-density foam pads 7. Place the lifting steel pipe 14 in the gap of the lower frame of the pallet base 8, and then pass the lifting belt 11 through the lifting steel pipe 14. Select the appropriate lifting equipment according to the actual situation on site and the weight of the sample. Install a tension meter 10 between the lifting equipment and the lifting belt 11 to facilitate the control of tension, such as Figure 5 、 6 shown.

[0033] 6) Before hoisting, first pre-tighten the sling 11 with a tension slightly greater than the weight of the pallet base, formwork (with keel side guards, high-density foam pads), hoisting steel pipes and other hoisting equipment, so that the pallet is close to the bottom of the sample and plays a certain supporting role.

[0034] 7) During hoisting, use a shovel or rope saw to simultaneously peel off the soil 15 in the hoisting and cutting area at both ends of the sample, so that the sample 4 is gradually separated from the temporary support 5, and gradually increase the tension of the sling according to the progress of the peeling, so that the tension of the sling and the weight of the peeled part of the sample are relatively balanced to avoid damage to the sample due to stress changes during the peeling process. Figure 7 shown.

[0035] 8) After the sample is completely peeled off, use a crane to move it to a flat position. After smoothing the edges of the sample, wrap and seal it with plastic film in time to prevent moisture loss.

[0036] 9) Install high-density foam pads 7 and packaging boards around and on top of the sample, securing them to the pallet base. When using the tie wraps, increase the tension appropriately to ensure the packaging boards fit snugly against the sample to prevent shaking and damage during transport.

[0037] This embodiment does not impose any formal restrictions on the shape, structure, etc. of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are within the scope of protection of the technical solution of the present invention.

Claims

1. A method for collecting large-scale undisturbed loess samples, characterized in that: The method comprises the following steps: 1) selecting a relatively flat site, stripping and leveling the topsoil on the site, and then marking a sample collection area (1) and a peripheral operation channel (2) surrounding the sample collection area (1); 2) Dig the peripheral working channel (2) to a certain distance below the bottom surface of the sample (4), forming a large rectangular loess sample (3) in the middle; 3) In the long side direction of the loess sample (3), mark the positions of the sample (4), temporary support (5) and bottom working area (6) according to the sample specifications. The bottom working area (6) is located below the sample (4) and the bottom working area (6) exceeds both ends of the long side of the loess sample (3) in the length direction; 4) After the bottom working area (6) is dug through along the short side of the loess sample (3), a high-density foam pad (7) and a tray base (8) are placed in sequence, and the high-density foam pad (7) and the tray base (8) are promptly attached to the bottom of the sample (4) using temporary support (9) to prevent the sample (4) from collapsing; a skeleton gap is left between the bottom of the tray base (8) and the temporary support (9); 5) Place high-density foam pads (7) and keel side guards (13) on both sides of the short side of the sample (4) in sequence, and place a top lifting support plate (12) on the top, lined with high-density foam pads (7); place the lifting steel pipe (14) in the gap of the lower frame of the pallet base (8), and then insert the lifting belt (11) into the lifting steel pipe (14). Select a suitable lifting device according to the actual situation on site and the weight of the sample, and install a tension meter (10) between the lifting device and the lifting belt (11) to facilitate the control of tension; 6) Before hoisting, first pre-tighten the sling (11) with a tension greater than the weight of the hoisting equipment, including the pallet base (8), high-density foam pad (7), keel side guard (13), and hoisting steel pipe (14), so that the pallet base (8) is close to the bottom of the sample (4) to play a certain supporting role; 7) During the lifting process, use a shovel or a rope saw to simultaneously peel off the soil (15) in the lifting and cutting area at both ends of the sample (4), so that the sample (4) is gradually separated from the temporary support (5), and the tension of the sling (11) is gradually increased according to the progress of the peeling process, so that the tension of the sling (11) and the weight of the peeled portion of the sample (4) are kept relatively balanced, so as to avoid the sample (4) from being damaged due to stress changes during the peeling process; 8) After the sample (4) is completely peeled off, it is moved to a flat position using a crane. After the four sides of the sample (4) are trimmed and leveled, it is promptly wrapped and sealed with plastic film to prevent moisture loss in the sample.

2. The method for collecting large-scale undisturbed loess samples according to claim 1, characterized in that: Also includes step 9): Install high-density foam pads (7) and packaging boards around and on the top of the sample (4) in sequence, and fix them together with the bottom pallet base (8); appropriately increase the tension when tying with the binding straps to make the packaging board close to the sample (4) to prevent the sample (4) from shaking and being damaged during transportation.

3. The method for collecting large-scale undisturbed loess samples according to claim 1 or 2, characterized in that: In step 1), the width of the peripheral working channel (2) is 0.6~0.8m.

4. The method for collecting large-scale undisturbed loess samples according to claim 1 or 2, characterized in that: In step 2), the peripheral working channel (2) is excavated to at least 0.5 m below the bottom surface of the sample (4), forming a large rectangular loess sample (3) with a width of 1.0 m, a height of 1.5 m, and a length of 2 m in the middle.

5. The method for collecting large-scale undisturbed loess samples according to claim 3, characterized in that: In step 2), the peripheral working channel (2) is excavated to at least 0.5m below the bottom surface of the sample (4), forming a large rectangular loess sample (3) with a width of 1.0m*height of 1.5m*length of 2m*.

6. The method for collecting large-scale undisturbed loess samples according to claim 1 or 2, characterized in that: In step 3), the height of the bottom working area (6) is 0.4~0.5m.

7. The method for collecting large-scale undisturbed loess samples according to claim 5, characterized in that: In step 3), the height of the bottom working area (6) is 0.4~0.5m.

8. The method for collecting large-scale undisturbed loess samples according to claim 1 or 2, characterized in that: The top of the tray base (8) is a plane, and the bottom is a plurality of downwardly protruding bosses; the temporary support (9) is a trapezoidal structure, connected to the bottom boss of the tray base (8) to support the sample (4), and a skeleton gap is formed between the bottom of the tray base (8) and the temporary support (9).

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